Development of Cu-TiO2 surface nanocomposite by friction stir processing: Effect of pass number on microstructure, mechanical properties, tribological and corrosion behavior

In the search of enhancing the surface properties of metals, application of the friction stir processing (FSP) method could be a good choice. In this study, copper-TiO2 surface nanocomposite was successfully developed through FSP and the effects of pass number on its microstructure, mechanical properties, tribological and corrosion behavior were explored. To characterize the microstructure of the composites, optical microscopy (OM), and field emission scanning electron microscopy (FESEM) were utilized. Mechanical properties in the terms of microhardness and tensile test were investigated. Results showed that by increasing the pass number of FSP, a significant enhancement in mechanical properties of the samples has occurred. In comparison to the pure copper, the microhardness, yield and tensile strength values using 4-pass FSP were found to improve 77%, 33%, and 186%, respectively. In addition, increasing the FSP pass number led to the reduction of the sample's elongation. The wear properties of the surface composites were found to the great enhancement by increasing the pass number. In addition, the corrosion results showed that the surface nanocomposite after 4 passes FSP had much high corrosion resistance.