Oxidation behavior of single-crystal Al[sub 2]O[sub 3]-fiber-reinforced Ni[sub 3]Al-based composites

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

OSTI ID:7085109

Nourbakhsh, S; Rhee, W H; Sahin, O; Margolin, H ^[1]

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1. Polytechnic Univ., Brooklyn, NY (United States). Dept. of Materials Science and Engineering

A series of single-crystal Al[sub 2]O[sub 3]-fiber-reinforced Ni[sub 3]Al-based intermetallic matrix composites were fabricated by pressure casting. The matrices employed were binary Ni[sub 3]Al, Ni[sub 3]Al-0.5 at. pct Cr, and Ni[sub 3]Al-0.34 at. pct Zr. The development of microstructure upon oxidation in air at either 1,100 C or 1,200 C was investigated by optical, scanning, and transmission electron microscopy. In air-oxidized binary Ni[sub 3]Al, some of the fibers were fully or partially covered with a layer of oxide. A weak fiber/matrix bond in this system, which led to fiber debonding during composite processing, is believed to be responsible for the ingress of O into the composite and oxidation of the matrix in the debonded regions at the fiber/matrix interface. Addition of Cr to Ni[sub 3]Al resulted in an almost threefold increase in fiber/matrix bond strength. No oxidation of the interface was observed. A thick layer of oxide was formed around all the fibers when the composite was thermally cycled prior to isothermal annealing. Addition of Zr to Ni[sub 3]Al resulted in the formation of a layer of ZrO[sub 2] on the surface of the fibers during composite processing. The ZrO[sub 2] layer provided a fast path for the diffusion of O, which led to the formation of a rootlike oxide structure around the fibers. The rootlike structure consisted of a network of Al[sub 2]O[sub 3]-covered ZrO[sub 2].

• OSTI ID: 7085109
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:7; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360604* -- Materials-- Corrosion
Erosion
& Degradation
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM ADDITIONS
CHROMIUM ALLOYS
COMPOSITE MATERIALS
DATA
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
MATERIALS
METALLURGICAL EFFECTS
METALS
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
TRANSITION ELEMENTS
ZIRCONIUM
ZIRCONIUM ADDITIONS
ZIRCONIUM ALLOYS