Abstract
The growth of mushy zone during solidification of supercooled alloy melt was studied to develop the structure control in material processing. Using the experimental evidence in the previous paper of this work, a theoretical model for primary arm spacing selection in centripetal solidification was presented. The model reflected the ununiformity of crystal arrays at the leading front in the mushy zone and the history dependence of crystal growth. Based on this model, a numerical simulation was carried out for changes of minimum, maximum, average primary arm spacing during the two-dimensional solidification of supercooled Pb-10wt%Sn alloy melt. The validity of this model was made clear by comparing with experimental results. The average primary arm spacing increased stepwisely with distance from the wall while oscillating up and down. Finally, it was clarified that the cycle of change was closely related with temperature gradient of supercooling.
