通过Nb，Ti扩散反应制备不同成分的超导体

NbTi Superconductors with Variable Compositions Produced by Diffusion Reaction of Niobium and Titanium Sheets

摘要:

利用Nb片和Ti片交替组配加工,经扩散反应制备了Ti含量在42.56%-56.62%之间的3种不同成分的NbTi超导线。运用扫描电镜(SEM)观察了Nb/Ti界面的扩散形态及微结构,并对热处理工艺和不同Ti含量对临界电流密度(Jc)的影响进行了讨论。结果表明:随着Ti含量增加,可提高超导线在低场(<5T)时的临界电流密度Jc。该工艺制备的NbTi超导线材的Jc可达到2800A/mm2(5T,4.2K)和4200A/mm2(3T,4.2K)。随着Ti含量的增加,试样的Jc在低场时很高,而在高场时的性能偏低,且下降迅速,而Ti含量低的试样的Jc衰减相对缓慢些。对Ti含量较高的合金,在一定温度下,选用较短的热处理时间,可获得高的Jc,对Ti含最较低的合金,则要求较长热处理时间。

Abstract:

Three different compositions of NbTi wires have been fabricated by using alternately pure Nb and Ti sheets with Ti contents from 42.5% to 56.6% by adjusting the relative thickness of the Nb and Ti sheets in the monofilaments. Two kinds of heating treatments were discussed and the Nb/Ti interface microstructure and diffusion morphology of cross-section have been investigated by scanning electron microscopy (SEM). The results show that the Jc values are 2 800 A/mm2 at 5 T/4.2K and 4 200 A/mm2 at 3 T/4.2 K. With the increase of Ti content, Jc is higher at low magnetic fields (<5 T), but lower and decreasing rapidly at high magnetic fields. Jc decreases slight slowly for the lower Ti samples. At a given temperature, higher Jc can be gotten by using shorter time of heat treatment for the higher Ti samples, and by using longer time for the lower Ti samples.