Intrinsic diffusion and the Kirkendall effect in theNi-Pd (at 900-1200 deg C) and Fe-Pd (at 1 100 deg C) solidsolution systems were investigated. The diffusion coupletechnique including incremental and "multi-foil" couples wasemployed. A theoretical analysis of the Kirkendall effect, whichmanifests itself by migration of inert markers inside theinterdiffusion zone, was performed for a binary solid solutionsystem. It was demonstrated that depending upon the relativemobilities of the components in different parts of the interactionzone of such binary diffusion couples, the appearance of two ormore "Kirkendall" planes as marked by inert particles can beexpected. This phenomenon, which indeed was predicted and foundin the multiphase Ni/Ti diffusion couple, was not observed in theexperiments on the single-phase Ni-Pd and Fe-Pd systems. Thediffusion process in these binary systems exhibiting a minimum inthe liquidus curve was found to show special features with respectto the concentration dependence of the diffusion coefficients.
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