Compressive properties and behavior of copper nanowires wrapped by carbon nanotube
B Fu and ZH Zhang and LR Li and XM Qin and X Ye, APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 127, 787 (2021).
The mechanical properties of copper (Cu) nanowires (NWs) wrapped by carbon nanotube (CNT) under compression are studied by molecular dynamics simulations. By constructing a new structural model, which contains a Cu NW and a CNT that is denoted as CNT@Cu, the mechanical properties, deformation process and structural transformation are investigated in terms of stress-strain relationship, number of stacking faults (SFs) and dislocations, average bond length and atomic configurations. Results show that stress-strain exhibits two nonlinear elastic contraction stages and two intervening stages of inelastic deformation. The stress of Cu NW is almost not affected by the generation and migration activities of SFs but strongly depends on the increasing ratio of SFs due to the supporting of CNT. The inelastic plastic deformation is initiated by nucleation of partial dislocations on the 110 surface and then propagates to interior along the 111 close-packed planes. Wrapped by CNT, a unique structural transformation of compressed Cu NW is found, which is from < 100 > /111 to < 100 > /100 through the annihilation of 111 SFs planes and formation of 100 SFs planes along the 100 crystallographic orientations. The < 100 > /100-structured wire would undergo nonlinear elastic contraction until to a certain large strain, and then bend near the middle part before NW fractures eventually at a very high stain. What's more, the < 100 > /100-structured Cu NW possess high reversibility under unloading and an interestingly structural reverse transformation from < 100 > /100 to < 100 > /111 structure is observed prior to the fracture of NW at a high strain for the CNT@Cu model due the support of CNT. The ultimate compressive elastic strength of 100 (UCES-100) and ultimate elastic stain will decrease as the temperature increases from 10 to 500 K. The UCES of pristine (UCES-pristine) and UCSE-100 decrease as diameter decreases.
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