Combustion synthesis and characterization of nickel aluminide–carbon nanotube composites

In this work the feasibility of synthesizing carbon nanotube reinforced nickel aluminides with combustion synthesis was studied. In situ combustion synthesis and densification was conducted with reactive mixtures of nanosized nickel and aluminum with added carbon nanotubes. The effect of carbon nanotube type (single or multi-walled) and content, as well as the mixing methodology used, on the relative density, resulting microhardness, phase composition, and morphology were investigated. Composites synthesized with 1.0 wt.% single walled carbon nanotubes showed an increase in microhardness, over monolithic, of 30% using the optimized mixing procedure. Optimized mixing resulted in good distribution of the nanotubes at low percent additions as observed with scanning electron microscopy. We also observed crack bridging indicating that added carbon nanotubes have the potential to serve as toughening agents in combustion synthesized materials. Transmission electron microscopy and Raman spectroscopy of the synthesized composites confirmed that the carbon nanotubes retained their original structure after combustion synthesis though multilayer graphene nanoribbons were also observed.

► Combustion synthesis of nano-sized Ni and Al particles with carbon nanotubes. ► Carbon nanotubes are retained after combustion synthesis of CNT-reactive mixtures. ► Graphite nanoribbons result after combustion synthesis of CNT-reactive mixtures. ► Processing route for achieving CNT and graphite reinforced nickel aluminides.