A study on the corrosion behavior of 5083 aluminum magnesium alloy in the NaCl solutions of different pH by SECM

The corrosion behavior of 5083 aluminum magnesium alloy in the NaCl solutions of different pH was studied by the polarization curve method and the AC impedance spectroscopy in scanning electrochemical microscopy(SECM). The results show that in the acid system(pH3~7), with the increase of pH, the corrosion potential shifts positively, the pitting potential is of little difference, the current density reduces, and only one of the electrochemical impedance spectra has a tendency to shrink. At the same time, the impedance and phase angle decrease, the charge transfer resistance increases, and the corrosion resistance increases.In the basic system (pH 9~12), with the increase of pH, the corrosion current density increases gradually, and the corrosion potential decreases, and the corrosion rate increases from 0.000 9 mm/a to 0.025 6 mm/a. There are two capacitive arcs in the electrochemical impedance spectroscopy, showing an anti-arc at pH=12. Meanwhile, the impedance and phase angle decrease, dissolving process of the metal compound particles accelerates, and the corrosion resistance of the alloy reduces.