Structural evolution of the Ti-Si-C system during mechanical alloying

Investigation on the structural evolution for the Ti-Si-C system during mechanical alloying (MA) using a planetary ball mill was systematically performed under identical milling conditions. Experimental results on different powder mixtures were examined and compared. Two kinds of mechanically induced chemical reactions were observed in the Ti-Si-C system, which depends on the composition of the ball-milled mixtures. Gradual reaction was observed in both the Ti50C50 and Si50C50 mixtures, and TiC and SiC as the resultants were obtained, respectively. The reaction of Ti50Si50 mixture during MA was also a gradual reaction, but the resultants are crystalline Ti5Si3 and an amorphous phase. The TiC-SiC composites, however, were synthesized by mechanically alloying the Ti25Si25C50 powder mixture through a mechanically induced self-sustaining reaction (MSR) under the same milling conditions as those of Ti50C50, Si50C50 and Ti50Si50 mixtures. So the MSR process might be applied to synthesize TiC-SiC composites. The structural evolution processes and thermodynamics of the reactions are discussed.