Fabrication of Nb3Al superconducting wires by utilizing the mechanically alloyed Nb(Al)ss supersaturated solid-solution with low-temperature annealing

• This paper reported superconducting properties of the powder-in-tube Nb3Al wires.
• The Nb3Al wires were made by using Nb(Al)ss supersaturated solid solution powders.
• The Cu-matrix Nb3Al superconducting wires have been successfully fabricated.
• The transport Jc of Nb3Al wires at 4.2 K, 10 T is up to 12,700 A/cm2.

High-performance Nb3Al superconducting wire is a promising candidate to the application of high-field magnets. However, due to the production problem of km-grade wires that are free from low magnetic field instability, the Nb3Al wires made by rapid heating, quenching and transformation (RHQT) are still not available to the large-scale engineering application. In this paper, we reported the properties of the in situ powder-in-tube (PIT) Nb3Al superconducting wires, which were made by using the mechanically alloyed Nb(Al)ss supersaturated solid solution, as well as the low temperature heat-treatment at 800 °C for 10 h. The results show that Nb3Al superconductors in this method possess very fine grains and well superconducting properties, though a little of Nb2Al and Nb impurities still keep being existence at present work. At the Nb3Al with a nominal 26 at.% Al content, the onset Tc reaches 15.8 K. Furthermore, a series of Nb3Al wires and tapes with various sizes have been fabricated; for the 1.0 mm-diameter wire, the Jc at 4.2 K, 10 T and 14 T have achieved 12,700 and 6900 A/cm2, respectively. This work suggests it is possible to develop high-performance Cu-matrix Nb3Al superconducting wires by directly using the Nb(Al)ss supersaturated solid-solution without the complex RHQT heat-treatment process.