In this work, an attempt has been made to fabricate hybrid Cu-SiC-Zn composites by friction stir processing technique. Through this investigation the different number of passes was applied to assess the effect of pass adding on the mechanical, microstructural and dislocation density behavior of the specimens. Formation of the intermetallic phases between the copper matrix and Zn particles was discovered through the processed specimens. According to the obtained results, the higher passes led to obtain more uniform dispersion of the SiC particles and intermetallic phases. This higher level of particles and intermetallic phases' distribution causes remarkable reduction of grain sizes through the composites. Dislocation density for the processed specimens was determined by using the hardness measurement method. The calculated values for the dislocation densities showed that presence of SiC particles and intermetallic phases could rise up the dislocation values. Measured microhardness values for the composites exhibit that they enhanced rather than base metal and these results were confirmed by dislocation densities values of the specimens.

The effects of Al2O3 reinforcements on microstructure, corrosion and toughness properties of dissimilar aluminum alloys joint fabricated by friction stir welding (FSW) technique were explored in this research. AA5083-H116 and AA7075-T6 were selected as the primary base materials. FSW was conducted with and without reinforcing particles through the joint line. Optical microscopy (OM) confirmed uniform distribution of reinforcement particles within the stir zone (SZ) of Al2O3-included specimen. It is demonstrated that the grain size of Al2O3-included specimen in SZ was smaller than that of fabricated without Al2O3. Besides, a comparative corrosion test was performed to assess the effectiveness of Al2O3 particles on corrosion resistance of the joint. The resultant polarization curves gave evidence to a perceptible enhancement in corrosion resistance of the Al2O3-included specimen. Fracture toughness, on the other hand, was examined through impact testing. Surprisingly, Al2O3-included specimen showed inferior impact toughness due to unsatisfactory bonding between matrix and reinforcements.