Ductile-brittle
transition of graphene architectures scaling from nanometer to micrometer
scales, as revealed by in situ transmission electron microscopy
Dai-Ming
Tang
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.
References
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).