Size Effect and Deformation Mechanism in Twinned Copper Nanowires

Metals

Huan Liu¹  Dan Song¹  Jiapeng Sun¹  Aibin Ma¹  Xiaowei Yang¹  Cheng Li¹  Xiaoyan Shao²  Jing Han³ 

[1] College of Mechanics and Materials, Hohai University, Nanjing 210098, China;School of Engineering and Technology, China University of Geosciences, Beijing 100083, China;School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, China;

关键词: twinning;    nanowire;    molecular dynamics;    plasticity;    ductility;    fracture;   

DOI  :  10.3390/met7100438

来源: DOAJ

【 摘 要 】

Molecular dynamics simulations were performed to demonstrate the synergistic effects of the extrinsic size (nanowire length) and intrinsic size (twin boundary spacing) on the failure manner, yield strength, ductility and deformation mechanism of the twinned nanowires containing high density coherent twin boundaries CTBs paralleled to the nanowires’ axis. The twinned nanowires show an intense extrinsic size effect, i.e., shorter is stronger and more ductile, and an intense intrinsic size effect, i.e., thinner is stronger. Notably, the strengthening effect degradation of CTBs in the twinned nanowires is observed with an increase in nanowire length: remarkable strengthening effect can be obtained for the short nanowires, but the strengthening effect becomes less pronounced for the long nanowires. The twinned nanowires fail via a ductile manner or via a brittle manner depending on the synergistic effect of the nanowire length and twin boundary spacing. By atomic-level observation of the plastic deformation, we found that the emission of a trailing 30° partial from the free surface controls the yield behavior of the twinned nanowires. We also found that the special zigzag extended dislocations are formed by the dislocation–CTBs interactions, and propagate to sustain the plastic deformation.

【 授权许可】

Unknown