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

Various silicon containing Fe-Mn-Al alloys were studied to estimate th e influence of the silicon content on their oxidation behaviour. Silic on has a beneficial effect. Diffusion properties seem to be modified i n 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 th e 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 improveme nt in corrosion resistance of the silicon free alloy was observed afte r dipping in a cerium containing sol. This result is in accordance wit h 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.