Structural, elastic and thermodynamic properties of the binary precipitates γ-TiAl, DO22-Al3Ti and α2-Ti3Al

The pressure dependence of the lattice and elastic constants of the binary precipitates γ-TiAl, DO22-Al3Ti and α2-Ti3Al are firstly investigated by using a first-principles approach. The calculated results at 0 GPa and 0 K agree well with the existing experimental and other theoretical values. Using the density-functional perturbation theory (DFPT) under the quasiharmonic approximation (QHA), the temperature and pressure dependencies of the bulk modulus, the Gibbs free energy, the thermal expansion coefficient, as well as the heat capacity at constant pressure are investigated systematically in the ranges of 0–1000 K and 0–30 GPa.