Cu-Ni-Sn-Co magnetic copper alloy and preparation method thereof

Abstract

The invention relates to a Cu-Ni-Sn-Co magnetic copper alloy and a preparation method thereof, belongs to the technical field of magnetic nonferrous metals, solves the technical problem of insufficient performance of Cu-Ni-Sn alloys, and adopts the technical scheme that the chemical formula of the magnetic copper alloy is CuyNi15Sn8Cox, and the preparation method comprises the following steps: firstly, weighing raw materials, and carrying out vacuum arc melting to prepare a magnetic copper alloy ingot; then, the magnetic copper alloy cast ingot is put into a vacuum annealing furnace to be annealed, and the annealed magnetic copper alloy cast ingot is taken out and quickly put into water to be quenched; and finally, the annealed magnetic copper alloy cast ingot is rolled, and the Cu-Ni-Sn-Co magnetic copper alloy thin strip is prepared. According to the Cu-Ni-Sn-Co alloy and the preparation method thereof, the alloy performance is improved by designing alloy components and proportions and combining a heat treatment technology and a rolling technology, so that the Cu-Ni-Sn-Co alloy has good magnetic performance and small resistivity, the technological process is simple and easy to implement, and industrial production is easy.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic nonferrous metals, and specifically relates to a Cu-Ni-Sn-Co magnetic copper alloy and a preparation method thereof. Background Art

[0002] Beryllium bronze is a precipitation-hardening copper-based elastic alloy with excellent performance. It not only has high strength, elasticity, wear resistance and fatigue resistance, but also has good electrical conductivity, thermal conductivity, non-magnetic and impact-free spark properties. Therefore, it is widely used in the electronic information industry, aerospace, precision instruments and household appliances. In recent years, with the continuous development of the electronic information industry towards integration, miniaturization, micro-miniaturization and higher reliability and stability, beryllium bronze is often used as an elastic element to manufacture signal switches, connectors, spring parts and relays in electronic information equipment. This requires beryllium bronze products to have higher performance indicators in use. First, the size of the components should be reduced while ensuring the strength of the components. Second, the components should have reliable contact, good electrical conductivity stability and stress relaxation resistance during long-term use. However, the inherent shortcomings of beryllium bronze are also increasingly exposed, and the problems of beryllium bronze components are becoming increasingly prominent, such as poor stress relaxation resistance at high temperatures, low electrical conductivity stability at high temperatures, and large deformation of components after aging. In addition, beryllium bronze inevitably produces toxic dust during production, and the compounds of toxic dust are more toxic. Therefore, as people's environmental awareness continues to increase, the production cost of beryllium bronze is also increasing, so it is urgent to research and develop an alloy that can replace beryllium bronze.

[0003] At present, copper-based elastic alloys with properties similar to beryllium bronze and without Be have been successfully developed, such as Cu-Ni-Sn alloys, Cu-Ni-Al alloys and titanium bronze. Compared with beryllium bronze, Cu-Ni-Sn alloys have high strength, good elasticity and stress relaxation resistance, and are considered to be one of the ideal materials to replace beryllium bronze. As a typical copper-based aging-strengthening alloy, Cu-15Ni-8Sn alloy has performance comparable to that of Cu-Be alloy to a certain extent, and is non-toxic during manufacturing and processing. Therefore, it shows great potential in the application of key components such as high-end connectors, instrumentation sensors, etc. Based on the advantages of Cu-Ni-Sn alloys, this alloy has attracted people's attention in recent years. Many researchers have conducted extensive research on its organization, properties and processing technology, and have achieved certain results.

[0004] However, due to the large difference in melting points of Cu, Ni and Sn, the Cu-Ni-Sn alloy is prone to severe component segregation during the solidification process, resulting in uneven cast structure and deterioration of the alloy's performance. At the same time, due to the discontinuous precipitation (DP) phenomenon during its aging strengthening process, the alloy's plasticity and toughness are reduced, especially in low-temperature environments, where brittle fracture is prone to occur, limiting its further promotion and application in industry. In addition, the magnetic permeability of the Cu-Ni-Sn alloy is extremely low, making it unsuitable for use as a magnetic material. It cannot meet the requirements in application scenarios that require high magnetic properties (such as high magnetic permeability, high coercive force, etc.), and is rarely used to manufacture magnetic components with strict magnetic requirements (such as high-performance magnetic cores, permanent magnets, etc.). In addition, the resistivity of the Cu-15Ni-8Sn alloy is relatively high, making it unsuitable for use as a conductive material. The temperature coefficient of resistivity is also high, and the resistivity changes significantly when the temperature changes. Summary of the invention

[0005] The main purpose of the present invention is to overcome the deficiencies in the prior art and solve the technical problem that the performance of Cu-Ni-Sn alloy is easily deteriorated due to component segregation. The present invention provides a Cu-Ni-Sn-Co magnetic copper alloy and a preparation method thereof.

[0006] The design concept of the present invention is as follows: it is found through research that adding a trace amount of Co element can significantly improve the strength and hardness of the Cu-15Ni-8Sn alloy, while inhibiting the formation of discontinuous precipitation, thereby improving the alloy's anti-aging ability; the addition of Co can also refine the grains, improve the alloy's component segregation, and promote the alloy's spinodal decomposition and ordering process; the addition of Co element will affect the spin decomposition Spinoadl process in the Cu-Ni-Sn alloy, change the composition and structure of the precipitated phase, thereby affecting the alloy's magnetic and mechanical properties.

[0007] The present invention is achieved through the following technical solutions:

[0008] A Cu-Ni-Sn-Co magnetic copper alloy, the chemical formula is: Cu y Ni 15 Sn8 x , where x and y are mass percentages, wherein 0≤x≤22wt%, 57wt%≤y≤77wt%, and x+y+15wt%+8wt%=100wt%.

[0009] Furthermore, the composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 3wt%-7wt%, and the balance is copper.

[0010] Furthermore, the composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 8wt%-12wt%, and the balance is copper.

[0011] Furthermore, the composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 13wt%-17wt%, and the balance is copper.

[0012] Furthermore, the composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 18wt%-22wt%, and the balance is copper.

[0013] Furthermore, the room temperature magnetic property of the Cu-Ni-Sn-Co magnetic copper alloy is 22emu / g, the Vickers hardness is 243HV, the minimum coercive force is 15Oe, the residual magnetization is less than 2emu / g, and the resistivity is 3.46×10 -7 Ω·m.

[0014] A method for preparing the Cu-Ni-Sn-Co magnetic copper alloy as described above comprises the following steps:

[0015] Firstly, raw materials are weighed according to the composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy, and a magnetic copper alloy ingot is prepared by vacuum arc melting;

[0016] Then, the magnetic copper alloy ingot is placed in a vacuum annealing furnace for annealing at a temperature of 800° C. for a holding time of 24 hours, and the annealed magnetic copper alloy ingot is taken out and quickly placed in water for quenching;

[0017] Finally, the annealed magnetic copper alloy ingot is rolled with a total reduction of 19% to 31% to obtain a Cu-Ni-Sn-Co magnetic copper alloy thin strip.

[0018] The beneficial effects of the present invention are:

[0019] (1) By adjusting the ratio of alloy components and combining heat treatment and rolling processes to improve alloy properties, the Cu-Ni-Sn-Co alloy has good magnetic properties and low resistivity;

[0020] (2) The raw materials Cu, Ni, Sn and Co required for the magnetic alloy provided by the present invention are low in price and abundant in reserves. At the same time, the alloy is non-toxic and has good thermal conductivity and performance stability;

[0021] (3) The present invention adopts conventional smelting equipment to prepare the alloy, and the process is simple and easy to implement, and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a metallographic micrograph of Cu-Ni-Sn-Co alloy, and the scale bar is 200 microns;

[0023] Figure 2 X-ray diffraction spectrum of the cast Cu-Ni-Sn-Co alloy;

[0024] Figure 3 Thermomagnetic curve (MT) of the magnetization intensity M of Cu-Ni-Sn-Co alloy after annealing in 1kOe magnetic field versus temperature T;

[0025] Figure 4 is the isothermal magnetization curve (MH) of the magnetization intensity M of the Cu-Ni-Sn-Co alloy after annealing at 300K as a function of the external magnetic field H;

[0026] Figure 5 The (RT) curve of the resistance R of Cu-Ni-Sn-Co alloy after annealing without an external magnetic field versus temperature T;

[0027] Figure 6 The microhardness changes of Cu-Ni-Sn-Co alloy before and after annealing;

[0028] Figure 7 Isothermal magnetization curves (MH) of the Cu-Ni-Sn-Co alloy in the cast and annealed state after rolling treatment at 300K, where the magnetization intensity M changes with the external magnetic field H;

[0029] Figure 8 The resistance-temperature curve (RT) of Cu-Ni-Sn-Co alloy D in the cast and annealed states after rolling treatment without an external magnetic field. DETAILED DESCRIPTION

[0030] This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0031] Note: The Chinese meanings of the English letters in this manual are as follows:

[0032] Oe is the magnetic field intensity, in oersted;

[0033] M is the magnetization intensity, in emu / g;

[0034] K is the thermodynamic temperature, in calvins;

[0035] k is the English abbreviation for "thousand";

[0036] MT is the magneto-thermal curve;

[0037] MH is the isothermal magnetization curve;

[0038] FC is cooling under magnetic field, i.e. Field Cooling;

[0039] FH stands for heating under magnetic field, i.e. Field Heating.

[0040] The present invention is described in detail below with reference to the embodiments.

[0041] A Cu-Ni-Sn-Co magnetic copper alloy, the chemical formula is: Cu y Ni 15 Sn8 x , where x and y are mass percentages, wherein 0≤x≤22wt%, 57wt%≤y≤77wt%, and x+y+15wt%+8wt%=100wt%. Cu-Ni-Sn-Co magnetic copper alloy has magnetic properties and electrical conductivity.

[0042] The electron configuration of Co atom is 1s 2 2s 2 2p 6 3s 2 3p 6 3d 7 4s 2 , the valence electron configuration is 3d 7 4s 2 The situation that the 3d orbital is half-filled and has electron distribution with the 4s orbital makes the electronic structure of cobalt more complicated. The 7 electrons in the 3d orbital are not fully filled, and there are many unpaired electrons. These unpaired electrons make the cobalt atom have strong spin magnetic moment and orbital magnetic moment, which is one of the important reasons why cobalt has magnetism.

[0043] Cobalt is one of the few elements that has ferromagnetism at room temperature. Ferromagnetism means that cobalt can be magnetized and can maintain strong magnetism after magnetization. Even if the external magnetic field is removed, cobalt can still maintain a certain degree of magnetism. This property makes cobalt have important application value in the manufacture of permanent magnets, magnetic materials, etc.

[0044] In this specific embodiment, five alloy compositions and proportions (respectively marked as AE) are designed, as shown in Table 1 below.

[0045] Table 1 Composition and ratio of Cu-Ni-Sn-Co magnetic copper alloy

[0046]

[0047] Figure 1Figure 1 shows the metallographic micrographs of the above five Cu-Ni-Sn-Co magnetic copper alloys AE under a metallographic microscope. Metallographic microscope observation revealed that the five alloys all showed a dendrite structure, and the alloy structure had three main components: granular or bone-like Sn-rich areas, transitional tissue between dendrites and bone tissue, and α-Cu matrix. Figure 1 It can be seen that the addition of Co element shortens the dendrites and reduces the grain size of the granular or bone-like Sn-rich region. The finer grain size can improve the mechanical properties of the alloy, such as strength and ductility. In addition, Co is distributed evenly in the alloy, and no insoluble particles related to Co are observed.

[0048] Figure 2 The X-ray diffraction spectrum of Cu-Ni-Sn-Co alloy is shown in FIG. Figure 2 It can be seen that the alloy is mainly composed of copper matrix and there is no second phase, indicating that the solute atoms (Ni, Sn and Co) can be fully dissolved into the copper matrix at this time.

[0049] A method for preparing the Cu-Ni-Sn-Co magnetic copper alloy as described above comprises the following steps:

[0050] S1. Raw materials are weighed according to the compositions and mass percentages of five Cu-Ni-Sn-Co magnetic copper alloys AE, and magnetic copper alloy ingots are prepared by vacuum arc melting.

[0051] S2. Place the five Cu-Ni-Sn-Co magnetic copper alloy ingots of AE in a vacuum annealing furnace for annealing at a temperature of 800°C and a holding time of 24 h. Take out the annealed magnetic copper alloy ingots and quickly place them in water for quenching.

[0052] In this embodiment, five Cu-Ni-Sn-Co magnetic copper alloys AE were annealed at a temperature of 800°C, and the magneto-thermal curves (MT) of the five alloys before and after annealing were measured using a vibrating sample magnetometer (VSM). The test conditions were: the external magnetic field intensity was 1 kOe, and the test temperature range was 150-380K. Figure 3 The figure shows the change of alloy magnetic properties with temperature, where alloy A does not contain cobalt, which shows that the magnetic properties of the alloy increase after annealing.

[0053] On this basis, the isothermal magnetization curves of five Cu-Ni-Sn-Co magnetic copper alloys before and after annealing at room temperature (with an applied magnetic field strength of 10 kOe) were measured by VSM. Figure 4 As shown, from Figure 4The residual magnetization, saturation magnetization and coercivity of the alloy can be obtained. Table 2 shows the specific data of the residual magnetization, saturation magnetization and coercivity of the alloy. At room temperature, the magnetic properties of alloy D can reach 18emu / g, the residual magnetization is less than 2emu / g, and the coercivity is 159Oe.

[0054] Table 2

[0055]

[0056] Furthermore, the resistance variation of five Cu-Ni-Sn-Co magnetic copper alloys AE with temperature was measured by VSM. The one-word four-wire method was used for testing. The test temperature range was 150-380K, and the cooling and heating processes were measured at the same time. Figure 5 The resistance-temperature (RT) curve of the alloy after annealing without an external magnetic field is shown.

[0057] Resistivity is an important indicator of the electrical properties of alloys. The calculation formula of resistivity is: ρ = R × S / L, where ρ represents resistivity, R represents resistance, L represents resistance length, and S represents resistance cross-sectional area. In order to ensure the consistency of resistivity testing, alloy sheets with consistent length, width, and height are used as much as possible during testing. Table 3 shows the specific data of resistivity before and after alloy annealing. It can be noted that the resistivity of alloy D after annealing is 58% of that of alloy A.

[0058] Table 3

[0059]

[0060] Furthermore, the Vickers hardness of the five Cu-Ni-Sn-Co magnetic copper alloys AE was tested using a microhardness tester. Figure 6 Table 4 shows the Vickers hardness of the alloy before and after annealing. Table 5 shows the specific data of the Vickers hardness of the alloy. It can be seen that the Vickers hardness of the unannealed E alloy can reach 243.6HV, indicating that the addition of Co element can improve the hardness of the alloy.

[0061] Table 4

[0062]

[0063] S3. Rolling the annealed magnetic copper alloy ingot with a total reduction of 19%-31% to obtain a Cu-Ni-Sn-Co magnetic copper alloy thin strip.

[0064] In this embodiment, the alloy D before and after annealing was subjected to cold rolling process, the applied pressure was 10MPa, and the deformation after cold rolling was 31% and 19% respectively. The isothermal magnetization curve of the alloy D before and after annealing and after cold rolling at room temperature was measured by VSM (the applied magnetic field intensity was 10kOe). Figure 7 Figure 2 shows the magnetization curves of alloy D at room temperature after cold rolling before and after annealing. Figure 7 The residual magnetization, saturation magnetization and coercivity of the alloy can be obtained from Table 5. Table 5 shows the specific data of the residual magnetization, saturation magnetization and coercivity of the alloy.

[0065] Table 5

[0066]

[0067] The resistance variation of the D alloy after cold rolling before and after annealing was measured by VSM, and the test temperature range was 250-350K. Figure 8 The resistance versus temperature (RT) curves of the D alloy after cold rolling before and after annealing without an external magnetic field are shown in Table 6. The specific data of the resistivity of the D alloy after cold rolling before and after annealing are shown in Table 6. It can be seen that the resistivity of the D alloy before annealing is further reduced after rolling, reaching 3.46×10 -7 Ω·m is 22% of that of the unannealed A alloy. It can be seen that annealing can significantly reduce the resistivity of the D alloy.

[0068] Table 6

[0069]

[0070] The Vickers hardness of the D alloy after rolling before and after annealing was tested using a microhardness tester. Table 7 shows the specific data of the Vickers hardness. The Vickers hardness of the D alloy after rolling before and after annealing is improved, but the hardness of the annealed copper alloy strip after rolling is improved more.

[0071] Table 7

[0072]

[0073] In summary, the Cu-Ni-Sn-Co magnetic copper alloy prepared by the present invention has the characteristics of low resistivity and large magnetism, and provides a valuable way for making magnetic connecting wires.

[0074] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A Cu-Ni-Sn-Co magnetic copper alloy, characterized in that: The chemical formula of the Cu-Ni-Sn-Co magnetic copper alloy is: Cu y Ni 15 Sn8 x , where x and y are mass percentages, wherein 0≤x≤22wt%, 57wt%≤y≤77wt%, and x+y+15wt%+8wt%=100wt%.

2. A Cu-Ni-Sn-Co magnetic copper alloy according to claim 1, characterized in that: The composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 3wt%-7wt%, and the balance is copper.

3. The Cu-Ni-Sn-Co magnetic copper alloy according to claim 1, characterized in that: The composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 8wt%-12wt%, and the balance is copper.

4. The Cu-Ni-Sn-Co magnetic copper alloy according to claim 1, characterized in that: The composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 13wt%-17wt%, and the balance is copper.

5. The Cu-Ni-Sn-Co magnetic copper alloy according to claim 1, characterized in that: The composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy are: Ni: 15wt%, Sn: 8wt%, Co: 18wt%-22wt%, and the balance is copper.

6. The Cu-Ni-Sn-Co magnetic copper alloy according to claim 1, characterized in that: The room temperature magnetic property of the Cu-Ni-Sn-Co magnetic copper alloy is 22emu / g, the Vickers hardness is 243HV, the minimum coercive force is 15Oe, the residual magnetization is less than 2emu / g, and the resistivity is 5.97×10 -7 Ω·m.

7. A method for preparing the Cu-Ni-Sn-Co magnetic copper alloy according to any one of claims 1 to 6, characterized in that: The following steps are involved: Firstly, raw materials are weighed according to the composition and mass percentage of the Cu-Ni-Sn-Co magnetic copper alloy, and a magnetic copper alloy ingot is prepared by vacuum arc melting; Then, the magnetic copper alloy ingot is placed in a vacuum annealing furnace for annealing at a temperature of 800° C. for a holding time of 24 hours, and the annealed magnetic copper alloy ingot is taken out and quickly placed in water for quenching; Finally, the annealed magnetic copper alloy ingot is rolled with a total reduction of 19%-31% to obtain a Cu-Ni-Sn-Co magnetic copper alloy strip.

Images