First-principles study of structural and electronic properties of C14-type Laves phase Al2Zr and Al2Hf

Structural, mechanical and electronic properties of Laves phases Al2Zr and Al2Hf with C14-type structure were investigated by performing the first-principle calculations. The calculated equilibrium structural parameters agree closely with available experimental values. Mechanical parameters, such as bulk modulus B, shear modulus G, Young's modulus E and the Poisson's ratio m are determined within the framework of the Voigt-Reuss-Hill approximation. We show that both Al2Zr and Al2Hf are mechanically stable and brittle with the estimation from the Poisson's ratio and the B/G relationship. The mechanical anisotropies of the two phases are discussed in detail using several different anisotropic indexes and factors, showing that the anisotropy degree of Al2Hf is slightly larger than that of Al2Zr. In addition, the Debye temperature and anisotropic sound velocity of the two phases are predicted. Finally, the electronic structures are determined to reveal the bonding characteristics of both phases. These results are helpful to deepen the understanding of the physical and chemical nature of C14-type Al2Zr and Al2Hf. (C) 2013 Elsevier B. V. All rights reserved.