The strong cathodic protection effect of metallic Zn results in a
higher corrosion rate as compared to the unreacted 55 wt.% Al–Zn coating.
The reacted Al–Zn coating also provides a passivation behaviour because
of the formation of Fe–Al intermetallic compounds. Localized
corrosion is possible due to specific microstructure, as the Zn, which
provides cathodic protection, will be corroded much faster than Fe–Al
intermetallic compounds.