Dealloying behaviour of Cu–20Zr alloy in hydrochloric acid solution

The dealloying of the duplex-phase Cu–20Zr cast alloys and corresponding sputtered Cu–20Zr films (wt.%) in hydrochloric acid solution was investigated using electrochemical, chemical and surface analysis techniques. Results show that the dissolution mechanisms for the cast alloy and the films were strongly depended on the electrochemical activities of Zr and Cu in each phase in 0.1 mol/l HCl solution. When the potential was between the redox potentials of Cu/Cl−/CuCls and Zr/Zr4+, the dissolution is attributed to the selective removal of Zr atoms in the cast alloy and the sputtered films; when the potential was higher than the redox potential of Cu/Cl−/CuCls, Cu and Zr atoms in the samples dissolved simultaneously. In duplex-phase cast alloy, of Zr in the different phases in the alloy, Zr in the zirconium-rich phase was in preference to dissolve owing to its high electrochemical activities. Namely the selective phase attach firstly happens in the cast alloy. The study of the corrosion characteristic of sputtered films showed that Cu atoms reacted with Cl− ions in the solution and formed the corrosion product of Cu(I) and Cu(II) complex ions, which restrained the dissolution of Cu atoms.