Co-phase penetration ofWC(101¯0)/WC(101¯0)grain boundaries from first principles

We examine different interface energy relationships at the $\mathrm{WC}(101\ifmmode\bar\else\textasciimacron\fi{}0)$ surface in the WC-Co cemented carbide using density-functional theory. To assess the stability of WC/WC grain boundaries, $90\ifmmode^\circ\else\textdegree\fi{}$-twist grain boundaries and a $27\ifmmode^\circ\else\textdegree\fi{}$-twist grain boundary are considered. In addition, we investigate the adhesion properties at the $\mathrm{Co}(001)/\mathrm{WC}(101\ifmmode\bar\else\textasciimacron\fi{}0)$ interface by analyzing twelve different interfacial structures, including both W and C terminations of the carbide. The results indicate that the adhesion properties of Co on $\mathrm{WC}(101\ifmmode\bar\else\textasciimacron\fi{}0)$ can be explained either by a considerable adjustment of the interfacial Co atoms to their interfacial equilibrium positions, or by an interfacial structure where the WC surface has a mixed composition of C and W atoms. Finally, the WC/WC grain boundary and Co/WC interface energy relationships are discussed in the context of liquid-phase sintering.