The Effect of Filament Diameter on ${\rm J}_{\rm e}$ in High Filament Count Bi2212/Ag Round Wire

Nachtrab, W.T.; Wong, Terence Kin Shun; Liu, X.T.; Schwartz, J.

doi:10.1109/tasc.2009.2018213

Cited by 12 publications

(8 citation statements)

References 23 publications

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“…While both Ag/Mg and Ag/Al can be produced in the DS condition by similar approaches, Al 2 O 3 has a higher elastic modulus and lower coefficient of thermal expansion (CTE) than MgO. Additionally, previous research has shown that Al 2 O 3 is relatively inert to Bi2212 and does not react strongly with the ceramic fiber used to insulate the conductor [42]. Lastly, Al is inexpensive and readily available [36,42].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, previous research has shown that Al 2 O 3 is relatively inert to Bi2212 and does not react strongly with the ceramic fiber used to insulate the conductor [42]. Lastly, Al is inexpensive and readily available [36,42]. In the most recent report, Ag/0.5 wt%Al metal powder, which was oxidized at 675 • C in flowing pure oxygen, was used to form the DS Ag/0.5 wt%Al alloy.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

Kajbafvala¹,

Nachtrab²,

Kumar³

et al. 2013

Supercond. Sci. Technol.

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High strength dispersion strengthened (DS) Ag/Al alloys with various Al content are studied as candidates for sheathing Bi 2 Sr 2 CaCu 2 O 8+x (Bi2212) wire. The Ag/Al alloys are fabricated by powder metallurgy and internally oxidized in pure oxygen. The time and temperature of the internal oxidation heat treatment is varied to maximize the strength after undergoing the Bi2212 partial melt process (PMP). Vickers micro-hardness number (HVN), room temperature tensile behavior, optical and scanning electron microscopy, ion channeling contrast imaging using a focused ion beam and electrical resistivity measurements are used to characterize the alloys. An Ag/0.2wt%Mg (Ag/Mg) alloy is used for comparison. Results show that internal oxidation at 650-700 • C for 4 h produces the highest HVN for the DS Ag/Al alloy; when oxidized at 675 • C for 4 h the HVN, yield strength and tensile strength of the DS Ag/Al are 50% higher than the corresponding values of Ag/Mg. Microstructural observations show that Al 2 O 3 precipitates play the main role in strengthening the DS Ag/Al alloy. The alloy retains its fine grain structure and strength after PMP heat treatment.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

Kajbafvala¹,

Nachtrab²,

Kumar³

et al. 2013

Supercond. Sci. Technol.

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“…Ag-alloy sheathed Bi 2 Sr 2 CaCu 2 O x (Bi2212) superconductors produced via the powder-in-tube (PIT) process are promising for low temperature, high magnetic field applications and there is a significant effort to improve the critical current density (J c ) in round wires [1][2][3][4][5][6][7][8][9][10]. At present, Bi2212 wires are primarily heat treated using the partial melt process (PMP), which consists of heating the wire above its peritectic melt temperature, cooling to a temperature below T solidus , and isothermal annealing for an extended period [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Influencing factors on the electrical transport properties of split-melt processed Bi₂Sr₂CaCu₂O_xround wires

Liu

Schwartz

2012

Supercond. Sci. Technol.

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Here we study the effects of varying split-melt processing (SMP) heat treatment temperatures on multifilamentary Bi 2 Sr 2 CaCu 2 O x (Bi2212) wires to understand the factors that influence the electrical transport properties. Sharp threshold behaviors result in an order-of-magnitude difference in critical current density and distinct difference in magnetization behavior. Quantitative image analysis of SEM micrographs shows a strong correlation between the content of 2-4 µm interfilamentary bridges and electrical performance. Avrami analysis of re-solidification indicates that Bi2212 grain nucleation is heterogeneous and site-saturation limited, with a transition in the reaction mechanism corresponding to the depletion of liquid. During the first SMP heat treatment, oxygen is fully recovered, accelerating Bi2201 and/or Bi2212 phase nucleation. Large, flat Bi2201 grains form from the Bi2201 liquid at the start of the second heat treatment and subsequently act as Bi2212 grain nucleation sites. During cooling from high temperature, Bi2212 grains form via a solid/liquid reaction that is enhanced by the liquid, that facilitates second phase dissolution and cation diffusion. At lower processing temperatures, and when the liquid is depleted, Bi2212 grain growth is from a slow solid-state reaction.

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“…References [8]- [11] have shown that, because of the increased interface area which promotes greater c-axis texture, generally, increases with decreasing filament diameter up to a point, suggesting that there is an optimum filament size based on geometry. Reference [10] also suggests that the peak melt processing temperature must be adjusted for wire diameter and filament size to maximize .…”

Section: Introductionmentioning

confidence: 99%

Transport, Magnetic, and SEM Characterization of a Novel Design Bi-2212 Strand

Myers

Susner

Motowidlo

et al. 2011

IEEE Trans. Appl. Supercond.

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In this work, a new strand design for Bi-2212 conductors was studied. The new design had a single stack approach with randomly oriented but densely packed two-dimensional Bi-2212 filaments. This Bi-2212 Two-Dimensional Random-Oriented Single-Stack (2D-ROSS) Round Wire design led to high levels of grain texture and significant amounts of Ag-superconductor interface within the filaments, while maintaining a high strand fill factor. This new design was compared to a strand made with a conventional billet layout. Heat treatments were performed under 100% flowing oxygen, and the samples were melt processed at 884, 886, 888, and 891 C. The strands were studied via transport, magnetic, and electron optics techniques. The strands manufactured with the new process showed higher critical currents than the standard design strands in terms of engineering critical current density ( ) but slightly lower layer critical current density ( ). However both strand sets were limited by filament sizes whichwere not yet optimized and excessive C-content in the powders. values of 48 A mm 2 for the new strand design, and 26 A mm 2 for the conventional double stack design, at 12 T and 4.2 K were observed. An interesting property of the new strand method was that the strands were less sensitive to small heat treatment, HT, temperature variations in terms of their final properties. Magnetic and microstructure/phase assemblage studies observed less filament bridging in the new strand design as compared to the conventional one.

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The Effect of Filament Diameter on ${\rm J}_{\rm e}$ in High Filament Count Bi2212/Ag Round Wire

Cited by 12 publications

References 23 publications

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

Influencing factors on the electrical transport properties of split-melt processed Bi₂Sr₂CaCu₂O_xround wires

Transport, Magnetic, and SEM Characterization of a Novel Design Bi-2212 Strand

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The Effect of Filament Diameter on ${\rm J}_{\rm e}$ in High Filament Count Bi2212/Ag Round Wire

Cited by 12 publications

References 23 publications

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi2Sr2CaCu2O8+xround wire

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi2Sr2CaCu2O8+xround wire

Influencing factors on the electrical transport properties of split-melt processed Bi2Sr2CaCu2Oxround wires

Transport, Magnetic, and SEM Characterization of a Novel Design Bi-2212 Strand

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Product

Resources

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High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

Influencing factors on the electrical transport properties of split-melt processed Bi₂Sr₂CaCu₂O_xround wires