First-principles Study on Effect of Pressure and Temperature on Mechanical, Thermodynamic Properties, and Electronic Structure of Ni3Al Alloy

The influence of temperature and pressure on the electronic, elastic, structural, and thermodynamic properties of Ni₃Al alloy was investigated by performing a first-principles study. The calculated elastic constants, equilibrium lattice constants, and elastic modulus agree well with the recorded theoretical and experimental data. The calculated elastic constants indicate that C₁₁ is more sensitive than C₁₂ and C₄₄ to pressure. The Young’s modulus, bulk modulus, and shear modulus increase with the increase of pressure. The ratio of bulk to shear modulus (B/G) and anisotropy factor A were also analyzed. The Debye temperature was obtained by calculating the elastic constants, and it changes with the change in the pressure. The thermal expansion coefficient, normalized volume, heat capacity, bulk modulus, and Debye temperature Θ_D were determined and analyzed using the quasi-harmonic Debye model at pressures of 0∼60 GPa and temperatures of 0∼1600 K. Finally, the density of states and Mulliken population were investigated and the effect of pressure on these was analyzed.