Coarsening in liquid-phase-sintered alpha-SiC

Liquid-phase-sintered (LPS) SiC ceramics represent a new class of microstru cturally toughened structural materials. In order to understand better the microstructural evolution in these ceramics, the coarsening kinetics in LPS alpha-SiC, containing a yttrium aluminum garnet (YAG) based liquid phase, was studied. It was confirmed that the coarsening occurs primarily by solut ion-reprecipitation (Ostwald ripening). Most importantly, the SiC grains we re found to be faceted in nature, and the coarsening rate was found to be i ndependent of the vol.% liquid in the system or the average diffusion path length. Based on these observations it is inferred that interface-reaction controls the solution-reprecipitation coarsening in LPS SiC. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights received.