Improvement of thermal and mechanical properties of graphite/copper composites through interfacial modification |
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Authors: | S M DeVincent G M Michal |
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Affiliation: | (1) Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio |
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Abstract: | Unidirectionally reinforced graphite/copper composites have been fabricated using a pressure infiltration casting procedure.
T300 and T650 graphite fibers have been used to reinforce copper and copperchromium alloys. The effects of the chromium level
in the copper matrix on the tensile strength, stiffness, and thermal expansion behavior of the composites have been evaluated
through tensile and three-point bend testing, and thermal cycling. At the 0.5 wt% alloying level, chromium increases the stiffness
and optimizes the thermal expansion behavior of graphite/copper composites. The longitudinal tensile strengths of these composites
are above 1606 MPa, whereas the transverse tensile strengths are lower than 40 MPa due to incomplete infiltration during processing.
Scanning electron microscopy analyses reveal that the unalloyed copper matrix composites experienced extensive fiber/matrix
debonding under tensile loading. The addition of chromium to the copper increases the level of matrix bonding to the graphite
fibers, as evidenced by observations of fractured tensile specimens. Auger electron spectroscopy analyses indicate that a
chromium carbide phase present at the interface is responsible for the improved bonding. |
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Keywords: | composites copper graphite fibers metal matrix |
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