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FIBER-REINFORCED METALS AND ALLOYS
IIT RESEARCH INST CHICAGO ILL
A fundamental investigation into the deformation mechanism of composite materials by microstraining and slip line observations showed that plastic deformation starts in the weaker matrixAND THAT FIBERS STRENGTHEN THE COMPOSITES BY DECREASING THE AVAILABLE SLIP LENGTH IN THE MATRIX. Hence, the main effect of fibers is to increase the rate of work hardening which leads to a higher yield stress. The mechanical properties of several different composites made from fibers of 0.0002 to 0.001 in. in diameter were investigated. Best results were obtained with an aluminum matrix strengthened with 1-mil diameter tungsten fibers the yield strength nearly tripled with the addition of only 12 volume 50 weight per cent fibers. Youngs modulus also increased with the amount of fibers added. Another attractive set of composites was found with a silver matrix reinforced with type 430 stainless steel fibers, 1 mil in diameter. Attempts were made to reinforce an aluminum, an Al-4 Cu alloy, and a 50 Cu-50 Ni alloy matrix with 0.0002 in. diameter graphite fibers, but the graphite was found to be a relatively poor reinforcing material. Author