Pile-ups in thin foils: application to transmission electron microscopy analysis of short-range-order

• Published in: Philosophical magazine (Abingdon, England) England), 2004-03, Vol.84 (8), p.807-824
• Main Authors: Saada, G., Douin, J., Pettinari-Sturmel, F., Coujou, A., Clément, N.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Electron, ion, and scanning probe microscopy; Exact sciences and technology; Linear defects: dislocations, disclinations; Physics; Structure of solids and liquids; crystallography; Transmission, reflection and scanning electron microscopy(including ebic)
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430310001646718

The chemical force acting on dislocations in a short-range-ordered concentrated Ni-based alloy is investigated by post mortem and in-situ transmission electron microscopy. For this purpose, the positions of the dislocations in a pile-up are calculated, taking into account the stress relaxation at the free surfaces. The calculation shows that the distribution of the first dislocations of the pile-up is only slightly affected by the presence of the free surfaces, while the length of the pile-up strongly depends on the thickness of the foil. Analysis of pile-ups in two short-range-ordered Ni-based alloys shows that the chemical force resulting from short-range order (SRO) is noticeable up to the sixth dislocation of the pile-up. These results indicate the presence of very small short-range-ordered clusters, rather than a homogeneously distributed SRO.