Microstructure, phase stability and properties of CoCr0.5CuxFeyMoNi compositionally complex alloys

Liquid-phase separation occurred in CoCrCuxFeMoNi (x >= 0.5) alloys when the mixing entropies are positive in our previous work. So in this work, CoCr0.5CuxFeyMoNi alloys are designed to investigate the microstructure, component phases and properties. FCC and BCC were detected in CoCr0.5CuxFeyMoNi alloys, accompanied with a topologically close-packed phase. A parameter, V-R, was defined, where V-R is the ratio of the volume fraction of BCC plus phases and that of FCC phase. The maximum strength and the ductility were obtained at the minimum V-R of the alloys, whereas the hardness increased with the increasing V-R. It can be presumed that the strange balance between strength, ductility and hardness is an indirect result of the degree of brittle failure.