Microstructural study of the magnesium alloy (Az31) galvanostatically etched for different periods followed by copper electrodeposition in the alkaline copper-sulfate bath

A well adherent copper deposit on the Mg alloy (AZ31) can be obtained with a pretreatment with galvanostatic etching then followed by copper electrodeposition in an alkaline copper-sulfate plating bath. Experimental results show that the effect of galvanostatic etching on copper electrodeposition depends strongly on potential variation during anodic etching period. Oxygen-rich Cu and Mg layers were observed in the initial stage of galvanostatic etching. However, increasing the gavanostatic etching period to the potential plateau of its anodic polarization curve, the oxygen-rich Cu and Mg layers were almost removed and an activated surface of AZ31 can be achieved, which is suitable for Cu electrodeposition in the alkaline Cu-sulfate plating bath. The above-mentioned results were evidenced from the microstructure study with scanning transmission electron microscope.