Transport mechanisms during the high-temperature oxidation of ternary γ/γ′ Co-base model alloys

Weiser M, Chater RJ, Shollock BA, Virtanen S (2019)

Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2019

Journal

npj Materials Degradation Nature Research

Book Volume: 3

Pages Range: 1-11

Article Number: 33

DOI: 10.1038/s41529-019-0096-z

Open Access Link: https://doi.org/10.1038/s41529-019-0096-z

Abstract

Over a decade ago, γ′-strengthened Co-base alloys were introduced as potential replacement for conventional Ni-base Superalloys. Insufficient resistance against high-temperature oxidation restricts the number of possible applications. The present study contributes to the understanding of elementary mechanisms such as material transport during extensive oxide scale formation on γ/γ′ Co-base alloys to explain their inferior oxidation behaviour. A clear dependency of the scale growth kinetics on W content and oxidation temperature is demonstrated by thermogravimetry and subsequent analysis of cross-sections. By means of electron backscattered diffraction (EBSD), the evolution of microstructures in the outer oxide layers were examined depending on the oxidation temperature. Sequential exposure of samples in 16O2- and 18O2-containing atmospheres proved counter-current material transport. The combination of focused ion beam (FIB) and secondary ion mass spectroscopy (SIMS) visualised the formation of new oxide phases mainly on the outer and inner interface of the oxide scale. An elaborate review of available transport paths for oxygen is given during the discussion of results. All experimental findings were combined to a coherent explanation of the inferior oxidation resistance of this relatively new class of high-temperature materials at temperatures above 800 °C.

Authors with CRIS profile

Martin Weiser Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften) Sannakaisa Virtanen Professur für Werkstoffwissenschaften (Korrosion und Oberflächentechnik)

Involved external institutions

Imperial College London / The Imperial College of Science, Technology and Medicine GB United Kingdom (GB) King’s College London GB United Kingdom (GB)

How to cite

APA:

Weiser, M., Chater, R.J., Shollock, B.A., & Virtanen, S. (2019). Transport mechanisms during the high-temperature oxidation of ternary γ/γ′ Co-base model alloys. npj Materials Degradation, 3, 1-11. https://dx.doi.org/10.1038/s41529-019-0096-z

MLA:

Weiser, Martin, et al. "Transport mechanisms during the high-temperature oxidation of ternary γ/γ′ Co-base model alloys." npj Materials Degradation 3 (2019): 1-11.

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