Analysis of fracture toughness and TiC/Al₂O₃ composites

Al₂O₃/TiC composites having various fraction ratio between Al₂O₃ and TiC phases are prepared through the hot-press process. Static and dynamic fracture toughness values are measured experimentally. Crack deflection angle and areal fraction of each fracture path (intergranular and transgranular fractures both through the Al₂O₃ and TiC phases and Al₂O₃/TiC interface) are measured on lateral surface of specimens and fracture surfaces, respectively. Local fracture toughness in each fracture path is analyzed using the above data. Measured fracture toughness increases with the increase in the mass percent TiC phase. Local fracture toughness is higher for the passes through the TiC phase than those through the Al₂O₃ phase, whether it is transgranular or intergranular. The weakest path is the Al₂O₃/TiC interface in all of the samples. Microstructural configuration for improved fracture toughness in Al₂O₃/TiC composites is discussed in light of local fracture toughness at both grain interior and boundaries.