Microstructure characteristics and mechanical properties of Al0.25CrFeNi1.75Cux high-entropy alloys

Abstract

In this work, we study the microstructural evolution and mechanical properties of Al0.25CrFeNi1.75Cux (x = 0–0.7) high entropy alloys (HEAs). The microstructural analysis confirmed that high Cu doping altered the microstructure of alloys and evolved from single FCC phase to FCC matrix and AlCu-type phase characteristics. Al0.25CrFeNi1.75Cux alloys exhibited typical dendrite morphology, and at the high doping of Cu content, the average size of the dendrites and secondary dendrite arm spacing was significantly decreased. The mechanical properties of the Al0.25CrFeNi1.75 alloy with different Cu content were studied by tensile tests. When Cu addition concentration increases from 0 to 0.7, the yield strength and the ultimate tensile strength increased by 35.4% and 12.1%, respectively. However, the elongation decreased by 47.2%. Enhanced mechanical characteristics were obtained due to a combination of the fine grain strengthening, the second-phase hardening of AlCu-rich precipitation, and the solid-solution strengthening.