Defect Interactions Between Screw Dislocations and Coherent Twin Boundaries in Several Fcc Materials

The atomistic interactions between screw dislocations and coherent twin boundaries were investigated in face-centered metals of Al, Cu, Ni, Au, Ag, and Pd using molecular dynamics and nudged elastic band method. The interaction mechanism was affected by stable and unstable stacking fault energies predicted by various potentials. In Al, Cu, and Pd, screw dislocation would be absorbed by the twin boundary. However. transmissions were observed in Ni, Au, Ag, and Pd with another potential. It was found that both the critical interaction stress and energy barrier decreased as the reciprocal of the difference between unstable and stable stacking fault energies increased. Activation volumes and strain rate sensitivities were estimated around 14 b(3) to 27 b(3), where b is the Burgers vector, and 0.011 to 0.023, respectively. The results for Cu and Ni were further compared with experiments and showed good agreements.