Critical velocities for particle pushing by moving solidification fronts

Abstract

A theory is developed for evaluation of critical velocities for pushing of particles by solidification fronts. A numerical simulation is done in which the critical velocity is evaluated as a function of particle size, thermal conductivity, temperature gradient as the solidification front, the Hamaker constant of interaction between the particle and the front, solid-liquid interfacial energy and melt viscosity. The shape of the solidification front under steady state pushing conditions as well as the changes in shape that take place during the non-steady state engulfment process can be determined using this theory. The critical velocity is shown to be closely linked to the shape of the solidification front and hence to all the parameters that affect the shape of the front.