Deformation and Fracture of TiC/Mo(Nb) In-Situ Composites
TiC having high melting temperature (3340 K) and relatively low density (4.9 Mg • m−3) is considered to be promising as structural material at very high temperatures above 1500 K. Industrial applications of TiC have been limited, however, only to hard materials or cutting tools because of its low fracture toughness at ambient temperature. To improve the fracture toughness is essential to develop TiC as a structural material. Many studies have addressed the improvement of fracture toughness in ceramics by incorporating a second phase1. Among them, some as-synthesized ex-situ (artificial) composites reinforced by a second phase were found to possess fracture toughness of an acceptable value for industrial material. However, the ex-situ composites consisting of non-equilibrated constituents were degraded in fracture toughness as well as high temperature strength during exposure to high temperature owing to the formation of brittle phase(s) at the interface. These results suggest that a second phase which can be equilibrated with a ceramic should be incorporated to improve the mechanical properties of ceramics at ambient and elevated temperatures.
KeywordsFracture Toughness Electron Probe Micro Analyzer High Temperature Strength Ductile Phase Show Scanning Electron Microscope Micrographs
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