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arXiv · 1611.00876

High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi

Cameron L. Tracy·Sulgiye Park·Dylan R. Rittman·Steven J. Zinkle·Hongbin Bei·Maik Lang·Rodney C. Ewing·Wendy L. Mao
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Abstract

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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Cameron L. Tracy, Sulgiye Park, Dylan R. Rittman, Steven J. Zinkle, Hongbin Bei, Maik Lang, Rodney C. Ewing, Wendy L. Mao. 2016-11-03. High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi. https://doi.org/10.1038/ncomms15634

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