Fabricating corrosion-resistant FeAl coating used in liquid lead-bismuth eutectic by direct energy deposition

FeAl coatings were fabricated on 316 L stainless steel by direct energy deposition (DED) and evaluated in 550 °C liquid lead-bismuth eutectic (LBE) at different dissolved oxygen (DO) concentrations. The coatings formed stable and protective oxide film, demonstrating excellent corrosion resistance over the investigated DO concentrations (10 −7 and 10 −6 wt%). Thermodynamic analysis further reveals that oxidation is thermodynamically favored. Moreover, the low Al containing coatings form a porous inner Al 2 O 3 layer (IOL) accompanied by LBE penetration, leading to progressive film thickening during exposure. In contrast, the high Al containing coatings form a dense and continuous Al 2 O 3 IOL with negligible change in film thickness. The model predicts an approximate transition composition of 40.8 at% Al for the formation of a dense and continuous Al 2 O 3 IOL, while a higher theoretical value of 56.7 at% Al is predicted for the formation of a single continuous Al 2 O 3 layer. The FeAl coating can form protective Al 2 O 3 film and maintain structure stability in liquid LBE, exhibiting great potential for engineering application.