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

Abstract

The structural, elastic and electronic properties of Al2La, AlLa3 and Al3La 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 Al2La, AlLa3 and Al3La all have a higher structural stability, and the alloying ability of Al2La and Al3La is stronger than that of AlLa3. The single-crystal elastic constants (Cij) 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 Al2La, AlLa3 and Al3La phases were discussed in detail. The results showed that Al2La and Al3La which are anisotropic materials are absolutely brittle, while the isotropic AlLa3 is slightly ductile. Finally, the electronic density of states (DOS) was also calculated to reveal the underlying mechanism of structural stability.