Effect of carbon nanotube dispersion on mechanical properties of aluminum-silicon alloy matrix composites

This study has been carried out to reinforce the commonly believed fact that the dispersion of carbon nanotubes in a composite has a profound effect on the properties of the composite. In this study, ball milling was carried out using two different parameters to obtain distinctly different degrees of dispersion of carbon nanotubes (4 wt.%) in Al-9 wt.% Si powders. Composite disks, 80 mm in diameter, having good and bad dispersions of carbon nanotubes were obtained by hot pressing. Optical micrographs and Raman spectroscopy images showed the presence of larger carbon nanotube clusters in the bad dispersion sample. Transmission electron microscopy images confirmed the presence of large clusters in the bad dispersion sample, while the good dispersion sample showed individual carbon nanotubes in the Al matrix. Nanoindentation results indicated a 41% increase in the hardness and a 27% increase in the elastic-to-plastic work ratio, while compression tests indicated a 185% increase in compression yield strength and a 109% increase in fracture strength with improvement in carbon nanotube's dispersion. © 2013 ASM International.