The chemical force acting on dislocations in a concentrated short-range ordered Ni-based alloy was investigated by means of in situ transmission electron microscopy. The positions of the dislocations in a pile-up were calculated; taking account of stress relaxation at the free surfaces. The results showed that the distribution of the first dislocations of the pile-up was only slightly affected by the presence of the free surfaces. The length of the pile-up depended strongly upon the thickness of the foil. Analyses of pile-ups in 2 short-range ordered Ni-based alloys showed that the chemical force which resulted from short-range order was noticeable up to the sixth dislocation of the pile-up. The results indicated the presence of very small short-range ordered clusters, rather than an homogeneously distributed short-range order.

Pile-Ups in Thin Foils - Application to Transmission Electron Microscopy Analysis of Short-Range Order. G.Saada, J.Douin, F.Pettinari-Sturmel, A.Coujou, N.Clément: Philosophical Magazine, 2004, 84[8], 807-24