Studies on the aqueous corrosion behavior and microstructure of zircaloy4 which has been subjected to high-dose Ar ion bombardment

In order to investigate the ion bombardment effect on the corrosion behavior of zircaloy4, the specimen surfaces were bombarded by Ar ion using an accelerator at an energy of 150 keV with a dose range from 3×1015 to 1×1017 ions/cm2 at liquid nitrogen temperature. Post-bombardment corrosion tests were conducted to rank the corrosion resistance of the resulting specimens by potentiodynamic polarization curve measurements in a 0.5 M H2SO4 water solution at room temperature. The vacancy profile induced by Ar ions bombardment was calculated using Monte Carlo simulation program SRIM 96, and measured by means of the slow positron annihilation spectroscopy (SPAS). The surface microstructures were examined using glancing angle X-ray diffraction (GAXRD). The potentiodynamic tests showed that with the bombardment dose increasing, the passive current density, closely related to the surface corrosion resistance, decreased firstly and increased subsequently. The mechanism of the corrosion behavior transformation was due to the amorphous phase formation firstly and the amorphous phase destruction and the polycrystalline structure formation in the bombarded surface subsequently.