First-principles Investigations On Structural, Mechanical And Electronical Property Of WC And ReC

Transition metal carbides have been widely used in industrial fields such as cuttingtools and wear-resistant coatings owing to their superior hardness, high melting point,good wear resistance and excellent thermal conductivity. Future studies are ofconsiderable scientific and technological significance of transition metal carbides. Theproperties of WC and ReC with different structures under high pressure aresystematically investigated by the first-principles calculations in the frame of densityfunction theory.Investigations indicate that the most stable WC is in WC-type, then MoC-typefinally NaCl-type, and WC-type ReC possesses higher stability than NiAs-type. It can befound that WC and ReC in different structures are all ultra-incompressible materials.Through investigating the pressure dependence of elastic constants we found that WCand ReC are mechanical stable in the pressure range from0to100GPa. We alsodemonstrated that they are all elastic anisotropy, and the compressibility along the c-axisis smaller than along the a-axis. The high elastic modulus and shear modulus reveal thatWC and ReC are potential superhard materials. With pressure increasing, the elasticconstants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and B/G in allthe considered structures all increase monotonically. The analysis of band structure anddensity of states imply that WC and ReC are metallic, and the pressures can improve thestructural stability. Based on the quasi-harmonic Deby model, the reduced latticeconstants, isothermal bulk modulus, heat capacity at constant pressure, Deby temperature,volume thermal expansion coefficient and Grüneisen parameter of ReC at varioustemperatures and pressures were also firstly calculated.