The critical current properties of 37-filament internal Mg diffusion-processed MgB_2 wires

摘要

Internal Mg diffusion (IMD)-processed MgB_2 wires are known to have a high-density MgB_2 core, which obviously leads to high critical current density (J_c). In this work, we first fabricated 37-filament MgB_2 wires by IMD processing, and we found that J_c for SiC-added 37-filament IMD-processed MgB_2 wires achieved a value of 7.6 × 10~4 A cm~(-2) at 4.2 K and 10 T, which is higher than those of multi-filament wires with a smaller number of filaments (1 filament, 7 filaments) fabricated under the same conditions. We also investigated the critical current properties of both undoped and SiC-added 37-filament IMD-processed MgB_2 wires under different magnetic fields and temperatures. The undoped 37-filament IMD-processed MgB_2 wires achieved J_c value of 1.6 × 10~5 A cm~(-2) at 20 K and 3 T. The engineering critical current density (J_e) achieved 2.8 × 10~3 A cm~(-2) at 20 K and 3 T. The microstructures observed by scanning electron microscopy support the view that the decrease in unreacted B particles by the short diffusion distance is mainly responsible for the high J_c obtained.