Diffusion of Titanium and Nickel in B2 NiTi

Divinski, Sergiy V.; Stloukal, Ivo; Král, Lubomír; Herzig, Christian

doi:10.4028/www.scientific.net/ddf.289-292.377

Cited by 36 publications

(16 citation statements)

References 12 publications

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“…If the diffusion mechanism could be considered as vacancy mediated, then we have: E D =E v + E m = 0.78eV+0.7eV=1.48 eV, which is practically coincides with E D determined by radio-tracer method [1,2,31]. According to diffusion data the most probable atom jump is the next-nearest-neighbour jump [32]. Experiments in quasielastic neutron scattering [33] showed that elementary diffusion in B2 compounds occurs via nearest neighbour jumps of atoms.…”

mentioning

confidence: 72%

“…This method showed that Ti atoms diffused to one-two order slower than Ni atoms. It was proposed [2] that as Ni atoms are smaller than Ti atoms they could diffuse by interstitial diffusion mechanism, however, this is impossible [32]. Another assumption also [2,31] has been excluded, i.e.…”

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confidence: 99%

“…Different diffusion mechanisms are proposed following which diffusion in B2 structure is possible (6-jump cycle, triple defect mechanism and others) [30]. The diffusion mechanism in TiNi has been investigated by the radio-tracer method [2,31,32]. This method showed that Ti atoms diffused to one-two order slower than Ni atoms.…”

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confidence: 99%

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Formation of vacancy-type defects in titanium nickelide

Батурин

Лотков

Гришков

et al. 2015

MATEC Web of Conferences

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Abstract. In this report we briefly review the current state-of-the-art and challenges in determining point defect properties from first-principles calculations as well as from experimental measurements in titanium nickelid. Based on the vacancy formation energy and the activation energy for vacancy migration in TiNi, vacancy mediated diffusion mechanism was examined. The influence of vacancies and antisite defects on the TiNi structural phase transition has been described. IntroducingInvestigating diffusion processes in titanium nickelid alloys sharpened several issues on types and characteristic features of point defects. In the publication of Bastin and Riek [1] it was established that the chemical diffusion coefficient in TiNi is determined by Ni diffusion, and the activation energy for diffusion is too small (~1.4 eV) compared to other B2 intermetallic compounds. Investigating Ni diffusion in relation to pressure [2] showed that activation volume of diffusion Ni in TiNi within experimental error is equals zero. This could imply that diffusion mechanism is interstitial mediated or that there are structural vacancies in the intermetallic compound. Diffusion mechanism in TiNi is a particular case to explain the common diffusion mechanism in B2 intermetallic compounds. As discussion of the diffusion mechanism in B2 intermetallic, causes disputes [3][4][5], research of point defects in TiNi is relevant. Besides, some authors [6][7][8][9] state that point defects configuration of a B2 phase can play an important role in nucleation and growth processes of martensitic phase. Vacancy formation energy in titanium nickelidIn AB compounds with B2 structure interatomic potentials of identical atoms AA and BB have distinct dependency on the distance between identical atoms in given coordination sphere; further, interatomic potentials of these identical atoms also have a different potential well [9]. This results in the fact that the vacancy formation energy (E v ) on the different atomic sublattices is non-identical, which, in its turn, could be revealed in some B2 compounds by the positron annihilation spectroscopy (PAS) method [10].Presently, investigations in measurement the vacancy formation energy in a series of intermetallic compounds In the reference well-annealed state average positron lifetime corresponds to a delocalized positron state, i.e. the vacancy concentration in a sample lower than the PAS method threshold limit. Further, when heating the a Corresponding author: abat@ispms.tsc.ru

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confidence: 72%

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confidence: 99%

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Formation of vacancy-type defects in titanium nickelide

Батурин

Лотков

Гришков

et al. 2015

MATEC Web of Conferences

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“…This was governed by the higher rate of self-diffusion on the Ti substrate compared to the rate of primary deposition on the nickel substrate, attributed to the higher self-diffusion coefficient of Ti 33 compared to the diffusion coefficient of Ti or Ni in the Ni−Ti alloy. 34 With deposit growth, the local potential gradient gradually reduced. The cathodic process and Ti deposition indicated that Ti electrorefining from the CuTi alloy is highly feasible; however, its anodic processes require investigation.…”

Section: Acs Sustainablementioning

confidence: 99%

Carbon-Free Recovery Route for Pure Ti: CuTi-Alloy Electrorefining in a K-Free Molten Salt

Yoo

Nersisyan

et al. 2023

ACS Sustainable Chem. Eng.

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Metallic titanium is commonly produced by the carbon-dioxide-emitting Kroll process. The modern shift to sustainable technology has generated global interest in green processes. A carbon-free route for Ti manufacturing via the fabrication of a copper–titanium alloy and its electrorefining has been previously reported. This study focuses on the sustainability of the Ti-production electrorefining process (using a CuTi-alloy anode in LiF–NaF molten salt, with BaTiF6 addition, at 750 °C). BaTiF6, produced by a chemical reaction, was used as a K-free alternative to K2TiF6. The Ti-reduction mechanism and the anodic dissolution of Ti, CuTi, and Cu were investigated by potential sweep methods. Selective anodic dissolution of Ti, without Cu codissolution, occurred in a wide anodic potential range (−0.6 to 0.9 V vs W). Moreover, the Cu matrix remained on the anode, without sludge formation in the electrolyte, eliminating Ti-deposit recontamination by the anode material. Energy consumption and CO2 emissions were 1.66 times less than those of the Kroll process. The Ti-deposit morphology (with temperature, current density, and electrolysis-duration variation) was analyzed by scanning electron microscopy (SEM). Additional experimentation indicated that Ti can be electrochemically separated from Fe, confirming that low-grade TiO2 raw materials and off-grade Ti sponge could be used for the fabrication and processing of CuTi anodes.

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“…In plasma sintering diffusion is favored, besides the temperature, by the pulsating current by increasing the density of point defects, by lowering the activation energies needed to displace these defects, as well as by electromigration [17]. Thus, taking into account the higher Ni diffusion coefficient than that of Ti in NiTi [18], as well as the reinforcement particulates high Ni content, it is possible to obtain a Ni -rich NiTi phase.…”

Section: Magnesium Composites Reinforced With Mechanical Alloyed Nickmentioning

confidence: 99%

Microstructural Aspects of Some Magnesium Matrix Composites Reinforced with Amorphous/Nanocrystalline Ni-Ti Particulates

Dumitrescu¹,

Gherghescu²,

Ciucă³

et al. 2019

Rev. Chim.

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Two magnesium matrix composites reinforced with 3 and 10% Ni-Ti particulates, respectively, were obtained by plasma sintering. The reinforcement material was obtained by grinding a mixture of powders of 68% Ni and 32% Ti atomic percent in a high energy mill for 40 hours. Particulates resulting from mechanical alloying have a partially amorphous and partially nanocrystalline structure, consisting of the following phases: Ni solid solution, Ti2Ni and NiTi (B2) phase. After sintering, both the matrix and the reinforcement material are nanocrystalline and the particulates have a polyphase structure, consisting of Ni(Ti), NiTi (R phase) and Ni4Ti3. The hardness of these composites is superior to the hardness of magnesium matrix composites reinforced with Ni-Ti particulates having 50% Ni / 50% Ti and 32% Ni / 68% Ti chemical compositions obtained under the same conditions and corresponding proportions of reinforcement material.

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Diffusion of Titanium and Nickel in B2 NiTi

Cited by 36 publications

References 12 publications

Formation of vacancy-type defects in titanium nickelide

Formation of vacancy-type defects in titanium nickelide

Carbon-Free Recovery Route for Pure Ti: CuTi-Alloy Electrorefining in a K-Free Molten Salt

Microstructural Aspects of Some Magnesium Matrix Composites Reinforced with Amorphous/Nanocrystalline Ni-Ti Particulates

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