Evaluation of Mechanical Properties, Corrosion Resistance, and Microstructure of an Al 1Wt%Graphene- Al2O3 Hybrid Composite Sheet Produced by Accumulative Roll Bonding

In the present study, the Al/Al2O3/Graphene hybrid metal matrix composite was processed by accumulative roll bonding (ARB). A mixture of Al2O3 and Graphene (0.5 Wt% for each powder) was poured between two Al layers. The process continued up to five cycles, revealing particle-free zones and clusters in the composite’s microstructure. Increasing the ARB cycles improved the distribution of reinforcing particles in the aluminum matrix. Irregular porosities appeared in the early cycles and elongated in the middle ones. SEM investigation showed that better interface bonding in the last cycles increases internal stresses, promoting aluminum matrix flow and reducing porosities, crack sizes, and debonding. Mechanical tests such as tensile tests in RD directions, microhardness, fractography, and potentiodynamic corrosion tests in 3.5 wt-% NaCl solution have been performed to characterize the produced composites for the first time. Results showed that the tensile strength of the produced composites increases by increasing the ARB cycles and reaches the maximum value in the fifth cycle. Microhardness measurement indicated that the hardness of individual layers increases continuously by increasing the ARB cycles. The tensile fracture mode is a mixed fracture mode consisting of the cleavage and dimple rupture fracture in all cycles. The corrosion rate decreased from the first to the third ARB cycle relative to pure Aluminium alloy, arising from the presence of the inert particle and good bonding. However, it increased abruptly in the fifth cycle.