STUDY ON HEAT-TREATMENT OF AIN/SiCw COMPOSITES AND EFFECTS ON MICROSTRUCTURE AND PROPERTIES

AlN-SiC whisker composites with YOand SiOadditives were heat-treated at 1300 C in air. The phase crmposition and microstructure were analyzed using XRD, SEM and HREM techniques to study the effect of heat-treatment on the microstructure and properties of the composites. The results reveal that the mechanical properties and high temperature oxidation resistance of the composite of which additives composition approaches the eutectic poi of YO-SiOcan be improved through the heat-treatment. Glass phase in the grain boundary is observed to react with the surface composition of AlN forming fibrous 2H~8 Sialon, resulting a crossing structure produced by fibrous 2H~8 Sialon and SiC whiskers.