Phase transformations in equiatomic alloy TiZr at pressure up to 70 kbar

Bashkin, I. O.; Pagnuev, A. Yu.; Gurov, A. F.; Федотов, В. К.; Abrosimova, G. E.; Ponyatovskiĭ, E. G.

doi:10.1134/1.1131187

Cited by 12 publications

(42 citation statements)

References 5 publications

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“…The ω-phase recovered from the high-pressure experiments at room and moderate temperatures has also been reported to form continuous solid solutions [2,6]. The ω-phase solid solutions showed the concentration dependence of the specific volume close to the Vegard's law, and the reported values of the specific volumes were by less than 1 % above the straight line drawn between the volumes of pure elements.Earlier, the pressure effect on the phase diagram has been studied by means of the differential thermal analysis (DTA) carried out on the equiatomic TiZr alloy up to 7 GPa [2]. There were plotted the lines of the isoconcentrational α↔β and β↔ω transformations.…”

mentioning

confidence: 92%

“…Both phases of the Ti−Zr system form continuous solid solutions, and characteristic of the T−C phase diagram is the monotectic point located at 52 at.% Zr [1] and 852 K [2]. Applied pressure induces a transition of the α-phase to the hexagonal ω-phase both in elemental Ti and Zr [3][4][5] and in the binary Ti−Zr alloys [2,6].…”

Section: Introductionmentioning

confidence: 99%

“…Applied pressure induces a transition of the α-phase to the hexagonal ω-phase both in elemental Ti and Zr [3][4][5] and in the binary Ti−Zr alloys [2,6]. The ω-phase recovered from the high-pressure experiments at room and moderate temperatures has also been reported to form continuous solid solutions [2,6]. The ω-phase solid solutions showed the concentration dependence of the specific volume close to the Vegard's law, and the reported values of the specific volumes were by less than 1 % above the straight line drawn between the volumes of pure elements.…”

Section: Introductionmentioning

confidence: 99%

“…Earlier, the pressure effect on the phase diagram has been studied by means of the differential thermal analysis (DTA) carried out on the equiatomic TiZr alloy up to 7 GPa [2]. There were plotted the lines of the isoconcentrational α↔β and β↔ω transformations.…”

Section: Introductionmentioning

confidence: 99%

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Decomposition of the ω-phase in the equiatomic TiZr alloy under high pressure

Bashkin

Shestakov

Sakharov

et al. 2008

J. Phys.: Conf. Ser.

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Abstract. The phase decomposition phenomenon is found in the hexagonal ω-phase of the Ti−Zr system under high pressure. The ω → ω 1 + ω 2 decomposition of the equiatomic TiZr alloy occurred due to long thermobaric treatment at P = 5.5±0.6 GPa and T = 710±30 K. The chemical compositions of the ω 1 -and ω 2 -phases recovered to ambient conditions were estimated from the Xray data to be around Ti 20 Zr 80 and Ti 83 Zr 17 . The experimental data were used to calculate the mixing energy and the top of the decomposition curve in the isobaric T−C diagram of this system. We find that the equilibrium T−C phase diagram of the Ti−Zr system at pressures above ~8 GPa is of the eutectoid type with the high-temperature β-phase and the low-temperature ω 1 -and ω 2 -phases. IntroductionTwo modifications are known for titanium and zirconium at atmospheric pressure, the low-temperature hexagonal close-packed (hcp) α-phase and the high-temperature body-centered cubic (bcc) β-phase. Both phases of the Ti−Zr system form continuous solid solutions, and characteristic of the T−C phase diagram is the monotectic point located at 52 at.% Zr [1] and 852 K [2]. Applied pressure induces a transition of the α-phase to the hexagonal ω-phase both in elemental Ti and Zr [3][4][5] and in the binary Ti−Zr alloys [2,6]. The ω-phase recovered from the high-pressure experiments at room and moderate temperatures has also been reported to form continuous solid solutions [2,6]. The ω-phase solid solutions showed the concentration dependence of the specific volume close to the Vegard's law, and the reported values of the specific volumes were by less than 1 % above the straight line drawn between the volumes of pure elements.Earlier, the pressure effect on the phase diagram has been studied by means of the differential thermal analysis (DTA) carried out on the equiatomic TiZr alloy up to 7 GPa [2]. There were plotted the lines of the isoconcentrational α↔β and β↔ω transformations. The α−β transformation had a hysteresis of 70 K whereas the hysteresis of the β−ω transformation was close to zero, and the parameters of the α−β−ω triple point determined by DTA were as low as P = 4.9 GPa and T = 733 K. In contrast, the hysteresis of the

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mentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Decomposition of the ω-phase in the equiatomic TiZr alloy under high pressure

Bashkin

Shestakov

Sakharov

et al. 2008

J. Phys.: Conf. Ser.

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“…In high-purity Ti and Zr, the u-phase appears as the thermodynamically stable phase at P > 40-70 kbar (1 bar = 100 kPa) [15][16][17]. The relationship to the bcc b-phase of such metals is simple and can be viewed as a displacive mechanism.…”

Section: The U-phasementioning

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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