The mechanisms of dissolution and passivation of bulk polycrystalline icosahedral Al63Cu25Fe12 during electrolytic corrosion in 0.1 N NaOH and 1 N H2SO4 were studied in detail. In 1 N H2SO4 selective dissolution of Al and Fe occurs at the open circuit potential, which leads to a porous layer of recrystallized fcc Cu; after anodic polarization dissolution of the alloy is followed by redeposition of Cu and formation of Cu2O. In 0.1 N NaOH selective dissolution of Al was observed and a nanocrystalline layer consisting of Cu2O and FeOOH forms at the open circuit potential as well as during anodic polarization up to -150 mVSHE. At higher potentials Cu-ions dissolve into the electrolyte, which allows building up an Al-hydroxide layer. Presumably due to the loss of Al during polarization phase transforma-tions of the quasicrystals (e.g. continuous transformation or precipitation) were observed by transmission electron microscopy.

In order to clarify the influence of the quasicrystalline structure on the corrosion, open circuit potentials and current densities of the quasicrystalline and three ternary crystalline phases with different Al-content, but approximately constant ratio Cu:Fe of 2:1 were compared. Lower current densities, but a less noble open circuit potential for the quasicrystals than expected from the trend over the Al-content indicate a small influence of the quasicrystalline structure.