Size Effects on the Strength and Ductility of Nanocrystalline Materials
Yong-Wei Zhang (IHCP Singapore)
Materials for Extreme Environments: Multiscale Experiments and Simulations
Mon 9:00 - 10:30
Salomon 203
The strength of polycrystalline materials can be enhanced through refining their microstructures. Unfortunately, such procedure often leads to a decrease in ductility. Recent experiments have shown that at the nanoscale, refinement of materials can sometimes lead to unexpected outcomes, for example, a simultaneous increase in both strength and ductility in some cases while superplasticity in others. Such illusive outcomes are often attributed to the mechanism transitions dictated by size effects of microstructures. In this talk, we will report large-scale molecular dynamics simulations on both copper and silicon carbide nanocrystalline materials with aim to reveal the deformation mechanisms and size effects on the strength and ductility of these materials. In particular, we examine the changes in deformation mechanism due to the change in microstructure size, and how such change in deformation mechanism can lead to surprising properties, such as, simultaneous increase in both strength and ductility in nanotwinned copper and the superplasticity of nanocrystalline SiC at room temperature and under high strain rates. Based on the deformation mechanisms revealed by the atomistic simulations, continuum theories will be also presented to further reveal the mechanistic insights into such amazing changes of properties.