High-temperature oxidation of titanium-hydride powders

Lavrenko, V. A.; Shemet, V.; Petrov, L. A.; Teplov, O. A.; Dolukhanyan, S. K.

doi:10.1007/bf00665675

Cited by 22 publications

(8 citation statements)

References 1 publication

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“…The only easily visible change is the colour of the powder. As thin films build up the optical properties change and the powder goes through a series of colours [16,24]. TEM observation clearly reveals these oxide films (Fig.…”

Section: Discussionmentioning

confidence: 99%

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: 99%

Modification of titanium hydride for improved aluminium foam manufacture

Matijasevic-Lux

Banhart

Fiechter³

et al. 2006

Acta Materialia

198

100

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“…In the literatures, 1,2,[13][14][15] there are different explanations of the phenomenon. Trefilow et al 14) indicates that hydrogen atom placed into different places in the TiH 2 lattice, namely octahedral and tetrahedral holes in -TiH 2 .…”

Section: Resultsmentioning

confidence: 99%

“…13,14) The hydrogen atoms in octahedral holes can easily migrate because the bonding in octahedral sites is weaker than that in tetrahedral ones. 15) Therefore, during heating the hydrogen atoms from the octahedral positions would be released first and the hydrogen from the tetrahedral ones should leave later. On the other hand, Kennedy claims that first the reduction in the stoichiometry of the hydride to -TiH 1:5 hydride occurs, and second the heating leads to both hydride decomposition and the formation of -and -Ti phases.…”

Section: Resultsmentioning

confidence: 99%

Heat Treatment of TiH<SUB>2</SUB> Powder to Control Decomposition Phenomenon for Aluminum Foam Fabrication by Melt Route

2009

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TiH 2 powder has been used to fabricate aluminum foams as a blowing agent for more than two decades. The aim of this paper is to understand the detailed decomposition behavior of TiH 2 powder and to control the phenomenon by a heat treatment for the fabrication of fine aluminum foams by the melt route. TiH 2 powders whose qualities were different, were characterized using TG-DTA and XRD. As heat treatment factors, temperature and time were applied. We have found differences in the decomposition behavior between the as-received TiH 2 powders. Regardless of quality of TiH 2 powder, increasing temperature and time of the heat treatment in air elevates the decomposition temperature and decreases the amount of released hydrogen during reheating due to the oxide barrier layer formed on the powder surface. The influence of the heat treatment temperature on the decomposition modification is more significant than that of the time. To control the decomposition phenomenon of TiH 2 powder, the heat treatment condition has to be optimized taking into account the quality and the purity of the powder.

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“…a-ZrO 2 (badellyite) was found in the Zr and in the ZrD 2 powder, in which we estimated Zr:O:D::1:0.1:1.9 from the phase assemblage. No free oxide was found on the Ti, but there is a high degree of solubility of O in the octahedral interstices of the a-andb-phases of these metals and even the (oxy)hydrides [10][11][12]. As H typically is found in the tetrahedral interstices of metals, there is usually not direct competition for sites with O.…”

Section: Precursor Materialsmentioning

confidence: 99%

Omega-phase in Ti-Hf-Zr alloys produced by the hydride-cycle methodSpecial issue on Neutron Scattering in Canada.

et al. 2010

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Abstract:We report the presence of large proportions of u-phase in Ti-Hf-Zr alloys, prepared using the hydride cycle technique. We show that the u-phase extends across the concentration triangle of Ti-Zr-Hf and report the partitioning of the three metals across the two sites in this structure from neutron and X-ray data. We examine the symmetry of the order parameter governing the b-u phase transition and show that a two-step model for the phase transition involving site ordering followed by displacement is not likely to be correct. We suggest that an interstitial solid solution of oxygen and octahedral vacancies exists, and that the observation of any u-phase diffraction pattern of alloys of these metals at ambient temperature and pressure should be viewed as a potential sign of the presence of oxygen in the octahedral interstitial sites. Résumé : Dans cet article, nous rapportons la présence d'une importante proportion de la phase dite u dans les alliages Ti-Hf-Zr, préparés par une technique de cyclage sous hydrogène (hydride cycle). Nous montrons également que la phase u s'étend à travers le diagramme de concentration triangulaire de Ti-Hf-Zr. De plus, à partir de données de diffractions des neutrons, nous trouvons que les trois métaux se répartissent sur les deux sites distincts dans la structure. Nous examinons la symetrie du paramètre d'ordre qui gouverne la transition de phase b-u et nous montrons qu'un modèle à deux étages pour la transition de phase est improbable. Nous suggérons plutôt la présence d'une solution solide interstitielle d'oxygène et de lacunes octaédriques. De plus, si la phase u est observée dans le diagramme de diffraction d'alliages de ces métaux à température et pression ambiente, on doit la considérer comme un signe possible de la présence d'oxygène sur les sites interstitiels octaédriques.

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High-temperature oxidation of titanium-hydride powders

Cited by 22 publications

References 1 publication

Modification of titanium hydride for improved aluminium foam manufacture

Modification of titanium hydride for improved aluminium foam manufacture

Heat Treatment of TiH<SUB>2</SUB> Powder to Control Decomposition Phenomenon for Aluminum Foam Fabrication by Melt Route

Omega-phase in Ti-Hf-Zr alloys produced by the hydride-cycle methodSpecial issue on Neutron Scattering in Canada.

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