This study aims to investigate the impact of partial-contact tool tilt angle (TTA) on the mechanical and microstructure properties of the AA1050 alloy friction stir weld (FSW). Three levels of partial-contact TTA were tested, 0°, 1.5°, and 3°, compared to previous studies on total-contact TTA. The weldments were evaluated using surface roughness, tensile tests, microhardness, microstructure, and fracture analysis. The results show that in partial-contact conditions, increasing TTA decreases the generated heat in the joint line and increases the possibility of FSW tool wear. This trend was the opposite of joints that were friction stir welded via total-contact TTA. The microstructure of the FSW sample was finer at higher partial-contact TTA, while the possibility of defect formation at the root of the stir zone in higher TTA was more than in lower TTA. The robust sample prepared at 0° TTA had 45% of AA1050 alloy strength. The maximum recorded heat in 0° TTA was 336 °C and the ultimate tensile strength of this sample was 33 MPa. The elongation of the 0° TTA welded sample was 75% base metal, and the average hardness of the stir zone was 25 Hv. The fracture surface analysis of the 0° TTA welded sample consisted of a small dimple, indicating the brittle fracture mode.

The utilization of Al₂O₃ nanopowder to reinforce AA5754 aluminum alloy through blind holes employing the friction stir processing (FSP) technique to produce an aluminum matrix nanocomposite is explored in this paper. Motivated by the necessity to enhance the strength and ductility of welded joints, the impacts of varying the tool rotational speed (rpm) and blind hole diameter on the microstructure and mechanical properties of the joints are investigated. Experimental characterization techniques including SEM, optical microscopy, microhardness, and tensile tests were employed to analyze the welded joints produced under different processing parameters (tool rotational speeds of 910, 1280, and 1700 rpm, and blind hole diameters of 0, 1, 1.5, and 2 mm). Comparative analyses were conducted against base metal properties and joints without reinforcement powder. It was found that the addition of nanopowder resulted in a decrease in the maximum generated heat during FSP, while also reducing the stir zone size compared to samples without nanopowder. Moreover, enhancements in both the strength and ductility of the joints were observed with the incorporation of Al₂O₃ nanoparticles. The optimal combination of welding conditions, observed at 1280 rpm rotational speed and 1.5 mm hole diameter, yielded a remarkable ultimate tensile strength of 567 MPa, accompanied by a hardness of 45 HV. These results underscore the potential of nano-Al₂O₃ reinforcement in significantly improving the mechanical properties of the produced nanocomposite, with implications for advancing the performance of welded structures in various engineering applications.

This study investigates the tribological properties of an AA 5754 aluminum alloy composite reinforced with the nanopowder of Al₂O₃, fabricated using the friction stir processing (FSP) technique with blind holes. The aim is to analyze the effects of varying the tool rotational speed (rpm) and blind hole diameter on the wear and friction behavior of the produced composite. A pin-on disk test is conducted under dry conditions and room temperature to assess the tribological properties against steel. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) is employed to examine the worn and wear surfaces of the produced composites post test. The results indicate that increasing the applied load results in a decrease in the coefficient of friction (COF), with values ranging from 0.775 to 0.852 for 10 N and 0.607 to 0.652 for 20 N. Moreover, the wear rate diminishes with higher Al₂O₃ content and optimal FSP tool rotation (1280 rpm). Hardness analysis reveals variations between 33–42 HV and 35–39 HV, influenced by nanoparticle distribution. The composite demonstrates superior wear resistance compared to raw AA5754 aluminum due to its reinforced nature. However, high FSP tool rotation rates lead to abrasive wear and surface cracks. These findings offer insights into optimizing FSP parameters to enhance the tribological performance of nano-reinforced aluminum alloys.