On the energy of terminated stacking faults

The equilibrium of dissociated dislocations is discussed in terms of intrinsic material properties such as the ideal stacking fault energy (ideal SFE) and the stacking fault (SF) strain. The ideal SFE is de® ned as the energy per unit area of an in® nitely extendedSF in an ideal in® nite crystal. The e€ ective SFE is de® ned as the energy per unit area of a terminated SF. The terminated SF is associated with a strain ® eld. The strain ® eld is modelled in terms of conventional and Somigliana dislocations. It is found that the e€ ective SFE signi® cantly overestimates the ideal SFE if the ideal SFE is low and the SF strain is large. A numerical example is given for austenitic stainless steel.