Fabrication and investigation of microstructutr and mechanical properties of A356-TiO2-Gr surface Hybrid nano composite by friction stir processing

The A356 is a cast alloy which consist of aluminum, silicon and magnesium. This alloy has good strangth and ductility with excellent casting properties, high corrosion resistance and good fluidity. This alloy is wiedly used in the automotive industry, aircraft, defense industry and especially the automotive industry as a substitution of steel components. Poor wear resistance of the alloys is major limitation for their use. Friction stir processing (FSP) is a recognized surfacing technique as it overcomes the problems of fusion route surface modification methods. In this study, friction stir processing was utilized to incorporate TiO2 and graphite particles into the matrix of an A356 alloy to form surface hybrid nanocomposite. For fabrication of nanocomposite a constant tool rotation rate of 900 rpm and travel speed of 60 mm/min with a tool tilt angle of 3 degree was used. Keeping in view of the requirement for improving wear resistance of A356 alloy, friction stir processing was attempted for surface modification with TiO2 and graphite powders. SEM, metallography, hardness, nanoindentation and pin-on-disc wear testing were used for characterizing the surface of nanocomposite. Microstructural analysis showed a uniform distribution of reinforcement particles inside the nugget zone. The surface nanocomposite results in enhanced properties in mechanical properties and wear resistance compared to the behavior of the base metal. Addition of solid lubricant graphite improve tribological properties of the nanocomposite.