Misorientation dependence of grain-boundary diffusion of Bi in Cu bicrystals

The boundary diffusion of bismuth has been investigated as a function of th e misorientation angle, for [001] and [011] twist boundaries and [001] and [011] symmetric tilt boundaries of Cu from observations of intergranularly fractured surfaces of Bi-doped bicrystals. It has been found that the misor ientation dependence of the boundary diffusivity of bismuth shows a close c orrelation with that of the boundary energy. The minimum of the boundary di ffusivity occurs where the cusps of the boundary energy exist. The larger d egree of disorder in the atomic arrangement at a boundary may result in the higher boundary diffusivity. The diffusion of bismuth in the [011] twist b oundaries has also been found to take place more easily than in the [001] t wist boundaries.