Theory of boundary diffusion controlled grain rotation in a ‘bamboo’ structure

Abstract

The theory of grain boundary diffusion controlled rotation of an orthogonal bicrystal about its common boundary has been extended to the case of cylindrical geometry. The analysis for this simple ‘bamboo’ geometry enables predictions to be made with a higher level of certainty than is usual for other diffusion controlled processes. Since bamboo structures are easy to fabricate, this suggests an indirect method of estimating boundary diffusion coefficients based on experimental measurement of rotation rates. A numerical analysis is presented and the dependence of the rotation rate on bending moment and wire radius is determined. The variation of the local stress and diffusion fluxes over the boundary is calculated. The conditions where experimental measurements are likely to provide a viable method of estimating grain boundary diffusion coefficients are predicted.