Diffusion studies were described which highlighted some unusual diffusion structures and diffusion paths which were observed in the single-phase and multiphase diffusion couples of ternary systems. The studies included diffusion couples which involved refractory metals such as Mo, W and Re that were in contact with MoSi2 at 900 to 1700C. Couples in the Fe-Ni-Al system were also investigated at 1000C. The development of non-planar morphologies was demonstrated for both binary and ternary silicide layers. Examples of up-hill diffusion and zero-flux plane development, without the formation of a relative extremum in the concentration profiles, were presented for Mo in ternary diffusion layers. They were explained in terms of the relative magnitudes of the main and cross ternary interdiffusion coefficients. A double serpentine path in a single-phase couple, and de-mixing of 2-phase layers in a multiphase couple, were also illustrated. The diffusion paths and structures were explained in terms of ternary interdiffusion coefficients and diffusional interactions between components.

Diffusion Structures and Diffusion Paths in Ternary Systems - Selected Unusual Observations. M.A.Dayananda: Solid State Phenomena, 2000, 72, 123-34