Composition Profiles and Upper Critical Field Measurement of Internal-Sn and Tube-Type Conductors

Peng, Xuan; Sumption, M.D.; Dhaka, R.; Bhatia, M.; Tomsic, M.; Gregory, E.; Collings, E. W.

doi:10.1109/tasc.2007.899443

Cited by 11 publications

(14 citation statements)

References 4 publications

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“…First fine grain Nb 3 Sn growth occurs in the presence of a Nb 6 Sn 5 layer. At 675 °C it needs typically 8 h to transform Nb 6 Sn 5 entirely into coarse grain (Nb-Ta) 3 Sn and subsequently only fine grain (Nb-Ta) 3 Sn is formed [11].…”

Section: Nb 3 Sn Formationmentioning

confidence: 99%

“…When measured with the spatial resolution of EDS in the Scanning Electron Microscope (SEM/EDS), the concentration gradient across the Nb 3 Sn layer of state-of-the-art high J c strands is in the order of 0.1 at.%Sn/μm. EDS measurements performed in the Transmission Electron Microscope (TEM/EDS) across individual Nb 3 Sn filaments in Internal Tin (IT) strands [3] show stronger local Sn concentration gradients than those revealed by EDS/SEM measurements. Here we report Sn concentration gradients on a nanometer scale in the A15 phase of a state-of-the-art PIT strand, as determined by TEM/EDS measurements using electron transparent lamellas prepared by the Focused Ion Beam (FIB) technique.…”

Section: Introductionmentioning

confidence: 98%

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Sn concentration gradients in Powder-in-Tube superconductors

Cantoni

Scheuerlein

Pfirter

et al. 2010

J. Phys.: Conf. Ser.

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Section: Nb 3 Sn Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Sn concentration gradients in Powder-in-Tube superconductors

Cantoni

Scheuerlein

Pfirter

et al. 2010

J. Phys.: Conf. Ser.

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“…In order to increase the number of subelements above 217, we increased the size of the tube used for the restack from 19 mm (3/4 ) to 38.1 mm (1.5 ) [7]. In an effort to reduce further, we made a 396 subelement restack, denoted as T1692.…”

Section: Results On Strands With Low Arraysmentioning

confidence: 99%

“…Supergenics I LLC and Hyper Tech Research Inc. have explored several approaches including a tube approach [7]- [9]. In order to produce a strand that is stable over a wide field range, we have concentrated our research on lowering the effective filament diameter .…”

Section: Introductionmentioning

confidence: 99%

Strain and Magnetization Properties of High Subelement Count Tube-Type ${\rm Nb}_{3}{\rm Sn}$ Strands

Peng

Gregory²,

Tomsic

et al. 2011

IEEE Trans. Appl. Supercond.

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A tubular technique for economical production of Nb 3 Sn material with large numbers of subelements is being explored by Supergenics I LLC and Hyper Tech Research Inc. The number of subelements was increased to 919 (744 subelements plus 175 Cu filaments) by increasing the size at which restacking is carried out. The product exhibited no fabrication problems and was drawn down and tested at a wire diameter of 0.42 mm, where the subelements are 10 m in diameter. Recently we increased the subelement number to 1387 (1248 subelements plus 139 Cu filaments), which gives a subelement size of 12 m in 0.7 mm diameter wires.Heat treatment (HT) of different subelement restacks has been investigated, and the best results of critical current and stability are presented. The strain tolerance of the strands with 192 and 744 subelements was also tested, and the strand with fine subelement size showed a high intrinsic irreversible strain limit.Index Terms-Axial strain, irreversible strain limit, low loss, Nb 3 Sn superconductor, tube approach.

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“…From figure 4 it can be seen that within experimental error the Sn concentrations in Tube type and RIT strands are more or less the same (note that for RIT strands the EDS spots were located at the centers of the original filaments which could result in a slight underestimation of the Sn content because of a Sn content gradient within this region [20]). The average Sn concentrations, which were calculated by averaging the Sn concentrations of different positions in the FG layer, of EG36-91Re-650x50 and T1489-615x480 are 22.7 at.% and 23.0 at.%, respectively.…”

Section: Stoichiometry and Grain Size Analysismentioning

confidence: 94%

Critical current densities and microstructures in rod-in-tube and tube type Nb₃Sn strands—present status and prospects for improvement

Sumption

Bhartiya

et al. 2013

Supercond. Sci. Technol.

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In this work, the transport and magnetization properties of distributed-barrier Rod-inTube (RIT) strands and Tube Type strands are studied. While Tube Type strands had smaller magnetizations and thus better stabilities in the low field region, their 12 T non-Cu J c s were somewhat smaller than those of the RIT strands. Microstructures were investigated in order to find out the reasons for the difference in non-Cu J c values. Their grain size and stoichiometry were found to be comparable, leading to similar layer J c s. Accordingly it was determined that the lower A15 area fraction rather than the quality of A15 layer was the cause of the discrepancy in non-Cu J c . Subsequently, the area utilizations of subelements were investigated. While for a RIT strand the fine grain (FG) A15 area occupies ~60% of a subelement, for a Tube Type strand it is no more than 40%. Further analysis indicates that the low FG area fraction in a Tube Type strand is attributed to its much larger unreacted Nb area fraction. Finally, a simple change in strand architecture is proposed to reduce the unreacted Nb area fraction.

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Composition Profiles and Upper Critical Field Measurement of Internal-Sn and Tube-Type Conductors

Cited by 11 publications

References 4 publications

Sn concentration gradients in Powder-in-Tube superconductors

Sn concentration gradients in Powder-in-Tube superconductors

Strain and Magnetization Properties of High Subelement Count Tube-Type ${\rm Nb}_{3}{\rm Sn}$ Strands

Critical current densities and microstructures in rod-in-tube and tube type Nb₃Sn strands—present status and prospects for improvement

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Composition Profiles and Upper Critical Field Measurement of Internal-Sn and Tube-Type Conductors

Cited by 11 publications

References 4 publications

Sn concentration gradients in Powder-in-Tube superconductors

Sn concentration gradients in Powder-in-Tube superconductors

Strain and Magnetization Properties of High Subelement Count Tube-Type ${\rm Nb}_{3}{\rm Sn}$ Strands

Critical current densities and microstructures in rod-in-tube and tube type Nb3Sn strands—present status and prospects for improvement

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Product

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Critical current densities and microstructures in rod-in-tube and tube type Nb₃Sn strands—present status and prospects for improvement