Deformation behavior of bimodal nanostructured 5083 Al alloys

Cryomilled 5083 At alloys blended with volume fractions of 15, 30, and 50 pct unmilled 5083 At were produced by consolidation of a mixture of cryomilled 5083 At and Unmilled 5083 A] powders. A bimodal grain size was achieved in the as-extruded alloys in which nanostructured regions had a grain size of 200 nm and coarse-grained regions had a grain size of I mu m. Compression loading in the longitudinal direction resulted in elastic-perfectly plastic deformation behavior. An enhanced tensile elongation associated with the occurrence of a Luders band was observed in the bimodal alloys. As the volume fraction of coarse grains was increased, tensile ductility increased and strength decreased. Enhanced tensile ductility was attributed to the occurrence of crack bridging as well as delamination between nanostructured and coarse-grained regions during plastic deformation.