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Deposition and characterization of ternary thin films within the Ti–Al–C system by DC magnetron sputtering
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
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2006 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 291, no 1, 290-300 p.Article in journal (Refereed) Published
Abstract [en]

The formation of ternary compounds within the Ti–Al–C system was studied by magnetron sputtering for thin-film deposition and first-principles calculations for phase stability. As-deposited films were characterized with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM). The hardness and Young's moduli of the material were studied by nanoindentation. Epitaxial and phase-pure films of Mn+1AXn phases Ti3AlC2 and Ti2AlC as well as the perovskite phase Ti3AlC were deposited on Al2O3(00ℓ) wafers kept at temperatures between 800 and 900 °C. The only ternary phases observed at low temperatures (300 °C) were Ti3AlC and cubic (Ti,Al)C, the latter can be described as a metastable solid solution of Al in TiC similar to the more studied (Ti,Al)N system. The difficulties to form MAX phases at low substrate temperatures were attributed of requirement for a sufficient diffusivity to partition the elements corresponding to the relatively complex crystal structures with long c-axes. While MAX-phase synthesis at 800 °C is significantly lower than contemporary bulk sintering processes, a reduction of the substrate temperature towards 300 °C in the present thin-film deposition experiments resulted in stacking sequence variations and the intergrowth of (Ti,Al)C.

Place, publisher, year, edition, pages
2006. Vol. 291, no 1, 290-300 p.
Keyword [en]
Solid solutions, PVD, Carbides, MAX-phase, Perovksite
National Category
Inorganic Chemistry
URN: urn:nbn:se:uu:diva-96302DOI: 10.1016/j.jcrysgro.2006.03.008OAI: oai:DiVA.org:uu-96302DiVA: diva2:170833
Available from: 2007-10-19 Created: 2007-10-19 Last updated: 2014-05-14Bibliographically approved
In thesis
1. Synthesis and Characterization of Ternary Carbide Thin Films
Open this publication in new window or tab >>Synthesis and Characterization of Ternary Carbide Thin Films
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis reports on synthesis, microstructure and properties of binary and ternary carbide thin films deposited by dc magnetron sputtering. These materials are interesting since they exhibit a wide range of useful properties, such as high hardness, resistance to wear and oxidation, and high electrical conductivity. Here, an early transition metal (M) and carbon (C) have been used as the basis, often with the addition of a second M-element or an A-group element (A). In these systems nanocomposites, metastable solid solutions, multilayers, or Mn+1AXn-phases have been deposited. The Mn+1AXn-phases are a group of nanolaminated compounds with a unique mixture of metallic and ceramic properties. In general X is carbon or nitrogen, although here only carbon has been used.

Epitaxial MAX-phase thin films of Ti2AlC, Ti3AlC2 and V2GeC have been deposited for the first time. They have been studied with emphasis on phase stability, phase composition and nucleation characteristics to gain deeper insights into their growth. The microstructure of the films was characterized by electron microscopy and X-ray diffraction. In addition, bond strength characteristics have been studied by soft X-ray spectroscopy and complementary calculations within DFT. Their mechanical and electrical properties have been studied, and the results are discussed on the basis of their electronic structure. Furthermore, by interleaving the Ti3SiC2 MAX-phase with TiC0.67 a multilayer structure has been formed, for which a new intrusion-type deformation behaviour has been described.

A new concept in the design of nanocomposite films has been developed, whereby a solid solution of a weak carbide-forming element in the carbide structure creates a driving force for surface segregation of C. This concept has been verified both theoretically and experimentally for the Ti-Al-C and Ti-Fe-C systems. It has been shown by pin-on-disc measurements that this surface segregation leads to graphitization and consequently a very low friction coefficient for these films. Finally, it has been demonstrated that low-friction films with tunable magnetic properties can be achieved in the Ti-Fe-C system.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 62 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 353
Chemistry, Thin film, dc magnetron sputtering, tribology, carbide, PVD, MAX-phase, DFT, solid solution, Kemi
urn:nbn:se:uu:diva-8265 (URN)978-91-554-6991-7 (ISBN)
Public defence
2007-11-09, Häggsalen, Ångström Laboratory, Lägerhyddsvägen 1, 751 21, Uppsala, 10:15
Available from: 2007-10-19 Created: 2007-10-19 Last updated: 2010-09-13Bibliographically approved

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