Deformation mechanism of a high-entropy alloy CoCrFeMnNi at intermediate high temperatures investigated by stress relaxation

Abstract

Stress relaxation tests were conducted on a high entropy alloy CoCrFeMnNi at 873 K, 973 K and 1073 K. The relaxation increased with rising temperature and serrated flow occurred at 973 K. Two parameters, activation volume and activation energy, were extracted: 12, 31 and 62 b3 (b = 0.255 nm, is the Burgers vector of the alloy) for activation volume and 0.1, 0.3 and 0.7 eV for activation energy with ascending temperature. The magnitude of activation volume and energy plus the occurrence of serrated flow at a critical temperature indicate that the dislocation glide mediated by impurity atoms is the likely mechanism for deformation at intermediate temperatures.