Observations of Intergranular, Crack Deflection Toughening Mechanisms in Silicon Carbide

The fracture toughness of three silicon carbide-based materials were examined in the light of operative toughening mechanisms. Crack deflection along grain boundaries in a hot-pressed SiC-Al₂O₃ and a hot-pressed SiC-ZrO₂ provided notable toughness increases compared with a sintered alpha -SiC, which fractures transgranularly. The existence of a crack deflection mechanism was confirmed using scanning electron microscopy.