Exploring failure modes of alumina scales on FeCrAl and FeNiCrAl alloys in a nitriding environment
Journal article, 2020

Two high-temperature FeCrAl and FeNiCrAl alloys were exposed in a strongly nitriding environment at 900 °C and the morphology of nitridation was studied. Quasi-in-situ experiments revealed that nitridation started at specific surface sites directly related to the alloy microstructure where the alumina scale was permeable to nitrogen. FeCrAl alloy grains with (112) orientation formed outward-growing alumina scales and were susceptible to nitridation. Outward-growing scales and substrate nitridation was also observed at chromium carbide precipitates in the FeNiCrAl alloy. Both alloys suffered nitridation at reactive element-rich (Y and Zr) inclusions larger than a certain critical size. The latter type of attack is caused by cracks and pores in the scale. The findings open new avenues of research for developing the next generation of high temperature alloys with superior properties.

Crystallographic orientation

High temperature oxidation

Alumina scale failure

Reactive elements

Nitridation

Author

A. N. Mortazavi

Harvard University

Mohsen Esmaily

Massachusetts Institute of Technology (MIT)

Christine Geers

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

N. Birbilis

Australian National University

Jan-Erik Svensson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Mats Halvarsson

Chalmers, Physics, Microstructure Physics

D. Chandrasekaran

Kanthal AB

Lars-Gunnar Johansson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Acta Materialia

1359-6454 (ISSN)

Vol. 201 131-146

Subject Categories

Manufacturing, Surface and Joining Technology

Metallurgy and Metallic Materials

Corrosion Engineering

DOI

10.1016/j.actamat.2020.09.058

More information

Latest update

10/22/2020