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Schematic diagram (lattice planes) showing an edge dislocation. Burgers vector in black, dislocation line in blue. A crystalline material consists of a regular array of atoms, arranged into lattice planes. An edge dislocation is a defect where an extra half-plane of atoms is introduced midway through the crystal, distorting nearby planes of atoms.
The edge dislocation can be imagined as the introduction of a half plane (gray boxes) that does not fit the crystal symmetry. The screw dislocation can be imagined as cut and shear operation along a half plane. The vector's magnitude and direction is best understood when the dislocation-bearing crystal structure is first visualized without the ...
The dislocation line is presented in blue, the Burgers vector b in black. Edge dislocations are caused by the termination of a plane of atoms in the middle of a crystal. In such a case, the adjacent planes are not straight, but instead bend around the edge of the terminating plane so that the crystal structure is perfectly ordered on either side.
Glissile dislocations contribute to slip and hardening, but sessile dislocations contribute only to latent hardening. [5] Diffraction methods cannot generally resolve the slip plane of a residual dislocation. For example, in Zr, the screw components of 𝑎 dislocations could slip on prismatic, basal, or 1st-order pyramidal planes.
Two types of dislocations exist: edge and screw dislocations. Edge dislocations form the edge of an extra layer of atoms inside the crystal lattice. Screw dislocations form a line along which the crystal lattice jumps one lattice point. In both cases the dislocation line forms a linear defect through the crystal lattice, but the crystal can ...
An edge dislocation produces a stress field which is compressive above the slip plane and tensile below. [6] In Al-Mg alloys, the Mg atom is larger than an Al atom and has lower energy on the tension side of the dislocation slip plane; therefore, Mg atoms in the vicinity of an edge dislocation are driven to diffuse across the slip plane (see ...
Figure 1: The names for the various atomic positions in the TLK model. This graphic representation is for a simple cubic lattice. Figure 2: A scanning tunneling microscope image of a clean silicon (100) surface showing a step edge as well as many surface vacancies. Many kink sites are visible along the terrace edge.
For example, an edge dislocation may split into two Shockley partial dislocations with burger’s vector of 1/6<112>. [4] This direction is no longer in the closest packed direction, and because the two burger’s vectors are at 60 degrees with respect to each other in order to complete a perfect dislocation, the two partial dislocations repel ...