Increased Superconducting Critical Current Density in Internal Tin Niobium-Tin (Nb3Sn) Composite Wires by Magnesium Doping

  • J. C. McKinnell
  • M. B. Siddall
  • P. M. O’Larey
  • D. B. Smathers
Part of the An International Cryogenic Materials Conference Publication book series (ACRE, volume 40)

Abstract

Requirements for AC superconducting machines such as ITER, MagLev, and power applications continue to drive the development of superconducting wires. There are several challenges in producing wire with good properties for AC applications. Nb-Ti composite wires have been manufactured with sub-micron filaments, often at the cost of a significant reduction in the critical current density (Jc).1 For Nb3Sn wire, the physical filament diameter (d) is often much smaller than the effective filament diameter (deff) due to coupling of the filaments during the reaction heat treatment. Filament coupling causes significant increases in the cooling load per cycle relative to uncoupled filaments. The increase in power dissipation per cycle may affect the magnet stability and in the case of cable in conduit conductors it may shorten the length of cable cooled by a single helium inlet.

Keywords

Critical Current Density United States Patent Electromagnetic Test Composite Wire Nb3Sn Layer 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    I. Hlasnik, et al., “Properties of superconducting NbTi superfine filament composites with diameters _0.1 µm,” Cryogenics, 25: 558 (1985).CrossRefGoogle Scholar
  2. 2.
    W.K. McDonald, “Composite construction process and superconductor produced thereby,” United States Patent #4, 262, 412 (1981).Google Scholar
  3. 3.
    W.K. McDonald, “Expanded metal containing wires and filaments,” United States Patent #4, 414, 428 (1983).Google Scholar
  4. 4.
    D.B. Smathers, “Process for making filamentary superconductors using tin-magnesium eutectics,” United States Patent #4973527 (1990).Google Scholar
  5. 5.
    D.B. Smathers, “Alloy core modifications for tin core superconducting materials,” United States Patent #5098798 (1992).Google Scholar
  6. 6.
    D.B. Smathers, Al5 superconductors, in:“Metals Handbook,” volume 2, 10th edition, ASM International (1990).Google Scholar
  7. 7.
    K. Togano, T. Asano, K. Tachikawa, “Effects of magnesium addition to the Cu-Sn matrix in the composite processed Nb3Sn superconductor,” J. Less Common Metals, 68: 15 (1979).CrossRefGoogle Scholar
  8. 8.
    I.W. Wu, et al., “The influence of magnesium addition to the bronze on the critical current of bronze-processed multifilamentary Nb3Sn,” IEEE Trans. Mag., Mag-19: 1437 (1983).Google Scholar
  9. 9.
    T. Kuroda, et al., “Internal-tin-processed Nb3Sn multifilamentary wires alloyed with Mg, Zn + Ti, and Tithrough the Sn core,” Adv. Cryo. Eng. Matt., 32: 1108 (1986).Google Scholar
  10. 10.
    I.W. Wu, et al., “Critical current density of bronze-processed multifilamentary Nb3Sn wires with magnesium addition to the matrix,” App. Phys. Let., 45: 792 (1984).Google Scholar
  11. 11.
    J.Q. Xu, et al., “Superconducting and metallurgical properties of Nb3Sn wires processed by internal tin route including hydrostatic extrusion,” Cryogenics, 29: 87 (1989).CrossRefGoogle Scholar
  12. 12.
    A. Borsese, et al., “Heat of formation of magnesium-tin alloys,” Zeitschrift fur Metallkunde, 66: 226 (1975).Google Scholar
  13. 13.
    M.B. Siddall and D.B Smathers, “Method for critical current testing: software corrections,” IEEE Trans. Mag., Mag-25: 1823 (1989).Google Scholar
  14. 14.
    M. Hansen, “Constitution of Binary Alloys,” McGraw-Hill Book Company, New York (1958).Google Scholar
  15. 15.
    J. Ellmer, et al., “On the liquidus in tin-rich Sn-Mg alloys,” Met. Trans., 4: 889 (1973).Google Scholar
  16. 16.
    J.W. Ekin, “Effect of uniaxial strain on Nb3Sn with Mg additions,” NBS-IR, 86–3044: 30 (1986).Google Scholar
  17. 17.
    Y.A. Chang, et al. “Phase Diagrams and Thermodynamic properties of ternary copper-metal systems,” International Copper Research Association, Inc. (1979).Google Scholar
  18. 18.
    D.B. Smathers, et al., “Properties of idealized designs of Nb3Sn composites,” IEEE Trans. Mag., Mag-21: 1133 (1985).Google Scholar
  19. 19.
    K.R. Marken, et al., “Characterization studies of a fully reacted high bronze to niobium ratio filamentary Nb3Sn composite,” Adv. Cryo. Eng. Mati., 32: 967 (1986).CrossRefGoogle Scholar
  20. 20.
    K.R. Marken, “Characterization Studies of Bronze-Process Filamentary Nb3Sn Composites,” Ph.D. Thesis, University of Wisconsin-Madison (1986).Google Scholar
  21. 21.
    K. Tachikawa, et al., “Composite processed V3Cu with improved current-carrying capacities in high magnetic fields,” IEEE Trans. Mag., Mag-15: 391 (1979).Google Scholar

Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • J. C. McKinnell
    • 1
  • M. B. Siddall
    • 1
  • P. M. O’Larey
    • 1
  • D. B. Smathers
    • 1
  1. 1.Teledyne Wah Chang-AlbanyAlbanyUSA

Personalised recommendations