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

对多丝Nb-Ti/Cu和Nb3Sn/Cu超导复合线材的超导丝和基体铜的变形和断裂进行了研究，并考虑了复杂的热残余应力，并进行了相关性分析。研究结果如下:(1)Nb_3Sn/Cu中Cu和Cu-Sn的力学性能。复合线材：将Nb_3Sn/Cu/Cu-Sn/Nb复合线材中的铜成分去除，比较有铜成分和无铜成分的应力应变曲线，另外得到铜成分和青铜成分的应力应变曲线。根据这些详细的实验程序，本研究考虑了铜相中热残余应力的不均匀性，为了确认铜相中的应变分布，对半…的复合材料进行了测试。更多金额(2)Nb_3Sn/Cu复合丝中Nb_3Sn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，用下式计算Nb_3Sn丝的杨氏模量。结果表明，Nb_3Sn细丝的杨氏模量比现有的要小。 (3)Nb-Ti/Cu复合丝的微观疲劳断裂过程：疲劳裂纹在稳定器铜周围萌生，并穿过丝的横截面，切断Nb-Ti细丝的残余物、强度。 (4)Nb-Ti/Cu复合丝中丝材的多次颈缩:Nb-Ti丝和铜的力学性能对疲劳丝材的力学性能的影响通过将退火温度提高到500℃来研究多重颈缩的形成。对于较高的退火温度，铜的屈服应力降低并且观察到广泛的加工硬化。在500℃的退火温度下，实验观察到了多重颈缩。使用有限元方法进行的数值变形分析也证实了这一行为。