Achieving ultrafine lamellar structure and exceptional electrochemical properties of Fe35Mn27Ni28Co5Cr5 high-entropy alloy through severe cold rolling process

Abstract

This research provides an insight into the effect of ultrafine lamellar microstructures on the electrochemical behavior of Fe35Mn27Ni28Co5Cr5 high-entropy alloys (HEAs) in a 0.5 M H2SO4 solution. Following the severe cold rolling (SCR) process at a reduction rate of 90 %, the Fe35Mn27Ni28Co5Cr5 alloy exhibited a predominantly lamellar microstructure aligned along the rolling direction, leading to variations in grain size and subsequent differences in electrochemical behaviors. The potentiodynamic polarization (PDP) plots and electrochemical impedance spectroscopy (EIS) measurements confirmed that the influence of heavy cold rolling on corrosion resistance was mainly attributed to grain refinement and residual stress. The corrosion resistance of HEAs was ameliorated as a result of increased rolling deformation. The 90 % cold-rolled specimen showed excellent comprehensive corrosion resistance, for which the Ecorr and icorr values were found to be −0.278 V and 329 µA/cm2. Consequently, the development of ultrafine lamellar structures provides better conditions for forming passive films with higher protection behavior compared with their other counterparts. It could be due to the improved surface conditions for the development of oxide films resulting from higher homogeneity. The present work will provide new opportunities for tailoring the electrochemical characteristics of HEAs with strong commercial viability.