Development of Nb3(Al, Ge) Conductors by Diffusion Process for High-Field/High-Current Uses.

Nb3(Al,Ge) conductors prepared from multifilamentary Nb/Al-25at%Ge precursors with a diffusion reaction process at temperatures around 1400°C, have shown critical current density (Jc) in excess of 300 A/mm2 at 21 T and 220 A/mm2 at 23 T at 4.2 K. The diffusion spacing between the Nb and Al-Ge was not required to be reduced down to sub-micron order, which is better to reduce the fabrication difficulties. With large diffusion spacing, the A15 phase formed in equilibrium together with large region of o-phase. The A15 phase was quite Nb-rich. The attainable upper critical field (Hc2) exceeds 28.5 T, which is about 2 T larger than that of the so-called RHQT Nb3Al. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]