저널

Copper electrodeposition on AZ91 Mg alloy was studied in views of preferential deposition on ${alpha}$- or ${eta}$- phases and how to achieve uniform deposition over the entire surface on ${alpha}$- and ${eta}$-phases in a cyanide solution. The inhomogeneous microstructure of AZ91 Mg alloy, particularly ${alpha}$- and ${eta}$-phases, was found to result in non-uniform deposition of zincate layer, preferential deposition of zincate on ${eta}$-phases, which leads to non-uniform growth of copper layer during the following electrodeposition process. The preferential depositions of zincate can be attributed to higher cathodic polarizations on the ${eta}$-phases. Pin-hole defects in the copper electrodeposit were observed at the center of large size ${eta}$-phase particles which is ascribed to gas bubbles formed at the ${eta}$-phases. The activation of AZ91 Mg alloy in hydrofluoric acid solution was used to obtain uniform growth of zincate layer on both the ${alpha}$- and ${eta}$-phases. By choosing an optimum activation time, a uniform zincate layer was obtained on the AZ91 Mg alloy surface and thereby uniform growth of copper was obtained in a cyanide copper electroplating solution.

Mg alloy;Copper electrodeposition;Zincate layer;