Mechanical Response and Microstructural Evolution of Aluminium Alloy Matrix Reinforced with Pulverized Periwinkle Shell Particulates

This study assessed the impact of pulverized periwinkle shell (PPS) particles as reinforcement for aluminium alloy. Experimental hardness test and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) were used for the mechanical and microstructural analysis. Vickers microhardness testing showed a high degree of internal consistency between experimental and computed results. The experimental and computed hardness of the base alloy 144.5/143.HV was reduced to 134.4/133.6 HV at 10% reinforcement and at 15%, it was further reduced to 125.7/124.7 HV. This was attributed to weak bonding and partial agglomeration. A peak hardness of 157.9/158.3 HV was achieved at 20% PPS, corresponding to the smallest mean indentation diagonal (0.0108 mm) and was attributed to optimal particle dispersion and stress transfer. At 25% PPS, hardness declined slightly (148.3/147.7 HV) due to clustering effects. The unreinforced alloy (0% PPS) was determined to be dendritic and compositionally homogenous (100 at. % Al). Elemental variety was introduced with the addition of PPS. At 25% reinforcement, up to five elements were found. 15% PPS showed grain refinement (~45–50 µm), but higher loadings (20–25 wt.%) resulted in localized particle aggregation and coarser grains (~60–70 µm).The findings show that the microstructure and mechanical behaviour of aluminium alloy were modified by PPS reinforcement. At 15–20 wt.% PPS, elemental distribution, microstructural refinement, and hardness were all effectively aligned, resulting in optimal performance and establishing PPS as an efficient and sustainable reinforcement for aluminium composites.