Enhanced strength and ductility in a brittle hypoeutectic high-entropy alloy via spheroidizing annealing

Abstract

Eutectic high-entropy alloys (EHEAs), combining the advantages of traditional eutectic alloys and high-entropy alloys (HEAs), have become a promising multi-principal alloy system for industrial application. Further improving the strength-ductility of EHEAs has been the pursuit of researchers. In this work, we found that the strength and ductility can be improved simultaneously in a new class EHEAs with serrated eutectic structure via simple spheroidizing annealing. As a manifestation of this fascinating discovery, an Al0.25CoCrFeNi2V0.8B0.4 EHEA was developed that was composed of face-centered cubic (FCC) and serrated boride phase and then subjected to spheroidizing annealing. The ultimate tensile strength (UTS) and elongation (EL) increased from 1193 MPa, 4.3 % (in as-cast) to 1410 MPa, 15.7 % after spheroidizing annealing. This combined increase in strength and ductility was attributed to that the serrated boride eutectic phase is spheroidized into a dispersed spherical eutectic phase, which effectively alleviates the stress concentration and provides more space for dislocation slip, promoting strain-hardening ability during deformation. This work provides valuable insight into the development of high-performance EHEAs.