CN103633529B - A kind of Nb3Al superconducting joint preparation method - Google Patents

A kind of Nb3Al superconducting joint preparation method Download PDF

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CN103633529B
CN103633529B CN201310613098.3A CN201310613098A CN103633529B CN 103633529 B CN103633529 B CN 103633529B CN 201310613098 A CN201310613098 A CN 201310613098A CN 103633529 B CN103633529 B CN 103633529B
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superconducting
powder
superconducting line
superconducting joint
heat treatment
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CN103633529A (en
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程军胜
王秋良
刘建华
戴银明
朱光
胡新宁
周峰
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Institute of Electrical Engineering of CAS
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Abstract

A kind of Nb 3al superconducting joint preparation method, preparation process is: choose the material powder that component comprises pure Nb and pure Al or Nb-Al alloy and pure Al, Nb-Al over-saturation solid solution alloy powder is prepared into, by the Nb of Nb-Al over-saturation solid solution alloy powder and over-saturation solid solution state to be connected by high-energy ball milling mode 3the end of Al superconducting line presoma is packed in junction block together, and carries out pre-compacted to powder, subsequently by overall for junction block together with Nb 3al superconducting line presoma is together heat-treated.Nb is made after heat treatment completes 3al superconducting joint.

Description

A kind of Nb3Al superconducting joint preparation method
Technical field
The present invention relates to a kind of superconducting line method of attachment, particularly a kind of Nb being applicable to rapid heating and cooling quenching transformation method and obtaining 3the superconducting joint preparation method of Al superconducting line.
Background technology
High field super magnet plays in technical fields such as such as nulcear magnetic resonance (NMR), ITER thermonuclear fusion, high-energy physics accelerators the important application that can not be substituted.In existing superconducting magnet technology of preparing, 10T and adopt the NbTi alloy superconducting line coiling of mechanical ductility excellence to form with lower magnet.Because the critical magnetic field of NbTi alloy is lower, the more highfield of more than 10T then needs to use the A-15 type intermetallic compound superconductor possessing more upper critical magnetic field characteristic to build magnet.The many employings of existing 10-20T magnet are by the NbTi alloy of cryogenic superconductor and Nb 3the nested formation of hybrid coil of Sn superconductor.A-15 type intermetallic compound Nb 3sn superconductor has good economy and higher technology maturity, but its shortcoming is critical limited capacity, and mechanical performance is especially fragile.High field magnet coil requires can maintain higher current density bearing larger stress while, belongs to the Nb of the intermetallic compound of A-15 type crystal structure together 3al compares Nb 3sn possesses the technological merits such as superconducting critical performance is high, stress sensitivity is low, radiation-resistant property is good, is expected to the important materials becoming high-field nuclear magnetic resonance spectrometer superconducting magnet and commercialization in future thermonuclear fusion device high field super magnet.Nb 3the technology of preparing of Al superconductor strand mainly comprises: solid-state diffusion method, laser/electron beam heating and quench method etc.Wherein, rapid heating and cooling quenching transformation method is the Nb that after Nb/Al mixing multifibres wire is heated rapidly to about 1800 DEG C, Quenching Treatment obtains over-saturation solid solution state 3al superconducting line presoma, and then carry out about 800-900 DEG C diffusion heat treatments and obtain Nb 3al superconducting line.Because over-saturation solid solution state material has good room temperature ductility, being very convenient to coil winding, is therefore current a kind of main Nb 3al superconducting line preparation method.
At Nb 3need in the actual building course of Al magnet to carry out joint reason to coil, the connection of superconducting line is one of key technology in magnet building course.These joint location comprise: the interlayer of superconducting coil connects, the connection etc. of connection between multi-coil and magnet coil and current feed.For Nb 3the requirement of Al superconducting joint performance, joint must possess excellent mechanical strength, to tackle the prestressing force, bending stress, electromagnetic stress, shrinkage stress etc. of magnet on the one hand.On the other hand, joint also must have lower resistance, especially the superconducting magnet of operation with closed ring, and connection resistance will cause the decay in magnetic field.Such as in nuclear magnetic resonance spectrometer (NMR) magnet, require that magnetic field keeps high uniformity and time scale keep superregulated property on particular space size distribution, improve signal to noise ratio and the scanning resolution of system with this.Wherein, the uniformity of space scale mainly relies on Electromagnetic Design and accurate technique for coiling guarantee; Stability in time scale is then rely on superconducting switch to connect magnet the two poles of the earth by superconducting joint, and make magnet under closed loop states, be able to constant current state and run, the stability maintaining magnetic field by reducing magnet current decay ensures.When connection resistance is constant, the magnetic field intensity of closed loop magnet exponentially decays.Connection resistance is larger, and field decay is faster.Usually, when NMR magnetic connectors resistance is less than 10 -11during Ω, system loss rate just can be made to be less than 0.02ppm/hour, ensure NMR system stable operation.Therefore controlling magnetic field decay needs to achieve the goal by reducing connection resistance as far as possible.
Nb 3the prior art aspect of Al joint, existing only have the T.Fukuzaki of Japanese RIKEN to propose to adopt solder method to prepare Nb 3al superconducting line joint, but be limited by its superconduction solder compositions and process conditions, and the critical back surface field of joint can only reach 0.4T, and actual available back surface field can only reach 0.1T, and harsh to actual joint instructions for use.Nb prepared by existing employing solder method 3in Al superconducting joint, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb 3nb in Al superconducting line 3al core → Nb 3nb matrix → the Nb of Al superconducting line 3the Nb on Al superconducting line surface 3sn layer → SnPbBi solder → Nb 3the Nb on Al superconducting line surface 3sn layer → Nb 3nb matrix → the Nb of Al superconducting line 3nb in Al superconducting line 3al core; Current spread direction along wire termination is: Nb 3nb in Al superconducting line 3al core → SnPbBi solder → Nb 3nb in Al superconducting line 3al core.All need through SnPbBi solder material in above-mentioned two paths, although SnPbBi solder also has certain superconductivity at low temperatures, its superconducting critical poor-performing, especially its critical back surface field is lower, will lose superconductivity, thus have influence on Nb under High-Field 3the performance of Al superconducting coil.And electric current needs through twice Nb along on the radial propagation direction of conductor side 3sn layer, Nb 3although Sn superconductor possesses good superconductivity, compare Nb 3the critical performance of Al superconductor is slightly poor, and critical magnetic field and critical current are all than Nb 3al superconductor is low, and stress sensitivity is higher, easily produces the critical performance degradation that stress causes.
Summary of the invention
The object of the invention is to overcome prior art Nb 3in Al superconducting line superconducting joint technology of preparing, the problem such as quality instability, the complicated harshness of process conditions, proposes a kind of new Nb 3al superconducting line joint preparation method.The inventive method is easy, steady quality, can reduce connection resistance.The present invention can be applicable to the manufacture process of high-field nuclear magnetic resonance spectrometer superconducting magnet and commercialization in future thermonuclear fusion device high field super magnet.
Technical program of the present invention lies in:
A kind of Nb 3al superconducting joint preparation method, its preparation process is: choose the material powder that particle diameter is 20-200 micron, and the component of material powder comprises pure Nb and pure Al, or Nb-Al alloy and pure Al, and the atomic quantity proportioning of Al and Nb in material powder is 3:1; Material powder is put into the grinding jar of agate or corundum ball material, put into the abrading-ball identical with grinding jar material simultaneously, and put into odium stearate powder as dispersant, be prepared into Nb-Al over-saturation solid solution alloy powder by high-energy ball milling mode; Removing Nb 3the sheathing material of Al superconducting line presoma.By the Nb of Nb-Al over-saturation solid solution alloy powder and over-saturation solid solution state to be connected 3the end of Al superconducting line presoma is packed in junction block together, and carries out pre-compacted to powder, and pressure range is 5-20MPa; Subsequently by junction block together with Nb 3al superconducting line presoma is together heat-treated, and system of heat treatment process is: be first heated to 180 DEG C of insulations 2 hours, the insulation of this temperature is to be volatilized totally by the odium stearate dispersant of powder surface, be beneficial to the sinter bonded of powder; Be warming up to 800-900 DEG C again, insulation 10-80 hour, the insulation of this temperature is to make Nb-Al atoms permeating and Nb 3the formation of Al superconduction phase transformation, Nb in this temperature 3al superconducting phase will generate; Control heat-treatment furnace temperature subsequently and progressively cool to room temperature, Slow cooling is the Nb in order to make preparation 3al superconducting joint and Nb 3the Stress-strain concentration that variations in temperature causes is reduced in Al superconducting line inside as far as possible, causes the damage of superconductivity; Heat treatment temperature error 3 DEG C, is convenient to accurately control superconduction phase transformation process; Dock the external pressure that the powder in head tube can continue in heat treatment process, also can not apply external pressure.Nb is made after heat treatment completes 3al superconducting joint.
Wherein, high-energy ball milling comprises planetary type ball-milling, stirring-type ball milling, oscillatory type ball milling.
Wherein, heat treatment atmosphere is vacuum, and vacuum degree is less than or equal to 1 × 10 -2pa, or slumpability gas, as argon gas atmosphere.
Wherein, whole Nb 3al superconducting joint preparation process can be carried out in vacuum environment, and vacuum degree is less than or equal to 1 × 10 -2pa.
Wherein, the Nb of over-saturation solid solution state 3al superconducting line presoma refers to and adopts rapid heating and cooling quenching conventional at present to change the standby Nb of legal system 3a kind of intermediateness of Al superconducting line.The material of a kind of Nb-Al supersaturated solid solution state that Quenching Treatment obtains after specifically Nb/Al mixing multifibres wire being heated rapidly to about 1800 DEG C, the over-saturation solid solution in Nb crystal of Al atom exists.Nb subsequently 3al superconducting line presoma also needs to carry out 800 DEG C of diffusion heat treatments, makes the Al atom in Nb-Al supersaturated solid solution and Nb atoms permeating generate Nb 3al Compound Phase, finally obtains the Nb possessing superconducting characteristic 3al superconducting line.Nb 3the Nb of Al superconducting line presoma and end-state 3al superconducting line is compared, and its advantage is that it has good room temperature ductility, is very convenient to coil winding, Nb 3al superconducting coil is all generally at Nb 3after first carrying out turning to type under Al superconducting line presoma state, then carry out diffusion heat treatments and finally obtain Nb 3al superconducting coil.In general Nb 3al superconducting line producer is at Nb 3can first to Nb before Al superconducting line product export 3al superconducting line carries out the Nb processing obtained described over-saturation solid solution state 3al superconducting line presoma.During use, by the Nb of above-mentioned over-saturation solid solution state 3after Al superconducting line presoma turns to coil, then carry out about 800-900 DEG C diffusion heat treatments and obtain containing A-15 type Nb 3the Nb of Al superconducting phase 3al superconducting coil.
Adopt Nb prepared by the present invention 3al superconducting joint is column construction, and it is respectively from the inside to the outside: Nb to be connected 3al superconducting line and be wrapped in Nb 3the Nb of Al superconducting line exterior circumferential 3al sinters block, Nb 3the outside that Al sinters block is junction block, holds Nb in junction block 3al superconducting line and Nb 3al sinters block.Junction block one end closure, the other end is uncovered; The tube wall of junction block is double-decker, and internal layer material is Ta, and skin is Cu.
Wherein, Nb 3al to sinter block and is through prepared by powder sintering process, inner flawless, and Nb 3al sinters block and Nb to be connected 3the contact interface place bonding state of Al superconducting line end is metallurgical binding.
Wherein, the purity 99.99% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.999% of the outer Cu of tube wall of junction block, thickness 1mm.The effect of Cu layer is shunting, at superconducting joint once when quench, by excessive current distributing at Cu layer, instantaneous temperature can be prevented excessive, burn superconducting joint or superconducting line.Ta layer is diffusion barrier layer, and effect is that superconducting joint is when diffusion in vacuum heat treatment, prevents the alloying element in the dusty material in junction block from entering in Cu layer by solid-state diffusion effect, reduces the purity of Cu, causes the separation capacity of Cu layer to decline.
Wherein, the length of junction block is not less than 40mm, the Nb in junction block 3al sinters block and Nb to be connected 3the connecting length of Al superconducting line is not less than 30mm.
Wherein, Nb 3the end of Al superconducting line is inclined-plane, Nb to be connected 3al superconducting line tries one's best, and the inclined-plane of these ends is face-to-face placement, or approximate placement face-to-face.
Feature of the present invention is:
By Nb 3al superconducting joint preparation process and Nb 3the heat treatment process of Al superconducting line combines, and synchronously completes, and has very strong operability and practicality.Nb 3al superconducting joint can must be prepared after superconducting coil coiling and assembling, and preparation process is subject to actual field condition and limits, with the Nb in factory 3al superconducting line preparation process is different.From Nb-Al equilbrium phase diagram, the Nb of stable stoichiometric proportion 3al superconducting phase could can only obtain more than 1600 DEG C.Therefore wire Nb 3the acquisition of Al superconducting phase generally need adopt non-equilibrium technology of preparing, is generated from supersaturated solid solution by atomic heat diffusion.Employing high-energy ball-milling process can obtain the nonequilibrium state Nb-Al supersaturated solid solution alloy powder away from thermodynamical equilibrium.Again Nb-Al supersaturated solid solution alloy powder is wrapped up compacted together superconducting line to be connected subsequently, adopt powder metallurgy technology at Nb 3in the diffusion heat treatments process of Al superconducting line presoma, by Nb to be connected 3al superconducting line is sintered to one, and generates Nb in the lump by atoms permeating effect 3al superconducting phase, thus realize Nb 3the superconduction of Al superconducting line connects, and makes superconducting joint.
Compared to existing technology, the structure of superconducting joint of the present invention plays the effect reducing connection resistance.
The Nb that the soldering legal system of prior art is standby 3in Al superconducting joint, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb 3nb in Al superconducting line 3al core → Nb 3nb matrix → the Nb of Al superconducting line 3the Nb on Al superconducting line surface 3sn layer → SnPbBi solder → Nb 3the Nb on Al superconducting line surface 3sn layer → Nb 3nb matrix → the Nb of Al superconducting line 3nb in Al superconducting line 3al core; Current spread direction along wire termination is: Nb 3nb in Al superconducting line 3al core → SnPbBi solder → Nb 3nb in Al superconducting line 3al core.All need through SnPbBi solder material in above-mentioned two paths, although SnPbBi solder also has certain superconductivity at low temperatures, its superconducting critical poor-performing, especially its critical back surface field is lower, will lose superconductivity, thus have influence on Nb under High-Field 3the performance of Al superconducting coil.And electric current needs through twice Nb along on the radial propagation direction of conductor side 3sn layer, Nb 3although Sn superconductor possesses good superconductivity, compare Nb 3the critical performance of Al superconductor is slightly poor, and critical magnetic field and critical current are all than Nb 3al superconductor is low, and stress sensitivity is higher, easily produces the critical performance degradation that stress causes.
Superconducting joint technology of the present invention will generate the Nb of superconduction after Nb-Al supersaturated solid solution sintering alloy powder 3al sintered body, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb 3nb in Al superconducting line 3al core → Nb 3nb matrix → the Nb of Al superconducting line 3al sinters block → Nb 3nb matrix → the Nb of Al superconducting line 3nb in Al superconducting line 3al core; Current spread direction along wire termination is: Nb 3nb in Al superconducting line 3al core → Nb 3al sinters block → Nb 3nb in Al superconducting line 3al core.Nb is used in current path in the present invention 3al sinters block and instead of Nb 3sn layer and SnPbBi solder, obvious Nb 3the superconduction critical electric current of Al material and critical back surface field are all than Nb 3sn and SnPbBi material is high, with Nb to be connected 3the critical performance of Al superconducting line is basically identical, improves joint current carrying capacity and critical back surface field.Further, the Nb adopting sintering process to prepare 3al sintered material is the transformation method Nb that quenches with rapid heating and cooling 3the heat treatment process of Al superconducting line completes simultaneously, Nb 3al sintered material and Nb 3al superconducting line surface will produce metallurgical binding in heat treatment process, greatly reduce connection resistance.
Further, preparation process and other processing steps of the supersaturated solid solution powder in the present invention are relatively independent, can complete in advance, with Nb in other experiment place 3preparation and the heat treatment process of Al superconducting coil are not conflicted.Further, the preparation of supersaturated solid solution powder stores after can once preparing, and uses in batches.Can ensure like this to control the unified of supersaturated solid solution powder properties.
Accompanying drawing explanation
Fig. 1 Nb 3al superconducting joint preparation flow block diagram,
Wherein, the block diagram content of dotted line is Nb 3the Standard processing protocol (part) of Al superconducting line factory, the block diagram content of solid line is content flow of the present invention;
The Nb that the soldering legal system of Fig. 2 prior art is standby 3longitudinal cross-section and the electric current of Al superconducting joint flow through path schematic diagram;
Fig. 3 Nb of the present invention 3the composition schematic diagram of Al superconducting joint before diffusion heat treatments;
Fig. 4 Nb of the present invention 3the composition schematic diagram of Al superconducting joint after diffusion heat treatments;
Fig. 5 Nb of the present invention 3longitudinal cross-section and the electric current of Al superconducting joint flow through path schematic diagram;
Fig. 6 prepares high-energy ball milling Nb by planetary type ball-milling mode 3the principle schematic of Al supersaturated solid solution powder;
Fig. 7 prepares high-energy ball milling Nb by stirring-type ball milling method 3the principle schematic of Al supersaturated solid solution powder;
Fig. 8 prepares high-energy ball milling Nb by oscillatory type ball milling method 3the principle schematic of Al supersaturated solid solution powder.
Embodiment
The present invention is further illustrated below in conjunction with the drawings and specific embodiments.
Nb of the present invention 3flow process prepared by Al superconducting joint is: choose the material powder that particle diameter is 20-200 micron, and the composition of material powder comprises pure Nb and pure Al, or Nb-Al alloy and pure Al, and the atom number proportioning of Al and Nb in material powder is 3:1; Add odium stearate dispersant, material powder is carried out high-energy ball milling preparation, make Nb-Al supersaturated solid solution powder.Removing Nb 3the sheathing material of Al superconducting line presoma; By the Nb of Nb-Al supersaturated solid solution powder and over-saturation solid solution state to be connected 3the end of Al superconducting line presoma is together packed in junction block, and carries out pre-compacted to powder, and pressure range is 5-20MPa.Subsequently by overall for junction block together with Nb 3al superconducting line presoma is together put into vacuum furnace and is carried out vacuum heat, is first heated to 180 DEG C of insulations 2 hours, then is increased to heat treatment temperature point, temperature range 800-900 DEG C, temperature error 3 DEG C, temperature retention time 10-80 hour.Room temperature is progressively cooled to again after insulation terminates.Dock the external pressure that the powder in head tube can continue in heat treatment process, also can not apply external pressure.Finally make Nb 3al superconducting joint.Fig. 1 is Nb 3al superconducting joint preparation flow block diagram.Wherein, the block diagram content of dotted line is the Standard processing protocol (part) of superconducting line factory, and the block diagram content of solid line is content flow of the present invention.
Adopt the Nb that the soldering legal system of prior art is standby 3al superconducting joint, Nb and Nb that its joint design is wrapped up by SnPbBi solder 3the Nb of Al 3al superconducting line and Nb 3the formations such as Sn layer.Current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb 3nb in Al superconducting line 3al core → Nb 3nb matrix → the Nb of Al superconducting line 3the Nb on Al superconducting line surface 3sn layer → SnPbBi solder → Nb 3the Nb on Al superconducting line surface 3sn layer → Nb 3nb matrix → the Nb of Al superconducting line 3nb in Al superconducting line 3al core; Current spread direction along wire termination is: Nb 3nb in Al superconducting line 3al core → SnPbBi solder → Nb 3nb in Al superconducting line 3al core, as shown in Figure 2.
Adopt Nb of the present invention 3al superconducting joint, the composition before diffusion heat treatments is from the inside to the outside: the Nb comprising Nb matrix and Nb-Al supersaturated solid solution 3al superconducting line presoma, Nb-Al supersaturated solid solution powder and the junction block be made up of Ta layer and Cu layer, as shown in Figure 3.Adopt Nb prepared by the inventive method 3the composition of Al superconducting joint after diffusion heat treatments is from the inside to the outside: comprise Nb matrix and Nb 3the Nb of Al core 3al superconducting line, Nb 3al sintered body and the junction block be made up of Ta layer and Cu layer, as shown in Figure 4.
Superconducting joint of the present invention and preparation method will generate the Nb of superconduction after Nb-Al supersaturated solid solution sintering alloy powder 3al sintered body, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb 3nb in Al superconducting line 3al core → Nb 3nb matrix → the Nb of Al superconducting line 3al sinters block → Nb 3nb matrix → the Nb of Al superconducting line 3nb in Al superconducting line 3al core; Current spread direction along wire termination is: Nb 3nb in Al superconducting line 3al core → Nb 3al sinters block → Nb 3nb in Al superconducting line 3al core, as shown in Figure 5.Nb is used in current path in the present invention 3al sinters block and instead of Nb of the prior art 3sn layer and SnPbBi solder, obvious Nb 3the superconduction critical electric current of Al material and critical back surface field are all than Nb 3sn and SnPbBi material is high, with Nb to be connected 3the critical performance of Al superconducting line is basically identical, improves joint current carrying capacity and critical back surface field.Further, the Nb adopting sintering process to prepare 3al sintered material is the transformation method Nb that quenches with rapid heating and cooling 3the heat treatment process of Al superconducting line completes simultaneously, Nb 3al sintered material and Nb 3al superconducting line surface will produce metallurgical binding in heat treatment process, greatly reduce connection resistance.Also show in Figure 5, Nb of the present invention 3junction block one end closure in Al superconducting joint, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu; Nb 3the end of Al superconducting line is inclined-plane, Nb to be connected 3al superconducting line tries one's best, and the inclined-plane of these ends is face-to-face placement, or approximate placement face-to-face.
Embodiment one:
Preparation Nb 3al superconducting joint.First pure Nb powder and pure Al powder are mixed according to the atomic quantity proportioning of 3:1, powder diameter is 20 microns, and mixed powder quality amounts to 200 grams; The agate material ball grinder that pure Nb powder, pure Al powder and 5 grams, odium stearate powder and agate material abrading-ball 3000 grams together put into planetary ball mill is carried out high-energy ball milling.Process During High Energy Ball Milling carries out in vacuum environment, and vacuum degree is less than or equal to 1 × 10 -2pa.Fig. 6 is for prepare high-energy ball milling Nb by planetary type ball-milling mode 3the principle schematic of Al supersaturated solid solution powder.After ball milling, ball grinder is put into vacuum glove box, take out the Nb-Al over-saturation solid solution powder after ball milling under vacuum conditions, stored dry after Vacuum Package.Removing Nb 3the sheathing material of Al superconducting line presoma.In vacuum glove box, get the Nb of Nb-Al over-saturation solid solution powder and over-saturation solid solution state to be connected 3the end of Al superconducting line presoma is together packed in junction block, and to the pre-compacted that powder carries out, pressure is 5MPa; Junction block is the tubing string shape of an end closure, and tube wall is double-decker, and internal layer material is pure Ta, and skin is pure Cu; By Nb 3the coil of Al superconducting line presoma coiling and junction block entirety are put into vacuum heat treatment furnace fast and are carried out vacuum heat, vacuum degree 1 × 10 -2pa, be first heated to 180 DEG C of insulations 2 hours, then be warmed up to heat treatment temperature point 800 DEG C, temperature error 3 DEG C, temperature retention time 80 hours, docks the external pressure that the powder in head tube continues in heat treatment process; After heat treatment, control heat-treatment furnace temperature, progressively cool to room temperature with the cooling rate of 25 DEG C/h, then open heat-treatment furnace; Prepare Nb 3al superconducting coil and Nb 3al superconducting joint.Whole Nb 3al superconducting joint preparation process is carried out in vacuum environment, and vacuum degree is less than or equal to 1 × 10 -2pa.
Superconducting joint in the present embodiment is column construction, and it is respectively from the inside to the outside: Nb to be connected 3al superconducting line, be wrapped in Nb 3the Nb of Al superconducting line exterior circumferential 3al sinters block, most external holds Nb 3al superconducting line and Nb 3al sinters the junction block of block; Junction block one end closure, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu.Nb 3it is whole block material that Al sinters block, and Nb 3al sinters block and Nb to be connected 3the interface cleaning of Al superconducting line end is pollution-free, and bonding state is metallurgical binding.The purity 99.99% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.999% of the outer Cu of tube wall of junction block, thickness 1mm.The length 40mm of junction block, the Nb in junction block 3al sinters block and Nb to be connected 3the connecting length 30mm of Al superconducting line.Nb 3the end of Al superconducting line is inclined-plane.
Embodiment two:
Preparation Nb 3al superconducting joint.First Nb-20at%Al alloy powder and pure Al powder are mixed, make the atomic quantity proportioning of Nb and Al in two kinds of powder reach 3:1.The particle diameter of two kinds of powder is 200 microns, and quality amounts to 200 grams; Nb-20at%Al alloy powder and pure Al powder, the agate material ball grinder of putting into stirring ball mill together with 5 grams, dispersant odium stearate powder and agate material abrading-ball 3000 grams are carried out high-energy ball milling.Fig. 7 is for prepare high-energy ball milling Nb by stirring-type ball milling method 3the principle schematic of Al supersaturated solid solution powder.After ball milling, ball grinder is put into vacuum glove box, take out the Nb-Al over-saturation solid solution powder after ball milling, stored dry after Vacuum Package.Removing Nb 3the sheathing material of Al superconducting line presoma.In vacuum glove box, get the Nb of Nb-Al over-saturation solid solution powder and over-saturation solid solution state to be connected 3the end of Al superconducting line presoma is together packed in junction block, and to the pre-compacted that powder carries out, pressure is 20MPa; Junction block is the tubing string shape of an end closure, and tube wall is double-decker, and internal layer material is pure Ta, and skin is pure Cu; By Nb 3the coil of Al superconducting line presoma coiling and junction block entirety are put into vacuum heat treatment furnace fast and are carried out vacuum heat, vacuum degree 2 × 10 -3pa.First be heated to 180 DEG C of insulations 2 hours, then be warming up to 900 DEG C, temperature error 3 DEG C, temperature retention time 10 hours, the powder docked in heat treatment process in head tube does not give external pressure; After heat treatment, after slow cooling to room temperature, open heat-treatment furnace; Prepare Nb 3al superconducting coil and Nb 3al superconducting joint.
Superconducting joint in the present embodiment is column construction, and it is respectively from the inside to the outside: Nb to be connected 3al superconducting line, be wrapped in Nb 3the Nb of Al superconducting line exterior circumferential 3al sinters block, most external holds Nb 3al superconducting line and Nb 3al sinters the junction block of block; Junction block one end closure, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu.Nb 3it is whole block material that Al sinters block, and Nb 3al sinters block and Nb to be connected 3the interface cleaning of Al superconducting line end is pollution-free, and bonding state is metallurgical binding.The purity 99.995% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.9995% of the outer Cu of tube wall of junction block, thickness 1mm.The length 50mm of junction block, the Nb in junction block 3al sinters block and Nb to be connected 3the connecting length 40mm of Al superconducting line.Nb 3the end of Al superconducting line is inclined-plane.
Embodiment three:
Preparation Nb 3al superconducting joint.First pure Nb powder and pure Al powder are mixed according to the atomic quantity proportioning of 3:1, powder diameter is 100 microns, and quality amounts to 200 grams; The corundum material ball grinder that pure Nb powder, pure Al powder and 5 grams, dispersant odium stearate powder and corundum material abrading-ball 3000 grams together put into oscillatory type ball mill is carried out high-energy ball milling.Fig. 8 is for prepare high-energy ball milling Nb by oscillatory type ball milling method 3the principle schematic of Al supersaturated solid solution powder.After ball milling, ball grinder is put into vacuum glove box, take out the Nb-Al over-saturation solid solution powder after ball milling, stored dry after Vacuum Package.Removing Nb 3the sheathing material of Al superconducting line presoma.In vacuum glove box, get the Nb of Nb-Al over-saturation solid solution powder and over-saturation solid solution state to be connected 3the end of Al superconducting line presoma is together packed in junction block, and to the pre-compacted that powder carries out, pressure is 10MPa; Junction block is the tubing string shape of an end closure, and tube wall is double-decker, and internal layer material is pure Ta, and skin is pure Cu; By Nb 3the coil of Al superconducting line presoma coiling and junction block entirety are put into heat-treatment furnace fast and are heat-treated, and heat-treating atmosphere is flowing argon gas.First be heated to 180 DEG C of insulations 2 hours, then be warming up to 850 DEG C, temperature error 3 DEG C, temperature retention time 50 hours, the powder docked in heat treatment process in head tube does not give external pressure; After heat treatment, after slow cooling to room temperature, open heat-treatment furnace; Prepare Nb 3al superconducting coil and Nb 3al superconducting joint.
Superconducting joint in the present embodiment is column construction, and it is respectively from the inside to the outside: Nb to be connected 3al superconducting line, be wrapped in Nb 3the Nb of Al superconducting line exterior circumferential 3al sinters block, most external holds Nb 3al superconducting line and Nb 3al sinters the junction block of block; Junction block one end closure, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu.Nb 3it is whole block material that Al sinters block, and Nb 3al sinters block and Nb to be connected 3the interface cleaning of Al superconducting line end is pollution-free, and bonding state is metallurgical binding.The purity 99.99% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.999% of the outer Cu of tube wall of junction block, thickness 1mm.The length 40mm of junction block, the Nb in junction block 3al sinters block and Nb to be connected 3the connecting length 30mm of Al superconducting line.Nb 3the end of Al superconducting line is inclined-plane.

Claims (9)

1. a Nb 3al superconducting joint preparation method, it is characterized in that the step of described preparation method is: choose the material powder that particle diameter is 20-200 micron, the component of described material powder comprises pure Nb and pure Al, and the atomic quantity proportioning of Al and Nb in material powder is 3:1; Material powder is put into the grinding jar of agate or corundum ball material, put into the abrading-ball of material identical with grinding jar simultaneously, and put into odium stearate powder as dispersant, carry out high-energy ball milling and be prepared into Nb-Al over-saturation solid solution alloy powder; Removing Nb 3the sheathing material of Al superconducting line presoma, then by the Nb of described Nb-Al over-saturation solid solution alloy powder and over-saturation solid solution state to be connected 3the end of Al superconducting line presoma is packed in junction block together, and carries out pre-compacted to powder, and pressure range is 5-20MPa; Subsequently by junction block together with Nb 3al superconducting line presoma is together heat-treated, and system of heat treatment process is: be first heated to 180 DEG C of insulations 2 hours, then be warming up to 800-900 DEG C, insulation 10-80 hour, heat treatment temperature error 3 DEG C, controls heat-treatment furnace temperature subsequently and progressively cools to room temperature, make Nb after heat treatment completes 3al superconducting joint.
2. Nb according to claim 1 3al superconducting joint preparation method, is characterized in that in the component of described material powder, with Nb-Al alloy and the pure Nb of combination replacement of pure Al and the combination of pure Al.
3. Nb according to claim 1 3al superconducting joint preparation method, is characterized in that described high-energy ball milling is: planetary type ball-milling, stirring-type ball milling or oscillatory type ball milling.
4. Nb according to claim 1 3al superconducting joint preparation method, it is characterized in that described heat treatment atmosphere is vacuum, vacuum degree is less than or equal to 1 × 10 -2pa.
5. Nb according to claim 1 3al superconducting joint preparation method, is characterized in that described heat treatment atmosphere is slumpability gas.
6. Nb according to claim 5 3al superconducting joint preparation method, is characterized in that described slumpability gas is flowing argon gas.
7. Nb according to claim 1 3al superconducting joint preparation method, is characterized in that docking in described heat treatment process the external pressure that the powder in head tube continues.
8. Nb according to claim 1 3al superconducting joint preparation method, is characterized in that in described heat treatment process, the powder docked in head tube does not apply external pressure.
9. Nb according to claim 1 3al superconducting joint preparation method, is characterized in that whole Nb 3al superconducting joint preparation process needs to carry out in vacuum environment, and vacuum degree is less than or equal to 1 × 10 -2pa.
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