Cooperative grain boundary and phase boundary migration for the grain growth in NbC-based cemented carbides

A simple model is proposed to analyze the effect of grain boundaries on grain growth in a system of solid particles in equilibrium with a liquid. In the presence of a significant amount of grain boundaries, a cooperative migration of grain boundaries and phase boundaries is necessary for grain growth in stationary conditions. Existing models are combined to take into account grain boundary migration beside dissolution-precipitation in the liquid by the classical Ostwald ripening mechanism. The model is applied to the analysis of grain growth during liquid phase sintering of cemented carbides, characterized by a high volume fraction of solid with highly imbricated particles. An experimental study shows that phase boundary and grain boundary migration are competitive in the NbCNi system and transition from a control by grain boundaries to a control by diffusion in the liquid is observed as grain growth proceeds.