Due to the excellent properties of carbon nanotubes (CNT) such as their high tensile strength, low density, good electrical and thermal conductivity, they are an ideal reinforcement material for metal matrixes. One major aim of this study was hence to fabricate the CNT reinforced Cu matrix (CNT/Cu) composites by accumulative roll bonding (ARB). Prior to the application of ARB processing, the behavior of CNTs at the interface, and also the effect of the degree of thickness reduction and CNT content on the bond strength were evaluated by the peeling test. The microstructure and mechanical properties of the obtained composites were also studied. Microstructural investigations were performed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The microstructural parameters such as microstrain and sub-grain size were calculated using the Rietveld method. Uniaxial tensile and hardness tests were conducted to evaluate the mechanical properties of the composites. The results of the peeling test demonstrated that the bond strength increase by increasing the thickness reduction and decreasing the CNT content between the strips. With increase in the number of ARB cycles, a better distribution of CNTs was obtained in the copper matrix and also the bonding between CNTs and matrix improved. The results indicate that the average sub-grain size of the pure Cu and composite reduced from 97.1 and 90.7 nm (after the first cycle) to 82.7 and 66.9 nm (after the fifth cycle), respectively. With increasing the number of ARB cycles, the tensile strength and hardness of the ARB -processed pure Cu and Cu-0.5vol.% CNT composite showed a great improvement but their elongation decreased at first step and then increased at second step. The tensile strength of pure Cu and Cu-0.5vol.% CNT composite increased from 221.9 MPa (for the annealed sample) to 496.6 and 581.5 MPa (for five cycle ARB-processed sample), respectively. In addition, by increasing the volume fraction of CNTs, the tensile strength and hardness increased and then decreased. The SEM fractographic investigations revealed that the fracture mode after the first cycle for pure Cu and composite are combination of ductile and shear ductile fracture. However, with increasing the number of ARB cycles, the dimple size and the dimple depth decreased. Keywords: CNT/Cu composite, Accumulative roll bonding, Microstructure, Mechanical properties.
