High-temperature oxidation behavior of Nb–Si-based alloy with separate vanadium, tantalum, tungsten and zirconium addition

The microstructure and oxidation behavior of directionally solidified (DS) Nb–15Si–24Ti–4Cr–2Al–2Hf alloys with separate vanadium, tantalum, tungsten and zirconium additions were investigated by X-ray diffraction (XRD), electron probe microanalyzer (EPMA) equipped with wave-dispersive spectroscopy (...

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Bibliographic Details
Published in:Rare metals 2021-03, Vol.40 (3), p.607-615
Main Authors: Zhang, Sheng-Nan, Jia, Li-Na, Guo, Yue-Ling, Kong, Bin, Zhang, Feng-Xiang, Zhang, Hu
Format: Article
Language:English
Subjects:
Alloying effects
Alloying elements
Biomaterials
Chemistry and Materials Science
Directional solidification
Electron microscopy
Electron probes
Energy
High temperature
Materials Engineering
Materials Science
Metallic Materials
Microscopy
Nanoscale Science and Technology
Niobium oxides
Oxidation
Oxidation resistance
Physical Chemistry
Silicon base alloys
Silicon dioxide
Solid solutions
Spectroscopy
Spectrum analysis
Tantalum
Titanium dioxide
Tungsten
Vanadium
Wave diffraction
Wave dispersion
Zirconium
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Summary:The microstructure and oxidation behavior of directionally solidified (DS) Nb–15Si–24Ti–4Cr–2Al–2Hf alloys with separate vanadium, tantalum, tungsten and zirconium additions were investigated by X-ray diffraction (XRD), electron probe microanalyzer (EPMA) equipped with wave-dispersive spectroscopy (WDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) equipped with an energy-dispersive spectroscopy (EDS). Results show that the five alloys are all composed of primary (Nb,Ti) solid solution ((Nb,Ti) SS ) phase and eutectic (Nb,Ti) SS /(Nb,Ti) 5 Si 3 structure. After oxidation at 1250 °C for 100 h in air, the surfaces of the five alloys are covered by the oxides of Nb 2 O 5 , TiNb 2 O 7 , Ti 2 Nb 10 O 29 , TiO 2 and amorphous SiO 2 . It is found that the alloying elements of V and W are detrimental for oxidation resistance and the addition of Ta has no obvious effect. Zr addition obviously benefits the oxidation resistance at high temperature, by decreasing the weight gain from 242.75 to 184.83 mg·cm −2 . The oxidation mechanism of Nb–Si-based alloys and the effects of different alloying elements on the oxidation resistance of Nb–Si-based alloys were discussed.
ISSN:1001-0521
1867-7185
DOI:10.1007/s12598-017-0916-7