Effects of Twist Angles on Mechanical Properties of Cu Nanowires Under Tensile Loading
WW Pang and SY Yu and S Hussain and XY Yang and YZ Zhao, SCIENCE OF ADVANCED MATERIALS, 11, 954-960 (2019).
The tensile deformation behaviors of Cu nanowires with different twist angles are investigated using molecular dynamics simulations. It is found that square-like misfit dislocation networks form on the grain boundary, and the spacing of networks decreases with increasing twist angle. Plane defects form on the grain boundary instead of the misfit dislocations when the twist angle exceeds certain angle. The tensile simulation results show a stress relaxation fluctuation on the stress- strain curve before the stress peak in low-angle nanowires while converse for high-angle nanowires. This phenomenon is associated with the interface structures, dislocation nucleation and growth modes. For low-angle nanowires, the decomposition and slip of the misfit dislocations cause stress to decrease, while the nucleation of lattice dislocations from the interface results in decreasing of stress for high-angle nanowires. We find that the interface configuration has a significant effect on the interface strength. With increasing twist angles, the peak stress firstly decreases, then increases, and finally decreases. In addition, we also analyze the dislocation density curves and fracture mechanisms for nanowires with different twist angles.
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