Nb芯增强千米级7芯MgB_2超导线材的机械性能及超导性能研究

Mechanical and superconducting properties of kilometer level,Nb reinforced,6+1 filamentary MgB_2wires

以非铁磁性的Nb作为中心增强体和阻隔层材料,无氧铜作为稳定体包套材料,采用原位法粉末装管工艺(in-situ PIT)制备了千米量级6+1芯导体结构的MgB2/Nb/Cu超导线带材,由于Nb/Cu包套材料具有良好的塑形加工性能,整个加工过程中未进行中间退火热处理,复合多芯线材最终加工到Φ1.4mm;在真空热处理炉中680℃保温2小时进行成相热处理;对烧结后的线材进行了超导电性、纵向电流分布均匀性及弯曲及拉伸力学性能等分析检测。线材的工程临界电流密度在20K,1T磁场条件下达到2.5×104A/cm2,表明该工艺能够制备实用化高性能的MgB2线带材。

Kilometer level 6 ＋ 1 filamentary MgB2 wires sheathed with Nb/Cu composite tube was fabricated by in - situ pow- der - in - tube （PIT） method, non - magnetic Nb was employed as the centre reinforced materials. There was no any annealing in the whole fabrication process due to the excellent ductility of Nb/Cu composite tube. The （Mg, B）/Nb/Cu composite wire was fabricated to the target size of 1.4 mm in diameter and heat treated at 680℃ for 2 hours in a vacuum furnace. Superconductivity, mechanical properties and homogeneity of critical current were measured respectively. The transport engineering critical current density （Jc~） reaches 2.5 ×104 A/cm2 at 20K, 1T. The results show a good potential to fabricate high performance MgB2 wires at ambient pressure for practical application.