Strain-rate dependence of tensile ductility of cryomilled 5083 Al alloys

The mechanical properties of nanostructured or ultrafine-grained (UFG) materials have engendered increased interest for the past two decades. Inspection of numerous published studies reveals that there is a strong effect of strain rate on the mechanical properties of nanostructured or UFG materials. In many cases, it is found that the tensile ductility increases with increasing strain rate and the strain rate sensitivity exponent is larger than that in their counterpart coarse-grained materials. In the present study, the mechanical properties and microstructural characterization of several bimodal nanostructured 5083 Al alloys processed from cryomilled nanostructured powders are investigated. It is noted that there are higher values of ultimate tensile strength and ductility at slower strain rates in the cryomilled 5083 Al alloys. The relationships among mechanical proper-ties at different strain rates, microstructural characteristics and deformation mechanisms of these materials are thus explored in the present study.