2007 Volume 48 Issue 9 Pages 2272-2279
A theoretical model is developed to predict the characteristics of a needle (cellular or dendrite) interface during the controlled and arrayed solidification of binary alloys. Both heat and mass transport fields near a growing needle front have been considered. The effect of solute, diffused from nearby dendrites, on dimensions of needle is also taken into account. Minimum undercooling criterion of tip of interface has been developed to select a solution to determine the dimensions, satisfying the local equilibrium conditions at the interface. Solutions are classified into two categories; one is responsible to the cellular growth and the other to the dendrite growth. Good correlations are obtained between theory and experiments.
