Superconducting Properties of Nb3Al Multifilamentary Wires Fabricated Continuously by Rapid-Quenching
Recently we developed a new fabrication process of Nb3Al multifilamentary wire, in which Nb/Al-5at%Mg multifilamentary composite wires were rapidly heated and rapidly quenched to obtain composite wires including many Nb-Al supersaturated bcc filaments. Then the resulting composites were annealed to form Nb3Al filaments through the deposition from the metastable Nb-Al bcc filaments. When the Al-5at%Mg alloy core diameters were about 0.6 μm, the wire showed the highest Tc and the highest Jc (20 T, 4.2 K) of 17.4 K and 2.5 × 108 A/m2, respectively. The optimized Jc values in high fields are much higher than those of the commercially available (Nb,Ti)3Sn multifilamentary wires. Small mechanical deformation (bending, twisting, and stranding) of the as-quenched composite wires did not degrade the superconducting properties of the final Nb3Al multifilamentary wires, which proves the good ductility of the supersaturated bcc filaments. Therefore it should not be difficult to fabricate a large-scaled Nb3Al stabilized conductor due to easy handling of as-quenched composite during the fabrication processes, such as Cu-plating, stranding, Cu-housing, and/or encasing into conduit. The final annealing can be performed after these processes. It seems to be possible to make superconducting magnets of this Nb3Al wire through the wind & react method. Jc valus of various parts cut from a long wire showed a variation of about ±15 %.
KeywordsHeating Power Superconducting Property Good Ductility Filament Diameter Composite Wire
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