Diffusion-bonded bi-crystals with a cube-on-cube orientation, which contained (011) and (111) interphase boundaries, were used to study the effect of the boundary structure upon transport along the interfaces. It was demonstrated that the interfacial structures were reflected by the diffusion results. It was found that Ag* diffusion along anisotropic misfit dislocation arrays in (011) interphase boundaries was anisotropic, and was fastest along those channels which were associated with easy vacancy formation. The diffusion along morphologically stable (111) boundaries obeyed an Arrhenius relationship, with an activation energy of 92kJ/mol. A scatter in the diffusion data for (011) phase boundaries indicated that their structure, in complete contrast to that of the morphologically stable (111) interfaces, depended upon the thermal history of the specimens. This behavior was explained in terms of micro-faceting of the morphologically unstable (011) interphase boundary. Finally, Ag/Cu interdiffusion across the interface, at higher temperatures, created excess vacancies which then annihilated in the interface and reduced the anisotropy of diffusion along the interface.

T.Muschik, J.Sommer, C.Herzig, W.Gust: Materials Science Forum, 1993, 126-128, 407-10