Abstract
Laminated metallic materials with an ultrafine‐grained (UFG) microstructure can easily be produced by accumulative roll bonding (ARB). Combining two different Al alloys, commercially pure (CP) and high‐purity (HP) aluminum, a layerwise bimodal microstructure is formed, where the CP layers consist of ultrafine grains whereas the HP layers show large grains as these layers undergo dynamic recrystallization during rolling. By applying different numbers of ARB passes and in addition by applying a subsequent heat treatment, the microstructure of the laminate can be changed significantly. Thus, different types of interfaces, specifically the grain boundaries of the ultrafine grains and the interfaces between the different layers of CP and HP aluminum are dominating the deformation behavior and the mechanical properties of these laminates. This article addresses how the UFG boundaries and the layer interfaces affect the mechanical properties under monotonic and cyclic loading, and discusses the relevant deformation mechanisms.
Highlights
Since the pioneering work of Gleiter,[1,2] the potential of nanocrystalline (NC) or ultrafine-grained (UFG) microstructures to within the original grains
During ARB processing, different textures evolve: The UFG commercially pure (CP) layers become dominated (S-type), whereas the HP layers show a cube orientation, which is typical for recrystallized aluminum
Tensile tests revealed that the yielding and the work hardening behavior are different for the N7 and N9 conditions in the AR state
Summary
Since the pioneering work of Gleiter,[1,2] the potential of nanocrystalline (NC) or ultrafine-grained (UFG) microstructures to within the original grains. Due to the HP and absence of defects, dislocation and grain boundary movement are not obstructed by atoms, precipitates, or intermetallic phases For this reason, the grain structure is coarsened by meta-dynamic recrystallization during rolling and cooling of the sheet.[23] Only after four cycles, the grain size decreases in the HP layers, as the grains growth is limited in the normal direction by the decreasing layer thickness.[22] Ruppert et al.[24] used the same material system but produced laminates with five times thicker layers than the material investigated by Chekhonin et al.[22] It turned out that for the thicker laminates, the grain size in the HP layers only decreases after six ARB cycles. This article addresses how the UFG boundaries and the layer interfaces affect the mechanical properties under monotonic and cyclic loading, and discusses the relevant deformation mechanisms
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