Feasibilty Study of AZ31/Al2O3 Surface Nanocomposite Fabrication Via Friction Stir Processing

Friction stir processing (FSP) was used to fabricate AZ31/Al2O3 nanocomposites for surface applications. The effects of probe profile, rotational speed and the number of FSP passes on nanoparticle distribution and matrix microstructure were studied. Three tool designs, non-threaded, threaded and three flutes were used. The grain refinement of matrix and improved distribution of nanoparticles were obtained after each FSP pass. By increasing the rotational speed, as a result of greater heat input, grain size of the base alloy increased and simultaneously more shattering effect of rotation, cause a better nanoparticle distribution. In the non-threaded and three flutes FSP tool due to absence of threads some voids was observed. XRD results show that the reinforcement volume is low. Also, the texture of FSPed samples changes significantly. Some fluctuations were measured in the hardness values which are due to banded structure of the stir zone. With increase of rotational speed a smoother hardness results was produced.