Microstructure evolution of multilayered composite sheets of AA1050/AA7050 Al alloys produced by Asymmetric Accumulative Roll-Bonding

Abstract In this investigation, AA1050/AA7050 multilayered composite sheets were produced by Asymmetric Accumulative Roll-Bonding (AARB) in order to evaluate microstructure evolution and the interfacial zone. The asymmetric rolls introduced an extra component of shear strain, which provided conditions for necking and/or rupture in the AA7050 layers during processing at 500 °C yielding a wavy-pattern. On the other hand, at 450 °C the continuity of layers was maintained. Thus, AARB parameters can be controlled to produce wavy- or flat-pattern structures in multilayered composites. The hardening of the AA7050 layers after processing at 450 °C was caused by overaging and grain refinement, whereas at 500 °C it was due to the precipitation of η’ and η-phases. The hardening of the AA1050 layers was attributed to grain refinement achieved from continuous dynamic recrystallization. In addition, diffusion bonding has a significant role in the formation of AA1050/AA7050 interfaces by the AARB process, as observed in the interdiffusion zone. Taken together, these findings provide insights into structural pattern formation and microstructural control in Al-based multilayered composites using the AARB process.