Abstract
High entropy alloys (HEAs) are a newly developed family of multi-component alloys composed of at least five major elements, such as chromium, iron, nickel, aluminum, cobalt, titanium, copper, as well as molybdenum, etc. HEAs Co1.5CrFeNi1.5Ti0.5 has an FCC structure, a higher hardness than other FCC, good resistances to oxidation, and atmospheric corrosion. The potential applications of the HEAs are very significant. On the other hand, the addition of Mo, such as 304ss and 316ss, may have good pitting corrosion resistance. To further understand the electrochemical properties of the HEAs, the HEAs Co1.5CrFeNi1.5Ti0.5Mox was conducted in 0.5 M H2SO4 and 0.1 M NaCl solution. The result of this study shows that the HEAs Co1.5CrFeNi1.5Ti0.5Mox have much higher pitting corrosion resistances (~1.2 V) than 304ss (~0.18 V) in the Cl- containing environments, as indicated by the significant differences in passive range as well as in pitting potential. The anodic polarization curves determined for Co1.5CrFeNi1.5Ti0.5Mox and for 304ss are very similar to each other in the chloride-free 0.5M H2SO4. However, the SEM images show that the surface morphology of the HEAs has been seriously damaged due to their cast-structure. The corrosion phenomenon will be discussed via electrochemical impedance spectroscopy together with the SEM observations. The HEAs which was set in 1100 ℃ for 6 hours, then quenched by water is called homogenization. This kind of HEAs has good corrosion resistance in sulfuric acid solution. The oxidation film of HEAs was too thick. It was under the 900℃environment which was filled with oxygen for 4 hours treatment. The improvement way is to shorten the oxidation time or transform the atmosphere. In order to form an good adhesion and thin film.