Achieving excellent strength and ductility of Ti2ZrNbHfVx refractory high-entropy alloys by V addition

Refractory high-entropy alloys (RHEAs) have gained considerable attention owing to their excellent mechanical properties. In this study, the combined effects of vanadium (V) on the microstructure, mechanical properties, and strengthening mechanism of Ti2ZrNbHfVx (x = 0, 0.2, 0.4, 0.6, 0.8, and 1, respectively) are investigated. The results indicate that all Ti2ZrNbHfVx alloys present a BCC single phase with a typical dendritic microstructure. The yield strength (YS) increase with the increasing V content. Among them, the Ti2ZrNbHfV RHEA has a YS of up to 1008 MPa, a compressive strain of >50%, and a specific yield strength (SYS) of 134.20 KPa·m3·kg−1. Furthermore, the Vickers hardness increases from 230.23 to 328.80 HV. High YS is mainly derived from solid-solution and fine-grain strengthening. The YS of Ti2ZrNbHfVx RHEAs is mostly obtained from atomic radius and shear modulus misfits, according to the solution strengthening model. The present study provides not only a solution for achieving a strength-ductility synergy but also insights into the development of RHEAs with excellent mechanical properties.