Effect of Re-sintering Temperature and Carbon Nanotube Content on Mechanical Behavior Al-CNTs Nanocomposites

In the present investigation, the effect of re-sintering temperature and multi-walled carbon nanotubes (CNTs) content (0-12 wt.%) on the mechanical behavior of CNTs-reinforced aluminum (Al)-based nanocomposites (Al-CNTs) studied. Al-CNTs nanocomposites were produced by planetary ball milling followed and double-pressing double-sintering (DPDS) methods. The morphology of consolidated bulk nanocomposites was examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM). The microhardness and compressive strength increased by 49% and 46.3%, respectively, as re-sintering temperature was raised from 560 to 650 °C. Additionally, when CNTs (8 wt.%) were included, the tensile strength increased from 182 to 294 MPa (by 61%), comparable to that of unreinforced Al. The results show that consolidated bulk Al-CNTs nanocomposites re-sintered at 610 °C showed the highest mechanical properties with a reinforcement content of 8 wt.%. Microstructure evolution showed CNTs agglomerated in Al-CNTs (12 wt.%) nanocomposites, and the reaction between Al and CNTs at a re-sintering temperature of 650 °C caused a large interface of Al₄C₃ in the structure. The bridging and pull-out mechanism occurred between CNTs and Al matrix at fracture surfaces.