Chromium-molybdenum-aluminum alloys with oxidation-resistance imparted by thermal pre-treatment
AssigneeWisconsin Alumni Research Foundation
InventorsDan THOMA, Michael NIEZGODA
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Abstract
Ternary chromium-molybdenum-aluminum (CrMoAl) alloys that form oxidation-resistant surface films for high-temperature applications are provided. Also provided are methods for thermally pre-treating the alloys to form the oxidation resistant surface films. The surface films have a stratified structure that includes an exterior surface oxide layer comprising chromium oxides and aluminum oxides and an interior aluminum nitride-rich region comprising aluminum nitride precipitates dispersed in a CrMoAl alloy matrix. The interior aluminum nitride precipitates act as oxygen sinks to sequester oxygen diffusing inward into the CrMoAl to prevent further oxidation of the underlying bulk alloy.
Claims18
An oxidation-resistant chromium-molybdenum-aluminum alloy comprising:
- a base layer of a ternary chromium-molybdenum-aluminum alloy;
- a nitride-rich layer over the base layer, the nitride-rich layer comprising aluminum nitride precipitates dispersed in a chromium-molybdenum-aluminum alloy matrix;
- an oxide-rich layer over the nitride-rich layer, the oxide-rich layer comprising aluminum oxide precipitates dispersed in a chromium-molybdenum-aluminum alloy matrix;
- and
- a chromia-rich surface oxide layer over the oxide-rich layer, the chromia-rich surface oxide layer comprising chromium oxides and aluminum oxides.
A coated substrate comprising:
- a substrate having a surface;
- and
- a coating of an oxidation-resistant chromium-molybdenum-aluminum alloy on the surface of the substrate, the coating comprising:
- a base layer of a ternary chromium-molybdenum-aluminum alloy;
- a nitride-rich layer over the base layer, the nitride-rich layer comprising aluminum nitride precipitates dispersed in a chromium-molybdenum-aluminum alloy matrix;
- an oxide-rich layer over the nitride-rich layer, the oxide-rich layer comprising aluminum oxide precipitates dispersed in a chromium-molybdenum-aluminum alloy matrix;
- and
- a chromia-rich surface oxide layer over the oxide-rich layer, the chromia-rich surface oxide layer comprising chromium oxides and aluminum oxides.
Dependencies are inferred from the claim text.