高场磁体用RRP Nb3Sn股线的研制

采用Rod Restack Process(RRP)研制了单根线长大于1500m的高场磁体用Nb3Sn股线,股线选用Nb作为扩散阻隔层,分布于各亚组元周围。在热处理时Nb阻隔层不但可以阻止Sn向稳定体Cu区的扩散,防止稳定体的Sn扩散污染,确保股线具有较高的剩余电阻率(RRR),同时,靠近Sn源内侧的Nb参与固态扩散反应生成A15相Nb3Sn,贡献临界电流。在股线的制备过程中,采用Nb-47%Ti(质量分数)芯代替部分Nb芯的方式添加元素Ti,达到了Ti元素添加目的,该方法因为使用了已经商业化的Nb-47%Ti而有效控制了制作成本。对该股线进行热处理以及超导性能测试研究表明:640℃,60h热处理条件下,股线在12T,4.2K,0.1μV/cm下的Ic为514A,股线的RRR为148,具有良好的绝热稳定性;在650℃,100h下股线的Ic为599A,RRR=3.77。股线扩散阻隔层以及添Ti方式的成功选择,为获得长线打下了基础,为股线性能的初步研究及后续的实验提供了直接参考。

Fabrication and Investigation of Nb3Sn Strands by RRP for High Field Magnet

The Nb 3 Sn strands over 1500 m piece length by Rod Restack Process(RRP) for high field magnet were fabricated by Western Superconducting Technologies Co.,Ltd.(WST).The distributing Nb barriers were employed around each sub-element in the process,which not only protect the Cu stabilization from the pollution of Sn,but also contribute to the critical current for forming A15 phase Nb 3 Sn during the reaction.Meanwhile,Nb-47wt%Ti filaments were adopted to replace some of Nb as the resource of Ti adding in the process,lowering the production price the commercial Nb-47wt%Ti.The testing results show that the I c of the strands with better stability is 514 A at 12 T,4.2 K,0.1 μV/cm with the heat treatment of 640 ℃,60 h and the RRR value is 148.While the I c is 599 A with the heat treatment of 665 ℃,60 h and RRR value is 3.77.The success choosing of barrier and Ti doping make it possible to develop higher quality strands,including long piece length and high critical current.