Effect of Al/Cr ratio on structure, magnetism, and corrosion resistance of FeCoNiCr1-xAlx high entropy alloys

Abstract

This study investigates the microstructure, magnetic properties, and corrosion resistance of FeCoNiCr1-xAlx (x=0, 0.25, 0.5, 0.75, 1) high-entropy alloys using the combination of experimental methods and first-principles calculations. XRD results reveal the FCC-BCC phase transition as x increases, and FeCoNiCr1-xAlx exhibits a noticeable dual-phase structure when x=0.75. The partial segregation between Ni and Al elements is indicated by SEM-EDS observations. The magnetism of both FCC and BCC phases become strong with increasing x, and the BCC phase consistently exhibiting higher magnetism than the FCC phase. Potentiodynamic polarization curves show that Al0.25 has the highest corrosion potential and the lowest corrosion current density. Under open circuit potential conditions, due to the difference between the corrosion potential and the open circuit potential, the electrochemical impedance spectroscopy measurements indicate that the corrosion resistance of the alloys follows the order: Al0 > Al0.5 > Al0.75 > Al0.25 > Al1. Considering both the soft magnetic behavior and corrosion resistance, Al0.75 is a optimal choice. These findings provide valuable insights for developing magnetic high-entropy alloy materials with superior corrosion resistance.