National Institute for Materials Science

National Research Institute for Metals

National Institute of Advanced Industrial Science and Technology

Japan As Represented by Director General of National Research Institute for Metals

Yasuo Iijima

Kiyoshi Inoue

Akihiro Kikuchi

Takao Takeuchi

Yuji Yoshida

Kyoji Tachikawa

Hitoshi Kitaguchi

Kikuo Itoh

Hisashi Sekine

Kazuto Hirata

Michio Kosuge

The present disclosure provides a copper-coated aluminum wire material including an aluminum wire material and a copper thin film coating the aluminum wire material that a space factor of the thin copper film is in the range of 0.2% to 4%.

Copper-coated aluminum wire material and production method therefor

A alloy (Mg&#x2014;X) of metal (X) and Mg in a liquid phase is made to react with B in a solid phase at a low temperature to manufacture a superconductor, which contains a large amount of MgBpotential for MRI, linear motorcar, superconducting cavity, electric power transmission cable, high-magnetic field magnet for medical units, electric power storage (SMES), and the like and is formed in the shape of bulk, wire, and foil, by heat treatment performed at a low temperature for a short time and at low cost.

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A superfine multi-core NbAl superconductive wire is produced by getting a NbAl superconductive wire ready which was obtained by subjecting a precursor wire having a superfine multi-core structure in which a plurality of Nb/Al complex cores are embedded in Nb, Ta, a Nb based dilute alloy, or a Ta based dilute alloy as the matrix to a rapid heating and quenching treatment comprising rapidly heating to a temperature range near 2,000&#xb0; C. in 2 seconds,

By rapidly heating a precursor wire having a multifilamentary structure in which multiple composite cores in which a composite compound of an Nb&#x2014;Ga compound and Nb is embedded in Nb are embedded in Nb, Ta, Nb-base alloy or Ta-base alloy as a matrix material to a temperature range of 1400 to 2100&#xb0; C. in 2 seconds, quenching the precursor wire at a rate of 5000&#xb0; C./second or larger, and subjecting the precursor wire to additional heat treatment at a temperature range of 600 to 850&#xb0; C. for 1 to 400 hours, a superconducting wire having a multifilamentary structure in which multiple composite cores in which a composite compound containing NbGa of a stoichiometric composition embedded in Nb are embedded in Nb, Ta, Nb-base alloy or Ta-base alloy as a matrix material is obtained.

Nb3Ga multifilamentary superconducting wire and process for preparing the same

A high-performance Nb Al extra-fine multifilamentary superconducting wire is produced simply and inexpensively through the improvement of critical values, Tc, Hc and Jc, without the addition of third elements such as Ge, Si and Cu. A first rapid heating and quenching treatment is applied to an Nb/Al composite wire having an atomic ratio of Al to Nb from 1:2.5 to 1:3.5 and having an extra-fine multifilamentary structure to form a BCC alloy phase comprising Nb with Al supersaturatedly dissolved therein wherein the treatment comprises heating the composite wire up to a temperature not lower than 1900&deg; C. within two seconds and then introducing it into a molten metal at a temperature not higher than 400&deg; C. to rapidly quench it. The wire is subjected to a second rapid heating and quenching treatment to form an A15-Nb Al compound having a low degree of crystalline order but having an approximately stoichiometric composition wherein the second treatment comprises heating the wire up to a temperature not lower than 1500&deg; C. within two seconds and then introducing it into a molten metal at a temperature not higher than 400&deg; C. Then, an additional heat treatment is conducted to improve the degree of crystalline order of the Al5-Nb Al compound having an approximately stoichiometric composition.

Process for the production of Nb3A1 extra-fine multifilamentary superconducting wire

A Cu-containing Nb Al multifilamentary superconductive wire having a multifilamentary (superfine multi-core structure that a large number of micro-complex cores each obtained by complexing a Cu&mdash;Al alloy containing Cu in an amount of more than 0.2 at. % and at most 10 at. % in Nb are embedded in Nb, Ta, an Nb alloy or a Ta alloy as a matrix, wherein in the micro-complex cores, an A15 phase compound structure is formed by rapid heating at a temperature of 1,700&deg; C. or more for 2 seconds or less and quenching to approximately room temperature, and further additionally heat-treated at a temperature of 650 to 900&deg; C. This superconductive wire has high Jc in a low magnetic field, can be applied to all magnetic fields of 29 T or less, and is excellent in Jc characteristics in a high magnetic field in comparison with an Nb Al wire.

CU-containing NB3A1 multifilamentary superconductive wire and process for producing the same

A process for producing an ultrafine multifilamentary superconducting Nb (Al,Ge) wire capable of generating a high critical current density comprising: preparing a composite core material comprising an A1&mdash;(2-30)at. % Ge alloy (where at. % represents % by atomic) 1 &mgr;m or less in thickness uniformly incorporated into a Nb matrix at a volume ratio in a range of 1:2.5 to 1:3.5 and forming a composite therewith; fabricating a composite wire having an ultrafine multifilamentary structure by embedding several tens to several millions of the resulting composite core materials in a cylindrical matrix material containing Nb; forming a A15-phase filament having a lower order in crystallinity inside the composite wire by a rapid heating and quenching treatment comprising rapidly heating to a temperature of 1,700&deg; C. or higher in 2 seconds, followed by continuously introducing it into a molten metal; coating the composite wire with copper (Cu) which functions as a superconductivity stabilizing material; and applying a post heat treatment in the temperature range of from 650 to 900&deg; C. to the resulting product to recover the degree of crystallinity of the Nb (Al,Ge) in the A compound.

Process for producing ultrafine multifilamentary Nb3(A1,Ge) or Nb3(A1,Si) superconducting wire

A long, linear composite article which is characterized in that a large number of composite filaments are present as spaced from one another in a continuous layer composed of copper, a copper alloy, niobium, tantalum or vanadium, each of said composite filaments having a structure that at least one strand of a linear body is surrounded by an aluminum alloy or niobium, said linear body being composed substantially of extremely fine, filamentary superconducting Nb.sub.3 Al compound having an average diameter of from about 0.03 .mu.m to about 1 .mu.m. The said composite article can be prepared by drawing a composite material composed of (a) an aluminum alloy and (b) niobium, together with copper or a copper alloy once or plural times repeatedly, until the average diameter of the aluminum alloy of (a) becomes about 1 .mu.m or less, and heat-treating the resultant linear composite material. This composite articles exhibit excellent superconducting characteristics in high-magnetic field and alternating-current magnetic field.

Multifilament Nb.sub.3 Al superconducting linear composite articles

In a process for producing at least one Nb.sub.3 Sn superconductor which comprises drawing a composite composed of a core of niobium or a niobium alloy and a matrix of a copper-tin alloy and subjecting the drawn composite to reactive heat-treatment, thereby forming a layer of Nb.sub.3 Sn between the core and the matrix; the improvement wherein the copper-tin alloy contains 1 to 15 atomic percent of tin, and 0.1 to 8 atomic percent in total of at least one element selected from 0.1 to 8 atomic percent of titanium, 0.1 to 5 atomic percent of zirconium and 0.1 to 5 atomic percent of hafnium.

Growing community of inventors

Ibaraki, Japan

Yasuo Iijima