Abstract Scope |
Oxidation behavior of AlCoCrFeNi HEA depends on its constituent elements, their varying content, FCC/BCC/B2/Sigma phase fractions. It has been observed that the as-cast AlCoCrFeNi microstructure comprises Fe-Cr-rich BCC + Al-Ni-rich B2. On exposure to heat, FCC, Sigma, and various other phases are formed. In our present work, we have first stabilized the phase constitution of the base alloy to Ni-Al rich B2 + Fe-Co-rich FCC by subjecting the as-cast pellet to an annealing treatment in a vacuum atmosphere at 1150C for 5h. This stabilized simple B2+FCC microstructure is introduced to isothermal continuous oxidation at 1150C. A stable, adherent, alpha-alumina oxide layer is achieved in just 3 minutes of exposure which grows to protect the underlying base alloy from further oxidation. The specific weight gain rate is remarkably low. Characterization tools like STEM, TEM, SEM, EBSD, XRD, TGA, and DSC have been deployed to study the oxidation behavior. |