It was recalled that, when 2 alloys were placed in contact to form a diffusion couple, the microstructure which formed was a function of the alloy composition. This could be illustrated by using an interdiffusion microstructure map. Such maps were described here for binary and ternary diffusion couples which comprised 2 phases. It was found that the map was divided into regions, by phase boundaries. These regions were further sub-divided into fields wherein 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 original alloys.

Interdiffusion Microstructure Maps for Two Phase Diffusion Couples. J.E.Morral, H.Chen, F.Meisenkothen: Solid State Phenomena, 2001, 72, 105-9