Amorphous superconducting alloys with excellent strength and ductility have been found in rapidly quenched alloys of Nb-Si, Nb-V-Si, Nb-Zr-Si, Nb-Mo-Si, Nb-Ta-Si, Nb-W-Si, Nb-Si-C, Nb-Si-B and Nb-Si-Ge systems. Their continuous ribbons were produced in the form of 1∼ 1.5 mm width and 0.02∼ 0.03 mm thickness by using a modified single roller quenching apparatus. The silicon content in these amorphous alloys was limited to a narrow range between about 17 and 21 at%, and the alloy compositions were in the ranges of 0∼ 20 at%V, 0∼ 25 at%Zr, 0∼ 30 at%Mo, 0∼ 10 at%W, 0∼ 8 at%C, 0∼ 12 at%B and 0∼ 4 at%Ge, respectively. Most of these alloys showed a sharp superconducting transition at a temperature above liquid helium temperature. The transition temperature Tc was in the range of 4.3∼ 4.4 K for Nb79∼ 83Si17∼ 21 alloys. This value increased to 6.7 K after crystallization upon annealing. The addition of Mo, C, B and Ge to the Nb80Si20 alloy brought about a slight increase of Tc and the maximum value was about 5.5 K for Nb50Mo30Si20. The upper critical magnetic field Hc2 and the critical current density Jc were of the order of 2× 106 A/m in liquid helium and of 1× 104 A/cm2 in liquid helium at zero field.
(Received September 26, 1979)
*The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai 980, Japan.
**Hitachi Cable Ltd., Tsuchiura 300, Japan.
© 2002 The Japan Institute of Metals
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