First-Principle Studies on the Mechanical and Electronic Properties of Al_xNi_yZr_z (x = 1~3, y = 1~2, z = 1~6) Alloy under Pressure

The elastic and electronic properties of Al_xNi_yZr_z (AlNiZr, Al₂NiZr₆, AlNi₂Zr, and Al₅Ni₂Zr) under pressure from 0 to 50 GPa have been investigated by using the density function theory (DFT) within the generalized gradient approximation (GGA). The elastic constants C_ij (GPa), Shear modulus G (GPa), Bulk modulus B (GPa), Poisson's ratio σ, Young's modulus E (GPa), and the ratio of G/B have been studied under a pressure scale to 50 GPa. The relationship between Young's modulus of Al_xNi_yZr_z is Al₅Ni₂Zr > AlNiZr > Al₂NiZr₆ > AlNi₂Zr, which indicates that the relationship between the stiffness of Al_xNi_yZr_z is Al₅Ni₂Zr > AlNiZr > Al₂NiZr₆ > AlNi₂Zr. The conditions are met at 30 and 50 GPa, respectively. What is more, the G/B ratios for AlNiZr, AlNi₂Zr, Al₂NiZr₆, and Al₅Ni₂Zr classify these materials as brittle under zero pressure, while with the increasing of the pressure the G/B ratios of AlNiZr, AlNi₂Zr, Al₂NiZr₆, and Al₅Ni₂Zr all become lower, which indicates that the pressure could enhance the brittle properties of these materials. Poisson's ratio studies show that AlNiZr, AlNi₂Zr, and Al₂NiZr₆ are all a central force, while Al₅Ni₂Zr is a non-central force pressure scale to 50 GPa. The energy band structure indicates that they are all metal. The relationship between the electrical conductivity of Al_xNi_yZr_z is Al₂NiZr₆ > Al₅Ni₂Zr > AlNi₂Zr > AlNiZr. What is more, compared with Al₅Ni₂Zr, AlNi₂Zr has a smaller electron effective mass and larger atom delocalization. By exploring the elastic and electronic properties, they are all used as a superconducting material. However, Al₅Ni₂Zr is the best of them when used as a superconducting material.