ABSTRACT
The concept of reinforcing a material by the use of a fiber is not a new one. The Egyptian brick layer employed the same principle more than three thousand years ago when straw was incorporated into the bricks. More recent examples of fiber-reinforced composites are steel-reinforced concrete, nylon and rayon cord-reinforced tires, and fiberglass-reinforced plastics. The paucity of mechanical data, difficulties in fabrication, high costs, and degradation reactions at anticipated use temperatures have all contributed to the cautious development of reinforced metals. For high temperatures, where oxidation presents a major problem in the development of ductile structural materials, stable reinforcements such as continuous alumina filaments have considerable potential. In homogeneous materials, mechanical properties and environmental stability may have to be compromised to produce a useful structure. In filamentary reinforced metals the shear strength requirements of the matrix are nominal since the matrix serves only to transfer load into the filaments.
