Fiber reinforced aluminum matrix composite wire

A wire comprising a composite material comprising a plurality of continuous polycrystalline α-Al2O3 fibers within a matrix selected from the group consisting of an aluminum matrix and a matrix of an alloy of aluminum and up to about 2% by weight copper, based on the total weight of said alloy matrix, wherein said matrices contain less than 0.05 percent by weight impurities, based on the total weight of said matrices, wherein said plurality of continuous polycrystalline α-Al2O3 fibers includes tows of continuous polycrystalline α-Al2O3 fibers, wherein said polycrystalline α-Al2O3 fibers have an average tensile strength of at least about 2.8 GPa, wherein said continuous polycrystalline:

• α-Al2O3 fibers are free of an exterior protective coating, wherein said polycrystalline α-Al2O3 fibers comprise at least 90% by weight alumina, based on the total weight of each respective fiber, wherein at least 99% by weight of the alumina of said fibers is in the alpha phase, wherein said fibers have a uniform grain structure comprising alpha alumina crystallites having an average crystallite diameter less than 0.5 micrometer, wherein at least 95% by weight of said alpha alumina crystallites of said fibers are less than 0.5 micrometer in diameter and at least 99 percent are less than 0.7 micrometer in diameter, wherein said fibers have a density of at least 90 percent of theoretical, and wherein said wire comprises between about 30-70% by volume of said polycrystalline α-Al2O3 fibers, based on the total volume of said composite material.