A discrete dislocation model was used to study the interactions of γ-channel dislocations in the γ/γ’ microstructures of superalloy single crystals. Three types of γ-channel were considered: octahedral face-centered cubic slip systems and 2 macroscopic crystallographic shear-loading conditions. It was found that various types of γ-channel differed with respect to the number of dislocations which could enter the channels. This effect became more important in the presence of misfit stresses. The latter were integrated into the analysis by performing preliminary thermo-elastic misfit-stress calculations which served as input for calculating the overall stress state. The other inputs to the overall stress state were the stresses associated with external loading, and the dislocation stress fields. The effect of the overall stress state was evaluated by considering the Peach–Koehler force which acted on a central channel dislocation. The results demonstrated that it was insufficient to consider dislocation plasticity, in γ/γ’ microstructures, merely on the basis of external resolved shear stresses. It was shown that misfit stresses, which attracted dislocation loops from one microscopic crystallographic slip system into one type of γ channel, made it more difficult for the same dislocations to enter other γ channels.

Dislocation Interactions in γ-Channels between γ’-Particles of Superalloy Single Crystals. M.Probst-Hein, A.Dlouhy, G.Eggeler: Materials Science and Engineering A, 2001, 319-321, 379-82