Processing of composites in the Ti-Si-C system

New composites utilizing Ti₃SiC₂ as the matrix phase have been synthesized. The thermal and kinetic aspects of the phase formation in the Ti-Si-C system were examined. Standard dry powder processing techniques, pressureless sintering and hot pressing (both under inert atmosphere) were employed to process the sample materials. The phase identification was performed by X-ray powder diffraction (XRPD) analysis. The ratio of the volume fractions of the reinforcement phases SiC and/or TiC _x to the matrix phase Ti₃SiC₂ have been measured and tailored over a wide range by means of controlling the stoichiometry of the starting elemental powders and varying the heat treatment. It was found that the Si tends to evaporate at elevated temperatures during sintering. The loss of Si is the likely reason why it is difficult to form the single phase Ti₃SiC₂. Incorporating this observation into the composite formation, a method to form in-situ composites is proposed. The volume fraction of the constituent phase in the composite can be controlled by varying the processing parameters.