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 pressuriz ed water reactors, it was bombarded with 190 keV Zr+ ions at liquid ni trogen 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 spectros copy (AES) and X-ray photoelectronic spectroscopy (XPS) were employed to investigate the distribution and the valence of oxygen and zirconiu m ions inside the oxide films before and after bombardment. It was fou nd that: (1) the Zr+ ion bombardment enhanced the oxidation of Zircalo y-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 s ample; (2) the valence of zirconium ions in the oxide films was classi fied as Zr-0, Zr1+, Zr2+, Zr3+ and Zr4+ and the higher valence of zirc onium ions increased after the bombardment; (3) the irradiation oxidat ion damage function was established and (4) a regression formula descr ibing the relation between the oxidation weight gain and dpa (displace ment per atom) was obtained. (C) 1998 Elsevier Science B.V.