High temperature corrosion performance of FeAl intermetallic alloys in molten salts

The corrosion performance of FeAl base intermetallic alloys fabricated by spray-atomization and deposition during their immersion in molten sodium metavanadate (NaVO3), 80% (wt.%) sodium pentoxide (V2O5) +20% sodium sulfate (Na2SO4) and pure Na2SO4 in the temperature range of 600–1000 °C during 200 h was investigated. The experiments were realized by the weight loss method in the intermetallic alloys of composition FeAl40(at.%), FeAl40+0.1B and FeAl40+0.1B+10Al2O3. In all cases, the FeAl40+0.1B+10Al2O3 alloy showed the best corrosion resistance in the temperatures interval studied here. This behavior was discussed in terms of the formation of a protective Al2O3 layer and its dissolution by vanadate phases and internal sulfidation in the case of experiments carried out in pure Na2SO4. The morphology of the external layers and the corrosion products formed during the tests revealed that the corrosion rate of this type alloy depends on the corrosion compounds that are formed and the development of protective alumina scales.