Diffusion-induced grain-boundary migration was studied in this hexagonal system by using various Zn bicrystals. It was established that the phenomenon was essentially the same as that which occurred in cubic alloy systems such as Cu-Zn and Fe-Zn. On the other hand, hexagonal crystals had cylindrically symmetrical elastic properties; which provided an opportunity to study the effect of varying the grain boundary structure under conditions of constant coherency strain. It was therefore possible to separate the effects of grain boundary structure and elastic anisotropy. This could not be done when using cubic crystals. An expression was derived, for the coherency strain in a thin layer on the surface, which was required in order to formulate the driving force in the coherency strain model for diffusion-induced grain-boundary migration; without using some of the approximations which were made in the cubic case.

A.H.King, L.Liang: Materials Science Forum, 1996, 207-209, 497-500