Fig. 7

Critical dislocation breakaway events in an L = 20 nm sample loaded in both forward (left column) and reverse shear loading (right column). The leading partial dislocations are always the first to overcome the platelet obstacles, with (a) platelet B overcome first during forward shear loading and (b) platelet A overcome first during reverse shear loading. The trailing partial dislocations always follow and require higher applied shear stresses, with (c) platelet A overcome last during forward shear loading and (d) platelet B overcome last during reverse shear loading. All of the FCC atoms have been removed for clarity