Sustainable reinforcement of aluminium 6063 with plantain peel ash: Microstructural, mechanical, and corrosion performance

This study demonstrates that plantain peel ash (PPA) is a highly effective, low-cost reinforcement for aluminium 6063, delivering significant improvements across microstructural, mechanical, and corrosion performance metrics. The samples were fabricated via a two-step stir-casting process at 750 °C with 300 rpm stirring, followed by gravity casting. SEM and EDS analyses showed that PPA particles uniformly fill voids and refine the grain structure, while XRD confirmed the emergence of Al(MgO), intermetallic phases that bolster hardness and wear resistance. Hardness increased steadily with PPA content, reaching 38.2 HRB at 25 wt%, and wear rates fell by 66 % compared to the unreinforced alloy. Electrochemical testing across 30–60 °C revealed that PPA shifts corrosion potentials to more noble values and lowers corrosion current densities, indicating stronger surface passivation. Adsorption isotherm modeling supported a monolayer physical adsorption mechanism (ΔG_ads between –21 and –26 kJ mol^-¹) that is most effective at moderate temperatures. Post-corrosion optical microscopy confirmed that PPA dramatically reduces pit formation, with the 25 wt% composite displaying near-intact surfaces after exposure. Response surface methodology pinpointed an optimal formulation (24.992 wt% PPA at 30.012 °C) yielding a predicted corrosion rate of 0.47 mm yr^-¹ .