In situ nano-compression on pillars with nano-twinned copper
Tzu-Sheng Yeh1*, Yu-An Shen2, Chih Chen2, Yi-Chia Chou1
1Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
2Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
* presenting author:葉子聖,
For polycrystalline materials such as pure metal, the strength has a maximum value at a critical grain size. The strength decreases above and below the critical sizes results from the difficulty of lattice dislocation motion and grain boundary-related process, respectively. Here we study the mechanical property and microstructures of nanosized copper nanopillars with high density unidirectional 111 oriented nanotwins. Using in situ nano-compression setup in TEM, we will show the real time changes of microstructures and the corresponding mechanical property. It allows us to have detailed understanding of the strengthening mechanism of nano-twinned copper at atomic scale. We will show the deformation phenomena of such copper nanopillars under compression. We will discuss the measurement of the load-and-displacement on the nano-twinned copper and the resulted microstructures. In addition, we will discuss the Nabarro-Herring creep on such nanostructure where twin/grain boundary plays a critical role. We will show the calculation of the required energy of creep for different sizes of twin spacing.

Keywords: in situ TEM, nanotwin