Effect of Sn ion implantation on electrochemical behavior of zircaloy-4

In order to study the effect of tin ion implantation on the aqueous corrosion behavior of zircaloy-4, specimens were implanted by tin ions with a dose range from 1×1016 to 5×1017 ions/cm2 at an extracted voltage of 40 kV. The valence and element penetration distribution of the surface layer were analyzed by X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES), respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the micro-morphology and microstructure of tin-implanted samples. When the dose is 5×1016 ions/cm2 or higher, a large number of small tin balls are produced in the implanted surface. The potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion resistance of zircaloy-4 in a 0.5 M H2SO4 solution. It was found that a significant improvement was achieved in the aqueous corrosion behavior of zircaloy-4 implanted with tin when the dose is 1×1016 ions/cm2. When the dose is higher than 1×1016 ions/cm2, the corrosion resistance of zircaloy-4 implanted with tin ions decreased compared with that of the as-received zircaloy-4. Finally, the mechanism of the corrosion behavior of the tin-implanted zircaloy-4 is discussed.