First-principles simulations of the interface adhesion and wettability: Cu(111)/TiC(111) versus Cu(111)/WC(0001)

The adhesion and wettability of Cu(111)/TiC(111) and Cu(111)/WC(0001) interface system were studied by first-principles simulations comparatively. It is found that the C terminal is more active than metal (Ti, W) terminal in both TiC(111) and WC(111) due to the high surface energy, and thereby the C terminal is more likely to form the interface with Cu. The hybridization between the Cud and Cp orbital leads to a strong Cu-C bonding at the interface, which makes the Wsep of C terminal interface is higher than the metal terminal interface. In addition, the W-C covalent bond weakens the Cu-C electronic interaction at the Cu/WC interface, leading to a lower Wsep of Cu(111)/WC(0001) comparing to the Cu(111)/TiC(111). The wetting angle of metal/carbide can be calculated by the combining of the surface energy and interface energy, and the C-terminated Cu(111)/TiC(111) system has the lowest wetting angle. The DOS results demonstrated that the bonding strength between metal and carbide rely not only on the types of carbide, but also on the electronic structure of metal.