Physical and Mechanical Characterization of a Nano Carbon Infused Aluminum-matrix Composite

A nanocarbon-infused aluminum-matrix composite, termed "covetic," has been developed by Third Millennium Metals, LLC, and we have evaluated the enhanced performance prospects for strength and electrical conductivity. This paper examines the effects of the nanoscale carbon on the physical, electrical and mechanical properties of the metal-matrix composite based on microscopy, hardness, quasi-static tensile strength, high strain-rate compression strength and electrical conductivity measurements. In the as-extruded condition (warm worked at 400°F) the results show that the nanocarbon provides approximately a 30% improvement in yield strength compared to baseline 6061-T0. High strain rate, Split Hopkinson Pressure Bar (SHPB) tests revealed an opposite trend-the as-extruded covetic exhibited lower stresses at equivalent strains. In the T6 condition, the strength and ductility of 6061 with and without nanocarbon are approximately equal at all strain rates. The nanoscale carbon increased the electrical conductivity of 6061 by 43% in the as-extruded condition, but by only about 1% in the T6 condition. Electron microscopy showed that the covetic 6061 was more resistant to grain growth and coarsening during extrusion. The carbon/aluminum composite displays potential as an improved strength aluminum alloy with much higher electrical conductivity than is typical for other aluminum alloys and aluminum matrix composites.