The Microstructure and Mechanical Properties of Refractory High-Entropy Alloys with High Plasticity

Refractory high-entropy alloys (RHEAs) are promising materials used at high temperature, but their low plasticity restricts their application. Based on the valence electron concentration (VEC) principle, four kinds of RHEAs (ZrTiHfV(0.5)Nb(0.5), Zr(2.0)TiHfVNb(2.0), ZrTiHfNb(0.5)Mo(0.5), and ZrTiHfNb(0.5)Ta(0.5)) are designed (VEC < 4.5). The experimental results show that the plasticity of these alloys was greatly improved: the static compressive strain was higher than 50% at room temperature (RT), and some elongations were produced in the tensile process. Moreover, the microstructure and phase composition are discussed in detail. The addition of Nb, Mo, and Ta contributed to the high-temperature strength. Finally, the dynamic mechanical properties of these RHEAs with coordination between strength and plasticity are investigated.