Cryogenic-deformation-induced phase transformation in an FeCoCrNi high-entropy alloy

Abstract

An FeCoCrNi high-entropy alloy (HEA) was deformed at ambient temperature and cryogenic temperatures down to 4.2 K. Phase transformation from a face-centered cubic (FCC) structure to a hexagonal close-packed (HCP) structure occurred during cryogenic deformation. Lowering the temperature promotes the transformation. Atomic-scale structural characterisation suggested that the formation of the HCP structure was achieved via the glide of Shockley partial dislocations on every other $ {\{ 111\} _{{\rm FCC}}} $ plane. Due to the kinetic limitation, the occurrence of this transformation was limited even though theoretical investigations predicted lower free energy of the HCP phase than that of the FCC phase in the HEA.

Keywords

• High-entropy alloy
• phase transformation
• cryogenic temperature
• shockley partial dislocations