A vacancy is produced when an atom or an ion is missing from its normal site in the crystal structure.

Interstitial defect Formed when an extra atom or ion is inserted into the crystal structure at a normally unoccupied position.

Substitutional defect Introduced when one atom or ion is replaced by a different type of atom or ion.

Plastic deformation Refers to irreversible deformation or change in shape that occurs when the force or stress that caused it is removed

Elastic deformation Temporary change in shape that occurs while a force or stress remains applied to a material

Dislocation density Represents the amount of dislocations present

Metallography Process of preparing a metallic sample and observing or recording its microstructure is called metallography

Effect on mechanical properties via control of the slip process Defects in materials, such as dislocations, point defects, and grain boundaries, serve as stop signs for dislocations. Strain Hardening: Mechanism of increasing the strength of a material by deformation

Solid-solution strengthening Intentionally introducing substitutional or interstitial atoms. Effects on electrical, optical, and magnetic properties Dislocations and other defects can interfere with motion of charge carriers. Dislocation densities in optical and electrical applications should be very small.