dislokation

Dislokation, commonly referred to in English as dislocation, is a line defect in a crystalline lattice that represents a disruption of the regular arrangement of atoms. It is central to the plastic deformation of most crystalline solids. In some languages, including German, the term Dislokation is used to denote the same concept; in English, dislocation is the preferred term.

There are two primary types: edge dislocations, where an extra half-plane of atoms terminates within the crystal, and screw dislocations, where the lattice planes spiral around the dislocation line. Mixed dislocations exhibit characteristics of both. Each dislocation is described by a Burgers vector, which quantifies the lattice distortion around the defect and is determined by the closure failure of a loop encircling the dislocation line.

Dislocations move under applied stress. Glide occurs along specific slip planes and directions, enabling plastic shear at relatively low stresses. At higher temperatures, dislocations can also climb by atomic diffusion, allowing motion out of the slip plane. The mobility and interactions of dislocations govern a material’s yield strength and work-hardening behavior.

Dislocations form during crystal growth, phase transformations, and especially during plastic deformation. They can multiply via mechanisms such as the Frank–Read source and form complex networks through interactions. Obstacles like solute atoms, precipitates, or grain boundaries hinder dislocation motion and increase strength.

Characterization methods include transmission electron microscopy and diffraction techniques. In materials engineering, strategies to tailor mechanical properties focus on controlling dislocation behavior through alloying, grain size refinement, and precipitation hardening.