Abstract
Multiscale nanostructured materials containing multimodal grain size distributions can be engineered to display unusual balance of properties, such as strength and ductility. Despite well documented reports of enhanced ductility in multiscale nanostructured materials, systematic identification of the underlying deformation mechanisms has not been accomplished. In this work, we selected high-purity Cu and commercial pure Ti as a model material system in an effort to elucidate the underlying mechanisms. The multimodal Cu and Ti were prepared by equal-channel-angular pressing (ECAP) and subsequent annealing. In situ atomic force microscopy (AFM) in combination with tensile testing and ex situ transmission electron microscopy (TEM) are used to characterize the deformation mechanisms and mechanical behavior.