A study of the structure and the morphology of oxide films on amorphous Al-Fe-Ce alloys by XPS and SEM
- Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Division
- Argonne National Lab., IL (United States)
Aluminum-based metallic glasses are of technological importance due to their high strength, low density, and anticipated high resistance to corrosion. The authors report on the corrosion characteristics of melt-spun ribbons of Al{sub 90}Fe{sub 10{minus}x}Ce{sub x} (x = 3, 5, and 7). The amorphous alloys showed excellent corrosion properties in aqueous NaCl. The authors have also examined the composition, structure, and morphology of the native and passive oxide films using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and angle-resolved XPS. They show that the composition of the native oxide film is that of AlO{sub x}(OH){sub y}. The thickness of the native oxide is estimated from angle-resolved XPS data to be about 1.6 to 3.1 nm (i.e., nanometer). Passive films were formed in 0.9 weight percent (0.15M) NaCl solution by potentiostating below the pitting potential for 30 and 60 min. The passive oxide films contain oxidized Al, Fe, and Ce. The chemistry of Al in the passive oxide films is also that of AlO{sub x}(OH){sub y}. Iron appears to be present in the passive film as Fe{sub 3}O{sub 4} and Fe{sub 2}O{sub 3} and/or FeOOH with varying mole fractions depending on alloy composition. Cerium in the passive film appears to be present in the +3 oxidation state as Ce{sub 2}O{sub 3} or Ce(OH){sub 3}. A small fraction of Ce in the passive film of Al{sub 90}Fe{sub 3}Ce{sub 7} is present in the +4 oxidation states as CeO{sub 2}.
- OSTI ID:
- 82925
- Journal Information:
- Journal of the Electrochemical Society, Vol. 142, Issue 6; Other Information: PBD: Jun 1995
- Country of Publication:
- United States
- Language:
- English
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