Effects of Trace Ga Content on Electrochemical Corrosion Resistance of Pure Al

The effect of trace amount Ga (0.02% to 0.06%) on the corrosion behavior of pure Al (99.99%, 4N) in NaCl solution was investigated by potentiodynamic polarization technique and EIS. The results showed that the open circuit corrosion potential and pitting potential of Al shifted to active (negative) direction with the increase of Ga content, while the corrosion rate and pitting occurrence factor increased. From EIS test, the calculated results showed that the resitivity of oxide film on pure Al decreased with the increase of Ga content. The effect of Ga on the degradation of corrosion resistance was rather small when the Ga content was below 0.03%.The Ga content should be kept less than 0.03% in the pure Al.