Fabrication and mechanical properties of MWCNTs-reinforced aluminum composites by hot extrusion

Over the past decade, the interest in aluminum composites reinforced with carbon nanotubes has grown significantly. Studies have been carried out to overcome problems with uniform dispersion, interfacial bonding, void formation and carbide formation of the composites. In the present work, multi-wall carbon nanotubes (MWCNTs) aluminum composites were produced. High-energy ball milling with the aim at developing well-dispersed MWCNTs Al composites was followed by cold compaction, sintering, and hot extrusion at 500 degrees C. Different amounts of stearic acid as processing control agent (PCA) is used in order to minimize cold welding of the Al particles, and to produce finer particles. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were employed to analyze the MWCNTs, the aluminum powder, and the composites' microstructural behavior. The hardness and tensile properties of the composites are also evaluated. The results showed 500% increase in yield stress after the addition of 1 wt% MWCNTs in Al-MWCNTs based composite. The ball-milling time of 4 h is found to be sufficient as excessive milling time destroys a vast number of MWCNTs.