Observation using synchrotron X-ray diffraction of the crystallographic evolution of α-titanium after oxygen diffusion

Baillieux, Jean; Poquillon, Dominique; Malard, B.

doi:10.1080/09500839.2015.1014876

Cited by 16 publications

(8 citation statements)

References 19 publications

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“…When the as-cast Ti-1100-xNb alloys are oxidized at 650 • C for 100 h, both the lattice parameters 'a' and 'c' increase due to the small size interstitial oxygen dissolving into the lattice. And the lattice expansion in the c-axis direction is more severe (Figure 6c), which is consistent with the findings of Baillieux et al [23]. Jostsons et al showed that the solution of O atoms in α-Ti lattice can reach 34 at.% [24].…”

Section: Analysis Of Oxidation Kineticssupporting

confidence: 90%

Effect of Nb Content on Cyclic Oxidation Behavior of As-Cast Ti-1100 Alloys

Song

Dong

et al. 2020

Materials

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The cyclic oxidation behaviors of the as-cast Ti-1100-xNb (x = 0.5, 1.0, 1.5, 2.0) alloys exposed at 650 • C for up to 100 h were systematically investigated. The aim of this work is to explore the in-depth oxidation mechanism by using the oxidation kinetics and the structure of the oxide products. The oxidation kinetics were determined by thermogravimetrically, and the microstructure and composition of the oxidation scale were studied by using XRD and SEM. The results demonstrate that Nb can significantly improve the oxidation resistance. However, the average weight gains of the alloys decrease firstly and then increase with the increase of Nb content. The oxidation kinetics obeys a parabolic model. The Ti-1100-1.0Nb alloy has the lowest k p value, which is 5.7 × 10 −13 g 2 cm −4 s −1 . The surface oxidation products are mainly composed of massive or acicular rutile-TiO 2 , Ti x O (x = 3, 6), NbO 2 and Al 2 O 3 . Besides, Al 2 (MoO 4 ) 3 oxide is also presented on the oxidation surface of the Ti-1100-1.5Nb alloys. Ti-1100-1.0Nb alloy shows the best oxidation resistance property revealed by combining weight gains and EDS-SEM element content profiles analysis. The interaction of Nb, O, Ti, and other elements retarded the diffusion of O atoms into the alloys, which improves the oxidation resistance. surface increases, even the TiO 2 particles dissolve [10]. Researches showed that the addition of 5-10 at.% Nb could improve the oxidation resistance of Ti-Al alloys [11,12]. The effects of Nb atoms on oxidation behavior could be summarized as [13][14][15][16]: (1) Nb replaced the Ti 4+ in TiO 2 , leading to a reduce of O 2− vacancy, which hampered the diffusion of O ion. (2) Nb could improve the activity of Al and promote the formation of the density Al 2 O 3 oxide film in TiO 2 oxide-layer, which can reduce the solubility of O atoms in oxide-layer. (3) Nb could reduce the solubility of O in α-Ti phase lattice. However, the solid solubility of Nb in titanium alloys is limited, and the interaction of Nb with Al, Sn, Zr, Mo, and Si in the Ti-1100 alloy can form the secondary phase and change the surface oxide structure [7]. With increasing Nb element, excessive Nb segregates in the grain boundary, which may result in the oxide scales cracking and high temperature oxidation resistance depreciation [8,17]. The content of Nb in the near α titanium alloy is usually between 0.7-1.0 wt.% [18], and the excess Nb content can be selected as 1.5 and 2.0 wt.%.Thus, the effect of Nb content (0.5, 1.0, 1.5, 2.0 wt.%) on cyclic oxidation behavior of as-cast Ti-1100 alloys was systematically investigated in this present work. The aim of this study is to explore the in-depth oxidation mechanism from the oxidation kinetics, surface oxidation products, and the cross-section oxidation layer elements distribution.

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Section: Analysis Of Oxidation Kineticssupporting

confidence: 90%

Effect of Nb Content on Cyclic Oxidation Behavior of As-Cast Ti-1100 Alloys

Song

Dong

et al. 2020

Materials

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“…1. Similar set-up and experiments have already been used to study the phase ratio and stress gradient in ferritic thin films with a 150 nm depth resolution [21], or to measure the lattice parameter evolution in α-titanium alloy after oxidation (beam dimensions of 300 μm length and 7 μm height) [22]. The samples were illuminated at 65 keV with a beam of 5 μm height in the y direction and 100 to 800 μm length in the x direction.…”

Section: Introductionmentioning

confidence: 99%

Carburization of austenitic and ferritic stainless steels in liquid sodium: Comparison between experimental observations and simulations

et al. 2019

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Three steels were exposed in carburizing sodium at 600 and 650°C. The kinetics and extent of carburization were characterized. Numerical simulations using the coupled thermodynamic-kinetic modeling software DICTRA were performed. It was proposed that the observed carbon diffusion profiles were induced by the combined diffusion of carbon in the grains and at grain boundaries coupled with the slow formation of carbides. The blocking effect of carbides on the carbon diffusion was observed to evolve as a function of time and microstructure. Acceptable agreement between experimental and simulated intragranular carbon profiles was achieved by optimizing the labyrinth factor and phases.

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“…This can be interpreted as the following: Firstly, oxygen atoms diffuse into the metal that can occupy interstitial sites. However, the dissolved oxygen may distort the lattice by increasing the c/a ratio so that the mobility of dislocations is inhibited [28]. The dissolved oxygen atoms can find more stable places around dislocations than in the rest of the lattice.…”

Section: Influence Of Oxygen On the Hardnessmentioning

confidence: 99%

Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

Wang

Liang

Sun

et al. 2021

Metals

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The main objective of the present study was to understand the oxygen ingress in titanium alloys at high temperatures. Investigations reveal that the oxygen diffusion layer (ODL) caused by oxygen ingress significantly affects the mechanical properties of titanium alloys. In the present study, the high-temperature oxygen ingress behavior of TC21 alloy with a lamellar microstructure was investigated. Microstructural characterizations were analyzed through optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Obtained results demonstrate that oxygen-induced phase transformation not only enhances the precipitation of secondary α-phase (αs) and forms more primary α phase (αp), but also promotes the recrystallization of the ODL. It was found that as the temperature of oxygen uptake increases, the thickness of the ODL initially increases and then decreases. The maximum depth of the ODL was obtained for the oxygen uptake temperature of 960 °C. In addition, a gradient microstructure (αp + β + βtrans)/(αp + βtrans)/(αp + β) was observed in the experiment. Meanwhile, it was also found that the hardness and dislocation density in the ODL is higher than that that of the matrix.

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Observation using synchrotron X-ray diffraction of the crystallographic evolution of α-titanium after oxygen diffusion

Cited by 16 publications

References 19 publications

Effect of Nb Content on Cyclic Oxidation Behavior of As-Cast Ti-1100 Alloys

Effect of Nb Content on Cyclic Oxidation Behavior of As-Cast Ti-1100 Alloys

Carburization of austenitic and ferritic stainless steels in liquid sodium: Comparison between experimental observations and simulations

Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

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