Microstructure-property correlation in sustainable Al7075-T6 aluminium matrix composites reinforced with nanoscale banana peel ash derived from agro-waste

The development of lightweight aluminium matrix composites (AMCs) with improved mechanical performance and reduced environmental impact remains a significant challenge, particularly in replacing conventional ceramic reinforcements with sustainable and low-cost alternatives. This study investigates the potential of nanoscale banana peel ash (nano-BPA), derived from agricultural waste, as a sustainable reinforcement for Al7075-T6 aluminium matrix composites. Banana peels were dehydrated, calcined, and subjected to high-energy ball milling to produce nano-BPA with an average particle size of 20.2 nm. Al7075-T6 composites reinforced with 0, 2, and 4 wt% nano-BPA were fabricated by stir casting. The developed materials were evaluated using particle size analysis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), tensile testing, and Brinell hardness measurements. The results demonstrate a clear improvement in mechanical performance with increasing nano-BPA content. The ultimate tensile strength increased from 110 MPa for the unreinforced Al7075-T6 alloy to 197.5 MPa for the 4 wt% nano-BPA composite, representing a 79.5% increase. Similarly, Brinell hardness increased from 148 HBW to 173.11 HBW, corresponding to a 17.0% improvement. TGA confirmed the thermal stability of the nano-BPA, while SEM and EDS analyses revealed relatively uniform reinforcement distribution and effective matrix-particle interfacial bonding. Among the investigated compositions, the 4 wt% nano-BPA composite exhibited the highest tensile strength and hardness, together with satisfactory thermal stability and microstructural integrity. These results indicate that nano-BPA can effectively enhance the mechanical performance of Al7075-T6 while simultaneously utilizing agricultural waste as a value-added reinforcement.