Superconducting properties of MgB 2 wires and tapes with different metal sheaths

Abstract

We have successfully fabricated mono- and multifilamentary MgB 2 wires and tapes with different sheathed metals such as Cu, Ta, NbZr and Fe by the powder-in-tube method. The phase compositions, microstructure features and superconducting properties are investigated by X-ray diffractometer, optical microscopy, SEM, standard four-probe technique and SQUID magnetometer. The results indicate that there is no reaction between the sheathed metals used here except Cu. For the Cu/Ta/MgB 2 wire, the irreversibility field achieves 6.6 T at 5 K and J c is higher than 10 5 A/cm 2 at 5 K in self-field. By using NbZr as a buffer layer, 18-filamentary Cu/MgB 2 tapes show a transport high J c of 8×10 4 A/cm 2 (10 K self-field). Remarkably, we prepared the Fe/MgB 2 wire with high transport J c of 5.6×10 4 A/cm 2 (15 K, 3 T) and 5.1×10 4 A/cm 2 (25 K, 2 T). The reasons for the improvement of J c in high fields were briefly discussed.