Thermal stability of extrinsic dislocations in near ∑11 grain boundaries in nickel

摘要

Thermal stability of the extrinsic grain boundary dislocations (EGBDs) in near ∑11 grain boundaries (GBs) has been investigated in nickel bicrystal thin foils containing different levels of impurities. The geometrical (GB misorientation and plane-GB steps) and chemical (segregation) factors which may Affect the EGBD relaxation have been considered. The results show that the EGBD accommodation kin- Etics depends strongly on the segregation level, related to the GB plane orientation, and on the EGBD line Orientation in the GB plane. They are mainly interpreted in terms of intergranular diffusion. They support The conclusion that no geometrical criterion can predict GB behavior, particularly in presence of GB segre- Gation.