Beyond the sulfur effect
- Lawrence Berkeley National Lab., CA (United States). Materials Science Div.
The addition of reactive elements (REs) is known to increase the adherence of Al{sub 2}O{sub 3} scales and the underlying alloys. A widely accepted mechanism is that the REs getter the sulfur impurity in the alloy, thus preventing it from segregating to the scale-alloy interface to weaken the interfacial bonding. This paper provides evidence showing that not all S-free interfaces are strong. Although eliminating the sulfur in the alloy can greatly improve scale adhesion, the presence of RE clearly has additional beneficial effects that make the scale-alloy interface even stronger. Fe{sub 3}Al-base alloys, with or without Zr additions or a desulfurization H{sub 2}-anneal were oxidized at 1000 C in O{sub 2}. The amount of sulfur at the Al{sub 2}O{sub 3}-alloy interface was studied after the scales were removed by scratching with a diamond stylus in ultra-high vacuum using Auger spectroscopy. The interface composition was related to the spallation resistance of the scale.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 679205
- Journal Information:
- Oxidation of Metals, Vol. 52, Issue 3-4; Other Information: PBD: Oct 1999
- Country of Publication:
- United States
- Language:
- English
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