To achieve high strength in metal matrix composites (MMCs), transition metals have been considered because reinforcing efficiency of nano-carbon materials in transition metal reinforced MMCs is more remarkable than that of any other MMCs.
Transition metals such as Ti, Fe, and Ni have a strong interface with nano-carbon materials because of strong interfacial bonding between the unoccupied d-orbital in transition metals and the p-orbital in nano-carbon materials. Especially, carbon nanotubes (CNTs) have outstanding mechanical properties (i.e., young's modulus (~1TPa)). Thus, in this study, CNTs are separately dispersed in each Ti, Fe, and Ni matrix by ball milling. Hot pressing is performed at relatively low temperature. The strength of the composites increases with an increment of CNTs volume fraction. As a result, it demonstrates that CNTs with an excellent interface in transition metals have a key role in reinforcing MMCs to improve mechanical properties.