Synergistic effect of Y and Nb on the high temperature oxidation resistance of high Nb containing TiAl alloys

Liu, Xiang; Zhao, Liming; Wang, Y.L.; Zhang, L.Q.; Lin, Jianwei

doi:10.1016/j.intermet.2012.01.015

Cited by 43 publications

(15 citation statements)

References 11 publications

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“…Therefore, the globular oxide structure consisted of a core Y 2 O 3 particle and multi-layered TiO 2 /Al 2 O 3 -rich/TiO 2 -rich shells from the inside to outside. This kind of oxides protruding into the substrate could improve the adhesion of scale 25 , 26 . It should be noted that transient or incomplete core-shell globular oxidation could also be observed, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Yttrium exhibits a strong grain refinement effect, thus improving the tensile strength of TiAl-based alloys 23 , 24 . The addition of yttrium also significantly improves oxidation resistance due to its strong affinity to oxygen 20 , 23 , 25 , 26 . Oxide pegs protruding into the substrate 26 and convex-shaped nail-like oxides 25 were observed at the scale-substrate interface, which play an important role in anchoring the oxide scale and improving anti-spalling ability of the scale on the surface of titanium aluminide alloys with an addition of yttrium.…”

Section: Introductionmentioning

confidence: 99%

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Core-multishell globular oxidation in a new TiAlNbCr alloy at high temperatures

Shougao

et al. 2017

Sci Rep

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Oxidation resistance is one of key properties of titanium aluminide (TiAl) based alloys for high-temperature applications such as in advanced aero-engines and gas turbines. A new TiAlNbCr alloy with micro-addition of yttrium has been developed, but its oxidation behavior is unknown. To provide some fundamental insights, high-temperature oxidation characteristics of this alloy are examined via scanning electron microscopy, transmission electron microscopy, electron probe microanalysis, and X-ray diffraction. We show that distinctive core-multishell globular oxidation and “daisy” flower-like oxidation occur exclusively around Y2O3 particles. Globular oxides exhibit multi-layered Y2O3/TiO2/Al2O3-rich/TiO2-rich shell structures from the inside to outside. Flower-like inner oxides consist of core Y2O3 particles surrounded by divergent Al2O3 and oxygen-rich α2-Ti3Al in the near-scale substrate. As the scale-substrate interface moves inward, the inner oxide structures suffer deeper oxidation and transform into the globular oxide structures. Our results demonstrate that the unique oxidation characteristics and the understanding of formation mechanisms pave the way for the exploration and development of advanced oxidation-resistant TiAl-based materials.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Core-multishell globular oxidation in a new TiAlNbCr alloy at high temperatures

Shougao

et al. 2017

Sci Rep

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“…A great deal of research work has been undertaken to improve the oxidation behavior of these alloys by adding ternary and quaternary elements. Our recent work reveals that an appropriate amount of Y addition (depend on Nb) is effective in improving the oxidation resistance, especially high temperature long term oxidation resistance (lOOOhrs and 1000 cycles) by refining the oxide particles, promoting formation of a protective continuous AI2O3 scale and improving the adherence of the oxide scale and matrix the interlayer adhesion [26][27]. High Nb addition greatly improves the oxidation resistance of TiAl alloys.…”

Section: Oxidation Resistance and Mechanical Propertiesmentioning

confidence: 98%

Alloy Design Concepts for Wrought High Temperature TiAl Alloys

Lin

Zhang

et al. 2014

Gamma Titanium Aluminide Alloys 2014

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Wrought TiAl alloys provide more possibility to control the microstructure and give a balanced mechanical properties than cast alloy. Titanium aluminides based on the general composition Ti-45Al-(6-9)Nb (in at.%) exhibit several desired properties for higher temperature applications. N b addition changes the Ti-Al phase diagram and the segregations of N b and other elements are easy to form, which induces formation of B2 phase. B2 phase worsens the mechanical properties at both room temperature and elevated temperatures. The new idea is that the P phase is can be used to improve the hot-workability, and the segregations can be lightened during the deformation and finally disappeared, so stable B2 phase is avoided at room temperature. Otherwise, high Nb addition significantly reduces the stalking fault energy (SFE), resulting in abundant twinning and twin intersections, which plays an important role for accommodating heterogeneous deformation and avoiding formation of microcrack at boundaries. The basic compositional characteristics of the high temperature TiAl alloys are high Nb and low A1 content, typically 6/9 N b and 44-46A1. Carefully microalloying using the elements B, W, Y , C may further optimize the properties of the alloys. These wrought alloys have excellent oxidation resistance, balanced mechanical properties and good workability.

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“…Hence, the residual stress between the oxide scale and substrate may be removed [181]. e beneficial effect of Y on the scale spallation of TiAl alloys is attributed to proposed mechanisms such as [181][182][183] (1) e reactive-element-oxide particles encourage mechanical keying of the oxide scale on the substrate (2) e reactive elements tend to serve as vacancy sink sites resulting in the suppression of vacancy coalescence at the alloy-oxide interface for void formation (3) e segregation of Y at the oxide grain boundaries blocks diffusion paths and thus decreases growth stress in the scale (4) e formation of a fine-grain layer structure improves the plasticity of the oxide scale Another concept used in improving the oxidation resistance of TiAl alloys includes the incorporation of halogens (F, Cl, Br, and I) termed as the halogen effect. e addition of halogens has been investigated and concluded to support selective Al transport and improve adhesion between the formed Al 2 O 3 scale and the metal surface.…”

Section: Influence Of Ternary Elements On Oxidation Resistancementioning

confidence: 99%

Solid-State Processing Route, Mechanical Behaviour, and Oxidation Resistance of TiAl Alloys

Cobbinah

Matizamhuka

2019

Advances in Materials Science and Engineering

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A primary challenge associated with TiAl alloys is their low ductility at room temperature. One approach to overcome this flaw is attaining ultrafine grains in the alloy’s final microstructure. The powder metallurgy (PM) processing route favours the synthesising of ultrafine grains in TiAl alloys. This paper features the mechanical alloying (MA) process and rapid consolidation through the spark plasma sintering (SPS) technique, which comprises the PM process. Furthermore, a second approach discussed covers microalloying TiAl alloys. An evaluation of the influence of high oxygen content is also presented, including the formation of α-Al2O3. A section of the review delves into the dynamic recrystallisation mechanisms involved in elevated temperature deformation of TiAl alloys. The final section highlights the efficacy of ternary element additions to TiAl alloys against oxidation.

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Synergistic effect of Y and Nb on the high temperature oxidation resistance of high Nb containing TiAl alloys

Cited by 43 publications

References 11 publications

Core-multishell globular oxidation in a new TiAlNbCr alloy at high temperatures

Core-multishell globular oxidation in a new TiAlNbCr alloy at high temperatures

Alloy Design Concepts for Wrought High Temperature TiAl Alloys

Solid-State Processing Route, Mechanical Behaviour, and Oxidation Resistance of TiAl Alloys

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