Nb₃Al conductors for high-field applications

Abstract

Nb3Al has been considered as an alternative to Nb3Sn for high-field and large-scale applications, since an extremely high critical current density and excellent strain tolerance were demonstrated in Nb3Al by laboratory tests. Thus, there have been a great number of efforts in the exploration of new fabrication processes for Nb3Al. The processes explored can be classified into three groups: low-temperature processes (jelly-roll, powder metallurgy, clad chip extrusion, rod-in-tube), high-temperature processes (laser- or electron-beam irradiation), and transformation processes. This review describes Nb3Al conductors for each processing group, focusing on current topics relating to the rapid-heating, quenching and transformation method in which an excellent Nb3Al conductor can be obtained with a multifilamentary structure over several hundred metres in length.

Critical Current and Fracture Behavior of Nb3Al Superconducting Strands under Cyclic Electromagnetic Force

“…In these applications, the superconducting wire requires high critical current properties and high tolerance to mechanical stress and strain [1]. In particular, the large-scale magnets have generally been fabricated by the react & wind process; coil winding is carried out after reaction of the brittle superconducting phase.…”

“…In particular, the large-scale magnets have generally been fabricated by the react & wind process; coil winding is carried out after reaction of the brittle superconducting phase. Nb 3 Al strands have excellent strain tolerance and critical current properties in a practical metal superconductor [1]. So far, the effects of mechanical strain on their superconducting properties have been investigated for nuclear fusion magnets [2][3][4][5][6].…”

A New Wire Fabrication Processing Using High Ga Content Cu-Ga Compound in V3Ga Compound Superconducting Wire

“…V based superconducting material has a much shorter decay time of induced radioactivity compared with the Nb based materials. We thought that the V 3 Ga compound was one of the most promising materials for the``low activation and higher field superconductors'' for an advanced fusion reactor. However, the present critical current density ( J c ) property of V 3 Ga compound wire is insufficient for apply to fusion magnet applications.…”

“…We thought that the V 3 Ga compound was one of the most promising materials for the``low activation and higher field superconductors'' for an advanced fusion reactor. However, the present critical current density ( J c ) property of V 3 Ga compound wire is insufficient for apply to fusion magnet applications. We investigated a new route PIT process using a high Ga content Cu Ga compound in order to improve the superconducting property of the V 3 Ga compound wire.…”

“…Fig. 6 The typical SEM photographs of V 3 Ga grains at the V sheath and powder core sides when were heat treated at 700 and 800°C for 50 h. Fig. 7 The relationship between midpoint T c and heat treatment temperature on the high Ga content PIT precursor wires.…”