Effect of Friction Stir Processing on the Microhardness, Wear and Corrosion Behavior of Al6061 and Al6061/SiO2 Nanocomposites

An effect of the friction stir processing (FSP), its pass numbers and addition of the SiO2 nanoparticles on microhardness, wear behavior and corrosion performance of the Al6061 aluminum alloy was investigated. Scanning electron microscopy (SEM) and optical microscopy were utilized to characterize the microstructure of the alloy, FSPed and composite samples. SEM observations revealed that the SiO2 particles were not uniformly dispersed in the matrix after two passes of FSP. However, increasing the pass number more than two passes resulted in a great improvement in the distribution of the SiO2 particles. The application of FSP led to overall softening compared to the base metal. Softening of the Al6061 alloy was probably attributed to the coarsening of Mg2Si. Corrosion resistance of the FSPed samples found a significant reduction compared to the base metal. Applying higher pass number of the process and also addition of the SiO2 nanoparticles improved the wear behavior of the samples.