Journal Published Online: 25 March 2014
Volume 3, Issue 1

Physical and Mechanical Characterization of a Nanocarbon Infused Aluminum-Matrix Composite



A new class of nanocarbon-infused materials, termed covetics, has been developed by Third Millennium Materials, LLC. In this paper we have evaluated the enhanced performance prospects for strength and electrical conductivity of a nanocarbon infused 6061 aluminum composite by comparing properties to those of 6061 aluminum. Unlike most metal matrix carbon composites, this material is unique in that the nanocarbon is so strongly bound to the metal that it is stable in the molten state. The proprietary manufacturing process is still in the early stages of development, and we had an opportunity to evaluate a limited amount of extruded 6061 aluminum covetic sample material. This paper examines the effects of covetic processing on the physical, electrical, and mechanical properties of 6061 aluminum using chemical, optical, and scanning electron microscopy, density measurement, microindentation hardness testing, electrical conductivity measurement, quasi-static tensile testing, and high strain-rate compression (Hopkinson bar) testing. In the as-extruded condition (warm worked at 227°C) the results show that the nanocarbon provides approximately a 30 % improvement in yield strength compared to baseline 6061-T0. This could be explained using electron microscopy observations which showed that the covetic 6061 was more resistant to grain growth and coarsening during extrusion. High strain rate, Split Hopkinson Pressure Bar (SHPB) tests revealed an opposite trend-the as-extruded covetic material exhibited lower stresses at equivalent strains. However, 6061 aluminum is not normally processed in the low strength as-extruded condition, so the covetic material was heat treated to the T6 condition. In the T6 condition, the strength and ductility of 6061 with and without 3 wt. % nanocarbon were approximately equal at all strain rates. Whereas the nanoscale carbon increased the electrical conductivity of 6061 by 43 % in the as-extruded condition, the conductivity only improved 15 %–19 % in the T6 condition. The nanocarbon/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. This study identified a clear need for standards development for the chemical analysis of nanocarbon in covetic materials.

Author Information

Brown, Lloyd
U.S. Naval Academy, Mechanical Engineering Department, Annapolis, MD, US
Joyce, Peter
U.S. Naval Academy, Mechanical Engineering Department, Annapolis, MD, US
Forrest, David
Department of Energy, Advanced Manufacturing Office, Washington, DC, US
Salamanca-Riba, Lourdes
Univ. of Maryland, Department of Materials Science and Engineering, College Park, MD, US
Pages: 17
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Stock #: MPC20130023
ISSN: 2165-3992
DOI: 10.1520/MPC20130023