PROBLEM TO BE SOLVED: To manufacture Nb3 (Al, Ge) or Nb3 (Al, Si) very thin multiple core super conductive wire having high critical current density by adding Ge or Si to an Nb3Al very thin multiple core wire.
SOLUTION: In this manufacturing method, a very thin multiple core structure composite wire is made by embedding tens to millions of composite core materials where Al-(2 to 3) at % Ge alloy with a thickness not more than 1 μm and a volume ratio of 1:2.5 to 1:3.5 is homogeneously composed into an Nb base material into a tube like matrix material made of Nb. A quick heating/ cooling processing where this composite wire is heated to 1700°C or more in two seconds or less, and is lead into a molten metal near a heat chamber for cooling forms a A15 phase compound filament with a low crystal order degree in the composite wire. In this state, the composite wire is covered with Cu as a superconductivity stabilizing material. An additional heating process at 650 to 900°C recovers the crystal order degree of the Nb3 (Al, Ge) which is a A15 phase compound.