Deformation behavior of a Co-Cr-Fe-Ni-Mo medium-entropy alloy at extremely low temperatures

Jongun Moon, Elena Tabachnikova, Sergii Shumilin, Tetiana Hryhorova, Yuri Estrin, Jamieson Brechtl, Peter K. Liaw, Wenqing Wang, Karin A. Dahmen, Alireza Zargaran, Jae Wung Bae, Hyeon Seok Do, Byeong Joo Lee, Hyoung Seop Kim

Research output: Contribution to journalArticlepeer-review

Abstract

We report the mechanical and microstructural characteristics of a medium-entropy alloy, Co17.5Cr12.5Fe55Ni10Mo5 (atomic percent, at%) at cryogenic temperatures, down to a record low temperature of 0.5 K. The alloy exhibits excellent strength and ductility combined with a high strain-hardening rate in the entire temperature range investigated. Its property profile, including the yield strength, ultimate tensile strength, strain hardening capability, and absorbed mechanical energy, is better than those of most alloys and HEAs used in cryogenics. Within the interval of extremely low temperatures considered (0.5–4.2 K), the alloy exhibits several unusual features, including anomalies of the temperature dependence of the yield strength and tensile ductility, discontinuous plastic deformation (DPF), and a change in the propensity for the deformation-induced martensitic transformation. While the occurrence of these effects in the same temperature interval may be fortuitous, we hypothesize that they are interrelated and provide a tentative explanation of the observed phenomena on this basis.

Original languageEnglish (US)
Pages (from-to)55-68
Number of pages14
JournalMaterials Today
Volume50
DOIs
StatePublished - Nov 2021

Keywords

  • Cryogenic temperatures
  • Discontinuous plastic deformation
  • Dislocation
  • Martensitic phase transformation
  • Medium-entropy alloy

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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