Pseudoelastic stacking fault and deformation twinning in nanocrystalline Ni

It is usually believed that the partial dislocation and deformation twin are the results of permanent plasticity in materials. Here, we present in situ atomic-scale observation of reversible stacking fault and deformation twin during loading and unloading in nanocrystalline Ni under high-resolution transmission electron microscopy. The high propensity for the reversibility of the stacking fault and deformation twin is due to the high stacking fault force and small grain size, and will provide an understanding at atomistic scale on the nature of the deformation in nanocrystalline materials. (C) 2010 American Institute of Physics. [doi:10.1063/1.3527976]