Precursor wire for Nb3Al superconducting wire, Nb3Al superconducting wire, method for producing precursor wire for Nb3Al superconducting wire, and method for producing Nb3Al superconducting wire

Patent metadata

Field	Value
Publication number	US-9680081-B2
Application number	US-201213677622-A
Country	US
Kind code	B2
Filing date	Nov 15, 2012
Priority date	Nov 22, 2011
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

Problem
There is proposed an innovative cross-sectional structure, with an idea contrary to the conventional one, utilizing the non-reactivity between Cu and Ta (or between Ag and Nb, Ta) in a high-temperature short-time heat treatment, thus achieving (1) the suppression of the low magnetic-field instability, (2) excellent wire drawability of a precursor wire, and (3) the reduction of the cost required for the incorporation of a stabilizer.
Means for Resolution
There is proposed a structure having an assembly of a plurality of single wires, wherein the assembly is covered with an outer cover (skin) formed from Nb or Ta, wherein each of the single wires has an Nb/Al composite filament region which is formed from a composite of Nb and Al mixed in an Nb:Al molar ratio of 3:1, and which is covered with a partition formed from Nb or Ta, and further covered with an interfilamentary barrier formed from Cu or Ag disposed around the partition.

First claim

The invention claimed is:

1. A precursor wire for producing an Nb 3 Al superconducting wire by rapid-heating, quenching and transformation processes, comprising an assembly of a plurality of single wires, the assembly being covered with an outer cover (skin) formed from Nb or Ta,
wherein each of the single wires comprises an Nb/Al composite filament region which is formed from a composite of Nb and Al mixed in an Nb:Al molar ratio of 3:1, an interfilamentary barrier formed from Cu or Ag covered on the outside of the Nb/Al composite filament region for effectively electromagnetic decoupling of superconducting filaments, and a partition formed from Nb or Ta provided between the Nb/Al composite filament region and the interfilamentary barrier for preventing the interfilamentary barrier from reacting with the Nb/Al composite filament region to form a non-superconducting compound,
wherein the volume fraction of Cu or Ag in the single wire is 7 to 25%, and
wherein, when Cu is used as the interfilamentary barrier, Ta film having a thickness of 5 μm or more is used as the partition, and, when Ag is used as the interfilamentary barrier, Nb or Ta film having a thickness of 1 μm or more is used as the partition.

2. The precursor wire for producing Nb 3 Al superconducting wire according to claim 1 , wherein internal stabilizer filaments each formed from Cu or Ag and covered with an internal-stabilizer-filament-covering-layer formed from Nb or Ta are disposed inside the assembly.

3. The precursor wire for producing Nb 3 Al superconducting wire according to claim 1 , wherein dummy filaments each formed from Nb or Ta and covered with a dummy filament covering layer formed from Cu or Ag are disposed inside the assembly.

4. The precursor wire for producing Nb 3 Al superconducting wire according to claim 1 , wherein the assembly comprises Cu, and wherein the assembly is covered with the outer cover (skin) comprising Ta.

5. The precursor wire for producing Nb 3 Al superconducting wire according to claim 1 , wherein the assembly comprises Ag, and wherein the assembly is covered with the outer cover (skin) comprising Nb or Ta.

6. An Nb 3 Al superconducting wire which is obtained from the precursor wire for the Nb 3 Al superconducting wire according to claim 1 , wherein the Nb/Al composite filament regions have been converted to the Nb 3 Al filaments.

7. A method for producing an Nb 3 Al superconducting wire, comprising: subjecting the precursor wire for the Nb 3 Al superconducting wire according to claim 1 to heat treatment at 1,900° C. or higher for 5 seconds or less; quenching the resultant precursor wire to 500° C. or lower; and subjecting the quenched wire to additional heat treatment at 700 to 900° C.

Assignees

• Hitachi Cable
• Inter-University Res Inst Corp
• Nat Inst For Materials Science
• Nat Inst For Materials Science
• Inter-University Res Inst Corp High Energy Accelerator Res Organization

Inventors

• Takeuchi Takao
• Tsuchiya Kiyosumi
• Nakagawa Kazuhiko

Classifications

• Y10T428/12819

  Group VB metal-base component · CPC title

• H01B13/00

  Apparatus or processes specially adapted for manufacturing conductors or cables · CPC title

• H01B12/02

  characterised by their form · CPC title

• H01L39/2403

  Electricity · mapped topic

• H01L39/12 Primary

  Electricity · mapped topic