The anodic behaviour of freshly generated α-brass surfaces

Potentiostatic scratching experiments have been carried out on copper and 70-30 brass electrodes in acid and neutral electrolytes. The results are compared with published measurements of stress corrosion crack velocities in α-brass in neutral ammoniacal solutions. The plateau crack velocity at low strain-rates can be accounted for by stoichiometric bare surface oxidation of the alloy components, but at high strain-rates it is necessary to invoke rapid bare surface dezincification. Charge analysis shows that zinc dissolution can occur from several alloy layers at > 5 A cm^?2 without appreciable anodic reaction of copper. Some features of the bare surface electrochemistry of copper are discussed.