Materials Transactions Online

Transactions of the Japan Institute of Metals, Vol. 26 No. 9 (1985) pp.663-671
© 1985 The Japan Institute of Metals

Effects of Zr, Hf and Ta Additions on Properties of in situ Cu-20%Nb-Sn Superconductors

Akihiko Nagata*, Kazuhiko Hayashi**, Toru Hanano***
and Osamu Izumi*

Improvements of high-field properties of in situ Nb3Sn superconductors were studied by additions of 2%Zr, 2%Hf and 2%Ta to Cu-20 mass%Nb melts. The eutectic structures around Nb dendrites were observed in all as-cast materials, and some difficulties arose from the structures in drawing the ingots with Zr and Hf into wires. The critical current densities were measured up to 15 T after various heat treatments.
Additions of Zr and Hf affected a little Jc in the high magnetic field region and HC2* of in situ Cu-2O%Nb-Sn superconductors. On the contrary, additions of Ta improved appreciably the high-field performance of in situCu-20%Nb-Sn superconductors in spite of the fact that Ta was not soluble in the Nb dendrites in the as-cast state. The highest Jc of (1-2)×108 A/m2 at 12 T and HC2* of 17.5 T were obtained on the in situ Cu-20%Nb-2Ta-Sn superconductors.

(Received February 22, 1985)

Keywords: in situ Nb3Sn superconductor, Nb3Sn superconductor, copper-niobium alloy, critical current density, zirconium, hafnium, tantalum, in situ superconducting composite


* The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai 980, Japan.

** Graduate Student, Tohoku University, Sendai. Present address: Sumitomo Electric Industries, Ltd., Osaka 554, Japan.

*** Graduate Student, Tohoku University, Sendai. Present address: Tore Shiga, Tore Co. Ltd., Ohtsu 520, Japan.

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© 1985 The Japan Institute of Metals