Papers by Author: Mustafa Benyoucef

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.

Abstract: Cold-drawn Electrolytic Tough Pitch copper wires have been investigated with Neutron Diffraction and Electron Back Scattered Diffraction. The drawn copper wires (38% reduction in area) develop major <111> and minor <001> fiber textures. It appears that the texture intensity of the reinforcements within the <111> and <001> fibers is more pronounced in the center and intermediate part of the wires. During the first annealing time, it is found that the recrystallization kinetics is enhanced when oxygen content is increased. The recrystallized fraction within the intermediate zone of the wire is two times larger in the cathode with higher oxygen content. The mechanisms at the origin of this acceleration of recrystallization kinetics will be discussed taking into account the presence of Cu2O type oxides.

Abstract: The analysis of the microstructure deformation and the static recovery were investigated by transmission electron microscopy (TEM) observations, after cold drawing in copper. The observed microstructures according to the orientation of grains are composed of dislocation cells, deformation bands and dense dislocation walls. In <001> grains, the cells are equiaxed, regular and surrounded by sharp walls, whereas in the <111> grains the cell creation is also in progress. During the annealing, the microstructure of <001> grains evolves to a stable configuration composed of very thin walls and coalesced cells that correspond to the first recrystallization nuclei.