PPT Slide
Crystalline solids (most materials) generally consist of millions of individual grains separated by boundaries.
Each grain (or subgrain) is a single crystal.
Within each individual grain there is a systematic packing of atoms. Therefore each grain has different orientation (see Figure 16-1) and is separated from the neighboring grain by grain boundary.
When the misorientation between two grains is small, the grain boundary can be described by a relatively simple configuration of dislocations (e.g., an edge dislocation wall) and is, fittingly, called a low-angle boundary.