Properties Comparison of RHQT Nb 3 (Al 0.95 Ge 0.05 ) Superconductors Formed via Quenched bcc Phase With/Without Disordered A15 Present

This work compared the properties of rapid heating, quenching, and transformation (RHQT) processed Nb3(Al0.95Ge0.05) superconducting wires formed via quenched bcc phase with and without disordered A15 phase present. When using 45 μm Nb as raw material, the quenched wires consisted of a single bcc phase in contrast to both bcc and A15 phase presented in 5-μm Nb wires. After transformation process, all the fabricated Nb3(Al0.95Ge0.05) superconductors are composed of A15 phase, showing higher Tc of 18.2 K than the pure Nb3Al of 17.1 K. The smallest ΔTc value was 0.7 K for the Nb3(Al0.95Ge0.05) superconductor using 45 μm Nb. Both layer Jc and irreversible field (Birr) of 45-μm Nb superconductor are better than that of the 5-μm Nb samples, which can be attributed to higher density of stacking fault formed in the A15 phase transformed from bcc phase. Due to higher Tc of Ge-doped sample, the layer Jc and Birr performances of the best Nb3(Al0.95Ge0.05) superconductor changes from strongly inferior to slightly superior compared to pure binary Nb3Al sample as increasing temperature from 4.2 to 12 K.