Analytical electron microscopy study of Ni/Ni-8 mol% Ti diffusion couples

Analytical electron microscopy (AEM) has been applied to the interdiffusivity measurements and microstructural observations in Ni/Ni-8 mol% Ti diffusion couples. The high spatial resolution attained by AEM revealed that there is an effect of annealing atmosphere on the concentration profiles and microstructures within a range of several microns around the Kirkendall interface: the distortion of concentration profiles and the formation of Ti-rich particles and/or regions were observed near the interface. The interdiffusivities measured using the Sauer-Freise technique from the concentration profiles without the effect of annealing atmosphere were in good agreement with the reported values of the interdiffusivities and the impurity diffusivities of Ti in Ni, but were higher by an order of magnitude than the self-diffusivities of Ni in Ni. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.