摘要
Nb_(3)Sn超导体失超,是超导磁体装备运行过程中的重要现象.失超,即超导体从超导相转变为正常相的过程;在强磁场超导磁体工程中,由于超高的储能密度,失超伴随着力/热/电等物理参量在瞬时的剧烈变化.失超瞬时,超导相转变的同时伴随着弹性力学性能的突变,研究超导相转变时弹性性能的变化是失超诱发应力跨尺度分析的关键.论文首先采用第一性原理方法计算了弹性常数随温度的变化规律,结果表明由于未考虑A15结构的超导材料在环境温度变化的情况下产生的特殊电子能带结构,基于准静态近似方法的材料弹性常数计算从0 K外推至有限温度时,会导致模拟结果与实验观测结果出现定性上的差异;之后,基于晶格自由能函数,给出了描述立方相Nb_(3)Sn单晶弹性性能随温度变化的解析模型,模型预测结果与实验观测结果定性吻合,初步实现了对Nb_(3)Sn单晶超导相转变时弹性性能变化的理论描述和预测.研究结果对于超导体失超应力的跨尺度模拟及超导磁体的安全分析具有一定的理论参考价值.
Quench of a Nb_(3)Sn superconductor is an important phenomenon in the operation of superconducting magnet equipment.It is a transient process, during which the superconductor transforms from the superconducting phase to the normal phase. In the application of Nb_(3)Sn materials in the construction of high-field superconducting magnets, the quench is accompanied by instantaneous drastic changes of mechanical, thermal and electrical parameters because of the high energy storage density.During a quench, the superconducting phase transition is accompanied by abrupt changes of elastic properties of Nb_(3)Sn. The study of those changes is the key to the microscopic and multiscale modeling of the stress arising from the superconducting-normal phase transition. In this paper, the first-principle calculation method is used to calculate the variations of elastic constants with temperature. The results show that because of neglecting the variation of the special electronic band structure of Nb_(3)Sn with ambient temperature, the elastic constants of Nb_(3)Sn, extrapolated from 0 K to the finite temperature based on the quasi-static approximation method, show qualitative difference between the calculation results and the experimental observations. Then, based on the function of lattice free energy, an analytical model is developed to describe the variations of elastic properties of cubic Nb_(3)Sn single crystal with temperature. The model predictions are qualitatively consistent with the experimental results, and an analytical description of elastic properties of Nb_(3)Sn single crystal during superconducting phase transition is given.The results of the study will contribute to the development of modeling and numerical simulation of the stress generated due to quench, and lay a foundation for the safety analysis of superconducting magnets.
作者
杨小敏
杨嘉超
杜侨依
乔力
Xiaomin Yang;Jiachao Yang;Qiaoyi Du;Li Qiao(Institute of Applied Mechanics,College of Mechanical and Vehicle Engineering,Taiyuan University of Technology,Taiyuan,030024)
出处
《固体力学学报》
CAS
CSCD
北大核心
2022年第6期773-782,共10页
Chinese Journal of Solid Mechanics
基金
国家自然科学基金项目(11772212)资助。
