Morphology of WC grains in WC–Co alloys: Theoretical determination of grain shape

A theoretical approach to predict grain morphology from interface energies computed using density-functional theory is presented and applied to the WC–Co system. The dependences of the WC grain shape on the geometrical misfit at the Co/WC metal–ceramic interface, and on the carbon chemical potential are investigated. The WC grains are predicted to be hexagonal when the interfaces are assumed to be coherent, and change to a truncated triangular shape where the long prism side lengths are five times longer than the short side lengths, when the interfaces are assumed to be incoherent.