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 precoating 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 degrees 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.