CN105925923A - Preparation method of high-strength and high-conductivity copper alloy serving as contact line material of high-speed rail with speed per hour of above 400 km - Google Patents

Abstract

The invention discloses a preparation method of a high-strength and high-conductivity copper alloy serving as a contact line material of a high-speed rail with speed per hour of above 400 km. Components of the alloy alloy accord with a form of CuXY, wherein X is at least one of Ag, Nb and Ta; and Y is at least one of Cr, Zr and Si. The method comprises the following steps: a simple substance and/or raw materials of an intermediate alloy are fed in a vacuum smelting furnace according to a designed alloy component ratio for heating, melting and casting in a mold to obtain an ingot; the ingot is drawn by multiple times at room temperature to deform as a bar or a line; the section shrinkage of a sample reaches above 80%; then, the bar or the line is annealed; the alloy is drawn again; in the phase, the section shrinkage of the sample is within 50%; then, the liquid nitrogen freeze treatment is performed for the obtained alloy, so that remained X or Y solid soluble atoms in a copper matrix are continuously separated out; and then, the copper alloy is obtained through slowly heating to reach the room temperature.

Description

Preparation method of high-strength and high-conductivity copper alloy used as contact wire material of high-speed railway above 400 kilometers per hour

technical field

The invention relates to a method for preparing a Cu alloy, in particular to a method for preparing a copper alloy used as a contact wire material for a high-speed railway, especially a high-speed railway with a speed of more than 400 kilometers per hour.

Background technique

Since 2009, my country's high-speed electrified railway (hereinafter referred to as high-speed rail) has achieved substantial leap-forward development. Beijing-Tianjin Line, Beijing-Shanghai Line and Beijing-Guangzhou Line have been opened successively, and the high-speed rail has a stable operating speed of 300 km/h. The development of high-speed electrified railways has created huge market demands and demanding performance requirements for its key components - contact wires. The materials used as contact wires are required to have the following characteristics at the same time: high strength, low linear density, good electrical conductivity, good abrasion resistance, good corrosion resistance, etc., especially strength and electrical conductivity are the core indicators.

At present, the conductor materials used in high-speed rail contact lines mainly include Cu-Mg, Cu-Sn, Cu-Ag, Cu-Sn-Ag, Cu-Ag-Zr, Cu-Cr-Zr and other series of Cu alloys, among which Cu-Cr-Zr It shows a more excellent comprehensive performance of strength and electrical conductivity. Patents CN200410060463.3 and CN200510124589.7 disclose the preparation of Cu-(0.02~0.4)%Zr-(0.04~0.16)%Ag and Cu-(0.2~0.72)%Cr-(0.07~0.15)%Ag alloys technology. Finished products are prepared through processes such as smelting, casting, thermal deformation, solid solution, cold deformation, aging and re-cold deformation. Patent CN03135758.X discloses Cu-(0.01~2.5)%Cr-(0.01~2.0)%Zr-(0.01~2.0)%(Y, The preparation method of La, Sm) alloy rods or sheets can obtain good electrical conductivity, thermal conductivity and softening resistance. Patent CN200610017523.2 discloses Cu-(0.05~0.40)%Cr-(0.05~0.2)%Zr-<0.20%(Ce+Y) alloy composition and its preparation technology, through smelting, forging, solid solution, deformation, aging Obtain high-strength and high-conductivity comprehensive performance as well as better heat resistance and wear resistance. Patent CN02148648.4 discloses Cu-(0.01~1.0)%Cr-(0.01~0.6)%Zr-(0.05~1.0)%Zn-(0.01~0.30)%(La+Ce) alloy composition and preparation technology, through Higher strength and electrical conductivity can be obtained through smelting, hot rolling, solid solution, cold rolling, aging, final rolling and other processes.

US Patent US6679955 discloses the preparation technology of Cu-(3~20)%Ag-(0.5~1.5)%Cr-(0.05~0.5)%Zr alloy obtained by rapid solidification and subjected to precipitation hardening by deformation heat treatment. US7172665 discloses the preparation technology of Cu-(2~6)%Ag-(0.5~0.9)%Cr alloy. The process includes uniform post-treatment, thermal deformation and solution treatment, and can add (0.05~0.2)% Zr. US6881281 provides a high-strength and high-conductivity Cu-(0.05~1.0)%Cr-(0.05~0.25)%Zr alloy with excellent fatigue and medium temperature properties. The concentration of S is guaranteed by strictly controlling the solution treatment parameters to ensure good performance.

With the continuous development of high-speed electrified railways, especially the National Thirteenth Five-Year Plan, it is clearly stated that a high-speed railway system with a speed of more than 400 kilometers per hour must be built in 2020, so that the performance of the matching contact wire material must also be improved to a strength > 680 MPa, electrical conductivity>78%IACS and annealing at 400°C for 2h strength decrease rate <10%. Such stringent performance standards make the currently used Cu-Mg, Cu-Sn, Cu-Ag, Cu-Sn-Ag, Cu-Ag-Zr, and Cu-Cr-Zr alloys cannot meet the minimum requirements for the performance of contact wire materials in high-speed railway systems with a speed of more than 400 kilometers per hour. New high-performance alloys must be developed to adapt to the continuous development of high-speed rail.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a high-strength and high-conductivity copper alloy, which can meet the requirements of contact wire materials for high-speed railway systems with a speed of more than 400 kilometers per hour.

The technical solution adopted by the present invention to realize the above-mentioned purpose of the invention is described in detail below.

The present invention provides a method for preparing a copper alloy, the composition of the copper alloy conforms to the form: CuXY, wherein X is selected from at least one of Ag, Nb and Ta, and Y is selected from at least one of Cr, Zr and Si ; In the copper alloy, the total content of X elements is greater than 0.01 and not higher than 20%, the total content of Y elements is greater than 0.01 and not higher than 2%, and the content of Cr is in the range of 0.01-1.5%, and the content of Zr is in the range of 0.01~0.5%, the content of Si is in the range of 0.01~0.3%; the method is as follows: put the elemental and/or intermediate alloy raw materials into the vacuum melting furnace according to the designed alloy composition ratio, heat up and melt, and cast them in the mold to obtain cast iron. Ingots, the ingots are drawn and deformed into long rods or wires at room temperature for multiple passes, so that the sample section shrinkage rate reaches more than 80%, and then the long rods or wires are annealed, and the annealing temperature is selected so that the X element The fiber composed of elements does not undergo spheroid fracture and can make Y elements form nano-precipitated phases, and the annealing time is selected in the range where fibers composed of X elements do not undergo spheroidized fractures and more than 50% of Y elements form nano-precipitated phases , and then the obtained alloy is drawn again. At this stage, the sample section shrinkage rate is within 50%, and then the obtained alloy is subjected to liquid nitrogen freezing treatment, so that the X or Y solid-solution atoms remaining in the copper matrix continue to precipitate, and then the temperature is slowly raised. to room temperature to obtain a copper alloy.

Further, the total content of element X in the copper alloy is preferably 3%-12%.

Further, the total content of Y element in the copper alloy is preferably 0.1%-1.5%.

Further, the copper alloy is one of the following: Cu-12%Ag-0.3%Cr-0.1%Zr-0.05%Si, Cu-12%Ag-12%Nb-1.3%Cr-0.4%Zr-0.3 %Si, Cu-0.1%Ag-0.1%Cr-0.1%Zr, Cu-12%Nb-1%Cr-0.4%Zr-0.1%Si, Cu-6%Ag-6%Ta-0.1%Cr, Cu -3%Ag-0.8%Cr-0.5%Zr-0.3%Si.

Further, the liquid nitrogen freezing treatment time is preferably 1 to 100 hours.

Further, after the alloy is subjected to liquid nitrogen freezing treatment, it is preferred to raise the temperature to room temperature at a rate of 2-10°C/min.

In the present invention, the preparation raw material can be simple substance and/or master alloy, and described master alloy can be Cu-(5%~50%)Nb, Cu-(3%~20%)Cr, Cu-(4%~ 15%) Zr, Cu-(5%~20%) Si, etc.

The prepared copper alloy of the present invention comprises the following features:

At room temperature, element X in the copper alloy exists in two forms of pure phase and solid solution atoms, wherein the content of element X in the form of solid solution atoms is less than 0.5%; element Y exists in the form of pure phase and solid solution atoms or CuY compounds and solid solution atoms. It exists in the form of dissolved atoms, and the content of Y element in the form of solid solution atoms is less than 0.1%;

The copper alloy exists in the form of long rods or wires, in which the X element in the pure phase form is embedded in the copper alloy in the form of fibers arranged in parallel, the fiber axis is roughly parallel to the copper alloy rod or wire axis, and the fiber The diameter is less than 100 nm, the length is greater than 1000 nm, the fiber spacing is less than 1000 nm, the phase interface between the fiber and the Cu matrix is a semi-coherent interface, and there are periodically arranged misfit dislocations distributed on the interface; those skilled in the art can understand that , the X fibers in the copper alloy cannot be absolutely "parallel" in the mathematical sense, and the fiber axis and the copper alloy rod or wire axis cannot be absolutely "parallel" in the mathematical sense, so here we use "Approximate" and "approximately" are more in line with the actual situation;

The Y element in pure phase or compound form in the copper alloy is embedded in the copper alloy in the form of particles, and more than 30% of the particles are distributed on the phase interface between the X fiber and the Cu matrix, and the diameter of the particles is less than 30 nm, and the spacing is less than 200 nm. , the phase interfaces between particles and Cu matrix and between particles and X fibers are semi-coherent interfaces or incoherent interfaces.

The copper alloy disclosed by the invention has a strength of over 690 MPa, an electrical conductivity of over 79% IACS, and an annealing rate of less than 10% after 2 hours of annealing at 400°C, which meets the requirements for contact wire materials of a high-speed railway system with a speed of over 400 kilometers per hour.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention uses liquid nitrogen low-temperature treatment to significantly reduce the solid solubility of alloying elements in the copper matrix, increase the precipitation tendency, promote the continued precipitation of residual solid solution atoms, and further purify the copper matrix to increase electrical conductivity.

2. The copper alloy prepared by the present invention has a unique structure. The high-density nanofibers formed by X elements can effectively hinder the movement of dislocations and produce a huge nanofiber strengthening effect, which improves the overall strength level of the alloy, so that the strength of the copper alloy can reach Above 690 MPa;

3. Use the axial direction of the fiber to be parallel to the axis of the alloy rod or wire to reduce the scattering of electron waves at the phase interface and ensure that the electrical conductivity of the alloy remains at a high level, reaching above 79% IACS;

4. Use nanoparticles to pin on the phase interface between the fiber and the copper matrix to prevent the spheroidization trend of the nanofibers during the annealing process and ensure that the alloy has a high resistance to softening temperature, so that the strength decrease rate of the alloy after annealing at 400 ° C for 2 hours is <10 %.

Description of drawings

Fig. 1 is the scanning electron micrograph of the copper alloy that embodiment 4 obtains;

Fig. 2 is a transmission electron micrograph of the semi-coherent interface between the Ag fiber and the Cu matrix in the alloy obtained in Example 1, and there are periodically misfit dislocations on the interface.

Fig. 3 is the scanning electron micrograph of Nb nanofiber in the alloy that embodiment 2 obtains;

4 is a transmission electron micrograph of Cr nanoparticles in the alloy obtained in Example 3.

detailed description

The technical scheme of the present invention will be further described below with specific examples, but protection scope of the present invention is not limited to this:

Example 1:

Using pure Cu, pure Ag, pure Cr, pure Zr and pure Si as raw materials, the vacuum melting furnace was used to heat up and melt and cast to obtain Cu-12%Ag-0.3%Cr-0.1%Zr-0.05%Si cast rods. Multi-pass drawing at room temperature makes the area shrinkage rate reach 80%. The obtained sample was annealed at 300 °C for 24 h, and then continued to be drawn at room temperature. At this stage, the area shrinkage rate was 50%. Finally, the sample was placed in liquid nitrogen for 24 h and then returned to room temperature at a rate of 10 °C/min to make the obtained alloy Contains a large number of fine Ag nanofibers and Cr, Zr, Si nanoparticles. The average diameter of nanofibers is 50 nm, the length is greater than 2000 nm, the distance between fibers is less than 1000 nm, and the interface between the fiber and the copper matrix is a semi-coherent interface, and there is a misfit dislocation for every 9 (111) atomic planes of Cu on the interface . The average diameter of Cr, Zr, and Si nanoparticles is 30 nm, and the spacing is less than 200 nm. The phase interface between Cr, Zr, and Si nanoparticles and Cu matrix is a semi-coherent interface, and the phase interface with X fibers is an incoherent interface.

Example 2:

Using pure Cu, Cu-20%Nb master alloy, Cu-5%Cr master alloy, pure Zr and pure Si as raw materials, using a vacuum melting furnace to heat up and melt and cast to obtain Cu-12%Nb-1%Cr-0.2%Zr- 0.1% Si cast rod, multi-pass drawing of the cast rod at room temperature to make the area shrinkage rate reach 85%. Afterwards, the sample was annealed at 320 °C for 16 h, and the obtained sample was drawn again. At this stage, the area shrinkage rate was 30%. Finally, the sample was placed in liquid nitrogen for 100 h, and then the temperature was raised at 5 °C/min to return to room temperature. The resulting alloy contains a large number of fine Nb nanofibers and Cr, Zr, Si nanoparticles. The average diameter of the nanofibers is 100 nm, the length is greater than 1000 nm, and the distance between the fibers is less than 8000 nm, and the interface between the fiber and the copper matrix is a semi-coherent interface, and a misfit dislocation appears every 13 (111) atomic planes of Cu on the interface . The average diameter of Cr, Zr, Si nanoparticles is 25nm, and the spacing is less than 150nm. The phase interface between Cr, Zr, Si nanoparticles and Cu matrix is semi-coherent interface, and the phase interface with X fiber is non-coherent interface.

Example 3:

Using pure Cu, pure Ag, Cu-15%Ta master alloy, and Cu-3%Cr master alloy as raw materials, the vacuum melting furnace is used to heat up and melt and cast to obtain Cu-6%Ag-6%Ta-0.1%Cr cast rods. The cast rod is drawn for multiple times at room temperature to make the area shrinkage rate reach 85%. Afterwards, the sample was annealed at 400°C for 8 hours, and the obtained sample was drawn again. At this stage, the area shrinkage rate was 40%. Finally, the sample was placed in liquid nitrogen for 1 hour, and then the temperature was raised at 2°C/min to return to room temperature, so that the obtained alloy Contains a large number of fine Ag and Ta nanofibers and Cr nanoparticles. The average diameter of the nanofibers is 100 nm, the length is greater than 1000 nm, the distance between the fibers is less than 1000 nm, and the interface between the fiber and the copper matrix is a semi-coherent interface, and there is a fault at every 9 Cu (111) atomic planes on the Cu/Ag interface. Coordination dislocation, a misfit dislocation appears every 10 Cu (111) atomic planes on the Cu/Ta interface. The average diameter of Cr nanoparticles is 20 nm, and the spacing is less than 100 nm. Cr nanoparticles are dispersed in copper grains and fiber interfaces, the phase interface between Cr nanoparticles and Cu matrix is a semi-coherent interface, and the phase interface with X fibers is an incoherent interface.

Example 4:

Using pure Cu, pure Ag, Cu-50%Nb master alloy, Cu-10%Cr master alloy, Cu-15%Zr master alloy and Cu-5%Si master alloy as raw materials, use vacuum melting furnace to heat up and melt and cast to obtain Cu -12%Ag-12%Nb-1.3%Cr-0.4%Zr-0.3%Si cast rod, multi-pass drawing of the cast rod at room temperature to make the area shrinkage rate reach 95%. Afterwards, the sample was annealed at 300°C for 8 hours, and the obtained sample was drawn again. At this stage, the area shrinkage rate was 30%. Finally, the sample was placed in liquid nitrogen for 200 hours and then heated at 10°C/min to return to room temperature, so that the obtained alloy Contains a large number of fine Ag and Nb nanofibers and Cr, Zr, Si nanoparticles. The average diameter of the nanofibers is 100 nm, the length is greater than 3000 nm, and the distance between the fibers is less than 800 nm, and the interface between the fiber and the copper matrix is a semi-coherent interface, and a dislocation appears every 9 Cu (111) atomic planes on the Cu/Ag interface. Coordination dislocation, a misfit dislocation appears on the Cu/Nb interface every 13 (111) atomic planes of Cu. The average diameter of Cr, Zr and Si nanoparticles is 25nm, and the spacing is less than 130nm. Cr, Zr, Si nanoparticles are dispersed in copper grains and fiber interfaces, the phase interface between Cr, Zr, Si nanoparticles and Cu matrix is semi-coherent interface, and the phase interface with X fiber is incoherent interface.

Example 5:

Using pure Cu, pure Ag, Cu-20%Cr master alloy, Cu-10%Zr master alloy and Cu-10%Si master alloy as raw materials, the vacuum melting furnace is used to heat up and melt and cast to obtain Cu-3%Ag-0.8%Cr -0.5%Zr-0.3%Si casting rod, the casting rod is drawn at room temperature for multiple times to make the area shrinkage rate reach 95%. After that, the sample was annealed at 250 °C for 128 h, and the obtained sample was drawn again. At this stage, the area shrinkage rate was 50%. Finally, the sample was placed in liquid nitrogen for 100 h, and then the temperature was raised at 8 °C/min to return to room temperature. The obtained alloy contains a large number of fine Ag nanofibers and Cr, Zr, Si nanoparticles. The average diameter of the nanofibers is 40 nm, the length is greater than 1500 nm, and the distance between the fibers is less than 2000 nm. The interface between the fiber and the copper matrix is a semi-coherent interface, and there is a dislocation on every 9 (111) atomic planes of Cu on the Cu/Ag interface. coordination dislocation. The average diameter of Cr, Zr and Si nanoparticles is 15nm, and the spacing is less than 90nm. Cr, Zr, Si nanoparticles are dispersed in copper grains and fiber interfaces, the phase interface between Cr, Zr, Si nanoparticles and Cu matrix is a semi-coherent interface, and the phase interface with X fiber is a semi-coherent interface.

The alloy that above-mentioned embodiment obtains adopts energy spectrum to test the content result of X and Y solid-solution atom in the copper matrix and sees Table 1, adopts scanning electron microscope and transmission electron microscope to combine energy spectrum technology to the alloy that above-mentioned embodiment obtains to measure fiber and The proportion of nanoparticles on the phase interface of the matrix to the overall nanoparticles, the results are shown in Table 1.

The content of copper matrix X and Y solid-solution atoms in the alloy of table 1 embodiment, and the proportion of nanoparticles on the phase interface between fiber and matrix

For the alloys obtained in the above examples, the standard tensile test was used to test the strength, the four-point method was used to test the room temperature conductivity, and the strength decrease rate was tested after annealing at 400°C for 2 hours. The obtained properties are shown in Table 2.

Table 2 Comparison of main properties of alloys

*The comparative alloy CuCrZrZnCoTiLa data comes from patent CN1417357A.

Claims (9)

1. the method preparing copper alloy, it is characterised in that: this copper alloy composition meets this form: CuXY, wherein at least one in Ag, Nb and Ta of X, at least one in Cr, Zr and Si of Y；In copper alloy, the total content of X element be more than 0.01 and not higher than 20%, the total content of Y element be more than 0.01 and not higher than 2%, and, the content range of Cr is 0.01 ~ 1.5%, and the content range of Zr is 0.01 ~ 0.5%, and the content range of Si is 0.01 ~ 0.3%；nullDescribed method is: according to the alloying component proportioning of design, simple substance and/or intermediate alloy raw material are loaded vacuum melting furnace，Heat up to melt and water and cast from acquisition ingot casting in mould，Ingot casting is at room temperature carried out multi pass drawing and is deformed into long bar or line，Sample in cross section shrinkage factor is made to reach more than 80%，Afterwards long bar or line are annealed，The temperature of annealing is chosen at the fiber making X element form and nodularization fracture does not occur and Y element can be made to form the scope of nanometer precipitated phase，The time of annealing is chosen at the fiber making X element form and nodularization fracture does not occur and makes the Y element more than 50% form the scope of nanometer precipitated phase，Afterwards gained alloy is carried out again drawing，This stage sample sectional shrinkage is within 50%，Afterwards gained alloy is carried out liquid nitrogen frozen process，X or the Y solid solution atom remaining in Copper substrate is made to continue to separate out，The most slowly it is warmed up to room temperature thus obtains copper alloy.

2. the method for claim 1, it is characterised in that: in copper alloy, the total content of X element is 3% ~ 12%.

3. the method for claim 1, it is characterised in that: in copper alloy, the total content of Y element is 0.1% ~ 1.5%.

4. method as claimed in claim 2, it is characterised in that: in copper alloy, the total content of Y element is 0.1% ~ 1.5%.

5. the method for claim 1, it is characterised in that described copper alloy is one of following: Cu-12%Ag-0.3%Cr-0.1%Zr-0.05%Si, Cu-12%Ag-12%Nb-1.3%Cr-0.4%Zr-0.3%Si, Cu-0.1%Ag-0.1%Cr-0.1%Zr, Cu-12%Nb-1%Cr-0.4%Zr-0.1%Si, Cu-6%Ag-6%Ta-0.1%Cr, Cu-3%Ag-0.8%Cr-0.5%Zr-0.3%Si.

6. the method as described in one of claim 1 ~ 5, it is characterised in that: the liquid nitrogen frozen process time is 1 ~ 100 hour.

7. the method as described in one of claim 1 ~ 5, it is characterised in that: after alloy is carried out liquid nitrogen frozen process, with the ramp of 2 ~ 10 DEG C/min to room temperature.

8. method as claimed in claim 6, it is characterised in that: after alloy is carried out liquid nitrogen frozen process, with the ramp of 2 ~ 10 DEG C/min to room temperature.

9. the method as described in one of claim 1 ~ 5, it is characterised in that obtained copper alloy includes following characteristics:

At ambient temperature, in this copper alloy, X element exists with pure phase and two kinds of forms of solid solution atom, is wherein less than 0.5% with the X element content of the form of solid solution atom；Y element is presented in pure phase and solid solution atom or CuY compound and solid solution atom, wherein with the content of the Y element of the form of solid solution atom less than 0.1%；

This copper alloy is presented in long bar or line, wherein, the X element of pure phase is embedded in inside copper alloy with the fibers form that less parallel arranges, fiber axially with Copper alloy bar or bobbin to almost parallel, and the diameter of fiber is more than 1000 nm less than 100 nm, length, fiber spacing is less than 1000 nm, fiber is semicoherent interface with the boundary of Cu matrix, and the misfit dislocation of periodic arrangement is distributed on interface；

In this copper alloy, the Y element of pure phase or compound form is embedded in inside copper alloy in granular form, and more than 30% distribution of particles on the boundary of X fiber and Cu matrix, the diameter of particle is less than 30 nm, being smaller than 200 nm, particle is semicoherent interface or incoherent interface with the boundary of Cu matrix and particle and X fiber.