Microstructure and Reciprocating Wear Behavior of 6061Al Matrix Composites Reinforced With AlCoCrFeNi 2. 1 High Entropy Alloy Particles

6061Al matrix composites reinforced with 4–13 wt.% AlCoCrFeNi 2 .1 high‐entropy alloy particles (HEAp) were fabricated by high‐energy ball milling followed by spark plasma sintering (SPS). The effects of HEAp content on phase constitution, microstructure, relative density, Vickers hardness, and reciprocating wear behavior were investigated. XRD analysis revealed Al 13 Co 4 , Al 8 Cr 5 , and AlCr 4 intermetallic phases after SPS, consistent with reactions during sintering. The particles were relatively uniformly distributed at HEAp contents up to 10 wt.%, whereas more pronounced local particle clustering was observed at 13 wt.%. The relative density increased from 97.5% to 98.7% and then decreased to 98.0%, while the Vickers hardness increased from approximately 71–83 HV. Among the investigated composites, the 10 wt.% sample exhibited the lowest average friction coefficient (0.407) and specific wear rate (1.31 × 10 −4 mm 3 /(N · m)), with the latter approximately 67% lower than that of the 4 wt.% composite. At 13 wt.%, the specific wear rate increased despite the higher hardness, suggesting that hardness alone cannot fully explain the observed wear behavior.