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Internal oxidized copper was tested by isothermal mechanical spectroscopy in a medium temperature range (300–600 K). Experimental results show the existence of a non-thermally activated effect at low temperature and of a relaxation peak at higher temperatures. The material microstructure was studied by combination of Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectrometry (EELS). The TEM study allowed us to investigate the distribution of fine spherical particles and the presence of particular network dislocations inside the grains. The EELS method was used to identify the nature of these fine particles as Cu2O. The internal friction has revealed a non thermally activated maximum occurring at 0.1 Hz for temperatures ranging from 290 K to 394 K, and a relaxation peak obtained after annealing at 573 K. This peak is stable after successive annealings at 723 K and 873 K. Comparison of the microstructure observations, their evolution with annealing and the evolution of the relaxation effect with annealing temperature enables us to interpret the phenomena described in this work: on the one hand, the microstructural characterisation using TEM and EELS allows us to assign the first effect to the result of a transformation of metastable Cu2O particles to CuO under the cyclic stress; on the other hand, the relaxation peak that does not change after high temperature annealing is linked with a particular stable dislocation network observed in many grains.

Internal oxidized copper was tested by isothermal mechanical spectroscopy in a medium temperature range (300–600 K). Experimental results show the existence of a non-thermally activated effect at low temperature and of a relaxation peak at higher temperatures. The material microstructure was studied by combination of Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectrometry (EELS). The TEM study allowed us to investigate the distribution of fine spherical particles and the presence of particular network dislocations inside the grains. The EELS method was used to identify the nature of these fine particles as Cu$_{2}$O. The internal friction has revealed a non thermally activated maximum occurring at 0.1 Hz for temperatures ranging from 290 K to 394 K, and a relaxation peak obtained after annealing at 573 K. This peak is stable after successive annealings at 723 K and 873 K. Comparison of the microstructure observations, their evolution with annealing and the evolution of the relaxation effect with annealing temperature enables us to interpret the phenomena described in this work: on the one hand, the microstructural characterisation using TEM and EELS allows us to assign the first effect to the result of a transformation of metastable Cu$_{2}$O particles to CuO under the cyclic stress; on the other hand, the relaxation peak that does not change after high temperature annealing is linked with a particular stable dislocation network observed in many grains.

Copper and copper-aluminium solutions have been studied by means of high-temperature isothermal internal friction experiments performed between 10-4 and 10 Hz, in the temperature range 370-680°C. An enlarged internal friction peak superimposed on an exponential low-frequency background has been observed in each case. Such damping peaks are attributed to dislocation motion inside the grains. Activation energies are deduced from the peak position shifts as a function of the temperature. Possible rate-limiting mechanisms are suggested and discussed.

A new surface treatment technique by primary explosive was used on a 316L type austenitic stainless steel. Two explosive compositions, inducing a pressure of 1 GPa and 4 GPa respectively, were deposited in a thin layer on plane samples. The detonation induced effects have been characterized by different techniques. The surface roughness increases with the applied pressure, but remains lower than that obtained after shot peening. The microbardness profiles along a direction perpendicular to the treated surface and the microstructural study exhibit a marked hardening on several hundred micrometers associated with a profuse twinning. Moreover, for the 4 GPa pressure a very thin surface layer of fine recrystallized grains appears. In both cases, tensile residual stresses are measured at the surface and compressive stresses beyond 10??m. The microstructure in the surface layers results of a noticeable thermal effect. The wear resistance of this stainless steel is improved by a factor 10 to 200 depending on the treatment conditions. Une technique de traitement de surface utilisant un explosif primaire a ?t? utilis?e sur un acier inoxydable aust?nitique de type 316L. Deux compositions explosives d?livrant des pressions respectives de 1 GPa et 4 GPa ont ?t? d?pos?es en couche mince sur des ?chantillons plans. Les effets induits par la d?tonation ont ?t? caract?ris?s par diff?rentes techniques. La rugosit? en surface augmente avec la pression appliqu?e mais reste tr?s inf?rieure ? celle obtenue apr?s grenaillage. Les profils de microduret? suivant un axe perpendiculaire ? la surface trait?e et l'?tude microstructurale montrent un ?crouissage marqu? sur quelques centaines de microm?tres associ? ? un maclage important auquel s'ajoute, pour la pression de 4 GPa, une fine recristallisation en surface. Dans les deux cas, les contraintes r?siduelles sont de tension en surface et passent en compression au-del? de 10??m. La microstructure des couches superficielles t?moigne d'un effet thermique notable. La r?sistance ? l'usure de cet acier est am?lior?e d'un facteur 10 ? 200 suivant les conditions de traitement.