Phase transformation, microstructure and mechanical properties of Si3N4/SiC composite

The influence of SiC fine particle dispersion on phase transformation, micr ostructure and mechanical properties Of Si3N4 ceramics has been investigate d. While the SiC dispersion simply decreased the densification, it caused c omplex effects on the phase transformation behavior; the transformation was enhanced at low temperatures but suppressed at high temperatures. Since th e phase transformation is a nucleation-grain growth process Of beta -Si3N4 SiC particles plausibly enhance formation of a great number Of P-Si3N4 nucl ei due to the high Si3N4 SiC interfacial energy, but inhibit their further phase transformation and grain growth. The mean size and the aspect ratio o f the obtained P-Si3N4 grains decreased as a result of the SiC dispersion, thus bringing about increased flexural strength and decreased fracture toug hness. (C) 2001 Elsevier Science Ltd. All rights reserved.