Criteria for Phase Suppression and Growth in an External Field

Criteria for Phase Suppression and Growth in an External Field 

In the previous sections, we analyzed the growth of phases that have already passed the nucleation stage. Now, let us consider the preceding, second phase of the process when the imposed electric field changes the diffusion interaction 

Let two intermediate phases with narrow homogeneity ranges A c, AP)c 1 exist between insoluble metals A and B on the phase diagram. Taking into account the results obtained in Chapter 3, the rates for phase growth from critical nuclei are equal to 

In order to define the criteria of phase suppression and growth, one should, as in Section 3.2, study all possible combinations ofsigns for the quantities (dA hx/dt)j and (dAP)%/dt)j. A positive sign of (dA /dt)j means the growth of phase layer starting from the critical nuclei size, and the negative one yields suppression of phase growth. 

The system of equations (Equation 8.38) for (dA /dt)j differs from the corresponding system when an external field is absent, by the substitution of qi by qi j) = qi — otii and q2 by q-zij) = qi — azj- In the absence of the field, diffusion phase competition is defined by the relation 

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