We investigated the applicability of Cu as sheath materials for MgB 2 wires prepared by in situ PIT (powder-in-tube) method in comparison with stainless steal. Since the critical current density of MgB2 increases with TiH2 doping, we prepared TiH2 doped MgB2 Cu sheath wires 40 m in length and ∅ 1.0 mm or 0.5×1.0 mm2 in cross section by rotary swaging, drawing, and two-axial rolling under cold working. We then annealed the samples at 600-850 °C for 1-2 h in Ar gas atmosphere. The critical current of TiH2 (6%) doped MgB2/Cu short sample annealed at 650 °C reached 208 A (Jc=230 kA/cm2) at 4.2 K and self-field. We also fabricated several coils using these wires. The Ic value was ∼100 A at 4.2 K for a coil prepared with use of a 5 m length wire. These results suggest that it is possible to fabricate Cu sheathed MgB2 wires with good performance by using the in situ PIT method.
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