ICEC/ICMC 2014 Conference

Effect of heat-treatments on the Jc of NbTi superconductor for high magnetic fields

Not scheduled

1h 45m

Poster presentation (105min)

Speaker

Mr Yonghua Li (Western Superconducting technologies co.,ltd.)

Description

The critical current density of NbTi superconductors is affected by a complex schedule of heat-treatments and strain. The optimization of temperature, time and final strain are good for obtaining appropriate quantity and size of the α-Ti precipitates. In this paper, a superconductor with 3366 filaments and 1.6 Cu/Sc ratio was designed and high homogeneity Nb47Ti alloy was applied for the fabrication of the NbTi superconductors. Different heat-treatment schedules varied in temperature, time and strain were carried out on NbTi strand samples. The critical current of these samples were tested at 4.2 K under different magnetic fields ranging between 7 to 9 Tesla. The following results are obtained: the appropriate temperature for gaining fine Jc in high magnetic fields is ranging between 400℃ to 480℃ and the Jc will decrease with temperature above 480℃; the optimal final strain for the NbTi samples was about 5.0; it was a better way to get optimal critical current density that pre-aged with low temperature and short time and combined with high temperature and short time ageing. The optimal critical current density could reach 726 A/mm2 at 9 T and 4.2 k. Key words: heat-treatment, critical current density, NbTi superconductor.