Fabrication and Electromagnetic Properties of 24-Filament Jelly-Roll Nb3Al Superconducting Long Wire with Reel-to-Reel Rapid Heating and Quenching Heat Treatment

In this paper, a simple 24-filament structure Nb3Al superconducting wire has been firstly prepared by using the jelly-roll Nb/Al composite wire, the reel-to-reel rapid heating and quenching (RHQ), and phase transformation heat treatment. In order to obtain the Nb3Al long wire with good superconducting properties, various heating current (HC) and wire moving speed (WMS) were used to produce high-quality Nb(Al)ss supersaturated solid solution during RHQ process; thereafter, the Nb(Al)ss wire was put into the Cu tube and drawn for preparing the Cu-cladded Nb3Al wire. The results suggest that for the Nb3Al wire with the HC 262 A and WMS of 300 mm/s, its onset Tc and layer Jc at 4.2 K and 12 T measured by the transport way reach 17.7 K and 1.58 × 105 A/cm2, respectively. The magnetization measurement (M-H) of Nb3Al wires indicate that the diameter reduction of Nb(Al)ss solid solution wires after RHQ will significantly improve their grain connectivity and thus Jc properties at the optimal heat treatment conditions. The work suggests the simple-structured Nb3Al superconducting wire is promising to the practical high-field magnet application.