The influence of refractory metals on the elastic modulus, elastic anisotropy and thermodynamic properties of ZrAl2 high-temperature alloy

To improve the mechanical and thermodynamic properties of ZrAl2 high-temperature alloy, the influence of refractory metals on the structural stability, elastic modulus, elastic anisotropy and thermodynamic properties of the hexagonal ZrAl2 high-temperature alloy is studied by the first-principles calculations. The calculated results show that three refractory metal-doped ZrAl2 alloys are stability at the ground state. Importantly, it is found that these refractory metals enhance the bulk modulus of ZrAl2 because the introduction of refractory metal improves the localized hybridization between Zr atom and Al atom. The calculated bulk modulus follows the sequence of W-doping>Mo-doping>Hf-doping>ZrAl2. In addition, the parent ZrAl2 shows smallest shear anisotropy along the (001) plane. However, the W-doped and Mo-doped ZrAl2 alloys show the isotropic. Furthermore, it is found that these refractory metals enhance the melting point and Debye temperature of ZrAl2. Here, the calculated melting point and Debye temperature of the W-doped ZrAl2 are much higher than the parent ZrAl2. Therefore, we believe that the W element is an effective metal to improve the overall properties (such as elastic modulus, elastic anisotropic and thermodynamic properties) of ZrAl2 high-temperature alloy.