Microstructure and properties of 6061 aluminum matrix composites reinforced with core-shell AlFeNiMnCu0.5 high entropy alloy particles

In this study, the BCC AlFeNiMnCu0.5 high entropy alloy (HEA) was used as the reinforcement phase, and spark plasma sintering (SPS) technology was used to prepare core-shell structure and non-core shell structure composites at different sintering temperatures. The microstructure, mechanical properties, wear properties and corrosion properties of two composites with different mass fractions were studied. The formation and growth mechanism of the diffusion layer were obtained and analyzed. Experimental results manifested that the core-shell structure improved the comprehensive properties, especially plastic strain. The 15 wt% HEA/6061Al composite achieves a yield strength of 282 MPa and a plastic strain of 27.4 %, demonstrating enhancements of 35 % and 71 %, respectively, over the composite lacking the core-shell structure. Compared to the 6061Al (9.27 × 10−4 mm3/(N·m)), the 10 wt% core-shell composite exhibits a significantly lower wear rate of 0.64 × 10−5 mm3/(N·m). In terms of corrosion resistance, the composite with the core-shell structure exhibits a distinct passivation range and excellent resistance to pitting corrosion in a seawater environment. However, when the HEA content reaches 20 wt%, the performance of the core-shell structure composites decreases more significantly. Additionally, nanoindentation tests revealed that the diffusion layer exhibits higher nanohardness(13.46 GPa) and elastic modulus(185.59 GPa) than the HEA core, enabling it to effectively bear loads and inhibit crack propagation during compression tests. This work provides a new experimental basis and theoretical insight into the preparation and application of HEA-reinforced 6061 Al composites.