Process for producing compound based superconductor wire

Abstract

A process for producing a compound-based semiconductor wire having a high mechanical strength and which can be coiled so as to be cooled efficiently. A starting composition is formed by blending at least one metal powder selected from among Nb-based and V-based particles having at least a partial surface coating of an alloy or metal selected from Cu-Sn-based and Ga-based metal layers with at least one of Cu-based, Sn-based, Ga-based, Cu-Sn-based and Cu-Ga-based metal or alloy powder. The cross-sectional area of the composition is reduced followed by a heat treatment. The composition is then drawn into a wire of desired diameter.

What is claimed is: 
     
       1. A process for producing a Nb 3  Sn or V 3  Ga compound-based superconductor wire comprising the steps of: forming a composition by blending at least one metal powder selected from the group consisting of Nb-based and V-based particles at least part of the surface of which is covered with at least one layer selected from the group consisting of .[.Cu-Sn-based.]. .Iadd., in the case of Nb 3  Sn compound-based superconductor wire, Cu-based and Sn-based, and in the case of V 3  Ga compound-based superconductor wire, Cu-based .Iaddend.and Ga-based, metal layers with at least one metal powder or alloy powder selected from the group consisting of Cu-based, Sn-based, Ga-based, Cu-Sn based and Cu-Ga-based .Iadd.particles.Iaddend.; reducing the cross-sectional area of said composition; heat treating said composition; and drawing the heat-treated composition into a wire. 
     
     
       2. The process according to claim 1 wherein at least part of the surfaces of individual particles of said group consisting of Nb- and V-based metal particles is covered with an alloy layer selected from the group consisting of Cu-Sn-based and Cu-Ga-based alloy layers. 
     
     
       3. The process according to claim 1 or 2 wherein said metal powder comprises at least one metal powder selected from the group consisting of Nb- and .[.Ga-based.]. .Iadd.v-based .Iaddend.particles at least a part of the surface of which is covered with at least one layer selected from the group consisting of Cu-based, Sn-based, Ga-based, Cu-Sn-based and Cu-Ga-based layers, said particles being further covered with at least one layer selected from the group consisting of Sn-based, Ga-based, Cu-Sn-based and Cu-Ga-based layers. 
     
     
       4. The process according to claim 1 or 2 wherein said Nb-based and V-based metal particles are blended with particles selected from the group consisting of Cu-based, Cu-Sn-based, Cu-Ga-based particles, Nb-based composite particles, and V-based composite particles by forming individual metal or alloy layers into a desired shape at a temperature of from room temperature to 1050° C. and sintering, whereupon part of all of said metal or alloy layers on surfaces of adjacent metal layers are joined together. 
     
     
       5. The process according to claim 1 or 2 wherein said Nb-based and V-based metal particles are blended with particles selected from the group consisting of Cu-based, Cu-Sn-based, Cu-Ga-based particles, Nb-based composite particles, and V-based composite particles by extrusion at an extrusion temperature of from room temperature to 1050° C. with an extrusion ratio of more than 2, whereupon part of all of said metal or alloy layers on surfaces of adjacent metal layers are joined together. 
     
     
       6. The process according to claim 1 or 2 wherein said at least one layer selected from the group consisting of Cu-Sn-based and Cu-Ga-based alloy layers contains a material selected from the group consisting of tin in one of a range of from 0.1 to 14 wt % and from 50 to 100 wt %, and gallium in one of a range of from 0.1 to 25 wt % and from 50 to 100 wt %. 
     
     
       7. The process according to claim 1 or 2 wherein said step of heat treating comprises sintering in a vacuum to form a metallurgically integral bar. 
     
     
       8. The process according to claim 1 or 2 wherein said step of heat treating comprises hot extrusion.