In Situ Observation of Dislocation Behavior in Nanometer Grains

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 < similar to 10 nm). We demonstrate that dislocations are highly active even in such tiny grains. For the larger grains (d similar to 10 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.