Influence of aluminium and lead on activation of magnesium as anode

Mg-6%Al, Mg-5%Pb and Mg-6%Al-5%Pb (mass fraction) alloys were prepared by induction melting with the protection of argon atmosphere. Their electrochemical activations in different electrolyte solutions were investigated by galvanostatic test. The microstructures of these alloys and their corroded surfaces were studied by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. The results show that the activation of magnesium is not prominent when only aluminum or lead exists in the magnesium matrix, but the coexistence of the two elements can increase the activation. The activation mechanism of Mg-Al-Pb alloy is dissolving-reprecipitating and there is a synergistic effect between aluminium and lead: the precipitated lead oxides on the surface of the alloy can facilitate the precipitation of Al(OH)3, which can peel the Mg(OH)2 film in the form of 2Mg(OH)2·Al(OH)3 and activate the magnesium matrix.