通过Nb，Ti扩散反应制备不同成分的超导体

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。

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

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.