Microstructures and Mechanical Properties of CNT/AZ31 Composites Produced by Mechanical Alloying

In this study, the mechanical properties and hot extrusion of carbon nanotubes (CNTs)-reinforced Mg (AZ31) based composite were investigated. To improve the mechanical properties of the Mg alloy AZ31, CNT /AZ31 composites were fabricated by mechanical alloying and hot extrusion process. Then, extrudates of these composites were formed using a hot-extrusion process. The conditions to prepare the extruded specimens, which were rod-shaped, were at extrusion temperature of 400 C, an extrusion ratio of 19: 1, and a ram speed of 1.0 mm/s. A 300 ton press was used for an extrusion. The microstructures were observed using by optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The characterization of the hot-extruded CNT/AZ31 rods was performed through electrical resistance and tensile test. The extruded CNT/AZ31 rods showed significantly improved ultimate tensile strengths and yield strengths, but the exhibited an elongation of less than 2%. These results were due to the formation MgO between Mg and the CNTs during themechanical alloying process.