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Unit cell of an fcc material. Lattice configuration of the close packed slip plane in an fcc material. The arrow represents the Burgers vector in this dislocation glide system. Slip in face centered cubic (fcc) crystals occurs along the close packed plane. Specifically, the slip plane is of type , and the direction is of type < 1 10>.
In crystalline metals, slip occurs in specific directions on crystallographic planes, and each combination of slip direction and slip plane will have its own Schmid factor. As an example, for a face-centered cubic (FCC) system the primary slip plane is {111} and primary slip directions exist within the <110> permutation families.
The possible cross-slip planes are determined by the crystal system. In body centered cubic (BCC) metals, a screw dislocation with b=0.5< 1 11> can glide on {110} planes or {211} planes. In face centered cubic (FCC) metals, screw dislocations can cross-slip from one {111} type plane to another.
The primitive and cubic close-packed (also known as face-centered cubic) unit cells. In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals . There are three main varieties of these crystals:
Stacking-fault energy. The stacking-fault energy (SFE) is a materials property on a very small scale. It is noted as γ SFE in units of energy per area. A stacking fault is an interruption of the normal stacking sequence of atomic planes in a close-packed crystal structure. These interruptions carry a certain stacking-fault energy.
Partial dislocation. In materials science, a partial dislocation is a decomposed form of dislocation that occurs within a crystalline material. An extended dislocation is a dislocation that has dissociated into a pair of partial dislocations. The vector sum of the Burgers vectors of the partial dislocations is the Burgers vector of the extended ...
Crystal twinning. Quartz – Japan twin. Diagram of twinned crystals of albite. On the more perfect cleavage, which is parallel to the basal plane (P), is a system of fine striations, parallel to the second cleavage (M). Crystal twinning occurs when two or more adjacent crystals of the same mineral are oriented so that they share some of the ...
In geometry, close-packing of equal spheres is a dense arrangement of congruent spheres in an infinite, regular arrangement (or lattice ). Carl Friedrich Gauss proved that the highest average density – that is, the greatest fraction of space occupied by spheres – that can be achieved by a lattice packing is. .