Effects of carbon nanotubes addition on the composition and mechanical properties of AlMgB 14 ceramics

In this article, the AlMgB₁₄–carbon Nanotubes (CNT) composites were synthesized by means of the mechanical alloying (MA) and field activated and pressure assisted in-situ synthesis (FAPAS). The microstructure and component of the synthesized metallic ceramics were observed and determined using the X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). Further investigations on the mechanical properties of the composites showed that adding CNTs could not only increase the hardness of AlMgB₁₄, but also improve the fracture toughness. It was found that the addition of 0.5% CNTs could achieve the best reinforcing and toughening effect. The microstructure analysis on the composites with an addition of 0.5% CNTs revealed the mechanism for such effects, i.e., the addition of CNTs could refine the grain, promote the formation of network microstructure, and confine the crack deflection along the interface between the CNTs and AlMgB₁₄. Furthermore, the high quality, uniform dispersion, integrity and compatibility with matrix of the CNTs were the main factors that improved the fracture toughness of AlMgB₁₄-CNTs composites dramatically.