materials science

Strength in a material is its ability to withstand force without breaking. The different types of strength of individual materials make them suited to different tasks. In any design and technology project the engineer or designer will select the materials with the optimum strength profile.

In engineering, the study of the microstructure of materials and of how it relates to their properties and behaviour. The materials concerned are metals, semiconductors, ceramics, polymers (plastics), and composites (made of more than one type of material). Materials scientists test how these respond to the application of stresses, electrical currents, magnetic fields, high or low temperatures, corrosion, or bacterial degradation. They also design new materials, tailored to meet specific requirements, and in recent years have developed superconductors, aerogels, aramid and carbon fibres, and smart materials that contain sensors and switches to improve their own performance.

Increasingly, materials scientists also study natural materials, such as bone, wood, and feathers, to see how their properties can be transferred to synthetic materials.

Properties of materials It is important to know the properties of materials when designing and manufacturing products, in order to understand how the material will look and behave. Chemical properties include how the material is affected by water, acids, bases, combustion, or oxidizing and reducing agents. Physical properties include brittleness (whether the material breaks when hammered), malleability (whether the material may be hammered or rolled into a different shape), ductility (whether the material may be drawn into wires), elasticity (whether the material will return to its original shape and size after being stretched, bent, or twisted), and flexibility (whether the material will bend when a force is applied). Materials can be grouped according to their properties into types such as metals, plastics, and timber.

Forces on materials Forces cause materials to change. A force may make a material change shape, or it may cause it to fail (for example by buckling, tearing, snapping, breaking, cracking, or splintering). Tensile forces cause a material to stretch, or to break if the stresses created inside the material become too great. Torque (twisting) forces cause a material to shear, or to rip or tear. Compression forces cause a material to compact.