Crystallite

Polycrystalline materials, or polycrystals, are solids that are composed of many crystallites of varying size and orientation.

Most materials are polycrystalline, made of a large number crystallites held together by thin layers of amorphous solid.

Most inorganic solids are polycrystalline, including all common metals, many ceramics, rocks, and ice.

If the individual crystallites are oriented completely at random, a large enough volume of polycrystalline material will be approximately isotropic.

This property helps the simplifying assumptions of continuum mechanics to apply to real-world solids.

However, most manufactured materials have some alignment to their crystallites, resulting in texture that must be taken into account for accurate predictions of their behavior and characteristics.

If a rock forms very quickly, such as from the solidification of lava ejected from a volcano, there may be no crystals at all.

The high interfacial energy and relatively weak bonding in grain boundaries makes them preferred sites for the onset of corrosion and for the precipitation of new phases from the solid.

In nanocrystalline solids, grain boundaries become a significant volume fraction of the material, with profound effects on such properties as diffusion and plasticity.

In the limit of small crystallites, as the volume fraction of grain boundaries approaches 100%, the material ceases to have any crystalline character, and thus becomes an amorphous solid.

The inductive head measures the orientation of the magnetic moments of these domain regions and reads out either a “1” or “0”.

Grain size is important in this technology because it limits the number of bits that can fit on one hard disk.

The result was directional solidification processing in which grain boundaries were eliminated by producing columnar grain structures aligned parallel to the axis of the blade, since this is usually the direction of maximum tensile stress felt by a blade during its rotation in an airplane.