There are benefits to compositing two or more materials. Composite materials take advantage of the unique properties of each component and are designed to optimize the strength, density, electrical properties, and cost of the materials.

Many conventional materials such as plywood, reinforced rubber, and reinforced concrete are composites since they consist of combinations of materials. Concrete, with its cement matrix and rock aggregate, is a composite. To many, however, the term composite material refers to a specific category of advanced composites.

Advanced composites have emerged primarily as a result of the aircraft and spacecraft industries, in which there are extremes in strength and weight requirements. New metals have been created that not only meet this demand, but also are capable of resisting fatigue, corrosion, and vibration.

Fiber-reinforced metal-matrix composites (MMCs) consist of high-performance metallic reinforcements--glass, boron or graphite filaments--in matrices of aluminum, titanium, magnesium, copper, or...