Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (11): 2015-2023.doi: 10.3866/PKU.WHXB201409101

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Molecular Dynamics Simulation of the Deformation Behavior of Ag Nanowires with Different Twin Boundary Density under Tension Loading

SUN Qian, YANG Xiong-Bo, GAO Ya-Jun, ZHAO Jian-Wei   

  1. School of Chemistry and Chemical Engineering, State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing 210008, P. R. China
  • Received:2014-06-25 Revised:2014-09-10 Published:2014-10-30
  • Contact: ZHAO Jian-Wei E-mail:zhaojw@nju.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21273113, 21121091) and National Key Technology R&D Program of China (2012BAF03B05).

Abstract:

The deformation mechanisms and mechanical tensile behavior of Ag nanowires containing different densities of parallel twin boundaries were investigated using molecular dynamics simulations. The effect of twin boundaries on the Young's modulus in nanowires was not obvious in the elastic deformation stage. After the elastic deformation stage, the initial dislocation from the edge of the free surfaces in nanowires resulted in plastic deformation. The existence of the twin boundary in nanowires will cause the spread of the dislocation and act as sources of dislocations with the assistance of the newly formed defects with further tension load. The simulation showed that the mechanical strength of Ag nanowires was highly dependent on the twin boundary spacing and the size of the grain, resulting from the aspect ratio between the spacing distance and the length of the cross-section. In particular, twinned Ag nanowires with small twin density (aspect ratio > 1) had small yielding stresses, even less than that of the single crystal Ag nanowires. Only with large twin density (aspect ratio < 1) can the nanowires be strengthened by the structure of the twin boundaries. We also investigated the effects of tensile rate and temperature on the yielding strength of the Ag nanowires. With increasing temperature, the difference of yielding stress between twinned nanowires and single crystal nanowires first increased and then decreased to a stable level. With increasing tensile rate, this difference showed the opposite trend.

Key words: Ag nanowire, Twin boundary, Uniaxial tension, Molecular dynamics simulation, Nanometer device, Aspect ratio

MSC2000: 

  • O641