Influences of recrystallisation and σ phase precipitation on the mechanical properties of CoFeNiMnV high-entropy alloy

An equiatomic CoFeNiMnV high-entropy alloy with a face-centred cubic phase was cast and cold-rolled. The influence of recrystallisation and σ phase precipitation on the mechanical properties of this alloy was explored by varying the annealing temperature from 700 to 1000 °C. The results revealed that V is more effective than Cr at stabilising the σ phase. The precipitation of σ phase occurred before recrystallisation during the annealing process. The σ phase precipitation strengthening and recrystallisation softening had a combined effect on mechanical behaviour. The strength decreased with increasing annealing temperature, resulting from an increased recrystallisation percentage. Moreover, a heterogeneous structure with partial recrystallisation resulted in back stress hardening, and the precipitated σ-phase promoted crack nucleation, resulting in premature fracture.