Enhanced mechanical and electrical properties of super-aligned carbon nanotubes reinforced copper by severe plastic deformation

Abstract

For conducting materials, achieving both high strength and high electrical conductivity has remained challenging due to the mutual exclusivity between these two properties. Here, we demonstrate the possibility of adjusting dislocation distribution by severe plastic deformation (SPD) at room temperature to improve both mechanical strength and electrical conductivity of super-aligned carbon nanotubes (SACNTs) reinforced copper matrix composites. After rolling, a high tensile strength (470 MPa) combined with a high electrical conductivity (98% IACS) was achieved. Strain hardening, which mainly resulted from dislocation accumulation, is the major strengthening mechanism after rolling. The increase of electrical conductivity of composites is a result of a combined effects of the elongated grains, repressed dislocation generation and regulated dislocations distribution. The formation of ultra-low dislocation density regions in the rolling direction, which can be attributed to the strengthening effect of SACNTs during rolling, provided a much more efficient channel for conducting electrons. Scalable production of composites with high mechanical strength and high electrical conductivity can be achieved by using this method.