Microstructural observations on the oxidation of gamma-prime-Ni3Al at low oxygen partial pressure

Journal Article · Mon Jun 01 00:00:00 EDT 1992 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(92)90432-E· OSTI ID:7069393

Schumann, E; Schnotz, G; Trumble, K P; Ruehle, M ^[1]

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1. Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

Electron microscopy is used to investigate microstructural development during the oxidation of the 001-plane-oriented gamma-prime-Ni3Al single crystals at 1223 K under an oxygen partial pressure of 4 x 10 exp -19. After 1-min oxidation, TEM cross sections revealed a continuous 4-nm-thick film of gamma-Al2O3 with equiaxed 20-nm protrusions into the metal. Continued oxidation resulted in thickening of the gamma-Al2O3 scale, no grain growth, and the development of a plane metal/gamma-Al2O3 interface. Depletion of Al from the adjoining metal resulted in a well-defined disordered zone of Ni-Al solid solution between the Al2O3 scale and the gamma-prime-Ni3Al. After 5-h oxidation, large randomly oriented alpha-Al2O3 grains nucleated at the metal/gamma-Al2O3 interface, growing inward and transforming from the gamma-Al2O3 outward. The alpha-Al2O3 contained intragranular and intergranular voids. The gamma-Al2O3 exhibited a high density of planar defects and the interface between the gamma-Al2O3 and alpha-Al2O3 contained many voids. Voids were never observed at the metal/oxide interface. 19 refs.

• OSTI ID: 7069393
• Journal Information: Acta Metallurgica et Materialia; (United States), Vol. 40:6; ISSN 0956-7151
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
MICROSTRUCTURE
OXIDATION
NICKEL ALLOYS
ELECTRON MICROSCOPY
GRAIN SIZE
INTERMETALLIC COMPOUNDS
MONOCRYSTALS
PARTIAL PRESSURE
SUPERLATTICES
ALLOYS
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
CRYSTALS
MICROSCOPY
SIZE
360102* - Metals & Alloys- Structure & Phase Studies
360105 - Metals & Alloys- Corrosion & Erosion