Letter abstract
Nature Materials 8, 95 - 100 (2009)
Published online: 18 January 2009 | doi:10.1038/nmat2370
In situ observation of dislocation nucleation and escape in a submicrometre aluminium single crystal
Sang Ho Oh1,2, Marc Legros3, Daniel Kiener1,5 & Gerhard Dehm1,4
'Smaller is stronger' does not hold true only for nanocrystalline materials1 but also for single crystals2, 3, 4, 5. It is argued that this effect is caused by geometrical constraints on the nucleation and motion of dislocations in submicrometre-sized crystals6, 7. Here, we report the first in situ transmission electron microscopy tensile tests of a submicrometre aluminium single crystal that are capable of providing direct insight into source-controlled dislocation plasticity in a submicrometre crystal. Single-ended sources emit dislocations that escape the crystal before being able to multiply. As dislocation nucleation and loss rates are counterbalanced at about 0.2 events per second, the dislocation density remains statistically constant throughout the deformation at strain rates of about 10-4 s-1. However, a sudden increase in strain rate to 10-3 s-1 causes a noticeable surge in dislocation density as the nucleation rate outweighs the loss rate. This observation indicates that the deformation of submicrometre crystals is strain-rate sensitive.
- Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstr. 12, 8700 Leoben, Austria
- Division of Electron Microscopic Research, Korea Basic Science Institute, 52 Eoeun-dong, Daejeon 305-333, Korea
- CEMES-CNRS, 29 rue Jeanne Marvig, 31055 Toulouse, France
- Department Materials Physics, Montanuniversität Leoben, Jahnstr. 12, 8700 Leoben, Austria
- Present address: Department of Chemistry and Biochemistry, University of Munich, Butenandtstr. 5-13 (E), 81377 Munich, Germany
Correspondence to: Sang Ho Oh1,2 e-mail: shoh@kbsi.re.kr; e-mail: sanghooh@naver.com
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