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 MgB ₂ 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 × 10⁴ A/cm² (5 K, 4 T) and 5.2 × 10³ A/cm² (15 K, 6 T) are obtained in the MgB ₂/Fe wire.