Effect of titanium additions to in-situ Nb3Sn wire

Multifilamentary Nb3Sn wires have been prepared by solid state diffusion starting from in-situ cast ingots of Cu plus 30 wt.% Nb. Oxygen contamination was found to have an adverse effect on both the processing and the superconducting performance at high fields of the final wire. In an attempt to divert oxygen from the Nb, a small amount (1 wt.%) of Ti was added to the melt. Processing of the ingot was improved, the final wire consisting of fine, regular ribbonlike filaments. Additions of Al, Hf and Zr were found to have a similar effect. Critical current measurements were made at 4.2 K in inductions up to 15T on wire after tin-plating and reaction. Above 1OT, critical current densities for wires containing Ti were higher than those for wires with no additions. Kramer plots extrapolated to Bc2> 21T. It is seen that the addition of Ti to in-situ Nb3Sn improves both the processing and the high field Superconducting performance.