In the present study, friction stir processing (FSP) was used for the incorporation of Ni particles into an A413 alloy to fabricate an A413/Ni/Al 3 Ni composite. Preliminary tests were conducted at a constant traverse speed of 20 mm/min and rotation speeds of 2000 and 1400 rpm. The microstructural evaluations were performed optical and scanning electron microscopes. After these investigations, the suitable range for the rotation speed and the traverse speed, were selected as 1250-2000 rpm and 8-80 mm/min, respectively. The design of experiments was carried out based on the 1-3? and three passes. Taguchi?s optimization method was used to achieve the maximum hardness and wear resistance (minimum weight loss values) at room temperature. The results of the optimization revealed that the optimum parameters for both hardness and weight loss were the rotation speed of 2000 rpm, the traverse speed of 8 mm/min and the tilt angle of 2°. Furthermore, the effect of the number of passes on the microstructure, microhardness and wear resistance was studied at room temperature and 250?C. Single pass, three-pass and five-pass FSP were conducted on the samples. For the evaluation of microstructures, optical microscopy and scanning electron microscope were utilized. Also, for the investigation of intermetallic formation, energy dispersive spectroscopy was used. Microstructural observations revealed that the FSP led to significant breakup of acicular Si particles and elimination of ? Al dendrites. It was found that the hardness and wear behavior of A413 cast alloy were strongly influenced by applying FSP. Also, the in situ formation of Al 3 Ni particles during FSP was a critical factor controlling the wear mechanism. Sliding wear tests revealed that the increase in the number of passes created a homogeneous distribution of Al 3 Ni intermetallic particles and thereby resulting in a significant improvement in wear resistance at both room and high temperatures. Hence, wear resistance of the five-pass sample at room and 250?C temperatures were more than twice and triple respectively than that of the base alloy. Keywords: Friction stir processing, A413 aluminum alloy, Al 3 Ni intermetallic compound, taguchi method
