Improving anti-corrosion properties of CoCrFeMnNi high entropy alloy by introducing Si into nonmetallic inclusions

The microstructures and composition at and around inclusions in casted CoCrFeMnNi alloy were studied. It was found that the Cr-depletion zone caused by the formation of MnO·Cr2O3 was responsible for the corrosive catastrophe of the alloy. Si was introduced in the alloy to modify the microstructure and composition of the inclusions. Instead of forming harmful MnO·Cr2O3, stable amorphous MnO-SiO2 was formed in the Si-added CoCrFeMnNi, eliminating the Cr-depletion zone. Consequently, the corrosion resistance of the Si-added CoCrFeMnNi was largely improved. The present work reveals a way of increasing corrosion resistance by modifying inclusions that disrupt the homogeneity of passive films. Data availability statement: All research data supporting this publication are directly available within this publication.