First-principles calculations of the stability and hydrogen storage behavior of C14 Laves phase compound TiCrMn

• Mn atoms would optionally substitute on the Cr sites in TiCr2 phase.
• The anisotropy of TiCrMn is small.
• The chemical bonding for TiCrMn is composed of metallic, covalent and ionic nature.
• TiCrMn phase has a better stability of atomic hydrogen atoms.

The structural, elastic properties, electronic structure and hydrogen storage behavior of TiCrMn with a hexagonal C14 structure were investigated by the first-principles calculations within the frame work of DFT. The calculated lattice constants were consistent with the experimental values, and obtained cohesive energy and formation enthalpy showed TiCrMn is of the structural stability. These results also indicated that Mn atoms would optionally substitute on the Cr sites of TiCr2 phase to form the ternary intermetallic TiCrMn. The five independent elastic constants as well as polycrystalline elastic parameters (bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio ν and anisotropy value A) were calculated, and then the ductility and elastic anisotropy of TiCrMn were discussed in details. Furthermore, the electronic DOS and charge density distribution of TiCrMn were also calculated, which revealed the underlying mechanism of structural stability and chemical bonding. Finally, the binding energy of hydrogen in hydride TiCrMn(H3) was investigated, confirming the better hydrogen storage behavior of C14 Laves phase TiCrMn.

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