Introduction

The understanding of metal alloy solidification processes is essential to all types of casting operations.  While pure substances solidify with a sharp freezing front that coincides with the isotherm corresponding to the phase-change temperature Tf, the situation is much more complex when dealing with alloys, or multi-constituent systems.  With multi-constituent systems the phase change takes place over a range of temperature where solid and liquid may coexist in equilibrium.  Although an alloy can solidify with planar solid-liquid interfaces if the ratio of the freezing interface heat flux and freezing interface growth velocity is sufficiently large, most alloys solidify with the formation of a two phase region known as mushy zone, which is composed of solid dendrites and inter-dendritic liquid. The shape, extend and advancement of the mushy zone depend on may factors including specific solidification conditions, initial composition of the liquid melt, etc

A new project on modelling solidification was started in Jan 2004 with a seed fund from the LNCSR for the developement and implementation of a two phase model for the simulation of casting operations.

The characteristics of the model are

- ability to predict macrosegregation

- use of a microsegregation model

- binary alloys solidification