Superconducting wires and methods of making thereof

Abstract

Disclosed herein are superconducting wires. The superconducting wires can comprise a metallic matrix and at least one continuous subelement embedded in the matrix. Each subelement can comprise a non-superconducting core, a superconducting layer coaxially disposed around the non-superconducting core, and a barrier layer coaxially disposed around the superconducting layer. The superconducting layer can comprise a plurality of Nb 3 Sn grains stabilized by metal oxide particulates disposed therein. The Nb 3 Sn grains can have an average grain size of from 5 nm to 90 nm (for example, from 15 nm to 30 nm). The superconducting wire can have a high-field critical current density (J c ) of at least 5,000 A/mm 2 at a temperature of 4.2 K in a magnetic field of 12 T. Also described are superconducting wire precursors that can be heat treated to prepare superconducting wires, as well as methods of making superconducting wires.

What is claimed is: 
     
         1 . A superconducting wire comprising:
 a matrix comprising a Cu-based metal; and   at least one continuous subelement embedded in the matrix;   wherein each subelement comprises:
 a non-superconducting core; 
 a superconducting layer coaxially disposed around the non-superconducting core; and 
 a barrier layer coaxially disposed around the superconducting layer; 
   wherein the superconducting layer comprises a plurality of Nb 3 Sn grains stabilized by metal oxide particulates disposed therein, and   wherein the Nb 3 Sn grains have an average grain size of from 5 nm to 90 nm.   
     
     
         2 . The superconducting wire of  claim 1 , wherein the Nb 3 Sn grains have an average grain size of from 15 nm to 30 nm. 
     
     
         3 . The superconducting wire of any of  claims 1 - 2 , wherein the superconducting layer further comprises a dopant. 
     
     
         4 . The superconducting wire of  claim 3 , wherein the dopant comprises Ti, Ta, or a combination thereof. 
     
     
         5 . The superconducting wire of any of  claims 1 - 4 , wherein the superconducting layer has a high-field critical current density (J c ) of from 5,000 to 21,000 A/mm 2  at a temperature of 4.2 K in a magnetic field of 12 T. 
     
     
         6 . The superconducting wire of any of  claims 1 - 5 , wherein the superconducting layer has a high-field critical current density (J c ) of 9,500 A/mm 2  or more at a temperature of 4.2 K in a magnetic field of 12 T. 
     
     
         7 . The superconducting wire of any of  claims 1 - 6 , wherein the superconducting layer has a flux pinning force vs. field (F p -B) curve that peaks at from 0.2 to 0.5 times the irreversibility field (B irr ). 
     
     
         17 . The superconducting wire of any of  claims 1 - 7 , wherein the barrier layer comprises a Nb alloy, a Ta alloy, a Ti alloy, or a combination thereof. 
     
     
         9 . The superconducting wire of claim  8 , wherein the barrier layer comprises a Nb alloy, and the Nb alloy comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         10 . The superconducting wire of claim  8  or  9 , wherein the barrier layer comprises a Nb alloy, and the Nb alloy is selected from the group consisting of a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, and combination thereof. 
     
     
         11 . The superconducting wire of any of  claims 1 - 10 , wherein the metal oxide particulates comprise a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         12 . The superconducting wire of any of  claims 1 - 11 , wherein the metal oxide particulates comprise a metal oxide selected from the group consisting of ZrO 2 , Al 2 O 3 , TiO 2 , and combinations thereof. 
     
     
         13 . The superconducting wire of any of  claim 1 - 12 , wherein the diameter of each subelement is from 5 μm to 150 μm. 
     
     
         14 . A superconducting wire precursor comprising:
 a matrix comprising a Cu-based metal; and   at least one continuous subelement precursor embedded in the matrix;   wherein each subelement precursor comprises:
 a Sn-based metal core; 
 a Cu-based layer coaxially disposed around the Sn-based metal core; 
 a metal oxide layer coaxially disposed around the Cu-based layer; and 
 a Nb alloy layer coaxially disposed around the metal oxide layer. 
   
     
     
         15 . The superconducting wire precursor of  claim 14 , wherein the Nb alloy layer comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         16 . The superconducting wire precursor of  claim 14  or  15 , wherein the Nb alloy layer comprises a Nb alloy selected from the group consisting of a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, and combinations thereof. 
     
     
         17 . The superconducting wire precursor of any of  claims 14 - 16 , wherein the metal oxide layer comprises a metal oxide that has a lower oxidation potential than NbO 2 . 
     
     
         18 . The superconducting wire precursor of any of  claims 14 - 17 , wherein the metal oxide layer comprises a metal oxide comprising a metal selected from the group consisting of Sn, Cu, Zn, Nb, Fe, Ni, Cr, Co, W, and combinations thereof. 
     
     
         19 . The superconducting wire precursor of any of  claims 14 - 18 , wherein the metal oxide layer comprises a metal oxide selected from the group consisting of SnO 2 , CuO, ZnO, Nb 2 O 5 , and combinations thereof. 
     
     
         20 . The superconducting wire precursor comprising:
 a matrix comprising a Cu-based metal; and   at least one continuous subelement precursor embedded in the matrix;   wherein each subelement precursor comprises:
 a Sn-based metal core; 
 a Cu-based layer coaxially disposed around the Sn-based metal core; 
 a first Nb alloy layer coaxially disposed around the Cu-based layer; 
 a metal oxide layer coaxially disposed around the first Nb alloy layer; and 
 a second Nb alloy layer coaxially disposed around the metal oxide layer. 
   
     
     
         21 . The superconducting wire precursor of  claim 20 , wherein the first Nb alloy layer and the second Nb alloy layer each comprise an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         22 . The superconducting wire precursor of  claim 20  or  21 , wherein the first Nb alloy layer and the second Nb alloy layer each comprise a Nb alloy selected from the group consisting of a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, and combinations thereof. 
     
     
         23 . The superconducting wire precursor of any of  claims 20 - 22 , wherein the metal oxide layer comprises a metal oxide that has a lower oxidation potential than NbO 2 . 
     
     
         24 . The superconducting wire precursor of any of  claims 20 - 23 , wherein the metal oxide layer comprises a metal oxide comprising a metal selected from the group consisting of Sn, Cu, Zn, Nb, Fe, Ni, Cr, Co, W, and combinations thereof. 
     
     
         25 . The superconducting wire precursor of any of  claims 20 - 24 , wherein the metal oxide layer comprises a metal oxide selected from the group consisting of SnO 2 , CuO, ZnO, Nb 2 O 5 , and combinations thereof. 
     
     
         26 . A superconducting wire precursor comprising:
 a matrix comprising a Cu-based metal; and   at least one continuous subelement precursor embedded in the matrix;   wherein each subelement precursor comprises:
 a Sn-based metal core; 
 a Cu-based layer coaxially disposed around the Sn-based metal core; 
 a Nb alloy layer coaxially disposed around the Cu-based layer; 
 a metal oxide layer coaxially disposed around the Nb alloy layer; and 
 a barrier layer coaxially disposed around the metal oxide layer. 
   
     
     
         27 . The superconducting wire precursor of  claim 26 , wherein the Nb alloy layer comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         28 . The superconducting wire precursor of  claim 26  or  27 , wherein the Nb alloy layer comprises a Nb alloy selected from the group consisting of a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, and combinations thereof. 
     
     
         29 . The superconducting wire precursor of any of  claims 26 - 28 , wherein the barrier layer comprises a Nb alloy, a Ta alloy, a Ti alloy, or a combination thereof. 
     
     
         30 . The superconducting wire precursor of  claim 29 , wherein the barrier layer comprises a Nb alloy, and the Nb alloy comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         31 . The superconducting wire precursor of  claim 29  or  30 , wherein the barrier layer comprises a Nb alloy, and the Nb alloy is selected from the group consisting of a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, and combinations thereof. 
     
     
         32 . The superconducting wire precursor of any of  claims 26 - 31 , wherein the metal oxide layer comprises a metal oxide that has a lower oxidation potential than NbO 2 . 
     
     
         33 . The superconducting wire precursor of any of  claims 26 - 32 , wherein the metal oxide layer comprises a metal oxide comprising a metal selected from the group consisting of Sn, Cu, Zn, Nb, Fe, Ni, Cr, Co, W, and combinations thereof. 
     
     
         34 . The superconducting wire precursor of any of  claims 26 - 33 , wherein the metal oxide layer comprises a metal oxide selected from the group consisting of SnO 2 , CuO, ZnO, Nb 2 O 5 , and combinations thereof. 
     
     
         35 . A superconducting wire precursor comprising:
 a matrix comprising a Cu-based metal; and   at least one continuous subelement precursor embedded in the matrix;   wherein each subelement precursor comprises:
 a core comprising a blend of a Sn-containing powder and a metal oxide powder; and 
 a Nb alloy layer coaxially disposed around the core. 
   
     
     
         36 . The superconducting wire precursor of  claim 35 , wherein the Sn-containing powder comprises a Sn powder, a NbSn 2  powder, Nb 6 Sn 5  powder, or a combination thereof. 
     
     
         37 . The superconducting wire precursor of  claim 36 , wherein the Sn-containing powder further comprises Cu powder. 
     
     
         38 . The superconducting wire precursor of any of  claims 35 - 37 , wherein the Nb alloy layer comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         39 . The superconducting wire precursor of any of  claims 35 - 38 , wherein the Nb alloy layer comprises a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, or combinations thereof. 
     
     
         40 . The superconducting wire precursor of any of  claims 35 - 39 , wherein the metal oxide powder comprises a metal oxide that has a lower oxidation potential than NbO 2 . 
     
     
         41 . The superconducting wire precursor of any of  claims 35 - 40 , wherein the metal oxide powder comprises a metal oxide comprising a metal selected from the group consisting of Sn, Cu, Zn, Nb, Fe, Ni, Cr, Co, W, and combinations thereof. 
     
     
         42 . The superconducting wire precursor of any of  claims 35 - 41 , wherein the metal oxide powder comprises a metal oxide selected from the group consisting of SnO 2 , CuO, ZnO, Nb 2 O 5 , and combinations thereof. 
     
     
         43 . A superconducting wire precursor comprising:
 a matrix comprising a Cu-based metal; and   at least one continuous subelement precursor embedded in the matrix;   wherein each subelement precursor comprises:   a Sn-based metal core;
 a Cu-based layer coaxially disposed around the Sn-based metal core; 
 a Nb alloy layer coaxially disposed around the Cu-based layer, the Nb alloy layer further comprising a plurality of metal oxide regions disposed within the Nb alloy layer; and 
 a barrier layer coaxially disposed around the Nb alloy layer. 
   
     
     
         44 . The superconducting wire precursor of  claim 43 , wherein the Nb alloy layer comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         45 . The superconducting wire precursor of any of  claims 43 - 44 , wherein the Nb alloy layer comprises a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, or combinations thereof. 
     
     
         46 . The superconducting wire precursor of any of  claims 43 - 45 , wherein the barrier layer comprises a Nb alloy, a Ta alloy, a Ti alloy, or a combination thereof. 
     
     
         47 . The superconducting wire precursor of  claim 46 , wherein the barrier layer comprises a Nb alloy, and the Nb alloy comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb. 
     
     
         48 . The superconducting wire precursor of any of  claims 43 - 47 , wherein the plurality of metal oxide regions each comprise a metal oxide that has a lower oxidation potential than NbO 2 . 
     
     
         49 . The superconducting wire precursor of any of  claims 43 - 48 , wherein the plurality of metal oxide regions each comprise a metal oxide comprising a metal selected from the group consisting of Sn, Cu, Zn, Nb, Fe, Ni, Cr, Co, W, and combinations thereof. 
     
     
         50 . The superconducting wire precursor of any of  claims 43 - 49 , wherein the plurality of metal oxide regions each comprise a metal oxide selected from the group consisting of SnO 2 , CuO, ZnO, Nb 2 O 5 , and combinations thereof. 
     
     
         51 . The superconducting wire precursor of  claims 43 - 49 , wherein the a Nb alloy layer comprises a plurality of discrete Nb alloy rods, each Nb alloy rod comprising a Nb alloy core ensheathed in copper or a copper alloy. 
     
     
         52 . The superconducting wire precursor of  claim 51 , wherein the plurality of metal oxide regions comprise a plurality of metal oxide rods, each metal oxide rods comprising a metal oxide core ensheathed in copper or a copper alloy. 
     
     
         53 . The superconducting wire precursor of  claim 52 , wherein the metal oxide core comprises a metal oxide powder. 
     
     
         54 . The superconducting wire precursor of  claims 51 - 53 , wherein the Nb alloy rods are formed into hexed cross sectional rods, and wherein the Nb alloy layer comprises a plurality of hexagonally packed Nb alloy rods. 
     
     
         55 . The superconducting wire precursor of  claim 54 , wherein the metal oxide rods are formed into hexed cross sectional rods to enable their packing among the hexagonally packed Nb alloy rods. 
     
     
         56 . A method of making a superconducting wire comprising heat treating the superconducting wire precursor of any of  claims 14 - 55  to form a superconducting wire comprising a superconducting phase comprising Nb 3 Sn. 
     
     
         57 . The method of  claim 56 , wherein heat treating the superconducting wire precursor comprises heating the superconducting wire precursor at a temperature of at least 600° C. 
     
     
         58 . The method of  claim 56  or  57 , wherein heat treating the superconducting wire precursor comprises heating the superconducting wire precursor at a temperature of from 600° C. to 850° C. 
     
     
         59 . The method of any of  claims 56 - 58 , wherein heat treating the superconducting wire precursor comprises heating the superconducting wire precursor for at least 10 minutes. 
     
     
         60 . The method of any of  claims 56 - 59 , wherein heat treating the superconducting wire precursor comprises heating the superconducting wire precursor for from 10 minutes to 800 hours. 
     
     
         61 . A superconducting wire prepared by the method of any of  claims 56 - 60 . 
     
     
         62 . The superconducting wire of  claim 61 , wherein the superconducting wire comprises a superconducting phase that has a high-field critical current density (J c ) of from 5,000 to 21,000 A/mm 2  at a temperature of 4.2 K in a magnetic field of 12 T. 
     
     
         63 . The superconducting wire of any of  claims 61 - 62 , wherein the superconducting wire comprises a superconducting phase that has a high-field critical current density (J c ) of 9,500 A/mm 2  or more at a temperature of 4.2 K in a magnetic field of 12 T. 
     
     
         64 . The superconducting wire of any of  claims 41 - 43 , wherein the superconducting wire comprises a superconducting phase that has a flux pinning force vs. field (F p -B) curve that peaks at from 0.2 to 0.5 times the irreversibility field (B irr ). 
     
     
         65 . An electromagnetic device comprising at least one superconducting wire of any of  claims 1 - 13  or  61 - 64 .