Microstructural evolution and mechanical characterization for the AlCoCrFeNi2.1 eutectic high-entropy alloy under different temperatures

Recently, there has been a lot of interest in the AlCoCrFeNi2.1 eutectic high-entropy alloys (EHEAs), which can achieve a good balance of strength and ductility. The relationship between the microstructure and mechanical properties of the alloy was established in this study by examining the microstructural evolution during heat treatment of 500-1000 degrees C. The results show that the alloy's microstructure remained unchanged when the heat treatment temperature was lower than 700 degrees C. With further rise above 800 degrees C, the B2(II) precipitates were inspected in the L1(2) matrix. Besides, L1(2II) started to be precipitated from the B2 matrix at 900 degrees C. The tensile test results conducted at 20-1000 degrees C showed that both the yield strength and ultimate tensile strength decreased as the temperature rose. As for the elongation, however, it increased dramatically when the testing temperature was over 800 degrees C, being attributed to the dynamic recrystallization. The results obtained provided a fundamental understanding of high-temperature properties for duplex HEAs.

Automated summary

There is currently a strong interest in the AlCoCrFeNi2.1 eutectic high-entropy alloys (EHEAs) due to their ability to achieve a balance between strength and ductility. This study aimed to establish the relationship between the microstructure and mechanical properties of the alloy by examining its microstructural evolution during heat treatment at temperatures ranging from 500-1000 degrees C. The results showed that the microstructure of the alloy remained unchanged at temperatures below 700 degrees C, but B2(II) precipitates were observed in the L1(2) matrix at temperatures above 800 degrees C. Additionally, L1(2II) started to precipitate from the B2 matrix at 900 degrees C. Tensile tests conducted at temperatures between 20-1000 degrees C revealed that both the yield strength and ultimate tensile strength decreased with increasing temperature. However, the elongation increased significantly at temperatures above 800 degrees C, which was attributed to dynamic recrystallization. These findings provide a fundamental understanding of the high-temperature properties of duplex HEAs.