About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
|
Symposium
|
Mechanical Behavior at the Nanoscale VI
|
Presentation Title |
In Situ Atomic-scale Observation of Surface-diffusion-controlled Softening in Metallic Nanocrystals |
Author(s) |
Scott X. Mao |
On-Site Speaker (Planned) |
Scott X. Mao |
Abstract Scope |
In nanoscale metals, it is generally believed that surface dislocation nucleation is the dominant mechanism. Thus far, the role of surface diffusion in the process of yielding and plastic flow in metallic nanocrystals remains largely unclear. Here,in situ nanomechanical testing under high-resolution transmission electron microscope was conducted on silver and platinum nanocrystals, we found that the yield strength-size relationship of the silver nanocrystals changed from a normal to an inverse Hall-Petch relation with the reduction of size scales. Surface diffusion-assisted dislocation nucleation and plastic flow resulted in an abnormal decrease in yielding and flow stress in Ag nanowires, whereas Pt nanowires followed the classical “Hall-Petch” routine, which is controlled by pure displacive deformation. This work provides novel insights into the atomic-scale mechanisms of coupled diffusive and displacive deformation in small-sized metals. |
Proceedings Inclusion? |
Planned: |
Keywords |
Nanotechnology, Mechanical Properties, Characterization |