Superconducting Properties of High-Energy Ball-Milled Magnesium Diboride Composites

Al-sheathed MgB₂ superconducting wires were fabricated, using pre-reacted and high-energy ball-milled MgB₂ as starting powders. Although the heat treatment of the wires was carried out at a low temperature (500degC) resulting in an insufficient grain connectivity of MgB₂, high-energy ball-milling was beneficial both for the densification and increasing Jc values. The addition of C to MgB₂ increased the critical current density. The addition of Pb content as high as 50 wt.% did not lower the critical temperature (Tc) of MgB₂, while apparently enhancing densification.