Niobium-aluminum precursor wire, niobium-aluminum precursor twisted wire, niobium-aluminum superconducting wire, and niobium-aluminum superconducting twisted wire

A niobium-aluminum precursor wire comprising:

• a rod-shaped core that is formed of a copper stabilizer or that is formed of a copper stabilizer and a non-copper stabilizer;
• a lamination that is wound around the core and that has a structure of overlapping an aluminum foil and a niobium foil;
• and a covering body that covers a periphery of the lamination, wherein the covering body is formed of the copper stabilizer or is formed of the copper stabilizer and the non-copper stabilizer, wherein a volume ratio of the copper stabilizer to the non-copper stabilizer, contained in the niobium-aluminum precursor wire is 0.5 or more and 2.0 or less;
• and the niobium-aluminum precursor wire satisfying, with respect to a total volume of the volume of the copper stabilizer contained in the core and the volume of the copper stabilizer contained in the covering body, the following conditions:
• (1) a volume percentage of the copper stabilizer contained in the core is in a range of 30% to 70%;
• and (2) a volume percentage of the copper stabilizer contained in the covering body is in a range of 70% to 30%, wherein a total of the volume percentage of the copper stabilizer contained in the core and the volume percentage of the copper stabilizer contained in the covering body is 100%.