Processing, microstructural evolution, and tribological behaviour of high-entropy alloy-reinforced aluminium composites fabricated via powder metallurgy and hot compression
Abstract
High-entropy alloy (HEA) reinforced aluminium matrix composites have emerged as promising alternatives to conventional ceramic-reinforced systems for tribological applications. In the present study, CuCrFeMnNi high-entropy alloy particles (HEAp) were employed as metallic reinforcements in an Al–Zn–Mg–Cu aluminium matrix fabricated via a powder metallurgy route. High-energy ball milling was used to mechanically alloy the matrix powders and synthesize nanocrystalline HEAp, followed by hot pressing at optimized conditions to achieve dense composites. The evolution of powder morphology, phase constitution, and chemical homogeneity during milling was systematically investigated using SEM, EDS, and XRD analyses. The consolidated composites exhibited uniform HEAp dispersion, refined grain structures, and strong matrix–reinforcement interfacial bonding up to an optimal reinforcement level. Mechanical characterization revealed a significant enhancement in hardness with increasing HEAp content, while tribological evaluation demonstrated improved wear resistance and reduced coefficient of friction under dry sliding conditions. Among the investigated compositions, the composite containing 10 wt.% HEAp exhibited the best balance of hardness and wear performance. The incorporation of HEAp significantly improved the hardness and wear resistance of the composites, with the 10 wt.% HEAp composite exhibiting the highest hardness of 227.85 HV compared to 140.04 HV for the base alloy. The optimized composite also demonstrated significantly reduced wear loss and coefficient of friction under dry sliding conditions. The superior tribological behaviour was attributed to grain refinement, increased dislocation density, dual-phase FCC–BCC HEA reinforcement, and the formation of a protective tribo-oxide layer during sliding. This study establishes a comprehensive process–microstructure–tribological property relationship and highlights the potential of HEA-reinforced aluminium composites for advanced aerospace and tribological applications.