Wires made of doped magnesium diboride powders and methods for making the same

Abstract

A wire having a metal matrix is provided. The wire further includes a plurality of filaments disposed in the metal matrix, where at least one of the plurality of filaments includes doped magnesium diboride powder. The doped magnesium diboride powder includes a first phase having a plurality of magnesium diboride particles having a chemical formula MgB 2-x S x , where x represents an atomic percentage, and wherein S represents carbon, boron, nitrogen, oxygen, or combinations thereof. The powder further includes a second phase surrounding each of the plurality of magnesium diboride particles, where the second phase includes a carbide, a nitride, an oxide, a boride, an oxy-nitride, an oxy-boride, an oxy-carbide, or combinations thereof.

1 . A wire comprising:
 a metal matrix; and   a plurality of filaments disposed in the metal matrix, at least one of the plurality of filaments comprising a doped magnesium diboride powder, comprising:
 a first phase having a plurality of magnesium diboride particles having a chemical formula MgB 2-x S x , wherein S represents a dopant, wherein S comprises carbon, nitrogen, boron, oxygen, or combinations thereof, and wherein x represents an atomic percentage of the dopant in the superconducting powder; and 
 a second phase surrounding each of the plurality of magnesium diboride particles, wherein the second phase comprises a carbide, a nitride, an oxide, a boride, an oxy-nitride, an oxy-boride, an oxy-carbide, or combinations thereof. 
   
   
   
       2 . The wire of  claim 1 , wherein the second phase comprises a plurality of particles, a thin film, or both. 
   
   
       3 . The wire of  claim 1 , wherein a length of the wire is in a range of about 10 cm to about 10 6  cm. 
   
   
       4 . The wire of  claim 1 , wherein a value of x is in a range of about 8 percent to about 10 percent. 
   
   
       5 . The wire of  claim 1 , wherein a size of the plurality of silicon carbide particles is in a range of from about 5 nanometers to about 50 nanometers. 
   
   
       6 . The wire of  claim 1 , wherein the wire is configured to experience a stress in a range of from about 50 MPa to about 500 MPa. 
   
   
       7 . The wire of  claim 1 , wherein the wire is configured to experience a strain in a range of from about −1% to about 1%. 
   
   
       8 . The wire of  claim 1 , wherein each of the plurality of filaments comprises a surrounding barrier layer. 
   
   
       9 . The wire of  claim 8 , wherein the barrier layer comprises one of stainless steel, steel, nickel or niobium or combinations thereof. 
   
   
       10 . The wire of  claim 1 , wherein the wire is twisted. 
   
   
       11 . The wire of  claim 1 , wherein the wire has a twist pitch in the range of approximately 20 mm to approximately 200 mm. 
   
   
       12 . A method of making a wire comprising:
 filling a hole in a metal tube with doped magnesium diboride powder, comprising:
 a first phase having a plurality of magnesium diboride particles having a chemical formula MgB 2-x S x , wherein S represents a dopant, wherein S comprises carbon, nitrogen, boron, oxygen, or combinations thereof, and wherein x represents an atomic percentage of the dopant in the superconducting powder; 
 a second phase surrounding each of the plurality of magnesium diboride particles, wherein the second phase comprises a carbide, a nitride, an oxide, a boride, an oxy-nitride, an oxy-boride, an oxy-carbide, or combinations thereof, 
 sealing the ends of the metal tube; and 
 deforming the metal tube to increase the length of the metal tube. 
   
   
   
       13 . The method of  claim 12 , wherein particles of the doped magnesium diboride powder are in the form of rods, pellets, powder, particles, flakes, or combinations thereof. 
   
   
       14 . The method of  claim 12 , wherein the metal tube comprises copper, copper alloys, stainless steel, tantalum, magnesium, nickel alloys, or combinations thereof. 
   
   
       15 . The method of  claim 12 , wherein the ratio of a radius of the hole to the radius of the tube is about 0 1 to about 0.99, prior to the deforming. 
   
   
       16 . The method of  claim 12 , wherein the deforming is by extrusion, forging, rolling, swaging, drawing or combinations thereof. 
   
   
       17 . The method of  claim 12 , further comprising heat-treating the wire at a temperature of greater than or equal to about 600° C. for a time period of greater than or equal to about 1 hour. 
   
   
       18 . The method of  claim 12 , further comprising surrounding the metal tube with a barrier layer. 
   
   
       19 . The method of  claim 12 , further comprising twisting the wire such that the wire has a twist pitch in the range of approximately 20 mm to approximately 200 mm. 
   
   
       20 . A method for making a wire comprising
 contacting a first end of a first superconducting wire with a second end of a second superconducting wire, wherein the superconducting wire comprises a superconducting filament having a superconducting composition comprising doped magnesium diboride; and   heating the first end of the first superconducting wire with the second end of the second superconducting wire at a point to form a joint, wherein the superconducting filament having the superconducting composition is in continuous electrical contact with any other part of the superconducting filament after the formation of the joint.   
   
   
       21 . The method of  claim 20 , wherein the heating comprises heating via electron beams, ultrasound, laser beams, plasma arc, electrical resistive heating, or combinations thereof. 
   
   
       22 . The method of  claim 20 , wherein the heating comprises heating to temperatures in the range of about 600° C. to about 1000° C. 
   
   
       23 . The method of  claim 20 , further comprising adding a magnesium diboride powder or a combination of magnesium and boron to the point at which the first end of the first superconducting wire and the second end of the second superconducting wire are in a contact with one another. 
   
   
       24 . The method of  claim 20 , further comprising additionally heating the point to form a weld. 
   
   
       25 . The method of  claim 20 , further comprising heat-treating the joint to improve the superconductivity. 
   
   
       26 . The method of  claim 20 , wherein the wire after heating has a total length of greater than or equal to about 10668000 cm.