Thierry Verhaege

Effects of Heat-Treatments and of Processing Parameters on the Microstructure of Multifilamentary Nb-46.5 wt% Ti Superconductors

The superconducting behaviour of the conventional Nb-Ti wires is governed by their internal microstructure 1,2,3,4,5,6 whereas that of the ultra-fine filaments seems to arise from surface pinning at the boundaries between the filaments and the matrix 7. Therefore, it is particularly pertinent to examine the effects of the manufacturing process both on the internal and on the interfacial structure of the filaments. The authors have recently demonstrated that the Alsthom manufactured wires are highly polyphased 6,8 which can contain among other phases, significant amounts of interfacial intermetallic compounds and of internal α″ martensite.