Impact of yttrium ion implantation on corrosion behavior of laser beam welded zircaloy-4 in sulfuric acid solution

In order to study the effect of yttrium ion implantation on the aqueous corrosion behavior of laser beam welded zircaloy-4 (LBWZr4), The butt weld joint of zircaloy-4 was made by means of a carbon dioxide laser, subsequently the LBWZr4 samples were implanted with yttrium ion using a MEVVA source at an energy of 40 keV, with a fluence range from 1 1016 to 4 1016 ions/cm2 at about 150 8C. Three-sweep potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion behavior of yttrium-implanted LBWZr4 in a 0.5 M H2SO4 solution. Scanning electron microscopy (SEM) was used to examine the surface topographic character of the yttrium-implanted LBWZr4 before and after the potentiodynamic polarization measurement. The valences of the carbon, yttrium, and zirconium in the surface layer were analyzed by X-ray photoemission spectroscopy (XPS). It was found that a significant improvement was achieved in the aqueous corrosion resistance of yttrium-implanted LBWZr4 compared with that of the un-implanted LBWZr4. The mechanism of the corrosion resistance improvement of the yttrium-implanted LBWZr4 is probably due to the addition of the yttrium oxide dispersoid into the zirconium matrix.