Gas-phase hydrogenation influence on defect behavior in titanium-based hydrogen-storage material

Laptev, Roman; Kudiiarov, Viktor N.; Bordulev, Yuri S.; Mikhaylov, Andrey; Лидер, А. М.

doi:10.1016/j.pnsc.2017.01.001

Cited by 26 publications

(16 citation statements)

References 24 publications

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“…The component τ A = 166 ± 2 ps is related to annihilation of positrons trapped by dislocations in titanium [21,22]. The long-lived component τ B = 276 ± 6 ps is responsible for the annihilation of positrons in complex hydrogenvacancy clusters mV-nH (where m is the number of vacancies in cluster and n is the number of hydrogen atoms associated with a cluster) [27].…”

Section: Resultsmentioning

confidence: 99%

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Positron Spectroscopy of Hydrogen-Loaded Ti-6Al-4V Alloy with Different Defect Structure

et al. 2020

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The defect structure of annealed cast, electron beam melted and ultrafine-grained titanium Ti-6Al-4V alloys before and after hydrogenation was studied. It has been established that before hydrogenation the predominant types of defects in electron beam melted and ultrafine-grained titanium alloy are dislocations and low-angle boundaries, respectively. The cast alloy after annealing is defect-free material. Hydrogenation from the gas phase to 1.00 ± 0.15 wt% leads to an increase of the concentration of the predominant type of defects. Moreover, vacancy complexes also presented in electron beam melted and ultrafine-grained Ti-6Al-4V alloys interact with hydrogen and form hydrogen-vacancy complexes.

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Section: Resultsmentioning

confidence: 99%

“…After hydrogenation, the intensity of the dislocation component increases 4.7 times, while the lifetime of the long-lived component decreases significantly (to 207 ps) with intensity growing to 14%. Thus, the concentration of dislocations increases and hydrogenvacancy complexes (V-1H) are formed upon hydrogenation of EBM Ti-6Al-4V alloy [27].…”

Section: Resultsmentioning

confidence: 99%

Positron Spectroscopy of Hydrogen-Loaded Ti-6Al-4V Alloy with Different Defect Structure

et al. 2020

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“…% of hydrogen below 300 • C would start the formation of the delta hydride phase. Based on [3,37,38], this process leads to the growth of microstresses and dislocation density inside many materials, including Ti, and explains the sharp change in the trend of the line-shape parameters of DBS spectra.…”

Section: Discussionmentioning

confidence: 98%

“…% of hydrogen below 300 °C would start the formation of the delta hydride phase. Based on [3,37,38], this process leads to the growth of microstresses and dislocation density inside many materials, including Ti, and explains the sharp change in the trend of the line-shape parameters of DBS spectra. Significant changes became noticeable when the sandwich was heated to 600 • C. We can conclude that the concentration of thermal vacancies exceeds the sensitivity threshold of this technique at 600 • C. This threshold could likely be lowered by using thinner foil (thus increasing the number of positrons annihilating in the studied sample).…”

Section: Performance Of 64 Cu At High Temperatures and In A Hydrogen Atmospherementioning

confidence: 98%

Source for In Situ Positron Annihilation Spectroscopy of Thermal—And Hydrogen-Induced Defects Based on the Cu-64 Isotope

et al. 2021

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This work aims to investigate the 64Cu isotope applicability for positron annihilation experiments in in situ mode. We determined appropriate characteristics of this isotope for defect studies and implemented them under aggressive conditions (i.e., elevated temperature, hydrogen environment) in situ to determine the sensitivity of this approach to thermal vacancies and hydrogen-induced defects investigation. Titanium samples were used as test materials. The source was obtained by the activation of copper foil in the thermal neutron flux of a research nuclear reactor. Main spectrometric characteristics (e.g., the total number of counts, fraction of good signals, peak-to-noise ratio) of this source, as well as line-shaped parameters of the Doppler broadening spectrum (DBS), were studied experimentally. These characteristics for 64Cu (in contrast to positron sources with longer half-life) were shown to vary strongly with time, owing to the rapidly changing activity. These changes are predictable and should be considered in the analysis of experimental data to reveal information about the defect structure. The investigation of samples with a controlled density of defects revealed the suitability of 64Cu positron source with an activity of 2–40 MBq for defects studies by DBS. However, greater isotope activity could also be applied. The results of testing this source at high temperatures and in hydrogen atmosphere showed its suitability to thermal vacancies and hydrogen-induced defects studies in situ. The greatest changes in the defect structure of titanium alloy during high-temperature hydrogen saturation occurred at the cooling stage, when the formation of hydrides began, and were associated with an increase in the dislocation density.

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“…Positron annihilation (PA) techniques, such as positron lifetime spectroscopy (PLS) and Doppler broadening spectroscopy (DBS), are promising nuclear-physical methods for investigating structural defects in different materials, including ultrafine-grained and nanostructured materials [ 10 , 11 , 12 , 13 ]. The efficiency of PA methods for studying carbon based materials was demonstrated in [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

et al. 2018

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The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation.

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Gas-phase hydrogenation influence on defect behavior in titanium-based hydrogen-storage material

Cited by 26 publications

References 24 publications

Positron Spectroscopy of Hydrogen-Loaded Ti-6Al-4V Alloy with Different Defect Structure

Positron Spectroscopy of Hydrogen-Loaded Ti-6Al-4V Alloy with Different Defect Structure

Source for In Situ Positron Annihilation Spectroscopy of Thermal—And Hydrogen-Induced Defects Based on the Cu-64 Isotope

Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

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