Effect of TiC particles on the liquid–liquid decomposition of Al–Pb alloys

Abstract

The microstructure formation during a liquid–liquid phase transformation of immiscible alloys remains an unsolved scientific problem. In this work, casting experiments were carried out to investigate the effect of TiC particles on the liquid–liquid phase transformation of Al–Pb alloys. SEM and EDS investigations reveal that TiC particles can be used as inoculants for the nucleation of the Pb-rich droplets during the liquid–liquid decomposition of Al–Pb alloys and promote the formation of Al–Pb alloy with a dispersed microstructure. A model was developed to describe the kinetic behavior of TiC particles and the precipitation of the Pb rich droplets in the melt. The dissolution, coarsening and precipitation of TiC particles during the whole process from the very beginning of the addition of TiC into the melt till the liquid–liquid phase transformation of the Al–Pb alloy were calculated. It is demonstrated that if the number density of the TiC particles in the melt cooled to the binodal line temperature of Al–Pb alloys is high enough, the addition of TiC causes a refinement of the Pb-rich droplets/particles.