The influence of material and choice of interatomic potential on the interaction between an a/2<110>{111} screw dislocation and a Σ3{111}<110> coherent twin boundary was determined by simulating this process in a range of face-centered cubic metals modelled with a total of 10 embedded-atom method potentials. Generalized stacking fault energies were computed, showing a linear relation between the stacking fault (γS) and twin energies, as well as between the unstable stacking fault (γUS) and unstable twinning (γUT) energies. It was shown that the reaction mechanism (absorption of the dislocation into the coherent twin boundary or transmission into the twinned region) and reaction stress depend strongly on the potential used, even for a given material and were controlled by the material parameter γS/μbP (where μ was the shear modulus and bP the Shockley partial Burgers vector), rather than the sign of the ratio (γUS − γS)/(γUT − γS), as proposed recently by Jin et al. Moreover, there exists a critical reaction stress, close to 400MPa, independent of the potential, below which the dislocation was absorbed in the coherent twin boundary and above which the dislocation was transmitted into the twinned region. The simulations were considered with respect to in situ transmission electron microscopy straining experiments in Cu that highlighted the importance of thermally activated cross-slip in the interaction process and showed that transmission across a twin boundary was possible but was most probably an indirect process.

Atomic-Scale Simulation of Screw Dislocation/Coherent Twin Boundary Interaction in Al, Au, Cu and Ni. M.Chassagne, M.Legros, D.Rodney: Acta Materialia, 2011, 59[4], 1456-63