First-principles studies of defects, mechanical properties and electronic structure of Cr-based Laves phases

Abstract First-principles calculations have been performed to investigate the defects, mechanical properties and electronic structure of MCr 2 (M = Nb, Ti and Zr) Laves phases. The results show that the ternary additive of V preferentially substitutes the Cr site and Zr the Nb site in NbCr 2 . W has a weak site preference on the Cr site in NbCr 2 . The ternary site substitutions are related to the electronic structure of NbCr 2 . Further calculations of the densities of states and charge density distribution of TiCr 2 show that a strong covalent bonding between the small atoms (Cr) along the Kagome net forms a tetrahedral electronic network, which is a common feature for the electronic structure in Laves phases. Mechanical properties, such as elastic constants, elastic moduli and stacking fault energies of ZrCr 2 , were calculated additionally. The intrinsic and extrinsic stacking fault energies of ZrCr 2 are found to be 112 mJ m −2 and 98 mJ m −2 , respectively.