High-Temperature Oxidation Behavior of Base Material and Laser-weld Specimens of a Thin FeCrAl-RE Foil at around 900°C

El Kadiri, H., Molins, R., Bienvenu, Y., & Horstemeyer, M. (2004). High-Temperature Oxidation Behavior of Base Material and Laser-weld Specimens of a Thin FeCrAl-RE Foil at around 900°C. Materials Science Forum. Les Embiez, France: Trans Tech Publications Ltd, Zurich-Ueticon, CH-8707, Switzerland. 461, 1157-1164.

Abstract

Isothermal oxidation of laser welded FeCrAl-RE samples containing specific fractions of seams in a bead-on-plate "configuration" has been performed at around 900°C and studied using TGA, SEM, TEM and EPMA techniques. An important reduction in the alumina-growth rate on the fusion zone occurs at 900°C, thereby, suppressing the discontinuous increase in mass gain commonly observed during the high temperature oxidation of alumina-forming alloys. This phenomenon is mainly related to the concomitant dramatic chromium carbide precipitation at the fusion zone/scale interface and possible earlier injection of the rare earth elements into the scale. The former, which is linked to the laser melting-induced high free carbon, contributes to the increase in effectiveness of the diffusion barrier provided by the thermally growing scale. The latter is correlated with the initial high Ce+La enrichment at the fusion zone surfaces and is manifested by the elimination of detrimental platelet transformation during the initial stages of oxidation.