First principles calculations of formation energies and elastic constants of inclusions α-Al2O3, MgO and AlN in aluminum alloy

Abstract

In this paper, the formation energies and elastic constants of [Formula: see text]-Al2O3, MgO and AlN in both rock salt (cubic) and wurtzite (hexagonal) structures were investigated by first principles calculations. The results show that the formation energy being −17.8, −6.3, −3.06 and −3.46 eV/formula unit for [Formula: see text]-Al2O3, MgO, AlN (rock salt) and AlN (wurtzite). It suggests that in the ground state, [Formula: see text]-Al2O3 is relatively more stable than MgO and AlN. The elastic properties for a polycrystalline in the ground state were calculated with the obtained elastic constants, the elastic properties reveal the rock salt structure AlN is the hardest particles among all the inclusions, and all of these inclusions are classified as brittle materials, which is detrimental to the ductile nature of aluminum matrix. The calculated anisotropy index shows that the AlN (wurtzite) and [Formula: see text]-Al2O3 have a lower degree of anisotropy compared with MgO and AlN (rock salt). The calculated results are in good agreement with the values of experimental and other works.