Improvement of the current carrying capability of exsitu MgB2 wires by normal particle additions

Abstract

A wide variety of powders, including Nb, Ti, Zr, Hf and W, metal oxides likeNb2O5,Ti2O5,V2O5 and othercompounds like SiC, SrCO3 and boron nitride, have all been used at the 10 wt% level as additions into commercialMgB2 powder for the fabrication of single-core, ex situ wires using grooveand two-axial rolling deformation and final heat treatment at950 °C /0.5 h in Ar. Transport current measurements have shown that metal particle addition leads toan especially significant improvement in current carrying capacity. The presence of normalparticles influences both the resistivity and also the thermal conductivity of theMgB2 core, and the improved internal stability may be responsible for the increased criticalcurrent values. This observation may be very important for future development of practicalMgB2 composite superconducting wires.