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

• Numerically analyze the rim formation of Ti(C,N)-based cermets by Ostwald ripening
• Develop a model analyzing the rim formation of the cermets by grain growth
• Develop a method identifying which one of the above-mentioned mechanisms is dominant during the sintering
• Study the dominant rim formation mechanism in Ti(C,N)-Mo2C-Ni cermets during the sintering

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.