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In situ observation of dislocation nucleation and escape in a submicrometre Al single crystal

Dear colleagues,
Experimental nanomechanics is a frequently discussed topic on imechanica, see e.g. the very active monthly topics by Xiaodong Li, Julia Greer and Wei Cai.
Continuing on this, I would like to draw your attention to a paper we recently published:
"In situ observation of dislocation nucleation and escape in a submicrometre aluminium single crystal" by Sang Ho Oh, Marc Legros, Daniel Kiener & Gerhard Dehm (http://www.nature.com/nmat/journal/v8/n2/abs/nmat2370.html).
We report the first in situ transmission electron microscopy tensile tests of a submicrometre Al 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.


As Sang Ho stated (like probably someone else I don't know before):
A picture tells more than 1000 words, but a movie tells the whole story!


So have a look at our in-situ movies and strain rate results and let me know if you need additional information!

Best,

Daniel

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