Fabrication and superconducting properties of a simple-structured jelly-roll Nb₃Al wire with low-temperature heat-treatment

Highlights: • Nb₃Al superconducting wires with Cu-matrix and different filament numbers were prepared by the jelly-roll method. • The length of 18-cores Nb₃Al superconducting wire reaches 100 m without any breakage and intermediate anneal. • This wire has the uniform filament-shapes and fine long-wire homogeneity. • This Nb₃Al long wire has the T_c of 13.4 K and J_c of 4.7 × 10⁴ A/cm² at 4.2 K and 12 T. - Abstract: With extremely high critical current density (J_c) and excellent strain tolerance, Nb₃Al superconductor is considered as an alternative to Nb₃Sn for application of high-field magnets. However, owing to their complex structure, Nb₃Al superconducting wires can hardly meet the requirement of engineering application at present. In this work, a novel simple-structured Nb₃Al superconducting wires with Cu-matrix and different filament numbers were prepared by the conventional jelly-roll method, as well as a heat-treatment of 800–850 °C for 20–50 h. The results show that a 18-filament superconducting wire with length longer than 100 m can be successfully prepared by this method, and also this Nb₃Al long wire has the T_c of 13.4 K and J_c of 4.7 × 10⁴ A/cm² at 4.2 K and 12 T. These suggest that with further optimization, the simple-structured Nb₃Al superconducting wires are very promising to fabricate the km-grade long wires to meet the requirement of engineering application