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This content will become publicly available on December 1, 2023

Title: Unraveling the role of tungsten as a minor alloying element in the oxidation NiCr alloys
Abstract Ni-based superalloys offer a unique combination of mechanical properties, corrosion resistance and high temperature performance. Near ambient pressure X-ray photoelectron spectroscopy was used to study in operando the initial steps of oxidation for Ni-5Cr, Ni-15Cr, Ni-30Cr and Ni-15Cr-6W at 500 °C, p(O 2 )=10 −6 mbar. The comparison of oxide evolution for these alloys quantifies the outsized impact of W in promoting chromia formation. For the binary alloys an increase in chromia due to Cr-surface enrichment is followed by NiO nucleation and growth thus seeding a dual-layer structure. The addition of W (Ni-15Cr-6W) shifts the reaction pathways towards chromia thus enhancing oxide quality. Density functional theory calculations confirm that W atoms adjacent to Cr create highly favorable oxygen adsorption sites. The addition of W supercharges the reactivity of Cr with oxygen essentially funneling oxygen atoms into Cr sites. The experimental results are discussed in the context of surface composition, chemistry, reactant fluxes, and microstructure.
Authors:
; ; ; ; ;
Award ID(s):
2004326
Publication Date:
NSF-PAR ID:
10341108
Journal Name:
npj Materials Degradation
Volume:
6
Issue:
1
ISSN:
2397-2106
Sponsoring Org:
National Science Foundation
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