Overview of geometric effects on coarsening of mushy zones

An overview is presented of the thermodynamic, kinetic, statistical, and geometric factors that govern phase coarsening in dendritic mushy zones. The coarsening behavior of such systems is best quantified through the kinetics of the decay rate of the specific surface area, S-v. The geometry of the complex solid-melt interfaces comprising a mushy zone is described statistically as an areal distribution of local curvature parameters. These parameters capture both the intensive and extensive thermodynamic characteristics of the mushy zone. The effects of local interface shape, negative mean, and Gaussian curvatures and the appearance of inactive lengthscales on the coarsening kinetics of dendritic structures are discussed. The combined contribution of all these geometrical effects yields global coarsening rates for ramified mushy zones that are comparable to those predicted from theory for a collection of spherical particles having the identical volume fraction of solid.