CN1312301C

CN1312301C - Prepn process of high temperature superconductive Ni-W alloy

Info

Publication number: CN1312301C
Application number: CNB2005101048282A
Authority: CN
Inventors: 刘丹敏; 张久兴; 郝斐; 胡延槽; 高菲; 周美玲
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2005-09-23
Filing date: 2005-09-23
Publication date: 2007-04-25
Anticipated expiration: 2025-09-23
Also published as: CN1740357A

Abstract

The present invention belongs to the field of coating a tough base band with high temperature superconductivity and the preparation of a superconductive film thereof. The smelting easily causes the non-uniform distribution of W, and the casting easily forms holes with low-density; thus, the density needs to be improved by subsequent hot forging which causes the oxidization of the surface of materials. Powder metallurgy has the defects of long cycle, high temperature, coarse and large crystal grains and low-density. The present invention comprises the following steps: Ni powder and W powder are uniformly mixed, wherein the purity is more than 99.9%, the granularity is from 3 to 6 micrometers, and the atomic percent of W of the alloy components is from 3 to 7%; the mixed powder is filled in a mould and is treated by spark plasma sintering at a temperature of 800 to 1200 DEG C and a pressure of 30 to 80MPa, and is treated by heat preservation for 0 to 10 minutes; a Ni-W plate is treated by cold rolling at a room temperature, wherein the deflection per pass is from 5 to 15%, and the total deflection is more than 97%; Ar is mixed with H2 atmosphere, and treated with recrystallization anneal, wherein H2 accounts for 4 vol%, the temperature is from 900 to 1300 DEG C, and the anneal is carried out for 0.5 to 3 hours. The present invention has the advantage of simple and rapid production process, and can prepare alloy blocks with uniform components and fine crystal particles, and a crystal Ni-W base band containing strong recrystallization texture with an individual component {100}; thus, the present invention can be used for depositing a YBCO high-temperature superconductive film.

Description

The preparation method who is used for the Ni-W alloy of high-temperature superconductor

Technical field

The present invention relates to a kind of polycrystal Ni-W base band preparation method, belong to the technical field of high-temperature superconducting coating tenacity strip and superconducting thin film preparation.

Background technology

With Bi is that superconducting tape is compared, YBa ₂Cu ₃O _7-δ(YBCO) superconductor possesses the ability of the bigger electric current of carrying in magnetic field, and application prospect is boundless.It is the important step that realizes its practical application that the fragility high temperature superconducting materia is made line, band.In recent years, the deposition superconducting film had been obtained very big progress with the research of preparation line, band on the employing polycrystalline tough metal base band, had successfully prepared high performance YBCO coating conductor.But the TEXTURE STATE of base band directly has influence on the TEXTURE STATE of epitaxially grown superconducting film thereon, and influences the electrical property of superconduction, so TEXTURE STATE is extremely important to the base band material.

Pure nickel is a kind of base band material that is widely used.This is because pure nickel has good working performance, drastic deformation and annealing back be very easy to form strong cubic texture 100}＜100〉(be most nickel crystallites with the 100} face is parallel to the face that rolls of base band, again with＜100〉direction is parallel to the rolling direction of base band).But the intensity of pure nickel is not high, and mechanical property is relatively poor; Be ferromegnetism (Curie temperature is 627K) under the normal temperature, make the application of YBCO coating conductor in the upfield meet difficulty (such as Magnetic resonance imaging etc.); And because the effect of magnetic hysteresis loss, the pure nickel base band can cause energy waste in AC applications.

The alloying of nickel is to solve the not high and ferromagnetic effective way of removal of pure nickel intensity, and wherein nickel tungsten has obtained paying close attention to widely.The Ni-W alloy base band possesses four advantages: strong cubic texture occurs after (1) violent cold rolling and recrystallization annealing; (2) strength of materials improves, and mechanical property is better; (3) with other Ni alloy phase ratios better oxidation-resistance is arranged, such as Ni-Cr, Ni-V, Ni-Fe; (4) magnetic is very little.Therefore, the Ni-W base band be easier to commercially produce can be in liquid nitrogen temperature (77K) and magnetic field the HTS YBCO band of bearing great current.

But because the fusing point of W is up to 3410 ℃, and atomic radius is big, has bigger difficulty with the alloying of Ni, thereby causes the uneven distribution of W influence the performance of base band and the intensity and the concentration degree of reduction biaxial texture easily in alloy material.Conventional art adopts the method or the metallurgy sintered method of ordinary powder of melting to prepare the Ni-W alloy block.Adopt the method for melting at first will prepare the Ni-W master alloy, carry out proportioning according to required alloying constituent then, melting and casting obtain alloy billet then.But be about 2000 ℃ because the fusing point of W and Ni differs, and the atomic radius of W is big, in alloy material, causes the uneven distribution of W easily, thereby influence the performance of base band, and reduce the intensity and the concentration degree of biaxial texture; And the easy cavity that forms of casting, density is low, and the homogeneity and the texture that influence base band distribute, thereby need follow-up forge hot to improve density, but the forge hot meeting causes the oxidation of material surface.And common powder metallurgy process preparation cycle is long, the sintering temperature height, and crystal grain is thick behind the sintering, and is difficult for the density that reaches high.

Discharge plasma sintering technique (Spark Plasma Sintering, be called for short SPS) be a kind of fast, the material preparation New Machining Technology of low temperature, energy-saving and environmental protection.This technology is directly to feed pulsed electrical energy between the pressurization powder particle, and the plasma body that is produced by spark discharge moment heats, and utilizes heat effect, field-effect etc. to carry out short period of time agglomerating new technology at low temperature.The electric energy of its consumption has only 1/5～1/3 of conventional sintering technology (pressureless sintering PLS, hot pressed sintering HP, hot isostatic pressing HIP).The SPS technology has hot pressing, the incomparable advantage of hot isostatic pressing technique:

In the agglomerating starting stage, because the effect of pulsed current, between powder particle, produce electric discharge phenomena, the gentle discharge impact of particle height such as produce press, not only can effectively remove the adsorbed gas and the impurity of powder particle surface, and because the rapid diffusion that discharge causes has promoted the particle densification process.Therefore SPS can obtain the material of homogeneous, densification.Up to now, do not see that discharge plasma sintering method prepares the Ni-W alloy material.

Summary of the invention

The present invention obtains the Ni-W alloy block that composition is even, crystal grain is tiny for adopting discharge plasma sintering method (SPS) preparation Ni-W alloy material both at home and abroad first, makes preparation process simplification and rapid simultaneously.

After this by controlling the deformation and the recrystallization annealing process of Ni-W alloy, obtain certain modulated structure comprising controlled rolling total deformation and every time deflection, adopt certain recrystallization annealing temperature, annealing atmosphere and annealing time then, obtained having very strong one-component 100}＜100〉and the polycrystalline Ni-W base band of recrystallization texture, can be used to deposit the YBCO high temperature superconducting film.

The invention provides a kind of preparation method who is used for the Ni-W alloy of high-temperature superconductor, it is characterized in that, may further comprise the steps:

(1) employed starting material are Ni powder and W powder, and purity is weight percentage more than 99.9%, and granularity is 3～6 microns, and the atomic percent of alloying constituent W is 3～7%; Nickel powder and tungsten powder are mixed, be encased in then and carry out discharge plasma sintering in the mould; Sintering temperature is 800 ℃～1200 ℃, and the sintered heat insulating time is 0～10 minute; Sintering pressure is 30-80Mpa;

(2) at room temperature the Ni-W plate is carried out cold rollingly, pass deformation is 5～15%, total deformation be 97% and more than;

(3) adopt Ar mixing H ₂Atmosphere is carried out recrystallization annealing, wherein H ₂Volume percent be 4%, 900～1300 ℃ of annealing temperatures, annealing time is 0.5～3 hour.

Above-mentioned steps (2) pass deformation forms twin too greatly easily in the Ni-W band, be unfavorable for the acquisition of single-orientated texture; Through our research, pass deformation is 5～15% suitable; Total deformation is less than 97%, and texture is concentrated inadequately.

The present invention obtains the Ni-W alloy block that composition is even, crystal grain is tiny, makes preparation process simplification and rapid simultaneously.The present invention obtained having very strong one-component 100}＜100〉the polycrystalline Ni-W base band of recrystallization texture, can be used to deposit the YBCO high temperature superconducting film.

Description of drawings:

The EBSD figure of Ni-3%W base among Fig. 1: the embodiment 1;

The crystal grain distributed data figure of Ni-3%W base among Fig. 2: the embodiment 1;

(111) of Ni-3%W strip and (200) utmost point figure among Fig. 3: the embodiment 1;

The EBSD figure of Ni-5%W base among Fig. 4: the embodiment 2;

The crystal grain distributed data figure of Ni-5%W base among Fig. 5: the embodiment 2;

(111) of Ni-5%W strip and (200) utmost point figure among Fig. 6: the embodiment 2;

The ω rocking curve figure (left side) of (111) crystal face PHI scintigram (right side) of Ni-5%W strip and (200) crystal face among Fig. 7: the embodiment 2.

The EBSD figure of Ni-7%W base among Fig. 8: the embodiment 3;

The crystal grain distributed data figure of Ni-7%W base among Fig. 9: the embodiment 3;

(111) of Ni-7%W strip and (200) utmost point figure among Figure 10: the embodiment 3.

Embodiment

Below in conjunction with drawings and Examples the present invention is described in further details.

It is starting material that example 1. adopts Ni powder and W powder, and purity is weight percentage 99.9%, and Ni powder degree is 4～6 microns, and W powder degree is 3～4 microns, and W accounts for that the composition atomic percent is 3% in the alloy.The mould of packing into after mixing carries out the SPS sintering.Sintering temperature is 800 ℃, and the sintered heat insulating time is 10 minutes.Sintering pressure is 80MPa.Obtained density and be 98% Ni-3%W piece.Fig. 1 is its EBSD (EBSD) figure, and grain size is comparatively even as seen from the figure.The crystal grain distributed data of Fig. 2 for calculating by EBSD result, the average crystal grain size of data presentation sample is about 10 microns, crystal grain is tiny.The power spectrum test result shows, W distributing very evenly in alloy.

At room temperature the Ni-3%W piece is carried out cold rolling and recrystallization annealing, cold rolling pass deformation is 5～10%, and total deformation is 97%; Adopt Ar mixing H2 (volume percent of H2 is 4%) atmosphere to carry out recrystallization annealing, 900 ℃ of annealing temperatures, annealing time is 0.5 hour.Obtained having very strong, single-orientated 100}＜100〉strip of texture, Fig. 3 is its (111) and (200) utmost point figure.Obtain extraordinary cubic texture Ni-3%W base band material, can be used for the preparation of follow-up YBCO coating superconducting material.

It is starting material that example 2. adopts Ni powder and W powder, and purity is weight percentage 99.99%, and Ni powder degree is 3～5 microns, and W powder degree is 3～5 microns, and W accounts for that the composition atomic percent is 5% in the alloy.The mould of packing into after mixing carries out the SPS sintering.Sintering temperature is 1000 ℃, and the sintered heat insulating time is 5 minutes.Sintering pressure is 50MPa.Obtained density and be 98.5% Ni-5%W piece.Fig. 4 is its EBSD (EBSD) figure, homogeneous grain size as seen from the figure.The crystal grain distributed data of Fig. 5 for calculating by EBSD result, the average crystal grain size of data presentation sample is about 10 microns, crystal grain is tiny.The power spectrum test result shows, W distributing very evenly in alloy.

At room temperature the Ni-5%W piece is carried out cold rolling and recrystallization annealing, cold rolling pass deformation is 10～15%, and total deformation is 98%; Adopt Ar mixing H ₂(H ₂Volume percent be 4%) atmosphere carries out recrystallization annealing, 1100 ℃ of annealing temperatures, annealing time is 2 hours.Obtained having very strong, single-orientated 100}＜100〉strip of texture, Fig. 6 is its (111) and (200) utmost point figure.Fig. 7 is PHI scintigram (right side) of its (111) crystal face and the ω rocking curve figure (left side) of (200) crystal face.The halfwidth of the ω rocking curve of the halfwidth (HWFM) of (111) crystal face PHI scanning and (200) crystal face has only 7.01 ° and 4.73 ° (HWFM) respectively as seen from the figure, really be to have obtained extraordinary cubic texture Ni-5%W base band material, can be used for the preparation of follow-up YBCO coating superconducting material.

It is starting material that example 3. adopts Ni powder and W powder, and purity is weight percentage 99.9%, and Ni powder degree is 4～6 microns, and W powder degree is 3～4 microns, and W accounts for that the composition atomic percent is 7% in the alloy.The mould of packing into after mixing carries out the SPS sintering.Sintering temperature is 1200 ℃, does not carry out sintered heat insulating.Sintering pressure is 30MPa.Obtained density and be 97.7% Ni-7%W piece.Fig. 8 is its EBSD (EBSD) figure, homogeneous grain size as seen from the figure.The crystal grain distributed data of Fig. 9 for calculating by EBSD result, the average crystal grain size of data presentation sample is about 6.6 microns, crystal grain is tiny.The power spectrum test result shows, W distributing very evenly in alloy.

At room temperature the Ni-7%W piece is carried out cold rolling and recrystallization annealing, cold rolling pass deformation is 5～10%, and total deformation is 97%; Adopt Ar mixing H ₂(H ₂Volume percent be 4%) atmosphere carries out recrystallization annealing, 1300 ℃ of annealing temperatures, annealing time is 3 hours.Obtained having certain intensity 100}＜100〉strip of texture, Figure 10 is its (111) and (200) utmost point figure.

Claims

1, a kind of preparation method who is used for the Ni-W alloy of high-temperature superconductor is characterized in that, may further comprise the steps:

1) employed starting material are Ni powder and W powder, and purity is weight percentage more than 99.9%, and granularity is 3～6 microns, and the atomic percent of alloying constituent W is 3～7%; Nickel powder and tungsten powder are mixed, be encased in then and carry out discharge plasma sintering in the mould; Sintering temperature is 800 ℃～1200 ℃, and the sintered heat insulating time is 0～10 minute; Sintering pressure is 30-80Mpa;

2) at room temperature the Ni-W plate is carried out cold rollingly, pass deformation is 5～15%, total deformation be 97% and more than;

3) adopt Ar mixing H ₂Atmosphere is carried out recrystallization annealing, wherein H ₂Volume percent be 4%, 900～1300 ℃ of annealing temperatures, annealing time is 0.5～3 hour.