Microstructures and mechanical properties of extruded 2024 aluminum alloy reinforced by FeNiCrCoAl3 particles

Different proportions of commercial 2024 aluminum alloy powder and FeNiCrCoAl3 high entropy alloy (HEA) powder were ball-milled (BM) for different time. The powder was consolidated by hot extrusion method. The microstructures of the milled powder and bulk alloy were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties of the extruded alloy were examined by mechanical testing machine. The results show that after BM, the particle size and microstructures of the mixed alloy powder change obviously. After 48 h BM, the average size of mixed powder is about 30 nm, and then after hot extrusion, the average size of grains reaches about 70 nm. The compressive strength of the extruded alloy reaches 710 MPa under certain conditions of milling time and composition. As a result of the identification of the nano-/micro-structure-property relationship of the samples, such high strength is attributed mainly to the nanocrystalline grains of a(Al) and nanoscaled FeNiCrCoAl3 particles, and the fine secondary phase of Al2Cu and Fe-rich phases.