A comprehensive dislocation dynamics study was made of the resistance of stacking fault tetrahedra to screw dislocation glide. The methodology explicitly accounted for partial dislocation reactions in face-centered cubic crystals, which permitted the obtention of more detailed insights into the dislocation/stacking-fault-tetrahedron interaction than had previous dislocation dynamics studies. The resistance arising from stacking fault surfaces, to dislocation-cutting, was computed by using atomistic simulations and was added, in the form of a point stress, to the dislocation dynamics methodology. A value of 1658.9MPa was obtained for Cu; which translated into an extra force, resolved on the glide plane, which dislocations had to overcome before they could penetrate stacking fault tetrahedra. In fact, it was found they did not do so; leading to two well-differentiated regimes: one in which partial dislocation reactions resulted in partial stacking fault tetrahedron damage, and one in which impenetrable stacking fault tetrahedra resulted in the creation of Orowan loops. Stacking-fault-tetrahedron strength maps were obtained as a function of dislocation-glide-plane/SFT-intersection-height interaction orientation and dislocation line-length. In general, the stacking fault tetrahedra were weaker obstacles the smaller the triangular area which was encountered. This permitted the derivation of simple scaling laws having the slipped area as the only variable. These laws sufficed to explain all strength curves and were used to derive a simple model of dislocation/SFT strength. The stresses required to break through obstacles in the 2.5 to 4.8nm size range were computed to be 100 to 300MPa; in good agreement with some experimental estimations and molecular dynamics calculations.

A Dislocation Dynamics Study of the Strength of Stacking Fault Tetrahedra. Part I: Interactions with Screw Dislocations. E.Martinez, J.Marian, A.Arsenlis, M.Victoria, J.M.Perlado: Philosophical Magazine, 2008, 88[6], 809-40