Abstract:Corrosion behavior of 2024 Al-Cu-Mg alloy of different tempers was assessed by potentiodynamic polarization studies in 3.5% NaCl solution, 3.5% NaCl+1.0% H₂O₂ solution and 3.5% NaCl solution at pH 12. Polarization curves showed shifting of corrosion potential (φ_corr) towards more negative potential with increasing ageing time and shifting of φ_corr in the positive direction with the addition of H₂O₂ in NaCl solution. Polarization curves in 3.5% NaCl solution at pH 12 exhibited distinct passivity phenomenon. Optical micrographs of the corroded surfaces showed general corrosion, extensive pitting and intergranular corrosion as well. Cyclic potentiodynamic polarization curves exhibited wide hysteresis loop and the mode of corrosion attack confirmed that the alloy states are susceptible to pit growth damage. Attempts were made to explain the observed corrosion behavior of the alloy of various tempers in different electrolytes with the help of microstructural features.

Key words: 2024 Al-Cu-Mg alloy; ageing behavior; electrochemical polarization; passivity; pitting potential