Effect of self-ion bombardment damage on high temperature oxidation behavior of Zircaloy-4

In order to simulate the oxidation behavior of Zircaloy-4 in pressurized water reactors, it was bombarded with 190 keV Zr+ ions at liquid nitrogen temperature up to a dose of 8 x 10(16) ions/cm(2) and was then oxidized in pure oxygen at 923 K and 133.3 Pa. Auger electron spectroscopy (AES) and X-ray photoelectronic spectroscopy (XPS) were employed to investigate the distribution and the valence of oxygen and zirconium ions inside the oxide films before and after bombardment. It was found that: (1) the Zr+ ion bombardment enhanced the oxidation of Zircaloy-4 and resulted in the oxidation weight gain at a dose of 8 x 10(16) ions/cm(2) which was four times greater than that of the unbombarded sample; (2) the valence of zirconium ions in the oxide films was classified as Zr-0, Zr1+, Zr2+, Zr3+ and Zr4+ and the higher valence of zirconium ions increased after the bombardment; (3) the irradiation oxidation damage function was established and (4) a regression formula describing the relation between the oxidation weight gain and dpa (displacement per atom) was obtained. (C) 1998 Elsevier Science B.V.