Influence of Ar ion bombardment on the uniform corrosion resistance of laser-surface-melted Zircaloy-4

Zircaloy-4 specimens were surface treated by laser surface melting and/or A r ion bombarding. Corrosion tests were conducted in a 1N H2SO4 solution at room temperature and transmission electron microscope (TEM) was employed to analyze the change of microstructures in the surface layer. The potentiody namic tests showed that the corrosion current density, i(corr), was closely related to the surface condition, and it decreased with increasing the flu ence of Ar ions. After Ar ion bombardment, a significant improvement was ac hieved in the uniform corrosion resistance of laser-surface-melted Zircaloy -4 compared with that of the as-received Zircaloy-4. At the end, Gibbs free energy was used to explain why the fine grain structure and the fine dispe rsion of alloy components always led to the better uniform corrosion resist ance. (C) 1999 Elsevier Science B.V. All rights reserved.