A physico-chemical approach was developed, which could be used in binary diffusion couples in order to the determine diffusion parameters of product phases with a wide homogeneity range, as well as phases with a narrow homogeneity range. It was demonstrated that this approach was basically equivalent to the diffusion-based treatment. However, the physico-chemical approach shed light on the chemical reactions which occurred during interdiffusion at the interphase interfaces. This theory could be applied to any binary system, and for any end-member condition, in order to explain single-phase or multiphase diffusion-controlled growth. The Ni–Al and Ag–Zn systems were considered here in order to calculate diffusion parameters according to the physico-chemical approach. It was evident from theoretical analysis and experimental evidence that, in the presence of a stable Kirkendall marker plane, the presence of duplex grain morphology was to be expected in a particular phase layer.

A Physico-Chemical Approach in Binary Solid-State Interdiffusion. C.Ghosh, A.Paul: Acta Materialia, 2007, 55[6], 1927-39