Figure 4. Recoverable plasticity and associated dislocation activities.

(a) Time-dependent strain recovery due to the reverse motion of partial dislocations. (b,c) Penta-twinned NW; (b) during relaxation, dislocations are nucleated and confined by the penta-twinned nanostructure; (c) dislocations retract and disappear during recovery. (d,e) Bi-crystalline NW; (d) during relaxation, a dislocation is impeded by the TB; (e) the dislocation retracts and disappears during recovery. (f,g) Single-crystalline NW; (f) during relaxation, dislocations travel through the sample interior and escapes out of the free surface, leaving behind a permanent stacking fault; (g) after unloading, the stacking fault still resides in the sample interior, resulting in permanent plastic deformation. Only hexagonal close-packed atoms are visible in (b–g) for clarity, upper parts are viewed from NW axis and lower parts are side view of NWs. Scale bar, 5 nm.