Plastic Deformation at the Nanoscale

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Plastic Deformation at the Nanoscale
Bin Chen,1,2, * Wenge Yang,1 Jialin Lei,3 Shizhong Yang,3 Yuanjie Huang,1 HansRudolf Wenk,4 Ho-kwang Mao1,5
1Center
for High Pressure Science and Technology Advanced Research, Shanghai
201203, China. *[email protected]
2Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, CA 94720,
USA.
3LONI Institute, Southern University, Baton Rouge, LA 70813, USA
4Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
5Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC
20015, USA
The size of nanocrystals provides a limitation on dislocation activity and associated
stress-induced deformation. Dislocation-mediated plastic deformation is expected to
become inactive below a critical particle size, which has been proposed to be between 10
and 30 nm based on computer simulations and TEM analysis. However, our deformation
experiments on polycrystalline nickel and magnesium aluminate suggest that dislocation
activity is still operative in sub-10 nm crystals. Texturing and associated dislocation
activities are observed for the first time in nanocrystals of a few nanometer sizes.
Especially, through in situ texturing and TEM observations of stressed bulk- and nano-sized
spinel ceramics, we find that dislocation activities become operative in nanoceramics. This new
finding is at odds with the conventional theory that dislocation mechanisms are suppressed in
ceramics.
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