Experimental investigations and thermodynamic calculations of the structural and phase composition in the Ti–Si–C system

Abstract

Thermodynamic calculations of the structural-phase equilibrium in the Ti–Si–C system at 1100–1400°C are performed using the CALPHAD method. Calculated phase diagrams of this system are presented. It is established that 100% of the Ti3SiC2 phase is formed with the stoichiometric component ratio. With the deviation of the carbon or silicon content, titanium carbide, titanium disilicide, or silicon carbide appear in the system. The temperature almost does not affect the phase composition in the studied temperature range. The calculated data are compared with the experimental determination of the phase composition of the samples of the mentioned system after the spark-plasma sintering of the mechanically activated powder composition. In practice, the process temperature and duration of high-temperature holding substantially affect the phase composition of the final product, which is associated with the limited rate of solid-phase reactions during the synthesis of compounds. The samples have a grain size of 1–5 μm and hardness of 4–15 GPa, depending the phase composition.