Nb
3Al multifilamentary wire made by a rapid heating, quenching and transforming (RHQT) process shows not only 3-5 times higher
Jc (4.2K), but also much lower strain sensitivity of superconductivity than that of commercialized (Nb, Ti)
3Sn multifilamentary wire, and is therefore one of the most promising candidates as a next-generation superconductor. However, the Cu stabilization process is an unsolved key technology required to commercialize the RHQT-processed Nb
3Al conductor. Because the RHQT process includes heat treatment at about 2, 000°C, which is much higher than the melting point of pure Cu, we must cover the Nb
3Al wire with a Cu stabilizer after quenching. A stable Nb oxide layer is formed on the surface of the Nb
3Al wire and prevents electrical and thermal conductivities between the Cu stabilizer and Nb
3Al wire. We found that a 1μm thick Cu-ion plating on the Nb
3Al wire removes the Nb oxide layer effectively. The Nb
3Al wire, Cu-plated electrically with several tens of micrometers in thickness after being Cu-ion plated, shows improved
Jc in lower fields and an increase in recovery current, which indicates the improved stability of the Nb
3Al wire.
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