Microstructure and high-temperature deformation behavior of FeCoNiMnV high entropy alloy

Abstract

The microstructure and deformation behavior of the FeCoNiMnV high entropy alloy (HEA) was investigated using the compressive test at temperatures ranging from room temperature to 800 °C. The X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), and electron backscatter diffraction (EBSD) were used to analyze the structure and microstructure of the compressed samples. According to the XRD results, no specific phase transformation occurred during the hot deformation except for the second phase's partial dissolution. Up to 400 °C, the samples exhibited a relatively high strength with a small amount of ductility, demonstrating good thermal and structural stability. At 600 °C and 800 °C, the flow behavior of the alloy changed remarkably. Peak stress, followed by a gradual decline in flow stress, was observed at elevated temperatures, suggesting the occurrence of the dynamic recrystallization (DRX). The formation of grain boundaries with a high misorientation angle, the evidence of the grain growth, and the large fraction of the coherent twin boundaries confirmed the occurrence of DRX during the compression test. The flow curves at high temperatures were analyzed based on the Avrami kinetics of recrystallization. The Avrami exponent was determined as 1.668 and 1.135 for the samples compressed at 600 °C and 800 °C, respectively.