Effect of Cu addition on microstructure and corrosion behavior of spray-deposited Zn-30Al alloy

In this study, one binary Zn-30Al and three ternary Zn-30Al-Cu alloys were synthesized by the spray atomization and deposition technique. The microstructures of the spray-deposited alloys were investigated by means of scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD). Immersion test, potentiodynamic polarization and electrochemical impedance measurements have been used to estimate the corrosion rate and the behavior. The results indicate that the 1 wt.% Cu addition to spray-deposited Zn-30Al alloy does not make significant change in microstructure. However, with the 2,4 wt.% Cu additions to the alloy, some epsilon-CuZn4 compounds with particle or irregular shapes were observed on the grain boundaries in the microstructures. Immersion test and electrochemical measurements confirmed that the 1 wt.% Cu addition displays superior corrosion resistance, whereas the 2,4 wt.% Cu additions have a baneful effect on the corrosion behavior. (C) 2011 Published by Elsevier B.V.