Optimal corrosion resistance of cobalt-based dual-phase entropic alloys via compositional modulation of aluminum

A new category of Al-doped cobalt-based dual phase entropic alloys with high corrosion resistance properties was designed in the present work. CALPHAD (CALculation of PHAse Diagram) aided prediction was performed to facilitate the alloy design. Two groups of al-loys have been extensively investigated by various techniques. One group was quenched in water from the homogenization temperature (i.e. 1200 & DEG;C) to room temperature. The other group was subsequently quenched in liquid nitrogen from room temperature. The microstructure of the proposed alloys was characterized by X-ray diffraction (XRD). Several kinds of electrochemical tests were performed to study the corrosion behaviors of the designed alloys in NaCl solution, including open circuit potential (OCP), polarization and cyclic polarization curves, electrochemical impedance spectroscopy (EIS), electrochemical noise (ECN), linear voltammetry curves and staircase voltammetry scan, and Mott-Schottky method. The obtained results show that Al has a minor influence on the corrosion property of this series alloy with a 0 to 2 at.% Al addition. All the designed alloys hold quite acceptable corrosion resistance. In addition, a mechanical property, i.e. micro -hardness, is also provided as a supplement information. This work sheds light on the correlation between computational thermodynamics and corrosion behaviors in cobalt -based dual-phase entropic alloys, as well as to provide a feasibility study on the impor-tant role of CALPHAD method for a rapid development of a new category of high perfor-mance alloys.& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

A new category of Al-doped cobalt-based dual phase entropic alloys with high corrosion resistance properties was designed in this study. Computational thermodynamics aided prediction and various techniques were employed to investigate the alloys. The results showed that the designed alloys exhibited acceptable corrosion resistance and the addition of Al had a minor influence on their corrosion properties. This study sheds light on the correlation between computational thermodynamics and corrosion behaviors in cobalt-based dual-phase entropic alloys, and demonstrates the feasibility of using CALPHAD method for rapid development of high-performance alloys.