IMPACT-INDUCED BENDING RESPONSE OF SINGLE CRYSTAL AND FIVE-FOLD TWINNED NANOWIRES
S Jiang and Z Chen and HW Zhang and YG Zheng and H Li, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, 11, 1-16 (2013).
The impact-induced bending response of single crystal and five-fold twinned copper nanowires has been investigated, based on molecular dynamics simulation with the embedded-atom method, to understand the effects of impact velocity and aspect ratio. It was found that bending vibration of the nanowires can occur with certain values of impact velocity or aspect ratio. At relatively low impact velocity and aspect ratio, only minor defects are formed in the confined impact area, and the most part of the nanowires remain in the elastic regime. The nanowires can rebound after reaching the maximum deflection, which exhibits the property of bending vibration as observed at the continuum level. By further increasing the impact velocity or aspect ratio, the vibration phenomenon becomes less obvious, and a large number of partial dislocations nucleate and slide on the 111 close-packed planes. Severe plastic deformation can occur with necking formation and ultimate breakage at very large impact velocity or aspect ratio. As compared with that of single crystal nanowires, the bending vibration of five-fold twinned nanowires shows the similar dependence on the impact velocity and aspect ratio. However, the deformation pattern of five-fold nanowires is different from that of single crystal ones due to their pre-existing twin boundaries that serve as the barriers to block the activity of partial dislocations. Secondary five-fold twins can also form, and then be annihilated during the bending process. Furthermore, unique microstructures such as bi-conjoint and multi-conjoint five-fold twins are observed, indicating that pre-existing fivefold twin boundaries may play an important role in facilitating the formation of secondary five-fold twins.
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