Review on Grain Size- and Grain Boundary Phenomenon in Unusual Mechanical Behavior of Ultrafine-Grained Al Alloys

In the last three decades, several severe plastic deformation (SPD) procedures have been developed and applied in materials science to create bulk, ultrafine-grained (UFG) structures. As a consequence of SPD, not only submicron even nanometer grain sizes can be obtained, but also new boundaries with non-equilibrium structures material may formed. Therefore, both strength ductility UFG change significantly compared coarse-grained counterparts. This review is focused on unusual mechanical behaviors Al alloys, associated boundary structure segregations which are responsible for modification Hall-Petch relationship so-called size-effect structure. Unusually high strain rate sensitivity, intensive sliding superplasticity at low temperature described surveyed. addition, innovation potential these phenomena briefly considered.