RESTRICTED APPLICABILITY OF ONSAGER RECIPROCITY RELATIONS TO MODELS OF INTERFACE MOTION

Onsager's reciprocity relations have been applied to the motion of a p lanar interface in a phase transformation in a two-component system, i n order to provide a test of kinetic models of alloy solidification. A lthough applicable to such models in general, Onsager's relations yiel d no information for a subclass of models in which the thermodynamic d riving forces are linearly dependent to first order, as is the case fo r several models of alloy solidification including the continuous grow th model (CGM) of Aziz and Kaplan. As a consequence, experimental test s will likely be required to distinguish between these models. If the CGM is generalized to include diffusion in the growing phase, Onsager' s relations are applicable under some circumstances.