TiC-TiB2 composites : A review of phase relationships, processing and properties

Ceramic-matrix composites (CMCs) based on TiC-TiB2 have attracted enormous interest during recent years because, in comparison to singlephase ceramics, they exhibit superior properties including high hardness, good wear resistance and high fracture toughness. This paper begins with a review of the TiC-TiB2 equilibrium system and its possible influence on the processing and properties of the composite. The application of TiC-TiB2 composites has been limited due to the fact that they have been difficult to process. Much of the research effort has therefore focused on the synthesis, processing and fabrication of TiC-TiB2 and is based primarily on self-propagating high-temperature synthesis (SHS) and its derivatives, high-energy milling and sintering. The performance of SHS under the application of pressure has been the subject of particular investigation. These developments are the main subject of this review that also takes into account the resulting effects on the microstructure and the mechanical properties of TiC-TiB2. The influence of the reaction parameters like reactant composition, reactant particle size and green density on the microstructure and properties is also reported.