MgB2 Multicore Wire Prepared by IMD Technology—Investigation of the MgB2 Layer Formation During Annealing

Seven-core MgB2wires were prepared by the IMD-technology with Monel/Glidcop/Nb resp. /Ti-sheath. As special feature the first deformation steps of the monocore wire were carried out by hydrostatic extrusion. The further deformation was taken by swaging, wire drawing resp. groove rolling. The characterization of the mono- and the multicore wire was made by metallographic cross sections, SEM, resistance, and critical current measurements in dependence on temperature and magnetic field. In order to investigate the diffusion and reaction process in more detail, several samples were annealed under different conditions (peak temperature, dwell time). The best properties, i.e., homogeneous microstructure of the filaments and highest critical current density, were observed at samples annealed at peak temperatures lower than 650 °C, the melting temperature of Mg.