Characterization of mechanical and corrosion behaviour of multilayered Cu/Al/Al2O3 nano-composite produced by ARB process

In this research, the ARB process was used to produce Cu/Al/Al2O3 nano-composite. For this purpose, the rolling process was performed in multistep. In the beginning step, the surface of Al and Cu plates were prepared and then in the second step, three pieces of Al plates were put between four pieces of Cu plates and the boundary of plates was filled with alumina powder. In the third step, these layers were shaped as sandwich layers and rolled. The sandwiches were then cut into half and surface treatment was performed on them. Then, two halves of the composite were overlaid together and then rolled again. The rolling process was conducted for nine cycles. Microstructure and mechanical properties of each composite were analysed during each rolling cycle. Microstructural analysis was carried out via optical microscopy (OM) and scanning electron microscopy (SEM). Mechanical properties at various cycles were evaluated by tensile and hardness tests. Phase analysis of the samples was performed by using X-ray diffraction (XRD) analysis. Additionally, the corrosion behaviour of the composites was investigated at different cycles.
The obtained results showed that by repeating the rolling cycles, the thickness of reinforced aluminium layer decreased and this layer was distributed in the final cycle as a consequence of fracture. In addition, Al2O3 powder was uniformly distributed into the matrix. By increasing the number of the cycles, the structure of the composite was crashed and approximately decreased to 31.26 nanometers in the final cycle. By using the ARB process, the amount of ultimate tensile strength and hardness of composite increased to 420 Mpa and 140 HV as compared with the aluminium plates (252 MPa and 55 HV), respectively. The dominant form of corrosion in this composite is pitting corrosion and thus, the resistance of products prepared via the ARB process against the pitting corrosion is low.