MICROSTRUCTURAL CHARACTERIZATION AND MECHANICAL PROPERTIES OF HOT ISOSTATICALLY PRESSED SiC/Si_3N_4 AND SiC/β-SIALON COMPOSITES

摘要

Two kinds of SiC-based composites, SiC/Si_3N_4 and SiC/β-Sialon, prepared by hot isostatic pressing (HIP) have been studied. The microstructure was characterized by transmission electron microscopy (TEM) and high resolution electron microscopy (HREM), and the relationship between microstructure and mechanical properties was discussed. In the composites of SiC/ Si_3N_4, residual amorphous phase existed both in the grain boundaries and in the triple-grain junction. It corresponds to the higher bending strength, medium indentation fracture toughness and lower Vickers hardness. While in the SiC/β-Sialon composite, no residual amorphous phase was found in the microstructure. The composite with clean grain boundaries corresponds to the medium bending strength, lower indentation fracture toughness and higher Vickers hardness.