Surface analysis of argon-implanted zircalloy-2 and influence of bubble formation on the corrosion behavior

In order to simulate the irradiation damage, argon ions were implanted into zircalloy-2 alloy with a fluence ranging from 1×1016 to 1×1017 ions/cm2, using an implanter at an extraction voltage of 190 kV, at liquid nitrogen temperature. Then the effect of argon ion implantation on the aqueous corrosion behavior of zircalloy-2 alloy was studied. The valence states of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) was used to examine the microstructure of the argon-implanted samples. Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the argon ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircalloy-2 alloy in a 1 M H2SO4 solution. It was found that the bubbles were formed on the surface of implanted samples; the bubbles grew larger with increasing argon fluence. The microstructure of argon-implanted samples changed from amorphous to partial amorphous, then to polycrystalline and finally to amorphous. The bubble forming and changing and microstructure changes affected the corrosion properties of implanted samples. Finally, the mechanism of the corrosion behavior of argon-implanted zircalloy-2 alloy is discussed.