Self-diffusion in naturally grown symmetrical  = 5 <001> tilt boundaries was studied by using 110mAg radio-tracers. This produced the first extensive set of self-diffusion data on oriented high-angle grain boundaries. A technique which was based upon the Bridgman method permitted the production of boundaries with a large area (8mm x 60mm). This allowed the measurement of the diffusion behavior parallel to, and perpendicular to, the tilt axis in specimens which were cut from the same bi-crystal. The diffusivity was measured, parallel and perpendicular to the tilt axis, at temperatures which ranged from 593 to 876K. The Arrhenius parameters which were determined for the  = 53.1 {012} grain boundary were found to be markedly lower (1.23 x 10-17m3/s, 37.4kJ/mol) than those for the  = 36.9 {013} boundary (6.44 x 10-13m3/s, 109.1kJ/mol). A slight anisotropy was found for the 36.9 boundary (table 1), but no anisotropy was observed for the 53.1 boundary (table 2). The results were explained in terms of a 3-dimensional model for the atomic structure in the grain boundary core region.

J.Sommer, C.Herzig, T.Muschik, W.Gust: Acta Metallurgica et Materialia, 1995, 43[3], 1099-107

Table 1

Self-Diffusion on  = 5,  = 36.9 {013} Ag Tilt Boundaries,

Parallel and Perpendicular to the <001> Tilt Axis