OXIDATION BEHAVIOR OF AN IRON-CHROMIUM ALLOY CONTAINING YTTRIUM OR RARE-EARTH ELEMENTS BETWEEN 900 DEGREES AND 1200 DEGREES C

The oxidation behavior of an Iron-15 wt pct Chromium alloy, some containing small additions of yttrium or rare earth elements, have been observed using a TG and an EPMA method at temperatures between 900° and 1200°C. Yttrium or rare earth element additions to the Iron-Chromium alloy result in a rapid initial oxidation rate, but decrease the total weight gain of the Iron-Chromium alloy at the final time of exposure. The line trace obtained indicates that the increased segregation of chromium content in the inner oxide layer of the alloy containing yttrium or rare earth elements and also shows that the enriched concentration of yttrium or lanthanum is detected within the chromium oxides which exist near the oxide scale/alloy matrix interface. Yttrium or rare earth element oxides serve as the sites for the protective chromium oxide scales. © 1974, American Society for Metals, The Melallurgical Society of AIME.