Structure and Oxidation Behavior of NiAl-Based Coatings Produced by Non-Vacuum Electron Beam Cladding on Low-Carbon Steel

• Published in: Metals (Basel ) 2022-10, Vol.12 (10), p.1679
• Main Authors: Ogneva, Tatiana S., Ruktuev, Alexey A., Lazurenko, Daria V., Emurlaev, Kemal I., Malyutina, Yulia N., Golkovsky, Mikhail G., Egoshin, Kirill D., Bataev, Ivan A.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Carbon content; Carbon steel; Cladding; coating; Electron backscatter diffraction; electron beam cladding; Electron beams; Experiments; Grain growth; Grain size; Hardness; Intermetallic compounds; Low carbon steel; Low carbon steels; NiAl; Nickel aluminides; Nickel base alloys; Nickel compounds; Nuclear energy; Optical microscopy; Oxidation; Oxidation-reduction reaction; Oxide coatings; Petroleum; Refining; SEM; Spinel group; Steel products; Steel, Structural; structure; Substrates; Titanium alloys; XRD
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met12101679

NiAl-based intermetallic coatings were obtained using non-vacuum electron beam cladding on low-carbon steel. The structure of the coatings was investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). The coatings mostly consisted of grains elongated perpendicular to the substrates, with a strong texture along the grain growth direction. The coatings contained about 14 at. % Fe, which appeared due to the partial melting of the steel substrate. At the bottom of the coatings, an inhomogeneous mixing zone with an increased concentration of Fe was formed; at the “substrate–coating” interface, a thick layer with a Fe50-Ni25-Al25 at. % composition was observed. The samples exhibited weight gains of 0.1, 0.8, 2.14, and 3.4 mg/cm2 after 100 h of oxidation at 700, 800, 900, and 1000 °C, respectively. The oxide layer contained α-Al2O3 and θ-Al2O3, and the presence of iron atoms contributed to the formation of a small amount of spinel. During the oxidation process, a layer with a high Fe content (~60 at. %) formed along the boundary between the oxide film and the NiAl-based material, which had a positive effect on the formation of a non-porous “oxide–coating” interface.