Investigation on the Effect of Ta Additions on $J_{c}$ and $n$ of $({\rm Nb},{\rm Ti})_{3}{\rm Sn}$ Bronze Processed Multifilamentary Wires at High Magnetic Fields

Abächerli, V.; Buta, F.; Uglietti, D.; Senatore, Carmine; Seeber, B.; Flükiger, R.

doi:10.1109/tasc.2007.899356

Cited by 9 publications

(11 citation statements)

References 14 publications

(14 reference statements)

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“…We have investigated three Nb 3 Sn multifilamentary wires produced by different techniques, namely powder-in-tube method [5], bronze route [6] and internal tin rod restack process [7]. Samples have been labelled as PIT#1, BR#1 and IT#1, according to the fabrication technique used.…”

Section: B Samplesmentioning

confidence: 99%

Thermal Conductivity of Industrial $\hbox{Nb}_{3} \hbox{Sn}$ Wires Fabricated by Various Techniques

Bonura

Senatore

2013

IEEE Trans. Appl. Supercond.

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Abstract-We have developed a new experimental setup specifically designed for measuring thermal conductivity on technical superconductors in the range of temperatures 3-330 K in magnetic fields up to 21 T. Three Nb 3 Sn wires, produced by the powder-in-tube technique, the bronze route and the internal tin restacked-rod process, respectively, have been investigated. We show that, due to the complexity of the architecture of these wires, direct measurement of thermal conductivity is required for a correct estimation of thermal stability in superconducting magnets.

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Section: B Samplesmentioning

confidence: 99%

Thermal Conductivity of Industrial $\hbox{Nb}_{3} \hbox{Sn}$ Wires Fabricated by Various Techniques

Bonura

Senatore

2013

IEEE Trans. Appl. Supercond.

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“…Since longer annealing times only lead to larger grains, but do not cause observable changes in the atomic compositions, the A15 phase limits in the filaments are thought to be quite close to thermal equilibrium, thus allowing the representation of the phase fields shown in figures 1 and 2. One measurement was performed on an optimized multifilamentary Nb 3 Sn wire reacted at 670 • C [5]. Since this wire had an unreacted Nb core, thus giving rise to a strong Sn gradient in the A15 layer [13], the TEM/EDX measurement was performed on the equiaxed grains close to the bronze interface [5].…”

Section: The Occupancy Of A15 Sites In Nb 3 Sn Wires By Ta and Ti Add...mentioning

confidence: 99%

“…In the second part, an answer is given to the question why a deviation from the linear Kramer relation [1] is observed in bronze route Nb 3 Sn wires [2], in contrast to internal Sn and powder-in-tube (PIT) wires. Finally, the effect of additives is analyzed for MgB 2 wires, where a new way for optimization is explored: the simultaneous addition of elements or compounds to the original powders of in situ MgB 2 wires, in view of applications at 20 K. Pseudobinary A15 phase field of the system Nb-Sn-Ta, as derived from the data of Livingston et al [9], Suenaga et al [10], Tafto et al [7] and Abächerli et al [5], in the temperature range between 700 and 750 • C. field, B c2 [3,4] and thus of J c at high magnetic fields. Recent works show a further enhancement of J c by substituting the combination of Ta + Ti [5], while an enhancement of B c2 for Ga additions was also reported on thin films [6].…”

Section: Introductionmentioning

confidence: 99%

“…Finally, the effect of additives is analyzed for MgB 2 wires, where a new way for optimization is explored: the simultaneous addition of elements or compounds to the original powders of in situ MgB 2 wires, in view of applications at 20 K. Pseudobinary A15 phase field of the system Nb-Sn-Ta, as derived from the data of Livingston et al [9], Suenaga et al [10], Tafto et al [7] and Abächerli et al [5], in the temperature range between 700 and 750 • C. field, B c2 [3,4] and thus of J c at high magnetic fields. Recent works show a further enhancement of J c by substituting the combination of Ta + Ti [5], while an enhancement of B c2 for Ga additions was also reported on thin films [6]. The question is raised whether a particular combination of additives could lead to a further enhancement of the critical current density, J c , at high magnetic fields.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of Nb₃Sn and MgB₂wires

Flükiger

Senatore

Cesaretti

et al. 2008

Supercond. Sci. Technol.

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The critical current density in industrial Nb 3 Sn and MgB 2 wires is currently optimized by introducing various kinds of additives, either Ta and/or Ti for Nb 3 Sn wires or SiC or C for MgB 2 wires. In the following, several problems linked to the presence of additives in the two classes of compounds are discussed.A reinvestigation of the site occupancy of Ta and Ti additives in Nb 3 Sn wires shows that the Ta atoms occupy the 6c chain sites, while the Ti atoms are located on the cubic 2a sites. It follows that in perfectly ordered A15 compounds A 1−β B β , the relation ρ o versus β exhibits a 'universal' behavior: the effect of the chemical nature of the constituents on ρ o is negligible. The slopes of ρ 0 versus the Ti, Ga and Ni contents in the A15 layer coincide and are much steeper than for the Ta additive, corresponding to the three times higher number of 6c sites with respect to 2a A15 lattice sites.The presence of two grain morphologies, e.g. equiaxial and columnar, is observed in Nb 3 Sn wires produced by the bronze route only. The nonlinearity of the Kramer plot in multifilamentary Nb 3 Sn bronze route wires is explained by the presence of these two different grain types, which have distinctly different Sn contents and sizes. For these wires, the total pinning force can be represented as the superposition of two contributions with different scaling fields.Simultaneous addition of different additives on 'in situ' Fe/MgB 2 wires is presented as an attempt to combine different possible mechanisms influencing J c . The substitution of boron by carbon is known to enhance the value of ρ o and thus of the critical field. In addition, the pinning behavior is expected to be improved by grain boundary effects or nanosize precipitations, caused by the presence of appropriate additives during the MgB 2 phase formation. Since the two mechanisms are independent, their effect on J c is expected to be cumulative. In the present paper, the results on the additive combination B 4 C + LaB 6 in monofilamentary Fe sheathed MgB 2 wires are reported. The data are compared with the additives B 4 C + SiC and show that simultaneous additives could be promising in view of applications at 20 K.

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“…Ti and Ta are presently the most widely used additive elements for doping Nb 3 Sn wires. Recent work shows a further enhancement of J c by substituting the combination of Ti + Ta [26].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of the critical current density and upper critical field in Zr and Mo co-doped Nb₃Sn

He¹,

Dong²,

Cao³

et al. 2009

Supercond. Sci. Technol.

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We prepared a series of Nb 3−2x Zr x Mo x Sn (0 x 0.2) samples which have the same number of electrons per cell as Nb 3 Sn in order to study the doping effect. The formation of the single phase samples was confirmed by x-ray diffraction when x 0.1. It was found that the lattice parameters a decrease slightly with the increasing dopant concentration. The grain morphologies of the sample are irregular. As the dopant content increases, the size of the coarse grain decreases and the content of the fine grain increases. The T c value of the Nb 3−2x Zr x Mo x Sn samples drops slowly when x < 0.1, whereas a sharp decline of T c occurs when x > 0.1. The T c drop in the co-doped samples is slower than that in the single-doped ones with the same total dopant concentrations, indicating that the N(E F ) plays an important role in the change of T c . At 4 T and 10 K, the J c value of Nb 2.8 Zr 0.1 Mo 0.1 Sn sample reached 3.4 × 10 6 A cm −2 , which is significantly enhanced by more than 400 and 23 times that of the pure Nb 3 Sn and single-doped Nb 2.8 Mo 0.2 Sn samples, respectively. The H c2 (0) values of the co-doped sample are higher than the pure and single-doped sample. The H c2 (0) value of the Nb 2.8 Zr 0.1 Mo 0.1 Sn sample reached 30 T.

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Investigation on the Effect of Ta Additions on $J_{c}$ and $n$ of $({\rm Nb},{\rm Ti})_{3}{\rm Sn}$ Bronze Processed Multifilamentary Wires at High Magnetic Fields

Cited by 9 publications

References 14 publications

Thermal Conductivity of Industrial $\hbox{Nb}_{3} \hbox{Sn}$ Wires Fabricated by Various Techniques

Thermal Conductivity of Industrial $\hbox{Nb}_{3} \hbox{Sn}$ Wires Fabricated by Various Techniques

Optimization of Nb₃Sn and MgB₂wires

Enhancement of the critical current density and upper critical field in Zr and Mo co-doped Nb₃Sn

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Investigation on the Effect of Ta Additions on $J_{c}$ and $n$ of $({\rm Nb},{\rm Ti})_{3}{\rm Sn}$ Bronze Processed Multifilamentary Wires at High Magnetic Fields

Cited by 9 publications

References 14 publications

Thermal Conductivity of Industrial $\hbox{Nb}_{3} \hbox{Sn}$ Wires Fabricated by Various Techniques

Thermal Conductivity of Industrial $\hbox{Nb}_{3} \hbox{Sn}$ Wires Fabricated by Various Techniques

Optimization of Nb3Sn and MgB2wires

Enhancement of the critical current density and upper critical field in Zr and Mo co-doped Nb3Sn

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Optimization of Nb₃Sn and MgB₂wires

Enhancement of the critical current density and upper critical field in Zr and Mo co-doped Nb₃Sn