Comparative Analysis on The Mechanical Properties and Microstructure of Al-Mg-Si Composites Reinforced with Groundnut Shell Ash, Palm Kernel Shell Ash, Avocado Pear Seed Ash and Alumina Particles

This study looks at the mechanical properties and microstructural aspects of Al-Mg-Si alloy matrix composites that are reinforced with Groundnut Shell Ash (GNSA), Palm Kernel Shell Ash (PKSA), Avocado Pear Seed Ash (APSA), and aluminium oxide (Al2O₃) particles. The composites were fabricated using stir casting and analyzed for porosity, hardness, tensile properties, and fracture behaviour. The percentage porosities increased for all reinforcements, with APSA showing the highest (31.1% increase) and PKSA the lowest (18.1% increase), while all values stayed within the acceptable limit for cast aluminium. Significant enhancements in hardness were observed, particularly in GNSA-reinforced composites (43.1% increase), confirming improved wear resistance. Al2O₃ exhibited the most significant improvement in ultimate tensile strength (39.2% increase), succeeded by PKSA (30.0% increase), demonstrating successful reinforcement. The specific strength reached its zenith with Al2O₃ reinforcement (60.1% increase), underscoring its exceptional load-bearing capability. In contrast, ductility, shown by strain to fracture, decreased in Al2O₃ (57.98% decrease) but dramatically increased with GNSA (80.8% increase) and APSA (69.8% increase), demonstrating enhanced energy absorption in agro-based composites. Fracture toughness significantly diminished in all samples, especially in APSA (274.3% decrease) and Al2O₃ (136.6% decrease), indicating increased brittleness due to the reinforcements. SEM examination demonstrated uniformly distributed particles throughout all matrices, reducing clustering and enhancing consistent mechanical performance. Agro-waste reinforcements exhibited commendable efficacy in improving mechanical properties while minimizing environmental impact; however, compromises in toughness should be acknowledged in design considerations.