INFLUENCE OF MINOR ADDITIONS TO FE-MN-AL ALLOYS IN AN OXIDIZING ENVIRONMENT - ROLE OF A CERIUM OXIDE MODIFIED SURFACE ON SILICON-CONTAINING ALLOYS

Various silicon containing Fe-Mn-Al alloys were studied to estimate the influence of the silicon content on their oxidation behaviour. Silicon has a beneficial effect. Diffusion properties seem to be modified in the alumina scale grown at the scale substrate interface. Then, both scale growth and adherence are strongly affected. One possibility for modifying scale growth properties without changing the strength of the base alloy involves surface additions. The oxidation behaviour of a CeO2 surface modified Fe-Mn-Al-(Si) alloy was studied at 850-degrees-C in pure oxygen for exposure times up to 70 h. A significant improvement in corrosion resistance of the silicon free alloy was observed after dipping in a cerium containing sol. This result is in accordance with the classical beneficial effect of ''active elements''. On the other hand, cerium deposition on a silicon containing Fe-Mn-Al alloy leads to an opposite result. The inhibition of the beneficial silicon effect by cerium additions will be discussed.