Zirconium-ion implantation of zircaloy-4 investigated by slow positron beam

The effect of Zr-ion implantation into zircaloy-4 and the defect recovery was investigated by slow positron beam. Specimens were implanted by zirconium ions with doses ranging from 1 x 1015 to 1 x 1017 ions/cm2 using a MEVVA source at an extract voltage of 50 kV. It was found that defects in the samples irradiated with a dose above 1 x 1016 ions/cm2 has been recovered during the implantation process, and the thickness of oxide layer increases as indicated by auger electron spectroscopy (AES)measurements. Meanwhile, the defects in the sample implanted with a dose of 1 x 1015 ions/cm2 turns out to be recovered after annealing at 300 degree C in high vacuum for 1 hour,showing the corresponding the recovery energy of defects is very low. We propose the method of keeping the material at an appropriate temperature during implantation to improve the corrosion resistance of Zr-4 alloy, according to the relationship between the defect concentration and the corrosion resistance. (authors)