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Unformatted text preview: than a polycrystalline specimen of a metal. d) Why are higher yield strength metal alloys usually more brittle than lower yield strength alloys? e) Why do carbon fibers or glass-fibers have such high strengths compared to the bulk materials (graphite and glass)? f) Explain this observation. The first aerospace aluminum alloy (Duralumin) was found to have a hardness that depends on the length of time that it is exposed to an elevated temperature. Initially the hardness increases with exposure time until it reaches a maximum value, after which the hardness decreases with additional elevated temperature exposure....
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- Fall '05