Design of directly cast Ni49Fe20Al17V6Co4Cr4 eutectic high-entropy alloy with outstanding mechanical performance

Abstract

A novel non-equiatomic Ni49Fe20Al17V6Co4Cr4 eutectic high-entropy alloy (EHEA) with alternating soft FCC/L12 and hard B2 nanolamellae was prepared by directly cast method. The as-cast Ni49Fe20Al17V6Co4Cr4 EHEA exhibits a superior strength-ductility synergy that far outperforms that of some reported as-cast EHEAs. In particular, the as-cast Ni49Fe20Al17V6Co4Cr4 EHEA shows a high yield strength of 770 MPa, a high tensile strength of 1208 MPa as well as a fracture strain of 15.7 %, respectively. Such an exceptional mechanical property is mainly due to the extensive dislocation activities in both FCC/L12 and B2 nanolamellae. Concretely, the high strength of the as-cast Ni49Fe20Al17V6Co4Cr4 EHEA derives from not only the interface strengthening of ultrafine lamellae soft FCC/L12 and hard B2 phases, but also the hindering of dislocation slipping by ordered L12 nanoprecipitates. The FCC and B2 phases present a stable K–S orientation relationship, which further endows the as-cast EHEA with exceptional strength-ductility combination. The designed Ni49Fe20Al17V6Co4Cr4 EHEA by directly casting provides a promising potential for the widespread engineering applications in the future.