A wide variety of powders, including Nb, Ti, Zr, Hf and W, metal oxides such as Nb2O5, Ti2O5, V2O5 and other compounds such as SiC, SrCO3 and boron nitride, were used - at the 10wt% level - as additions to commercial MgB2 powder for the fabrication of single-core ex situ wires using groove and 2-axis rolling deformation and final heat treatment (950C, 0.5h) in Ar. Transport current measurements showed that metal particle addition led to an especially significant improvement in current carrying capacity. The presence of normal particles influenced both the resistivity and also the thermal conductivity of the MgB2 core, and the improved internal stability could be responsible for increased critical current values.

Improvement of the Current Carrying Capability of ex situ MgB2 Wires by Normal Particle Additions. P.Kovác, I.Husek, T.Melisek, C.R.M.Grovenor, S.Haigh, H.Jones: Superconductor Science and Technology, 2004, 17, 1225-30