The effect of inclination angle on the plastic deformation behavior of bicrystalline silver nanowires with Sigma 3 asymmetric tilt grain boundaries

L Yuan and P Jing and DB Shan and B Guo, APPLIED SURFACE SCIENCE, 392, 1153-1164 (2017).

DOI: 10.1016/j.apsusc.2016.09.123

Atomistic simulations were used to investigate the plastic deformation behavior of bicrystalline silver nanowires with Sigma 3 asymmetric tilt grain boundaries at 0.1 K. The calculated grain boundary energies of Sigma 3 asymmetric tilt grain boundaries corresponded well with the energies measured in experiments and predicted by the theoretical description. The Sigma 3 asymmetric tilt grain boundaries with low inclination angles were composed of a replication of twin boundary segments separated by small ledges. The results demonstrated that the combination effect of Schmid factor and non-Schmid factors could explain dislocations emission into grain 1 only in models with low inclination angles (Phi < 64.76 degrees). At the latter stage of plastic deformation, free surfaces served as additional dislocation sources. Parallelly arranged operative slip systems were the fundamental features of plastic deformation. In addition, a number of stacking faults and multiple stacking faults were formed during plastic deformation. The hindrance of stacking faults to dislocation motion and the interactions between dislocations leaded to the observed strain hardening in nanowires with inclination angles at and above 29.50 degrees . The low stacking fault energy of silver was responsible for the appearance of strain hardening. Dislocations emitted from grain 2 interacted with each other contributing to the observed strain hardening. Grain boundaries were completely eliminated by successive emission of dislocations from grain boundaries in nanowires with an inclination angle of 35.26 degrees and 54.74 degrees. A detailed understanding of the relationship between strength and grain boundary structures as well as specific plastic deformation would push forward the application of nanocrystalline materials and provide insights into the synthesis of nanocrystalline materials with superior strength and ductility. (C) 2016 Elsevier B.V. All rights reserved.

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