The structures, stability, mechanical properties and electronic properties of X (X=Nb, Ge, Ni) doped Al₂Cu: a first-principle study

The structures, stability mechanical properties and electronic properties of X (X=Nb, Ge, Ni) doped Al₂Cu were studied by first-principles. The results show that the stable structures can be formed are Al₆₄Cu₃₂, Al₆₃Cu₃₂Nb, Al₆₄Cu₃₁Nb, Al₆₃Cu₃₂Ge, Al₆₃Cu₃₂Ni, Al₆₄Cu₃₁Ni. Doping X improved the stiffness of the Al₂Cu. Al₆₄Cu₃₁Ni has the largest stiffness and Al₆₄Cu₃₁Nb has the smallest stiffness. However, the ductility of Al₂Cu is reduced after doping with X. Doping X can greatly reduce the anisotropy of the whole system and the {100}, {010} surface. Among them, Al₆₃Cu₃₂Ge has the lowest degree of anisotropy, and Al₆₄Cu₃₁Ni has the highest degree of anisotropy. Doping Nb cause strong orbital hybridization between Al (3s) and Nb (4d), doping Ni causes strong orbital hybridization between Al (3s) and Ni (3d). The bonding strength and stability of Al₂Cu will be significantly changed by these two elements. (paper)