Development and characterization of sustainable AA7075 aluminium alloy based composites reinforced with date palm ash through stir casting

A sustainable approach to improve the material properties of AA7075 aluminium alloy by reinforcing with heat treated date palm ash (DPA) powder is presented in this study. Date palm waste derived ash was used as a low-cost reinforcement after heat treating at 700 °C for 6 hours to eliminate volatile matter and enhance its thermal stability. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction techniques confirmed that the heat-treated DPA can be effectively incorporated as a reinforcement in AA7075 alloy matrix. Aluminium matrix composites (AMCs) were fabricated through stir casting process with varying weight fractions of DPA (1 wt.%, 2 wt.%, and 3 wt.%). Microstructural analysis revealed homogenous dispersion of reinforcement particles, grain refinement and good interfacial bonding between matrix and reinforcement up to 2 wt.% DPA addition. Consequently, these composites exhibited significant improvement in ultimate tensile strength (UTS), compression strength and hardness values compared to base alloy. However, further increase in reinforcement content resulted in non-uniform distribution of particulates, particle clustering, and poor wetting, which degraded the mechanical properties of AA7075- 3 wt.% DPA composite. Among the composites fabricated, AA7075- 2 wt.% DPA samples exhibited the highest improvement in mean Vickers hardness (27.74%), UTS (66.91%) and compression strength (34.17%) compared to the corresponding values of as-cast alloy. Utilizing DPA reinforcement in AMCs enhances the material properties, valorizes agricultural waste, and offers a sustainable alternative to high-cost synthetic ceramic reinforcements.