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Correlation between mesoscopic mechanical behavior and superconductivity for multifilamentary superconducting composite wire

多丝超导复合线细观力学行为与超导性的相关性

基本信息

批准号：
13650088
负责人：
HOJO Masaki
金额：
$ 2.69万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650088/
关键词：
Superconducting wire Composite materials Nb-Ti Nb_3Sn Thermal residual stress Fatigue loading Critical current Damage of filament Nb3Sn

项目摘要

Deformation and fracture of superconducting filaments and matrix copper were investigated for multifilamentary Nb-Ti/Cu and Nb3Sn/Cu superconducting composite wires. The researches were conducted from the mesoscopic view point, and the complicated thermal residual stresses were taken into account. Then the correlation between the deformation and superconductivity were studied. The results are summarized as follows:(1) Mechanical properties of Cu and Cu-Sn in Nb_3Sn/Cu composite wires:The copper component was removed from the Nb_3Sn/Cu/Cu-Sn/Nb composite wire, and comparison of the stress-strain curves with and without copper component yielded the stress-strain curves of the copper and bronze component. In addition to these detailed experimental procedures, the non-uniformity of the thermal residual stress in copper phase was taken into account in the present study. In order to confirm the strain distribution in copper phase, the test was carried out with the composites from which half … More amount of copper was removed.(2) Mechanical properties of Nb3Sn filaments in Nb_3Sn/Cu composite wires:The Nb_3Sn filaments were extracted from the composite wire with nitric acid, and then impregnated with epoxy resin. The Young's modulus of Nb_3Sn filament was calculated using the rule of mixture. The results indicated that the Young's modulus of Nb_3Sn filament was smaller than already reported values.(3) Microscopic fatigue fracture process in Nb-Ti/Cu composite wires:Fatigue cracks initiated at the surrounding stabilizer copper, and went through the transverse section of the wire, cutting Nb-Ti filaments. Both the residual, strength of fatigued wire and the critical current after fatigue loading were well correlated to the number of remaining filaments.(4) Multiple necking of filaments in Nb-Ti/Cu composite wires:The effect of mechanical properties of Nb-Ti wire and copper on the formation of multiple necking was investigated by changing the annealing temperature up to 500℃. For higher annealing temperature, the yield stress of copper decreased and extensive work hardening was observed. At the annealing temprature of 500℃, the multiple necking. was experimentally observed. This behavior was also confirmed by the numerical deformation analysis using finite element method. Less

研究了多芯Nb-Ti/Cu和Nb_3Sn/Cu超导复合线中超导丝和母材铜的变形和断裂。研究从细观角度出发，考虑了复杂的热残余应力。然后研究了形变与超导电性之间的关系。主要研究结果如下：(1)Nb_3SN/Cu复合丝中铜和铜-锡的力学性能：从Nb_3SN/Cu/Cu-Sn/Nb复合丝中去除铜组分，对比有无铜组分的应力-应变曲线，得到了铜和青铜组分的应力-应变曲线。除了这些详细的实验步骤外，本研究还考虑了铜相中热残余应力的不均匀。为了确定应变在铜相中的分布，用半…的复合材料进行了试验Nb_3SN/Cu复合丝的力学性能：用硝酸从复合丝中提取Nb_3SN丝，然后用环氧树脂浸渍。用混合法计算了Nb3Sn丝的杨氏模数。(3)Nb-Ti/Cu复合线材的微观疲劳断裂过程：疲劳裂纹从周围的稳定剂铜开始，穿过线材的横截面，切割Nb-Ti线材。线材疲劳后的剩余量、疲劳强度和疲劳加载后的临界电流都与剩余丝的数量有很好的相关性。(4)Nb-Ti/Cu复合丝的多颈缩：通过改变热处理温度至500℃，研究了Nb-Ti丝和铜的力学性能对多颈缩形成的影响。退火温度越高，铜的屈服应力越低，加工硬化越明显。在500℃的热处理温度下，出现多次颈缩现象。是通过实验观察到的。有限元数值变形分析也证实了这一点。较少