A new structural design to improve Mg diffusion in IMD MgB₂ wires

In this study, a new method called three-hole internal magnesium diffusion (TH-IMD) was applied to the fabrication of superconducting monofilament MgB2/Fe wires. In the TH-IMD method, three thin magnesium rods were placed within the boron powder in a triangular arrangement instead of a single magnesium rod in the middle of the wire, as in the standard IMD method. The aim of the TH-IMD method is to ensure the complete diffusion of magnesium into the surrounding boron during the heat treatment of IMD wires and to obtain uniform MgB2 structure throughout the core region. To determine optimal heat treatment conditions and wire diameters, transport measurements (R-T and I-V) were conducted under magnetic fields up to 11 T. Microstructural analysis was performed using optical microscopy, while phase composition was determined via XRD.