Equilibrium phase diagrams. See

Similar to the dealloying behavior of other intermediate phases such as e-Ag—Cd [18], the selective dissolution of In from a y-Sn-In electrode with composition Sii8oIn20 was shown to result in a phase transformation with the Sn-rich terminal solid solution (f-Sn) as a product phase. Because of the close structural relationship of the parent and product phases this y-Sn-In — 8-Sn phase transformation is expected to produce negligible volume constraints [19]. Therefore, it should fulfill Wagner s criteria of diffusion driven phase transformations [20,21], that is, (1) a plane (stable) interface between the product and parent phase develops, (2) the interface advances into the parent phase with a parabolic rate law, and (3) the composition of both phases at this interface is given by the equilibrium phase diagram (see Fig. 3). These expectations have been confirmed both by metallography and by electron beam microanalysis [13]. 

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