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, J(C)-T and J(C)-H. Phase analysis revealed that only traces of MgO was formed in the superconductor core. Typical multifilamentary wires prepared by this method showed a T-C approximate to 38.5 K and Delta T-C approximate to 1 K and J(C) of the order of 10(5) A/cm(2) at 6 K (0 T) and 10(4) A/cm(2) at 4.2 K (6 T) respectively. These values are quite comparable with the values obtained for wires heat treated in inert atmosphere. (C) 2011 Elsevier B.V. All rights reserved.