Dissolved-Oxygen-Induced Intensive Pitting Corrosion of Amorphous ZrCu Alloys in Thin NaCl Solutions

Abstract

Intensive pitting corrosion of amorphous (a-) Zr₅₅Cu₄₅ and a-Zr₅₀Cu₅₀ were observed by immersion in 0.2–200 mM NaCl solutions open to air at room temperature. The decreased corrosion rate in Ar-purged NaCl solution and no corrosion in ultrapure water open to air suggested that dissolved O₂ and Cl⁻ played an important role on the corrosion of the ZrCu-base amorphous alloys. The open-circuit potential showed a negative shift with increasing the NaCl concentration from 0.2 to 200 mM like that of pure Cu. These observations suggest that the corrosion of the ZrCu-base amorphous alloys in the NaCl solutions was triggered by Cu dissolution which was induced by the reduction of dissolved O₂. The dissolution of Cu and Zr self-catalytically progressed by the local concentration of Cl⁻ and hence the corrosion pits and holes were intensively formed even at the thinner NaCl concentrations.