In situ atomic-scale observation of dislocation behaviors in twin-structured Pt nanocrystals

The deformation mechanisms of twin-structured metallic materials have attracted great interest. Though previous theoretical predictions have suggested that the repulsive force of the twin boundary (TB) can significantly affect the deformation of twin-structured metals, it remains unclear whether this prediction applies to experimental conditions. In this paper, the atomic-scaled deformation process of twin-structured Pt nanocrystals was in situ observed using our home-made device in a high-resolution transmission electron microscope. We have shown that the plastic deformation of the twin-structured Pt nanocrystals was governed by full dislocation generation as well as Lomer dislocation (LD) lock formation and destruction. After LD locks were destructed, these full dislocations tended to move towards the surface of the nanocrystals. The findings revealed that due to the ultra-high repulsive force of TB on dislocation, there was no dislocation-TB reaction during the deformation. These findings can enrich our understanding of the dislocation behaviors of twin-structured nanocrystals.