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Thermal degradation of the tensile strength of unidirectional boron/aluminum compositesThe variation of ultimate tensile strength with thermal treatment of B-Al composite materials and of boron fibers chemically removed from these composites is studied systematically in an attempt to determine the mechanism of the resulting strength degradation. The results indicate that thermally cycling of B-Al represents a more severe condition than equivalent time at temperature. Degradation of composite tensile strength from about 1.3 GN/sq m to as low as 0.34 GN/sq m was observed after 3000 cycles to 420 C for 203-micron B-1100 Al composite. In general, the 1100 Al-matrix composites degraded somewhat more than the 6061 matrix material studied. Measurement of fiber strengths confirmed a composite strength loss due to the degradation of fiber strength. Microscopy indicated a highly flawed fiber surface. On the basis of various thermal-cycling studies and electron diffraction analysis, a mechanism is favored in which B reacts with Al, freshly exposed by cold working during cycling, to form AlB2. The nonuniform interface reaction leads to a highly flawed and weakened B fiber.
Document ID
19770065113
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Grimes, H. H.
(NASA Lewis Research Center Cleveland, OH, United States)
Lad, R. A.
(NASA Lewis Research Center Cleveland, OH, United States)
Maisel, J. E.
(NASA Lewis Research Center Cleveland, Ohio, United States)
Date Acquired
August 9, 2013
Publication Date
March 1, 1977
Subject Category
Composite Materials
Meeting Information
Meeting: Spring Meeting of the American Institute of Mining, Metallurgical and Petroleum Engineers,
Location: Atlanta, GA
Start Date: March 6, 1977
End Date: March 11, 1977
Sponsors: American Institute of Mining, Metallurgical and Petroleum Engineers
Accession Number
77A47965
Distribution Limits
Public
Copyright
Other

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