Atomic transport in B2-ordered Al(Fe,Ni) alloys: Tracer-interdiffusion couple approach

A novel tracer-interdiffusion couple technique is utilized to measure the concentration-dependent tracer- (Fe-59) diffusion coefficients in the B2-ordered Al-50(Ni,Fe)(50) alloys at 1373 K in a single experiment. The influence of variable molar volume on the diffusion coefficients is examined. The tracer diffusion coefficients determined under chemical gradients are shown to be in an excellent agreement with the diffusivities measured independently for homogeneous alloys. The tracer diffusion coefficients of Fe are observed to increase strongly with an increase of the Fe concentration. Strong up-hill diffusion of Al hinders a reliable determination of the interdiffusion coefficients with a single diffusion couple. The results confirm a high potential of the tracer-interdiffusion couple technique for producing highly accurate concentration-dependent mobility data in multi-component systems.