Materials Science and Engineering

Materials science and engineering studies the structure of materials, the properties that arise from that structure, and how materials are processed and selected for use. It links chemistry, physics and engineering, asking why a metal bends while a ceramic shatters, and how a material's internal arrangement of atoms governs its strength, stiffness and behaviour under load. Engineers draw on this knowledge to choose the right material for a component and to develop new materials with improved performance.

Engineering materials are commonly grouped into broad classes. Metals, such as steel, aluminium alloys, copper and tin, are typically strong, ductile and good conductors of heat and electricity, and many can be alloyed to tune their properties. Polymers, including plastics, are built from long chains of molecules and tend to be lightweight, flexible and electrically insulating. Ceramics are hard, heat-resistant and brittle, while composites combine two or more materials to gain properties that none possesses alone, such as the strength of fibres bound in a lightweight matrix.

The mechanical behaviour of a material is described by properties such as strength, the stress it can bear before failing; stiffness, its resistance to elastic deformation; and ductility, its ability to stretch without breaking. When a load is applied, a material deforms, and the relative change in its dimensions is called strain. By relating these properties to internal structure, materials engineers can predict performance and avoid failure in service.

Frequently asked questions

What are the main classes of engineering materials?

They are usually grouped as metals, polymers, ceramics and composites, with each class sharing characteristic patterns of strength, stiffness, weight and behaviour under heat and load.

What is an alloy?

An alloy is a metal made by combining a base metal with one or more other elements, such as steel from iron and carbon, in order to improve strength, hardness, corrosion resistance or other properties.

What is the difference between stress and strain?

Stress is the internal force per unit area within a loaded material, while strain is the resulting relative deformation, such as the fractional change in length.