Enhancing tribological, mechanical, and microstructural properties of AA6061 composites with ceramic reinforcements (CrC, NbC, TaC) through friction stir processing

This study investigates the potential of employing ceramic particles (CrC, NbC, and TaC) and their combinations to enhance several properties of AA6061 aluminum alloy during friction stir processing (FSP). FSP greatly enhances the reduction in the grain size compared to the original metal. Adding ceramic particles to the material strengthens the resistance to grain growth; thus, FSP significantly reduced grain size compared to the base metal by an average of 91.98%. In particular, composites containing TaC and a combination of CrC and TaC have the smallest grain size, possibly due to the combined impacts of these materials. Nevertheless, there were difficulties in the dispersion of particles, as they tended to be distributed randomly during FSP. Adding ceramic particles can significantly decrease friction compared to the alloy without reinforcement, but the extent of the decrease depends on the type and amount of ceramic particles added. Hybrid composites consisting of CrC and TaC have the most minimal friction coefficient. This hybrid also demonstrated exceptional mechanical properties, with increased stiffness by 34.7% and shear strength by 34.1% compared to the base alloy. Microhardness was significantly enhanced by up to 55.90% with reinforcements, particularly in the CrC + TaC hybrid and TaC composites. The microhardness is improved substantially by including reinforcements, with the hybrid CrC + TaC composites and TaC demonstrating the most substantial gains. The results indicate that adding ceramic particles, specifically CrC and TaC, dramatically enhances the wear resistance, mechanical strength, and microstructural characteristics of the AA6061 aluminum alloy.