Investigating the hardness and tribological behavior of Al / Al2O3-TiB2 nano-composite surface produced via friction stir processing

In this study, the new method of via friction stir processing (FSP) was used to create a composite surface layer of Al / Al2O3-TiB2. The microstructural variation, distribution of reinforcement particles and adhesion of the composite layer to the substrate, were investigated via optical and scanning electron microscope. Hardness results showed that the nanocomposite layer hardness was increased for 70% as compared with the primary aluminum and reaches the hardness of 95 in Vickers method due to the grain refinement as a consequence of the dynamic recrystallization and existence of the hard ceramic particles of Al2O3-TiB2. To study the wear behavior of nanocomposite samples, primary aluminum and friction stirred possessed aluminum wear investigated via the reciprocating wear testing machine and the predominant wear mechanisms and wear rate of the samples were compared with each other. The results show a significant increase in wear resistance of nanocomposite layer of Al / Al2O3-TiB2 due to the higher hardness and grain refinement due to the recrystallization in the stirred areas.