SFE: Stacking Fault Energy
Definition:The energy stored in stacking faults (→SFs).
Explanation:A SF is a one or two layer interruption in the stacking sequence of the crystal structure. These interruptions carry certain SFE. The width of a SF is a consequence of the balance between the repulsive force between two partial dislocations on one the hand and the attractive force due to the surface tension of the SF on the other hand. The equilibrium width is determined by the SFE. 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 SFs and have more difficulties for cross slip and climb. In other words, the SFE controls the ability of a dislocation in a crystal to glide onto an intersecting slip plane by determining the degree of dislocation extension, which consequently affects the mobility of dislocations for the cross slip. When the SFE is low, the mobility of dislocations in a material decreases. Therefore, information about the amount of splitting and of the SFE can be obtained by measuring dislocation mobilities [1].
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Fig. 1. SFE of the three twinning induced plasticity (TWIP) steel alloys as a function of temperature [2].
SFB-Link:SFE influences the deformation mechanisms of the high Mn steels.
References:[1] M.Ahlers. Stacking fault energy and mechanical properties[J]. Metallurgical and materials transactions B, 1970, 1: 2415-2339.
[2] S.Curtze, V.-T.Koukkala. Effects of temperature and strain rate on the tensile properties of twip steels[J]. Revista Materia, 2010, 15: 157-163.