The anodic behaviour of freshly generated α-brass surfaces

Abstract 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.

[1]  T. Hoar,et al.  Yield-assisted anodic dissolution of brasses in ammoniacal solutions , 1971 .

[2]  E. Mattsson.  Stress corrosion in brass considered against the background of potential/pH diagrams , 1961 .

[3]  F. P. Ford.  Quantitative examination of slip-dissolution and hydrogen-embrittlement theories of cracking in aluminium alloys , 1978 .

[4]  J. Scully.  Mechanism of dissolution-controlled cracking , 1978 .

[5]  T. Hoar,et al.  The electrochemistry of the stress-corrosion cracking of alpha brass , 1965 .

[6]  F. P. Ford,et al.  Bare Surface Reaction Rates and Their Relation to Environment Controlled Cracking of Aluminum Alloys I . Bare Surface Reaction Rates on Aluminum‐7 Weight Percent Magnesium in Aqueous Solutions , 1980 .

[7]  M. Kermani,et al.  The effect of strain-rate upon stress corrosion crack velocity in α-brass in ammoniacal solutions☆ , 1979 .

[8]  T. P. Hoar,et al.  The potential/pH diagram for a copper-water-ammonia system: its significance in the stress-corrosion cracking of brass in ammoniacal solutions , 1970 .

[9]  G. T. Burstein,et al.  Anodic behaviour of scratched silver electrodes in alkaline solution , 1980 .

[10]  A. J. Forty.  Corrosion micromorphology of noble metal alloys and depletion gilding , 1979, Nature.

[11]  J. Newman.  Resistance for Flow of Current to a Disk , 1966 .

[12]  T. Hoar,et al.  Use of the scratching electrode technique to interpret the stress corrosion cracking behaviour of α-brass in ammoniacal copper sulphate solutions , 1980 .