Nb3Al conductors for high-field applications

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.