Effect of ball milling on microstructure and mechanical properties of 6061Al matrix composites reinforced with high-entropy alloy particles

6061Al matrix composites reinforced by 7.5 vol.% nanocrystalline CoNiFeAl0.4Ti0.6Cr0.5 high-entropy alloy (HEA) particles have been synthesized by powder processing of powder mixture ball milled for 10 h, 20 h and 40 h. Results indicated that the average ultimate tensile strength and fracture strain of the 6061Al-HEA-10 h composite were 378 MPa and 8.4%, better than those of the 6061Al-HEA-20 h composite, which was related to the homogeneous distribution of HEA particles. Specifically, the 6061Al-HEA-40 h composite had the highest ultimate strength and yield strength, and the fracture strain was close to the 6061Al-HEA-20 h composite, related with the formation of fine HEA particle clusters and a heterogeneous grain structure. The strengthening mechanisms for the improved strength of the composites are mainly derived from the Hall-Petch effect and geometrically necessary dislocations.