Preparation of TiC-Ti3SiC2 composites by mechanical alloying and hot-pressing

TiC-Ti3SiC2 composites having the microstructure of fine Ti3SiC2 grains dispersed in TiC matrix were synthesized by two processes, that is. mechanical alloying of a powder blend of Ti, Si and C followed by hot-pressing (MA-HP process) and hot-pressing of a powder blend of Ti, Si and TiC (MIX-HP process). The microstructure, damage tolerance and 4-point flexural strength of the composites were investigated. It was found that more uniform dispersion of Ti3SiC2 grains in TiC matrix was achieved by MA-HP process than by MIX-HP process, while the flexural strength of the composites synthesized by MA-HP process was lower than that by MIX-HP process. which may be attributed to micropores formed in the composites synthesized by MA-HP process. Preferential orientation of Ti3SiC2(001) and TiC(111) occurred in the composites synthesized by MA-HP process. We proposed two mechanisms of the preferential orientation. We also found that the dispersion of Ti3SiC2 in TiC matrix is effective in improving the damage tolerance of the brittle TiC. evidenced by the fact that no cracks emanated front the corners of Vickers indentations at a load of 9.8 N.