Electrochemical Corrosion Behavior of Iron Aluminides in Sulfuric Acid

Abstract

In the present work, samples of a binary intermetallic alloy (Fe3Al) with 26at.%Al were submitted to electrochemical corrosion evaluation in a 0.5M H2SO4 solution containing naturally dissolved oxygen. The corrosion resistance was evaluated by applying linear polarization, electrochemical impedance spectroscopy and potentiodynamic polarization at 22 and 35°C. The results obtained revealed that in both conditions the material exhibits active-passive behavior. Heating to 35°C did not alter the passivity characteristics of the alloy (passivation range and passive current density), but elevated the corrosion current density and the critical current density. The polarization resistance of the samples was also decreased with temperature, following the trend observed for the corrosion current density.

Archives of Foundry Engineering

“…The results show that Fe-25Al exhibits a lower resistance to uniform corrosion compared to the Fe-11Al alloy. The values obtained suggest similar corrosion resistance compared to previous reports concerning Fe3Al based Fe-Al-C alloys in sulfuric acid [6], but significantly lower corrosion resistance compared to the binary Fe-Al alloy, in agreement with [12]. The higher reaction rate observed for the Fe-25Al alloy were associated with a higher critical current density (icrt), indicating that a higher level of metal dissolution was observed prior to the formation of the passive layer.…”

“…electrolyte and explains the relatively elevated values for passive corrosion density observed in the present study in comparison to other investigations [12]. Observation of the oxide scales with larger magnifications, as shown in Figs.…”