Carbon nanotubes (CNTs) could be an excellent reinforcement for metal matrix composites, specifically for composites with aluminum or aluminum alloy matrix. Surface modification to improve hardness and other material properties has been performed by laser surface melting (LSM) process, where the laser beam melts the substrate together with alloying elements or reinforcing phase additives. In this work, Multiwalled CNTs (MWCNTs) were mixed by the electrostatic adsorption process with aluminum powder and the resulting mixed powder was laser melted on the surface of a 6061-aluminum alloy substrate. As a result, a modified substrate surface has been obtained from the Al/MWCNT – substrate co-melting, dilution and re-solidification processes. This modified layer was obtained by different LSM parameters and were characterized by Optical (OM) and Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Field Emission Gun Scanning Electron Microscopy (FEG-SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy (RS). The resulting mechanical behavior was evaluated by Vickers microhardness tests. The results showed that the presence of MWCNT in the aluminum powder improves the laser energy absorption, leading to the formation of a deeper modified layer, with segregation of Si particles homogeneously dispersed and improving the hardness. The formation of Al 4C 3 was not observed, evidencing that the MWCNTs did not react with the molten Al matrix during the LSM process.
- Aluminum alloy
- Laser surface melting