Enhanced critical current densities in Cu-sheathed MgB2

Micron-scale mixing of magnesium and boron powders by mechanical alloying allows the MgB2 formation reaction to proceed as low as 450 °C, with high-quality material formed in an hour at 600 °C. At these low reaction temperatures the reaction can be performed in situ in a copper sheath, and it is found that the presence of copper enhances the superconducting properties of the MgB2. Self-field critical current densities, calculated from full critical-state simulation of magnetization hysteresis, are up to 7 × 105 A/cm2 at 13.6 K and 1 × 105 A/cm2 at 30 K.