Investigation of the electrochemical behavior of AlCoCrFeNi–ZrO2 high entropy alloy composites prepared with mechanical alloying and spark plasma sintering.

High entropy alloys, especially AlCoCrFeNi, have received much attention in recent years due to their unique properties. Therefore, the study of the various properties of this alloy has been the subject of recent fundamental research. In this study, the electrochemical behavior of zirconia-reinforced AlCoCrFeNi high entropy alloy has been investigated. For this purpose, the OCP and Tafel tests on the samples of AlCoCrFeNi-x wt% ZrO₂ (x = 0, 5, 10) were performed in a 3.5 wt% NaCl solution. The SEM images were obtained from the corrosion products. Subsequently, the samples were soaked in the above solution for 24, 48, and 72 h, followed by an impedance test. The results of the Tafel test and the SEM images show that the addition of zirconia up to 5 wt% and 10 wt% to the mentioned alloy decreases and increases the corrosion resistance, respectively. The increase in the FCC phase in AlCoCrFeNi-5 wt% ZrO₂ decreased the corrosion resistance. The improvement in corrosion resistance in AlCoCrFeNi-10 wt% ZrO₂ zirconia is due to the increase in the ceramic phase and the consistency between the passive layers. The EIS test showed that the addition of zirconia to the AlCoCrFeNi system delays the formation of passive layers by up to 72 h, as it leads to the formation of a rough surface. [ABSTRACT FROM AUTHOR]