Precursor for fabricating Nb3Sn superconducting wire, and Nb3Sn superconducting wire, and method for fabricating same

摘要

A method for fabricating a Nb3Sn superconducting wire includes the steps of loading or inserting a core material containing at least Sn into a pipe member made of Nb or a Nb alloy, inserting the pipe member into a Cu billet to form a composite member, subjecting the composite member to diameter reduction, and then heat-treating the composite member to form a Nb3Sn superconducting layer from the inner surface of the pipe member, wherein, in the pipe member made of Nb or the Nb alloy after the diameter reduction, the average crystal grain size is 0.1 to 2 µm, and preferably, the total concentration of oxygen, nitrogen, and carbon is 120 ppm or less.