Some improvements in laves phase high-field superconductors

Improvements in superconducting properties and workability have been achieved both in V
2
(Hf,Zr) and in V
2
(Hf,Nb), through the effects of additional elements. The V
2
(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 J
c
, 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 V
2
(Hf,Nb) ternary alloys containing hafnium less than 17at% can be fabricated by direct plastic deformation at room temperature. The titanium addition to the V
2
(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 T
c
of 9.9K, upper critical field H
c2
(4.2K) of about 22T and overall J
c
(4.2K) of 1 × 10
⁴
A/cm
²
at 13T are obtained.