Chapter 10 - The Growth and Stability of Cellular Microstructures

Abstract

This chapter demonstrates that there are clear relationships among various annealing phenomena, and that they can be analyzed within a unified framework. Such an approach is particularly useful when annealing behavior that does not easily fit within the conventional definitions has to be analyzed. This chapter examines why some microstructural changes occur uniformly or continuously throughout the microstructure, whereas others occur discontinuously. If a material does not contain many free dislocations, so that the microstructure can be described in terms of subgrains and grains, we can characterize it in terms of an assembly of cells. Thus, a subgrain in a deformed and recovered material differs from a grain in a fully recrystallized material only by the size of the cells and the misorientation between them. Annealing of these microstructures occurs by the migration of high or low angle boundaries. Uniform coarsening of such cellular microstructures leads to continuous processes such as subgrain coarsening and normal grain growth, whereas inhomogeneous growth results in discontinuous processes such as recrystallization and abnormal grain growth.