Generalized stacking fault energies of intermetallic compounds AlSc and MgSc at different pressures using first principles

Intermetallic compounds with B2 structure are used in aviation and aerospace, but lower ductilities are required for these materials. Here, to better understand the properties of this class of compound, the lattice constants of the intermetallic compounds AlSc and MgSc with B2 structure were calculated via first-principles methods, along with the their phase transition pressures. The generalized stacking energy curves of AlSc and MgSc at different pressures were also calculated, and the generalized stacking energy surface was fitted. The results reveal that, under pressure, < 111>{110} remains the sliding system of B2-type AlSc and MgSc. As the pressure increases, the antiphase boundary energies and unstable stacking fault energies of the two materials in all directions gradually increase. This means that the more energy required for dislocation in the process of sliding, the lower the ductility of the material. Comparing the phase change pressures of the two materials, it can be seen that AlSc has greater compressive resistance than MgSc, but for MgSc, at pressures lower than the phase change pressure, its ductility is greater than that of AlSc.