The effect of yttrium on oxide scale growth on Co-Al-W-based superalloys

• Published in: Corrosion science Vol. 208; p. 110674
• Main Authors: Migas, Damian, Chmiela, Bartosz, Myalska-Głowacka, Hanna, Moskal, Grzegorz, Matus, Krzysztof, Swadźba, Radosław
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2022
• Subjects: Oxidation; Reactive elements effect; Superalloys; Yttrium; γ–γ′ cobalt-based superalloys; Reactive elements effect; Oxidation; Superalloys; Yttrium; γ–γ′ cobalt-based superalloys
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2022.110674

The study on the individual role of yttrium (Y) and Y-related phases during scale formation on Co-9Al-9 W (at%) and other Co-based alloys during isothermal and cyclic oxidation at 900 °C was performed. The addition of Y increased the oxidation resistance of Co-(Ni)-Al-W alloys, especially under cyclic conditions due to an oxide keying effect related to the internal oxidation of Y-containing phase constituents. The Y-containing oxide areas corresponded in number, size, shape, and spatial distribution to the original Y-rich particles in the alloy. The mechanism describing the formation of Y-related oxides within the oxide scale was proposed.
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•Improvement of oxidation resistance of Co-Al-W-based alloys by Y-addition.•Formation of Y-rich oxide inclusions connected with the “keying” effect.•Preferential oxidation of Y-containing alloys via Y-rich intermetallic phases.•Oxidation of Y contained in YCo5 to Y2O3 in the internal oxidation zone and formation of Y2WO6 in the middle oxide zone.•Heritage of oxide inclusions morphology from Y-rich intermetallic phases.