Effect of Ball Milling on Reaction Mechanism between Ti and B4C and Subsequent Densification

The effect of ball milling pretreatment of the starting Ti and B4C powder blends on the synthesis of dense TiB2/TiC composite was investigated. X-ray diffraction analysis showed that the TiC phase was not produced until the milling time was up to 18h and only a minimal amount of TiB2 was generated, even after 48h of milling. It is clear that no complete conversion of the starting reactants to the desired products characterized as TiB2/TiC powder mixture take place within the investigated conditions. The decreased particle sizes of the reactants and high concentration of defects induced from ball milling, allow the completely chemical reaction of reactants into the desired composition (2TiB2/TiC), corresponding to the rapid and significant sample shrinkage occurring before 500°C. The target products obtained starting from mechanical activation reactants also showed relatively uniform microstructures and densities greater than 98% of the theoretical value.