Nano-sized amorphous/semi-crystalline boron ratio and external Mg effects on transport and structural properties in MgB2 IMD wires

Transport and structural properties of MgB2/Fe wires produced by redesigning internal Mg diffusion process

“…The internal magnesium diffusion method, which enables a significantly higher in-field critical current density (J c ) than the PIT method, is more advantageous in terms of using MgB 2 instead of NbTi in the MRI magnet [8][9][10][11]. However, the J e in internal Mg diffusion (IMD) wires is lower than that of PIT wires because a large hole is formed in the center of IMD wire due to diffusion of the central Mg rod into the surrounding boron during heat treatment [11][12][13][14][15][16]. The core uniformity is also challenging in the production of long IMD wires due to the variations in the packing density of boron powder along the IMD wire, leading to changes in the superconducting properties after heat treatment.…”