先反应-后绕型Nb3Al超导线材制备及其电磁特性研究

Comparing to Nb3Sn superconductor, Nb3Al posseses higher upper critical field, higher critical current density and better stress-strain tolerance of the current-carrying capacities, and also could be made into the multifilamentary and round superconducting wires, so it is thought as the optimal choose for the magnet application of the future magnetic confinement nuclear fusion reactor. React and Wind (R&W) is the key that simplifies the fabrication process and thus decreases the pruduction cost of the large-scale superconducting magnets. Although a plenty of studies imply that Nb3Al supercoducting wires could be used to make the R&W superconducting magnets, there are no reports about the structure design, manufacture and superconducting properties of the R&W Nb3Al wires. So in the project, we propose to carry out the studies of the fabrication and the electro-magnetic and mechanical properties of the R&W Nb3Al superonducting wires. By appropriately designing the conductor structures of R&W Nb3Al wires, optimizing the plastic processing of many-components metal-composites and also the heat-treatment conditions of the long wires, key techniques of high-performance R&W Nb3Al superconducting long wire will be developed. By comparing the microstructure and the electro-magnetic and mechanical properties of Nb3Al wires with defferent conductor structures and heat-treatment conditions, the mechanism of the current-degradation and crack-dilatation for R&W Nb3Al wires under the action of the various stress-strain and magnetic fields will be illuminated. And also the conductor structures and physical properties of the obtained Nb3Al superconducting wires will be testified by manufacturing the R&W superconducting magnet coils. Aim of this work is to solve the key basic scientific problems during the fabrication and application of the R&W Nb3Al superconducting wire, and thus bulid the substantial basis for the its future application in magnetic confinement nuclear fusion reactor.

与Nb3Sn相比，Nb3Al具有更高的临界电流密度、临界磁场和应力/应变容许特性，能制作成多芯线材，被认为是聚变堆高场磁体用超导材料的理想选择。先反应-后绕（R&W）是简化大型超导磁体制作工艺、降低磁体制作复杂性的关键。虽然有研究表明，Nb3Al有可能用于制作R&W超导磁体，但是国际上对这种l线材的结构设计、加工及性能还缺乏系统研究。本项目提出开展R&W型Nb3Al长线设计、制备及电磁特性研究，通过合理设计R&W型Nb3Al线材导体结构，优化多元金属复合体导线塑性加工及长线热处理工艺，获得R&W型Nb3Al超导长线制备关键技术以及其电磁特性，阐明该在应力/应变、磁场作用下超导性能的退化及裂纹扩展损伤机理；并且制作R&W超导磁体对研制的线材结构和性能进行验证，从而解决R&W型Nb3Al长线制备及应用过程中的关键基础科学问题，为将来的磁约束聚变堆大型超导磁体应用奠定基础。

与Nb3Sn相比，Nb3Al具有更高的临界电流密度、临界磁场和应力/应变容许特性，能制作成多芯线材，被认为是聚变堆高场磁体用超导材料的理想选择。本项目主要开展R&W型Nb3Al长线设计、制备及电磁特性研究，通过合理设计R&W型Nb3Al线材导体结构，优化多元金属复合体导线塑性加工及长线热处理工艺，获得R&W型Nb3Al超导长线制备关键技术以及其电磁特性，阐明该在应力/应变、磁场作用下超导性能的退化及裂纹扩展损伤机理；并且制作R&W超导磁体对研制的线材结构和性能进行验证，从而解决R&W型Nb3Al长线制备及应用过程中的关键基础科学问题，为将来的磁约束聚变堆大型超导磁体应用奠定基础。主要研究成果如下：（1）研制出国内第代Nb3Al长线卷对卷高温热处理设备及长线稳定热处理工艺技术；（2）成功制备出国内第一根百米量级高性能30芯Nb3Al超导线材，该线材直径0.86 mm，长度120 米，在4.2 K、12T下Ic性能达到376 A；并被用于中科院等离子所CICC导体研制；（3）在国际上首次提出并发展了基于非静液挤压路线的Nb3Al前驱体导线制备工艺技术，并首次在36芯Nb3Al前驱体导线结构上，成功引入了Ta阻隔层，有效地抑制了Nb3Al超导线材励磁过程中的“磁通跳跃”技术难题。

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