Fabrication of magnesium based composites reinforced with carbon nanotubes having superior mechanical properties

Magnesium (Mg) composite reinforced with carbon nanotubes (CNTs) having superior mechanical properties was fabricated using both pure Mg and AZ61 Mg alloy matrix in this study. The composites were produced via powder metallurgy route containing wet process using isopropyl alcohol (IPA) based zwitterionic surfactant solution with unbundled CNTs. The produced composites were evaluated with tensile test and Vickers hardness test and analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD). As a result, only with AZ61 Mg alloy matrix, tensile strength of the composite was improved. In situ formed Al2MgC2 compounds at the interface between Mg matrix and CNTs effectively reinforced the interfacial bonding and enabled tensile loading transfer from the Mg matrix to nanotubes. Furthermore, it was clarified that the microstructures and grain orientations of the composite matrix were not significantly influenced by CNT addition.

Research highlights
► Using the IPA based solution, the oxide-free pure Mg/CNTs composite powders could be prepared.
► The mechanical strength of the pure Mg composite reinforced with CNTs was not improved though the elongation was enhanced due to the elimination of MgO and less residual strain in the composite.
► The mechanical strength of the AZ61Mg alloy composite reinforced with CNTs was improved with maintaining adequate ductility due to the interfacial strengthening of Al2MgC2 ternary carbide.
► The CNT addition was not influenced on the microstructure and grain orientations of the AZ61 Mg alloy matrix.