Microstructure- and surface orientation-dependent mechanical behaviors of Ag nanowires under bending

The bending mechanical behaviors of Ag nanowires with different microstructures and surface orientations are investigated via molecular dynamics simulations. Our results show the fivefold twin boundary strongly hinders the dislocation motion, leading to the dislocation pile-ups at twin boundaries which is different from the results from tensile tests in which the fivefold twin boundary does not act as the substantive barriers for dislocation propagation and the dislocations can easily pass through twin boundary. The fivefold twin boundary strengthens the nanowires by strain hardening. In single crystalline nanowires, the dislocation nucleation sites and dislocation characteristics are determined by the loading directions and surface orientations. The different dislocation characteristics lead to different ductility when the same nanowire is loaded along different directions. The first order effect of surface orientation on the dominant deformation mode has not been observed in the present work. The stress gradient plays an important role on the different results observed under tension and bending.