Effect of Inter-Cavity Spacing and Heat Treatment in Friction Stir Processing/Welding (FSP/FSW) Al7075 Composites Containing Al2O3 and Graphene Nanomaterials using Charpy Impact Test

In this research, the friction stir process by adding Al2O3 and graphene nanoparticles at two different distances have been investigated. Nanoparticles are inserted in cavities with a diameter of 2 mm and a depth of 3 mm. Nanoparticles of Al2O3, graphene, and equal compositions of Al2O3 and graphene, each with two cavity spacings of 8 and 10 mm, have been performed in six different groups of friction stir process. From each group, Six Charpy specimens were separated. Charpy impact test was performed on six samples, three of which were heat-treated after the friction stir process. Charpy impact test has shown that the specimens have higher fracture energy after heat treatment. Also, in all cases, the fracture energy at the distance between the two cavities are10 mm more than the distance of 8 mm, this is since nanoparticles do not accumulate at a more distance. Also, to observe the resulting microstructures using optical microscopy and scanning electron microscopy on the friction welding process and the fracture surface of Charpy impact specimens were performed. The results show that the nanoparticles are accumulated in some samples and well dispersed in the materials in others.