Strain and stress build-up in He-implanted UO 2 single crystals: an X-ray diffraction study

Aurélien Debelle (1) , Alexandre Boulle (2) , Frederico Garrido (1) , Lionel Thomé (1)

1 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière
2 IRCER-AXE3 - IRCER - Axe 3 : organisation structurale multiéchelle des matériaux

The strain and stress build-up in 20-keV He-implanted UO 2 single crystals have been determined by means of X-ray diffraction through reciprocal space mapping, with the use of a model dedicated to the analysis of the strain/stress state of ion-irradiated materials. Results indicate that the undamaged part of the crystals exhibits no strain or stress; on the other hand, the implanted layer undergoes a tensile strain directed along the normal to the surface of the crystals and a compressive in-plane stress. The build-up of both strain and stress with He fluence exhibits a two-step process: (i) a progressive increase up to a maximum level of ~ 1% for the strain and ~-2.8 GPa for the stress, followed by (ii) a dramatic decrease. The origin of the strain and stress build-up is the formation of both self-interstitial defects and small He-vacancy clusters. The strain, and stress relief is tentatively attributed to the formation of extended defects (such as dislocations) that induce a plastic relaxation.

Mots clés: XRD; UO 2; radiation effects; elastic strain; He; defects

Domaines: Matériaux

Aurélien Debelle, Alexandre Boulle, Frederico Garrido, Lionel Thomé. Strain and stress build-up in He-implanted UO 2 single crystals: an X-ray diffraction study. Journal of Materials Science, 2011, 46 (13), pp.4683-4689. ⟨10.1007/s10853-011-5375-1⟩. ⟨hal-02193733⟩