Quantitative analysis of dislocation pile-ups in thin foils compared to bulk

Pile-ups observed in short-range ordered γ-phase of nickel-base superalloys have been investigated using both post-mortem and in situ transmission electron microscopy experiments. The influence of the foil thickness on the pile-up length, on the distances between the dislocations and on the elastic interaction stresses experienced by them, is analyzed. The results using the approximation of an infinite medium or accurate calculations taking into account the elastic relaxation of the stress by the free surface are compared. The experimental positions of the dislocations are shown to be determined by these latter calculations with a good accuracy so that precise information about short-range order friction forces can be deduced.