Achieving high tensile elongation in an ultra-fine grained Al alloy via low dislocation density

An ultra-fine grained (UFG) 5083 Al produced by conventional extrusion of a fine-grained (FG) precursor exhibits a high tensile elongation (15.7% of uniform elongation in engineering strain) and a reasonably high tensile strength. In light of our results, the high tensile elongation is primarily attributable to the low dislocation density (5 x 10(12) m(-2)) in the UFG 5083 Al. The low dislocation density effectively improves the tensile elongation of an UFG material via two possible mechanisms: (i) enhancing the formation of dislocation tangling and (ii) minimizing the possibility of localized shear banding. Moreover, our results suggest that conventional plastic deformation of FG precursor materials provides a feasible approach for the synthesis of UFG materials that contain a low density of dislocations. (C) 2012 Elsevier B.V. All rights reserved.