Methods of Ni30Co30Fe15Mn15Ti5Al5 high-entropy alloys oxidation

Abstract The catalytic properties of High-Entropy Oxides in hydrogen and oxygen evolution reactions are so far promising. Even though the controlled oxidation of High-Entropy Alloys to fabricate High-Entropy Oxides on their surface is still briefly described in the literature. In this work, three different techniques, chronoamperometric oxidation, anodization, and low-temperature oxidation, were used to oxidize the surface of Ni30Co30Fe15Mn15Ti5Al5 High-Entropy Alloy. Surface studies, including the influence of the applied method on morphology and chemical composition, were carefully performed using a Scanning Electron Microscope equipped with Energy Dispersive Spectroscopy and X-ray Photoelectron Spectroscopy. To follow the trace of dissolved elements, the waste solutions were analyzed using Microwave Plasma Atomic Emission Spectroscopy. The expected increase in surface wettability after the oxidation process was observed. Oxidation in the furnace with constant air flow was the most efficient technique. The effectiveness of applied oxidation methods has not been described and compared in any published work.