Effect of Area Ratio on the Galvanic Corrosion of AZX611 Magnesium Alloy/A6N01 Aluminum Alloy Joint

Galvanic corrosion at the joint of AZX611 magnesium (anode) and A6N01 aluminum (cathode) in 1 mass% NaCl solution with different cathode/anode area ratios was evaluated. The galvanic potential was different depending on the area ratio. The anode galvanic current density increased with increasing the area ratio. Anode and cathode weight loss corrosion rates, and the average of anode current densities, were linearly related to the logarithm of the area ratio with different slopes. Scanning vibration electrode technology (SVET) has exhibited the presence of anode current spots that increased with the area ratio. Surface profile of the galvanic joint was in good agreement with the SVET results. The obtained effect of cathode/anode area ratio was analyzed by the mixed potential theory. Finally, the compatibility of magnesium/aluminum joint was compared with other dissimilar metal joints.