The air oxidation of yttrium ion implanted zircaloy-4 at 500 degrees C

The beneficial effect of yttrium ion implantation on the oxidation behavior of zircaloy-4 at 500 degrees C has been investigated. Zircaloy-4 specimens were implanted by yttrium ions with a dose range from 1 x 10(16) to 1 x 10 (17) ions/cm(2) at about 120 degrees C, and then oxidized in air at 500 deg rees C for 100 min. The valence of the oxides in the scale was analyzed by X-ray photoemission spectroscopy (XPS). Glancing angle X-ray diffraction (G AXRD) was employed to examine the phase transformation due to the yttrium i on implantation in the oxide films. The addition of yttrium changed the pha se in the scale from monoclinic zirconia to tetragonal zirconia. The measur ement of weight gain showed that a significant improvement was achieved in the oxidation behavior of yttrium ion implanted zircaloy-4 compared with th at of the as-received zircaloy-dr. The mechanism of the improvement was dis cussed. (C) 2000 Elsevier Science B.V. All rights reserved.