Elevated-Temperature-Delayed Failure of Alumina Reinforced with 20 vol% Silicon Carbide Whiskers |
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Authors: | Paul F. Becher Peter Angelini W. H. Warwick Terry N. Tiegs |
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Affiliation: | Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 |
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Abstract: | Alumina composites reinforced with 20 vol% SiC whiskers were exposed to applied stresses in four-point flexure at temperatures of 1000°, 1100°, and 1200°C in air for periods of up to 14 weeks. At 1000° and 1100°C, an "apparent" fatigue limit was established at stresses of ∼ 75% of the fast fracture strength. However, after long-term (>6 weeks) tests at 1100°C, some evidence of crack generation as a result of creep cavitation was detected. At 1200°C applied stresses as low as 38% of the 1200°C fracture strength were sufficient to promote creep deformation and accompanying cavitation and crack generation and growth resulting in failures in times of <250 h. |
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Keywords: | alumina silicon carbide composites mechanical properties whiskers |
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