Fabrication and transport critical currents of multifilamentary MgB2/Fe wires and tapes

Multifilamentary MgB2/Fe wires and tapes with high transport critical current densities have been fabricated using a straightforward powder-in-tube process. After annealing, we measured transport jc values up to 1.1 × 105 A cm−2 at 4.2 K and in a field of 2 T in a MgB2/Fe square wire with seven filaments fabricated by two-axial rolling, and up to 5 × 104 A cm−2 at 4.2 K in 1 T in a MgB2/Fe tape with seven filaments. For higher currents these multifilamentary wires and tapes quenched due to the insufficient thermal stability of the filaments. Both the processing routes and deformation methods were found to be important factors for fabricating multifilamentary MgB2 wires and tapes with high transport jc values.