Elucidating the transition of cryogenic deformation mechanism of CrMnFeCoNi high entropy alloy.

• CrMnFeCoNi HEA exhibits excellent mechanical properties at cryogenic temperatures. • Enhanced yield strength of the alloy stems from the larger lattice distortion. • High dislocation density and nano-twins lead to the high SHR. • Lower deformation temperature pronouncedly decreased SFE. Here, the evolution of the deformation mechanism of the well-known CrMnFeCoNi high entropy alloy (HEA) under a cryogenic temperature was investigated via using transmission electron microscopy characterization after compressive experiments. It is found that, in contrast to the dominate mechanism of dislocation slip at 298 K, the deformation mode of the studied HEA at 123 K can be divided into two stages: (i) at the initial plastic stage, the plasticity is mainly induced by the planar dislocation glide; and (ii) at the late plastic stage, the combination of dislocation hardening and mechanical twinning facilitates high strength for the studied alloy. These findings are helpful to understand the temperature dependent deformation mechanism of high entropy alloys. [ABSTRACT FROM AUTHOR]