Beryllium carbide fiber

As noted above, the range of fibers employed does not precisely overlap with those employed for organic composites. Because the formation of the MMCs generally requires melting of the metal-matrix, the fibers need to have some stability to relatively high temperatures. Such fibers include graphite, silicon carbide, boron, alumina-silica, and alumina fibers. Most of these are available as continuous and discontinuous fibers. It also includes a number of thin metal wires made from tungsten, titanium, molybdenum, and beryllium. 

Nylon, polyester (unsaturated) and, currently, aromatic Nylons (aramides) like Kevlar. High-performance (and expensive) reinforcing fillers include carbon (mainly graphite) fibers, alumina, silicon, carbide, nitrite, boron, beryllium and other metals. Producing extremely high strength and stiffness, these specific fibers have been developed for space, aviation and military use. 

MMCs are usually reinforced by either monofilaments, discontinuous fibers, whiskers, particulates, or wires. With the exception of wires, which are metals, reinforcements are generally made of advanced ceramics such as boron, carbon, alumina and silicon carbide. The metal wires used are made of tungsten, beryllium, titanium, and molybdenum. Currently, the most important wire reinforcements are tungsten wire in superalloys and superconducting materials incorporating niobium-titanium and niobium-tin in a copper matrix. The most important MMC systems are presented in Table 18.5. 

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