Improved current density of filamentary MgB2 wire by two-stage formation

Abstract

Filamentary MgB2/Ti/Cu/SS wire is subjected to a stage formation process combining two heat treatments and a mechanical deformation by two-axial rolling in between. It is found that a low temperature starting heat treatment at 600°C/24min followed by the rolling deformation and a final annealing at 850°C/30min is able to increase Jc (4.2K, 8T) by 27%. This improvement is explained by a favorable combination of ex situ/in situ mixture and filament densification through the intermediate rolling. Therefore, the two-stage formation process can be useful for increasing current carrying capacity in practical MgB2 wires.