Carburization behavior of FeCrAl alloy APMT and the critical role of pre-oxidation

• Published in: Corrosion science Vol. 224; p. 111520
• Main Authors: Kosmidou, Maria, Nizolek, Thomas J., Rizk, Jason T., Hyosim, Kim, Luther, Erik P., Schroeder, Anthony, Van Wyk, Jurie, Matthews, Christopher, Kardoulaki, Erofili
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.11.2023; Elsevier
• Subjects: Alumina; Carburization; FeCrAl alloy - APMT; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; MATERIALS SCIENCE; Oxidation; TEM analysis; Thermodynamic diagrams; Thermodynamic diagrams; Oxidation; TEM analysis; Alumina; FeCrAl alloy - APMT; Carburization
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2023.111520

The carburization behavior of bare and pre-oxidized APMT has been assessed after long-term graphite exposure at 1000 °C. Bare coupons formed a thick scale after graphite exposure due to carbon interaction and chromium-rich carbides were detected, as predicted from thermodynamic calculations. Pre-oxidation of APMT was conducted in air, and oxidation kinetics were measured through thermogravimetry. The oxide layer formed at 800 °C failed to prevent carburization. However, increasing the pre-oxidation temperature to 1200 °C produced an oxide layer with good resistance to carbon diffusion indicating that the alpha-alumina formed at high temperatures is key in preventing carburization of the material. [Display omitted] •Carbide formation (Cr23C6) increased with exposure time on bare APMT samples.•CALPHAD calculations confirmed the carbide formation in FeCrAl.•Pre-oxidation of APMT conducted in air at 800 °C failed to prevent carburization and carbide formation occurred in the bulk.•Pre-oxidation of APMT at 1200 °C produced an oxide layer with good resistance to carbon diffusion, thus protecting the sample from carburization.