JPS60422B2 - Manufacturing method of Nb↓3Sn composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a N/Sn composite processed material for generating strong magnetic fields whose characteristics have been improved by adding silicon or further gallium or aluminum.

Superconducting wires are used as winding materials for electromagnets that generate strong magnetic fields because they can carry large currents without consuming power and can maintain their superconducting state even in strong magnetic fields.

Currently, the most widely used liner is Nb-Ti.
The magnetic field generated by the alloy wire is approximately 8
The limit is 15,000 Gauss (8.5 Tesla: 8.5T), and in order to generate a stronger magnetic field than this, it is necessary to use a compound-based superconductor with a high upper critical magnetic field (Hc2). However, the lack of plasticity inherent to the compound has been a major obstacle to its practical application. In recent years, methods using diffusion such as surface diffusion method and composite processing method have been developed one after another, and it has become possible to form a linear structure of Nb3Sn and V3Ga compounds and put them into practical use. What is surface diffusion method?
For example, an Nb tape is passed continuously through a molten tin (Sn) bath to deposit Sn on the tape surface, and then heat-treated at an appropriate temperature to cause a diffusion reaction between Nb and Sn, resulting in N on the tape surface.
This is a method of generating a b3Sn compound layer. The composite processing method refers to, for example, combining Nb and a copper (Cu)-Sn solid solution alloy, processing and heat treating the S in the Cu-Sn alloy.
This is a method of selectively reacting only n with Nb to form an Nb3Sn compound layer on the interface, and is a type of solid diffusion method. Since both the Nb and Cu-Sn solid solution alloy bodies have sufficient plasticity, they can be easily processed into any required shape, such as a wire or tapered tube, as a composite before being subjected to heat treatment. Furthermore, by embedding a large number of Nb rods in a Cu-Sn alloy matrix and performing pongee wire processing, an ultra-fine multicore wire rod that is stable against distant magnetic field changes can be obtained. Nb3Sn or V30a compound wires produced by such a surface diffusion method and a composite processing method are already used as small-sized strong magnetic field magnets for physical property research. On the other hand, in recent years, the development of large-scale strong magnetic field magnets for nuclear fusion reactors, high energy storage, superconducting generators, etc. has been progressing, and the superconducting wire used in these has a large critical current (
There is an urgent need to put into practical use ultra-fine multifilamentary compound wires that have lc) and are stable against distant changes in magnetic fields.

However, the critical current (lc) of a conventional N-rich Sn compound wire made from a composite of pure Nb and a Cu-Sn binary alloy decreases rapidly in a magnetic field of 1OT or more, and depending on this wire, the critical current (lc) decreases rapidly in a magnetic field of 12r or more. It has been difficult to create a superconducting magnet that can generate . On the other hand, V30a compound wire has better strong magnetic field characteristics than N-wide Sn, but the material is much more expensive than NGSn, so for large equipment that uses a large amount of wire, it is necessary to improve the strong magnetic field characteristics by using a small amount of alloy. It is better to use NQSn wire improved by adding elements. Recently, a binary alloy body in which hafnium (Hf) is dissolved in Nb and a Cu-Sn binary alloy or a ternary Cu-based alloy body in which Ga or AI is added are integrated, processed and heat-treated. A method for manufacturing a Nb3Sn compound wire with significantly improved superconducting properties in a strong magnetic field has been developed (Japanese Patent Application No. 112191/1982). Hf in the Nb alloy dissolves in the Nb3Sn phase and significantly increases the diffusion formation rate of the Nb3Sn layer, increasing the thickness of the Nb3Sn layer and increasing lc. In addition, Ga or AI added to the Cu-Sn alloy also diffuses into the NO alloy together with Sn and dissolves in the formed N-rich Sn phase to increase its Hc2. and GaL
Alternatively, the strong magnetic field characteristics of the N-wide Sn composite processed wire rod added with Hf and AI are significantly improved, and a large lc value is obtained even in strong magnetic fields. However, since the Hf used in the above invention is expensive, it has the disadvantage that the advantage of N and Sn wires, which are cheaper than V30a wires, is slightly impaired.Therefore, the strong magnetic field characteristics can be improved with cheaper additive elements. This was required as a condition for the practical application of Nb3Sn composite processed wire rods for strong magnetic fields that compete with V3Ga.In order to meet these requirements, the present invention has developed an Nb alloy with Si added, which is much cheaper than Hf. A composite of Cu-Sn, Cu-contacted Sn-Ga, or Cu-Sn-mountain alloy is processed into a predetermined shape and heat treated, and a strong magnetic field containing a small amount of Si, Ga, and peaks is applied to the interface of the composite. The purpose is to diffusely generate an N-wide Sn layer with improved characteristics.

All alloy contents in this specification are expressed in atomic percent. In the manufacturing method according to the present invention, first, an Nb-based alloy body containing Si as a solid solution is melted in order to promote the diffusion and formation of the Nb3Sn layer, and separately, a Cu-Sn alloy body or a Nb-based alloy body or an Nb-based alloy body is produced, which has the effect of increasing Hc2. Ga or AI with
The above-mentioned Nb-based alloy is coated with a Cu-based alloy to form composites of various shapes, and these are processed into wires, tapes, tubes, etc. by wire drawing, rolling, or tube drawing. Here, the S pupil added to Nb should be within the range of 0.1% or more to obtain excellent superconducting properties, and 3% or less to maintain good workability of the Nb-based alloy body. In particular, it is desirable that the content be within the range of 0.2 to 1%.Also, Cu-Sn-Ga or Cu-Sn-
The amount of Ga or AI in the AI alloy body should be 0.1% or more, respectively, to obtain excellent superconducting properties, and 15% or 18%, respectively, to maintain good workability of the Cu-based alloy body.
Must be within the range of % or less. Furthermore, the amount of Sn in the Cu-based alloy is 2% in order to obtain a sufficient thickness of the Nb3Sn layer.
``Also, it must be within the range of 9% or less to maintain good workability.Next, the processed material is heat treated to add Sn or a small amount of Ga or AI in addition to N.
It is diffused into the b-based alloy to form a Nb3Sn compound layer with excellent superconducting properties containing a small amount of Si or further Ga or AI at the interface of the composite. Here, the heat treatment for diffusion is performed at a temperature range of 600 to 900oC for 1 minute.
Do this within 20 feeding hours. Heat treatment at a lower temperature or for a shorter time will not produce a sufficient amount of N-rich Sn layer, and conversely, if the heat treatment is performed at a higher temperature or for a longer time, the Nb3S
The crystal grains of n become coarse and the superconducting properties deteriorate. The Nbbn composite processed wire to which Si or further Ga or AI is added obtained in the present invention has an increased critical current c and upper critical magnetic field Hc2 compared to the conventional N wide Sn wire, and as a result, in a strong magnetic field The improvement in lc is remarkable.

Therefore, the present invention enables various types of superconductor-based equipment to be used in strong magnetic fields with sufficient margin, and improves equipment performance, safety, and
It is also effective in improving reliability. Furthermore, Sj added to Nb to improve the strong magnetic field characteristics is
It is much cheaper than Hf, which is added for the same purpose, and the strong magnetic field characteristics of NGSn can be significantly improved without increasing the manufacturing cost, so its economic and technical effects are extremely large. In addition, since the present invention employs a composite processing method, it is stable against distant magnetic field changes, and
It is possible to produce ultra-fine multicore green material with low AC loss, and it is also easy to produce large capacity wires, making it possible to increase the size of equipment used. As described above, the Nb3Sn composite processed wire rod improved by the present invention can generate a strong magnetic field of 15 T or more with good stability, so it can be used for nuclear fusion reactors, high energy storage, superconducting generators, high energy physical accelerators, physical property research, etc. It can be effectively used as a winding material for various strong magnetic field magnets.

Example 1 A material containing pure Nb and Nb mixed with 0.3% to 0.51% Si was melted in an arc melting furnace in an argon atmosphere.
This was processed to a diameter of 3 ribs using grooved rolls and swaging to produce a Nb-Si alloy rod.

This was inserted into a Cu-7%Sn alloy tube with an outer diameter of 8 and an inner diameter of 3 ribs, and the composite was rolled to a thickness of approximately 25 mm using grooved rolls and flat rolls.
It was processed into a tape shape with a width of 0 rm and approximately 5 sails, and was heat-treated in an argon atmosphere at 800 qo for 10 hours. The results of measuring the thickness and Tc of the N wide Sn layer of the sample are shown in Table 1. Further, the measurement results of lc of representative samples among these samples were as shown in FIG. It can be seen that the addition of Si significantly increases the thickness of the N and Sn layer, and also significantly improves the lc characteristics in the entire magnetic field region. Table 1 Example 2 Nb-0.3 0. A composite of a 1% S waste metal rod and a Cu-5% Sn-4% Ga alloy tube was processed into a tape shape, and then heat-treated at 80,000 for 10 days.

The measurement results of the thickness and Tc of the N and Sn layers are shown in Table 1, and the measurement results of lc of representative samples among these samples are shown in FIG. The simultaneous addition of Si and OA increases Tc, and furthermore, the decrease in lc due to an increase in magnetic field becomes clearly smaller, and a large lc can be obtained in a strong magnetic field of 1 or more. This is considered to be because Hc2 increased with the rise in Tc. Example 3 A composite tape of Nb-0.3 0.5, 1% S waste metal body and Cu-5% Sn-4% AI alloy body was prepared in the same manner as in Example 2, and then fed with 800q0 for 10 times. Heat treatment was performed for an hour.

For N, the thickness of the Sn layer and the measurement results of Tc are shown in Table 1 above. Simultaneous addition of Si and AI increased Tc, and as in Example 2, an improvement in lc was obtained in a strong magnetic field.

[Brief explanation of drawings]

FIG. 1 shows the N wide S according to the present invention described in Examples 1 and 2.
It is a magnetic field-critical current curve when an n-composite processed wire is heat-treated at 800 qo for 100 hours. 1: Nb/Cu-7%Sn, 2: Nb-0.5%Si/
Cu-7%Sn, 3:Nb-1%Si/Cu-7%Sn
, 4:Nb-0.5%Si-Cu-5%Sn-4%Ga
, 5: Nb-1%Si, Cu-5%Sn-4%Ga. bag' figure

Claims (1)

[Claims] 1. An alloy body containing 0.1 to 3 atomic percent silicon in niobium;
A composite of copper and an alloy containing 2 to 9 at% tin is processed into a wire, tape, or tube shape by drawing, rolling, or tube drawing, and then heated at 600 to 900°C for 1 to 20 minutes.
A method for producing a processed Nb_3Sn composite material, which comprises performing heat treatment for 0 hours to generate a Nb_3Sn compound at the composite boundary. 2. An alloy body containing 0.1 to 3 atomic percent silicon in niobium,
A composite of copper with an alloy containing 2 to 9 at% tin and 0.1 to 15 at% gallium or 0.1 to 18 at% aluminum is made into a wire or tape by drawing, rolling, or tube drawing. Or after processing into a tubular shape, 600~900
Heat treatment was performed at ℃ for 1 minute to 200 hours to add Nb to the interface of the composite.
Nb_3S characterized by producing a _3n compound
n Manufacturing method for composite processed materials.