| About this Abstract |
| Meeting |
Materials Science & Technology 2020
|
| Symposium
|
Micro- and Nano-Mechanical Behavior of Materials
|
| Presentation Title |
Diffusion Induced Abnormal Softening Behaviors in Nanocrystals |
| Author(s) |
Sixue Zheng, Xiang Wang, Scott X. Mao |
| On-Site Speaker (Planned) |
Sixue Zheng |
| Abstract Scope |
Due to the high surface-to-volume ratio of nanocrystals, surface-related deformation mechanisms govern plasticity resulting in the well-known “smaller is stronger” power-law scaling in nanocrystals. As the sample size of nanowires (NWs) further went down to sub-ten nanometer, strong surface diffusion activities took place and influenced the mechanical behaviors. Here, by performing in situ high-resolution transmission electron microscopy (HRTEM) tensile testing, we revealed an inverse Hall-Petch relation in Ag NWs, while Pt NWs showed a traditional “Hall-Petch” size-dependent behavior. This difference resulted from surface atomic diffusion activities in Ag NWs, which may lower the critical stress for surface dislocation nucleation. To reveal the effect of surface diffusional creep on plastic flow, the coupled displacive-diffusive plasticity in Ag NWs and the pure displacive plasticity in Pt NWs were quantitatively investigated by analyzing the lattice stress-applied strain evolution in nanowires. |