Solidification and melting processes--one of the fundamental asymmetries in nature

摘要

Solidification and melting are phase transformations involving at least one liquid and' one solid phase, respectively. As compared to solidification, research work on melting documented in the literature is relatively scarce.' There are substantial differences between melting and solidification concerning nucleation, interface thermodynamics, solute rejection and absorption, structural aspects, etc. that all influence the phase transformation kinetics. A series of such differences is listed systematically. Recent progress in the description of solidification and melting with a consistent model is presented. For both rapid solidification and melting, kinetic effects yield that the T_0 line does not necessarily define the limiting case for complete solute trapping, there is rather a shift toward lower compositions for solidification and higher compositions for melting. As opposed to solidification where liquid and solid compositions enter the two-phase field in the phase diagram for rapid processes, for melting there is a certain velocity range where the liquid composition moves into the liquid field.