Structure of superconducting layers in bronze-processed and internal-tin Nb3Sn-based wires of various designs
Structure of superconducting layers in bronze-processed and internal-tin Nb3Sn-based wires of various designs
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DOI：
10.1063/1.4986232
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发表时间：
2017-06-21
影响因子：
3.2
通讯作者：
Valova-Zaharevskaya, E.
中科院分区：
文献类型：
--
作者：
Deryagina, I.;Popova, E.;Valova-Zaharevskaya, E.
研究了青铜法和内锡法制备的多丝复合材料中Nb3Sn层的微观结构。国际热核实验堆（ITER）型和高j (c)型的IT链比青铜路线的复合材料具有更高的Sn浓度和更高的等轴晶粒比例。在所有样品中，等轴晶的分数与Nb3Sn层中Sn的平均浓度相关。青铜矩阵的钛掺杂bronze-processed电线导致减少平均晶粒尺寸的Nb3Sn谷物和更高的分数更高的Sn的等轴颗粒浓度,从而导致更高的non-Cu J (c)(计算临界电流我比链没有稳定铜)的横截面积,997 a /毫米(2)12 T, 4.2 K,而相同的复合设计与人为Ti-doped Nb细丝。ITER型IT链显示出更高比例的等轴Nb3Sn晶粒，平均晶粒尺寸大得多（120 nm）。与所研究的其他ITER类型链相比，该IT链中的颗粒粗化导致J(c)降低。在具有7个扩展锡源的高J(c)型IT线中，尽管Nb3Sn晶粒尺寸较粗（92 nm），但其等轴晶粒的比例最高（92%），确保了J(c)的最大值。AIP出版社出版。
The microstructure of Nb3Sn layers in multifilamentary composites manufactured by bronze technology and the internal-tin (IT) method differing in the strand design has been studied. The IT strands of International Thermonuclear Experimental Reactor (ITER) type and high-J(c) type are characterized by both the higher Sn concentration and the higher fraction of equiaxed grains than bronze-route composites. In all the samples under study, the fraction of equiaxed grains correlates with the average concentration of Sn in Nb3Sn layers. The Ti doping of the bronze matrix in the bronze-processed wires results in the reduction in average grain sizes of Nb3Sn grains and in a higher fraction of equiaxed grains with a higher Sn concentration, which leads to a higher non-Cu J(c) (calculated as a ratio of critical current I-c to a cross-sectional area of a strand without stabilizing Cu), 997 A/mm(2) at 12 T, 4.2 K, compared to a composite of the same design with artificially Ti-doped Nb filaments. The ITER type IT strand demonstrates a somewhat higher fraction of equiaxed Nb3Sn grains with much larger average grain sizes (120 nm). The grain coarsening in this IT strand results in a decrease in J(c) compared to other ITER type strands studied. The highest values of J(c) are ensured in the high-J(c) type of IT wires with 7 extended tin sources by the highest fraction (92%) of equiaxed Nb3Sn grains despite their coarser sizes (92 nm). Published by AIP Publishing.