Superplastic-like flow in a fine-grained equiatomic CoCrFeMnNi high-entropy alloy

A CoCrFeMnNi high-entropy alloy (HEA) showed elongation to failure ∼320% at T = 1023 K and a strain rate . Strain hardening and texture weakening occurred at low , whereas flow softening and texture strengthening were observed at high experiments. The strain rate sensitivity (m) decreased from 0.5 to ∼0.25 with increasing . Deformation with m∼0.5 and deformation-enhanced grain growth at low indicated superplasticity associated with grain boundary sliding. The grain boundary diffusion coefficient diminished by a factor of ∼4 in the HEA. Concurrent nucleation, growth and cavity interlinkage caused premature failure compared with conventional superplastic alloys.