Effect of Cold Rolling on the Microstructure Evolution, Mechanical, and Corrosion Properties of AlCoCrFeNi_2.4 High-Entropy Alloy

This study investigates the microstructure, mechanical, and corrosion properties of as-cast and cold-rolled \({\mathrm{AlCoCrFeNi}}_{2.4}\) high-entropy alloy at room temperature. The microstructure is examined using x-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy-dispersive x-ray spectroscopy (EDS). X-ray diffraction (XRD) analysis revealed that the constituent phases in the as-cast sample were FCC and BCC. The as-cast microstructure was observed to contain a primary FCC dendrite and a secondary FCC (\({L1}_{2}\)) + BCC (\({\mathrm{B}}_{2}\)) typical hyper-eutectic structure in the interdendritic region. Furthermore, the cold-rolled microstructure was severely deformed along the cold rolling direction. With the increase in thickness reduction from cold rolling, the microhardness, yield strength, shear strength, and ultimate strength of the alloy all increased, despite a decrease in ductility. Moreover, after the alloy was cold-rolled to 90%, the alloy demonstrated yield strengths of 1791 MPa, ultimate tensile strengths of 1956 MPa, and elongation to fracture values of 10.17%. In addition to these results, the as-cast sample demonstrated excellent corrosion resistance in a NaCl-based solution.