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 × 1012 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.

► A very high tensile elongation was reported in an ultra-fine grained Al alloy.
► The high tensile elongation is attributable to the low dislocation density.
► It is feasible to make UFG Al alloys via extrusion of fine grained precursor.