ABSTRACT
The mechanical and corrosion properties of metals and alloys that lead to their successful engineering application are due to microstructural details that, in the majority of cases, depend on phase transformations occurring during solid state processing of the material. These can be classified as diffusional and diffusionless transformations. Diffusional transformations can involve both short-range and long-range diffusion depending on whether the transformation involves a change in chemical composition. Although the emphasis of the chapter is on precipitation and eutectoid transformations, the essentials of massive and ordering transformations are also described. A treatment of the factors affecting nucleation and growth rates, overall transformation kinetics and precipitate morphology are given for both metastable and equilibrium phases in steels and precipitation hardening aluminum alloys. The eutectoid transformations of austenite to pearlite and bainite are covered in some detail. The principles involved are illustrated with case studies from titanium alloys, aluminum–copper–lithium alloys and nanostructured bainite.
