Effect of High-Temperature Annealing on Microstructure and Mechanical Properties of Extremely Deformed Fe35Ni35Cr20Mn10 High-Entropy Alloy Wire

Fe35Ni35Cr20Mn10 high-entropy alloy wire with a diameter of 0.45 mm, prepared by continuous cold-drawing from a rod with a diameter of 6.34 mm, was subjected to high-temperature annealing at 600, 700, 800, 900, and 1000 °C for 1 h. The microstructure and mechanical properties in different states were investigated by microscopy observations and tensile testing. The wire in the as-drawn state exhibited the highest strength but the lowest elongation because of its fine multilayer structure and high dislocation density. Annealing, particularly at higher temperatures, considerably reduced the yield strength and caused significant recovery in both the elongation and strain-hardening exponent. Increasing the annealing temperature significantly decreased the dislocation density, notably coarsened the recrystallized grains, and significantly increased the fraction of twin boundaries and mean widths of annealing twins. The yield strength was found to be positively related to the dislocation density, and the elongation exhibited a negative relationship. In addition to the decrease in dislocation density, the formation of annealing twins played an important role in enhancing the elongation.