Mechanism Studies and Fabrication of Carbon Nanostructures Incorporated into Al Alloys by Electrocharging Assisted Process*

The incorporation of carbon (C) nanostructures into Al alloys, such as Al6061 and Al1350, has the potential to further improve the mechanical and electrical properties of these alloys. Previously, we reported on a novel electrocharging assisted process to incorporate up to 10 wt% C into the crystal structure of Al 6061 alloys to form “Al Covetic”. The C has been proved to transform into graphitic structures with high percent of sp² bonding. The mechanism of Covetic conversion is controlled by a high current density which facilitates ionization of the C atoms and migration of the C ions similar to “electromigration in a plasma”. In this study, alternative C source, such as graphite powders or flakes, which are already crystalline, are used to obtain a network of C nanostructures that extends throughout the metal. Different fabrication conditions are tested, including different reaction time, the mode of current (pulsed vs constant), and different trajectories of the graphite cathode. The goal is to obtain the optimal condition to fabricate Covetic with uniform C distribution and better electrical and mechanical properties. Conductive AFM, nanomechnical and electrical resistivity measurements are performed on Covetic compared to the parent alloys.