Fabrication and Microstructure of 30-Filament Jelly-Roll Nb3Al Superconducting Wires with Very High Critical Current Density.

In this paper, we report successful fabrication of a 30-filament 150 m-length Nb3Al superconducting wire with very high critical current density (Jc) based on our second-generation reel-to-reel rapid heating and quenching (RHQ) heat-treatment equipment. The manufacturing process of 30-filament Nb3Al precursor wire and the effect of RHQ heat-treatment on the microstructure and Jc of Nb3Al superconducting wires are discussed. We have fabricated two wires with varying diameter such as 1.3 mm and 0.72 mm. For the Dia. of 1.30-mm Nb3Al wire, the critical current, Ic at 4.2 K and 12 T reaches 1078 A with optimized RHQ heat-treatment conditions. For the wire of finer Dia. 0.72 mm, it has the layer and non-Cu Jc of up to 3770 and 924 A/mm2 at 4.2 K and 12 T, respectively. Considering the excellent strain–stress tolerance of Nb3Al, along with competitive superconducting properties, Nb3Al superconductor is an attractive candidate for the large-scale superconducting magnet applications. [ABSTRACT FROM AUTHOR]