Elastic Moduli of (Ni,Cu)3Sn4 Ternary Alloys from First-Principles Calculations

Based on first-principles calculations, the effect of Cu solubility on the elastic moduli of Ni₃Sn₄-based intermetallic compound (IMC) is investigated. It is found that the stiffness tensor of a (Ni,Cu)₃Sn₄ single crystal is anisotropic, and the presence of Cu in the crystal compound reduces the moduli of (Ni,Cu)₃Sn₄ due to reduced hybridization between Ni and Sn states. Furthermore, our results show that higher Cu concentration in the (Ni,Cu)₃Sn₄-based IMCs leads to thermodynamically less stable compounds. Based on the single-crystal results, the elastic properties of polycrystalline (Ni,Cu)₃Sn₄ are also obtained.