Temperature dependence of stacking-fault and anti-phase boundary energies in AlSc from ab initio calculations

Abstract

Temperature dependence of intrinsic stacking-fault energies (SFE) and anti-phase boundary energies (APBE) of AlSc is investigated in first-principles calculations using the axial Ising model and supercell approach. The temperature effect has been taken into consideration by including the one-electron thermal excitations in the electronic structure calculations, and vibrational free energy in the harmonic approximation as well as by using temperature dependent lattice constant. The latter has been determined within the Debye–Grüneisen model, which reproduces well the experimental data. The APBE and SFE are found to be reduced by about 10% in the temperature interval from 0 to 1000 K. It is shown that the inclusion of the free energy of lattice vibrations in the harmonic approximation increases the SFE further by about 4%. We also find a substantial contribution from local lattice relaxations in the case of APBE for the (1 1 1) plane and SFE leading to their reduction by about 30%.