Relationship of fatigue and fracture to microstructure and processing in Al/sub 2/O/sub 3/ fiber reinforced metal matrix composites
The tensile and fatigue properties of three matrices, including commercially pure magnesium, ZE41A (Mg-4.25Zn-0.5Zr-1.25RE), and Al/sub 3/Li, containing 35 vol pct FP Al/sub 2/O/sub 3/ fibers were studied as a function of orientation between the loading and fiber axes, matrix composition, fiber volume fraction, and fiber/matrix interfacial chemistry. It was found that the axial properties were controlled by the fiber strength, and the orientation dependence of tensile strength could be analyzed in terms of the critical strains to fracture parallel and normal to the fibers. Matrix chemistry modifications had little influence on fiber strength but significantly increased the matrix and interface strengths. A transition from fiber-controlled fracture to matrix/interface controlled fracture was found as the 90 deg. As the matrix and interface strengths increased, a transition in fatigue properties were primarily controlled by the matrix and/or interface strengths. Little benefit was achieved by increasing the vol pct fibers from 35 to 55, unless the fibers were involved in the fracture process. The interfacial reaction zone was identified as MgO int he Mg-base composites and LiAl/sub 5/O/sub 8/ in the Al/sub 3/Li composite.
- Research Organization:
- Southwest Research Inst., San Antonio, TX (USA). Dept. of Materials Sciences
- OSTI ID:
- 5897870
- Report Number(s):
- AD-A-163859/2/XAB
- Country of Publication:
- United States
- Language:
- English
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Cermets
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ALKALINE EARTH METALS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COMPOSITE MATERIALS
CONTROL
CRYSTAL STRUCTURE
ELEMENTS
FATIGUE
FIBERS
FRACTURE PROPERTIES
INTERFACES
MAGNESIUM
MATERIALS
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METALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
TENSILE PROPERTIES