Microstructure evolution and mechanical properties of Al/Al–12%Si multilayer processed by accumulative roll bonding (ARB)

Abstract

In this study, multi-layered Al/Al–12%Si composites were produced by the accumulative roll bonding (ARB) at ambient temperature using commercial pure Al 1050 and Al–12%Si alloy sheets. The microstructures of Al and Al–12%Si alloy layers were characterized by scanning electron microscopy (SEM). Vickers microhardness and tensile tests were conducted to investigate mechanical properties of the composites. It was observed that by increasing ARB cycles, thickness of individual Al and Al–12%Si alloy sheets decreased; finally, Al–12%Si layers were necked at the second cycle. After the second ARB cycle, a multi-layered Al/Al–12%Si composite with homogeneously distributed Al–12%Si layers in aluminum matrix was produced. Si phase was refined from 65.6 to 25.57µm in length and the Al grain size was reduced from 25 to 7.2μm. The formation of Al3.21Si0.47 intermetallic phase after the second cycles was confirmed by X-ray diffraction. The results showed that the tensile strength increased up to 270MPa after first cycle and dropped afterwards. Microhardness measurement indicated that hardness of individual layers increased continuously with increasing the ARB cycles.