Regulating the interfacial reaction between carbon nanotubes and aluminum via copper nano decoration

The interfacial reaction plays a decisive role in the mechanical performances of the aluminum matrix composites reinforced with nano carbonaceous materials such as carbon nanotubes (CNTs). Due to the low Gibbs energy of Al₄C₃ formation and the required high-temperature processes for fabricating densified Al/CNTs composites, it is difficult to regulate the extent of the chemical reaction between Al matrix and CNTs, the dispersed CNTs are easily consumed to be Al₄C₃ rods. In this work, the Cu nano decoration on the surface of CNTs was proposed to restrict the massive formation of Al₄C₃. Raman results and systematical observations of transmission electron microscopy (TEM) revealed that the quantity and size of Al₄C₃ highly relate to the annealing time, and the pre-coating of Cu on the surface of CNTs can effectively limit the Al₄C₃ formation during the annealing process. Moreover, for the composite reinforced with Cu-coated CNTs, the microhardness, Young's modulus, and tensile properties can be optimized by controlling the annealing time. When the composite reinforced with Cu-coated CNTs was annealed at 550 °C for 12 h, the highest ultimate tensile strength (418 ± 6.5 MPa) together with good ductility (10.7 ± 0.3%) can be achieved, which can be mostly attributed to the limit formation of Al₄C₃. This work provides an effective approach to regulate the interfacial reaction in Al/CNTs composite and achieve higher mechanical performance accordingly.