Performance of Nb 3 Al superconducting wires with kilometer-grade length after treatment via reel-to-reel joule heating

Abstract

In view of practical manufacturing of Nb₃Al materials, it is a triumph that we have fabricated kilometer-grade single-filament jelly-roll Nb₃Al precursor wires on this occasion and then investigated the effects of large heating current on superconducting properties of the sample wires treated by rapid heating, quenching and transformation (RHQT). The optimized RHQ current explored in this experiment is 270 A, in which samples show some distinct properties, an abrupt superconducting transition, an excellent onset superconducting transition temperature (T_c) of 18.2 K and a relatively high critical current density (J_c) of 6.68 × 10⁴ A/cm² at 10 K and 7 T. Since the current variation keeping wires ductile after quenching comes clear, continuous kilometer-class wiring under large current heating will be real as long as the proportion of Nb and Al in precursor is improved or by other means Nb/Al composite in RHQT Nb₃Al is enhanced. This work has really pushed the commercial application of Nb₃Al materials.