Tribological Behavior of Annealed FeCoNiMn0.25Al0.25 High-Entropy Alloy

Abstract

High-entropy alloys have garnered significant attention from industry and academia, primarily due to their distinctive characteristics that offer prospects for future functional applications in the aerospace and automobile industries. The present work analyzes the impact of numerous annealed temperatures (800, 900, 1000 °C) on the microstructural evolution, phase formation, and tribological attributes of FeCoNiMn0.25Al0.25. According to X-ray diffraction studies, high-entropy alloys annealed at 800 °C and 900 °C produced dual phases, i.e., face-centered cubic (FCC) + body-centered cubic (BCC) solid solutions phase due to the presence of BCC precipitates in the FCC matrix. However, the sample annealed at 1000 °C exhibited a single-phase FCC solid solution. The electron back-scattered diffraction microstructure analysis indicates that, until 900 °C, there is no significant grain growth. Increasing the annealing temperature further results in a rise in average grain diameter, which significantly reduces microhardness. The inverse pole figure study reveals the existence of ⟨001⟩ and ⟨111⟩ texture in annealed high-entropy alloys. The coefficient of friction shows that high-entropy alloys annealed at 1000 °C have the lowest coefficient of friction because of the formation of tribo layers when sliding between two mating surfaces and avoiding direct contact between them. In addition, high-entropy alloy annealed at 1000 °C shows a decrease in the coefficient of friction by 8.5% and an increased specific wear-rate by 50% compared to the cold-swaged high-entropy alloy.