First-principles calculations of structural stability and mechanical properties of tungsten carbide under high pressure

•Theoretical study of structural stability of WC under high pressure.•Mechanical properties of WC are investigated by first-principle calculations.•Elastic anisotropy of WC in the three structures upto 100 GPa is discussed in detail.

The structural stability and mechanical properties of WC in WC-, MoC- and NaCl-type structures under high pressure are investigated systematically by first-principles calculations. The calculated equilibrium lattice constants at zero pressure agree well with available experimental and theoretical results. The formation enthalpy indicates that the most stable WC is in WC-type, then MoC-type finally NaCl-type. By the elastic stability criteria, it is predicted that the three structures are all mechanically stable. The elastic constants Cij, bulk modulus B, shear modulus G, Young׳s modulus E and Poisson׳s ratio ν of the three structures are studied in the pressure range from 0 to 100 GPa. Furthermore, by analyzing the B/G ratio, the brittle/ductile behavior under high pressure is assessed. Moreover, the elastic anisotropy of the three structures up to 100 GPa is also discussed in detail.