Fabrication, mechanical properties and electrical conductivity of Al₂O₃ reinforced Cu/CNTs composites

Copper is widely used in many applications due to its excellent electric conductivity, processing ductility and corrosion resistance. However, poor hardness and low strength are the major limitations of copper in many fields. Herein, we report a high-performance copper matrix composites prepared by powder metallurgy. The copper matrix composites were prepared by mixed acid treatment, molecular-level method, ball milling and spark plasma sintering (SPS) process. The fabrication, microstructure, mechanical properties and electrical conductivity of the composites were investigated. The results show that nano-Al₂O₃ can act as an active mixing agent to disperse CNTs in copper powders and increase the adhesion between CNTs and copper matrix in composites. Additionally, the uniform dispersion of Al₂O₃ and CNTs can restrict the grain growth and form a strong bonding interface. Thus, the synthesized Cu-1.5CNTs-0.5Al₂O₃ composite displays the highest comprehensive performance, such as 131 HV hardness, 345 MPa ultimate tensile strength, 324 MPa yield strength, 13.8% elongation, and 50.6 MS/m (87.2%IACS) electrical conductivity. This work provides a feasible way to prepare high-performance copper matrix composites.