The damage clusters produced by low dose, 80 keV Ni⁺ and W⁺ heavy-ion bombardment of pure nickel; of two nichrome alloys (with 8% and 17%Cr); and of a ternary alloy and 321 stainless steel which have the same base composition (Fe/Ni10%/Cr17%) have been studied by means of transmission electron microscopy. In all cases where the defects could be identified with confidence they were found to be vacancy in nature. Most of the defects were identified as Frank loops, some of which had partially dissociated. The number of loops that were identified as dissociated and the average degree of dissociation were dependent on the stacking fault energy γ, being greater in the low-γ ternary alloy and the stainless steel than in the high-γ nickel and nichrome alloys. In the high-y materials a small proportion (< 5%) of perfect loops was also observed. Defect yield values were between a factor of 2 and 5 higher for W⁺ ion bombardment than for the corresponding Ni⁺ ion irradiations, but the effect on the mean defect size and cascade efficiency was much less pronounced. In the case of the Ni⁺ ion bombardment, the defect yields in the two nichrome alloys were lower than in pure Ni. No such effect was observed for the W⁺ ion irradiations, when defect yield and cascade efficiency values very similar to those of pure nickel were obtained. The defect yield in the W⁺ ion irradiated ternary alloy was considerbly smaller than in the nichrome alloys and there was a further major decrease in the stainless steel. These reductions in defect yields were not accompanied by a change in the mean defect size nor in the distribution of the defect sizes which were very similar in all the materials for irradiation by a given ion species. The defect yield in W⁺ ion irradiated Ni remained constant with increasing irradiation temperature up to ~450°C and then decreased sharply at higher irradiation temperatures. The defect yield in W⁺ ion irradiated Ni/Cr17% remained constant up to at least 500°C. Possible physical explanations for these results are discussed.

La famille des matériaux semiconducteurs III-N présente des propriétés adéquates pour diversesapplications que ce soit dans le domaine de l’optique ou de l’électronique. Certaines de ces applicationsconsistent à intégrer ces matériaux dans des environnements hostiles et notamment soumis à l’actiond’ions lourds à différentes énergies. Lors de cette thèse, le travail consistait tout d’abord à comprendrel’évolution microstructurale sous irradiation du substrat alpha-Al2O3, puis du film mince GaN, afin d’établirun profil de l’évolution de l’endommagement en fonction de la profondeur. Un comportement assezsimilaire concernant l’évolution des paramètres de maille a été observé pour les deux matériaux. Dansla direction parallèle à la trajectoire du faisceau d’ions, une importante augmentation du paramètre demaille a été mise en évidence tandis que peu de variations ont été relevées perpendiculairement à latrajectoire du faisceau d’ions. Les formations de couche amorphe pour l’alpha-Al2O3 et de couche fortementendommagée pour le GaN ont été observées en surface. Les épaisseurs de ces couches augmentent enfonction de la fluence, associé à l’augmentation des contraintes résiduelles au sein du matériau. Al’aide d’hypothèses et des différents résultats obtenus, deux profils d’endommagement en profondeuront été proposés. D’autre part, la nanoindentation a montré que les paramètres de dureté et de moduled’élasticité évoluent fortement sous irradiation en fonction de la fluence. / Nitride semiconductors are attractive materials for the development of optical and electronic devices.Some of these applications can expose materials to extreme environments and especially radiation ofheavy ions at different energies. In this thesis, the study focused first on behaviour evolution underirradiation of alpha-Al2O3 and then of GaN thin film, in order to establish a profile of damage evolution asfunction of the depth. Concerning lattice parameter, a similar behaviour was observed for both materials.An important increase of lattice parameter parallel to ion beam was highlighted while few variations wasnoted for the lattice parameter perpendicular to ion beam. Formation of amorphous layer for alpha-Al2O3and highly disordered layer for GaN were observed in surface. Layers thicknesses increase as functionof the fluence with an increase of residual stresses in material. Using different results and assumptions,two damage profiles as function of the depth have been proposed. In addition, nanoindentation hasshown hardness and modulus of elasticity parameter evolve highly under irradiation as function of thefluence.