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

Abstract In this study, a new method called three-hole internal magnesium diffusion (TH-IMD) was applied to the fabrication of superconducting monofilament MgB 2 /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 MgB 2 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.