The effect of the grain boundary structure and of intergranular segregation upon the thermal stability of dislocations that were trapped at grain boundaries was investigated in bicrystalline samples. The results were explained in terms of grain-boundary diffusional properties which controlled the accommodation of extrinsic grain-boundary dislocations. It was shown that intergranular segregation affected relaxation processes, in grain boundaries, to a much greater extent than did the crystallography. In the present metal, the extrinsic grain-boundary dislocations were more stable in boundaries that exhibited high S segregation than in well-ordered boundaries with low segregation. Geometrical features such as the dislocation Burgers vector, and the orientation of dislocation lines in the grain-boundary plane, had to be taken into account when interpreting the stability of extrinsic grain-boundary dislocations.

W.A.Swiatnicki, L.Priester, M.W.Grabski: Materials Science Forum, 1996, 207-209, 773-6