Interfacial reactions in COMRAL-85 metal matrix composite

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:143657

Drennan, J ^[1]; Xia, K; Couper, M J ^[2]

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1. CSIRO, Clayton, Victoria (Australia). Division of Materials Science and Technology
2. Camalco Research Center, Thomastown, Victoria (Australia)

The enhancement of mechanical properties in metal matrix composites is related to the nature of the interfacial layer between the reinforcement and the matrix. The interfacial layer in COMRAL{trademark}-85 composite has been investigated. In this composite, the aluminum alloy matrix 6061 is reinforced with polycrystalline, fine-grained alumina-containing microspheres. Analytical scanning and transmission electron microscopy have been used to determine the primary phases in the microspheres and to characterize the interfacial layer. The microspheres were shown to contain mainly two phases, mullite (Al{sub 6}Si{sub 2}O{sub 13}) and alumina ({alpha}-Al{sub 2}O{sub 3}) with grains of each phase typically less than 0.5{mu}m in size. A layer of spinel with thickness less than about 0.5{mu}m was found at the matrix/reinforcement interface. Spinel crystals (MgAl{sub 2}O{sub 4}) were observed at both the aluminum/mullite and aluminum/alumina interfaces. The spinel phase apparently grows at the expense of the mullite or alumina grains, with instances of curved or stepped growth fronts. The spinel phase appears to nucleate from multiple sites on individual grains of the reinforcement. Several reactions which might govern the formation of spinel at the interface are discussed. Fine spinel crystals were also found within the matrix and adjacent to the interface. They likely form by oxidation of the aluminum melt during processing.

• OSTI ID: 143657
• Report Number(s): CONF-930246--; ISBN 0-87339-251-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ALUMINIUM OXIDES
CHEMICAL COMPOSITION
COMPOSITE MATERIALS
INTERFACES
MAGNESIUM OXIDES
MECHANICAL PROPERTIES