Electrochemical corrosion behavior of nanocrystalline copper bulk

The corrosion behavior of nanocrystalline (nc) copper bulk prepared by IGCWC (inert gas condensation and in situ warm compress) was studied in 0.1 mol/L CuSO4 + 0.05 mol/L H2SO4 solution. It was found that nc copper exhibited a corrosion behavior quite different from conventional coarse-grain copper. Nanocrystalline copper exhibited uniform dissolution of the surface and discrete localized corrosion typically, but conventional coarse-grain copper exhibited considerable preferential attack along the grain boundaries with signs of pitting corrosion dispersed throughout the surface uniformly. Compared with coarse-grain copper, nc copper decreased in resistance to corrosion. This decrease in corrosion resistance was mainly attributed to the high activity of surface atoms and intergranular atoms. The high activity of surface atoms and intergranular atoms, resulting from the reduction of grain size, leaded to an enhancement of passivation ability and to an increase of dissolution of passive film. In addition to the defects such as micro-gap produced in the fabrication of nc sample had great effect on the overall corrosion performance of nc sample, which were weakness to corrosion.