Temperature- and strain-dependent thermally-activated deformation mechanism of a ferrous medium-entropy alloy

In this study, quasi-static tensile properties of Fe₆₀Co₁₅Ni₁₅Cr₁₀ (at%) ferrous medium-entropy alloy at 298 K and 77 K were investigated in terms of thermally-activated deformation mechanism. Relatively high strain rate sensitivity and low activation volume were estimated using strain rate jump tests at 77 K where deformation-induced martensitic transformation took place, compared to those at 298 K. Different rate-controlling mechanisms were identified for early and latter deformation at both temperatures considering the plastic strain. Dislocation behaviors, e.g., cross-slip or dislocation accumulation, based on the thermally-activated deformation mechanism, support the outstanding cryogenic tensile properties of the present alloy.