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  • 1.
    Abali, Bilen Emek
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics. Chair of Continuum Mechanics and Constitutive Theory, Institute of Mechanics, Technische Universität Berlin.
    Modeling magnetohydrodynamics and computation of metal smelting2020In: Energy-based mathematical methods for reactive multiphase flows / [ed] Liero, M.; Mehrmann, V.; Mielke, A.; Peschka, D.; Thomas, M.; Wagner, B., Berlin Mathematics Research Center MATH , 2020, p. 12-13Conference paper (Other academic)
    Abstract [en]

    Ore is a compound including minerals and is found in Earth’s crust. Ore may contain iron, aluminum, copper or even gold. Extracting these metals are called smelting. For aluminum, smelting is driven by electromagnetism, where conductive ore is a viscous melt with high temperatures and is set in motion effected by electromagnetic forces. Simulation of such an application necessitates not only a computational framework but also the consistent set of partial differential equations. Thermomechanics and electromagnetism are both well-studied independently; nevertheless, their interaction is still puzzling.

  • 2. Abdin, Amir
    et al.
    Feyzabi, Kaveh
    Hellman, Oskar
    Nordström, Henrietta
    Rasa, Dilman
    Thaung Tolförs, Gustav
    Öqvist, Per-Olof
    Methods to create compressive stress in high strength steel components2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Residual compressive stresses can be used to increase the lifetime of parts under cyclic stress as they negate the applied tensile stresses that cause crack initiation and propagation in the material. The goal of this project was to investigate methods to induce stresses, their advantages and disadvantages as well as depth and magnitude of induced stresses, and also to find methods of analyzing the induced residual stresses. This was done on behalf of Epiroc Drilling Tools AB in order for them to induce stresses on the insides of their long, narrow and hollow rods, where stress induction is difficult. Shot peening was used as a reference as that is the method currently in use by the company. The results show that the two most promising methods are cavitation peening and laser shock peening; two relatively new methods with large magnitudes and depth of induced stress as well as a great capability of inducing stresses on the hard-to-reach insides of the rods. Ultrasonic needle peening, ultrasonic shot peening as well as induction hardening, cryogenic treatment and friction stir processing were also investigated. Methods of analyzing the stresses include X-ray diffraction and slitting, hole drilling and ultrasonic methods.

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  • 3.
    Ahlgren Peters, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    A SIMULATION WITH FINITE ELEMENTS TO MODEL STEEL SHEET SLITTING: A Master Thesis in Engineering Physics2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A steel slitting process is simulated using FEM (Finite Element Method) in order to see potential defects along the edge in a steel sheet after it has been cut. The model's results were compared to microscope images of the steel sheet in order to verify accuracy. The purpose is conceptual and to find a model that successfully simulates a steel cutting process and (hopefully) how the edge depends on different parameters. The model developed seems to achieve this task, and a more thorough calibration of the model could result in (more) optimal parameters for the machine to use.

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  • 4.
    Al-Mukadam, R.
    et al.
    Tech Univ Clausthal, Inst Nonmetall Mat, Zehntnerstr 2a, D-38678 Clausthal Zellerfeld, Germany..
    Götz, Inga
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Stolpe, M.
    Heraeus AMLOY Technol GmbH, Heraeusstr 12-14, D-63450 Hanau, Germany..
    Deubener, J.
    Tech Univ Clausthal, Inst Nonmetall Mat, Zehntnerstr 2a, D-38678 Clausthal Zellerfeld, Germany..
    Viscosity of metallic glass-forming liquids based on Zr by fast-scanning calorimetry2021In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 221, article id 117370Article in journal (Refereed)
    Abstract [en]

    Fast-scanning calorimetry was applied to retrieve the viscosity of supercooled liquids of the Zr-based bulk metallic glasses (BMGs) Vitreloy 105 and AMZ4 for temperatures from standard glass transition down to similar to 0.78T(g)/T. Characteristic temperatures of the glass transition were translated into viscosity values by means of composition-independent shift factors based on the equivalency between structural relaxation and viscous flow. The extended MYEGA model with a fragile term dominant at high-temperatures and a strong term dominant at low-temperatures describes the entire viscous range. The analysis revealed that Vitreloy 105 and AMZ4 are strong liquids for log(10) eta >= 4.9-5.5. In turn, the fragile-to-strong crossover is centred on 0.69T(g)/T for Vitreloy 105 and on 0.66T(g)/T for AMZ4. The extent of the fragile-to-strong transition was found to be larger for Vitreloy 105 than for AMZ4, while their values agreed well with the inverse relation between transition factor and kinetic fragility of the strong regime established for BMG-forming liquids. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 5.
    Al-Zoubi, Noura
    et al.
    Tafila Tech Univ, Dept Appl Phys, Tafila, Jordan.
    Schonecker, Stephan
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Li, Xiaoqing
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Li, Wei
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden; Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary.
    Elastic properties of 4d transition metal alloys: Values and trends2019In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 159, p. 273-280Article in journal (Refereed)
    Abstract [en]

    Using the Exact Muffin-Tin Orbitals method within the Perdew-Burke-Ernzerhof exchange-correlation approximation for solids and solid surfaces (PBEso1), we study the single crystal elastic constants of 4d transition metals (atomic number Z between 39 and 47) and their binary alloys in the body centered cubic (bcc) and face centered cubic (fcc) structures. Alloys between the first neighbors Z(Z + 1) and between the second neighbors Z(Z + 2) are considered. The lattice constants, bulk moduli and elastic constants are found in good agreement with the available experimental and theoretical data. It is shown that the correlation between the relative tetragonal shear elastic constant C-fcc'-2C(bcc)' and the structural energy difference between the fcc and bcc lattices Delta E is superior to the previously considered models. For a given crystal structure, the equiatomic Z(Z + 2) alloys turn out to have similar structural and elastic properties as the pure elements with atomic number (Z + 1). Furthermore, alloys with composition Z(1-x)(Z + 2)(x) possess similar properties as Z(1-2x)(Z + 1)(2x). The present theoretical data on the structural and the elastic properties of 4d transition metal alloys provides consistent input for coarse scale modeling of material properties.

  • 6.
    Arapan, S.
    et al.
    VSB Tech Univ Ostrava, IT4Innovat, 17 Listopadu 15, CZ-70833 Ostrava, Czech Republic;Univ Burgos, Int Res Ctr Crit Raw Mat & Adv Ind Technol, ICCRAM, Burgos 09001, Spain.
    Nieves, P.
    Univ Burgos, Int Res Ctr Crit Raw Mat & Adv Ind Technol, ICCRAM, Burgos 09001, Spain.
    Cuesta-Lopez, S.
    Univ Burgos, Int Res Ctr Crit Raw Mat & Adv Ind Technol, ICCRAM, Burgos 09001, Spain;Int Ctr Adv Mat & Raw Mat Castilla & Leon, ICAMCyL, Leon 24492, Spain.
    Gusenbauer, M.
    Danube Univ Krems, Dept Integrated Sensor Syst, A-2700 Wiener Neustadt, Austria.
    Oezelt, H.
    Danube Univ Krems, Dept Integrated Sensor Syst, A-2700 Wiener Neustadt, Austria.
    Schrefl, T.
    Danube Univ Krems, Dept Integrated Sensor Syst, A-2700 Wiener Neustadt, Austria.
    Delczeg-Czirjak, Erna Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Herper, Heike C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Orebro Univ, Sch Sci & Engn, SE-70182 Orebro, Sweden.
    Influence of antiphase boundary of the MnAl tau-phase on the energy product2019In: Physical Review Materials, E-ISSN 2475-9953, Vol. 3, no 6, article id 064412Article in journal (Refereed)
    Abstract [en]

    In this paper, we use a multiscale approach to describe a realistic model of a permanent magnet based on MnAl tau-phase and elucidate how the antiphase boundary defects present in this material affect the energy product. We show how the extrinsic properties of a microstructure depend on the intrinsic properties of a structure with defects by performing micromagnetic simulations. For an accurate estimation of the energy product of a realistic permanent magnet based on the MnAl tau-phase with antiphase boundaries, we quantify exchange interaction strength across the antiphase boundary defect with a simple approach derived from first-principles calculations. These two types of calculations, performed at different scales, are linked via atomistic spin-dynamics simulations.

  • 7.
    Autieri, Carmine
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. ..
    Bouhon, Adrien
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Gap opening and large spin–orbit splitting in MX2 (M = Mo,W; X = S,Se,Te) from the interplay between crystal field and hybridisations: insights from ab-initio theory2017In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 97, no 35, p. 3381-3395Article in journal (Refereed)
    Abstract [en]

    By means of first-principles density functional calculations, we study the maximally localised Wannier functions for the 2D transition metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te). We have found that part of the energy gap is opened by the crystal field splitting induced by the X-2-like atoms. The inversion of the band character between the Gamma and the K points of the Brillouin zone is due to the M-M hybridisation. The consequence of this inversion is the closure of the gap in absence of the M-X hybridisation. The M-X hybridisation is the only one that tends to open the gap at every k-point. It is found that the change in the M-X and M-M hybridisation is the main responsible for the difference in the gap between the different dichalcogenide materials. The inversion of the bands gives rise to different spinorbit splitting at Gamma and K point in the valence band. The different character of the gap at Gamma and K point offers the chance to manipulate the semiconducting properties of these compounds. For a bilayer system, the hybridisation between the out-of-plane orbitals and the hybridisation between the in-plane orbitals split the valence band respectively at the Gamma and K point. The splitting in the valence band is opened also without spin-orbit coupling and occurs due to the M-M and X-X hybridisation between the two monolayers. The transition from direct to indirect band gap is governed by the hybridisation between out-of-plane orbitals of different layers and in-plane orbitals of different layers.

  • 8.
    Bamford, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tool wear in turning of titanium alloy Ti–6Al–4V: Challenges and potential solutions for crater wear, diffusion and chip formation2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Titanium alloys are major materials used in the airplane industry, and prospects show that airplane production will double in the next 20 years. Consequently, the demand for cutting tools for machining of titanium alloys will increase. The primary problem when machining titanium alloys is their low thermal conductivity. Crater wear is the main factor limiting tool life, and is generally caused by thermal diffusion due to high temperatures in the tool-chip interface.

    This master’s thesis was performed in collaboration with Sandvik Coromant, with the prospect to increase knowledge of how diffusion and chip formation influences crater wear progression. The aim was to study tool wear of cutting tools when turning Ti–6Al–4V. This was done by testing two different rake face geometries, both coated and uncoated, at cutting speeds of 30–115 m/min. Diffusion was investigated to learn about the impact it has on crater wear. Chips were examined to investigate chip formation and shear strain.

    The coated modified rake face insert showed less crater wear only for the initial few seconds of machining. Uncoated inserts with a modified rake face showed higher diffusion rate and faster crater wear progression than did standard inserts. The standard inserts showed twice as long tool life as did the modified inserts. No significant differences in the chip formation mechanism were found between modified and standard inserts. Cracks were found within shear bands that were thinner than usual, which suggest that the generation of cracks allows less shear deformation.

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  • 9.
    Benn, Felix
    et al.
    School of Mechanical and Aerospace Engineering, Queens University Belfast, Belfast, United Kingdom..
    D'Elia, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    van Gaalen, Kerstin
    Meotec GmbH, Aachen, Germany.; Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland..
    Li, Muzi
    IMDEA Materials Institute, Madrid, Spain..
    Malinov, Savko
    School of Mechanical and Aerospace Engineering, Queens University Belfast, Belfast, United Kingdom..
    Kopp, Alexander
    Meotec GmbH, Aachen, Germany..
    Printability, mechanical and degradation properties of Mg-(x)Zn elemental powder mixes processed by laser powder bed fusion2022In: Additive Manufacturing Letters, ISSN 2772-3690, Vol. 2, article id 100025Article in journal (Refereed)
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  • 10.
    Boeije, M. F. J.
    et al.
    Delft Univ Technol, Fundamental Aspects Mat & Energy, Fac Sci Appl, Mekelweg 15, NL-2629 JB Delft, Netherlands..
    Delczeg-Czirjak, Erna Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    van Dijk, N. H.
    Delft Univ Technol, Fundamental Aspects Mat & Energy, Fac Sci Appl, Mekelweg 15, NL-2629 JB Delft, Netherlands..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bruck, E.
    Delft Univ Technol, Fundamental Aspects Mat & Energy, Fac Sci Appl, Mekelweg 15, NL-2629 JB Delft, Netherlands..
    On the phase stability of CaCu5-type compounds2017In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 722, p. 549-554Article in journal (Refereed)
    Abstract [en]

    We present a hybrid method to inspect the phase stability of compounds having a CaCu5-type crystal structure. This is done using 2D stability plots using the Miedema parameters that are based on the work function and electron density of the constituent elements. Stable compounds are separated from unstable binary compounds, with a probability of 94%. For stable compounds, a linear relation is found, showing a constant ratio of charge transfer and electron density mismatch. DFT calculations show the same trend. Elements from the s, d, f-block are all reliably represented, elements from the p-block are still challenging.

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  • 11.
    Bojestig, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Adhesion of CVD coatings on new cemeted carbides2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Steel turning inserts cemented carbides have a binder phase consisting of cobalt (Co). However, in recent years a study from the United States National Toxicity Program (NTP) found that cobalt powder is carcinogenic upon inhalation. The European Union's REACH have therefore also classified cobalt powder as carcinogenic upon inhalation. The worldwide search to find a replacement has therefore lately intensified. It is important that the alternative binder phase has no negative effects on the properties of the insert. In this thesis the adhesion between a multilayer ceramic chemical vapor deposition (CVD) coating and a cemented carbide with the alternative binder phases consisting of iron (Fe), nickel (Ni) and cobalt (Co) has been studied.

    First of all, the fracture surfaces showed that the CVD coating was able to grow on all cemented carbides, regardless of which binder phase. To evaluate the adhesion, scratch tests were performed on all samples. The results from the scratch tests were not as expected. No chipping of the coating down to the cemented carbide occurred on any of the samples and the samples with the hardest cemented carbide did not get the highest critical load, which it should according to the literature if all other parameters were the same. Instead the sample with the binder phase consisting of 73 wt% iron and 27 wt% nickel had the highest critical load. This is thought to be due to that during the scratch test the binder phase in this cemented carbide would most likely transform into deformation martensite.

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  • 12.
    Bremler, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Fatigue and microstructural study of a 316L austenitic stainless steel marine component produced by Wire Arc Additive Manufacturing (WAAM)2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study, the fatigue- and fracture properties and microstructure of a marine component of austenitic stainless steel 316L manufactured with the novel method Wire Arc Additive Manufacturing were investigated and compared with data from literature. The purpose was to find a critical flaw size in the material related to its fatigue life.

    It was done by studying the microstructure and interpreting fatigue- and mechanical data for the marine component in empirical models related to the fatigue- and fracture properties. Fracture properties were approximated to estimate fatigue life and critical flaw size. Fatigue limit and fatigue threshold were based on hardness test data, fracture toughness, and FADs on Charpy-V impact test data.

    The material manufactured with Wire Arc Additive Manufacturing had superior fatigue properties than cast and rolled equivalents and performed better in the fatigue test than recommendations for austenitic stainless steel in a seawater environment from the British Standard 7910:2019. Due to the conservative model's fatigue limit and fatigue threshold, the results are conservative. The reason for that could be the crack closure properties of the material. The results for fracture toughness are lower than the literature data. This is most likely due to conservative models based on Charpy-V impact test data.

    The most important properties of the fatigue life are the fatigue limit and the fatigue threshold due to their relationship with crack growth. Testing the lifetime of the component in seawater is complex and time-consuming due to the corrosion and the need for low test frequency.

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  • 13.
    Calamba, K. M.
    et al.
    Linköping Univ, Dept Phys Chem & Biol IFM, Nanostruct Mat, SE-58183 Linköping, Sweden.;Univ Lorraine, IJL, CNRS, F-54000 Nancy, France.;Sandvik Coromant AB, SE-12679 Stockholm, Sweden..
    Salamania, J.
    Linköping Univ, Dept Phys Chem & Biol IFM, Nanostruct Mat, SE-58183 Linköping, Sweden..
    Joesaar, M. P. Johansson
    Linköping Univ, Dept Phys Chem & Biol IFM, Nanostruct Mat, SE-58183 Linköping, Sweden.;SECO Tools AB, SE-73782 Fagersta, Sweden..
    Johnson, L. J. S.
    Sandvik Coromant AB, SE-12679 Stockholm, Sweden..
    Boyd, R.
    Linköping Univ, Dept Phys Chem & Biol IFM, Nanostruct Mat, SE-58183 Linköping, Sweden..
    Pierson, J. F.
    Univ Lorraine, IJL, CNRS, F-54000 Nancy, France..
    Sortica, Mauricio A.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Oden, M.
    Linköping Univ, Dept Phys Chem & Biol IFM, Nanostruct Mat, SE-58183 Linköping, Sweden..
    Effect of nitrogen vacancies on the growth, dislocation structure, and decomposition of single crystal epitaxial (Ti1-xAlx)N-y thin films2021In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 203, article id 116509Article in journal (Refereed)
    Abstract [en]

    The effect of varying nitrogen vacancies on the growth, microstructure, spinodal decomposition and hardness values of predominantly single crystal cubic phase c-(Ti1-xAlx)N-y films was investigated. Epitaxial c-(Ti1-xAlx)N-y films with y = 0.67, 0.79, and 0.92 were grown on MgO(001) and MgO(111) substrates by magnetron sputter deposition. High N vacancy c-(Ti1-xAlx)N-0.67 films deposited on MgO(111) contained coherently oriented w-(0001) structures while segregated conical structures were observed on the films grown on MgO(001). High resolution STEM images revealed that the N-deficient growth conditions induced segregation with small compositional fluctuations that increase with the number of N vacancies. Similarly, strain map analysis of the epitaxial c-(Ti1-xAlx)N-y (001) and (111) films show fluctuations in strain concentration that scales with the number of N vacancies and increases during annealing. The spinodal decomposition coarsening rate of the epitaxial c-(Ti1-xAlx)N-y films was observed to increase with decreasing N vacancies. Nanoindentation showed decreasing trends in hardness of the as-deposited films as the N vacancies increase. Isothermal post-anneal at 1100 degrees C in vacuum for 120 min revealed a continuation in the increase in hardness for the film with the largest number of N vacancies (y = 0.67) while the hardness decreased for the films with y = 0.79 and 0.92. These results suggest that nitrogen-deficient depositions of c-(Ti1-xAlx)N-y films help to promote a self-organized phase segregation, while higher N vacancies generally increase the coherency strain which delays the coarsening process and can influence the hardness at high temperatures.

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  • 14.
    Cao, Peiyu
    et al.
    Univ Sci & Technol Beijing, Beijing Adv Innovat Ctr Mat Genome Engn, State Key Lab Adv Met & Mat, Beijing 100083, Peoples R China.;Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China..
    Tian, Fuyang
    Univ Sci & Technol Beijing, Inst Appl Phys, Beijing 100083, Peoples R China..
    Li, Wei
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden..
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.;Inst Solid State Phys & Opt, Wigner Res Ctr Phys, H-1525 Budapest, Hungary..
    Wang, Yandong
    Univ Sci & Technol Beijing, Beijing Adv Innovat Ctr Mat Genome Engn, State Key Lab Adv Met & Mat, Beijing 100083, Peoples R China..
    Ideal superelasticity in Ni-based Heusler alloys2021In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 210, article id 116816Article in journal (Refereed)
    Abstract [en]

    The hysteresis that occurs during superelasticity caused by the stress-induced first-order martensite transformation is sometimes detrimental to the properties of superelastic materials. In this paper, first-principles calculations are performed to systematically investigate the effects of the chemical composition and crystal disorder on the superelasticity of Ni50-xCoxM25Ga25 (M = Mn, Fe) Heusler alloys. Calculations of the stress-strain relation in the studied alloys reproduce the recent experimental findings for nonhysteretic superelasticity within an acceptable range of composition and ordering. We evaluate the Bloch spectral function to study the Fermi surface topology in connection with nonhysteretic superelasticity. We propose the Landau-de Gennes model-dependent critical parameter P-c, which can be used to predict the composition range of nonhysteretic superelastic materials. For the ferromagnetic L2(1) Ni50-xCoxMn25Ga25 and B2 Ni50-xCoxFe25Ga25 alloys, the nonhysteretic superelasticity phenomenon theoretically occurs for Co contents over x = 16 at.% and x = 28 at.%, respectively.

  • 15.
    Carrascosa Flores, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    New Venture Creation in the E-Waste Industry: A Case Study of a Printed Circuit Board Recycling Venture2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In an exponentially growing society, there is a need to contribute to sustainable development throughan efficient use of natural resources, including the ones that are mined. This can be done through circulareconomy initiatives, recycling being one important activity. Additionally, entrepreneurship can takerecycling initiatives which are ideas and accelerate their entry into the market. Taking this motivation,the current investigation has researched the topic of new venture creation in the e-waste industry byusing ImpactPCB, a new venture on printed circuit board recycling, as a case study.A first iteration of a new venture creation process called ‘effectuation’ has been done through keystakeholder identification and posterior interviews of these different actors of the e-waste value chain,such as collectors of e-waste, pre-processors and end processors, with contributions from ecosystemexperts and start-ups in the industry. The analysis of the interviews has yielded requirements whichhave shaped ImpactPCB’s value proposition and helped identify their target market through the use ofthe Value Proposition Canvas. Apart from this finding, constraints and improvement opportunities havealso been identified and used to create a framework that can mainly be used by ventures similar toImpactPCB: science based and first-time entrepreneurs, when looking to develop in the e-wasteindustry.Two major conclusions have been deduced from the study: firstly, pre-treatment is a key activity fora more efficient recovery of metals that are critical for the development of new technologies thatcontribute to the green economy and thus sustainable development. Secondly, understanding customerrequirements is key to generate a value proposition, and this study shows that certain e-waste preprocessing companies are in need of metal and nonmetal separation processes that are focused on nometal loss. The usage of effectual thinking has helped develop a first iteration for a value propositionand it is recommended to continue this process with an emphasis on continuous customer interaction.

    The full text will be freely available from 2024-08-24 10:28
  • 16.
    Choi, Young Won
    et al.
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Dong, Zhihua
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Li, Wei
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Schönecker, Stephan
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Kim, Hansoo
    Korea Univ, Inst High Technol Mat & Devices, Seoul 02841, South Korea.
    Kwon, Se Kyun
    Pohang Univ Sci & Technol, Dept Phys, Pohang 37673, South Korea.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden;Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary.
    Predicting the stacking fault energy of austenitic Fe-Mn-Al (Si) alloys2020In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 187, article id 108392Article in journal (Refereed)
    Abstract [en]

    Aluminum and silicon are common alloying elements for tuning the stacking fault energy (SFE) of high Mn steels. Today the theoretical investigations on the Fe-Mn-Al/Si systems using Density Functional Theory (DFT) are very scarce. In the present study, we employ a state-of-the-art longitudinal spin fluctuations (LSFs) model in combination with DFT for describing the magnetic effects in Fe-Mn based alloys at finite temperature. We find that the traditional DFT-floating spin results fail to explain the experimental trends. However, the DFT-LSFs approach properly captures the Al-induced increase and Si-induced decrease of the SFE of the base alloy in line with the room-temperature observations. This finding highlights the importance of LSFs in describing the Al/Si effects on the SEE of Fe-Mn based alloys. We point out that the effects of the non-magnetic Al and Si additions on the SEE are in fact determined by the magnetic state of the host matrix. In addition, we estimate the role of carbon addition in the alloying effects of Al and Si. The present results provide a convenient pathway to access the important mechanical parameters for designing advanced high-strength alloys. 

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    FULLTEXT01
  • 17.
    Chou, Chia-Ying
    et al.
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Karlsson, Dennis
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Holländer Pettersson, Niklas
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Helander, Thomas
    Kanthal AB, Box 502, 734 27 Hallstahammar, Sweden.
    Harlin, Peter
    Sandvik Additive Manufacturing, Sandvik AB, Box 510, 101 30 Stockholm, Sweden.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Odqvist, Joakim
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Lindwall, Greta
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Precipitation kinetics during post heat treatment of an additively manufactured ferritic stainless steelManuscript (preprint) (Other academic)
  • 18.
    Chou, Chia-Ying
    et al.
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Karlsson, Dennis
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pettersson, Niklas Hollander
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Helander, Thomas
    Kanthal AB, Box 502, S-73427 Hallstahammar, Sweden.
    Harlin, Peter
    Sandv Addit Mfg, S-81181 Sandviken, Sweden.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Odqvist, Joakim
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Lindwall, Greta
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Precipitation Kinetics During Post-heat Treatment of an Additively Manufactured Ferritic Stainless Steel2022In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 53, no 8, p. 3073-3082Article in journal (Refereed)
    Abstract [en]

    The microstructure response of laser-powder bed fusion (L-PBF)-processed ferritic stainless steel (AISI 441) during post-heat treatments is studied in detail. Focus is on the precipitation kinetics of the Nb-rich phases: Laves (Fe2Nb) and the cubic carbo-nitride (NbC), as well as the grain structure evolution. The evolution of the precipitates is characterized using scanning and transmission electron microscopy (SEM and TEM) and the experimental results are used to calibrate precipitation kinetics simulations using the precipitation module (TC-PRISMA) within the Thermo-Calc Software package. The calculations reproduce the main trend for both the mean radii for the Laves phase and the NbC, and the amount of Laves phase, as a function of temperature. The calibrated model can be used to optimize the post-heat treatment of additively manufactured ferritic stainless steel components and offer a creator tool for process and structure linkages in an integrated computational materials engineering (ICME) framework for alloy and process development of additively manufactured ferritic steels.

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    FULLTEXT01
  • 19.
    Czub, J.
    et al.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Przewoznik, J.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    Zarzecka, A.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    Hoser, A.
    Helmholtz Zentrum Berlin, Hahn Meitner Pl 1, D-14109 Berlin, Germany.
    Gondek, L.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    On the properties of the novel CeMgNi2T2 (T = Co, Cu) alloys and their hydrides2020In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 814, article id 152244Article in journal (Refereed)
    Abstract [en]

    In this contribution, we report the results of the studies on the novel CeMgNi2Co2 and CeMgNi2Cu2 alloys and their hydrides/deuterides. Both the parent alloys and the CeMgNi2Co2H6.1 hydride crystallize in the MgCu4Sn-type structure, while the CeMgNi2Cu2H6.0 hydride becomes almost completely amorphous. In the MgCu4Sn structure the 3d metals are distributed over the 16e site forming the pyrochlore lattice. That makes this system particularly interesting as concerns the magnetic properties. Our studies reveal that magnetic susceptibilities of the alloys are weakly temperature-dependent and therefore, the Pauli-like paramagnetism can be suggested. Additionally, the results of the low temperature neutron diffraction experiments revealed the lack of the long-range magnetic ordering.

  • 20.
    Dai, Cheng-ren
    et al.
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China..
    Yang, Zhi-biao
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China..
    Sun, Jian
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China..
    Lu, Song
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden..
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden;Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Composition and temperature dependence of α2 phase decomposition in high Nb-containing lamellar gamma-TiAl alloys: Experiments and first-principles calculations2021In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 221, article id 117419Article in journal (Refereed)
    Abstract [en]

    This paper reports an experimental and theoretical study of composition and temperature dependence of alpha(2) phase decomposition in lamellar gamma-Ti -(43 similar to 47)Al-(4 similar to 10)Nb alloys. The alpha(2) phase decomposes to nano-sized orthorhombic (O) phase in the alloys (the Nb content >= 5.5 at.%) at temperatures of 550 similar to 750 degrees C. The transformation temperature decreases with increasing the Al content, but increases with increasing the Nb content. The Nb partitioning coefficient between O and alpha(2) typically equals to 2, and decreases with increasing the Al content and temperature, confirming that the O phase transformation is controlled by Nb diffusion. The alpha(2) to omega(0) phase transformation takes place in the alloys (the Nb content > 7 at.%) at 800 degrees C. The blocky omega(0) phase is enriched in Nb and the Nb partitioning coefficient between omega(0) and alpha(2) is about 1.3, indicating that the omega(0) phase transformation is also related to Nb diffusion. The pseudo-binary phase diagram calculated by first-principles correctly predicts the alpha(2) to O phase transformation at temperature below 750 degrees C and alpha(2) to omega(0) phase transformation at temperature above 750 degrees C in the alloys. Since the alpha(2) phase is unstable thermodynamically at intermediate temperature, such kinds of alpha(2) to O and omega(0) phase transformations are considered necessarily for design of high Nb-containing gamma-TiAl alloys.

  • 21.
    Daly, Colin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Increased build rate by laser powder bed fusion of SSAB steel powder2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    SSAB has built a pilot gas atomization facility looking to expand their expertise of steel into the metal powder and additive manufacturing industry. Laser powder bed fusion is an additive manufacturing method that melts and fuse metal feedstock powder together layer by layer using a high intensity laser. The complex process requires optimization in order to be competitive. The process parameters laser power, scan speed, hatch distance and layer thickness largely govern the build rate and total production time. To increase the build rate, two iterations of test cubes with unique parameters sets were experimentally printed. Evaluation of relative density, porosity, microstructure, hardness and mechanical properties was performed. All results were compared to a reference parameter set previously studied. A candidate parameter set successfully increased the build rate by 116% while maintaining satisfactory material properties.

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    Exjobb SSAB FINAL
  • 22.
    Dastanpour, Esmat
    et al.
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Huang, Shuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. China Univ Geosci, Fac Mat Sci & Chem, Wuhan 430074, Peoples R China..
    Dong, Zhihua
    Chongqing Univ, Coll Mat Sci & Engn, Natl Engn Res Ctr Magnesium Alloys, Chongqing 400044, Peoples R China.;Chongqing Inst Adv Light Met, Chongqing 400030, Peoples R China..
    Schönecker, Stephan
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Ström, Valter
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Varga, Lajos Karoly
    Wigner Res Ctr Phys, Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.;Wigner Res Ctr Phys, Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Investigation of the metastable spinodally decomposed magnetic CrFe-rich phase in Al doped CrFeCoNi alloy2023In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 939, article id 168794Article in journal (Refereed)
    Abstract [en]

    We have conducted an in-depth study of the magnetic phase due to a spinodal decomposition of the BCC phase of a CrFe-rich composition. This magnetic phase is present after casting (arc melting) or water quenching after annealing at 1250 degrees C for 24 h but is entirely absent after annealing in the interval 900-1100 degrees C for 24 h. Its formation is favored in the temperature interval ca 450-550 degrees C and loses magnetization above 640 degrees C. This ferromagnetic-paramagnetic transition is due to a structural transformation from ferromagnetic BCC into paramagnetic sigma and FCC phases. The conclusion from measurements at different heating rates is that both the transformation leading to the increase of the magnetization due to the spinodal decomposition of the parent phase and the vanishing magnetization at 640 degrees C are diffusion controlled.

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    fulltext
  • 23.
    Dastanpour, Esmat
    et al.
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Huang, Shuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. China Univ Geosci, Fac Mat Sci & Chem, Wuhan 430074, Peoples R China.
    Schönecker, Stephan
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Mao, Huahai
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.;Thermocalc Software AB, Rasundavagen 18, SE-16967 Solna, Sweden..
    Ström, Valter
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden.
    Varga, Lajos Károly
    Wigner Res Ctr Phys, Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden; Wigner Res Ctr Phys, Inst Solid State Phys & Opt, H-1525 Budapest, Hungary.
    On the structural and magnetic properties of Al-rich high entropy alloys: a joint experimental-theoretical study2023In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 56, no 1, article id 015003Article in journal (Refereed)
    Abstract [en]

    The present work investigates how the vanadium (V) content in a series of Al50Vx(Cr0.33Mn0.33Co0.33)(50−x) (x = 12.5, 6.5, 3.5, and 0.5 at.%) high-entropy alloys affects the local magnetic moment and magnetic transition temperature as a step towards developing high-entropy functional materials for magnetic refrigeration. This has been achieved by carrying out experimental investigations on induction melted alloys and comparison to ab initio and thermodynamic calculations. Structural characterization by x-ray diffraction and scanning electron microscopy indicates a dual-phase microstructure containing a disordered body-centered cubic (BCC) phase and a B2 phase with long-range order, which significantly differ in the Co and V contents. Ab initio calculations demonstrate a weaker magnetization and lower magnetic transition temperature (TC) of the BCC phase in comparison with the B2 phase. We find that lower V content increases the B2 phase fraction, the saturation magnetization, and the Curie point, in line with the calculations. This trend is primarily connected with the preferential partition of V in the BCC phase, which however hinders the theoretically predicted antiferromagnetic B2 phase stabilizing effect of V. On the other hand, the chemistry-dependent properties of the ferromagnetic B2 phase suggest that a careful tuning of the composition and phase fractions can open the way towards promising high-entropy magnetic materials.

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    fulltext
  • 24.
    Dastanpour, Esmat
    et al.
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Huang, Shuo
    China Univ Geosci, Fac Mat Sci & Chem, Wuhan 430074, Peoples R China..
    Ström, Valter
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Varga, Lajos Karoly
    Wigner Res Ctr Phys, Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Schönecker, Stephan
    KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    An assessment of the Al50Cr21-xMn17+xCo12 (x=0, 4, 8) high-entropy alloys for magnetocaloric refrigeration application2024In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 984, article id 173977Article in journal (Refereed)
    Abstract [en]

    This study investigates the magnetocaloric potential of the Al50Cr21-xMn17+xCo12 (x=0, 4, 8 at%) high-entropy alloy (HEA) series using integrated experimental and theoretical approaches. Structural analysis by X-ray diffraction and scanning electron microscopy indicate a dual phase containing B2 and body-centered cubic (BCC) structures. Magnetic characterization shows an approximately linear decrease in saturation magnetization and Curie temperature with increasing Cr content. Curie temperatures calculated by Monte Carlo simulations suggest that the measured magnetic properties originate from the B2 phase rather than the BCC phase. The enhanced magnetocaloric effect with decreasing Cr content highlights the attractiveness of HEAs in magnetocaloric applications.

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    fulltext
  • 25.
    Deekhunthod, Rujira Ninni
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Weld Quality in Aluminium Alloys2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aims of this project are to present an understanding in what happens when aluminium-(Al) alloys are welded, and to investigate how the Mg-, Si- and Cr-contents in AA6005A influence the weld strength and cracking susceptibility.

    It is known that heat from welding affects the mechanical properties (strength) of the material. Different heat cycles during welding are one of the main reasons that the strength varies. Welding can cause various phenomena such as decreased strength, porosity, deformation, cracks and corrosion. To minimize these phenomena one has to have a balance between the welding parameters, alloy composition and welding fixture setup. Al alloys are sensitive to heat from welding because they have high heat conductivity and high thermal expansion coefficient. They also deform easily when the material is heated locally. If the material is deformed too much then cracking easily occurs.

    This project has examined how the Mg-, Si- and Cr-contents in AA6005A, affect the welded material. A V-joint with MIG welding is used for producing weld samples. For evaluation Vickers micro-hardness, tensile testing, radiography (X-ray), LOM and SEM with EBSD and EDS was used. The evaluation focuses on mechanical properties and microstructure.

    The results show that small variations of Mg-, Si- and Cr-content do not have any clear effects on the welded material.

    The results from tensile testing show that all samples have failed in the heat affected zone (HAZ). The tensile strength of all samples are higher than standard but the yield strength are lower than standard (EN ISO 10042:2005).

    The lowering in hardness and tensile strength in the HAZ are believed to be a result from beta-phase (AlFeSi), lead to transformation and coarsening of the strengthening and metastable precipitate. The HAZ is wide, ranging about 20 mm from the fusion line in 5 mm thick plate. The microstructure evaluation has shown that the grain size in the HAZ has been influenced while welding.  The EDS analysis shows that a small amount of AlFeSi particles occur in the base material and HAZ but not in the weld seam.

    Future research is suggested to focus on understanding more about ageing, coarsening of beta-phase and precipitation of intermetallic phases.

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    WeldQualityInAluminiumAlloys
  • 26.
    Deng, Yin
    et al.
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;Cent South Univ, Key Lab Nonferrous Met Mat Sci & Engn Hunan Prov, Changsha 410083, Peoples R China..
    Zhu, Xin-wen
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Lai, Yi
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Guo, Yi-fan
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Fu, Le
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Xu, Guo-fu
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;Cent South Univ, Key Lab Nonferrous Met Mat Sci & Engn Hunan Prov, Changsha 410083, Peoples R China..
    Huang, Ji-wu
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;Cent South Univ, Key Lab Nonferrous Met Mat Sci & Engn Hunan Prov, Changsha 410083, Peoples R China..
    Effects of Zr/(Sc plus Zr) microalloying on dynamic recrystallization, dislocation density and hot workability of Al-Mg alloys during hot compression deformation2023In: Transactions of Nonferrous Metals Society of China, ISSN 1003-6326, E-ISSN 2210-3384, Vol. 33, no 3, p. 668-682Article in journal (Refereed)
    Abstract [en]

    The deformation behavior and microstructure characteristics of Al-6.00Mg, Al-6.00Mg-0.10Zr and Al-6.00Mg-0.25Sc-0.10Zr (wt.%) alloys were investigated by hot compression tests and electron microscopy methods. The results show that after deforming under the maximum processing efficiency condition (673 K, 0.01 s-1), dislocation densities of Al-6.00Mg, Al-6.00Mg-0.10Zr and Al-6.00Mg-0.25Sc-0.10Zr alloys are 2.68x1016, 8.93x1016 and 6.1x1017 m-2, respectively. Their dynamic recrystallization fractions are 19.8%, 15.0% and 12.7%, respectively. Kernel average misorientation (KAM) analyses indicate that dislocation accumulation near grain boundaries is enhanced by adding Zr or Sc+Zr. Besides, the established hot processing maps, based on the dynamic material model (DMM), reveal that the addition of Zr or Sc+Zr can reduce the range of low-temperature unstable domain but expand the unstable domain at high temperatures and high strains. The experimental results further verify that under the testing deformation condition, only the Al-6.00Mg-0.25Sc-0.10Zr alloy cracks at 773 K and 1 s-1.

  • 27.
    Ding, Yu
    et al.
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Yu, Haiyang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Lin, Meichao
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Ortiz, Michael
    CALTECH, Grad Aerosp Labs, 1200 E Calif Blvd, Pasadena, CA 91125 USA..
    Xiao, Senbo
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    He, Jianying
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Zhang, Zhiliang
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Hydrogen trapping and diffusion in polycrystalline nickel: The spectrum of grain boundary segregation2024In: Journal of Materials Science & Technology, ISSN 1005-0302, Vol. 173, p. 225-236Article in journal (Refereed)
    Abstract [en]

    Hydrogen as an interstitial solute at grain boundaries (GBs) can have a catastrophic impact on the mechanical properties of many metals. Despite the global research effort, the underlying hydrogen-GB interactions in polycrystals remain inadequately understood. In this study, using Voronoi tessellations and atomistic simulations, we elucidate the hydrogen segregation energy spectrum at the GBs of polycrystalline nickel by exploring all the topologically favorable segregation sites. Three distinct peaks in the energy spectrum are identified, corresponding to different structural fingerprints. The first peak ( -0.205 eV) represents the most favorable segregation sites at GB core, while the second and third peaks account for the sites at GB surface. By incorporating a thermodynamic model, the spectrum enables the determination of the equilibrium hydrogen concentrations at GBs, unveiling a remarkable two to three orders of magnitude increase compared to the bulk hydrogen concentration reported in experimental studies. The identified structures from the GB spectrum exhibit vastly different behaviors in hydrogen segregation and diffusion, with the low-barrier channels inside GB core contributing to short-circuit diffusion, while the high energy gaps between GB and neighboring lattice serving as on-plane diffusion barriers. Mean square displacement analysis further confirms the findings, and shows that the calculated GB diffusion coefficient is three orders of magnitude greater than that of lattice. The present study has a significant implication for practical applications since it offers a tool to bridge the gap between atomic-scale interactions and macroscopic behaviors in engineering materials.& COPY; 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

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    fulltext
  • 28.
    Ding, Yu
    et al.
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Yu, Haiyang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Lin, Meichao
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Zhao, Kai
    Jiangnan Univ, Jiangsu Key Lab Adv Food Mfg Equipment & Technol, Wuxi 214122, Peoples R China..
    Xiao, Senbo
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Vinogradov, Alexey
    Norwegian Univ Sci & Technol NTNU, Dept Mech & Ind Engn, N-7491 Trondheim, Norway..
    Qiao, Lijie
    Univ Sci & Technol Beijing, Beijing Adv Innovat Ctr Mat Genome Engn, Beijing 100083, Peoples R China..
    Ortiz, Michael
    CALTECH, Grad Aerosp Labs, 1200 E Calif Blvd, Pasadena, CA 91125 USA..
    He, Jianying
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Zhang, Zhiliang
    Norwegian Univ Sci & Technol NTNU, Dept Struct Engn, N-7491 Trondheim, Norway..
    Hydrogen-enhanced grain boundary vacancy stockpiling causes transgranular to intergranular fracture transition2022In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 239, article id 118279Article in journal (Refereed)
    Abstract [en]

    The attention to hydrogen embrittlement (HE) has been intensified recently in the light of hydrogen as a carbon-free energy carrier. Despite worldwide research, the multifaceted HE mechanism remains a mat-ter of debate. Here we report an atomistic study of the coupled effect of hydrogen and deformation temperature on the pathway to intergranular fracture of nickel. Uniaxial straining is applied to nickel E5(210)[001] and E9(1-10)[22-1] grain boundaries with or without pre-charged hydrogen at various temperatures. Without hydrogen, vacancy generation at grain boundary is limited and transgranular frac-ture mode dominates. When charged, hydrogen as a booster can enhance strain-induced vacancy genera-tion by up to ten times. This leads to the superabundant vacancy stockpiling at the grain boundary, which agglomerates and nucleates intergranular nanovoids eventually causing intergranular fracture. While hy-drogen tends to persistently enhance vacancy concentration, temperature plays an intriguing dual role as either an enhancer or an inhibitor for vacancy stockpiling. These results show good agreement with recent positron annihilation spectroscopy experiments. An S-shaped quantitative correlation between the proportion of intergranular fracture and vacancy concentration was for the first time derived, highlight-ing the existence of a critical vacancy concentration, beyond which fracture mode will be completely intergranular.

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    fulltext
  • 29.
    Ding, Yu
    et al.
    Department of Structural Engineering, Norwegian University of Science and Technology.
    Yu, Haiyang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Zhao, Kai
    Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Jiangnan University.
    Lin, Meichao
    Department of Structural Engineering, Norwegian University of Science and Technology.
    Xiao, Senbo
    Department of Structural Engineering, Norwegian University of Science and Technology.
    Ortiz, Michael
    Graduate Aerospace Laboratories, California Institute of Technology.
    He, Jianying
    Department of Structural Engineering, Norwegian University of Science and Technology.
    Zhang, Zhiliang
    Department of Structural Engineering, Norwegian University of Science and Technology.
    Hydrogen-induced transgranular to intergranular fracture transition in bi-crystalline nickel2021In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 204, article id 114122Article in journal (Refereed)
    Abstract [en]

    It is known that hydrogen can influence the dislocation plasticity and fracture mode transition of metallic materials, however, the nanoscale interaction mechanism between hydrogen and grain boundary largely remains illusive. By uniaxial straining of bi-crystalline Ni with a Σ5(210)[001] grain boundary, a transgranular to intergranular fracture transition facilitated by hydrogen is elucidated by atomistic modeling, and a specific hydrogen-controlled plasticity mechanism is revealed. Hydrogen is found to form a local atmosphere in the vicinity of grain boundary, which induces a local stress concentration and inhibits the subsequent stress relaxation at the grain boundary during deformation. It is this local stress concentration that promotes earlier dislocation emission, twinning evolution, and generation of more vacancies that facilitate nanovoiding. The nucleation and growth of nanovoids finally leads to intergranular fracture at the grain boundary, in contrast to the transgranular fracture of hydrogen-free sample.

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  • 30.
    Dong, Zhihua
    et al.
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Li, Wei
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Chai, Guocai
    AB Sandvik Mat Technol R&D Ctr, SE-81181 Sandviken, Sweden;Linkoping Univ, Dept Management & Engn, Div Engn Mat, SE-58183 Linkoping, Sweden.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden;Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary.
    Strong temperature - Dependence of Ni -alloying influence on the stacking fault energy in austenitic stainless steel2020In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 178, p. 438-441Article in journal (Refereed)
    Abstract [en]

    Using ab initio alloy theory, we calculate the impact of Ni on the stacking fault energy in austenitic stainless steel as a function of temperature. We show that the influence of Ni strongly couples with temperature. While a positive effect on the stacking fault energy is obtained at ambient temperature, the opposite negative effect is disclosed at elevated temperatures. An important rationale behind is demonstrated to be the variation of magneto-volume coupling induced by Ni alloying. The alloy influence on the finite temperature evolution of Ni impact is evaluated for elements Cr, Mo and N.

  • 31. Dong, Zhihua
    et al.
    Li, Wei
    Long, Mujun
    Gui, Lintao
    Chen, Dengfu
    Huang, Yunwei
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Effect of Temperature Reversion on Hot Ductility and Flow Stress-Strain Curves of C-Mn Continuously Cast Steels2015In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 46, no 4, p. 1885-1894Article in journal (Refereed)
    Abstract [en]

    The influence of temperature reversion in secondary cooling and its reversion rate on hot ductility and flow stress-strain curve of C-Mn steel has been investigated. Tensile specimens were cooled at various regimes. One cooling regime involved cooling at a constant rate of 100 degrees C min(-1) to the test temperature, while the others involved temperature reversion processes at three different reversion rates before deformation. After hot tensile test, the evolution of mechanical properties of steel was analyzed at various scales by means of microstructure observation, ab initio prediction, and thermodynamic calculation. Results indicated that the temperature reversion in secondary cooling led to hot ductility trough occurring at higher temperature with greater depth. With increasing temperature reversion rate, the low temperature end of ductility trough extended toward lower temperature, leading to wider hot ductility trough with slightly reducing depth. Microstructure examinations indicated that the intergranular fracture related to the thin film-like ferrite and (Fe, Mn)S particles did not changed with varying cooling regimes; however, the Widmanstatten ferrite surrounding austenite grains resulted from the temperature reversion process seriously deteriorated the ductility. In addition, after the temperature reversion in secondary cooling, the peak stress on the flow curve slightly declined and the peak of strain to peak stress occurred at higher temperature. With increasing temperature reversion rate, the strain to peak stress slightly increased, while the peak stress showed little variation. The evolution of plastic modulus and strain to peak stress of austenite with varying temperature was in line with the theoretical prediction on Fe. (C) The Minerals, Metals & Materials Society and ASM International 2015

  • 32.
    Dong, Zhihua
    et al.
    KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden; Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary.
    Finite temperature magnetic properties of CrxCoyNi100-x-y medium entropy alloys from first principles2019In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 171, p. 78-82Article in journal (Refereed)
    Abstract [en]

    The magnetic structure of polymorphic Cr-Co-Ni medium entropy alloys is investigated as a function of temperature and chemical composition by ab initio calculations. Besides the thermal lattice expansion, the longitudinal spin fluctuations (LSFs) are accounted for in determining the magnetic state at finite temperature. We show that sizable local magnetic moments persist on all alloy components in the paramagnetic state for both face-centered cubic and hexagonal close-packed structures, and each alloy species exhibits particular temperature and concentration dependencies. The crucial role of LSFs for the finite temperature magnetic state and its impact on the temperature dependent elastic parameters are demonstrated.

  • 33.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thersleff, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Fourdrinier, Lionel
    CRM group, Liège (Belgium).
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Functionalization of steel substrate: influence of barrier nature on element diffusion from the substrate2014Conference paper (Other academic)
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  • 34.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thersleff, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Fourdrinier, Lionel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Surface defect passivation by a thin metallic barrier for Cu(InxGa1-x)Se2 co-evaporation on Cr-steel substrates2016In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 619, p. 220-226Article in journal (Refereed)
    Abstract [en]

    The use of Cr-steel substrates for the fabrication of Cu(In,Ga)Se2 (CIGS) solar cells is highly desirable and is a topic of considerable research interest. However, solar cells on non-treated steel substrates often exhibit decreased performance compared to their homologues on soda lime glass substrates. This is partly attributed to out-diffusion of steel components (Fe, Cr, Mn, etc.) into the solar cell. To avoid this contamination, thin film barriers can be added on top of the steel surface, but they do not always prevent the diffusion completely. In this paper we study the potential of using Cr and Ti as thin barrier layers. We find that local surface defects on the steel, several micrometers in height, lead to cracks in the back contact as well as in the barrier layers. Advanced transmission electron microscopy (TEM) techniques reveal that elemental diffusion and chemical reactions occur at these openings during heat treatments in Se atmosphere. TEM-energy dispersive X-ray spectroscopy (TEM-EDX) analysis in combination with calculation of the solid state diffusion coefficient demonstrate that a Cr-barrier sacrificially protects the Cr-steel substrate, blocking most of the Fe out-diffusion, whereas a Ti-barrier is less efficient.

  • 35.
    Edling, Erika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Börjesson, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Rogeman, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Naim Katea, Sarmad
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Bengtsson, Jenny
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Söderberg Breivik, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wessman, Markus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Rostfritt stål till stora vattentankar utomhus: En jämförelse mellan austenitiska och rostfria stål2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The austenitic stainless steel 316L has been compared to duplex stainless steels to be able to highlight a choice of material for manufacturing of spare tanks used for cooling water at nuclear power stations on the Swedish west coast. In this report 316L and the duplex stainless steels 2205, 2304 and LDX 2404 have been compared according to corrosion resistance, strength, manufacturing aspects and prices. The steels arranged by increasing corrosion resistance: 316L < 2304 < LDX 2404 < 2205. The steels arranged by increasing strength (considering the thickness of the plates needed for construction): 316L < 2304 < LDX 2404 and 2205. The steels arranged by increasing price/tank: 2304 < LDX 2404 < 2205 < 316L. One of the duplex stainless steels is recommended rather than the austenitic stainless steel 316L. In terms of price 2304 is preferable to 2205 and LDX 2404. When it comes to corrosion resistance 2205 is superior to 2304 and can sometimes be considered as unnecessary good and therefore not relevant for this application. 

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  • 36.
    Eggert, Bruno G. F.
    et al.
    Inst Energy Technol IFE, Dept Hydrogen Technol, POB 40, NO-2027 Kjeller, Norway..
    Delczeg-Czirjak, Erna Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Maccari, Fernando
    Tech Univ Darmstadt, Mat Sci, Funct Mat, D-64287 Darmstadt, Germany..
    Kumar, Susmit
    Univ Oslo, Dept Chem, Sem Saelands Vei 26, N-0371 Oslo, Norway..
    Gutfleisch, Oliver
    Tech Univ Darmstadt, Mat Sci, Funct Mat, D-64287 Darmstadt, Germany..
    Fjellvag, Helmer
    Univ Oslo, Dept Chem, Sem Saelands Vei 26, N-0371 Oslo, Norway..
    Hauback, Bjorn C.
    Inst Energy Technol IFE, Dept Hydrogen Technol, POB 40, NO-2027 Kjeller, Norway..
    Frommen, Christoph
    Inst Energy Technol IFE, Dept Hydrogen Technol, POB 40, NO-2027 Kjeller, Norway..
    Exploring V-Fe-Co-Ni-Al and V-Fe-Co-Ni-Cu high entropy alloys for magnetocaloric applications2022In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 921, article id 166040Article in journal (Refereed)
    Abstract [en]

    A series of V1-x-Fe-Co-Ni-Al1+ x and V1-x-Fe-Co-Ni-Cu1+ x high entropy alloys with varying compositions (0 <= x <= 0.75) has been investigated for magnetocaloric applications. Compositions were selected according to established properties, such as configurational entropy, atomic size difference, and enthalpy of mixing. To study the influence of composition on magnetic ordering temperatures, the V and (Al/Cu) contents were changed while the content of Fe, Co and Ni was retained at 20 at. % each. The crystal structure and microstructure of the as-cast alloys were compared to literature phase guidelines and thermodynamic calculations based on the CALPHAD approach. The V-Fe-Co-Ni-Al compounds are monophasic and crystallize in a disordered body centered cubic structure or its ordered B2 variant, while the V-Fe-Co-Ni-Cu compounds are all multiphasic. Magnetic transitions in the V-Fe-Co-Ni-Al system span over 400 K, with Curie temperature ranging from 155 K in equiatomic VFeCoNiAl, to 456 K in non-equiatomic V0.25FeCoNiAl1.75. The V-Fe-Co-Ni-Cu alloys display magnetic transitions that span about 150 K, with Curie temperature ranging from 230 K for equiatomic VFeCoNiCu to 736 K for non-equiatomic V0.25FeCoNiCu1.75. The magnetic properties of the V-Fe-Co-Ni-Cu compounds were evaluated by means of density functional theory. Individual element-specific moments, magnetic exchange integrals between atomic pairs, and Curie temperatures were calculated. V0.85FeCoNiCu1.15 is selected due to its Curie temperature of 329 K, and its calculated isothermal entropy change of 0.75 J/kg.K for a field change of 5 T is comparable to other 3d metal-based high entropy alloys that form disordered solid solutions. (c) 2022 The Author(s). Published by Elsevier B.V. CC_BY_4.0

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  • 37.
    Elsayed, Abdallah
    et al.
    Univ Guelph, Sch Engn, Guelph, ON N1G 2W1, Canada..
    D'Elia, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Ravindran, Comondore
    Ryerson Univ, Ctr Near Net Shape Proc Mat, Toronto, ON M5B 2K3, Canada..
    Sediako, Dimitry
    Univ British Columbia, High Performance Powertrain Mat, Kelowna, BC V1V 1V7, Canada..
    Observing the Effect of Grain Refinement on Crystal Growth of Al and Mg Alloys during Solidification Using In-Situ Neutron Diffraction2022In: Metals, ISSN 2075-4701, Vol. 12, no 5, article id 793Article in journal (Refereed)
    Abstract [en]

    The present research uses in-situ neutron diffraction to examine the effect of grain refinement on grain growth during solidification of Al-5 wt.% Cu and Mg-5 wt.% Zn alloys. The alloys were grain refined through additions of Al-5Ti-1B and Zr, respectively. The in-situ neutron diffraction experiments were carried out by heating the alloys to temperatures above the liquidus and subsequently cooling in 5 or 10 degrees C temperature steps to temperatures below solidus, while being irradiated by thermal neutrons. With the addition of grain refiners, grain size reductions of 92% were observed for both the Al-5 wt.% Cu and Mg-5 wt.% Zn alloys. The refined and unrefined Al-5 wt.% Cu alloys contained alpha-Al with Al2Cu along the grain boundary regions. Differences in Al2Cu morphology were observed in the grain refined alloys. The Mg-5 wt.% Zn alloy contained MgZn intermetallic phases with primary Mg. The refined Mg-5 wt.% Zn-0.7 wt.% Zr alloy contained Mg, MgZn and Zn2Zr phases. In-situ neutron diffraction enabled quantification of individual plane solid fraction growth for the alpha-Al and Al2Cu phases in the Al-Cu alloys, and for alpha-Mg in the Mg alloys. For the unrefined Al-5 wt.% Cu, the coarse microstructure resulted in a rapid solid fraction rise at temperatures just below liquidus followed by a gradual increase in solid fraction until the sample was fully solid. The grain-refined Al-5 wt.% Cu alloys showed a columnar to equiaxed microstructure transition and a more gradual growth in fraction solid throughout solidification. For the Mg-5 wt.% Zn alloy, the more packed (0002) and (10 (1) over bar1) alpha-Mg plane intensities grew at a slower rate than the (10 (1) over bar0) plane intensity, resulting in an irregular grain structure. With the addition of the Zr grain refiner, the Mg-5 wt.% Zn-0.7 wt.% Zr alloy had (10 (1) over bar0), (0002) and (10 (1) over bar1) planes intensities all increasing at similar rates, especially at the early stages of solidification. FactSage (TM) (version 6.4, Montreal, QC, Canada) equilibrium solidification models followed the fraction solid curves developed by tracking the fastest growing planes of the Mg alloys.

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  • 38.
    Ericsson, Anders
    et al.
    Lund University.
    Pacheco, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Marattukalam, Jithin J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Dalgliesh, Robert M.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Fisk, Martin
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Crystallization of a Zr-based metallic glass produced by laser powder bed fusion and suction casting2021In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 571, article id 120891Article in journal (Refereed)
    Abstract [en]

    The crystallization behavior during low-temperature annealing of samples of the Zr59.3Cu28.8Al10.4Nb1.5 (at%) bulk metallic glass produced by suction casting and the laser powder bed fusion (LPBF) process was studied with small-angle neutron scattering (SANS), X-ray diffraction, and scanning electron microscopy. The in-situ SANS measurements during isothermal annealing reveal that the phase separation in the LPBF processed material proceeds at a smaller characteristic length-scale than the cast material. Quantitative analysis of the SANS data shows that, while the crystallization process in both materials proceeds through rapid nucleation followed by diffusion-limited growth, the LPBF processed material crystallizes with a smaller cluster size and at a higher rate. The smaller cluster size is attributed to the elevated oxygen content in the LPBF processed material which reduces the nucleation barrier and thus the thermal stability.

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  • 39.
    Eriksson, Emanuel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Characterization of surface defects caused by ultrasonic cleaning of aluminium2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis studies the behaviour of two aluminium alloys in ultrasonic cleaning at two different intensities, as well as the effect of a cleaning solution, Formula 815 GD-NF on the same surface have been studied with respect to surface roughness and material composition. Methods like Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and 3D topography using white light interferometry (VSI) was used to study the surface and material composition. It was found that both the ultrasonic cleaning, as well as the solution itself both increase surface roughness of the samples. When crossing a threshold in ultrasonic intensity micro jet cavitation dislodge precipitates, or areas weakened by precipitate to form a large pit. And the following heat from the jet causes the surface to oxidise, becoming more brittle, and be broken up by other cavitation phenomena to cause rapid acceleration of surface roughness in an area originating from the pit. 

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    Characterization of surface defects caused by ultrasonic cleaning of aluminium
  • 40.
    Eriksson, Jenny
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Galling of high strength steels and stainless steels in sheet metal forming as evaluated using pin-on-disc testing2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis focuses on the problem galling in sheet metal forming operations. Galling occurs when sheet metal transfers from the sheet surface onto the tool surface and causes surface damages to following sheets in the forming operation. When this happens the tool must be replaced causing production stops and additional expenses.

    The increasing use of high strength steel grades combined with the desire to use more environmentally friendly or no lubricants exposes the tools used for sheet metal forming for tougher forming conditions with higher contact pressures and thus an increasing risk for material pick-up and galling. To prevent this new tool steels, lubricants and coatings have been developed. In this thesis a number of tool steels, high strength steels, stainless steels, coatings and lubricants have been investigated with the test method pin-on-disc testing in order to explain how different premises, such as chemical composition, mechanical properties and surface topography influence on the galling tendency in sheet metal forming.

    The results show that there is a big difference in performance between a conventional cast tool steel and a powder metallurgy tool steel with respect to the galling tendency. The results also show that the surface topography of both the tool steels and the sheet materials influence on the performance of the lubricants and the galling tendency.   

    When coating a tool steel, the substrate hardness is of greatest importance for the performance and wear of the coating. For the different coatings investigated, the performance of the coatings depends on whether the sheet material is zinc coated or not. However, the CrC/C coating investigated show a good performance with respect to the galling tendency in contact with all of the investigated high strength steel grades.

    List of papers
    1. Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing
    Open this publication in new window or tab >>Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing
    2009 (English)In: Tool09: Tool steels, june 2nd-4th 2009 in aachen, germany, 2009Conference paper, Published paper (Other academic)
    Abstract [en]

    The increasing use of high strength steels in a variety of mechanical engineering applications has illuminated problems associated with galling in sheet metal forming operations. Galling is a tribological phenomenon associated with transfer of material from the steel sheet to the tool surface during forming resulting in seizure of the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number of concepts have been developed in order to reduce the tendency to galling in sheet metal forming, including the development of new dry lubricants, new forming tool steel grades and improved surface engineering treatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potential performance of these concepts in the forming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steel has been evaluated using pin-on disc testing. In the tests, two different lubricants, a dry lubricant and a pre-lube oil, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade, and two different PVD coatings, (Ti,Al)n and CrC/C, were evaluated. Post-test examination of the tribosurfaces using FEG-SEM, EDX and 3D surface profilometry was performed in order to evaluate the mechanisms controlling the material transfer and wear. In summary, the results show that the laboratory testing combined with post-test microscopy and surface analysis give valuable information in order to rank the galling resistance of lubricants, tool steels and PVD-coatings.

    Keywords
    sheet metal forming, high strength steels, galling, dry lubricant, tool steels, PVD-coatings
    National Category
    Metallurgy and Metallic Materials
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-159384 (URN)
    Conference
    Tool09
    Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2012-07-18
    2. Evaluation of galling resistance for some selected combinations of tool steels / stainless steel sheet materials/ lubricants using pin-on-disc testing
    Open this publication in new window or tab >>Evaluation of galling resistance for some selected combinations of tool steels / stainless steel sheet materials/ lubricants using pin-on-disc testing
    2010 (English)In: NordTrib 2010: 14th Nordic Symposium on Tribology, Storforsen, Sweden / [ed] Elisabet Kassfeldt, 2010Conference paper, Published paper (Refereed)
    Abstract [en]

    Stainless steels are well known to be prone to cold welding and material transfer in sliding contacts and therefore difficult to cold form unless certain precautions as discussed in this paper are taken. In the present study different combinations of tool steels/stainless steels/lubricants has been evaluated with respect to their galling resistance using pin-on-disc testing. The results show that a high galling resistance is favored by a high stainless steel sheet hardness and a blasted stainless steel sheet surface topography. The effect of type of lubricant was found to be more complex. For example, the chlorinated lubricants failed to prevent metal-to-metal contact on a brushed sheet surface but succeeded on a blasted sheet surface of the same stainless steel material. This is believed to be due to a protective tribofilm which is able to form on the blasted surface, but not on the brushed surface.

    Keywords
    Galling, stainless steels, cold work tool steels, lubricants
    National Category
    Metallurgy and Metallic Materials
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-159385 (URN)
    Conference
    NordTrib 2010
    Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2016-04-18
    3. Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: Evaluation of galling and wear characteristics against different high strength steels.
    Open this publication in new window or tab >>Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: Evaluation of galling and wear characteristics against different high strength steels.
    2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 16, p. 4045-4051Article in journal (Refereed) Published
    Abstract [en]

    The increasing use of high strength steels in a variety of mechanical engineering applications has illuminatedproblems associated with galling in sheet metal forming operations. Galling is a tribological phenomenonassociated with transfer of material from the steel sheet to the tool surface during forming resulting in seizureof the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number ofconcepts have been developed in order to reduce the tendency of galling in sheet metal forming, including thedevelopment of new dry lubricants, new forming tool steel grades and improved surface engineeringtreatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potentialperformance of three commercial PVD coatings, including CrN, (Ti,Al)N and a CrC/C DLC-based coating, in theforming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steelhas been evaluated using pin-on-disc testing under lubricated contact conditions. Post-test examination ofthe tribosurfaces using FEG-SEM and EDS analyses was performed in order to evaluate the mechanismscontrolling the tendency to material transfer and wear. The results show that in contact with the hot and coldrolled steel the material pick-up tendency of the PVD coatings tend to increase in the order CrC/C–CrN–(Ti,Al)N while in contact with the two galvanized steel sheets, the CrC/C and the (Ti,Al)N coating show a significantlylower material pick-up tendency as compared with the CrN coating. Further, the substrate hardness has astrong influence on the wear of the PVD coatings and consequently on the friction characteristics and gallingtendency of the coating/substrate composite. Low substrate hardness, resulting in a low load bearing capacity,increases the tendency to cracking and subsequently chipping of the brittle coating.

    Keywords
    PVD coatings, tool steel, high strength steel sheet, galling, friction, wear.
    National Category
    Metallurgy and Metallic Materials
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-159386 (URN)10.1016/j.surfcoat.2011.02.053 (DOI)
    Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
  • 41.
    Eriksson, Jenny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Högskolan Dalarna, Materialvetenskap.
    Olsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Evaluation of galling resistance for some selected combinations of tool steels / stainless steel sheet materials/ lubricants using pin-on-disc testing2010In: NordTrib 2010: 14th Nordic Symposium on Tribology, Storforsen, Sweden / [ed] Elisabet Kassfeldt, 2010Conference paper (Refereed)
    Abstract [en]

    Stainless steels are well known to be prone to cold welding and material transfer in sliding contacts and therefore difficult to cold form unless certain precautions as discussed in this paper are taken. In the present study different combinations of tool steels/stainless steels/lubricants has been evaluated with respect to their galling resistance using pin-on-disc testing. The results show that a high galling resistance is favored by a high stainless steel sheet hardness and a blasted stainless steel sheet surface topography. The effect of type of lubricant was found to be more complex. For example, the chlorinated lubricants failed to prevent metal-to-metal contact on a brushed sheet surface but succeeded on a blasted sheet surface of the same stainless steel material. This is believed to be due to a protective tribofilm which is able to form on the blasted surface, but not on the brushed surface.

  • 42.
    Eriksson, Jenny
    et al.
    Högskolan Dalarna, Materialvetenskap.
    Olsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Faculty of Science and Technology.
    Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing2009In: Tool09: Tool steels, june 2nd-4th 2009 in aachen, germany, 2009Conference paper (Other academic)
    Abstract [en]

    The increasing use of high strength steels in a variety of mechanical engineering applications has illuminated problems associated with galling in sheet metal forming operations. Galling is a tribological phenomenon associated with transfer of material from the steel sheet to the tool surface during forming resulting in seizure of the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number of concepts have been developed in order to reduce the tendency to galling in sheet metal forming, including the development of new dry lubricants, new forming tool steel grades and improved surface engineering treatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potential performance of these concepts in the forming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steel has been evaluated using pin-on disc testing. In the tests, two different lubricants, a dry lubricant and a pre-lube oil, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade, and two different PVD coatings, (Ti,Al)n and CrC/C, were evaluated. Post-test examination of the tribosurfaces using FEG-SEM, EDX and 3D surface profilometry was performed in order to evaluate the mechanisms controlling the material transfer and wear. In summary, the results show that the laboratory testing combined with post-test microscopy and surface analysis give valuable information in order to rank the galling resistance of lubricants, tool steels and PVD-coatings.

  • 43.
    Eriksson, Jenny
    et al.
    Högskolan Dalarna, Materialvetenskap.
    Olsson, Mikael
    Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: Evaluation of galling and wear characteristics against different high strength steels.2011In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 16, p. 4045-4051Article in journal (Refereed)
    Abstract [en]

    The increasing use of high strength steels in a variety of mechanical engineering applications has illuminatedproblems associated with galling in sheet metal forming operations. Galling is a tribological phenomenonassociated with transfer of material from the steel sheet to the tool surface during forming resulting in seizureof the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number ofconcepts have been developed in order to reduce the tendency of galling in sheet metal forming, including thedevelopment of new dry lubricants, new forming tool steel grades and improved surface engineeringtreatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potentialperformance of three commercial PVD coatings, including CrN, (Ti,Al)N and a CrC/C DLC-based coating, in theforming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steelhas been evaluated using pin-on-disc testing under lubricated contact conditions. Post-test examination ofthe tribosurfaces using FEG-SEM and EDS analyses was performed in order to evaluate the mechanismscontrolling the tendency to material transfer and wear. The results show that in contact with the hot and coldrolled steel the material pick-up tendency of the PVD coatings tend to increase in the order CrC/C–CrN–(Ti,Al)N while in contact with the two galvanized steel sheets, the CrC/C and the (Ti,Al)N coating show a significantlylower material pick-up tendency as compared with the CrN coating. Further, the substrate hardness has astrong influence on the wear of the PVD coatings and consequently on the friction characteristics and gallingtendency of the coating/substrate composite. Low substrate hardness, resulting in a low load bearing capacity,increases the tendency to cracking and subsequently chipping of the brittle coating.

  • 44.
    Eriksson, Philip
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Evaluation of mechanical and microstructural properties for laser powder-bed fusion 316L2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work was done to get a fundamental knowledge of the mechanical and microstructural properties of 316L stainless steel fabricated with the additive manufacturing technique, laser powder-bed fusion (L-PBF). The aims of the thesis were to study the mechanical and microstructural properties in two different building orientations for samples built in two different machines, and to summarize mechanical data from previous research on additive manufactured 316L.

    Additive manufacturing (AM) or 3D-printing, is a manufacturing technique that in recent years has been adopted by the industry due to the complexity of parts that can be built and the wide range of materials that can be used. This have made it important to understand the behaviour and properties of the material, since the material differs from conventionally produced material. This also adds to 316L, which is an austenitic stainless steel used in corrosive environments.

    To study the effect of the building orientation, samples of 316L were built in different orientations on the build plate. The density and amount of pores were also measured. Tensile testing and Charpy-V testing were made at room temperature. Vickers hardness was also measured. Microstructure and fracture surfaces were examined using light optical microscope (LOM) and scanning electron microscope (SEM).

    The microstructure of the 316L made with L-PBF was found to have meltpools with coarser grains inside them, sometime spanning over several meltpools. Inside these coarser grains was a finer cellular/columnar sub-grain structure. The tensile properties were found to be anisotropic with higher strength values in the orientation perpendicular to the building direction. Also high dense samples had higher tensile properties than low dense samples. The impact toughness was found to be influenced negatively by high porosity. Hardness was similar in different orientations, but lower for less dense samples. Defects due to lack of fusing of particles were found on both the microstructure sample surfaces and fracture surfaces. The values from this study compare well with previous reported research findings.

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  • 45.
    Evertsson, Erica
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Magnetron sputtering of transparent conducting tungsten doped indium oxide2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In thin film solar cells there is a front contact layer called TCO, transparent conducting oxide. This layer requires high conductivity and high transmittance. Different materials such as Tin doped indium oxide (ITO) and Aluminum doped zinc oxide (AZO) are current good alternatives but several other materials are investigated to find even better materials. One of them is tungsten doped indium oxide (IOW). This project was about investigating the deposition process for IOW and characterize the properties of IOW thin film to investigate the possibilities for implementing this material as a contact layer in thin film solar cells. The results from the two batches of depositions varied a lot. Some samples came out dark, but some were transparent and had a high transmittance, suitable for a TCO. The highest transmittance reached through this process was around 95 % in the infrared (IR) range and around 90 % in the visible range. When it comes to the resistivity, no IOW-samples reaches desired levels for a TCO. The lowest resistivity reached was 6.36 * 10-4 W cm. The results showed that the sample with the lowest resistivity was the undoped material, which is contradicting the current theory on the subject. The lowest resistivity for the IOW film was 6.50 * 10-3 W cm. 

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  • 46.
    Fang, Hailiang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Cedervall, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Casado, Francisco Javier Martinez
    Lund Univ, MAX IV Lab, Box 118, S-22100 Lund, Sweden..
    Matej, Zdenek
    Lund Univ, MAX IV Lab, Box 118, S-22100 Lund, Sweden..
    Bednarcik, Jozef
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Ångstrom, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Berastegui, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Insights into formation and stability of tau-MnAlZ(x) (Z = C and B)2017In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 692, p. 198-203Article in journal (Refereed)
    Abstract [en]

    The tau-phase MnAl alloys are promising candidate for rare earth free permanent magnets. In this study, In order to better understand the MnAl epsilon ->tau phase transition mechanism in a continuous cooling process and metastable MnAl tau-phase high temperature stability, Mn0.54Al0.46, Mn0.55Al0.45C0.02 and Mn0.55Al0.45B0.02 alloys were systematically studied by in situ synchrotron X-ray powder diffraction (SR-XRD). The relationship between tau-phase formation tendency and different cooling rates of Mn0.55Al0.45C0.02 was investigated. Besides, the high temperature stabilities of undoped tau-MnAl and carbon/boron doped tau-MnAl were studied. Differential thermal analysis (DTA) was also employed to study the phase transformation as well. The research results show that a high cooling rate of 600 degrees C/min leads to a 50/50 wt% mixture of epsilon- and tau-phase; almost pure tau-phase was obtained when cooled at a moderate cooling rate of 10 degrees C/min; while for a slow cooling rate of 2 degrees C/min, the tau-phase partially decomposed into beta and gamma(2) phases. No intermediate epsilon'-phase was observed during the epsilon ->tau phase transition during the experiments. For the boron and carbon doped tau-MnAl, the 800 degrees C high temperature stability experiments reveal that C stabilizes the tau-MnAl while doped B destabilises the tetragonal structure and it decomposes into beta- and gamma(2)-phases.

  • 47.
    Fors, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Hellgren, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Henriksson, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sirén, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sundström, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Wemlén, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Microcrack Analysis in VBN Components AM Steel Alloy: A microcrack characterisation and origin determination study2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Electron beam additive manufacturing (EBAM) offers a high degree of control over highly complex structures. An EBAM alloy in development by the company VBN Components, specialising in wear-resistant AM steel, has been found to develop microcracks which has been partially characterised in this paper.

    EDS analysis of microcracks in the bulk of the alloy samples has indicated that two carbides congregate in and around the cracks. Thermodynamic simulation of the system in the software Thermo-Calc indicated that the carbides are likely to be MC with V and M6C with Fe, Mo, and W. EBSD analysis was performed, but only a small amount of data was achieved due to difficulties with the sample preparation. From the small amount of data it was still observed that there might be a relation between cracking and large misorientation angles between grains, this however needs more research. Since sufficient sample preparation for EBSD analysis finally was achieved, it is strongly suggested that more samples are prepared according to guidelines presented in this work, so that the correlation between cracking and misorientation angle can be further investigated. Hardness measurements through nanoindentation around cracks proved inconclusive in determining statistically significant differences to hardness in crack-free areas. The overall result of the characterisation indicates both grain orientation and precipitated carbides to be linked with microcracks in the alloy; which should be studied further.

  • 48.
    Fowler, Lee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Janson, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Norgren, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Antibacterial investigation of titanium-copper alloys using luminescent Staphylococcus epidermidis in a direct contact test2019In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 97, p. 707-714Article in journal (Refereed)
    Abstract [en]

    Commercially pure titanium (CP-Ti), used as oral implants, is often populated by various bacterial colonies in the oral cavity. These bacteria can cause Peri-implantitis, leading to loss of bone tissue and failure of implants. With the increased awareness of antibiotic resistance, research has been directed towards alternative solutions and recent findings have indicated titanium-copper (Ti-Cu) alloys as a promising antibacterial material. The aim of this study was to produce homogeneous Ti-Cu alloys, with various concentrations of copper, and to characterise their antibacterial properties through direct contact tests, using luminescent bacteria, in addition to traditional materials characterisation techniques. Samples of CP-Ti and four different Ti-Cu alloys (1, 2.5, 3 and 10 wt%Cu) were produced in an arc-furnace, heated treated and rapidly quenched. X-ray diffraction revealed that Ti2Cu, was present only in the 10 wt%Cu alloy, however, scanning electron microscopy (SEM) indicated precipitates at the grain boundaries of the 3 wt%Cu alloy, which were confirmed to be of a copper rich phase by energy dispersive x-ray spectroscopy (EDS) analysis. EDS line scans confirmed that the alloys were homogenous. After 6 h, a trend between copper content and antibacterial rate could be observed, with the 10 wt%Cu alloy having the highest rate. SEM confirmed fewer bacteria on the 3 wt%Cu and especially the 10 wt%Cu samples. Although the 10 wt%Cu alloy gave the best antibacterial results, it is desired that the Cu concentration is below similar to 3 wt%Cu to maintain similar mechanical and corrosive performance as CP-Ti. Therefore, it is proposed that future work focuses on the 3 wt%Cu alloy.

  • 49.
    Fredriksson, Mikael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Uppsala university.
    Åkerlund, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Åberg, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Österberg, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Havo, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    High Performance Steel for Percussive Drilling2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Atlas Copco Secoroc AB are searching after new bulk materials for drill heads that are used in percussive drilling in order to improve their strength and durability. The aim of this project is to assist Atlas Copco in this search and provide them with further information regarding material properties, alloying elements, suppliers, etc.

    A literary study was carried out in order to identify materials that had UTS and KIC more than or equal to 1700 MPa and 70 MPa*m^1/2, respectively. Materials that fulfilled these criteria were T250 grade maraging steel, Cobalt free maraging steel, High cobalt maraging steel, 300 grade maraging steel, AerMet 100, AF1410, S53, M54, 300M, 4340M and PremoMet. These were categorized into maraging steels, high alloy secondary hardened steels, and low alloy steels, and were then further researched.

    The material with the highest combination of UTS and KIC was M54 followed by AerMet 100; while AF1410 had the highest KIC but a low UTS, and PremoMet had the highest UTS but a low KIC. Maraging steels and HASH steels have a similar price range, while low alloy steels are much cheaper.

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  • 50.
    Fritze, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Koller, Christian M.
    TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria.
    von Fieandt, Linus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Malinovskis, Paulius
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Johansson, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mayrhofer, Paul H.
    TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Influence of Deposition Temperature on the Phase Evolution of HfNbTiVZr High-Entropy Thin Films2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 4, article id 587Article in journal (Refereed)
    Abstract [en]

    In this study, we show that the phase formation of HfNbTiVZr high-entropy thin films is strongly influenced by the substrate temperature. Films deposited at room temperature exhibit an amorphous microstructure and are 6.5 GPa hard. With increasing substrate temperature (room temperature to 275 degrees C), a transition from an amorphous to a single-phased body-centred cubic (bcc) solid solution occurs, resulting in a hardness increase to 7.9 GPa. A higher deposition temperature (450 degrees C) leads to the formation of C14 or C15 Laves phase precipitates in the bcc matrix and a further enhancement of mechanical properties with a peak hardness value of 9.2 GPa. These results also show that thin films follow different phase formation pathways compared to HfNbTiVZr bulk alloys.

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