Tuning the microstructure for superb corrosion resistance in eutectic high entropy alloy

In this work, we demonstrate that the corrosion resistance of the FeCrNiCoNb0.5eutectic high entropy alloy(EHEA) can be tuned by controlling the size of its eutectic structure. Through microstructure refinement, the EHEA exhibits a superb corrosion resistance in 1 M NaCl in terms of a very low corrosion current density and an ultra-high transpassviation potential, which outperforms a variety of other HEAs and conventional metals and alloys. At the fundamental level, the microstructure refinement results in a rapid formation of a thick and compact passive film with less Cl-adsorption on the EHEA, which results in significant enhancement in its corrosion resistance. The outcome of our research provides important insights into the design of corrosion resistant chemically complex alloys.