Résumé. 2014

The aim of this work was to examine if a chemical anisotropy around y' precipitates could be induced by the applied stress a t the beginning of a compressive creep test. This question was solved in terms of concentration profiles around j in order to see which alloying elements diffuse and if they do, in which direction. The results were discussed in the light of finite element simulations where the local stress states were determined in terms of equivalent Von Mises stress and hydrostatic pressure. [U A. FREDHOLM, PhD Thesis-Ecole des Mines de Paris (1987) [2] D. OSSO, DEA-INSTN-Orsay (1991)

Abstract. A three-dimensional finite element (F.E.) model is used to estimate the mismatch stresses at a microscopic scale in y -y ' single-crystal nickel-based snpedloys. F.E. calculations point out the specificity of stress/strain distributions in these alloys, in particular the fact that internal stresses concentrate in the connected y matrix. The analysis of stress/strain fields and elastic energy evolution as a function of precipitate morphology and volume fraction allows to explain some atypical precipitate shape changes such as "splitting" during precipitation treatments or "raftening" during high temperature creep tests.