ON THE SOLUTE REDISTRIBUTION AT THERMALLY ACTIVATED PHASE-TRANSITION PROCESSES .1. THEORY

The main problem of the paper is the nature of the thermally activated phase transitions processes. A set of equations, based on the classical Turnbull equation for the migration of the phase boundary interface and the assumption that the system undergoes phase transition with minimal loss of energy, are obtained. The derived equations link together the processes of solute redistribution between the growing and the initial phases with the new phase growth rate. It can be shown that the equations so obtained are consistent with the ones obtained until now. In some cases the already existing equations are particular cases of the one derived in the present paper. The equations so obtained solved together with the heat and mass transport equations determine explicitly the process of the new phase growth.