Alloys and Compounds

Pure materials have a number of inherent mechanical properties, as discussed in Chapter 3. These features, such as strength or ductility, can be altered only to a limited degree, for example, by work hardening. In contrast to this, the properties of materials can be varied significantly if one combines several elements, that is, by alloying. In this chapter, we shall unfold the multiplicity of the mechanical properties of alloys and compounds with particular emphasis on the mechanisms which are involved. Specifically, we shall discuss a number of techniques which increase the strength of materials. Among them are solid solution strengthening, precipitation hardening (age hardening), dispersion strengthening, and grain size strengthening. In order to understand these mechanisms, we need to study the fundamentals of phase diagrams.