Oxidation Resistance and Effects of the Heat Treatment under Low Partial Pressure Oxygen Atmosphere in Intermetallic Compound TiAl Containing Nb

Yoshihara, Michiko; Imamura, Naochika; Kobayashi, Equo; Miura, K.; Mishima, Yoshinao; Suzuki, Tomoo; Tanaka, Ryôhei

doi:10.2320/jinstmet1952.57.5_574

Cited by 24 publications

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“…Figure 8 shows the relationship between the Nb content, x, and the oxide layer thickness, l. As shown in the figure, the oxide thickness decreased with an increase in Nb content, from 0 to around 13³15 mol%Nb, and then the layer thickness increased with an increase in Nb content. Yoshihara et al 19) have investigated the effects of Nb addition on the high-temperature oxidation resistance of TiAlNb alloys, and reported that the layer thickness decreases with increasing Nb content, with up to 15 mol%Nb added, that is, the oxidation resistance was improved by Nb addition. The results from this study regarding oxide growth suppression effects of Nb addition at 13³15 mol%Nb or less in TiNb alloys are in good agreement with results reported by Yoshihara et al The Nb content at which the layer thickening begins, almost coincides with the composition at which the phase separation of the oxide phase and densification of the microstructure start, suggesting that the phase separation by the addition of a certain amount of Nb is also related to the oxide growth rate.…”

Section: Effect Of Nb Addition On Oxide Formation On Tixnb Alloysmentioning

confidence: 99%

“…Regarding effect of Nb addition on Ti oxide formed in TiAlNb alloys at high-temperature, Yoshihara et al reported that Nb was first dissolved in TiO 2 , and then TiO 2 and Nb 2 O 5 were formed when Nb content exceeded the solid solubility limit in TiO 2 . 19) According to the TiO 2 Nb 2 O 5 phase diagram, 24) the solubility limit of Nb 2 O 5 in TiO 2 was TiO 2 = 28.5 mol% and Nb 2 O 5 = 2.1 mol% at 1273 K. When Nb content in the oxide exceeds the solubility limit, phase separation from TiO 2 to TiO 2 and TiNb 2 O 7 occurs. Thus, the atomic ratio of Ti and Nb is Ti:Nb = 87:13.…”

Section: Phase Separation Of Titanium Oxide By Nb Additionmentioning

confidence: 99%

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Effect of Nb Addition on Oxide Formation on Ti–xNb Alloys

Ogawa

Miura-Fujiwara

2019

Mater. Trans.

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It had been reported that Ti29Nb13Ta4.6Zr (TNTZ) alloy forms a dense oxide layer by high-temperature oxidation whereas CP Ti forms a multilayered oxide consisted of rutile monolayers and void layer. This morphological change is supposed to be mainly caused by Nb addition in Ti since the dense oxide layer of TNTZ consists of multiple oxide phases, at least with rutile TiO 2 and TiNb 2 O 7 . In this study, hightemperature oxidation at 1273 K for 3.6 ks in the air of TixNb alloys (x = 1, 5, 7, 10, 13, 15, 18, 20, 23, 26, 28, 30 and 32 mol%) was investigated to discuss the effect of Nb addition to Ti on its high-oxidation behavior, and on its oxide microstructure. From the results of the SEM observation, an oxide layer with a void layer was formed on TixNb substrate from 1 mol%Nb up to 10 mol%Nb. However, densification of the oxide layer was confirmed at Ti13Nb. Then, the dense oxide layer was formed up to 32 mol%Nb. XRD results indicated that only rutile-type TiO 2 was identified from 1 mol%Nb up to 10 mol%Nb, then both TiO 2 and TiNb 2 O 7 were formed from 13 mol%Nb to 32 mol%Nb. These results indicate that dense oxide layer formation attributes to phase separation from TiO 2 to TiNb 2 O 7 . Until 10 mol%Nb, the thickness of oxide layer was suppressed by Nb addition, whereas the layer thickness increased with increasing Nb content from 13 mol%Nb. The maximum exfoliation resistance of the oxide layer was obtained at 20 mol%Nb. The results of oxide growth rate at each TixNb alloys suggested that Nb diffusion in Ti may rate-determining process of the dense oxide layer formation. [

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Section: Effect Of Nb Addition On Oxide Formation On Tixnb Alloysmentioning

confidence: 99%

Section: Phase Separation Of Titanium Oxide By Nb Additionmentioning

confidence: 99%

Effect of Nb Addition on Oxide Formation on Ti–xNb Alloys

Ogawa

Miura-Fujiwara

2019

Mater. Trans.

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“…4 from the cylindrical ingot. The specimen surface was polished with abrasive paper #400 and then cleaned ultrasonically in a methanol and benzene solution.…”

Section: Alloy Preparationmentioning

confidence: 99%

“…To improve the anti-oxidation properties of g-TiAl alloys a variety of methods have been proposed such as third element addition [1,2], pre-oxidation at low oxygen partial pressures [3,4], pack cementation [5][6][7], ion implantation [8], sulfidation processing [9][10][11][12], two-step Cr and Al pack cementation [13], and others [14,15]. When coated g-TiAl alloys were oxidized for long periods, however, the formation of non-protective scales resulted in rapid degradation.…”

Section: Introductionmentioning

confidence: 99%

Superior long-term oxidation resistance of Ni–Al coated TiAl alloys

2005

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“…Therefore, Nb, which is the most abundant solid solution element in the Ti alloy, has also a solid solution limit of about 13 mol% in TiO 2 , so that a part of Nb is dissolved in TiO 2 and the excess Nb precipitates as TiNb 2 O 7 . It has been reported that the addition of Nb to Ti up to 10 mol% decreases the high-temperature oxidation rate [10,11]. It is suggested that the slow diffusion rate of Nb relative to Ti and the oxidation reaction to TiO 2 and TiNb 2 O 7 controlled the reaction at the interface, and the atomic diffusion and the oxidation reaction rate were consequently balanced.…”

Section: Metal/oxide Interface Of Tntzmentioning

confidence: 99%

Effect of Nb addition on high-temperature oxidation behavior, oxide layer structure, and its exfoliation resistance of Ti-Nb Alloys

et al. 2020

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The authors proposed an oxide coating on Ti alloys for the dental abutment tooth, and they had reported that Ti–29Nb–13Ta–4.6Zr (TNTZ) alloy forms a dense oxide layer by high-temperature oxidation. On the other hand, CP Ti forms a multilayered oxide consisted of rutile monolayers and the void layer. This morphological change by alloying is supposed to be mainly caused by Nb addition in Ti since the dense oxide layer of TNTZ mainly consists of rutile TiO2 and TiNb2O7. Therefore, in this study, oxidation behaviors of various range of Nb content of Ti-xNb alloys (x = 1 ~ 32 mol%) were investigated, and exfoliation resistance was evaluated. And in this paper, the oxide/metal interfacial microstructure of oxidized CP Ti, TNTZ alloy, and Ti-Nb alloy was studied by a transmission electron microscopy (TEM) and by a scanning transmission electron microscopy with an electron dispersive spectroscopy (STEM-EDS). The cross-sectional observations suggested that the substrate was gradually oxidized during heat treatment, and nucleation and grain growth of TiO2 and TiNb2O7 proceed at the metal/oxide interface. Consequently, the gradual oxidation process in TNTZ and Ti-Nb alloys could lead to its continuous interfacial microstructure and dense oxide structure, which can achieve high exfoliation resistance.

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Oxidation Resistance and Effects of the Heat Treatment under Low Partial Pressure Oxygen Atmosphere in Intermetallic Compound TiAl Containing Nb

Cited by 24 publications

References 0 publications

Effect of Nb Addition on Oxide Formation on Ti–xNb Alloys

Effect of Nb Addition on Oxide Formation on Ti–xNb Alloys

Superior long-term oxidation resistance of Ni–Al coated TiAl alloys

Effect of Nb addition on high-temperature oxidation behavior, oxide layer structure, and its exfoliation resistance of Ti-Nb Alloys

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