It was noted that, when 2 alloys were placed in contact as a diffusion couple, the microstructure which formed was a function of the alloy composition. This could be depicted by a so-called interdiffusion microstructure map. Such maps were described here for the cases of binary and ternary diffusion couples which contained 2 phases. It was found that the map could be divided, into various regions, by phase boundaries. These regions could be further sub-divided into fields within which specific microstructures occurred. The boundaries that sub-divided the regions had an unexpected topology in that they could contain 3- or 5-line nodes; depending upon the phases in the initial alloys.

Interdiffusion Microstructure Maps for Two Phase Diffusion Couples. J.E.Morral, H.Chen, F.Meisenkothen: Solid State Phenomena, 2000, 72, 105-10