Investigation of Temperature and Feature Size Effects on Deformation of Metals by Superplastic Nanomolding

We report a novel method to introduce feature size into the prevalent deformation-mechanism map by the super-plastic nanomolding technique. This new map enables various deformation mechanisms to be decoupled and allows for experimentally identifying the boundary between dislocation and diffusion dominated deformation regimes. Moreover, the proposed method provides a practical way to investigate the temperature effect on the mechanical properties of materials at small scales. As an example, the size-temperature-deformation mechanism map of gold is first determined by the proposed method. We found that the well-known Hall-Petch effect significantly weakens as the temperature increases. Besides, a transition from dislocation to diffusion dominated deformation regimes as the temperature increases is unambiguously revealed in the map, and the transition temperature is determined to be similar to 0.54T(m) for gold.