Thermal strain exerted on superconductive filaments in practical Nb3Sn and Nb3Al strands
Thermal strain exerted on superconductive filaments in practical Nb3Sn and Nb3Al strands
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DOI：
10.1088/0953-2048/26/9/094001
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发表时间：
2013-07
影响因子：
3.6
通讯作者：
K. Osamura;S. Machiya;Y. Tsuchiya;H. Suzuki;T. Shobu;M. Sato;S. Harjo;K. Miyashita;Y. Wadayama;Shojiro Ochiai;A. Nishimura
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文献类型：
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作者：
K. Osamura;S. Machiya;Y. Tsuchiya;H. Suzuki;T. Shobu;M. Sato;S. Harjo;K. Miyashita;Y. Wadayama;Shojiro Ochiai;A. Nishimura
实用的超导（SC）线材，例如聚变反应堆中使用的Nb3Sn和Nb3Al绞线，是典型的由脆性超导金属间化合物组成的复合材料。由于组成部件之间的热膨胀系数和弹性模量不同，复合材料中不可避免地会产生热致应变。为了定量评估热应变，利用量子束进行了加热过程中的局部应变测量，并进行了室温拉伸试验。 Nb3Sn 和 Nb3Al 绞线的应力应变曲线均表现出典型的弹塑性行为，可以根据混合物规则进行数值评估。 SC 细丝沿轴向施加的局部应变在室温下为压缩应变，在高温下为拉伸应变，这对于 Nb3Sn 和 Nb3Al 线材来说很常见。通过迭代方法对它们的温度依赖性进行了数值评估。总的来说，已经确定热应变的温度依赖性可以通过此处提出的数值计算很好地再现。指出SC灯丝的热应变受到高于阈值温度的高温下蠕变现象的影响。
Practical superconductive (SC) wires such as the Nb3Sn and Nb3Al strands used in fusion reactors are typical composite materials consisting of brittle superconducting intermetallic compounds. Thermally induced strain is inevitably generated in the composite due to the different coefficients of thermal expansion and different moduli of elasticity among the constituent components. In order to evaluate quantitatively the thermal strain, local strain measurements during heating by means of quantum beams, and room temperature tensile tests were carried out. The stress versus strain curves of both Nb3Sn and Nb3Al strands showed a typical elasto–plastic behavior, which could be numerically evaluated on the basis of the rule of mixtures. The local strain exerted on SC filaments along the axial direction was compressive at room temperature and tensile at high temperatures, which is common for Nb3Sn and Nb3Al strands. Their temperature dependence was numerically evaluated by means of the iteration method. As a whole, it has been established that the temperature dependence of thermal strain can be reproduced well by the numerical calculation proposed here. It is pointed out that the thermal strain in SC filaments is affected by the creep phenomenon at high temperatures above a threshold temperature.