Fabrication of MgB2/Cu Wires Utilizing the In-situ PIT Method

We investigated the applicability of a Cu sheath to MgB2 wires that were prepared utilizing the in-situ synthesis PIT (powder-in-tube) method and compared it with that of stainless steel. Since the critical current density of MgB2 increases with TiH2 doping, we prepared TiH2-doped Cu sheath MgB2 wires 40 m in length and φ1.0 mm or 0.5x1.0 mm2 in cross-sectional dimension utilizing rotary swaging, drawing, and two-axial rolling at room temperature. We then annealed the samples at 600∼850°C for 1∼5hr in an Ar gas atmosphere. The critical current of the TiH2 (6%)-doped MgB2/Cu short sample annealed at 650°C reached 139A(JC = 132kA/cm2) at 4.2 K and ambient field. We also investigated the effect of repeated rolling and annealing on the critical current density of MgB2/SUS wires and confirmed that the enhancement of JC is caused by the densification of MgB2 cores. Finally, we concluded that Cu-sheathed MgB2 wires produced utilizing the in-situ PIT method are promising for practical use.