Fabrication of Ti doped MgB 2/Cu superconducting wires by SHS method in an unsealed furnace

Abstract

Mg 0.9Ti 0.1B 2/Cu wires have been successfully synthesized by the powder-in-tube (PIT) technique combined with the self-propagating high-temperature synthesis (SHS) method in an unsealed furnace. The analysis includes the studies of the sample microstructure, phase composition, critical transition temperature T c and critical current density J c . The experiments show that the PIT technique combined with the SHS method is effective in reducing the Mg volatilization and oxidation. There is little reaction between Mg and Cu in the SHS process, but with the MgCu 2 and CuO phases, the reaction does occur in the inner sheath wall of the copper tube. The findings also indicate that there is little MgO in the sample. The sample has a very strong flux pinning ability at the low magnetic fields since the TiB 2 phase may prevent the growth of MgB 2 grains and lead to a favorable effect on grain refinement. The wires exhibit a high critical current density, e.g. 2.7 × 10 5 A/cm 2 in the 1.0 T field at 4.2 K and 1.3 × 10 5 A/cm 2 in the 2.0 T field at 4.2 K.