Tuesday  |  Heritage E  |  09:00 AM–09:20 AM

#17506, In Situ TEM Investigation of Deformation Mechanisms in Polycrystalline Metallic Nanowires

The mechanical properties of nanowires are crucial for the performance and reliability of various technological applications. Understanding the mechanisms of deformation, plasticity and fracture in nanowires is of fundamental and practical importance. A number of recent studies have been reported on the mechanical behavior of single crystalline nanowires, either with or without twin boundaries. But reports on polycrystalline nanowires have been scarce. Here we employ MEMS-based in situ nanomechanical testing inside transmission electron microscope (TEM) to investigate the deformation mechanisms of polycrystalline Ag nanowires fabricated using the Jackhammer method. The fracture mechanisms in polycrystalline nanowires can be categorized into two distinct modes: necking-induced fracture and slip-mediated fracture. The effect of the grain boundary angle, grain orientation, and surface effects is investigated. Our results provide an in-depth understanding of the microstructural mechanisms governing plasticity, such as surface nucleation of dislocations and their interactions with grain boundaries and free surfaces. Our findings offer valuable insights into the effect of grain boundaries and free surfaces in dislocation mechanisms.

Hongyu Wang   North Carolina State University
Yong Zhu   North Carolina State University