Helium Behaviour in Fe-Base Materials: Thermal Desorption and Nuclear Reaction Analyses
Polycrystalline Fe 99.95 and 99.5 samples were implanted with helium at 8 keV and 3 MeV. Thermal Desorption Spectroscopy (TDS) and Nuclear Reaction Analysis (NRA) provided a complementary set of techniques to characterize helium-materials interactions within two different implantation depths, respectively close to the surface and in the bulk. Using TDS, it was possible to get information about the nature and the states of the structures where helium was trapped in radiation damaged Fe specimens. Activation energies for every trapping site (mono-vacancies, clusters) have been determined from conventional reaction model. The effect of interstitial carbon was also discussed, and compared with previous ab-initio studies. Moreover, the helium bulk diffusion constants in radiation damaged structures could be derived from non destructive 3He depth profiling. Preliminary observations highlighted that a few part of He remained trapped while helium bubbles migrated in the bulk.
I. Bezverkhyy, S. Chevalier and O. Politano
H. Lefaix-Jeuland et al., "Helium Behaviour in Fe-Base Materials: Thermal Desorption and Nuclear Reaction Analyses", Defect and Diffusion Forum, Vols. 323-325, pp. 221-226, 2012