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2023 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 33, no 51, article id 2307897Article in journal (Refereed) Published
Abstract [en]
This study provides principles for designing new corrosion resistant high entropy alloys. The theoretical framework is a percolation model developed by Newman and Sieradzki that predicts the ability of an alloy to passivate, i.e., to form a protective surface oxide, based on its composition. Here, their model is applied to more complex materials than previously, namely amorphous CrFeNiTa and CrFeNiW alloys. Furthermore, the model describes a more complex passivation process: reforming the oxide layer above the transpassive potential of Cr. The model is used to predict the lowest concentration of Ta or W required to extend the passive region, yielding 11–14 at% Ta and 14–17 at% W. For CrFeNiTa, experiments reveal a threshold value of 13–15 at% Ta, which agrees with the prediction. For CrFeNiW, the experimentally determined threshold value is 37–45 at% W, far above the predicted value. Further investigations explore why the percolation model fails to describe the CrFeNiW system; key factors are the higher nobility and the pH sensitivity of W. These results demonstrate some limitations of the percolation model and offer complementary passivation criteria, while providing a design route for combining the properties of the 3d transition metal and refractory metal groups.
Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2023
Keywords
corrosion, thin film, coating, high entropy alloy, percolation theory
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-489915 (URN)10.1002/adfm.202307897 (DOI)001062551700001 ()
Funder
Vinnova, 2016-05156Swedish Research Council, 2019-00207Swedish Foundation for Strategic Research, ARC19-0026Knowledge Foundation
Note
Title in the list of papers of León Zendejas Medina's thesis: Extending the passive region of CrFeNi-based high entropy alloys by including Ta or W
2022-12-062022-12-062024-05-21Bibliographically approved