Improvement of isothermal oxidation resistance of a γ'-strengthened Co-Al-W-Mo-Ta-B alloy at 800℃via doping Ce

作者：Fei Zhong; Zhuo-Lin Tao; Jiang-Bo Sha

来源：Rare Metals, 2021, 40(08): 2065-2075.

Isothermal oxidation resistance,oxide scale evolution and failure mechanism of Ce-doped Co-Al-W-MoTa-B alloy(0.01 at%,0.05 at%,0.10 at% and 0.20 at% Ce)exposed at 800℃ were compared.The 0.01 Ce and 0.05 Ce alloys were consisted of γ/γ’ coherent micro structure,while the κ-Co3 W compound precipitated at the grain boundary of the 0.1 OCe and 0.20 Ce alloys in addition to the γ/γ’microstructure.The oxidation kinetics curves of the Cedoped alloys exhibited a parabolic time dependence on the weight gain.With an increasing nominal Ce content,the weight gain of the Co-Al-W-Mo-Ta-B alloys monotonically decreased.An oxide scale composed of a dense and uniform outer Co3 O4+CoO layer,a middle CoAl2 O4 and CoWO4 compound layer and an inner Al2 O3 layer.The excellent oxidation resistance of 0.2 Ce alloy was mainly attributed to a shorter incubation stage for the formation of the continuous and protective Al2 O3 layer and the thickest Al2 O3 layer during entire oxidation process.