TiB2-based Multiphase Ceramics for Cutting Materials Synthesized by Reactive Casting Based on Ti-B4C System

TiB2-based multiphase ceramics for cutting materials were prepared by reactive casting processing in high-gravity field using Ti and B4C powders as raw materials. The phase composition, microstructures and hardness of the final ceramics were studied. The results show that the final ceramics are composed of TiB2 and TiC with unique microstructures where TiB2 crystals with the rectangular shape are regularly distributed between the irregular TiC solids. The ceramics are presented with typical solidified morphology where TiB2 crystals are well-bonded with TiC solids. It is proposed that the combined action between high-gravity field and ball-milling processing accelerates the reaction between Ti and B4C powders, and promotes the formation of a large number Ti-B-C melt and a few undissolved TiB2 and TiC1-x crystal nucleus. It is considered TiC solids grow much more rapidly than TiB2 due to the faster diffusion of C relative to B in Ti-B-C melt. Due to the rapid growth of TiC solids, growth of rectangular TiB2 crystals is suppressed and fine-grained microstructures are formed with the characteristic dimension of 2 mu m approximately.