Effect of Bi content on microstructure and corrosion behaviour of Zn–8Al–(Bi) alloys

Abstract

Electrochemical techniques such as Polarisation and Galvanic tests as well as immersion test were used to analyse both the effects of different Bi contents and the length scale of dendritic spacings on Zn-8 wt-%Al-(1.5, 2.3 and 3 wt-%Bi) alloys on their corrosion behaviour. The results revealed that no significant differences in the corrosion kinetics were observed with the scale of the dendritic and lamellar spacings. Conversely, the corrosion behaviour was shown to be dependent on the alloy Bi content. Despite the cathodic character of Bi, its addition to the Zn-8%Al alloy was shown to reduce the corrosion rate as compared with that of the binary alloy.