Incorporation processes of extrinsic dislocations in singular, vicinal and general grain boundaries in nickel

The relaxation of the stresses associated to grain boundary (GB) extrinsic dislocations is investigated by in situ transmission electron microscopy in nickel near-Σ=3 {1 1 1}, near-Σ=11 {3 1 1} and near-Σ=11 {3 3 2} GBs. The results show that the stress relaxation depends on the GB structure: in periodic GBs, it requires discrete interactions between intergranular dislocations; in non-periodic GBs, the widening of dislocation contrasts is attributed to a dislocation core spreading.