Absorption and diffusion of oxygen in the Ti3Al alloy

Бакулин, А. В.; Latyshev, A. M.; Kulkova, S. E.

doi:10.1134/s1063776117070019

Cited by 24 publications

(19 citation statements)

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“…As regards ground states properties of the Ti 3 Al system (elastic constants, electronic density-of-states and band structure, not shown here for simplification purposes), the present simulations reproduced exactly the results of Bakulin et al [40] and [41]. These works used the same approach, i.e.…”

Section: Ground State Properties Of Thesupporting

confidence: 85%

“…To study the hydrogen insertion, a quick analysis of interstitial sites inside the Ti 3 Al-D0 19 system is necessary. Part of the work conducted by Bakulin et al [40], in their study on oxygen insertion, can be used here. They identified four insertion sites, labeled O1, O2, T1 and T2.…”

Section: Hydrogen Solubilitymentioning

confidence: 99%

“…2a and 6g) sites. A correlation can now be made between the notations of Bakulin [40] and crystallographic notations: O1 = 2a, O2 = 6g and 12k = T 1, 4 f = T 2. The other sites are located on the faces or the edges of the octahedron or tetrahedron volumes.…”

Section: Hydrogen Solubilitymentioning

confidence: 99%

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Theoretical study of the insertion and diffusivity of hydrogen in the Ti3Al-D019 system: Comparison with Ti-hcp and TiAl-L10 systems

Connétable

2019

International Journal of Hydrogen Energy

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Using first-principles calculations, the insertion and diffusivity of hydrogen in the Ti 3 Al-D0 19 system are presented and discussed. After a brief description of the properties of Ti 3 Al, the different sites of insertion are identified and discussed. The octahedral configuration surrounded by Ti atoms only (2a Wyckoff position) is found to be the preferred insertion site for H atoms. The second octahedral and the two tetrahedral sites are found significantly less stable than 2a sites. Phonon, electronic and elastic properties were computed to analyze the interactions between hydrogen and the metal. Results show that hydrogen atoms interact little with the metal. The insertion into a 2a site minimizes the elastic deformation and electronic transfer of surrounding atoms. The diffusion coefficient of hydrogen is then calculated and discussed by using DFT simulations, kinetic Monte-Carlo simulations and a multi-site approach. These results are compared with those of H diffusion into the Ti-hcp and TiAl-L1 0 systems.

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Section: Ground State Properties Of Thesupporting

confidence: 85%

Section: Hydrogen Solubilitymentioning

confidence: 99%

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Theoretical study of the insertion and diffusivity of hydrogen in the Ti3Al-D019 system: Comparison with Ti-hcp and TiAl-L10 systems

Connétable

2019

International Journal of Hydrogen Energy

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“…Two antagonistic effects can be highlighted: the solubility is lower in TiAl than in Ti 3 Al or Ti, but diffusion is much faster. In the Ti 3 Al system, the stable configuration-oxygen surrounded by Ti atoms only [25]-is much more stable than the other sites that are composed of Al atoms. However, to diffuse, the O atom must necessarily pass through less stable sites, surrounded by Al atoms, so it diffuses slowly.…”

Section: Oxygen Diffusivitymentioning

confidence: 97%

Theoretical study of oxygen insertion and diffusivity in theg-TiAlL1₀system

Connétable¹,

Prillieux²,

Thenot³

et al. 2020

J. Phys.: Condens. Matter

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This work is a first-principles study of the insertion and diffusivity of oxygen in the γ-TiAl L1 0 system. Five interstitial positions were identified as stable. One, however, the 2h site a pyramid composed of a Ti square topped by an Al atom, was found more stable than the others. The oxygen interactions with the TiAl system were thus studied and analyzed in detail using vibrational, elastic and electronic properties. The results show that the O atom prefers to be surrounded by Ti atoms and tries to minimize the number of bonds with aluminum. The diffusion mechanism is subsequently studied at the atomic scale, by analyzing displacements between stable interstitial sites. The oxygen diffusivity is found to be anisotropic and the components in the x and z direction, D x and D z , are then calculated and compared with those of O diffusion into other Ti-Al alloys. The analysis of results shows two effects. First, the stability of sites is related to the number of O-Al bonds, the fewer there are, the more stable the site is, and second, the diffusion is faster when the content of interstitial sites composed of many Ti atoms is low.

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“…The α phase dominating in the TA29 alloy has the close-packed hexagonal structure (hcp, A3), where oxygen atoms tend to occupy the two Ti 6 octahedral interstitial sites [33,34], as shown in Figure 5a. The α 2 phase dominating in the Ti-24Al-15Nb-1.5Mo alloy has the ordered close-packed hexagonal structure (DO 19 ), where oxygen atoms prefer to occupy the Ti 6 octahedral interstitial site instead of the Al 2 Ti 4 site [35,36], as shown in Figure 5b. Though the number of the Ti 6 interstitial site in the lattice of the α 2 phase is lower than that in the lattice of the α phase, which leads to the lower oxygen solubility in the α 2 phase than in the α phase, the covalence of Ti-Al bond in the lattice of the α 2 phase makes electrons aggregate between Ti and Al atoms, resulting in the weaker Ti-O bond strength in the lattice of the α 2 phase compared with that in the lattice of the α phase [32].…”

Section: Resultsmentioning

confidence: 99%

Non-Isothermal Oxidation Behaviors and Mechanisms of Ti-Al Intermetallic Compounds

Ouyang

et al. 2019

Materials

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Non-isothermal oxidation is one of the important issues for the safe application of Ti-Al alloys, so this study aimed to illustrate the non-isothermal oxidation behaviors and the corresponding mechanisms of a TiAl-based alloy in comparison with a Ti3Al-based alloy. The non-isothermal oxidation behaviors of Ti-46Al-2Cr-5Nb and Ti-24Al-15Nb-1.5Mo alloys in pure oxygen were comparatively investigated with a thermogravimetry-differential scanning calorimetry (TGA/DSC) simultaneous thermal analyzer heating from room temperature to 1450 °C with a heating rate of 40 °C/min. When the temperature rose above 1280 °C, the oxidation rate of the Ti-46Al-2Cr-5Nb alloy sharply increased and exceeded that of the Ti-24Al-15Nb-1.5Mo alloy owing to the occurrence of internal oxidation. When the temperature was higher than 1350 °C, the oxidation rate of the Ti-46Al-2Cr-5Nb alloy decreased obviously due to the generation of an oxygen-barrier β-Al2TiO5-rich layer by a chemical reaction between Al2O3 and TiO2 in the oxide scale. Based on Wagner’s theory of internal oxidation, the reason for the occurrence of internal oxidation in the Ti-46Al-2Cr-5Nb alloy is the formation of the α phase in the subsurface, while no internal oxidation occurred in the Ti-24Al-15Nb-1.5Mo alloy due to the existence of the β phase in the subsurface with the enrichment of Nb and Mo.

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Absorption and diffusion of oxygen in the Ti3Al alloy

Cited by 24 publications

References 50 publications

Theoretical study of the insertion and diffusivity of hydrogen in the Ti3Al-D019 system: Comparison with Ti-hcp and TiAl-L10 systems

Theoretical study of the insertion and diffusivity of hydrogen in the Ti3Al-D019 system: Comparison with Ti-hcp and TiAl-L10 systems

Theoretical study of oxygen insertion and diffusivity in theg-TiAlL1₀system

Non-Isothermal Oxidation Behaviors and Mechanisms of Ti-Al Intermetallic Compounds

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Absorption and diffusion of oxygen in the Ti3Al alloy

Cited by 24 publications

References 50 publications

Theoretical study of the insertion and diffusivity of hydrogen in the Ti3Al-D019 system: Comparison with Ti-hcp and TiAl-L10 systems

Theoretical study of the insertion and diffusivity of hydrogen in the Ti3Al-D019 system: Comparison with Ti-hcp and TiAl-L10 systems

Theoretical study of oxygen insertion and diffusivity in theg-TiAlL10system

Non-Isothermal Oxidation Behaviors and Mechanisms of Ti-Al Intermetallic Compounds

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Theoretical study of oxygen insertion and diffusivity in theg-TiAlL1₀system