Elastic properties of ternary (Alx,Mg1−x)Sc random alloys from first principles methods

Alloys in the (Alx,Mg1−x)Sc system were studied computationally in order to investigate the compositional dependence of the elastic properties. The CsCl-type crystal structure was considered, and the Special Quasirandom Structures method was used to generate random models with minimal periodicity error. These models were studied using density functional perturbation theory implemented with planewaves and pseudopotentials to compute the elastic tensors for different compositions. It was found that addition of Mg to the alloy up to 20 at% preserves the Young's modulus, while further addition of Mg led to lower densities but also decrease of elastic moduli and increased brittleness.