The H−Ti (Hydrogen-Titanium) system

San-Martin, A.; Manchester, F. D.

doi:10.1007/bf02868888

Cited by 267 publications

(129 citation statements)

References 45 publications

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“…The slight shift between the peak positions of DTG and MS is possibly caused by the time delay caused by the necessary transport of the released H 2 from the furnace to the ionisation chamber of the quadrupole mass spectrometer. Obviously DSC is the most sensitive method since the onset of hydrogen release is observed at slightly lower temperatures as compared to TG and MS. Untreated TiH 2 was found to have a fcc-based CaF 2 -structure which corresponds to the δ-phase of the Ti-H system [21]. The tetragonal ǫ-phase reported for temperatures below ≈25 • C [22] is not observed, most likely because our laboratory temperature exceeded this value.…”

Section: Discussionmentioning

confidence: 69%

Modification of titanium hydride for improved aluminium foam manufacture

Matijasevic-Lux

Banhart

Fiechter³

et al. 2006

Acta Materialia

198

100

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Titanium hydride was used for foaming the aluminium casting alloy AlSi6Cu4. In order to improve foaming characteristics the TiH 2 powder was subjected to various heat treatments prior to processing to shift hydrogen release up into the melting range of the alloy. Untreated and pre-treated powders were characterised by oxygen analysis, thermal analysis in connection with mass spectrometry applying various temperature profiles, X-ray diffraction and transmission electron microscopy. In addition, foaming trials were carried out based on various TiH 2 powders. It was found that oxidation of TiH 2 particles is responsible for the observed shift in decomposition temperature since heating under argon did not produce this effect. The shift can be tailored by choosing suitable pre-treatment parameters. For an appropriate choice a beneficial effect on foam morphology was found.

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Section: Discussionmentioning

confidence: 69%

Modification of titanium hydride for improved aluminium foam manufacture

Matijasevic-Lux

Banhart

Fiechter³

et al. 2006

Acta Materialia

198

100

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“…The hydrogenation process and the equilibrium hydrogen content are a function of both the temperature and pressure of hydrogen. Figure 11 shows the equilibrium pressure of hydrogen as a function of molar content of hydrogen at different temperatures [95]. Because the equilibrium pressure of the Ti-H system increases as temperature increases, the driving force for forming hydride increases as temperature decreases, assuming the hydrogen pressure is held constant.…”

Section: Hydride-dehydridementioning

confidence: 99%

“…The yield of powder under −325 mesh (44 µm) is usually low depending on the Figure 11. The pressure-composition-temperature curves of the Ti-H system [95].…”

Section: Atomisationmentioning

confidence: 99%

Powder metallurgy of titanium – past, present, and future

Fang

Paramore

Sun

et al. 2017

International Materials Reviews

385

158

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Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium. This article examines both traditional and emerging technologies, including the production of powder, and the sintering, microstructure, and mechanical properties of PM Ti. The production methods of powder are classified into two categories: (1) powder that is produced as the product of extractive metallurgy processes, and (2) powder that is made from Ti sponge, ingot, mill products, or scrap. A new hydrogen-assisted magnesium reduction (HAMR) process is also discussed. The mechanical properties of Ti-6Al-4V produced using various PM processes are analyzed based on their dependence on unique microstructural features, oxygen content, porosity, and grain size. In particular, the fatigue properties of PM Ti-6Al-4V are examined as functions of microstructure. A hydrogen-enabled approach for microstructural engineering that can be used to produce PM Ti with wroughtlike microstructure and properties is also presented.

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“…The dehydrogenation of TiH 2 involves a number of phase transformations according to the reassessed phase diagram of Ti-H. [14] A shell of a phase was found to envelop each remaining core of titanium hydride particle. [1] This envelope of a phase not only controls the kinetics of dehydrogenation but is also expected to affect the alloying process of b-stabilizers.…”

mentioning

confidence: 99%

“…[14] Since the diffusivity of many alloying elements including V, Al, and Fe in the b phase region is known to be generally an order of (2 to 3) faster than that in the a phase region, [27] this in turn suggests that heating a TiH 2 -based powder mixture at a higher rate may enable faster densification as well as the formation of non-equilibrium phases.…”

mentioning

confidence: 99%

In Situ Synchrotron Radiation Study of TiH2-6Al-4V and Ti-6Al-4V: Accelerated Alloying and Phase Transformation, and Formation of an Oxygen-Enriched Ti4Fe2O Phase in TiH2-6Al-4V

Yan

Dargusch

Kong

et al. 2014

Metall Mater Trans A

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In situ heating, synchrotron radiation X-ray diffraction has been used to study the alloying and phase transformation behavior of TiH 2 -6Al-4V and Ti-6Al-4V alloys. Accelerated alloying and phase transformation were observed in the powder compact of the TiH 2 -6Al-4V alloy subjected to a high heating rate. In addition, an oxygen-stabilized Ti 4 Fe 2 O phase, which is present as sub-micron or nanoscaled particles, has been identified in the TiH 2 -6Al-4V alloy. The implications of these experimental findings have been discussed in terms of alloying, improved densification and oxygen scavenging in titanium and titanium alloys. Titanium hydride, normally referred to as the d-TiH 2 phase [face-centred cubic (fcc) with a = 4.36 Å ], is a compound stable at room temperature (RT) but will decompose at elevated temperatures. Its transformation is dependent on atmosphere, heating rate, and powder size (if TiH 2 in present as powder), as well as temperature. [1][2][3] TiH 2 has attracted extensive research interest for applications in hydrogen storage, [4] metal foaming, [5] and hydroprocessing. [6] In the context of powder metallurgy (PM), research on TiH 2 was initiated in the 1960s [7] but recent years have seen a significant renewed interest in PM TiH 2 for a few good reasons, including [8][9][10][11][12][13] : (a) the use of TiH 2 powder can result in higher sintered densities and often better mechanical properties; (b) TiH 2 powder can be more affordable than the hydride-dehydride (HDH) Ti powder; and (c) the use of TiH 2 powder can lead to lower oxygen content in as-sintered Ti materials. This is due to the release of atomic hydrogen after heating of TiH 2 , which can reduce the surface oxide film on the TiH 2 powder particles. As a result of these benefits, PM TiH 2 shows promise as means to develop more affordable, high-performance PM titanium alloys.The dehydrogenation of TiH 2 involves a number of phase transformations according to the reassessed phase diagram of Ti-H.[14] A shell of a phase was found to envelop each remaining core of titanium hydride particle.[1] This envelope of a phase not only controls the kinetics of dehydrogenation but is also expected to affect the alloying process of b-stabilizers.[1] Ivasishin and Savvakin [15] first proposed that the use of a fast heating rate could avoid the formation of this a shell during the decomposition of TiH 2 ; doing so is expected to favor the alloying process with b-stabilizers as the a shell acts as a barrier to the diffusion of b-stabilizers. This represents another potential unique feature of the PM TiH 2 but no direct evidence has been reported yet. One reason is that most relevant studies including the sintering of titanium alloys using TiH 2 powder were carried out at heating rates of less than 30°C/min, [3,8,[10][11][12][13] which has been shown to be inadequate to avoid the formation of the a phase. [3] The other reason is that it requires the use of in situ, instantaneous and high-temperature phase identification to monitor phase transformation du...

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The H−Ti (Hydrogen-Titanium) system

Cited by 267 publications

References 45 publications

Modification of titanium hydride for improved aluminium foam manufacture

Modification of titanium hydride for improved aluminium foam manufacture

Powder metallurgy of titanium – past, present, and future

In Situ Synchrotron Radiation Study of TiH2-6Al-4V and Ti-6Al-4V: Accelerated Alloying and Phase Transformation, and Formation of an Oxygen-Enriched Ti4Fe2O Phase in TiH2-6Al-4V

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