MECHANICAL FATIGUE AND MICROSTRUCTURE BEHAVIOR OF CASSAVA PEEL SiO₂ STRENGTHENED FRICTION STIR WELDED AA6065–Al₂O₃ METAL MATRIX COMPOSITE JOINTS

This study investigates the mechanical fatigue and microstructural behavior of friction stir welded (FSW) AA6065–Al 2 O 3 metal matrix composites (MMCs) reinforced with cassava peel-modified SiO 2 . The research aims to enhance the mechanical properties and fatigue resistance of the composite while evaluating the impact of surface-modified cassava-derived SiO 2 as a sustainable reinforcement material. The incorporation of bio-filler during FSW is a novelty of this study. The performance of the composite is evaluated in accordance with the ASTM standard. According to the study, the welded composite C3 of AA6065–5[Formula: see text]wt.% Al 2 O 3 with 3[Formula: see text]wt.% biosilica exhibits superior properties, such as 282[Formula: see text]MPa tensile strength, 248[Formula: see text]MPa yield strength, 5.1% elongation, 22.5[Formula: see text]J impact strength, and 186[Formula: see text]MPa fatigue strength. When compared to the basic specimen A1, it has 18.48% more tensile strength, 31.91% greater yield strength, 60.78% less elongation, 38.03% greater impact strength, and 36.74% higher fatigue strength. However, compared to plain welded composite A1, the composite with 5[Formula: see text]wt.% biosilica incorporation exhibits an improvement in hardness strength of 127, which is 38.04% greater. Following mechanical testing and weld joints, the material performance and particle dispersion are determined by SEM and microstructural analyses. The findings suggest that cassava-derived SiO 2 can serve as an eco-friendly reinforcement, offering a cost-effective alternative for lightweight structural applications.