Temperature dependence of mechanical and thermodynamic properties of Ti(25+x)Zr25Nb25Ta(25-x) (x < 20) refractory high entropy alloys: Influences of substitution of Ti for Ta

摘要

Temperature dependence of mechanical and thermodynamic properties of refractory high entropy alloys Ti(25+x)Zr25Nb25Ta(25-x) (x < 20) are studied from ab initio quasi-harmonic Debye-Gr?neisen model, and the influences of substitution of Ti for Ta are emphasized. The substitution of Ti for Ta results in the significantly reduced densities and the apparently enhanced specific elastic properties of Ti(25+x)Zr25Nb25Ta(25-x) alloys. Moreover, the increases of Ti content obviously improves ductility. At high temperature, the alloys with higher Ti content demonstrate the stronger thermal expansion behavior and thermal conductivity. Importantly, the alloys with higher Ti content possess the greater specific elastic properties at high temperature. Especially, in the studied temperature range, the present alloys exhibit good anti-softening ability based on temperaturedependent mechanical properties. Therefore, the replacement of Ta by Ti in refractory Ti(25+x)Zr25Nb25Ta(25-x) alloys is beneficial for formation of novel high temperature light-weight structural materials with lower density, better ductility and higher specific mechanical properties.