Crystal nucleation and growth rates in single-component and binary melts under conditions of growth in a polycrystalline layer and in the case of single crystals

Crystal nucleation and growth rates in single-component and binary melts are found using the proposed versatile procedure for determining kinetic parameters in processes involving phase transformations. These kinetic dependences on supercooling at the interface for the same single-component and binary melts are experimentally derived under comparable conditions in the formation and growth of single crystals and in a polycrystalline layer. A discrepancy between growth rates in a polycrystalline layer (constrained conditions) and for single crystals under the same supercooling is found. The rate of nucleation under constrained conditions is also lower. In practice, when calculating the process of crystallization, it is necessary to use kinetic parameters obtained for constrained conditions of the process. In studying the mechanism of crystal nucleation and growth, kinetic parameters derived for single crystals should be used.