ON THE PASSIVATION CHARACTERISTICS OF A BETA-FEAL INTERMETALLIC COMPOUND IN SULFATE-SOLUTIONS

The corrosion and passivation behaviour of Fe-24 wt% Al intermetallic Compound has been studied in sulphate solutions using cyclic voltammet ry and potentiodynamic curves, combined with X-rav photoelectron spect roscopy (XPS). The voltammogramms performed in 0.5 M H2SO4 show the pe aks characteristic of the oxidation/reduction process of iron. The com parison of the anodic polarization curve of FeAl in acid solution with those of the pure elements shows the beneficial effect of Al when add ed to Fe in terms of both passive range and current density. At higher pH (6.0 and 13.6), the FeAl passivates spontaneously. Preliminary XPS studies of the passive films grown in air and anodically revealed coe xistence of iron and aluminium oxides, thus explaining the superior co rrosion resistance of iron aluminides compared to iron.