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Titanium Metal Matrix Composites
There are very few titanium-based MMCs in current production, with only two basic types
of matrices. One, intermetallic-matrix composite (IMC), uses continuous fiber. The other
is formed from titanium carbide particulates. Both have been developed primarily for
high-temperature applications, as in engine components and skins for military aircraft.
IMCs are formed from a series of titanium-aluminide foils consolidated with boron-coated
silicon carbide continuous fibers. With a starting price of $2000-3000 per pound, it is
unlikely they will soon find applications in the bicycle field. Interestingly, raw ingots
of titanium cost only $10-12 per pound, so the processing costs to create IMCs are obviously
formidable.
Titanium carbide MMCs present similar cost issues. They also suffer from a severe loss of
ductility which arises from the induction of carbon into titanium.
Titanium-aluminides are another newly publicized group of aerospace alloys. Strictly
speaking, these are not MMCs, but they do boast very high strength and good resistance
to loss of mechanical properties at high temperatures. However, they suffer from abysmal
ductility at room temperature and exorbitant cost. The ductility issue may soon be resolved;
cost, however is unlikely to drop within the foreseeable future.
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