7芯复合包套Ba1-xKxFe2As2线带材的显微结构与超导性能研究

Microstructure and superconducting properties of 7-filament Ba1-xKxFe2As2 composite conductors

摘要:

传统Ag包套与铁基超导材料具有良好的化学相容性以及塑性加工特性，但是其机械强度低；而采用复合包套来制备高强度Ba1-xKxFe2As2铁基多芯线带材是一种直接高效且成本低廉的方法。本研究选取高强度高延展性的Ag/Nb/Cu三层复合包套，从线带材包套尺寸、冷加工工艺和中间退火等方面进行优化，获得了结构稳定且易于加工的Ba1-xKxFe2As2多芯线带材。Ag/Nb/Cu复合包套Ba1-xKxFe2As2线带材的多芯孔型完整并且分布均匀，超导填充因子约为25.3-28.0%，并且具有较好的力学性能。Ba1-xKxFe2As2多芯带材的转变Tc为37.5 K，M-H曲线表明样品具有较强的内在磁通钉扎能力。在4.2 K和2 T下其传输Jc约为1.0×104 A/cm2，在10 T时传输Jc仍然保持为8.7×103 A/cm2。

Abstract:

The traditional Ag sheath has both good chemical compatibility and plastic processing characteristic with iron-based superconductors (IBS), but it possesses too low mechanical strength. Employing composite sheathes is a direct, efficient and low-cost method to prepare high strength Ba1-xKxFe2As2 conductors. In this paper, the Ba1-xKxFe2As2 multifilamentary wires/tapes with stable structure and large ductility were obtained through optimizing the sheath size, cold deformation and intermediate annealing. It is found that the shape distribution of multi-cores is uniform, and the superconducting filling factor is about 25.3-28.0% for our Ag/Nb/Cu composite sheathed Ba1-xKxFe2As2 superconductors. The magnetic critical transition temperature Tc of Ba1-xKxFe2As2 tape is up to 37.5 K, meanwhile the magnetization of hysteresis loops (M-H) shows a strong flux pinning ability. The transport critical current density Jc of Ba1-xKxFe2As2 tape is about 1.0×104 A/cm2 at 4.2 K and 2 T, and still holds 8.7×103 A/cm2 at 10 T.