Models of Diffusive Two-Phase Interaction

Because of the formation and growth of two-phase zones, the description of diffusion interaction in ternary and multicomponent systems is more complicated when compared to binary ones, in which the diffusion path in quasiequilibrium conditions is unambiguous and the resulting diffusion zone does not contain any two-phase regions. Diffusion processes in two-phase zones are difficult to 

It is possible to describe the growth of the two-phase zone if one knows the spatial and time change of the volume fractions of the phases and the concentrations of 

A phenomenological theory of these processes was proposed in [10]. Its main assumption is this one of the averaged concentrations is taken as the independent variable, corresponding to the existing single degree of freedom. The evolution equation 

To solve the equations one needs to determine the initial and boundary conditions. This involves some problems. If in a binary case of semi-infinite samples, the boundary concentrations are constant at the interfaces, in the case of three-component systems we cannot say for sure whether or not it is so. In [10] it 

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