Achieving high ductility at medium temperature in a nonequiatomic CoCrNi alloy

The tensile strength and ductility of face-centered cubic (FCC) multi-principal element alloys (MPEAs) typically decline monotonically with increasing temperature. In this work, we conducted tensile tests at different temperatures and characterized deformation microstructures for a nonequiatomic CoCrNi alloy with low stacking fault energy (SFE). Exceptional ductility is obtained at medium temperature, breaking the general sense of monotonic change with temperature. The effect of deformation mechanisms of dislocations, stacking faults and phase transformation on the ductility was discussed. This work reveals the unique temperature effect on the mechanical properties of metals with very low SFE.