Damping Property of AA6061/SiCp Surface Composites Developed through Friction Stir Processing

The processing route has an influence on the damping capacity, and in this study, the influence of silicon carbide particle (SiCp) size on the damping capacity of AA6061 processed through friction stir processing was investigated. Specimens were extracted from the stir zone and analyzed for their damping properties, and the same was correlated with the obtained microstructures. The samples were also characterized for the change in dislocation density, plastic zone size, grain boundary area and crystallite size through x-ray diffraction and electron microscopy. The average grain size remarkably reduced after friction stir processing (45 to 5.64 μm) and it further decreased with an increase in reinforcement particle size (9, 29.4 and 109 µm). The damping capacity was measured through dynamic mechanical analyzer from 25 to 300°C and was observed to increase for the samples subjected to friction stir processing and with increasing particle size. It was found that the plastic zone radius around the SiC particle increased with the particle size, and the contribution of plastic zone was found to be significant than the dislocation density for damping below 125°C.