Work of Adhesion Analysis for Metal-Substituted W₄C₄ Carbides in a Cobalt Matrix

The density of WC, which is greater than that of metals, can be reduced by partially substituting heavy W with metals, e.g., Mo and Cr, while retaining the desired strength. This makes them effective as reinforcements for hard-facing overlays and tool alloys, as they can be homogeneously dispersed in the metal matrix. Since it is unclear if the modified WC has good interfacial bonding with metals such as cobalt, one of the typical metal matrixes for hardfacing overlays, the interfacial bonding between cobalt and WC doped with Mo and Cr, respectively, was investigated via first principle calculations. The selected interfaces having the lowest interfacial mismatches with both HCP and FCC cobalt are (1120)_Carbide//(001)_Co, (1010)_Carbide//(100)_Co, (1010)_Carbide//(110)_Co, and (0001)_Carbide//(110)_Co. The characteristics of created interfacial connections were analyzed using methods such as the electron localization function, electronic density of states, bond order, and net charge. It is demonstrated that WC carbides partially substituted with Mo and Cr (called (W_4-, M)C_4, M = Mo or Cr) are adherent to Co as strong as or even better than that of mono-WC. The metal-substituted or doped W₄C₄ carbides are promising candidates as reinforcements for hardfacing overlays, cutting tools, and bearings without interfacial bonding concerns.