High-temperature oxidation resistance of sputtered micro-grain superalloy K38G. [Ni-16. 3Cr-8. 4Co-4. 01Al-3. 81Ti-2. 7W-1. 8Mo-1. 75Ta-0. 76Nb]

Journal Article · Thu Oct 01 00:00:00 EDT 1992 · Oxidation of Metals; (United States)

DOI:https://doi.org/10.1007/BF00666917· OSTI ID:6999964

Hanyi, Lou; Fuhui, Wang; Bangjie, Xia; Lixin, Zhang ^[1]

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1. Corrosion Science Lab., Shenyang (China)

The oxidation of sputtered and cast superalloy K38G specimens was studied. The sputtered alloy was microcrystalline, with an average grain size [lt]0.1 [mu]m. The mass gains of the sputtered alloy were much less than those of the cast alloy at 800, 900, and 1,000C up to 500 hr, and were even less than those of pack aluminide on the cast alloy. K38G is a chromia-forming cast nickel-base superalloy, so the oxide scale formed on it is composed of Cr[sub 2]O[sub 3], TiO[sub 2], Al[sub 2]O[sub 3],and a spinel. The oxide scale formed on the sputtered alloy was Al[sub 2]O[sub 3]. This scale is thin, compact, and adherent. This result implied that microcrystallization reduced the critical aluminum content necessary to form alumina on the surface of this superalloy. No oxide spallation, as typically observed for cast of aluminized alloys, occurred on the sputtered superalloy. The reduction of the critical aluminum content for the formation of alumina and the improvement of the spallation resistance may be attributed to the microcrystalline structure formed during sputtering. The numerous grain boundaries favor outward aluminum grain-boundary diffusion, provide increased nucleation sites, and reduced stresses in the oxide scales.

• OSTI ID: 6999964
• Journal Information: Oxidation of Metals; (United States), Journal Name: Oxidation of Metals; (United States) Vol. 38:3-4; ISSN OXMEAF; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COATINGS
COBALT ALLOYS
CORROSION RESISTANCE
CRYSTAL STRUCTURE
DIFFUSION
ELECTRON MICROSCOPY
FRACTURE PROPERTIES
GRAIN BOUNDARIES
GRAIN SIZE
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
KINETICS
MATERIALS
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
MINERALS
MOLYBDENUM ALLOYS
MORPHOLOGY
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ADDITIONS
NIOBIUM ALLOYS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PROTECTIVE COATINGS
REACTION KINETICS
SCANNING ELECTRON MICROSCOPY
SIZE
SPECTROSCOPY
SPINELS
SPUTTERING
STRESSES
TANTALUM ALLOYS
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
TITANIUM ALLOYS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN ALLOYS
X-RAY SPECTROSCOPY