Some improvements in laves phase high-field superconductors

Improvements in superconducting properties and workability have been achieved both in V2(Hf,Zr) and in V2(Hf,Nb), through the effects of additional elements. The V2(Hf,Zr) can be fabricated into a conductor form by a composite diffusion process in which a composite of vanadium sheath and Zr-Hf alloy core is cold-worked and then heat treated. The addition of hafnium to the vanadium sheath considerably improves the critical current density Jc, and moreover it makes the fabrication of the composite easier by reducing the difference in workability between the sheath and the core. The multifilamentary V-(1-2)at%Hf/Zr-25at%Hf wire may be practically useful for generating magnetic fields up to 15T. The V2(Hf,Nb) ternary alloys containing hafnium less than 17at% can be fabricated by direct plastic deformation at room temperature. The titanium addition to the V2(Hf,Nb) significantly improves both the superconducting properties and the workability. In the cold-rolled V-19at%Hf-6at%Ti-8.3at%Nb, transition temperature Tcof 9.9K, upper critical field Hc2(4.2K) of about 22T and overall Jc(4.2K) of 1 × 10⁴A/cm²at 13T are obtained.