金属系超電導線材 [6

Abstract

In this article, the fabrication process, microstructure and superconducting performance of B1(NaCl), C15(Laves) and Chevrel crystal-type compounds are surveyed. B1-type compounds, such as NbN, show a Bc2 (4.2 K) exceeding 30 T and a high Jc in a film configuration. NbN and NbCN tapes were fabricated using high-rate sputtering and CVD processes. The performance of NbN films is fairly structure sensitive. C15-type compounds, such as V2(Hf, Zr) are attractive due to the combination of high Bc2 (4.2 K) of ~24 T and better mechanical properties than other compound superconductors. Multifilamentary V2(Hf, Zr) wires were fabricated from a composite of V matrix and Hf-Zr cores. The superconducting properties of B1 and C15-type compounds are much less sensitive to mechanical strain and neutron irradiation than other compounds. Chevrel-type compounds, such as PbMo6S8, have attracted interest due to their extremely high Bc2 (4.2 K) of ~50 T. The Chevrel-type compound wires were fabricated using a powder-in-tube process, and their Jc is effectively improved by hot isostatic pressing. A substantial stress on superconducting wires arises from the magnet winding, the thermal contraction as a result of cooling to operation temperature, and the magnetic Lorentz force during operation. The superconducting performance of compound wires is quite sensitive to mechanical strain. Then finally, strain effects in different compound wires are briefly described.