Abstract
The authors have studied the phase formation sequences in a Nb3Sn ‘internal tin’ process superconductor. Heat treatments were performed to convert the starting materials of tin, Ti–Sn, copper and niobium, to bronze and Nb3Sn. Specimens were quenched at different points of the heat treatment, followed by metallography to identify the phases present and X-ray microtomography (XMT) to investigate the void volume and distribution. An unexpected observation of the microstructure development was the uphill diffusion of tin during the Cu–Sn reactive diffusion. Some defects likely to affect the superconducting performance of the wires were observed. Microscopy revealed the presence of a Ti–Sn intermetallic compound displacing the niobium filaments, and XMT revealed the formation of long pores in the longitudinal direction. Two types of pore formation mechanism, in addition to Kirkendall pores, are proposed. The phase and microstructure development suggests that low-temperature heat treatment (below 415 °C) will have significant influence on optimising the final superconducting properties.
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Yoshizaki K, Taguchi O, Fujiwara F, Imaizumi M, Wakata M, Hashimoto Y, Wakamoto K, Yamada T, Satow T (1983) IEEE Trans Magn 19:1131
Fischer CM, Lee PJ, Larbalestier DC (2002) In: Advances in cryogenic engineering, vols 48a and b; vol 614, p 1008
Kaufmann AR, Pickett JJ (1971) J Appl Phys 42:58
Suenaga M, Klamut CJ, Higuchi N, Kuroda T (1985) IEEE Trans Magn 21:305
Yoshizaki K, Wakata M, Miyashita S, Fujiwara F, Taguchi O, Imaizumi M, Hashimoto Y (1985) IEEE Trans Magn 21:301
Hayase T, Kajihara M (2006) Mater Sci Eng A 433:83
Osamura K, Ochiai S, Kondo S, Namatame M, Nosaki M (1986) J Mater Sci 21:1509
Miyashita S, Yoshizaki K, Hashimoto Y, Sekine H, Tachikawa K (1987) IEEE Trans Magn 23:629
Naka M, Schuster JC, Nakade I, Urai S (2001) J Phase Equilib 22:352
Godeke A (2005) Performance Boundaries in Nb3Sn Superconductors. PrintPartners Ipskamp, Enschede. ISBN 90-365-2224-2
Raynor GV (1944) Annotated equilibrium diagram series: No 2. The Institute of Metals, London
Lefranc G, Muller A (1976) J Less-Common Met 45:339
Tan KS (2006) PhD Thesis, University of Cambridge
Pong I, Hopkins SC, Fu X, Glowacki BA, Elliott JA, Baldini A (2006) Defect Diffus Forum 258–260:294
Muller M, Schulz H, Kirchmayr H (2005) Physica C 419:115
Watson IG, Lee PD, Dashwood RJ, Young P (2006) Metall Mater Trans A 37A:551
Haibel A, Scheuerlein C (2007) IEEE Trans Appl Superconduct 17:34
Scheuerlein C, Oberli L, Michiel D, Reichert K (2006) Voids in Nb3Sn strands observed by synchrotron absorption microtomography. Poster presented at the International Cryogenic Materials Conference, 17–21 July 2006, Prague, Czech Republic
Easton DS, Kroeger DM (1979) IEEE Trans Magn 15:178
Scheuerlein C, Di Michiel M, Haibel A (2007) Appl Phys Lett 90:132510
Dietderich DR, Glazer J, Lea C, Hassenzahl WV, Morris JW (1985) IEEE Trans Magn 21:297
Naus MT, Jewell MC, Lee PJ, Larbalestier DC (2002) In: Advances in cryogenic engineering, AIP conference proceedings, vols 48a and b; vol 614. Amer Inst Physics, Melville, NY, ISBN 0-7354-0060-1, p 1016
Acharya NN (2001) J Mater Sci 36:4779
Darken LS (1949) Trans Am Inst Minerals 180:430
Park H, Lee DN (2003) Metall Mater Trans A 34:531
Dyson BF, Anthony TR, Turnbull D (1967) J Appl Phys 38:3408
Suenaga M, Horigami O, Luhman TS (1974) Appl Phys Lett 25:624
Acknowledgements
Ian Pong would like to thank the Croucher Foundation, Hong Kong, and Simon Hopkins the EPSRC, for financial support.
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Pong, I., Hopkins, S.C., Fu, X. et al. Microstructure development in Nb3Sn(Ti) internal tin superconducting wire. J Mater Sci 43, 3522–3530 (2008). https://doi.org/10.1007/s10853-008-2522-4
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DOI: https://doi.org/10.1007/s10853-008-2522-4