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ASTM F1058 Co–22Cr–17Fe–15Ni–4Mo (mol%) alloys (equivalent to Co–20Cr–16Fe–15Ni–7Mo in mass%) are widely used in biomedical applications, particularly in balloon-expandable stents, which require a combination of high ultimate tensile strength (UTS), good ductility, and low 0.2 % proof strength. To optimize the mechanical properties of these alloys, it is essential to understand their plastic deformation behavior. In this study, first-principles calculations, microstructural analysis, and mechanical property evaluation were used to investigate the stacking fault energy (SFE) and plastic deformation behavior of these alloys as a function of their Ni and Fe content. First-principles calculations indicated that their SFE increased with increasing Ni and Fe content, with Ni influencing the SFE more than Fe. Experimentally, increasing the Ni content suppressed the γ-to-ε stress-induced martensitic transformation during plastic deformation, resulting in improved ductility without compromising strength. With increasing Ni content, the plastic deformation mechanism in the early stage changed from martensitic transformation and/or deformation twinning to dislocation slip, attributable to an increase in the SFE. This study indicates that SFE evaluation by first-principles calculations is an effective approach for designing Co–Cr-based multicomponent systems from the perspective of plastic deformation mechanisms.

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• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

Keyword: Co–Cr alloy, High entropy alloy, Biomedical, Stacking fault energy, First-principles calculation, Special quasi-random structure, Mechanical properties

Date published: 2025-09-22

Publisher: Elsevier BV

Journal:

• Journal of Alloys and Compounds (ISSN: 09258388) vol. 1042 183927

Funding:

• National Institute for Materials Science 2025-014
• Japan Society for the Promotion of Science 24K01149

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1016/j.jallcom.2025.183927

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Updated at: 2025-12-02 12:30:12 +0900

Published on MDR: 2025-12-02 12:24:11 +0900