A structural study of oxidation in a zirconia-toughened alumina fiber-reinforced Fe[sub 3]Al composite

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02657331· OSTI ID:6133087

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

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1. Polytechnic Univ., Brooklyn, NY (United States)

A zirconia-toughened alumina fiber-reinforced Fe[sub 3]Al-based intermetallic composite was fabricated by pressure casting. The chemical stability of the composite at 1100 C in vacuum and air was studied by optical, scanning, and transmission electron microscopy. Fiber/molten metal interaction during pressure casting resulted in the rejection of ZrO[sub 2], from the fiber into the molten metal. The fiber/matrix interface in the cast composite was in some areas covered with thin ZrC and Fe[sub 2]AlZr layers. Vacuum annealing resulted in the dissolution of Fe[sub 2]AlZr and precipitation of ZrC and (Ti, Nb)C particles within the matrix. The density of carbides was very low. Air annealing led to the oxidation of ZrC to ZrO[sub 2], Fe[sub 2]AlZr to a mixture of Al[sub 2]O[sub 3] + ZrO[sub 2] and preferential growth of [alpha]-Al[sub 2]O[sub 3] over the ZrO[sub 2]. Depletion of Al from the matrix as a result of oxidation gave way to the precipitation of (a) coarse (Fe, Al)[sub 2](Nb, Al) particles and (b) fine cuboidal-shaped particles within the matrix during slow cooling from the oxidizing temperature. Oxidation of the matrix ended with the conversion of Fe(Al, Cr) into (Fe, Al, Cr)[sub 2]O[sub 3]. The Fe[sub 2]O[sub 3] was observed to wet the grain boundaries of the Al[sub 2]O[sub 3] fiber, which resulted in the disintegration of the fiber. Zr-containing plate-like precipitates with a (10[bar 1]4) habit plane were occasionally observed in Fe[sub 2]O[sub 3]. Diffusion of oxygen through the fiber and/or the fiber/matrix interface is believed to be responsible for the rapid oxidation of the composite.

• OSTI ID: 6133087
• 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. 24:2; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
360604* -- Materials-- Corrosion
Erosion
& Degradation
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ANNEALING
CARBIDES
CARBON COMPOUNDS
CASTING
CHALCOGENIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
DATA
DIFFUSION
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
FABRICATION
FIBERS
HEAT TREATMENTS
INFORMATION
INTERFACES
INTERMETALLIC COMPOUNDS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MICROSCOPY
NUMERICAL DATA
OPTICAL MICROSCOPY
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PRECIPITATION
REINFORCED MATERIALS
SCANNING ELECTRON MICROSCOPY
SEPARATION PROCESSES
STABILITY
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
ZIRCONIUM CARBIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES