Papers by Author: Nicole Clément

Abstract: In situ straining of microsamples have been carried out at different temperatures in a transmission electron microscope (TEM) to provide information about the elementary micromechanisms, which control the deformation in Ni-based superalloys at the nano and microscopic scales. The obstacles to the propagation of the dislocations have been identified and quantified when possible. The strengthening effect in the -matrix channels and the shearing of ' precipitates have been chosen to illustrate some results deduced from moving dislocation analysis. A quantitative evaluation of the stresses acting on dislocations has been performed. The shearing process of the ' precipitates at 850°C has been precisely analysed.

Abstract: An in situ study of the plastic deformation of <001> single crystals of an industrial superalloy has been performed at 850 °C in a TEM to observe directly the micromechanisms which control the deformation under the actual temperature and stress conditions experienced by this material in aeroengines. A comparison between the creation and propagation modes of moving dislocations in the standard microstructure after annealing and the rafted microstructure after 20 h of creep at 1050°C evidence the important role of the width of the γ channels as well as the strength of the γ/γ’ interface in controlling the shearing events of γ’ channels.