Using a newly developed nanoscale deformation device, atomic scale and time-resolved dislocation dynamics have been captured in situ under a transmission electron microscope during the deformation of a Pt ultrathin film with truly nanometer grains (diameter $d<\sim 10\mathrm{nm}$). We demonstrate that dislocations are highly active even in such tiny grains. For the larger grains ($d\sim 10\mathrm{nm}$), full dislocations dominate and their evolution sometimes leads to the formation, destruction, and reformation of Lomer locks. In smaller grains, partial dislocations generating stacking faults are prevalent.

• Received 19 April 2010

DOI:https://doi.org/10.1103/PhysRevLett.105.135501

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© 2010 The American Physical Society