Chemical solvus

Figure 3.16 Solvus and spinodal decomposition fields as a function of elastic strain, (a) Strain-free or chemical solvus (b) strain-free spinodal (c) coherent solvus (d) coherent spinodal. From Ganguly and Saxena (1992). Reprinted with permission of Springer-Verlag, New York.

In Figure 15.3, two phases of composition b and c coexist within the solvus at 1000 K. Recall that the chemical potential of any one component must be the same in all coexisting phases at equilibrium. Therefore,... 

If a binary system exhibits a solvus (a composition region in which two solid solutions coexist at equilibrium see Figures 17.12, 17.21 for examples), a convenient way of determining Wq values is to use the fact that the chemical potential of each component is the same in every pair of compositions at the same T (and P) on each side of the solvus. For example if we know that compositions and on a symmetrical solvus are at equilibrium, then from Equation (10.94) we write... 

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