Polycrystalline Solids
• A Polycrystalline Solid is made up of an aggregate of many small single crystals
(crystallites or grains). Polycrystalline materials have a high degree of order over
many atomic or molecular dimensions have a high degree of order over
• These ordered regions, or single crystal regions, vary in size & orientation with
' w respect to one another. These regions are called grains (or domains) & are separated from one another by. grain boundaries.
The atomic order can vary from one domain to the next. The grains are usually
100 nm ~ 100 microns in diameter.
• Polycrystals with grains that are < 10 nm in diameter are calle