Analytical and numerical determination of the elastic interaction energy between glissile dislocations and stacking fault tetrahedra in FCC metals

Understanding flow localization in materials containing high concentrations of Stacking Fault Tetrahedra (SFT’s) depends on delineation of the mechanisms by which they are destroyed as effective dislocation obstacles. The elastic interaction between glissile dislocations and SFT’s in FCC metals is examined, both analytically and numerically. Numerical calculations are performed for both full and truncated tetrahedra interacting with edge dislocations, while a new analytical formula is derived for the elastic energy of a full tetrahedron-dislocation system. Calculations confirm that the stress field of glissile dislocations is not sufficient to re-configure SFT’s into faulted Frank loops by reverse glide of stair-rod dislocations. This mechanism of SFT destruction by shear unfaulting of Frank loops seems to be unlikely. It is proposed that the destruction of SFT’s in irradiated materials is enabled by dislocation drag of interstitial clusters, followed by subsequent recombination and melting of the SFT core.