Matrix effect on strengthening behavior of carbon nanotubes in aluminum matrix composites

Many studies have shown that carbon nanotubes (CNTs) have excellent strengthening effect as a reinforcement in pure aluminum (Al). However, it is unknown that whether such merit can be also achieved in strong Al alloys for achieving higher-strength Al matrix composites. In this study, CNTs were incorporated into pure Al and a high-strength Al alloy (AA5083) via the same powder metallurgy route. Results showed that during the dispersion stage, the high energy ball milling process caused different amounts of deformation to pure Al and AA5083, which led to a better dispersion state of CNTs in powders and composites of pure Al. Although the two composites had the same tensile strength coincidentally, the reinforcing effect of CNTs in pure Al composite was more than five folds larger than that in AA5083, suggesting a strong matrix effect on strengthening behavior of CNTs in Al matrix composites. The present finding may show significant guidance for the optimization of fabrication processes and development of high-performance CNTs/Al composites.