A Co-free Cr-Fe-Ni-Al-Si high entropy alloy with outstanding corrosion resistance and high hardness fabricated by laser surface melting

In this paper, a CrFeNiAl0.2Si0.2 high entropy alloy (HEA) was fabricated via laser-surface melting (LSM). The result shows that, this HEA could form fully BCC structure under such rapid-solidification condition. Moreover, it exhibits excellent corrosion resistance in 3.5 wt% NaCl solution with two-stage passivation, and could maintain good protectiveness until 1.06 V vs SCE during electrochemical polarization, which is much higher than stainless steel. In addition, this rapid-solidified HEA shows high hardness of ∼667 Hv. Such excellent corrosion resistance and unique passivation process are possibly caused by the diversity in compositional constitution of the passive films under different electrochemical corrosion conditions. This work provides a novel route for designing low-cost corrosion-resistant HEAs with high hardness for coating applications.