COMBUSTION SYNTHESIS OF MOSI2-TIC COMPOSITES

Stability of the binary phases in the quaternary system Mo-Ti-Si-C was examined for the combustion synthesis or Self-propagating High-temperature Synthesis (SHS) of MoSi2-TiC composites. Thermochemical calculations were carried out to obtain the adiabatic temperatures and the amounts of molten phases at the adiabatic temperature for the SHS of these composites. MoSi2-20 wt. % TiC and MoSi2-40 wt. % TiC composites were prepared by thermal explosion and SHS modes of combustion from elemental powders. The phase formation was confirmed by x-ray diffraction, and the morphologies were observed under SEM. No general correlation was obtained between the phase formation or product morphology on the one hand, and the adiabatic temperature or the amount of molten phase formed at the adiabatic temperature, on the other. MoSi2-40 wt. % TiC composites obtained by SHS mode of combustion show a highly homogeneous distribution of the two phases with negligible amounts of ternary phases.