Formation of corrosion pockets in FeNiCrAl at high temperatures investigated by 3D FIB-SEM tomography
Artikel i vetenskaplig tidskrift, 2020

A recently published study of high temperature nitridation of iron chromium aluminum alloys (FeCrAl) at 900 degrees C in N-2-H(2)has redundantly shown the formation of locally confined corrosion pockets reaching several microns into the alloy. These nitrided pockets form underneath chromia islands laterally surrounded by the otherwise protective alumina scale. Chromia renders a nitrogen-permeable defect under the given conditions and the presence of aluminum in the alloy. In light of these findings on FeCrAl, a focused ion beam-scanning electron microscope tomography study has been undertaken on an equally nitrided FeNiCrAl sample to characterize its nitridation corrosion features chemically and morphologically. The alloy is strengthened by a high number of chromium carbide precipitates, which are also preferential chromia formation sites. Besides the confirmation of the complete encapsulation of the corrosion pocket from the alloy by a closed and dense aluminum nitride rim, very large voids have been found in the said pockets. Furthermore, metallic particles comprising nickel and iron are deposited on top of the outer oxide scale above such void regions.

void formation

nitridation

FeNiCrAl

FIB-SEM tomography

Författare

Katrin Jahns

Univ Appl Sci Osnabruck

Ulrich Krupp

RWTH Aachen University

Gustav Sundell

Vitroprobe Analyt AB

Christine Geers

Chalmers, Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Materials and Corrosion - Werkstoffe und Korrosion

0043-2822 (ISSN) 1521-4176 (eISSN)

Vol. In Press

Ämneskategorier

Materialkemi

Metallurgi och metalliska material

Korrosionsteknik

DOI

10.1002/maco.201911386

Mer information

Senast uppdaterat

2020-08-29