Materials science and engineering

Materials science and engineering

A multidisciplinary field concerned with the generation and application of knowledge relating to the composition, structure, and processing of materials to their properties and uses. The field encompasses the complete knowledge spectrum for materials ranging from the basic end (materials science) to the applied end (materials engineering). It forms a bridge of knowledge from the basic sciences (and mathematics) to various engineering disciplines.

The study of metallic materials constitutes a major division of the materials science and engineering field. Most metals have a crystalline structure of closely packed atoms arranged in an orderly manner. In general they are good electrical and thermal conductors. Many are relatively strong at room temperature and retain good strength at elevated temperatures. Metals and alloys are often cast into the nearly final shape in which they will be used (castings). Ferrous metals and alloys contain iron as their major metallic element; nonferrous metals and alloys contain elements other than iron as their major metallic element. See Alloy, Metal, Metal casting

The study of ceramic materials forms a second major division of the field of materials science and engineering. Ceramics are inorganic materials consisting of metallic and nonmetallic elements chemically bonded together. Most ceramic materials have high hardness, high-temperature strength, and good chemical resistance; however, they tend to be brittle. Ceramics in general have low electrical and thermal conductivities, which makes them useful for electrical and thermal insulative applications. Most ceramic materials can be classified into three groups: traditional ceramics, technical ceramics, and glasses. See Ceramics, Glass

The study of polymeric materials forms a third major division of materials science and engineering. Most of these materials consist of carbon-containing long molecular chains or networks. Structurally, most of them are noncrystalline, but some are partly crystalline. The strength and ductility of polymeric materials vary greatly. Most polymers have low densities and relatively low softening or decomposition temperatures. Many are good thermal and electrical insulators. Polymeric materials have replaced metals and glasses for many applications.

A fourth major division of materials science and engineering comprises the study of composite materials. A composite material is a mixture of two or more materials that differ in form and chemical composition and are essentially insoluble in each other, and most are produced synthetically by combining various types of fibers with different matrices to increase strength, toughness, and other properties. Three important types of composite materials have polymeric, metallic, or ceramic matrices. See Composite material

In addition to metallic, ceramic, polymeric, and composite materials, materials science and engineering is also concerned with the research and development of other special classes of materials that are based on applications. Some major types of these materials are electronic materials, optical materials, magnetic materials, superconducting materials, dielectric materials, nuclear materials, biomedical materials, and building materials. See Integrated circuits, Superconducting devices