Recrystallization and mechanical behavior of Co40(CrFeNi)60 medium-entropy alloy

•Co40(CrFeNi)60 was studied after cold rolling and annealing at 600 °C for 15 min, 1 h and 10 h.•Annealing for 15 min results in partial recrystallization with fRX = 45 %.•The yield strength in this annealed condition is 875 MPa and ductility is 30 %.•This strength-ductility combination is better than for the other Co40(CrFeNi)60 samples.•This combination is also better than that for CoCrFeNi annealed at 600 °C for 15 min. The evolution of the microstructure and mechanical properties during annealing has been investigated in an 80 % cold-rolled Co40(CrFeNi)60 medium-entropy alloy. It is found that the as-rolled material exhibits a heterogeneous microstructure containing deformation twins, low misorientation bands and shear bands. This material has a yield strength of 1239 MPa and ductility of 12 %. Partial recrystallization during annealing at 600 °C for 15 min results in a good combination of a yield strength of 875 MPa and ductility improved to 30 %. The strength, ductility and work-hardening capacity for this sample are greater than those for a CoCrFeNi alloy after the same thermomechanical treatment. The improved mechanical performance of the Co40(CrFeNi)60 alloy is attributed to a greater propensity for deformation twinning caused by a reduced stacking fault energy of this material.