Effect of carbon on corrosion behaviour of Fe3Al intermetallics in 0.5 N sulphuric acid

Abstract Electrochemical corrosion behaviour of iron aluminides, produced by electroslag remelting technique, having the compositions (1) Fe–15.6Al–0.05C, (2) Fe–15.6Al–0.14C, (3) Fe–15.6Al–0.5C and (4) Fe–15.6Al–1C were investigated in 0.5 N H2SO4 media. Corrosion rates of these alloys were found to increase with carbon content. This was attributed to the preferential attack of the carbide phases. These alloys exhibited typical active–passive–transpassive behaviour. In addition, they displayed a secondary anodic current maxima during polarization. The resistance of aluminides to breakdown of passivity was assessed by varying addition of chloride ions in the same media.