未来聚变堆、加速器等装置要求磁场强度高于15T，甚至高达20T, Nb3Sn等超导材料应用受限。Bi2212超导线材临界性能高，5~30T高场下临界性能几乎无衰减，是各强磁场装置超导磁体首选超导材料之一。但Bi2212超导线材机械性能低，高场下电磁力等负载会引起线材损坏或应变致临界性能衰退，磁体研制需要高强度、高韧性同时具有低热膨胀系数及高导电性能的结构强化材料以强化超导缆。然而，在Bi2212成相热处理中，结构材料的氧化及其与线材元素间的反应将引起线材微结构缺陷，进而导致临界性能衰减。本项目拟采用高性能结构材料与Bi2212超导线材进行超导缆研制模拟，对Bi2212线材在成相热处理过程中形成的缺陷类型及形成机理进行判别，揭示结构材料对线材临界性能影响的微观作用机制，进而提出结构材料的优化方案，为高场用Bi2212超导磁体结构强化材料的研制及高性能Bi2212超导导体和磁体的设计提供参考。

Due to the high critical performance at very high magnetic fields (~30T), Bi2212 round wire is currently considered as a candidate for magnets technology development for the future fusion reactors (CFETR), accelerator and so on. However, Bi2212 is a brittle ceramic material, and the sheath of the round wire is Ag/Ag alloy with high plasticity and low strength. Subjecting to enormous stresses (i.e. electromagnetic stress) during operation under a high field will cause a strain on the round wire and furtherly to decrease its critical performance. The superconductivity stability of Bi2212 magnets can be improved by cabling the Bi2212 wire with high strength materials. Moreover, the oxidation of the high strength material as well as the reactions happened between the Bi2212 wire and the high strength material will affect the Bi2212 formation and cause a decrease in critical performance. So far, researches on the effects of high strength material on critical performance of Bi2212 round wire during heat treatment are seldom carried out and the relevant mechanisms are unclear. In this project, the Bi2212 round wires will be cabled with various high strength materials and heat treated for Bi2212 phase formation. Then the formed defects (like Cu-free particles, voids/bubbles, breaks and so on) together with the critical performance of the wires will be studied. The relevance between the critical performance and the defect type/quantity is expected to be understood. Underlying mechanisms those defects’ formation will be clarified, which will give guidance for high strength material optimization. Besides, these researches will provide basis for higher strength material development that are also compatible with Bi2212. Finally, the results will be a reference for high performance Bi2212 magnets design.