High-quality monofilamentary MgB2 wires with Fe sheaths were fabricated by using the powder-in-tube method at ambient pressures. The phase compositions, microstructure features and flux-pinning properties were investigated by using X-ray diffractometry, SEM, transmission electron microscopy and a standard 4-probe technique. It was found that MgB2 did not react with Fe. The results indicated that the MgB2 wires were dense and only MgB2 and a few MgO phases existed in the core area. The MgB2/Fe wires exhibited very high transport critical current densities of 1.43 x 105A/cm2 (4.2K, 4T), 2.8 x 104A/cm2 (4.2K, 6T), 3.72 x 104A/cm2 (15K, 4T) and 2.34 x 104A/cm2 (25K, 3T). The maximum flux pinning force exhibited a peak at 4T at 4.2K; suggesting strong pinning at high fields.

High Critical Current Density in MgB2/Fe Wires. Y.Feng, G.Yan, Y.Zhao, X.J.Wu, A.K.Pradhan, X.Zhang, C.F.Liu, X.H.Liu, L.Zhou: Superconductor Science and Technology, 2003, 16, 682-4