Study on the precipitation mechanisms of TiC particles in steel matrix composites fabricated by eutectic solidification

Abstract

The precipitation mechanisms of TiC eutectic particles in steel matrix composites prepared by eutectic solidification are studied through thermodynamic calculations and experimental analyses. The results indicate that the eutectic TiC particles begin to precipitate when the concentrations of Ti and C in the residual molten steel reach a eutectic point during the solidification process. The mass fractions of Ti and C in SMCs play significant roles in the precipitation time, particle characteristics and precipitation mechanism characteristics of TiC eutectic particles. When the mass fractions of Ti and C in SMC are low, TiC particles precipitate in the form of divorced eutectic solidification, showing strip, block and irregular shapes that are mainly distributed on the grain boundaries. When the mass fractions of Ti and C are high, TiC particles precipitate in the form of eutectic solidification, showing flake and dendritic shapes that are distributed on the grain boundaries and also in the grains. There are orientation relationships between the eutectic particles and the matrix.