Equiaxed dendritic solidification in supercooled melts

The growth of equiaxed dendrites from a pure supercooled melt is examined. We propose modifications to the classical Ivantsov theory that allow for co nsideration of multiple interacting dendrites. The modified theory reveals the existence of a steady-state dendritic solidification mode in a frame of reference moving with the dendrite tip. This regime should be valid from t he onset of nucleation to the commencement of time-dependent coarsening whe n the mass of the solid becomes comparable to the liquid mass in the solidi fication chamber. This regime is characterized by a reduced (relative to th e single dendrite case) heat flux leading to slower solidification rates, b ut with the same level of supercooling. We study the effects of the relativ e proximity and number of interacting dendrites through a numerical example of solidification of succinonitrile, a common material used in many experi ments. The data show that the model predicts a new steady growth regime tha t is different than the steady growth law of a single dendrite as described by Ivantsov theory. (C) 1999 Published by Elsevier Science B.V. All rights reserved.