Heterogeneous dislocation nucleation in single crystal copper-antimony solid-solution alloys
RK Rajgarhia and DE Spearot and A Saxena, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 17, 055001 (2009).
Molecular dynamics (MD) simulations are employed to study the partial dislocation nucleation process in single crystal copper with varying concentrations of antimony (0.0-2.0 at% Sb) under uniaxial tension. A well-established embedded-atom method potential is used to represent the Cu-Cu interactions and a recently developed Lennard-Jones potential is used for the Cu-Sb and Sb-Sb interactions. Antimony atoms are randomly distributed as substitutional defects in the Cu single crystal. MD simulations indicate that the tensile stress required for partial dislocation nucleation in the crystal decreases with increasing concentration of Sb. The strain field around Sb dopant atoms in the Cu lattice reduces the unstable stacking fault energy, which promotes heterogeneous nucleation of partial dislocations and reduces the tensile stresses required for plastic deformation. In addition, the role of Sb on the reduction in the stress required for dislocation nucleation is found to be orientation-dependent. Finally, both temperature and Sb distribution play a role in the statistical variation of the stress required for heterogeneous partial dislocation nucleation; this variation is maximum at moderate levels of Sb concentration (0.20-0.50 at% Sb).
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