Stacking-fault Energy

The stacking-fault energy (SFE) is a material property on a very small scale. It is noted as γ_SFE in units of joules per square metre.

A stacking fault is a one or two layer interruption in the stacking sequence of the crystal structure. These interruptions carry a certain stacking fault energy. The width of stacking fault is a consequence of the balance between the repulsive force between two partial dislocations on one hand and the attractive force due to the surface tension of the stacking fault on the other hand. The equilibrium width is determined by the stacking fault energy. When the SFE is high, the dissociation of a perfect dislocation into two partial is unlikely and the material deforms only by dislocation glide. Lower SFE materials display wider stacking faults and have more difficulties for cross-slip and climb. The SFE modifies the ability of a dislocation in a crystal to glide onto an intersecting slip plane. When the SFE is low, the mobility of dislocations in a material decreases.