Potential-pH Diagrams for 90-10 and 70-30 Cu-Ni in Sea Water

The experimental potential-pH diagrams for 90-10 and 70-30 Cu-Ni in aerated, natural sea water at ambient temperature (25 C) have been derived using electrochemical hysteresis methods. The result is a definition of the potential and pH regions where these alloys are immune or susceptible to various forms of corrosion in sea water. Areas of immunity, general corrosion, passivation, and susceptibility to dealloying are defined for each alloy. Conclusions are drawn as to the differences in corrosion kinetics for 90-10 and 70-30 Cu-Ni in sea water, the former involving surface enrichment of nickel, and the latter passivation.