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Effect of boron on isothermal oxidation behavior of a nickel-base superalloy with high Al and Ti contents
Zhao, Guangdi; Zang, Ximin; Qi, Feng
2020-12-15
Source PublicationJOURNAL OF ALLOYS AND COMPOUNDS
Volume846
AbstractThe influence of boron on the oxidation resistance of conventionally cast U720Li alloy was investigated at 1130 degrees C and analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX) and electron probe microanalysis (EPMA). It has been found that the boron-undoped and -doped alloys all obey a super-parabolic rate law, but the oxidation rate is obviously increased by the boron addition. These alloys all show non-uniform oxidation between dendritic and interdendritic areas due to the serious microsegregation, while the oxide scale morphology of the high-boron alloy is quite different from that of the boron-undoped alloy. For boron-doped alloys, in the initial stage of oxidation the outward diffusion of boron from borides formed in the interdendritic region results in the formation of discontinuous and non-uniform B-rich oxide layers beneath and inside the Cr2O3 layer, while as the oxidation proceeds further boron can also transfer from the B-rich oxide to outer layers which eventually leads to disappearance of the B-rich oxide layers. The formation of B-rich oxide layers destroys the continuity of Cr2O3 layer and decomposition of B-rich oxide layers makes Cr2O3 layer more porous, which significantly reduce the protective property of the Cr2O3 layer and in turn decrease the oxidation resistance. Moreover, the eutectic (gamma + gamma') highly enriched in Ti, Al is prone to be oxidized and form a thicker scale than the other regions, and hence the significant increase of its precipitation with boron addition also contributes to increasing the oxidation rate. (C) 2020 Elsevier B.V. All rights reserved.
DOI10.1016/j.jallcom.2020.156490
WOS IDWOS:000567764900009
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Document Type期刊论文
Identifierhttp://ir.imr.ac.cn/handle/321006/82305
Collection中国科学院金属研究所
Recommended Citation
GB/T 7714
Zhao, Guangdi,Zang, Ximin,Qi, Feng. Effect of boron on isothermal oxidation behavior of a nickel-base superalloy with high Al and Ti contents[J]. JOURNAL OF ALLOYS AND COMPOUNDS,2020,846.
APA Zhao, Guangdi,Zang, Ximin,&Qi, Feng.(2020).Effect of boron on isothermal oxidation behavior of a nickel-base superalloy with high Al and Ti contents.JOURNAL OF ALLOYS AND COMPOUNDS,846.
MLA Zhao, Guangdi,et al."Effect of boron on isothermal oxidation behavior of a nickel-base superalloy with high Al and Ti contents".JOURNAL OF ALLOYS AND COMPOUNDS 846(2020).
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