Ostwald ripening and grain growth in Ti(C,N)-based cermets during liquid phase sintering

Abstract

After liquid phase sintering, core-rim microstructure occurs in the grains of Ti(C,N)-based cermets. The mechanisms of the microstructural evolution during different sintering stages were investigated here. Our theoretical analyses show that the rim thickness of a grain is relatively independent of its initial radius when rim formation is dominated by Ostwald ripening during dissolution-reprecipitation stage, whereas it increases linearly with its initial radius when grain growth during subsequent cooling stage is the dominant mechanism. A geometric analysis via cross-sectioning technique is developed to identify dominant rim formation mechanism. Experiments with Ti(C,N)-based cermets show that rim formation is dominated by grain growth at low sintering temperatures and by Ostwald ripening at sufficiently high sintering temperatures.