High transport critical current in MgB2/Fe wire by in situ powder-in-tube process

MgB2/Fe wires and MgB2/Ta/Cu wires were prepared through the in situ powder-in-tube method by using Mg and B powders at ambient pressure. The phase compositions, microstructural features are investigated by X-ray diffraction and scanning electron microscope. The transport critical current properties are measured by the standard four-probe technique. It is found that no impurity phase is formed in MgB2/Fe wire. At the same time, there are almost no reaction between iron and magnesium according to the results of X-ray diffraction analyses. In addition, it is found that MgB2 grains in Fe clad are fined by comparing the micrograph of Fe-clad wire and Ta-clad wire. The high transport critical current density (J(c)) of 6.0 x 10(4) A/cm(2) (5 K, 4 T) and 5.2 x 10(3) A/cm(2) (15 K, 6 T) are obtained in the MgB2/Fe wire. (C) 2003 Elsevier B.V. All rights reserved.