Ductile-brittle transition of graphene architectures scaling from nanometer to micrometer scales, as revealed by in situ transmission electron microscopy
ICYS-MANA researcher (Sep. 2012 ~ Mar. 2015), MANA scientist (Apr. 2015 ~)
Graphene, as the thinnest and strongest material in the world, is promising for the mechanical applications. Various graphene architectures have been reported by assembling graphene building blocks to bulk scale. However, there is a large gap between the mechanical properties when the size scales up from atomic level to the macroscale level. Therefore, it is important to understand the scaling laws of the graphene mechanics in the range from nanometer to micrometer scales, that is, how the mechanical properties, deformation and fracture mechanisms are dependent on the size scale.
In the current work, we used in situ electron microscopy techniques [1-6] to investigate the mechanical properties of a high-density high-porosity graphene monolith with the sample size ranging from nanometer to micrometer. We show that at nanometer scale, the graphene monolith has high strength (up to 1.8 GPa) coupled with high plasticity (up to 48 %). With the size increasing from nanometer to micrometer scale, a transition in the deformation mechanism is discovered, from homogeneous plastic flow to localized quasi-brittle cracking.
1. D.-M. Tang et al., Proc. Natl. Acad. Sci. USA 107, 9055 (2010).
2. D.-M. Tang et al., ACS Nano 5, 7362 (2011).
3. D.-M. Tang et al., Nano Lett. 12, 1898 (2012).
4. D.-M. Tang et al., Nano Lett. 13, 1034 (2013).
5. D.-M. Tang et al., Nature Communications 5, 3631 (2014).