合金
材料科学
亚稳态
无扩散变换
高熵合金
六方晶系
热力学
等球密排
固溶体
组态熵
结晶学
马氏体
冶金
化学
微观结构
物理
有机化学
作者
Cameron L. Tracy,Sulgiye Park,Dylan Rittman,S.J. Zinkle,Hongbin Bei,Maik Lang,Rodney C. Ewing,Wendy L. Mao
摘要
High-entropy alloys, near-equiatomic solid solutions of five or more elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys exhibiting only face- or body-centered cubic structures. Here, we report the high-pressure synthesis of a hexagonal close-packed phase of the prototypical high-entropy alloy CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial fcc structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the transformation is sluggish, occurring over a range of >40 GPa. However, the behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This demonstrates a means of tuning the structures and properties of high-entropy alloys in a manner not achievable by conventional processing techniques.
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