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Nb3Al超导体的超导转变温度(Tc)和上临界磁场(Hc2)与Nb3Sn类似,但具有更好的应力应变容许特性和高场临界电流密度(Jc)。因此,被认为是下一代高场磁体应用的理想材料。目前国际上报道的Nb3Al超导线材单根长度可以达到2.6 km;在4.2 K和15 T条件下,Jc达到1 000 A/mm2;但是由于制备工艺的复杂性,目前仍然无法实现大规模工业化应用。首先阐述了Nb3Al超导材料的基本特性,如Nb/Al扩散间距小、二者硬度匹配性小和低温热处理导致Al含量偏离化学计量比等,以及由此带来的材料加工和热处理方面的难点;系统介绍了近年来针对Nb3Al超导长线性能提升,在前驱体制备工艺、热处理工艺和表面覆Cu工艺方面的研究进展,并对不同的工艺进行了比较分析,重点讨论了线材制备过程中存在的关键性难点问题;最后,对Nb3Al超导材料的发展趋势进行了展望。
The superconducting transition temperature (Tc) and the upper critical magnetic field (Hc2) of Nb3Al superconductors are similar to those of Nb3Sn, but have better stress-strain tolerance and high field critical current density (Jc). Therefore, it is considered as the ideal material for the next generation of high field magnet applications. Currently, internationally reported Nb3Al superconducting wires can reach a single length of 2.6 km. At 4.2 K and 15 T, the Jc reaches 1000 A / mm2. However, due to the complexity of the preparation process, it is still not possible to achieve large-scale industrial application . Firstly, the basic properties of Nb3Al superconducting materials, such as small Nb / Al diffusion distance, small hardness matching and Al stoichiometry ratio due to low temperature heat treatment, are presented. The difficulties in material processing and heat treatment The research progresses on the performance improvement of Nb3Al superconducting long wire in recent years, the precursor preparation process, the heat treatment process and the surface coating Cu process are introduced systematically. The different processes are compared and analyzed, especially the existence of the wire during the preparation process Of the key issues; Finally, the development trend of Nb3Al superconducting materials are prospected.