THERMODYNAMICS OF NONEQUILIBRIUM PHASE-TRANSFORMATIONS IN SELECTIVE DISSOLUTION OF HOMOGENEOUS BINARY-ALLOYS

The article deals with the thermodynamics of phase transformations (PT) in the surface layers of an alloy in selective dissolution (SD) of the electronegative component (ENC). The change of the thermodynamic state of the surface layer of an alloy in consequence of SD of the ENC is characterized by the magnitude A(s) = (partial derivative G(s)/partial derivative zeta(s))P,T,N(B)s, where G(s) is the excess free surface energy, zeta(s) is a parameter characterizing the selectivity of the process of dissolution, and N(B)s is the mole fraction of the component B in the surface layer of the alloy. This magnitude determines the probability of nonequilibrium phase transformations. It was established that the obtained conclusions agree qualitatively with the experimental data. The thermodynamic relations are interpreted on the basis of model concepts.