Formation of core–shell structure in immiscible CoCrCuFe_1.5Ni_0.5 high-entropy alloy

The microstructure evolution and properties of CoCrCuFe_1.5Ni_0.5 high-entropy alloy solidified at different undercoolings (ΔT) have been investigated by using cyclic superheating technique. Results show that this alloy exhibits typical liquid phase separation (LPS) behavior and the core–shell structure can be attained at tiny undercooling, e.g., ΔT = 43 K. Ulteriorly, the large variation distribution of Cu-rich phase in core area certified second LPS has taken place when undercooling is above 140 K. The hardness of alloy in Cu-lean core phase increases greatly from 165 HV to 219 HV owing to the refined grain with the increasing undercooling. The results provide a method to regulate the morphologic structures and mechanical properties of the immiscible CoCrCuFe_1.5Ni_0.5 HEA.