A356/TiO 2 Nanocomposite Fabricated by Friction Stir Processing: Microstructure, Mechanical Properties and Tribologic Behavior

In this research, the effects of friction stir processing (FSP) and nano TiO2 particles on the microstructure, mechanical and tribologic properties of A356 Al alloy were investigated. The starting dendritic structure transformed into the Al matrix with a uniform distribution of Si-rich particles due to FSP. The results showed that FSP improves the nano-hardness and elastic modulus by 11% and 6%, respectively. The combined effects of FSP and nano TiO2 could raise the hardness and elastic modulus of the composite by 87% and 16% with respect to those of the base metal. The law of mixture rule was modified to relate the hardness and elastic modulus of the composite to those of the constituents. The results of wear tests showed that the mechanism of wear changes from adhesive in the base metal to abrasive in the fabricated composite.