Effect of recrystallization annealing on microstructure and properties of cold-deformed CoCrCu1.2FeNi high entropy alloy

In this paper, CoCrCu1.2FeNi high entropy alloy (HEA) was prepared by vacuum suspension melting. After 50 % cold-deformation, recrystallization annealing experiments involving the annealing temperatures of 650-950 degrees C and the annealing times of 30-120 min were carried out on the cold-deformed HEA. The microstructure and properties of the alloy were compared before and after annealing. The results showed that with the extension of annealing time and temperature, the microstructure of the alloy was gradually uniform and coarsening occurred after spheroidization. In addition, fusion and engulfment occurred in the microstructure and the microstructure size decreased first and then increased. Both the fracture strength and fracture strain of the alloy increased first and then decreased. The alloy had the best compression performance at 850 degrees C/60 min. Compared with the alloy after cold-deformation, the fracture strength was increased by 79.3 %, the fracture strain was increased by more than 1 time, and the comprehensive mechanical properties were the best at 750-850 degrees C. The average hardness decreased with the increase of temperature and annealing time, and the initial recrystallization temperature of the alloy was determined to be about 650 degrees C. The formation of annealing twins refined the microstructure and improved the properties of the alloy.