In situ experimental mechanics of nanomaterials at the atomic scale

Sub-micron and nanostructured materials exhibit high strength, ultra-large elasticity and unusual plastic deformation behaviors. These properties are important for their applications as building blocks for the fabrication of nano-and micro-devices as well as for their use as components for composite materials, high-strength structural and novel functional materials. These nano-related deformation and mechanical behaviors, which are derived from possible size and dimensional effects and the low density of defects, are considerably different from their conventional bulk counterparts. The atomic-scale understanding of the microstructural evolution process of nanomaterials when they are subjected to external stress is crucial for understanding these 'unusual' phenomena and is important for designing new materials, novel structures and applications. This review presents the recent developments in the methods, techniques, instrumentation and scientific progress for atomic-scale in situ deformation dynamics on nanomaterials, including nanowires, nanotubes, nanocrystals, nanofilms and polycrystalline nanomaterials. The unusual dislocation initiation, partial-full dislocation transition, crystalline-amorphous transitions and fracture phenomena related to the experimental mechanics of the nanomaterials are reviewed. Current limitations and future aspects using in situ high-resolution transmission electron microscopy of nanomaterials are also discussed. A new research field of in situ experimental mechanics at the atomic scale is thus expected. NPG Asia Materials (2013) 5, e40; doi:10.1038/am.2012.70; published online 15 February 2013