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What are Materials?

What do we mean by "materials"? The simplest definition is simply "stuff" - indeed Ivan Amato has written a whole book with this title, and it is very easy to read. There is natural stuff - wood, bone, straw, wool, cotton - and there is man-made stuff - steel, pottery, plastic, semiconductors, concrete, textiles, paper. People interested in materials are usually fascinated by two questions: "Why does each material behave the way it does?" and "How can I exploit the properties of a material to make something better or cheaper?"

The people who concentrate on the "Why?" question are Materials Scientists, and those who focus on the "How?" question are Materials Engineers. Both types of Materials specialists need to know what properties each material has and how they might be changed. Only very rarely can the answers be deduced using our bare hands and the naked eye, so the study of materials inevitably involves testing materials (that is, measuring their properties) and looking at their microstructure (using a microscope). The more theoretical side of the discipline is then to deduce how the properties (strength, transparency, flexibility, conductivity and so on) are related to the structure (crystal size, alignment of fibres, etc.). The challenge is then to use this knowledge to design and make materials which have better properties for our purpose.

Examples of this approach include the development of alloys which can be used at higher and higher temperatures in turbine engines and the development of plastics so resistant to breaking when bent that they can be used as hinges. Neither Engineers nor Materials specialists could do these things fifty years ago, yet today they are commonplace.

Professor Peter Goodhew Director, UK Centre for Materials Education