Influence of Oxide Dispersions (Al2O3, TiO2, and Y2O3) in CrFeCuMnNi High-Entropy Alloy on Microstructural Changes and Corrosion Resistance

This study investigates the influence of 3 vol.% Al2O3, 3 vol.% TiO2, and 3 vol.% Y2O3 in the CrFeCuMnNi equimolar high-entropy alloy on its microstructural changes and corrosion resistance. These oxide-dispersed high-entropy composites (ODS-HECs) were synthesized via high-energy ball milling (50 h) followed by uniaxial hot-compaction (550 MPa, 45 min), medium-frequency sintering (1100 degrees C, 20 min), and hot forging (50 MPa). The microstructures of the developed composites produced a stable FCC phase, a small amount of ordered BCC-B2 structure, Fe2O3, and corresponding dispersed oxide phases. The corrosion of the developed high-entropy composites was tested in 3.5% NaCl solution using several electrochemical techniques. The results revealed that the corrosion rate (R-Corr) decreased with the incorporation of oxide particles. Among the investigated samples and based on the electrochemical impedance spectroscopy results, CrFeCuMnNi-3 vol.% TiO2 ODS-HECs were seen to possess the highest value of corrosion resistance (R-P). The change in the chronoamperometric current with time indicated that the CrFeCuMnNi alloy suffered pitting corrosion which decreased when Al2O3 was added, forming a CrFeCuMnNi-3 vol.% Al2O3 sample. In contrast, the incorporation of a 3 vol.% Y2O3, and 3 vol. TiO2, prevents pitting.