The Bronze Processed Nb3Sn Ultra-Thin Superconducting Wires
The Bronze Processed Nb3Sn Ultra-Thin Superconducting Wires
复制标题
青铜加工Nb3Sn超细超导线材
DOI：
10.1109/tasc.2022.3145286
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发表时间：
2022
影响因子：
1.8
通讯作者：
M. Otsubo
中科院分区：
文献类型：
--
作者：
A. Kikuchi;Y. Iijima;M. Yamamoto;Masahiko Kawano;M. Otsubo
我们研究了青铜工艺制备Nb<sub>3</sub>Sn超细丝。起始坯料由19根铌棒、Cu-14mass%Sn-0.3mass%Ti的青铜合金基体、铌扩散阻挡层和最外层的Cu稳定剂组装而成。 Cu/非Cu比率设计为0.89。规定坯料的外径为45.2毫米。以9.1的挤压比进行热挤压后，采用卷对卷工艺将其直径从15.0毫米冷拉至0.05毫米（50微米），并进行中间退火。最终，我们获得了超过 7,000 m 的单片长度且没有断线。此外，我们还演示了使用 50 微米 Nb<sub>3</sub>Sn 线的 7 和 7/7 绞合电缆。初级 7 和次级 7/7 绞合电缆在 4.2 K 和 4 T 时的传输临界电流 I</italic><sub>c</sub> 分别为 14.2 A 和 102.0 A。单根超细导线在 4.2 K 和 4 T 下的 <italic>I</italic><sub>c</sub> 电流为 2.04 A，因此，7 和 7/7 绞合电缆的 <italic>I</italic><sub>c</sub> 测量值几乎等于单根导线的 <italic>I</italic><sub>c</sub> 计算值。此外，我们还研究了使用不同半径的黄铜夹具对次级 7/7 绞合电缆 <italic>I</italic><sub>c</sub> 的弯曲效果。同时，我们研究了弯曲前焊料浸渍的效果。具有焊料浸渍的 7/7 绞合电缆的 <italic>I</italic><sub>c</sub> 在 11.5 mm 的半径上弯曲后表现出显着的退化。但没有焊料浸渍的电缆的<italic>I</italic><sub>c</sub>却没有。
We have studied the fabrication of Nb<sub>3</sub>Sn ultra-thin wire through the bronze process. The starting billet was assembled by 19 Nb rods, a bronze alloy matrix of Cu-14mass%Sn-0.3mass%Ti, Nb diffusion barrier, and the outermost Cu stabilizer. The Cu/non-Cu ratio was designed as 0.89. The outer diameter of the stating billet is 45.2 mm. After the hot extrusion with an extrusion ratio of 9.1, it was cold-drawn from 15.0 mm to 0.05 mm (50 microns) in diameter with intermediate annealing with reel-to-reel process. Eventually, we have obtained over 7,000 m in a piece length without wire-breakages. In addition, we have also demonstrated both 7 and 7/7 stranded cables using 50 microns Nb<sub>3</sub>Sn wire. The transport critical current, <italic>I</italic><sub>c</sub>, at 4.2 K and 4 T of both the primary 7 and the secondary 7/7 stranded cables were 14.2 A 102.0 A, respectively. A single ultra-thin wire showed 2.04 A of <italic>I</italic><sub>c</sub> at 4.2 K and 4 T, thus, measured <italic>I</italic><sub>c</sub> values of 7 and 7/7 stranded cables become almost equivalent to the calculated values from the <italic>I</italic><sub>c</sub> of a single wire. In addition, we investigated the bending effect on <italic>I</italic><sub>c</sub> of the secondary 7/7 stranded cable using the brass fixtures having a different radius. Meantime, we studied the effect of solder impregnation before bending. The <italic>I</italic><sub>c</sub> of 7/7 stranded cable with solder impregnation showed a dramatic degradation by bending on the radius of 11.5 mm. But the <italic>I</italic><sub>c</sub> of the cable without solder impregnation did not.