Microstructure and mechanical properties of self-Reinforced alpha–Silicon carbide

Abstract

Fine (0.46 μm) α-SiC powders with or without large (2 μm) α-SiC particles (seeds) added were pressureless-sintered at 1900°C for 1, 4, and 8 h with addition of yttrium aluminum garnet (YAG). The introduction of larger seeds into fine α-SiC accelerated the grain growth of some α-SiC grains and resulted in self-reinforced microstructure consisted of large elongated grains and small equiaxed grains. In contrast, the material without seeds had a relatively equiaxed grain structure. Development of self-reinforced microstructure results in significant improvements in toughness. However, the improved toughness is offset by a significant reduction in strength. The fracture toughness of the 8-h sintered materials without or with seeds was 4.6 and 6.2 MPa m 1/2, respectively.