The Influence of Mo and Y on the Microstructure and Properties of TiZrHfNb Series Refractory High-Entropy Alloys

TiZrHfNbMo refractory high-entropy alloy has poor plasticity and a relatively high density at room temperature, which limits its wide industrial application. To develop RHEAs featuring a simple structure, low density, and excellent overall performance. In this study, three refractory high-entropy alloys of Ti22Zr25Hf(35−x)Nb18Mox (x = 10, 15, 20) were preliminarily designed, and the effects of different Mo contents on their microstructure and properties were investigated. All three components are of a single-phase BCC structure. Room-temperature and high-temperature compression and friction wear tests show that, with the increase in Mo, the solid solution strengthening effect is enhanced. The room temperature yield strength increases by 35.1%, the high-temperature yield strength increases by 227.5%, and the wear rate decreases by 60.5%. However, the room temperature fracture strain of Mo20 is reduced to 24%. Therefore, Y was introduced into the Mo20 refractory high-entropy alloy at mass fractions of 0.1% and 0.2% to further enhance its plasticity. The experimental results show that the addition of Y, through grain refinement and solid solution strengthening, simultaneously enhances room-temperature plasticity (from 24% to 32%) and wear resistance. The findings furnish a theoretical framework for rational element selection in RHEAs design.