Diffusion of hydrogen in the shape memory alloy Ni47Ti40Hf10Cu3

Biscarini, A.; Coluzzi, B.; Mazzolai, Giovanni; Mazzolai, F.M.

doi:10.1016/j.jallcom.2004.12.159

Cited by 12 publications

(17 citation statements)

References 20 publications

(27 reference statements)

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“…figure 14 taken from ref. 43. Two thermally activated peaks are introduced by H at around 240 and 40 K. The activation energy of the higher-temperature peak was found to be 0.6±0.01 eV, that of the other 0.010±0.003 eV.…”

Section: According To Ref 23 the Temperatures T G Of The E(t) Dip Dementioning

confidence: 87%

Recent progresses in the understanding of the elastic and anelastic properties of H-free, H-doped and H-contaminated NiTi based alloys

Mazzolai¹

2011

AIP Advances

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This review is focused on the influence of interstitial hydrogen and alloy compositional changes on the internal friction (IF) spectrum and elastic Young's modulus (E) of NiTi based shape memory alloys. In the martensitically transforming binary alloys Ni50+xTi50-x (x≤1.3) vacuum annealed and furnace cooled (H-free), besides the well known IF peak associated with the martensitic transition two additional non-thermally activated peaks (P150K and P200K′) are present due to some sort of second-order phase transitions. In martensitically transforming Ni50+xTi50-x and Ti50Ni50-yCuy alloys doped with hydrogen two thermally activated peaks, PTWH and PH, appear which originate from stress-assisted motions of H-twin boundary complexes and isolated H-elastic dipoles (Snoek effect), respectively. In a H-free martensitically non-trasforming alloy (x=2), besides the non-thermally activated peak P150K, a frequency dependent dip is observed in the E(T) curves at a temperature Tg. This dip is similar to that reported in the literature for two other non-transforming alloys (x=1.5 and x=2.5), which, however, were also found to exhibit a thermally activated IF peak just below Tg. Most likely, these two alloys were contaminated with hydrogen during the preliminary solubilization in argon atmosphere and subsequent water quenching treatments given to them. The Young's modulus dip and the lower temperature IF peak have been both attributed to a novel type of phase transition reported in the literature as “strain glass transition”. The introduction of hydrogen into the non-transforming alloy with x=2 enhances the Young's modulus dip and gives rise to the H-Snoek peak PH just below Tg, which clearly appears to be the counterpart of the peak observed in the alloys (x=1.5 and x=2.5) solubilized in argon atmosphere and water quenched. The conclusion was reached in the present work that this last peak is not related to the strain glass transition but is rather an H-Snoek relaxation

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Section: According To Ref 23 the Temperatures T G Of The E(t) Dip Dementioning

confidence: 87%

Recent progresses in the understanding of the elastic and anelastic properties of H-free, H-doped and H-contaminated NiTi based alloys

Mazzolai¹

2011

AIP Advances

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“…However, there are few reports involving quantitative decomposition of IF spectra for Ti 50 Ni 27 Cu 23 SMA except the present authors' study on the dependence of transitory IF spectra on low oscillation frequency by an iterative method [3][4][5][6][7]. In this paper, the dependence of the transitory IF spectra on temperature rate for Ti 50 Ni 27 Cu 23 SMA has been studied using an iterative approach.…”

Section: Introductionmentioning

confidence: 89%

“…The high damping capacity of the thermoelastic TiNi-based shape memory alloy (SMA), an optimal candidate, is closely associated with the hysteresis movement of martensite variant interfaces or/and twin boundaries [1][2][3][4][5][6]. TiNiCu SMA is known for higher damping capacity in addition to its narrow temperature hysteresis [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Influence of temperature rate on transitory internal friction during reverse martensitic transformation for Ti50Ni27Cu23 alloy

Wang

et al. 2010

Rare Metals

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Internal friction (IF) spectra during reverse martensitic transformation from 35 to 135°C at different temperature rates of 0.5, 0.75, and 1°C/min for Ti 50 Ni 27 Cu 23 shape memory alloy (SMA) samples were measured with a dynamic mechanical analyzer, respectively. The IF spectra were characterized by IF peak increasing progressively and peak shifting toward high temperature with an increase in temperature rate. An iterative approach was used to calculate the precise intrinsic and approximate transitory IF contributions to the normal IF spectrum. The quantitatively analyzed results indicate that the transitory IF of this alloy is nonlinearly dependent on the temperature rate and obeys a power law with a power coefficient of 0.55. The predicted and experimental IF spectra at different temperature rates of 0.75 and 1°C/min agree well with each other, respectively.

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“…[16][17][18][19][20][21]. Mazzolai and co-workers investigated and reported important parameters describing solubility and diffusion of interstitial hydrogen in the bulk NiTi SMAs [17,18].…”

Section: Introductionmentioning

confidence: 99%

Ab initiostudy of point defects in NiTi-based alloys

et al. 2014

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Changes in temperature or stress state may induce reversible B2↔(R)↔ B19' martensitic transformations and associated shape memory effects in close-to-stoichiometric nickel-titanium (NiTi) alloys. Recent experimental studies confirmed a considerable impact of the hydrogen-rich aging atmosphere on the subsequent B2 austenite ↔ B19' martensite transformation path. In this paper, we employ Density Functional Theory to study properties of Ar, He, and H interstitials in B2 austenite and B19' martensite phases. We show that H interstitials exhibit negative formation energies, while Ar and He interstitials yield positive values. Our theoretical analysis of slightly Ni-rich Ni-Ti alloys with the austenite B2 structure shows that a slight over-stoichiometry towards Ni-rich compositions in a range 51-52 at.% is energetically favorable. The same conclusion holds for H-doped NiTi with the H content up to ≈ 6 at.%. In agreement with experimental data we predict H atoms to have a strong impact on the martensitic phase transformation in NiTi by altering the mutual thermodynamic stability of the high-temperature cubic B2 and the low-temperature monoclinic B19' phase of NiTi. Hydrogen atoms are predicted to form stable interstitial defects. As this is not the case for He and Ar, mixtures of hydrogen and the two inert gases can be used in annealing experiments to control H partial pressure when studying the martensitic transformations in NiTi in various atmospheres.

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Diffusion of hydrogen in the shape memory alloy Ni47Ti40Hf10Cu3

Cited by 12 publications

References 20 publications

Recent progresses in the understanding of the elastic and anelastic properties of H-free, H-doped and H-contaminated NiTi based alloys

Recent progresses in the understanding of the elastic and anelastic properties of H-free, H-doped and H-contaminated NiTi based alloys

Influence of temperature rate on transitory internal friction during reverse martensitic transformation for Ti50Ni27Cu23 alloy

Ab initiostudy of point defects in NiTi-based alloys

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