Preparation method of high-strength high-elasticity fatigue-resistant copper-niobium composite plate strip

Abstract

The application discloses a preparation method of high-strength high-elasticity fatigue-resistant copper-niobium composite plate strip, and relates to the technical field of copper-niobium composite plate strip, in particular to the preparation method of the copper-niobium composite plate strip. The method comprises the following steps: firstly, copper foil and niobium foil are wound into a shape and then placed in a copper alloy sheath for hot extrusion deformation, and then a copper-niobium composite wire is obtained through multi-pass cold drawing and intermediate annealing; secondly, the copper-niobium composite wire is gathered and arranged in the copper alloy sheath for hot extrusion deformation, and then a copper alloy / copper / niobium structure composite round wire is obtained through multi-pass cold drawing and twice intermediate annealing; and thirdly, the copper alloy / copper / niobium structure composite round wire is subjected to heat treatment and then multi-pass cold rolling deformation. The copper-niobium composite plate strip obtained through winding composite-extrusion-drawing, gathering composite-extrusion-drawing deformation and heat treatment-rolling deformation has a micron-scale copper alloy layer on the surface of the core wire, and an alternating nanometer-scale copper and niobium dual-phase sheet structure in the interior, so that the strength of the copper-niobium composite plate strip is improved, and the copper-niobium composite plate strip has high resilience, high conductivity, fatigue resistance, stress relaxation resistance, heat stability and high wear resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-strength and high-elasticity alloy, and particularly relates to a preparation method of high-strength and high-elasticity fatigue-resistant copper-niobium composite plate strip. BACKGROUND

[0002] Copper-based elastic alloy is widely used in medical treatment, aerospace and navigation instruments, mechanical manufacturing, electronic power and instrument manufacturing, and is mainly used for producing various current-carrying elastic elements, contact springs, switches, converters, terminal elements and the like, and is required to have high resilience, high mechanical strength, high electrical conductivity, excellent fatigue resistance and high-temperature thermal stability. At present, copper-based elastic alloy on the domestic market mainly uses beryllium bronze and tin phosphorus bronze materials. However, the beryllium powder used in the preparation process of beryllium bronze material is highly toxic, and at the same time, the beryllium bronze plate strip produced in the domestic market has a serious grain boundary segregation problem, poor thermal stability, poor high-temperature stress relaxation resistance, and is not suitable for long-term use at high temperature. The preparation process of tin phosphorus bronze is complex, the machinability is poor, the inverse segregation phenomenon is easy to form during casting, and the electrical conductivity is relatively low.

[0003] A large number of academic researches and customer feedbacks show that the current use of beryllium bronze and tin phosphorus bronze as the main material for manufacturing elastic electrical elements has the problem of significant performance deterioration with the increase of service time when used as a high-temperature stressed contact piece (such as the electrode of a contact welding machine). In order to improve the thermal stability and stress relaxation resistance of the elastic copper-based alloy, Cu-Ni-Sn alloy plates have been developed. However, the addition of multiple alloy elements greatly weakens the electrical conductivity of the Cu-Ni-Sn alloy plate when forming a saturated solid solution and during aging precipitation. Therefore, it is an important problem to be solved to design a new copper-based composite material structure and composition, propose a new processing and forming process, and develop a new copper-based composite plate, so that the prepared copper-based composite plate strip can simultaneously realize high strength, high electrical conductivity, high thermal stability, excellent fatigue resistance and high-temperature stress relaxation resistance. This is of great significance to replace the existing elastic copper-based alloy plate and solve the problem of poor high-temperature service performance. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a preparation method of high-strength high-elasticity fatigue-resistant copper-niobium composite plate strip to solve the problems of the prior art.

[0005] To solve the above technical problems, the present application adopts the technical scheme of a preparation method of high-strength high-elasticity fatigue-resistant copper-niobium composite plate strip, characterized in that the method comprises the following steps:

[0006] Step one, high-purity copper foil and high-purity niobium foil with a thickness of microns are alternately and layeringly wound according to a volume ratio of 1:1 by using a foil automatic winding device, and then placed in a copper alloy sheath to obtain a copper-niobium wound foil composite sheath. After vacuum seal welding of both ends of the copper-niobium wound foil composite sheath, hot extrusion deformation is performed to make the high-purity copper foil and the high-purity niobium foil interface solid-state welded, thereby obtaining a copper-niobium composite rod with a winding structure. Then, the copper-niobium composite rod with the winding structure is subjected to multi-pass cold drawing and intermediate annealing to obtain a copper-niobium composite wire with a hexagonal cross section.

[0007] Step two, the copper-niobium composite wire with the hexagonal cross section obtained in step one is used as a core wire and assembled in a copper alloy sheath to obtain a copper-niobium bundle composite sheath. After vacuum seal welding of both ends of the copper-niobium bundle composite sheath, hot extrusion deformation is performed to make the outer layer copper alloy of the inner core wire interface solid-state welded, and the outer sheath copper alloy and the outer layer copper alloy of the core wire interface solid-state welded. Thus, a copper-niobium bundle composite rod with a multi-core bundle structure is obtained. Then, the copper-niobium bundle composite rod with the multi-core bundle structure is subjected to multi-pass cold drawing, twice intermediate annealing, and multi-pass cold drawing to obtain a copper alloy / copper / niobium structure composite round wire with an outer layer copper alloy and an inner layer copper-niobium core wire.

[0008] Step three, the copper alloy / copper / niobium structure composite round wire obtained in step three is subjected to heat treatment and then multi-pass cold rolling deformation to obtain a high-strength high-elasticity fatigue-resistant, wear-resistant, and heat-stable copper-niobium composite plate strip. The tensile strength σb of the copper-niobium composite plate strip is greater than or equal to 1000 MPa, the yield strength / elastic modulus is greater than or equal to 0.008, and the cycle loading number N under a stress level of 30% is greater than or equal to 1.7×10 6Next, the softening temperature resistance is 600℃ or higher, and the electrical conductivity is 65% IACS or higher.

[0009] The present application obtains copper-niobium composite wire with hexagonal section by winding high-purity copper foil and high-purity niobium foil to form copper-niobium winding foil, putting it into copper alloy sheath, degassing, sealing, hot extrusion deformation, cold drawing deformation and intermediate annealing heat treatment, then bundles the copper-niobium composite wire as core wire into copper alloy sheath, degassing, sealing, hot extrusion deformation, cold drawing deformation and intermediate annealing heat treatment, obtains copper alloy / copper / niobium structure composite round wire, then carries out annealing heat treatment and cold rolling deformation to obtain copper-niobium composite plate strip. In the above preparation process, the present application finally obtains copper-niobium composite plate strip with nanometer scale copper and niobium dual-phase sheet structure alternately distributed by winding composite-extrusion-drawing, bundle composite-extrusion-drawing deformation, heat treatment-rolling deformation, nanometer scale copper-niobium core wire and high-density copper / niobium interface layer introduce a large number of gradient stress / strain and geometrically necessary dislocations at the copper / niobium interface, which greatly reduces the elastic modulus of the copper-niobium composite plate strip, the elastic modulus value is reduced by 40GPa-60GPa compared with the elastic modulus of copper alloy, improves the yield strength and tensile strength (>900MPa) of the copper-niobium composite plate strip, and realizes high resilience of the copper-niobium composite plate strip. At the same time, the bundle drawing of the present application makes the copper and niobium sheet structure into fiber layer with strong texture orientation, forms fiber structure similar to single crystal structure, ensures the copper-niobium composite plate strip to obtain high electrical conductivity (≥65% IACS), and the nanometer core wire structure and the fiber structure similar to single crystal and the high-density copper / niobium interface layer also greatly improve the fatigue resistance and stress relaxation resistance of the copper-niobium composite plate strip, so that it has good thermal stability (softening temperature resistance ≥600℃). In addition, the copper alloy sheath used in the primary assembly sheath and the secondary composite sheath has good wear resistance and stress relaxation resistance, and realizes high wear resistance of the copper-niobium composite plate strip.

[0010] The preparation method of the above-mentioned high-strength high-resilience fatigue-resistant copper-niobium composite plate strip is characterized in that the mass purity of the high-purity copper foil and the high-purity niobium foil in step one is 99.9%, and the thicknesses are the same, and the thicknesses are both in the range of 150μm-500μm, and the outer diameter of the copper alloy sheath is 80mm-120mm. The present application controls the thicknesses of the high-purity copper foil and the high-purity niobium foil, the outer diameter of the copper alloy sheath, adjusts the copper / niobium interface density, the copper and niobium core wire size, the mass proportion of copper, and then controls the internal gradient stress / strain level, dislocation movement and critical shear stress and electrical transport capacity, so that the prepared copper-niobium composite plate strip obtains the best matching of strength, electrical conductivity, high-temperature thermal stability and fatigue resistance.

[0011] The preparation method of the high-strength high-elasticity fatigue-resistant copper-niobium composite plate strip has the characteristics that in step one, the pass deformation rate of the multi-pass cold drawing is 10-15%, and the temperature of the intermediate annealing is 680-720 DEG C, and the time is 2.5-3 hours.

[0012] The preparation method of the high-strength high-elasticity fatigue-resistant copper-niobium composite plate strip has the characteristics that in step two, the copper alloy sheath is copper-nickel-silicon or copper-nickel-tin alloy, and the outer diameter is 80-150 mm, the temperature of the hot extrusion deformation is 700-750 DEG C, the pass deformation rate of the multi-pass cold drawing is 10-15%, and the intermediate annealing temperature is 680-720 DEG C, and the copper alloy / copper / niobium structure composite round wire is a structure of outer high-strength wear-resistant copper alloy and inner high-strength high-elasticity high-toughness high-thermal-stability and fatigue-resistant copper-niobium nanometer composite core wire.

[0013] The preparation method of the high-strength high-elasticity fatigue-resistant copper-niobium composite plate strip has the characteristics that in step three, the diameter of the copper alloy / copper / niobium structure composite round wire is phi 3.5-5.0 mm, the temperature of the heat treatment is 650-700 DEG C, the holding time is 2-3 hours, the pass deformation rate of the multi-pass cold rolling deformation is 25-40% when the cold rolling object is thicker than 1 mm, 15-20% when the cold rolling object is thicker than 0.5 mm but less than 1 mm, 5-15% when the cold rolling object is thicker than 0.3 mm but less than 0.5 mm, and 1-5% when the cold rolling object is less than 0.3 mm, and the thickness of the copper-niobium composite plate strip is 0.25-0.5 mm.

[0014] Compared with the prior art, the present application has the following advantages:

[0015] 1. The copper-niobium composite plate strip with the nanometer-scale copper-niobium dual-phase flake structure is obtained through the winding composite-extrusion-drawing, the cluster composite-extrusion-drawing deformation, and the heat treatment-rolling deformation process, the nanometer-scale copper-niobium core wire and the high-density copper / niobium interface layer introduce a large number of gradient stress / strain and geometrically necessary dislocations at the copper / niobium interface, which greatly reduces the elastic modulus of the copper-niobium composite plate strip, improves the yield strength and tensile strength of the copper-niobium composite plate strip, realizes the high resilience of the copper-niobium composite plate strip, and the cluster drawing large plastic deformation forms the fiber structure similar to the single crystal structure, so that the copper-niobium composite plate strip obtains higher conductivity, fatigue resistance, stress relaxation resistance and thermal stability, and the copper alloy sleeve realizes the high wear resistance of the copper-niobium composite plate strip.

[0016] 2. Compared with the preparation process of the elastic beryllium bronze alloy, the beryllium powder with high toxicity and flammability needs to be added, and the beryllium powder is easy to volatilize in the adding process, so that the preparation process needs to be strictly sealed and the operator needs to be strictly protected, thereby bringing production inconvenience and safety hazards. The material used in the preparation method of the present application includes high-purity copper foil, high-purity niobium foil, oxygen-free copper and copper alloy sleeve, which are non-toxic and have good stability, and are easy to obtain and store. The material and the preparation process are safe and convenient to operate.

[0017] 3. The winding composite-extrusion-drawing, cluster composite-extrusion-drawing deformation, heat treatment-rolling deformation and other large plastic deformation process of the present application is simple and easy to realize industrialized batch production. At the same time, by stacking and winding the high-purity copper foil and the high-purity niobium foil and assembling the copper-niobium composite wire into a cluster and then performing large plastic deformation, the uniformity of the internal organization of the copper-niobium composite plate strip is easy to realize, and the nanometer-scale core wire is obtained, which solves the problems of organization segregation, different reinforcing phase sizes and uneven composition existing in the preparation process of the current elastic copper-based alloy materials beryllium bronze, tin phosphorus bronze and copper-nickel-tin alloy by using the melting method and powder metallurgy method, and ensures the uniformity of the mechanical properties of the high-strength and high-elasticity copper-niobium composite plate strip.

[0018] The technical solutions of the present application will be further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The actual picture of the copper alloy / copper / niobium structure composite round wire prepared in examples 1-3 of the present application.

[0020] Figure 2 The actual picture of the copper-niobium composite plate strip prepared in examples 1-3 of the present application.

[0021] Figure 3 The electron backscattering pattern (EBSD) analysis result picture of the longitudinal section of the copper-niobium composite plate strip prepared in example 1 of the present application.

[0022] Figure 4 SEM image of copper niobium nanometer core filaments in copper niobium composite plate strip prepared in Example 1 of the present application.

[0023] Figure 5 TEM image of nanometer niobium core filaments in copper niobium composite plate strip prepared in Example 1 of the present application.

[0024] Figure 6 N-S curve diagram of bending fatigue test of copper niobium composite plate strip prepared in Example 1 of the present application.

[0025] Figure 7 Comparison diagram of resilience analysis of copper niobium composite plate strip prepared in Examples 1-3 of the present application and beryllium nickel copper alloy plate strip. DETAILED DESCRIPTION

[0026] Example 1

[0027] This example includes the following steps:

[0028] Step one, high purity copper foils and high purity niobium foils with mass purity of 99.9% and thickness of 150 μm are alternately and closely stacked together in layer distribution according to volume ratio of 1:1 by using foil automatic winding device, and then are wound into shape on the automatic winding equipment, and then are placed in copper alloy sheath with outer diameter of 80 mm and wall thickness of 8 mm to obtain copper niobium winding foil composite sheath, and then the copper niobium winding foil composite sheath is vacuum degassed and electron beam sealed at both ends, and then is subjected to hot extrusion deformation at 700 ℃ to make the high purity copper foil and high purity niobium foil interface solid state welding, and then a copper niobium composite rod with winding structure with diameter of Φ20 mm is obtained, and then the copper niobium composite rod with winding structure is subjected to multi-pass cold drawing with pass deformation rate of 10% and intermediate annealing at 720 ℃ for 3 h to obtain copper niobium composite wire with hexagonal cross section;

[0029] Step two, 853 copper niobium composite wires with hexagonal cross section obtained in step one are used as core filaments to be assembled in copper nickel silicon alloy sheath with outer diameter of 80 mm to obtain copper niobium bundle composite sheath, and then the copper niobium bundle composite sheath is vacuum sealed at both ends and then is subjected to hot extrusion deformation at 750 ℃ to make the outer layer copper alloy interface of the inner core filaments solid state welding, and the outer layer copper alloy interface of the outer sheath copper alloy and the core filaments solid state welding, and then a copper niobium bundle composite rod with multi-core bundle structure with diameter of 20 mm is obtained, and then the copper niobium bundle composite rod with multi-core bundle structure is subjected to multi-pass cold drawing with pass deformation rate of 15%, intermediate annealing at 720 ℃ for 2 times for 3 h, and multi-pass cold drawing with pass deformation rate of 15% to obtain copper alloy / copper / niobium structure composite round wire with structure of copper alloy / outer layer high strength wear-resistant copper alloy / inner layer high strength, high elasticity, high toughness, high thermal stability and fatigue resistance copper niobium nanometer composite core filaments with diameter of φ5.0 mm, as shown in Figure 1 ​

[0030] Step three, the copper alloy / copper / niobium structure composite round wire with a diameter of φ5.0 mm obtained in step three is heat treated at 700℃ for 2h, and then is subjected to multi-pass cold rolling deformation, the pass deformation rate of the multi-pass cold rolling deformation is 40% when the cold rolling object has a thickness of 1mm or more, is 20% when the cold rolling object has a thickness of 0.5mm or more and less than 1mm, is 15% when the cold rolling object has a thickness of 0.3mm or more and less than 0.5mm, and is 5% when the cold rolling object has a thickness less than 0.3mm, and the diameter size of the copper alloy / copper / niobium structure composite round wire changes to 5mm, 4.4mm, 3.71mm, 3.5mm, 2.98mm, 2.53mm, 2.21mm, 1.89mm, 1.61mm, 1.32mm, 1.07mm, 0.89mm, 0.71mm, 0.55mm, 0.5mm in sequence during the multi-pass cold rolling deformation, and finally a high-strength high-elasticity fatigue-resistant wear-resistant and heat-stable copper niobium composite strip with a thickness of 0.5mm is obtained, as shown in FIG. 1. Figure 2

[0031] The strength and elastic modulus of the copper niobium composite strip prepared in the embodiment and the beryllium nickel copper alloy strip (alloy element composition: Be 0.2% to 0.6%, Ni 1.4% to 2.2%, and the rest is Cu) with a C17510 brand in the prior art are detected, and the results are shown in Table 1.

[0032] Table 1

[0033]

[0034] As can be seen from Table 1, the yield strength σ0.2 and the tensile strength σb of the copper niobium composite strip prepared in the embodiment are higher than the yield strength σ0.2 and the tensile strength σb of the beryllium nickel copper alloy strip, wherein the tensile strength σb of the copper niobium composite strip is about 150MPa higher than that of the beryllium nickel copper alloy strip, and the yield strength σ0.2 of the copper niobium composite strip is about 15MPa higher than that of the beryllium nickel copper alloy strip at different temperatures (20℃ to 300℃); at the same time, the elastic modulus E0 of the copper niobium composite strip prepared in the embodiment is lower than that of the beryllium nickel copper alloy strip, and the elastic modulus is about 30GPa to 40GPa lower than that of the beryllium nickel copper alloy strip at different deformation temperatures (20℃ to 300℃), and the ratio of the yield strength to the elastic modulus of the final copper niobium composite strip is about 30% to 40% higher than that of the beryllium nickel copper alloy strip, which indicates that the copper niobium composite strip has better springback performance.

[0035] The bending fatigue performance of the copper niobium composite strip prepared in the embodiment is detected, and three samples are selected, and the results are shown in Table 2.

[0036] Table 2 ​

[0037] Sample No. Load Peak (N) Stress Level (%) Cycles (cycles) Test Results 1 753.75 75 22638 Break 2 502.5 50 177402 Break 3 301.5 30 1731494 Break

[0038] As can be seen from Table 2, the number of fatigue cycles that the fracture circle of the copper-niobium composite strip prepared in this embodiment can withstand under 30% of the peak load is 1.7×10 6 Its fatigue performance is close to that of pure copper (the number of cycles before fracture is 5×10 7 times), and is much higher than the fatigue performance of beryllium bronze (the number of cycles before fracture is 2×10 4 times), indicating that the copper-niobium composite plate and strip prepared by the present invention has very excellent fatigue performance.

[0039] The electrical conductivity of the copper-niobium composite strip prepared in this example was tested and compared with the electrical conductivity of the annealed C17510 beryllium-nickel-copper alloy strip. The results are shown in Table 3 below.

[0040] Table 3

[0041] Conductivity Copper-niobium composite strip of Example 1 67.12％ C17510 beryllium-nickel-copper alloy strip 51.96％

[0042] As can be seen from Table 3, the electrical conductivity of the copper-niobium composite strip prepared in this embodiment is higher than that of the beryllium-nickel-copper alloy strip, indicating that its internal nanoscale strongly oriented core wire structure ensures its high strength and high electrical conductivity.

[0043] Figure 3 This is the electron backscattered pattern (EBSD) analysis result of the longitudinal section of the copper-niobium composite plate prepared in this embodiment. Figure 3 It can be seen that the inner core wire of the copper-niobium composite strip has a strong texture orientation.

[0044] Figure 4 This is the SEM image of the copper-niobium nanowire core in the copper-niobium composite strip prepared in this embodiment. Figure 4 It can be seen that the copper and niobium core wire composite structure of the bundled structure in the copper-niobium composite plate and strip is complete and continuous.

[0045] Figure 5 TEM images of the nano niobium core wires in the copper-niobium composite strip prepared in this embodiment are shown in Figure (a), where Figure (b) is a morphology image of the niobium core wires after corrosion of the copper-niobium composite strip, and Figure (c) is a morphology image of a single niobium core wire. The thickness of the niobium core wire is measured to be approximately 96.43 nm. It can be seen that an amorphous layer with a thickness of 5 nm to 10 nm exists at the interface between the niobium core wire and the copper core wire. This low-energy interface layer structure plays an important role in the high-temperature thermal stability of the copper-niobium strip.

[0046] Figure 6 The NS curve of the bending fatigue test of the copper-niobium composite strip prepared in this embodiment is drawn according to the data in Table 2. Figure 6It can be seen directly in combination with Table 2 that the copper-niobium composite plate strip prepared in the embodiment can withstand more cycles of bending, which indicates that the copper-niobium composite plate strip prepared in the embodiment has very excellent fatigue performance.

[0047] Example 2

[0048] The embodiment includes the following steps:

[0049] Step one, high-purity copper foils and high-purity niobium foils with a mass purity of 99.9% and a thickness of 200 μm are alternately and closely stacked together in a layered distribution according to a volume ratio of 1:1, and are formed by winding on an automatic winding device, and then are placed in a copper alloy sheath with an outer diameter of 100 mm and a wall thickness of 8 mm to obtain a copper-niobium wound foil composite sheath, and then the copper-niobium wound foil composite sheath is vacuum degassed and electron beam sealed at both ends, and is subjected to hot extrusion deformation at 700 ℃, so that the high-purity copper foils and the high-purity niobium foils are solid-state welded at the interface, to obtain a copper-niobium composite rod with a winding structure with a diameter of Φ20 mm, and then the copper-niobium composite rod with the winding structure is subjected to multi-pass cold drawing with a pass deformation rate of 12% and intermediate annealing at 700 ℃ for 3 h, to obtain a copper-niobium composite wire with a hexagonal cross section;

[0050] Step two, 853 copper-niobium composite wires with a hexagonal cross section obtained in step one are used as core wires and are assembled in a copper-nickel-tin alloy sheath with an outer diameter of 100 mm to obtain a copper-niobium bundle composite sheath, and then the copper-niobium bundle composite sheath is vacuum sealed at both ends and is subjected to hot extrusion deformation at 750 ℃, so that the outer layer copper alloy interface of the inner core wire is solid-state welded, and the outer layer copper alloy interface of the outer sheath copper alloy and the core wire in contact is solid-state welded, to obtain a copper-niobium bundle composite rod with a multi-core bundle structure with a diameter of 20 mm, and then the copper-niobium bundle composite rod with the multi-core bundle structure is subjected to multi-pass cold drawing with a pass deformation rate of 12%, intermediate annealing at 700 ℃ for 3 h twice, and multi-pass cold drawing with a pass deformation rate of 12%, to obtain a copper alloy / copper / niobium structure composite round wire with a structure of a copper alloy outer layer high-strength wear-resistant copper alloy cladding an internal copper-niobium nanocomposite core wire with high strength, high elasticity, high toughness, high thermal stability and fatigue resistance, as shown in Figure 1 .

[0051] Step three, the copper alloy / copper / niobium structure composite round wire obtained in step three is heat treated at 680°C for 2.5h, and then is subjected to multi-pass cold rolling deformation, and the pass deformation rate of the multi-pass cold rolling deformation is 30% when the cold rolling object has a thickness of 1mm or more, 17% when the cold rolling object has a thickness of 0.5mm or more and less than 1mm, 10% when the cold rolling object has a thickness of 0.3mm or more and less than 0.5mm, and 3% when the cold rolling object has a thickness of less than 0.3mm, and the diameter of the copper alloy / copper / niobium structure composite round wire changes in sequence to 4.4mm, 3.71mm, 3.5mm, 2.98mm, 2.53mm, 2.21mm, 1.89mm, 1.61mm, 1.32mm, 1.07mm, 0.89mm, 0.71mm, 0.55mm, 0.49mm, 0.44mm, 0.38mm, 0.35mm during the multi-pass cold rolling deformation, and finally a high-strength high-elasticity fatigue-resistant wear-resistant and heat-stable copper niobium composite plate strip with a thickness of 0.35mm is obtained, as shown in Figure 2 .

[0052] It is detected that the tensile strength σb of the copper niobium composite plate strip prepared in the embodiment is greater than or equal to 1000MPa, the elastic yield strength / elastic modulus is greater than or equal to 0.008, the cycle loading number N under a stress level of 30% is greater than or equal to 1.7*10 6 times, the softening resistance temperature is greater than or equal to 600°C, and the electrical conductivity is greater than or equal to 65%IACS.

[0053] Example 3

[0054] The embodiment includes the following steps:

[0055] Step one, high-purity copper foils and high-purity niobium foils with a mass purity of 99.9% and a thickness of 500μm are alternately and closely stacked in a layered distribution according to a volume ratio of 1:1 by using a foil automatic winding device, and are then wound and formed on the automatic winding equipment, and then are placed in a copper alloy sleeve with an outer diameter of 120mm and a wall thickness of 8mm to obtain a copper niobium wound foil composite sleeve, and then the copper niobium wound foil composite sleeve is vacuum degassed and electron beam sealed at both ends, and is subjected to hot extrusion deformation at 700°C to make the high-purity copper foils and the high-purity niobium foils interface solid-state welding, and a copper niobium composite rod with a winding structure with a diameter of Φ20mm is obtained, and then the copper niobium composite rod with the winding structure is subjected to multi-pass cold drawing with a pass deformation rate of 15% and intermediate annealing at 680°C for 2.5h to obtain a copper niobium composite wire with a hexagonal cross section;

[0056] Step two, the copper-niobium composite wire with hexagonal cross section obtained in step one is taken as the core wire to be bundled and arranged in a copper-nickel-silicon alloy sheath with an outer diameter of 150 mm to obtain a copper-niobium bundled composite sheath, then the copper-niobium bundled composite sheath is vacuum seal welded at both ends and then is subjected to hot extrusion deformation at 750℃ to make the outer layer copper alloy interface of the inner core wire solid-state welded, the outer sheath copper alloy and the outer layer copper alloy interface of the core wire in contact are solid-state welded, thus a copper-niobium bundled composite rod with a diameter of 20 mm and a multi-core bundled structure is obtained, then the copper-niobium bundled composite rod with a multi-core bundled structure is subjected to multi-pass cold drawing with a pass deformation rate of 10%, intermediate annealing twice at 680℃ for 2.5h, and multi-pass cold drawing with a pass deformation rate of 10%, thus a copper alloy / copper / niobium structure composite round wire with a diameter of φ3.5mm and a structure of copper alloy / copper / niobium nanocomposite core wire with high strength, wear resistance, high elasticity, high toughness, high thermal stability and fatigue resistance is obtained, as shown in Figure 1 ;

[0057] Step three, the copper alloy / copper / niobium structure composite round wire with a diameter of φ3.5mm obtained in step three is subjected to heat treatment at 650℃ for 3h, and then is subjected to multi-pass cold rolling deformation, the pass deformation rate of the multi-pass cold rolling deformation is respectively 25% when the thickness of the cold rolling object is 1mm or more, 15% when the thickness of the cold rolling object is 0.5mm or more and less than 1mm, 5% when the thickness of the cold rolling object is 0.3mm or more and less than 0.5mm, 1% when the thickness of the cold rolling object is less than 0.3mm, and the diameter size of the copper alloy / copper / niobium structure composite round wire changes in turn during the pass cold rolling deformation, which is 3.5mm, 2.98mm, 2.53mm, 2.21mm, 1.89mm, 1.61mm, 1.32mm, 1.07mm, 0.89mm, 0.71mm, 0.55mm, 0.49mm, 0.44mm, 0.38mm, 0.35mm, 0.3mm, 0.25mm, and finally a high-strength high-elasticity fatigue-resistant wear-resistant and thermal-stable copper-niobium composite plate strip with a thickness of 0.25mm is obtained, as shown in Figure 2 .

[0058] It is detected that the tensile strength σb of the copper-niobium composite plate strip prepared in the embodiment is greater than or equal to 1000MPa, the yield strength / elastic modulus is greater than or equal to 0.008, the cycle loading number N under a stress level of 30% is greater than or equal to 1.7×10 6 , the softening resistance temperature is greater than or equal to 600℃, and the electrical conductivity is greater than or equal to 65%IACS.

[0059] Figure 7 The resilience analysis comparison chart of the copper-niobium composite plate strip prepared in the embodiments 1-3 and the beryllium-nickel-copper plate strip is shown in Figure 7It can be seen that, under the same strain, the copper-niobium composite plate strip can completely rebound, while the beryllium-nickel-copper plate strip partially permanently deforms plastically, and through comparison, the rebounding property of the copper-niobium composite plate strip is more excellent.

[0060] The above is only the preferred embodiment of the present application, and does not limit the present application. Any simple modification, change and equivalent change of the above embodiment according to the technical essence of the present application are still within the protection scope of the technical scheme of the present application.

Claims

1. A method for preparing a high-strength, high-elasticity, fatigue-resistant copper-niobium composite plate and strip, characterized in that: The method comprises the following steps: Step 1: Using an automatic foil winding device, high-purity copper foil and high-purity niobium foil of micron-level thickness are alternately wound in a layered distribution at a volume ratio of 1:1, and then placed in a copper alloy sheath to obtain a copper-niobium wound foil composite sheath. The two ends of the copper-niobium wound foil composite sheath are then vacuum-sealed and hot-extruded to form a solid-state welded interface between the high-purity copper foil and the high-purity niobium foil, thereby obtaining a copper-niobium composite rod having a wound structure. The copper-niobium composite rod having a wound structure is then subjected to multiple cold drawing and intermediate annealing to obtain a copper-niobium composite wire having a hexagonal cross-section. The high-purity copper foil and the high-purity niobium foil both have a mass purity of 99.9% and the same thickness, both ranging from 150 μm to 500 μm. The outer diameter of the copper alloy sheath is 80 mm to 120 mm. Step 2: The copper-niobium composite wire with a hexagonal cross-section obtained in Step 1 is used as a core wire for bundling and assembly, and is placed in a copper alloy sheath to obtain a copper-niobium bundled composite sheath. The two ends of the copper-niobium bundled composite sheath are then vacuum-sealed and hot-extruded to ensure that the outer copper alloy interface of the inner core wire is solid-state welded, and the outer sheath copper alloy is solid-state welded with the outer copper alloy interface of the contacting core wire, thereby obtaining a copper-niobium bundled composite rod with a multi-core bundled structure. The copper-niobium bundled composite rod with a multi-core bundled structure is then subjected to multi-pass cold drawing, two intermediate annealings, and multi-pass cold drawing to obtain a copper alloy / copper / niobium structure composite round wire having an outer copper alloy layer and an inner copper-niobium core wire. The outer diameter of the copper alloy sheath is 80 mm to 150 mm. Step 3: heat-treating the copper alloy / copper / niobium composite round wire obtained in step 3, and then performing multiple cold rolling deformation to obtain a high-strength, high-elasticity, fatigue-resistant, wear-resistant, and thermally stable copper-niobium composite strip; the tensile strength of the copper-niobium composite strip is 1000MPa, yield strength / elastic modulus is above 0.008, number of cyclic loading cycles at 30% stress level 1.7×10 6 The softening temperature is above 600℃ and the conductivity is above 65% IACS; the diameter of the copper alloy / copper / niobium structure composite round wire is 3.5mm~ 5.0mm.

2. The method for preparing a high-strength, high-elasticity, fatigue-resistant copper-niobium composite plate and strip according to claim 1, characterized in that: The deformation rate of the multi-pass cold drawing in step 1 is 10% to 15%, and the temperature of the intermediate annealing is 680° C. to 720° C., and the time is 2.5 h to 3 h.

3. The method for preparing a high-strength, high-elasticity, fatigue-resistant copper-niobium composite plate and strip according to claim 1, characterized in that: The copper alloy sheath in step 2 is copper-nickel-silicon or copper-nickel-tin alloy, the temperature of the hot extrusion deformation is 700°C~750°C; the pass deformation rate of the multi-pass cold drawing is 10%~15%, and the intermediate annealing temperature is 680°C~720°C; the copper alloy / copper / niobium structure composite round wire has a structure in which an outer layer of high-strength, wear-resistant copper alloy is coated with an inner copper-niobium nanocomposite core wire with high strength, high elasticity, high toughness, high thermal stability and fatigue resistance.

4. The method for preparing a high-strength, high-elasticity, fatigue-resistant copper-niobium composite plate and strip according to claim 1, characterized in that: The heat treatment temperature in step 3 is 650° C. to 700° C., and the holding time is 2 h to 3 h. The deformation rates of the multiple cold rolling passes are: 25% to 40% when the thickness of the cold rolled strip is 1 mm or more, 15% to 20% when the thickness of the cold rolled strip is 0.5 mm or more and less than 1 mm, 5% to 15% when the thickness of the cold rolled strip is 0.3 mm or more and less than 0.5 mm, and 1% to 5% when the thickness of the cold rolled strip is less than 0.3 mm. The thickness of the copper-niobium composite strip is 0.25 mm to 0.5 mm.

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