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# Slip (materials science)

Slip is the process by which plastic deformation is produced by a dislocation motion. By an external force, parts of the crystal lattice glide along each other, resulting in a changed geometry of the material. Depending on the type of lattice, different slip systems are present in the material. More specifically, slip occurs between planes containing the smallest burgers vector. The picture on the right shows a schematic view on the slip mechanism.

## FCC

Slip in FCC crystals occurs along the close packed plane. Specifically, the slip plane is of type {111}, and the direction is of type <110>. In the diagram, the specific plane and direction are (111) and [-110], respectively. Given the permuations of the slip plane types and direction types, FCC crystals have 12 slip systems. In the FCC lattice, the burgers vector, b, can be calculated using the following equation:[1]

$|b|= \frac {a}{2}= \frac{a}{\sqrt 2}$[1]

Where a is the lattice constant of the unit cell.

## BCC

Slip in BCC crystals occurs along the plane of shortest burgers vector as well. In the BCC crystal the slip plane is of type {110}, and the direction is of type <111>. In the diagram the specific slip plane and direction are (110) and [-111], respectively.[1]