Recoverable plasticity in penta-twinned metallic nanowires (INVITED)

Abstract eng:
There has been relatively little study on time-dependent mechanical properties of nanowires, in spite of their utmost importance for the design, fabrication and operation of nanoscale devices. Here we report a dislocation-mediated, fully recoverable, plastic behavior in penta-twinned silver nanowires. In—situ tensile experiments inside scanning and transmission electron microscopes show that penta—twinned silver nanowires undergo stress relaxation upon loading and complete plastic strain recovery upon unloading, while the same experiments on single-crystalline silver nanowires do not exhibit such a behaviour. Molecular dynamics simulations reveal that the observed behaviour in penta-twinned nanowires originates from the surface nucleation, propagation and retraction of partial dislocations. More specifically, vacancies reduce dislocation nucleation barrier, facilitating stress relaxation, while the twin boundaries and their intrinsic stress field promote retraction of partial dislocations, resulting in full strain recovery.

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