Ab initio calculations of elastic constants and thermodynamic properties of γTiAl under high pressures

We have investigated the structural and elastic properties of γTiAl under high pressures using Vanderbilt-type ultrasoft pseudopotentials within the generalized gradient approximation correction (GGA) in the frame of density functional theory. The calculated pressure dependence of the normalized volume is in excellent agreement with the experimental results. The elastic constants and anisotropy as a function of applied pressure, the ratio of the normalized lattice parameters (a − a0)/a0, (c − c0)/c0 and the normalized volume (V − V0)/V0 with the applied pressure are presented. The variations of bulk modulus Ba, Bc, and the brittleness with the pressure are investigated. Through the quasi-harmonic Debye model, we also study the thermodynamic properties of γTiAl. The thermal expansion versus temperature and pressure, the thermodynamic parameters X (X: Debye temperature or specific heat) with pressure P, and the heat capacity of γTiAl at various pressures and temperatures are estimated.