EN
First-principles calculations were performed to study on alloying stability, electronic structure, and mechanical properties of Al-based intermetallic compounds. The results show that the lattice parameters obtained after full relaxation of crystalline cells are consistent with experimental data. The calculation of cohesive energies indicated that the structure stability of these Al-based intermetallics will become higher with increasing Zr element in crystal. The calculations of formation energies showed that AlCu_2Zr has the strongest alloying ability, followed by AlZr_3 and finally the AlCu_3. Further analysis finds out that single-crystal elastic constants at zero-pressure satisfy the requirement of mechanical stability for cubic crystals. The calculations on the ratio of bulk modulus to shear modulus reveal that AlCu_2Zr can exhibit a good ductility, followed by AlCu_3, whereas AlZr_3 can have a poor ductility; however, for stiffness, these intermetallics show a converse order. The calculations on Poisson's ratio show that AlCu_3 is much more anisotropic than the other two intermetallics. In addition, calculations on densities of states indicates that the valence bonds of these intermetallics are attributed to the valence electrons of Cu 3d states for AlCu_3, Cu 3d and Zr 4d states for AlCu_2Zr, and Al 3s, Zr 5s and 4d states for AlZr_3, respectively; in particular, the electronic structure of the AlZr_3 shows the strongest hybridization, leading to the worst ductility.