Mechanical and superconducting properties of 6-filament MgB2 wires reinforced by Cu, Cu–Nb and NbTi

Abstract

The comparisons of strengthening abilities of Cu, Cu–Nb, and NbTi for 6-filamentary MgB1.92(TiC)0.08/Nb/Cu wires and the electrical properties of the best reinforced wire are investigated. The Cu–Nb reinforcing core is more appropriate for manufacturing MgB2 wires. It is observed that the Cu–Nb reinforced wire sintered at 750°C for 2h has the highest yield strength of 101.8MPa. With the sintering temperature increasing, the yield strength of the Cu–Nb and NbTi reinforced wires increased while the value slightly decreased in the case of Cu reinforced one in this study. According to our calculations, those mechanical properties are suitable for the application requirements of superconducting magnets in low field with the critical engineering current Ic of 197 and 205A (Jce exceeding 1.7×104 and 1.8×104A/cm2) before and after 70MPa axial load on the wire at 20K, 1.5T respectively. And within the working temperature range from 10K to 35K, the Cu–Nb reinforced wires show the lowest resistivity as well. The Cu–Nb reinforced long MgB1.92(TiC)0.08/Nb/Cu wires with unit length over 1km have already been manufactured using the similar process. The Cu, Cu–Nb, and NbTi reinforced 6-filament MgB1.92(TiC)0.08/Nb/Cu wires are fabricated by in situ PIT (Powder-in-Tube) method respectively.