Predicting the elastic anisotropy, thermal conductivity and tensile properties of Hf₂AlX (X = N and C) by the first-principle calculation

This study uses first-principles calculations to investigate the structure, elastic properties, electronic properties, thermal conductivities, and tensile properties of Hf₂AlN and Hf₂AlC. Moreover, this work calculates the anisotropies of the thermal conductivities and elastic moduli of Hf₂AlN and Hf₂AlC; the results show that the elastic moduli of Hf₂AlN and Hf₂AlC have obvious anisotropy. In addition, the hardness, Poisson's ratios, sound velocities, and Debye temperatures were also calculated from the elastic constants. The calculated electronic properties show that Hf₂AlN and Hf₂AlC are covalently bonded. Clarke's and Cahill's models were utilized to compare the minimal thermal conductivities of Hf2AlN and Hf2AlC. Finally, the dynamic stability was demonstrated by analyzing phonon dispersion curves and state density. Based on simulated tensile tests, it is concluded that Hf₂AlC and Hf₂AlN have higher tensile strength in [110] direction than in [001] direction.