First‐principles study on the structural, phonon, and thermodynamic properties of the ternary carbides in Ti–Al–C system

The structural, phonon, and thermodynamic properties of the ternary carbides Ti 2 AlC, Ti 3 AlC, and Ti 3 AlC 2 in the Ti–Al–C system are investigated by using first‐principles calculations in this paper. Phonon dispersion curves and partial density of states have been investigated and revealed the different Ti–C bond characteristics between Ti 3 AlC and the two other compounds. The Gibbs energy, entropy, heat capacity, and thermal expansion coefficient of the three compounds are predicted by means of the quasi‐harmonic approximation. Furthermore, the thermal electronic contribution has been included in the thermodynamic properties. The obtained results of this study are in good agreement with the available experimental data.