Guangming Cheng1 Sheng Yin2 Huajian Gao2 Yong Zhu1

1, North Carolina State Univ, Raleigh, North Carolina, United States
2, Brown University, Providence, Rhode Island, United States

Metallic nanowires (NWs) have attracted much attention in recent years for a wide range of applications including flexible and stretchable electronics, where their mechanical behaviors are of important relevance. In this talk, we will present our recent work on in-situ transmission electron microscope (TEM) mechanical testing of crystalline metallic NWs, closely integrated with atomistic simulations. Using a unique nanomechanical testing stage based on the MEMS technology, we measure the stress-strain curves while simultaneously observing the microstructural evolutions. We identify dislocation nucleation from free surfaces as the dominant deformation mechanism. For single crystalline NWs, large plastic deformation is observed as a result of coherent twin propagation. In addition, we find that twin boundaries in the NWs play a critical role in the mechanical behaviors. In the case of bitwinned NWs that have a single twin boundary along the nW length direction, we observe a transition of deformation mechanism from localized dislocation slip to delocalized plasticity via an anomalous tensile detwinning mechanism.