RU2624564C2 - Manufacture method of biaxial textured support plate from triple alloy on copper-nickel basis - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the manufacture methods of biaxial textured support plates for epitaxial application on it the buffering and high-temperature superconducting layers for the band high temperature superconductors (HTSC) of the second generation. The manufacturing method of biaxially textured support plate on the copper-nickel basis includes the melting of the triple alloy, forging, cold reverse rolling upto the deformation degree of ≥ 97% and recrystallization annealing at the temperature of ≥ 1000°C, while iron, or vanadium, or chromium is introduced into the alloy on the copper-nickel basis as the alloying element with the following component ratio, at. %: iron ≤ 3 at. %, or vanadium ≤ 1.1 at. %, or chromium ≤ 3 at. %, nickel - 40-45 at. %, copper - the rest.

EFFECT: method allows to increase the strength of the textured support plate from the triple alloy on the copper-nickel basis, while maintaining the non-magnetization and the texturization degree.

1 ex, 1 dwg, 2 tbl

Description

The invention relates to metallurgy, in particular to methods for producing biaxially textured substrates.

The biaxially textured substrate serves as the basis for the epitaxial deposition of buffer and high-temperature superconducting (HTSC) layers on it. The finished multilayer tape can be used to transfer electricity with the least loss, create strong magnetic fields in helium-free HTSC solenoids, to design economical, with improved mass and size characteristics of products for the electric power industry and other sectors of the economy.

The problem of obtaining metal substrate tapes with a high degree of perfection of the cubic texture {100} <001> arose in the late 90s. in connection with the advent of technology for the production of second-generation high-temperature superconductors (HTSCs) based on the epitaxial deposition of ceramic HTSCs through buffer layers onto a textured metal substrate [Goyal A., Norton DP, Budai JD, Phavantham N., et. al. High Critical Current Density Superconductors Tapes by Epitaxial Deposition of YBa ₂ Cu ₃ O _x Thick Films on Biaxially Texturated Metals // Appl. Phys. Lett. 1996. V. 69, No. 16. P. 1795-1797].

The main characteristic of multilayer HTSC tapes is the critical current value, which is largely determined by the sharpness of the crystallographic texture in the superconductor material, inherited from the cubic texture of the metal substrate. In addition, the magnitude of the critical current is affected by the magnetic state of the substrate material. The lower the magnetic permeability of the substrate, the greater the critical current; therefore, it is desirable that the substrate material is non-magnetic at the operating temperature of the HTSC. For the production of long tapes in industry, it is also necessary to have sufficiently high strength properties of the supporting metal tape, which ensures the structural integrity of the HTSC layer.

The cubic texture after recrystallization annealing is obtained only in those metals and alloys with a face-centered cubic lattice (FCC) that have sufficiently high values of the stacking fault energy (EDU). The magnitude of the EMF determines the type of multicomponent deformation texture. The deformation textures of fcc metals contain three main components: S {123} <634>, C {112} <111> and B {110} <112> [Vishnyakov Y.D., Babareko AA, Vladimirov S.A. , Egiz I.V. Theory of texture formation in metals and alloys. M .: Science. 1979. 343 p.]. It is believed that in materials with low EDU, such as α-brass, only component (B) is developed. In materials with high EDF, such as A1 and Ni, components S and C prevail in the deformation texture. In materials with average EDF, for example, in Cu, all components C, S and B are present. In materials with a “type copper ”(materials with medium and high EDU) after primary recrystallization, a cubic texture {100} <001> is formed, and in materials with a deformation texture of“ brass type ”, i.e. with low EDU, a cubic texture does not form. When alloying a metal with a high and average value of the EDF, the EDF of the alloy decreases and after recrystallization annealing, the cubic texture will be formed only in those alloys in which there has not been a texture transition from the “copper type” deformation texture to the “brass type” deformation texture. This transition occurs when the sum of the volume fractions of the components C (112} <111> and S {123} <634> is approximately equal to the doubled volume fraction of the component B {110} <112> [Gervasyeva IV, Sokolov B.K., Rodionov D.P., Khlebnikova Yu.V. Texture formation in nickel alloys with some d - transition metals 1. Deformation texture // FMM 2003. T. 95. No. 1. P. 77-84; I. Gervasieva ., Sokolov B.K., Rodionov D.P., Khlebnikova Yu.V., Podkin Y.V. Texture formation in nickel alloys with some d-transition metals 2. Texture of recrystallization // FMM. 2003. T. 96 . No. 2. C. 95-101].

The substrate can be textured using deformation processes, such as deformation using rolling and recrystallization annealing of the substrate. An example of such a process is the process of biaxial texturing of a substrate using rolling (RABiTS process, from the English. "Rolling-assisted biaxially textured substrate"). In this case, large amounts of metal can be economically processed by cold rolling and recrystallization annealing, resulting in a high degree of texturing [US Patents No. 5739086, No. 5741377, No. 5898020].

A known method of manufacturing a biaxially textured substrate, including smelting, forging, cold rolling and subsequent recrystallization annealing, which uses various pure metals: Ni, Cu, Pd, Pt, Ag and some alloys of these metals [US Patent No. 6180570].

However, the listed pure metals have a very low yield strength in the textured state. In addition, the manufacture of a tape substrate on an industrial scale from biaxially textured palladium (or platinum) is impossible due to the high cost of the metal. In the described method of manufacturing the substrate, not all metals provide, after appropriate technological procedures, the formation of a sharp cubic texture and the required level of strength. For example, when silver is rolled at room temperature, a deformation texture of such a component composition is formed that it becomes impossible to obtain a cubic recrystallization texture upon subsequent annealing [Wasserman G., Greven I. Textures of metallic materials. M .: Metallurgy, 1969. 655 p.]. In pure copper, as well as in pure nickel, after high degrees of cold rolling, a texture of such component composition is formed that ensures the formation of a sharp cubic texture in the ribbon after primary recrystallization, but low strength properties do not allow the production of long ribbons.

A known method for the production of biaxially textured substrates, including smelting, forging, cold reverse rolling to a degree of deformation of more than 97% and recrystallization annealing at a temperature of ≥1000 ° C, which use various binary alloys based on nickel, the most preferred of which is a binary alloy based on Ni with 5 wt. % W [RF Patent No. 2,408956].

Such an alloy has a high degree of perfection of the crystallographic texture and the necessary strength, but nickel is a strong ferromagnet at 77 K, i.e. HTSC operating temperature, Ni alloy with 5 wt. % W is ferromagnetic. Since the magnitude of the critical current in the superconducting layer is affected by the magnetic state of the substrate material (the lower the magnetic permeability of the substrate, the greater the critical current), it is necessary that the substrate material be non-magnetic at the operating temperature of the HTSC. In addition, the use of refractory tungsten as an alloying element creates a number of technological difficulties at the stage of alloy smelting, in particular in the manufacture of alloys.

There is also known a method of manufacturing a biaxially textured substrate from a copper-nickel alloy, including smelting, forging, cold reverse rolling to a degree of deformation of more than 95% and recrystallization annealing at a temperature of ≥800 ° C, in which binary alloys are used as a copper-nickel alloy copper from 30 to 55 at. %, of which the preferred is non-magnetic at a temperature of 77 K binary alloy Ni-55 at. % Cu. [US Patent 5,964,966]. Such a copper-nickel alloy has three hardening (σ _0.2 ) in comparison with pure copper.

However, the desire to reduce the thickness of the metal substrate in order to reduce the weight of the structure of the HTSC wire dictates the need for a further increase in the strength of the tape. An increase in the strength of the copper-nickel alloy due to an increase in the nickel content in it is impossible, since the nickel content is 45-46 at. % is the limit for maintaining the paramagnetic state of the alloy (non-magnetic at a temperature of liquid nitrogen of 77 K). Therefore, it is not possible to achieve the required level of strength using double copper-nickel alloys.

Closest to the claimed technical essence is a method for manufacturing a biaxially textured triple alloy substrate on a copper-nickel basis - constantan, including smelting, forging, cold reverse rolling to a degree of deformation of more than 95% and recrystallization annealing at a temperature of ≥900 ° C [Varanasi CV , Brunke L., J Burke, Maartense I., Padmaja N., Efstathiadis H., Chaney A. and Barnes PN Biaxially textured constantan alloy (Cu 55 wt%, Ni 44 wt%, Mn 1 wt%) substrates for YBa ₂ Cu ₃ O _7-x coated conductors // Supercond. Sci. Technol. 2006. V. 19. P. 896-901.] This alloy is close in composition to the industrial constantan Cu-43% Ni-1.5% Mn (American standard C - 72150).

However, the introduction of such a third element as manganese into the copper-nickel base does not give advantages in terms of alloy hardening. Manganese present in industrial constantan is a technological additive in the deoxidation of liquid metal during smelting. When introduced into copper solid solution, manganese is 5-6 times less effective hardener per 1% alloying element than elements such as chromium and iron [Maltsev MV, Barsukova TA, Borin F.A . Metallography of non-ferrous metals and alloys. M .: GNTI for ferrous and non-ferrous metallurgy, 1960.372 s. (p. 15)]. Therefore, the manganese present in this ternary alloy on a copper-nickel basis does not allow reaching the required level of strength.

The basis of the invention is to increase the strength of a biaxially textured triple alloy substrate on a copper-nickel basis for epitaxial deposition of high-temperature superconducting layers, while maintaining the sharpness of the crystallographic texture and non-magnetism at the operating temperature of a high-temperature superconductor of 77 K.

The problem is solved in that in the method of manufacturing a biaxially textured triple alloy substrate on a copper-nickel basis for epitaxial deposition of high-temperature superconducting layers, including triple alloy smelting, forging, cold reverse rolling of the tape to a degree of deformation ≥97% and recrystallization annealing at a temperature ≥ 1000 ° C, according to the invention, when smelted into an alloy based on copper-nickel, iron or vanadium or chromium is introduced as an alloying element in the following ratio of components, at. %:

iron ≤ 3 at. %, or

vanadium ≤ 1.1 at. %, or

chrome ≤ 3 at. %

nickel - 40-45 at. %

copper is the rest.

To create triple copper-based alloys in which a sharp cubic texture can be obtained, it is advisable to use alloys with a nickel content of not more than 45 at. %, since they are non-magnetic at a temperature of liquid nitrogen of 77 K.

Alloying a copper-nickel solid solution with some 4-period transition elements, such as chromium, iron and vanadium, will significantly increase the strength properties of the rolled strip, since the hardening ability of these metals is higher than that of manganese contained in the known copper-nickel ternary alloy [Varanasi CV, Brunke L., J Burke, Maartense I., Padmaja N., Efstathiadis H., Chaney A. and Barnes PN Biaxially textured constantan alloy (Cu 55 wt%, Ni 44 wt%, Mn 1 wt%) substrates for YBa ₂ Cu ₃ O _7-x coated conductors // Supercond. Sci. Technol. 2006. V. 19. P. 896-901].

Alloying a copper-nickel alloy with any of the following elements: iron, vanadium, chromium, does not lead to a change in the type of deformation texture towards a decrease in the tendency to form a cubic recrystallization texture during annealing of the alloy. We have studied the process of changing the component composition of the texture of deformation and the formation of a cubic orientation after primary recrystallization in ternary alloys based on copper-nickel with the addition of chromium, iron or vanadium, as well as for comparison in pure copper, nickel and a double copper-nickel alloy.

For all ternary alloys, the sum of the main deformation components C and S is more than twice the amount of component B (Table 1), and after recrystallization annealing at a temperature of ≥1000 ° C, a sharp cubic texture with a volume fraction of grains with orientation {001) is formed in rolled strips of these alloys } <100> ± 10 ° more than 99% (Fig. 1).

Table 1 shows the volume fraction (± 10 °) of the main components of the deformation texture in samples of copper, nickel, Cu-40% Ni alloy and ternary copper-nickel based alloys,%.

Alloying copper with nickel does not lead to a decrease, but, on the contrary, to a certain increase in the ED of a pure metal [Gallagher P.C.J. The Influence of Alloying, Temperature, and Related Effects on the Stacking Fault Energy // Met. Trans. 1970. V. 1. P. 2429-2460], which, in turn, leads to a change in the type of deformation texture in the direction of increasing the tendency to form a cubic recrystallization texture during annealing of a double copper-nickel alloy. The complex alloying of copper with nickel and a 3 d-transition metal of 4 periods when creating a triple alloy on a copper-nickel basis allows one to achieve significant hardening of the tape, while maintaining the non-magnetism and tendency of double copper-nickel alloys to form a perfect cubic recrystallization texture. The addition of chromium, iron, or vanadium as a third element in a double copper-nickel alloy, which leads to four-fold hardening of the substrate tape (Table 2), makes it possible to reduce the thickness of the substrate tape and, consequently, the weight of the entire structure of the HTSC wire. We have established threshold values for the content of the alloying element (Cr, Fe or V) in ternary alloys based on copper-nickel, weight. %: 0.5≤Cr≤3; 0.5≤Fe≤3; 0.5≤V≤1.1. When the content of the Cu-Ni-Me (Me = Cr, Fe, V) ternary alloy on a copper-nickel base is less than 0.5 weight. % dopant will not achieve the required level of strength of the tape substrate. On the other hand, the amount of chromium is 3 weight. % in a copper-nickel-based ternary alloy corresponds to its extreme solubility in the fcc copper-nickel matrix and exceeding this value can lead to the appearance of particles of the second phase, which in turn can lead to degradation of the cubic texture. A similar situation is observed for the Cu – Ni – V alloy with the difference that the limiting solubility of vanadium in the copper – nickel fcc matrix is lower and amounts to ≤1.1 wt. % When creating a Cu-Ni-Fe ternary alloy, it is also necessary to take into account the fact that ferromagnetic iron additives increase the Curie temperature of the alloy and, when the iron content is more than 3%, the copper-nickel-based ternary alloy substrate will be magnetic at the working temperature of the superconductor.

The degree of perfection of the cubic texture of recrystallization of the ternary alloys Cu-Ni-Fe, Cu-Ni-Cr, Cu-Ni-V studied by us is presented in FIG. 1 and tab. 2.

Table 2 shows the chemical composition, mechanical properties, and parameters of the cubic texture of the investigated copper-nickel-based ternary alloys.

In FIG. 1. histograms of misorientation of grain boundaries and pole figures {001} are shown for ribbons from alloys Cu - 40% Ni - 1.4% Fe (a), Cu - 40% Ni - 1.2% Cr (b), Cu - 40% Ni - 1.1 % V (c) after recrystallization annealing of 1100 ° C, 1 h. The volume fraction of cubic grains with scattering of ± 10 ° is more than 99%.

The method is as follows.

Copper-nickel-based triple alloys are melted in alundum crucibles in an argon atmosphere in a vacuum induction furnace. Oxygen-free copper with a purity of 99.95%, nickel with a purity of 99.99%, carbonyl remelted iron with a purity of 99.94%, chromium and vanadium with a purity of at least 99.93% are used. The ingots are forged at a temperature in the range of 1000-800 ° C on bars with a cross section of 10 × 10 mm. After grinding, preforms of 9 × 9 × 150 mm are obtained, which are annealed at 550-600 ° C for 1.5 hours. The average grain size in the preforms should not exceed 40-50 microns. Cold rolling of billets is carried out in two stages: Stage 1 on a rolling mill with a roll diameter of 180 mm (deformation ~ 90%, number of passes 35-40); Stage 2 - on a two-roll rolling mill with polished rolls with a diameter of 55 mm to a tape with a thickness of 80-100 microns, the degree of cold deformation is 98-99%. Reverse rolling. Recrystallization annealing to obtain a biaxial texture is carried out for 1 hour in a vacuum oven (3⋅10 ^-5 mm Hg) at temperatures of 900, 950, 1000, 1050 or 1100 ° C. The heating of tape samples placed in a vacuum container is carried out by planting in a furnace heated to the required temperature, the samples are cooled after annealing outside the furnace space. After recrystallization annealing at a temperature of ≥1000 ° C, a sharp cubic texture with a volume fraction of grains with an orientation {001} <100> ± 10 ° of more than 99% is formed in the rolled strips from all alloys.

Example 1

Alloy: Ni - 40%, V - 1.1%, Cu - the rest, smelted in an argon atmosphere in a vacuum induction furnace. Oxygen-free copper with a purity of 99.95 weight is used. %, nickel with a purity of 99.99 weight. % and vanadium with a purity of not less than 99.93 weight. % An ingot weighing 500 g is forged at 1000-800 ° C per bar with a cross section of 10 × 10 mm. The resulting bar was subjected to grinding to a size of 9 × 9 × 150 mm. Then, the rod was annealed at a temperature of 600 ° C for 1.5 h to create a homogeneous fine-grained structure. The annealed rod was ground to a section of 6 × 6 mm. The initial grain size before cold rolling was 40 μm. Reverse rolling was carried out at room temperature. The degree of deformation was 98.6%, and the final thickness of the tape was ~ 85 μm. The sum of the volume fractions of the components of the strain texture was: S + C = 42.5%, 2B = 24.2% (Table 1). The sum of the volume fractions of the components S and C far exceeds the doubled volume fraction of component B, which indicates the realization of a sharp cubic texture in the ribbon after recrystallization annealing. As a result of recrystallization annealing in vacuum at a temperature of 1000 ° C for 1 h, an acute cubic texture with the content of orientation grains {001} <100> ± 10 ° ≥99% was formed in the alloy (see Fig. 1c).

Alloy: Ni - 40%, V - 1.1%, Cu - the rest, has high thermal stability to the development of secondary recrystallization. The yield strength of the finished tape is 100 MPa (see table. 2), which is almost 4 times higher than the yield strength of pure copper tape and 15 MPa higher than the yield strength of a ternary alloy on a copper-nickel basis with the addition of manganese (see table. 2 ) The alloy is non-magnetic at the operating temperatures of a high-temperature superconductor.

Claims (2)

A method of manufacturing a biaxially textured substrate of a copper-nickel-based alloy containing 40-45 at.% Nickel for epitaxial deposition of high-temperature superconducting layers, including alloy smelting with an alloying element introduced into the copper-nickel base, forging, cold rolling of the tape to the degree deformations of ≥97% and recrystallization annealing at a temperature of ≥1000 ° С, while the alloy is smelted on a copper-nickel basis with the introduction of iron, vanadium or chromium as an alloying element , With the following content at. %: iron ≤3, or vanadium ≤1.1, or chromium ≤3.

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