It was shown experimentally that, during annealing and creep under low applied stresses, matrix dislocation loops frequently cross-glide. The periodic length of the zigzag dislocations deposited in the interfaces was equal to that of the γ/γ'-microstructure. Initially, the zigzag dislocations move in the (001) interface by a combination of glide and climb but then they stop near the γ'-edges and align along 〈100〉. Reactions of such dislocations lead to the formation of square interfacial networks consisting of 〈100〉 oriented edge dislocations. The complex dislocation movement was explained by the inhomogeneity of the misfit stresses between γ- and γ'-lattices. The tensile components of the stress tensor drive the dislocations through the channel, whereas the shear components near the γ'-edges cause the zigzag movement and the 〈100〉 alignment. The total effect was the most efficient relaxation of the misfit stresses. The results were relevant, especially for single-crystal superalloys which have an increased γ/γ'-misfit due to the high level of refractory elements.

Inhomogeneity of Misfit Stresses in Nickel-Base Superalloys - Effect on Propagation of Matrix Dislocation Loops. T.Link, A.Epishin, B.Fedelich: Philosophical Magazine, 2009, 89[13], 1141-59