Preparation of Ti-TiB-TiC & Ti-TiB composites by in-situ reaction hot pressing

Abstract

Discontinuously reinforced Titanium matrix composites, with TiB and TiC reinforcements, have been produced by the reaction hot pressing process. Powder metallurgy approach has been adopted with two different starting powder mixtures, namely Ti+TiB2 and Ti+B4C, the former leading to a composite with only TiB reinforcement, while the latter resulted in a combination of TiB+TiC reinforcement. The initial composition was adjusted in such a way as to have a reinforcement content of 70% by volume, the rest being matrix titanium. The X-ray diffraction analysis confirmed the completion of reaction and the scanning electron microscope studies revealed the morphology of the reinforcement. The effect of morphology and reinforcement type on mechanical properties was evaluated with hardness measurement and 3-point bend tests. It is concluded that the composite with the TiB+TiC reinforcement has a better strength and toughness, due to the presence of needle shaped TiB, while the composite with only TiB reinforcement in the form of TiB particulate has inferior strength and fracture resistance.