Studies of the initial oxidation of Fe-Si alloys by AES, XPS, EELS, and LEED

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6049863

Lee, Y P

Thin oxide layers on polycrystalline Fe-8.75at % Si, and single-crystalline Fe-6.85at% Si (110) and (111) alloys were investigated by AES (including Ar/sup +/ and Xe/sup +/ depth profiling), EELS, XPS, and LEED during the initial oxidation stage at room temperature under very low oxygen pressure. It was observed that a very thin SiO/sub 2/-rich external layer is formed, as predicted by others, and established preferentially at the first stage of oxidation. A Si-depletion zone approx.5 A deep was found in the polycrystalline alloy with about 25% Si-depletion at the alloy/oxide interface. The formation of an Fe silicate-like structure just beneath the Si oxide-rich top layer down to the alloy/oxide interface was also observed. The rates of oxidation of polycrystalline alloys were determined to be retarded to approximately 40% of the rate of pure Fe after exposure to 200 L of O/sub 2/. The best annealing conditions for each single-crystalline alloy were determined to provide the cleanest surface for the following initial oxidation experiments. Annealing at approx. 55/sup 0/C for 20 min after Ar/sup +/ sputter-cleaning was found to be best for Fe-Si (110). The initial oxidation results for the single-crystalline alloys were compared with those of the polycrystal alloys to show a general resemblance in the various initial oxidation features.

• Research Organization: Iowa State Univ. of Science and Technology, Ames (USA)
• OSTI ID: 6049863
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
42 ENGINEERING
420500 -- Engineering-- Materials Testing
ALLOYS
ANNEALING
CHALCOGENIDES
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CRYSTALS
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
IRON COMPOUNDS
IRON SILICATES
LAYERS
MONOCRYSTALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
POLYCRYSTALS
SILICATES
SILICON ALLOYS
SILICON COMPOUNDS
SILICON OXIDES
TRANSITION ELEMENT COMPOUNDS