Transport properties of sealed MgB2/Fe/Ni multifilamentary wires heat treated in air

Ni sheathed multifilamentary MgB2 wires with Fe barrier and Cu stabilizer were prepared by the in situ Powder-In-Tube (PIT) method. After rolling, the ends of the wires were sealed by a simple capping technique and the wires were directly heat treated in air, without vacuum or any inert atmosphere. The quality of the wires was assessed by analysing the phase assemblage and measurement of superconducting properties such as R–T, JC–T and JC–H. Phase analysis revealed that only traces of MgO was formed in the superconductor core. Typical multifilamentary wires prepared by this method showed a TC ≈ 38.5 K and ΔTC ≈ 1 K and JC of the order of 105 A/cm2 at 6 K (0 T) and 104 A/cm2 at 4.2 K (6 T) respectively. These values are quite comparable with the values obtained for wires heat treated in inert atmosphere.

► In this work, the feasibility of making MgB2 based multifilamentary wires by direct heat treatment in air using a novel capping technique has been demonstrated. ► Superconducting properties of the MgB2 wires (self-field and in-field) prepared using this method are found to be as good as or better than the samples prepared in vacuum. ► The avoidance of vacuum or inert atmosphere for production of MgB2 superconductors will make the process simple, economical and attractive.