Oxidation of Zirconium after Argon Ion Irradiation

An oxidation of the near surface layers of pure zirconium samples resulting from ion irradiation in residual gas atmosphere of vacuum chamber was observed in the work. The irradiation was performed with 100 keV Ar+ ions at fluence of 1 x 10(17) cm(-2), temperature of the samples did not exceed 150 degrees C. An element analysis of the modified layers was carried out using Rutherford (RBS) and Resonant Elastic Backscattering Spectrometry (ResBS) of He-4 ions (resonance in O-16(He-4,He-4)O-16 scattering at about 3,045 MeV). A stoichiometric composition of the surface oxide film was found out related to ZrO2. The films were coloured in violet. A thickness of the oxide layer was measured to be about 660 nm, which is by about an order of magnitude greater than a value of the calculated projected range of Ar ions in Zr (Rp = 69,3 nm, SRIM2008 code). It is supposed that the oxidation has a linear (or destructive) character. The obtained results allow us to propose an alternative mechanism of the enhanced anticorrosion resistance of U, Zr, and its alloys after irradiation with He, Ar, Kr, Xe ions experimentally observed in the literary previously. A possible mechanism of the fast oxygen diffusion and formation of broad deep oxide layer was discussed.