INFLUENCE OF CONVECTION ON ROD SPACING OF EUTECTICS

This paper describes a three-dimensional numerical model to study the influence of convection on the rod-like microstructure of an eutectic system. This model is based on a central finite difference approach. By applying it, the average concentration near the solid/liquid interface of a growing rod-like eutectic was determined for eutectic compositions Ce of 0.03, 0.05 and 0.10. Following Jackson and Hunt, the average interfacial composition was converted to a change of undercooling at the interface and, finally, to spacing between the rods. The change in rod spacing with increasing intensity of convection was calculated assuming the eutectic grows at minimum interfacial undercooling. It was confirmed that an increase in convection should coarsen the microstructure, i.e. the rod spacing increases with increasing intensity of stirring. The direction of the convection relative to the rod array is a very important parameter in such an analysis. © 1990.