slipsystem

Slip system refers to a specific combination of a crystallographic plane and a crystallographic direction along which dislocations move during plastic deformation. A crystal can deform plastically when dislocations glide along active slip systems under applied stress. The likelihood that a given system will conduct plastic flow depends on the resolved shear stress on that system, which is determined by the orientation of the applied load relative to the slip plane and slip direction (often described by the Schmid factor).

Materials with numerous close-packed slip systems tend to be more ductile because many dislocation glide paths are available, whereas materials with few slip systems are less ductile and more anisotropic.

Common examples: In face-centered cubic (FCC) metals such as aluminum and copper, the primary slip systems are the {111} planes with <110> directions, giving 12 equivalent systems and high ductility. In hexagonal close-packed (HCP) metals such as magnesium, slip is typically limited to the basal {0001} plane with <11-20> directions at room temperature; other systems may activate with higher temperatures or alloying. In body-centered cubic (BCC) metals such as iron, slip systems are numerous and depend strongly on temperature; families such as {110}<111>, {112}<111>, and {123}<111> can contribute to plastic flow under appropriate conditions.

Understanding slip systems helps explain material strength, ductility, and formability and underpins processes such as forging, extrusion, and cold or warm working. Designers tailor slip behavior through alloying, heat treatment, and deformation conditions to achieve desired mechanical properties.