Superconducting wire, method for manufacturing superconducting wire, and MRI device

A method for manufacturing a superconducting wire, the method comprising the steps of:

• packing a mixed powder being a mixture of magnesium powder and boron powder into a first metal pipe;
• performing wire-drawing on the first metal pipe filled with the mixed powder;
• producing a composite wire by accommodating the first metal pipe subjected to the wire-drawing in a second metal pipe;
• performing wire-drawing on the composite wire;
• and
• generating MgB2 by performing heat treatment on the composite wire subjected to the wire-drawing,
• wherein the first metal pipe is formed of a metal to be a base material of the superconducting wire,
• the second metal pipe is a composite pipe including a high-thermal expansion metal layer formed of a high-thermal expansion metal being stainless steel and a stabilizing material layer formed of a stabilizing material being copper covering a periphery of the high-thermal expansion metal layer and stabilizing superconductivity, or a multiple pipe including a high-thermal expansion metal pipe formed of the high-thermal expansion metal accommodated in a stabilizing material pipe formed of the stabilizing material stabilizing superconductivity, and
• the high-thermal expansion metal has a higher thermal expansion coefficient at room temperature than the MgB2 and the metal to be the base material.