Nb
3Al with stoichiometric composition shows
Tc above 19K and
Hc2 (4.2K) above 30T, much higher than in commercially available Nb-Ti wire and Nb
3Sn wire. Therefore the developments of fabrication processes for Nb
3Al conductors were performed early on with zeal, but ended without success because stoichiometric Nb
3Al is unstable at any temperatures except about 2, 000°C. Moreover, the fabrication speed of Nb
3Al through solid-state diffusion reaction is very slow. To overcome these difficulties, a recent new process, RHQT (rapid-heat, quench, and transformation), was developed for fabricating Nb
3Al multifilamentary conductors with near-stoichiometric composition and fine-grained crystals. Through this process we have succeeded in the fabrication of Nb
3Al multifilamentary wires showing 2 to 5 times larger
Jc at 4.2K than those of commercialized superconductors in any field, and their
Tc of about 17.6K and
Hc2 (4.2K) of about 26T are similar to those of the (Nb, Ti)
3Sn wire. Furthermore, excellent tolerance to mechanical strain is also obtained for the Nb
3Al conductor. I believe the new Nb
3Al conductor should soon be commercialized and take the place of Nb
3Sn conductor. In this paper I would like to describe the historical progress in the Nb
3Al conductor fabrication process up to the birth of the RHQT process.
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