抄録
Nb3Al multifilamentary conductors have been fabricated via a newly developed process where the “precursor” of supersaturated bcc-solid-solution Nb(Al)ss/Nb is first formed by quenching the Jelly-roll (or rod-in-tube) Nb/Al composites from the high-temperature region and subsequently transformed to Nb3Al of nearly stoichiometric composition with fine grains. Although the precursor contains many spherical defects (probably the Kirkendall void), it is flexible and ductile even at room temperatures, enough to be Cu stabilized, cabled, flat-roll formed, and wound to a coil before being aged and transformed. The transformed Nb3Al shows high-field critical current densities much larger than those for conventionally prepared Nb3Al conductors, where the Nb3Al phase is known to be off-stoichiometric. The degradation of critical current densities with -0.7% intrinsic strain is about 20% at 12T, comparable with those for conventional JR-Nb3Al conductors of high strain tolerance. An attempt is made to further improve the high field performance by adding Ge to Al.
