Improvement in coordination deformation and interface of high-performance IMD–MgB2 superconducting wire via hot drawing process

IMD-MgB 2 superconducting wires suffers from “sausage knots”, core breakage, and surface defects during traditional cold process, due to poor plasticity of central Mg rod and difficulties in coordinating deformation between filling boron powder and metal components. It severely impairs the wire's current-carrying performance. To solve this problem, in this study, a novel hot drawing process for IMD-MgB 2 superconducting wires based on thermomechanical coupling effect was first proposed. The effect mechanism of loading methods and deformation temperature on coordinated deformation between powder and metals, microstructure evolution of superconducting phase and superconducting properties of IMD-MgB 2 wire were studied. The improvement in inter-component interface quality and superconducting phase grain control within IMD-MgB 2 superconducting wire based on thermo-coupling effect were revealed. The relationship among hot working parameters, precursor structure and superconducting performance were systematically elucidated. The results indicated that, the "sausage knots" and central Mg rod’ breakage were completely eliminate by using hot drawing. The wire drawn at 300°C exhibited the best coordinated deformation, with a straight interface and uniform layers. The sintered MgB 2 superconducting phase had fine and uniform grains, as well as high density, and it achieved a high critical current density J c of 1.21 × 10 6 A/cm 2 under conditions of 4.2 K and 2 T.