CEC-ICMC 2015 - Timetable, Abstracts and Presentations

Shift of the Fp-B curve peak of Nb3Sn conductors with very fine grain sizes

30 Jun 2015, 11:30

15m

Tucson Ballroom AB

Contributed Oral Presentation ICMC-01 - NbTi/Nb3Sn/A15 Processing and Properties M2OrA - Superconductor Materials III: Nb3Sn

Speaker

Xingchen Xu (the Ohio State University)

Description

In an earlier work we demonstrated on a monofilament that the internal oxidation method can significantly refine the grain size and improve the high-field Jc of Nb3Sn strands. In that work we found that as the Nb3Sn grain size was reduced down to 20-50 nm (with an average of 36 nm), the peak of the Fp-B curve shifted from 0.2Birr to 0.34Birr. In this work we further reduce the grain size by using a lower reaction temperature and a higher-Zr Nb-Zr alloy, in order to find out how the Fp-B curve peak shifts as grain size decreases. A pinning theory is also developed to explain the shift of the Fp-B curve peak as grain size is reduced. In this work we also work towards implementing the internal oxidation method in practical multi-filamentary tube type Nb3Sn strands. Schemes to apply this method to rod-restack-process (RRP) and powder-in-tube (PIT) strands are also proposed.