Interstitial engineering enabling superior mechanical properties of nitrogen-supersaturated Fe₅₀Mn₃₀Co₁₀Cr₁₀ high-entropy alloys
Date
2024
Authors
Chen, Y.
Ma, J.
Lin, Y.
Hora, Y.
Zhou, Z.
Slattery, A.
An, X.
Xie, Z.
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Advisors
Journal Title
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Journal article
Citation
Acta Materialia, 2024; 277:120214-1-120214-13
Statement of Responsibility
Yujie Chen, Jisheng Ma, Yuecheng Lin, Yvonne Hora, Zhifeng Zhou, Ashley Slattery, Xianghai An, Zonghan Xie
Conference Name
Abstract
Interstitial atoms are key in modifying microstructures and enhancing mechanical properties of metals. Traditionally, the introduction of interstitial elements into metal matrices has been limited to low levels (< 2 at.%) to avoid the formation of brittle ceramics, constraining the exploitation of their full strengthening potential. This study introduces nitrogen-supersaturated high-entropy alloys (HEAs) with up to 28.9 at.% nitrogen, achieving substantial interstitial strengthening and phase adjustment. Remarkably, these HEAs remain solid solution phases without nitride formation, even at exceptionally high nitrogen levels. The microstructural evolution with increasing nitrogen content transitions from a single face-centred cubic (FCC) structure to a dual-phase structure of FCC and hexagonal close-packed (HCP) phases, and ultimately reverts to a predominantly FCC structure. These alloys achieve an impressive hardness of ~ 20 GPa, comparable to ceramics, while maintaining exceptional damage-tolerance and plasticity. The outstanding mechanical properties are attributed to massive solid solution strengthening from a high nitrogen level, a hierarchical dual-phase structure, and stress-induced phase transformation from FCC to HCP. Contrary to the brittleness typical of nitrides, these nitrogen-supersaturated HEAs exhibit substantial plastic deformation akin to metallic materials, thus opening up a new pathway for enhancing the mechanical performance of advanced alloys under extreme loading conditions.
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Available online 22 July 2024
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© 2024 Published by Elsevier Ltd on behalf of Acta Materialia Inc.