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Oxidation resistance study of alloys

APT, scale on a crofer alloy
Atom probe tomography of the Cr²O³ scale on a Crofer alloy used in solid oxide fuel cells

Ferritic alloys of the Crofer family work as interconnects for solid oxide fuel/electrolysis cells. A complex chromia-based oxide scale growing on their surface protects the interconnects from degradation under service conditions. The Atom Probe Tomography (APT) image shows a nanograined structure of the chromia layer formed at 800C in a model Ar-20%O² atmosphere. APT reveals Nb segregation zones at grain boundaries (greater than 0.4% Nibium inside the isoconcentration surface) and explains the deleterious Nb effect on the oxidation resistance. Local Mn accumulations inside chromia grains entail the later nucleation of the MnCr²O4 spinel.

Recorded on CAMECA LEAP 4000X HR at Forschungszentrum Jülich, Jülich, Germany.
Image courtesy of I. Povstugar.

Winning image for the month of  May 2020