Evolution of Macrosegregation During Directional Solidification of Binary Alloys

Various causes of macrosegregation during solidification of alloys, and important findings from investigations by the present authors on role of material parameters, permeability of the mushy region and cooling rate have been reviewed, and important results presented. The investigations consisted of mathematical model development and controlled experiments. The role of material parameters on macrosegregation was analyzed through comparative study of three alloy systems, viz., ammonium chloride-water, iron-carbon and lead-tin. The effect of cooling rate on thermosolutal convection and macrosegregation in iron-carbon system was highlighted through a series of numerical simulations. Some highlights of controlled experiments on vertical solidification of lead-tin alloys, and its analysis with the help of the mathematical model are presented.