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

Abstract

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 °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 (RCorr) 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 (RP). 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.

Keywords

• high-entropy alloys
• oxide dispersions
• X-ray diffraction
• microstructures
• corrosion