First-Principles Study of Substitution of Cu and Au for Ni in Ni3Sn2

The effects of substitution of Cu and Au for Ni on the mechanical, thermodynamic and electronic properties of two different Ni3Sn2 structures are investigated by first-principles calculations. Cu atom at Ni2 site and Au atom at Ni1 site of the eta phase lead to the thermodynamic stable structure. For the lambda phase, Au atom can only replace the Ni1 site. Substitution causes the decrease of the polycrystalline elastic modulus and the Debye temperature. The degree of anisotropy along Z axis decreases dramatically for eta phase, but it increases along Y axis for lambda phase after substitution. The Ni3Sn2-based intermetallics are all ductile; the eta phase is more ductile than the lambda phase. The electronic density of states manifest an energy gap appearing in eta phase and the effective mass of the eta phase is lower than lambda phase.