Strong interfacial bonding and high mechanical properties of copper-decorated carbon nanotubes reinforced AZ91 magnesium matrix composite

The poor interfacial adhesion and dispersion of carbon nanotubes (CNTs) limits the further improvement of performance in CNTs/Mg composite. In this work, strong interfacial binding and homogeneous dispersion of CNTs were obtained through the powder metallurgy method. AZ91 powder and copper-decorated CNTs were utilized as initial materials, combined with the ball milling process, vacuum hot-pressing, and extrusion. In situ interface reactions took place between the matrix alloy components and the plated copper particle of CNTs. This led to the creation of interface phases like AlCuMg, Al2CuMg, Cu0.61Zn0.39, Al2Cu, AlCu3 and Cu2Mg, alongside coherent interfaces such as AlCuMg/Cu2Mg. These interactions notably enhanced the strength of interfacial bonding. In addition, the uniform distribution of CNTs at a lower fraction was obtained by combining ball-milling technology and CNTs fraction control. Finally, a high-strength and toughness CNTs/AZ91 composite was prepared. The composite has better properties than those reported in literature.