1. What are grains and grain boundaries in a material? I suggest you focus on metals. Explain how material properties are affected by the size of these grains.
A grain boundary is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are defects in the crystal structure, and tend to decrease the electrical and thermal conductivity of the material. The high interfacial energy and relatively weak bonding in most grain boundaries often makes them preferred sites for the onset of corrosion and for the precipitation of new phases from the solid. They are also important to many of the mechanisms of deformation. Reducing crystal size is a great way to increase strength between molecules
2. How does one engineer or process materials to reduce the grain size? In particular, I would like for you to explore and then explain how single crystal silicon is produced for the solar industry.
Grain size is often determined by the rate at which the material cooled during forming. If you can melt the material and then cool it rapidly, that would create small grains. Using methods to first purify the substance, could use extreme amounts of heat boiling out undesired, then rapidly cool it to berid of grains.
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