Phase relationships in the Ti–Si–C system at high pressures

The compatibility of phases in the Ti–Si–C system was studied for pressures from 10 to 20 kbars (1 to 2 GPa) and temperatures from 1200 °C to 1500 °C via an interfacial reaction between titanium and silicon carbide. The interface was characterized by backscattered electron imaging and electron probe microanalysis. Ti₃Si was stabilized at high pressures exhibiting an appreciable solubility for carbon (up to 9 at. %). At higher temperatures and lower pressures, it decomposed to Ti₅Si₃, Ti(Si, C), and TiC_x according to the relation Ti₃Si (C_z) = (0.70588)TiC_x + (0.32437)Ti₅Si₃ + (0.67227)Ti (Si, C), where the mathematical coefficients were calculated using z = 0.4 and x = 0.5. No detectable quantities of carbon dissolved in Ti₅Si₃ under these conditions. A clapeyron slope of 0.08 (±0.01) kbar/K was measured for this reaction. The microstructure of the reaction zone and other general thermodynamic and kinetic characteristics are discussed for different experimental conditions.