Microstructural Investigation of the Initial Oxidation of the FeCrAlRE Alloy Kanthal AF in Dry and Wet O-2 at 600 and 800 degrees C
Journal article, 2010

The FeCrAlRE (where RE is reactive element) alloy Kanthal AF was exposed isothermally at 600 and 800 degrees C for 72 h in dry O-2 and in O-2 with 10 vol % H2O. The mass gains were 3-5 times higher at the higher temperature. The presence of water vapor increased the oxidation rate at 800 degrees C, while no significant effect was observed at 600 degrees C. A thin two-layered oxide formed at 600 degrees C: an outer (Fe, Cr)(2)O-3 corundum-type oxide, containing some Al, and an inner, probably amorphous, Al-rich oxide. At 800 degrees C a two-layered oxide formed in both environments. The inner layer consisted of inward grown alpha-Al2O3. In dry O-2 the originally formed outward grown gamma-Al2O3 had transformed to alpha-Al2O3 after 72 h. Water vapor stabilized the outward grown gamma-Al2O3 and hence no transformation occurred after 72 h in humid environment. RE-rich oxide particles with varying composition (Y, Zr, and Ti) were distributed in the base oxide at both temperatures and in both environments. The RE-rich particles were separated from the alloy substrate by a layer of Al-rich oxide. At 800 degrees C the Y-rich RE particles were surrounded by thick oxide patches in both dry and humid O-2.

40-percent h2o

900 degrees-c

mg-incorporation

oxide scales

water-vapor

alumina scales

cyclic oxidation

fecraire alloys

high-temperature oxidation

growth

Author

Sead Canovic

Chalmers, Applied Physics, Microscopy and Microanalysis

Josefin Engkvist

Dalarna university

Fang Liu

Chalmers, Applied Physics, Microscopy and Microanalysis

Haiping Lai

Chalmers, Applied Physics, Microscopy and Microanalysis

Helena Götlind

Environmental Inorganic Chemistry 1

Kristina M Hellström

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Jan-Erik Svensson

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Lars-Gunnar Johansson

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

M. Olsson

Dalarna university

Mats Halvarsson

Chalmers, Applied Physics, Microscopy and Microanalysis

Journal of the Electrochemical Society

0013-4651 (ISSN) 1945-7111 (eISSN)

Vol. 157 6 C223-C230

Subject Categories

Inorganic Chemistry

Chemical Engineering

DOI

10.1149/1.3391447

More information

Latest update

11/3/2020