Microstructure and mechanical properties of AA1050/AA6061 multilayer composites via accumulative roll bonding and cryorolling and subsequent aging

Abstract

AA1050/AA6061 multilayer composites were processed by combining accumulative roll bonding (ARB) and cryorolling, followed by aging. The microstructure evolution and mechanical properties of the multilayer composites were analyzed. The results show that cryorolling can enhance the mechanical properties of AA1050/AA6061 multilayer composites compared to ARB. Cryorolling first improves the interfacial flatness and delays the onset of plastic instability, enhancing the deformation uniformity between the constituent layers. Second, cryorolling can accumulate a higher dislocation density and achieve a remarkable grain refinement. Moreover, cryorolling significantly reduces the formation of delamination and promotes the quality of the bonding interface between layers. The combined effect of high dislocation density, uniform deformation ability, and good interfacial bonding gives cryorolled samples a considerably higher ultimate tensile strength than ARBed samples following peak aging treatment at multiple aging temperatures. Meanwhile, both the ARBed and ARB + cryorolled samples exhibit the best performance after aging at 100 °C. The increase in the ultimate tensile strength of AA1050/AA6061 multilayer composites at peak aging is mainly attributed to ultrafine grains and fine precipitates in the AA6061 layer.