No abstract

An extended non-steady-state model for the interaction between a solid particle and an advancing solid/liquid interface based on the dynamic model of Catalina et al. (Metall Mater Trans A 31:2559â2568, 2000) is used to calculate the critical velocities for the pushing/engulfment transition in Si-SiC system under microgravity and under normal gravity conditions. The aim of this study was to explain the abnormal behavior of the critical velocity in experiments. The simulations were carried out for two cases of the drag force formulation. The effects of the non-spherical form of the particles as well as the cluster formation were also taken into account. It is found that in the presence of the gravity force, the particles will be engulfed when the particle size exceeds a certain limit which does not depend on the choice of the drag force formulation