Refractory high entropy alloy with ductile intermetallic B2 matrix / hard bcc particles and exceptional strain hardening capacity

Abstract

In this study, a new Nb30Mo30Hf20Co20 (at. %) refractory high entropy alloy (RHEA) comprising an intermetallic (Hf, Co)-rich B2 matrix and disordered (Nb, Mo)-rich bcc particles was introduced. The B2 matrix showed relatively high dislocation mobility, which, coupled with its continuity, allowed bridging and blunting of the cracks formed in the hard bcc particles during plastic deformation. The complex deformation behavior of the constitutive phases resulted in extraordinary high strain hardening capacity at 22–600 °C, exceeding single- and multi-phase RHEAs, together with the high strength. Our work endows new opportunities to develop high-performance alloys for high-temperature applications.