Nanoparticulate Reinforced Aluminum Alloy Composites Produced by Powder Metallurgy Route

High energy planetary ball-milling was used to effectively disperse 3, 6 and 9 wt. % multiwall carbon nanotubes (MW-CNTs) into commercially available aluminum alloys (Al6061, AlMg5, S250 and S790). Composite bulks were manufactured by uniaxial hot pressing. For the Al6061- CNT composites, standard heat treatments (T4, T5 and T6) were performed and their influence on the structural evolution (grain coarsening, CNT reaction) and hardness was recorded. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Raman spectroscopy were used to characterize the produced composites. The study shows that CNTs can be effectively mixed with high-strength aluminum alloys. Up to 5 fold increase in hardness was achieved compared to unreinforced alloys ranging up to 390 HV20 for the S250 alloy with 6 wt. % of MW- CNTs. The applied standard heat treatments did not lead to any improvements of the mechanical properties. The developed nanocomposite materials could find applications where high hardness of aluminum is needed, or in functionally graded composites.