Improvement of mechanical properties in aluminum/CNTs nanocomposites by addition of mechanically activated graphite

Carbon nanotubes reinforced aluminum nanocomposite was prepared by ball milling route. CNTs were initially mixed with mechanically amorphized graphite. Specimens were analyzed by X-ray diffractometry and Raman spectroscopy. Crystallite size and dislocation density were calculated by modified Warren-Averbach method. Carbide formation was semi-quantitatively investigated via Raman spectroscopy. A band located in 950 cm−1 was considered to be corresponded to Al4C3. Hardness of the samples was also evaluated using a Vickers micro-hardness tester. The hardness strengthening contributions were modeled to evaluate interfacial bonding between CNTs and the aluminum matrix. In specimens, including amorphized graphite, hardening was due to both work hardening and second phase strengthening otherwise, only due to work hardening. It was deducted that the amorphized graphite has a major role for mechanical properties improvement. This seems to be due to the formation of aluminum carbide at the interface which consequently increases adhesion of CNTs to aluminum.