The influence of copper additions and aging on the microstructure and metastable pitting of al-mg-si alloys

The metastable pitting of 6xxx series aluminum alloys (Al-Mg-Si-(Cu)) as a function of Cu content and aging was studied. Potentiodynamic polarization and potentiostatic transients were performed to determine the electrochemical response of a family of 6xxx alloys based on a similar Si:Mg ratio. Additionally, the evolution of microstructure in all samples studied was also determined using transmission electron microscopy. The refinement in thickness of precipitates with the addition of Cu was shown to decrease the propensity for metastable pitting.