Substrate for superconducting wire, method for manufacturing the same, and superconducting wire
This invention provides a substrate for a superconducting wire used for manufacturing a superconducting wire with excellent superconductivity and a method for manufacturing the same. Such substrate for a superconducting wire has crystal orientation of metals on the outermost layer, such as a c-axis orientation rate of 99% or higher and a Δφ of 6 degrees or less, and a percentage of an area in which the crystal orientation is deviated by 6 degrees or more from the (001) [100] per unit area is 6% or less.
1. A substrate for a superconducting wire, comprising a non-magnetic metal plate, a layer of copper or a copper alloy superposed on the non-magnetic metal plate, and an outermost protective layer consisting of a plated film of nickel or a nickel alloy formed on the layer of copper or the copper alloy, wherein the crystal orientation of the outermost protective layer exhibits
a c-axis orientation rate of 99% or higher,
a Δφ of 6 degrees or less, and
a percentage of an area in which the crystal orientation is deviated by 6 degrees or more from the (001) [100] per unit area of 6% or less, wherein the crystal orientation deviation is observed via the electron back scatter diffraction (EBSD) method.
2. A superconducting wire comprising the substrate for a superconducting wire according to claim 1 , an intermediate layer superposed thereon, and a superconducting layer superposed thereon.
3. The substrate for a superconducting wire according to claim 1 , wherein the substrate comprises the non-magnetic metal plate, the layer of copper containing 1% or less of an additional element superposed on the non-magnetic metal plate, and the outermost protective layer consisting of a plated film of nickel or a nickel alloy formed on the layer of copper.
4. A method for manufacturing a substrate for a superconducting wire according to claim 1 comprising:
laminating a non-magnetic metal plate and a copper or copper alloy foil through surface activation bonding to form a layer of copper or the copper alloy;
subjecting the layer of copper or the copper alloy to thermal treatment, so as to achieve
a c-axis orientation rate of 99% or higher,
a Δφ of 6 degrees or less, and
a percentage of an area in which the crystal orientation is deviated by 6 degrees or more from the (001) [100] per unit area of 6% or less, wherein the crystal orientation deviation is observed via the electron back scatter diffraction (EBSD) method; and
forming an outermost protective layer consisting of a plated film of nickel or a nickel alloy on the layer of copper or the copper alloy, wherein the outermost protective layer maintains the crystal orientation of the layer of copper or the copper alloy.
5. The method according to claim 4 , wherein the degree of gloss of the copper or copper alloy foil is 45 or less before lamination.