Stress-assisted discontinuous grain growth and its effect on the deformation behavior of nanocrystalline aluminum thin films

Unique mechanical properties have been measured in submicrometer freestanding nanocrystalline Al films, where discontinuous grain growth results in a fundamental change in the way in which the material deforms. In contrast to the limited ductility normally associated with nanocrystalline metals, these nanocrystalline films exhibit extended tensile ductility. In situ X-ray diffraction and postmortem transmission electron microscopy point to the importance of stress-assisted room temperature grain growth in transforming the underlying processes that govern the mechanical response of the films: nanoscale deformation mechanisms give way to microscale plasticity.