Electron-beam-melted NbTi alloy and its superconductor cable

Abstract

An NbTi alloy with a titanium content of between 44 and 53 wt.% was electron-beam melted, and a multifilamentary superconductor wire was fabricated with an area reduction by 10 7. Critical current densities of 2.68 × 10 7 A cm −2 at 5 T and 1.35 × 10 5 A cm −2 at 7 T were reached with one optimum thermomechanical heat treatment. The results were not critically dependent on the titanium content. Quantitative analysis of the results is presented using the thermodynamic theory of Hampshire and Taylor, and the Larkin-Ovchinnikov collective vortex-pinning theory. The conclusion indicates the possibility of increasing the critical current density of the NbTi alloy using greater area reduction during the manufacture of the cable. This opens new possibilities for the production of a super-clean NbTi alloy using electron-beam melting. This alloy could be produced at a lower cost and with a higher critical current density than the presently available vacuum-arcremelted (VAR) NbTi alloy. An integrated process of vacuum aluminothermic reduction of Nb 2O 5 followed by electron-beam refining and melting of niobium and titanium sheets is presented with a cost analysis.