Solidification pathways and phase equilibria in the Mo-Ti-C ternary system

Abstract

The liquidus surface projection and isothermal section at 1,800°C in the Mo-Ti-C ternary system are examined using arc-melted alloys. A ternary transition peritectic reaction (L + Mo2C → Mo + TiC) takes place during solidification, which is apparently different from the ternary eutectic reaction (L → Mo + TiC + Mo2C) observed in a previous report. Since the composition of the eutectic reaction (L → Mo + TiC) shifts toward the Mo-Ti binary line with increasing Ti concentration, the volume fraction of the Mo phase and the interlamellar spacing of the Mo and TiC phases increase in the eutectic microstructure. At 1,800°C, the TiC phase in equilibrium with the Mo phase can contain more than 28 at% Mo and a Mo/TiC/Mo2C three-phase region exists at around Mo-15Ti-10C.