Study on the effect of milling parameters on the microstructure evolution of AlFeCoCrNi high-entropy alloy

During the milling process of AlFeCoCrNi high-entropy alloy, the material undergoes complex thermomechanical loads, leading to significant microstructural changes such as dynamic recrystallization, dislocation accumulation, and grain refinement. Understanding the mechanisms behind these microstructural evolutions is crucial for optimizing machining parameters and enhancing surface quality. This study aims to explore the effects of milling parameters on the machining process and microstructural changes in the AlFeCoCrNi high-entropy alloy. A three-dimensional milling model of the AlFeCoCrNi high-entropy alloy was established using DEFORM finite element analysis. Single-factor experiments were conducted to investigate the influence of milling speed, depth of cut, and feed rate on temperature, milling force, dynamic recrystallization, and grain growth in the primary, secondary, and tertiary deformation zones. The results indicate that milling speed significantly impacts the temperature in these zones, with maximum increases of 21.9%, 127.88%, and 115.64%, respectively. The milling force is most affected by the depth of cut, showing an increase of 105.74%. Dynamic recrystallization near the P1 zone is greatly influenced by milling speed, with a growth rate of 78.28%. Grains sized between 1.975 mu m and 2.95 mu m were uniformly distributed, and larger grains in the tool-chip contact area were refined into smaller ones due to the milling speed. Grain growth near the P3 zone also notably increased with milling speed, rising by 73.28% as the speed increased from 186 to 270 m/min. When the speed exceeded 270 m/min, larger grains disappeared and split into grains sized between 1.975 mu m and 2.95 mu m. Furthermore, the depth of cut significantly influenced grain recrystallization near the P3 zone, with an increase of 81.12%. Larger grain boundaries near the P3 zone reduced and split into smaller grains. The grain growth rate near the P2 zone positively correlated with the depth of cut, showing a substantial increase of 663.15%. Dynamic recrystallization near the P1 zone increased significantly with the feed rate, showing a 32.55% rise as the feed rate increased from 0.2 to 0.4 mm/r. Meanwhile, grain growth near the P3 zone increased significantly with the feed rate, showing an increase of 269.93%, although grains larger than 2.95 mu m did not show significant relative movement with changes in the feed rate.