Mechanical and Tribological Properties of Synthetic and Agricultural Reinforced LM26‐AlN‐Coconut Shell Ash Hybrid Composites Fabricated via Powder Metallurgy Technique

In this study, LM26 Al‐alloy reinforced with 5 wt% aluminum nitride powder (AlN _P ) and varying coconut shell ash powder (CSA _P ) content (0.0, 1.5, 3.0, 4.5, and 6.0 wt%) is synthesized using powder metallurgy (P/M). The influence of these reinforcements on the physical properties, microstructure, mechanical behavior, and tribological performance of the composites is systematically investigated. Phase identification and elemental composition are assessed using X‐ray diffraction and energy‐dispersive spectroscopy, whereas field emission scanning electron microscopy is used to examine the powder morphology and microstructure of composites. The results indicate that increasing the CSA _P content led to a decrease in both green and sintered density, reaching values of 2.36 and 2.42 g cm ⁻³ , respectively. The composite containing 5 wt% AlN and 4.5 wt% CSA _P exhibits the highest microhardness (54.15 HV) and compressive strength (406.03 MPa), showing improvements of 26.23% and 119.80%, respectively. Fretting wear tests demonstrated that wear loss and the coefficient of friction (COF) decrease up to 4.5 wt% CSA _P , followed by an increase beyond this concentration. Furthermore, higher normal loads intensify both wear rate and COF. Worn surface analysis indicates that delamination and abrasion wear are the dominant mechanisms.