First-principles investigation of the elastic and electronic properties of the binary intermetallics in the Al-La alloy system

The structural, elastic and electronic properties of Al ₂La, AlLa ₃ and Al ₃La binary intermetallics in the Al-La alloy system were investigated using the first-principles method. The calculated lattice constants were consistent with the experimental values. Formation enthalpy and cohesive energy showed that the studied Al ₂La, AlLa ₃ and Al ₃La all have a higher structural stability, and the alloying ability of Al ₂La and Al ₃La is stronger than that of AlLa ₃. The single-crystal elastic constants (C _ij) as well as polycrystalline elastic parameters (bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio υ and anisotropy value A) were calculated by the Voigt-Reuss-Hill (V-R-H) approximations, and the relationship of these elastic parameters between Al ₂La, AlLa ₃ and Al ₃La phases were discussed in detail. The results showed that Al ₂La and Al ₃La which are anisotropic materials are absolutely brittle, while the isotropic AlLa ₃ is slightly ductile. Finally, the electronic density of states (DOS) was also calculated to reveal the underlying mechanism of structural stability.