Mechanical properties and chemical bonding characteristics of WC and W2C compounds

The mechanical properties and chemical bonding features of W–C binary compounds (h-WC, o-W2C, h-W2C and t-W2C) were studied by density functional theory (DFT). It is shown that they are thermodynamically stable identified by the cohesive energy and formation enthalpy of W–C binary compounds. The elastic constants were calculated using the stress–strain method. The Voigt–Reuss–Hill approximation was used to evaluate the moduli. The surface constructions of bulk and Young's moduli were applied to illustrate the mechanical anisotropy. The population analysis of W–C binary compounds was used to discuss the chemical bonding, which indicate the combinations of covalent and metallic bonds in these compounds. Moreover, the anisotropic properties of sound velocities for W–C binary compounds were explored.