Cu-ni-sn alloy with high aging stability and preparation method thereof

Abstract

The application discloses a Cu-Ni-Sn alloy with high time-effect stability and a preparation method thereof, and belongs to the field of material preparation.The method takes Cu, Ni and Sn as basic components, and takes Hf as a main added component, wherein Ni is 7-17%, Sn is 5-12%, Hf is 0.01-0.7%, and the balance is Cu; the Hf element mainly exists in three forms: a solid solution form, a nanoscale precipitated phase formed by being combined with alloy matrix elements Cu, Ni and Sn, and a micron-level segregation phase formed by being combined with alloy matrix elements Cu, Ni and Sn; in a smelting process, Cu, Ni and Sn are used in the form of elements as raw materials, and Hf is used in the form of an intermediate alloy as raw material; the melt is kept in a single-phase zone for a sufficient time, and after the internal composition is uniform, casting is completed; and after solid solution of the casting in the single-phase zone, treatment is carried out at 350-500 DEG C to obtain the Cu-Ni-Sn alloy.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, specifically relating to a Cu-Ni-Sn alloy with high aging stability and its preparation method. Background Technology

[0002] Cu-Ni-Sn alloys, with their high strength and elasticity, good electrical and thermal conductivity, excellent corrosion and wear resistance, and ample welding and machining capabilities, are widely used in various precision instruments, heavy machinery bearings, marine oil and gas, and heavy-duty ship equipment. Furthermore, their stable service life at 250℃ and their non-toxic, environmentally friendly nature make them highly competitive in the market for high-strength, high-elasticity, and wear-resistant copper alloys.

[0003] Cu-Ni-Sn alloy is a type of amplitude-modulated decomposition-strengthened copper alloy, and its excellent properties mainly come from amplitude-modulated decomposition that occurs during the aging process. During aging, the Cu-Ni-Sn alloy primarily exhibits amplitude-modulated decomposition microstructures, (Cu... x Ni 1-x )3Sn ordered structure (D0) 22 ), (Cu x Ni 1-x )3Sn ordered structure (Ll2), discontinuous precipitation (α-FCC and γ-DO3 arranged in alternating lamellar structures), and other four structures, with the transformation sequence being solid solution structure → amplitude modulation structure → DO 22 Ordered phase → Ll2 ordered phase → discontinuous precipitation. Among them, amplitude modulation structure, D0 22 Both ordered phases and Ll2 ordered phases can provide performance enhancement to the alloy through their good coherent relationship with the matrix. However, the presence of discontinuous precipitates (α-FCC and γ-DO3 arranged in alternating lamellar structures) will significantly reduce the strength and plasticity of the alloy, leading to a substantial decrease in the material's mechanical properties. Therefore, how to suppress the formation of harmful discontinuous precipitates during the aging process of Cu-Ni-Sn alloys, improve the aging stability of the alloys, and thus expand the heat treatment window of the alloys is crucial for the development of the alloys.

[0004] As a thermodynamically stable microstructure, harmful discontinuous precipitates (α-FCC and γ-DO3 arranged in alternating lamellar patterns) have a strong tendency to form during aging. They typically begin to appear before the alloy's amplitude modulation (AM) has achieved the desired strengthening effect, often resulting in peak alloy performance falling short of expectations. Furthermore, when using this alloy to produce structurally complex parts, the varying heating rates in different regions during heat treatment often lead to differences in the aging process. Before the part as a whole has received sufficient AM strengthening, some areas have already developed a large amount of harmful discontinuous precipitates (α-FCC and γ-DO3), causing performance deficiencies in certain areas and significantly limiting the alloy's applications. Therefore, the aging stability of the alloy becomes a key factor determining the application areas of Cu-Ni-Sn alloys.

[0005] Based on the above, developing a Cu-Ni-Sn alloy composition system with high aging stability and corresponding preparation technology has become an urgent problem to be solved. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention proposes a Cu-Ni-Sn alloy with high aging stability and its preparation method, aiming to overcome the insufficient aging stability exhibited by existing Cu-Ni-Sn alloys during preparation. This invention provides a Cu-Ni-Sn alloy material with high aging stability. Through the intervention of Hf element, based on strengthening mechanisms such as diffusion inhibition, grain boundary pinning, second-phase strengthening, and microstructure refinement, the alloy exhibits better performance in terms of aging stability, mechanical properties, and wear resistance compared to existing Cu-Ni-Sn alloys.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The present invention discloses a Cu-Ni-Sn alloy with high aging stability, comprising the following chemical components and mass percentages: Ni: 7-17%; Sn: 5-12%; Hf: 0.01-0.7%; balance Cu.

[0009] The Cu-Ni-Sn alloy has a modulated microstructure and contains a large amount of uniform, dispersed D0 atoms that are coherent with the matrix. 22 Phases including the Ll2 ordered phase and the (Ni+Cu)5Hf phase;

[0010] The Cu-Ni-Sn alloy contains dissolved Hf atoms, nanoscale Hf-rich precipitates, and micron-scale Hf-rich segregated phases.

[0011] The Cu-Ni-Sn alloy described above has the ability to maintain stable aging for a long time at 350-500℃, and the failure mode above 500℃ is continuous precipitation.

[0012] The present invention discloses a method for preparing a Cu-Ni-Sn alloy with high aging stability, comprising the following steps:

[0013] Step 1: Alloy Melting

[0014] (1) Copper busbars, nickel plates, tin blocks and Hf master alloys are used as raw materials, and after cutting and ultrasonic cleaning, they are dried;

[0015] (2) Place the copper busbar from step 1 (1) into a crucible in a smelting furnace for smelting. After the copper busbar is completely melted, add the nickel plate from the above ingredients and continue heating until the copper-nickel alloy is completely melted and uniform. Add the tin block from the above ingredients and continue heating until the copper-nickel-tin alloy is completely melted to obtain Cu-Ni-Sn melt.

[0016] Alternatively, place the copper busbar, nickel plate and tin block from step 1(1) into a crucible in a smelting furnace and smelt them until the copper-nickel-tin alloy is completely melted to obtain Cu-Ni-Sn melt;

[0017] (3) Add the Hf intermediate alloy from step 1 (1) to the Cu-Ni-Sn melt in step 1 (2), heat it up and then cast it to obtain an alloy ingot or casting.

[0018] Step 2: Heat treatment of the alloy

[0019] (1) The alloy ingot or casting obtained in step 1 (3) above is subjected to solution treatment to obtain a supersaturated solid solution;

[0020] (2) The solid solution alloy in step 2(1) above is subjected to aging treatment and then cooled to obtain Cu-Ni-Sn alloy.

[0021] The Hf master alloy mentioned in step 1(1) is a Cu-Hf master alloy or a Ni-Hf master alloy; the mass fraction of Hf element in the Hf master alloy is 10-50%;

[0022] The ultrasonic cleaning described in step 1(1) is ultrasonic cleaning with water at room temperature until all the grease on the surface of the raw material is completely removed.

[0023] The drying temperature in step 1(1) is 40-70℃, and the drying time is 1-2h;

[0024] The smelting furnace mentioned in step 1(2) is a vacuum induction smelting furnace, a non-vacuum induction smelting furnace, or a gas furnace;

[0025] The heating process described in step 1(3) is to heat the temperature to 1450-1600℃ and hold it for 20-40 minutes; the casting process is to control the furnace exit temperature at 1150-1350℃ for casting.

[0026] The solution treatment described in step 2(1) specifically involves placing the alloy ingot or casting in a box-type heat treatment furnace for solution treatment, followed by cooling; the solution treatment temperature is 800-900℃, the heating rate is 3-10℃ / min, and the solution treatment time is 1-6h; the cooling method is air cooling, wind cooling, or water cooling.

[0027] The aging treatment described in step 2(2) is as follows: the solid solution alloy is placed in a box-type heat treatment furnace for aging treatment at a temperature of 350-500℃, a heating rate of 3-10℃ / min, and an aging treatment time of 1-12h.

[0028] The Cu-Ni-Sn alloy described in step 2(2) can be used to prepare high-elasticity, high-strength, and wear-resistant copper alloy castings, plates, bars, and profiles.

[0029] The key technical point of this invention lies in the preparation of a Cu-Ni-Sn alloy with high aging stability. Firstly, the alloy uses Cu, Ni, and Sn as basic components, with Hf as the main additive (main chemical composition: Ni mass fraction 7-17%, Sn mass fraction 5-12%, Hf mass fraction 0.01-0.7%, balance Cu). Hf exists primarily in three forms: 1. solid solution form; 2. nanoscale precipitates formed by combining with the alloy matrix elements Cu, Ni, and Sn; 3. micron-scale segregated phases formed by combining with the alloy matrix elements Cu, Ni, and Sn. Secondly, during the smelting process, Cu, Ni, and Sn are used as elemental raw materials, while Hf is added as an intermediate alloy. The melt is held in the single-phase region for a sufficient time until its internal composition is homogeneous before casting. Finally, after solution treatment in the single-phase region, the casting is subjected to sufficient aging treatment at 350-500℃ to take advantage of its excellent aging stability, thereby obtaining sufficient amplitude decomposition strengthening effect and achieving ideal performance.

[0030] The beneficial effects of this invention are as follows: By appropriately introducing Hf element and matching corresponding preparation conditions, a Cu-Ni-Sn alloy with high aging stability is obtained, suppressing the occurrence of discontinuous precipitation of harmful structures during aging treatment, and transforming the thermal failure mode of the alloy from discontinuous precipitation to continuous precipitation. Existing Cu-Ni-Sn alloys show a significant performance decrease after aging at 400℃ for 4-6 hours, while the alloy proposed in this invention maintains stable performance even after aging at 400℃ and 450℃ for 48 hours. Even when the aging temperature is increased to 500℃, no significant discontinuous precipitation structures form during a short aging process (0-6 hours). The improved aging stability of the Cu-Ni-Sn alloy significantly enhances its overall service capability and expands its application fields. Furthermore, the alloy proposed in this invention also exhibits better mechanical properties and wear resistance compared to existing Cu-Ni-Sn alloys.

[0031] This invention proposes a Cu-Ni-Sn alloy with high aging stability and its preparation method. This invention integrates alloy composition and preparation process, achieving effective control of the alloy microstructure, significantly improving its stability during aging, and inducing a shift in the failure mechanism from discontinuous precipitation to continuous precipitation. This invention has advantages such as simple process, low cost, and significant effects, and can greatly improve the stability of the alloy and expand its heat treatment window. Attached Figure Description

[0032] Figure 1 This is a metallographic image illustrating the effect of Hf element intervention on the as-cast microstructure of the alloy in an embodiment of the present invention.

[0033] Figure 2 This is a scanning image showing the effect of Hf element on precipitated phases in the alloy in an embodiment of the present invention;

[0034] Figure 3 This is a metallographic diagram illustrating the effect of Hf element on the aging stability of the alloy in an embodiment of the present invention;

[0035] Figure 4 This is a transmission image showing the effect of Hf element intervention on alloy failure behavior in an embodiment of the present invention. Detailed Implementation

[0036] Example 1: Preparation of Cu-15Ni-8Sn-0.1Hf alloy castings

[0037] Step 1: Preparation of alloy raw materials

[0038] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0039] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0040] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0041] Step 1.4. Weigh 1.54 kg of copper busbar, 0.3 kg of nickel plate, 0.16 kg of pure tin granules, and 40 g of copper-hafnium intermediate alloy.

[0042] Step 2: Melting of Cu-15Ni-8Sn-0.1Hf alloy

[0043] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0044] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0045] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0046] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0047] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0048] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0049] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0050] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0051] Step 3: Heat treatment of Cu-15Ni-8Sn-0.1Hf alloy

[0052] Step 3.1. Place the Cu-15Ni-8Sn-0.1Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and heat the ingot along with the furnace.

[0053] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0054] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0055] Step 3.4. Cool the ingot with water to obtain a supersaturated solid solution.

[0056] Step 3.5. After drying the solution-treated alloy ingot, place it in a box-type heat treatment furnace.

[0057] Step 3.6. Heat the alloy ingot from room temperature to 400°C at a heating rate of 7°C / min.

[0058] Step 3.7. Hold the alloy ingot at 400℃ for 4 hours.

[0059] Step 3.8. Remove the alloy ingot from the furnace and water cool it to obtain the final service structure.

[0060] Example 2: Preparation of Cu-15Ni-8Sn-0.3Hf alloy castings

[0061] Step 1: Preparation of alloy raw materials

[0062] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0063] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0064] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0065] Step 1.4. Weigh 1.48 kg of copper busbar, 0.3 kg of nickel plate, 0.16 kg of pure tin granules, and 120 g of copper-hafnium intermediate alloy.

[0066] Step 2: Melting of Cu-15Ni-8Sn-0.3Hf alloy

[0067] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0068] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0069] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0070] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0071] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0072] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0073] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0074] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0075] Step 3: Heat treatment of Cu-15Ni-8Sn-0.3Hf alloy

[0076] Step 3.1. Place the Cu-15Ni-8Sn-0.3Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and heat the ingot along with the furnace.

[0077] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0078] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0079] Step 3.4. Cool the ingot with water to obtain a supersaturated solid solution.

[0080] Step 3.5. After drying the solution-treated alloy ingot, place it in a box-type heat treatment furnace.

[0081] Step 3.6. Heat the alloy ingot from room temperature to 400°C at a heating rate of 7°C / min.

[0082] Step 3.7. Hold the alloy ingot at 400℃ for 4 hours.

[0083] Step 3.8. Remove the alloy ingot from the furnace and water cool it to obtain the final service structure.

[0084] Example 3: Preparation of Cu-15Ni-8Sn-0.6Hf alloy castings

[0085] Step 1: Preparation of alloy raw materials

[0086] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0087] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0088] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0089] Step 1.4. Weigh 1.36 kg of copper busbar, 0.3 kg of nickel plate, 0.16 kg of pure tin granules, and 240 g of copper-hafnium master alloy.

[0090] Step 2: Melting of Cu-15Ni-8Sn-0.6Hf alloy

[0091] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0092] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0093] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0094] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0095] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0096] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0097] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0098] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0099] Step 3: Heat treatment of Cu-15Ni-8Sn-0.6Hf alloy

[0100] Step 3.1. Place the Cu-15Ni-8Sn-0.6Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and heat the ingot along with the furnace.

[0101] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0102] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0103] Step 3.4. Cool the ingot with water to obtain a supersaturated solid solution.

[0104] Step 3.5. After drying the solution-treated alloy ingot, place it in a box-type heat treatment furnace.

[0105] Step 3.6. Heat the alloy ingot from room temperature to 400°C at a heating rate of 7°C / min.

[0106] Step 3.7. Hold the alloy ingot at 400℃ for 4 hours.

[0107] Step 3.8. Remove the alloy ingot from the furnace and water cool it to obtain the final service structure.

[0108] Example 4: Preparation of Cu-15Ni-8Sn-0.6Hf alloy sheet

[0109] Step 1: Preparation of alloy raw materials

[0110] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0111] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0112] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0113] Step 1.4. Weigh 1.36 kg of copper busbar, 0.3 kg of nickel plate, 0.16 kg of pure tin granules, and 240 g of copper-hafnium master alloy.

[0114] Step 2: Melting of Cu-15Ni-8Sn-0.6Hf alloy

[0115] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0116] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0117] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0118] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0119] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0120] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0121] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0122] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0123] Step 3: Cold rolling treatment of Cu-15Ni-8Sn-0.6Hf alloy

[0124] Step 3.1. Place the Cu-15Ni-8Sn-0.6Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and heat the ingot along with the furnace.

[0125] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0126] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0127] Step 3.4. Cool the ingot with water to obtain a supersaturated solid solution.

[0128] Step 3.5. Remove the surface oxide scale from the solid solution alloy ingot obtained in Step 3.4.

[0129] Step 3.6. Perform alloy ingot blanking at room temperature, controlling the initial deformation amount to be 10-15%.

[0130] Step 3.7. Roll at room temperature, controlling the reduction in pressure per pass to 5-10%.

[0131] Step 3.8. Roll at room temperature to achieve a total deformation of 80% for the alloy.

[0132] Step 4: Heat treatment of Cu-15Ni-8Sn-0.6Hf alloy sheet

[0133] Step 4.1. Place the cold-rolled alloy sheet in a box-type heat treatment furnace.

[0134] Step 4.2. Heat the cold-rolled alloy sheet from room temperature to 400°C at a heating rate of 7°C / min.

[0135] Step 4.3. Hold the cold-rolled alloy sheet at 400℃ for 0.5h.

[0136] Step 4.4. Remove the alloy sheet from the furnace and water cool it to obtain the final service structure.

[0137] Example 5: Preparation of Cu-15Ni-8Sn-0.6Hf alloy bi-stage deformation plate

[0138] Step 1: Preparation of alloy raw materials

[0139] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0140] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0141] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0142] Step 1.4. Weigh 1.36 kg of copper busbar, 0.3 kg of nickel plate, 0.16 kg of pure tin granules, and 240 g of copper-hafnium master alloy.

[0143] Step 2: Melting of Cu-15Ni-8Sn-0.6Hf alloy

[0144] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0145] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0146] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0147] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0148] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0149] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0150] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0151] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0152] Step 3: First cold rolling treatment of Cu-15Ni-8Sn-0.6Hf alloy

[0153] Step 3.1. Place the Cu-15Ni-8Sn-0.6Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and heat the ingot along with the furnace.

[0154] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0155] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0156] Step 3.4. Cool the ingot with water to obtain a supersaturated solid solution.

[0157] Step 3.5. Remove the surface oxide scale from the solid solution alloy ingot obtained in Step 3.4.

[0158] Step 3.6. Perform alloy ingot blanking at room temperature, controlling the initial deformation amount to be 10-15%.

[0159] Step 3.7. Roll at room temperature, controlling the reduction in pressure per pass to 5-10%.

[0160] Step 3.8. Roll at room temperature to achieve a total deformation of 80% for the alloy.

[0161] Step 4: Annealing treatment of Cu-15Ni-8Sn-0.6Hf alloy cold-rolled sheet

[0162] Step 4.1. Place the Cu-15Ni-8Sn-0.6Hf alloy cold-rolled sheet obtained in Step 3 into a box-type heat treatment furnace, and heat the cold-rolled sheet with the furnace.

[0163] Step 4.2. Heat the cold-rolled sheet from room temperature to 875°C at a heating rate of 7°C / min.

[0164] Step 4.3. Hold the cold-rolled sheet at 875℃ for 0.5h.

[0165] Step 4.4. The primary cold-rolled sheet is water-cooled to obtain an annealed primary cold-rolled sheet.

[0166] Step 5: Secondary cold rolling treatment of Cu-15Ni-8Sn-0.6Hf alloy

[0167] Step 5.1. Remove the surface oxide scale from the annealed primary cold-rolled sheet obtained in Step 4.

[0168] Step 5.2. Perform a second cold rolling on the annealed primary cold-rolled sheet at room temperature, controlling the reduction in pressure per pass to 10-15%, until the total deformation reaches 80%.

[0169] Step 6: Heat treatment of Cu-15Ni-8Sn-0.6Hf alloy secondary cold-rolled sheet

[0170] Step 6.1. Place the secondary cold-rolled alloy sheet obtained in Step 5 into a box-type heat treatment furnace.

[0171] Step 6.2. Heat the secondary cold-rolled alloy sheet from room temperature to 400℃ at a heating rate of 7℃ / min.

[0172] Step 6.3. Hold the secondary cold-rolled alloy sheet at 400℃ for 0.5h.

[0173] Step 6.4. Take the secondary cold-rolled sheet out of the furnace and water-cool it to obtain the final service structure.

[0174] Example 6: Preparation of Cu-9Ni-6Sn-0.3Hf alloy castings

[0175] Step 1: Preparation of alloy raw materials

[0176] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0177] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0178] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0179] Step 1.4. Weigh 1.7 kg of copper busbar, 0.18 kg of nickel plate, 0.12 kg of pure tin granules, and 120 g of copper-hafnium master alloy.

[0180] Step 2: Melting of Cu-9Ni-6Sn-0.3Hf alloy

[0181] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0182] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0183] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0184] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0185] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0186] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0187] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0188] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0189] Step 3: Heat treatment of Cu-9Ni-6Sn-0.3Hf alloy

[0190] Step 3.1. Place the Cu-9Ni-6Sn-0.3Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and allow the ingot to heat up with the furnace.

[0191] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0192] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0193] Step 3.4. Cool the ingot with water to obtain a supersaturated solid solution.

[0194] Step 3.5. After drying the solution-treated alloy ingot, place it in a box-type heat treatment furnace.

[0195] Step 3.6. Heat the alloy ingot from room temperature to 400°C at a heating rate of 7°C / min.

[0196] Step 3.7. Hold the alloy ingot at 400℃ for 4 hours.

[0197] Step 3.8. Remove the alloy ingot from the furnace and water cool it to obtain the final service structure.

[0198] Example 7: Preparation of hot-rolled Cu-9Ni-6Sn-0.3Hf alloy sheet

[0199] Step 1: Preparation of alloy raw materials

[0200] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0201] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0202] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0203] Step 1.4. Weigh 1.7 kg of copper busbar, 0.18 kg of nickel plate, 0.12 kg of pure tin granules, and 120 g of copper-hafnium master alloy.

[0204] Step 2: Melting of Cu-9Ni-6Sn-0.3Hf alloy

[0205] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0206] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0207] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0208] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0209] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0210] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0211] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0212] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0213] Step 3: Hot rolling treatment of Cu-9Ni-6Sn-0.3Hf alloy

[0214] Step 3.1. Place the Cu-9Ni-6Sn-0.3Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and allow the ingot to heat up with the furnace.

[0215] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0216] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0217] Step 3.4. Immediately after the ingot is removed from the furnace, it is hot rolled, and the initial deformation is controlled within 10-15%.

[0218] Step 3.5. Perform hot rolling at 800-875℃, controlling the reduction amount in each pass to be 8-12%, so that the total deformation of the alloy reaches 70%, and then water cool to room temperature.

[0219] Step 4: Heat treatment of Cu-9Ni-6Sn-0.3Hf alloy hot-rolled sheet

[0220] Step 4.1. Place the hot-rolled alloy sheet obtained in Step 3 into a box-type heat treatment furnace.

[0221] Step 4.2. Heat the hot-rolled alloy sheet from room temperature to 400°C at a heating rate of 7°C / min.

[0222] Step 4.3. Hold the hot-rolled alloy sheet at 400℃ for 3 hours.

[0223] Step 4.4. Remove the alloy sheet from the furnace and water cool it to obtain the final service structure.

[0224] Example 8: Preparation of cold-rolled Cu-9Ni-6Sn-0.3Hf alloy sheet

[0225] Step 1: Preparation of alloy raw materials

[0226] Step 1.1. Smelt copper-hafnium master alloy using an electric arc furnace, wherein the mass fraction of Hf element is 50%.

[0227] Step 1.2. Cut the copper busbar (purity ≥99.95%), nickel plate (purity ≥99.5%), and tin block (purity ≥99.5%) into strips with a width of less than 30mm using a band saw, and remove the surface grease by ultrasonic cleaning.

[0228] Step 1.3. Dry the raw materials in a drying oven at 60℃ for 2 hours.

[0229] Step 1.4. Weigh 1.7 kg of copper busbar, 0.18 kg of nickel plate, 0.12 kg of pure tin granules, and 120 g of copper-hafnium master alloy.

[0230] Step 2: Melting of Cu-9Ni-6Sn-0.3Hf alloy

[0231] Step 2.1. Place the copper raw material weighed in Step 1 into a crucible inside a medium-frequency vacuum induction melting furnace.

[0232] Step 2.2. Close the furnace chamber and begin evacuation. Wait until the vacuum level inside the furnace chamber reaches 1×10⁻⁶. -2 When the pressure reaches 0.06 MPa, stop evacuating and backflush with argon gas until the pressure is 0.06 MPa.

[0233] Step 2.3. Turn on the intermediate frequency power supply to start melting.

[0234] Step 2.4. After the copper busbar in the crucible has completely melted, add the nickel plate weighed in Step 1 to the molten copper.

[0235] Step 2.5. After heating the copper-nickel melt in the crucible until it is completely and uniformly melted, add the tin block weighed in Step 1 to the alloy melt.

[0236] Step 2.6. After heating the copper-nickel-tin melt in the crucible until it is completely and uniformly melted, add the copper-hafnium master alloy weighed in Step 1 to the alloy melt.

[0237] Step 2.7. Continue heating to 1600℃ and hold for 20 minutes.

[0238] Step 2.8. Control the furnace temperature at 1150-1350℃ and cast the ingot to obtain the casting.

[0239] Step 3: Hot rolling treatment of Cu-9Ni-6Sn-0.3Hf alloy

[0240] Step 3.1. Place the Cu-9Ni-6Sn-0.3Hf alloy ingot obtained in Step 2 into a box-type heat treatment furnace and allow the ingot to heat up with the furnace.

[0241] Step 3.2. Heat the ingot from room temperature to 875°C at a heating rate of 7°C / min.

[0242] Step 3.3. Hold the ingot at 875℃ for 6 hours.

[0243] Step 3.4. Immediately after the ingot is removed from the furnace, it is hot rolled, and the initial deformation is controlled within 10-15%.

[0244] Step 3.5. Perform hot rolling at 800-875℃, controlling the reduction amount in each pass to be 8-12%, so that the total deformation of the alloy reaches 70%, and then water cool to room temperature.

[0245] Step 4: Cold rolling treatment of Cu-9Ni-6Sn-0.3Hf alloy hot-rolled sheet

[0246] Step 4.1. Remove the oxide scale from the surface of the Cu-9Ni-6Sn-0.3Hf alloy hot-rolled sheet obtained in Step 3.

[0247] Step 4.2. Cold roll the Cu-9Ni-6Sn-0.3Hf alloy hot-rolled sheet at room temperature, controlling the deformation amount of the first pass to be 10-15%.

[0248] Step 4.7. Roll at room temperature, controlling the reduction in pressure per pass to 5-10%.

[0249] Step 4.8. Roll at room temperature to achieve a total deformation of 80% for the alloy.

[0250] Step 5: Heat treatment of Cu-9Ni-6Sn-0.3Hf alloy sheet

[0251] Step 5.1. Place the cold-rolled alloy sheet obtained in Step 4 into a box-type heat treatment furnace.

[0252] Step 5.2. Heat the cold-rolled alloy sheet from room temperature to 400°C at a heating rate of 7°C / min.

[0253] Step 5.3. Hold the cold-rolled alloy sheet at 400℃ for 0.5h.

[0254] Step 5.4. Remove the alloy sheet from the furnace and water-cool it to obtain the final service microstructure. In this embodiment of the invention, the effect of Hf element on the as-cast microstructure of the alloy is as follows: Figure 1 As shown; the effect of Hf element on precipitates in the alloy is as follows: Figure 2 As shown; the effect of Hf element on the aging stability of alloys is as follows. Figure 3 As shown; the effect of Hf element intervention on alloy failure behavior is as follows: Figure 4 As shown.

Claims

1. A Cu-Ni-Sn alloy with high aging stability, characterized in that, The chemical components and their mass percentages are as follows: Ni: 7-17%; Sn: 5-12%; Hf: 0.1-0.7%; balance Cu; The Cu-Ni-Sn alloy has a modulated microstructure and contains uniform, dispersed DO atoms that are coherent with the matrix. 22 The Cu-Ni-Sn alloy contains dissolved Hf atoms, nanoscale Hf-rich precipitates, and micron-scale Hf-rich segregated phases.

2. The Cu-Ni-Sn alloy with high aging stability according to claim 1, characterized in that, The Cu-Ni-Sn alloy described above has the ability to maintain stable aging for a long time at 350-500℃, and the failure mode above 500℃ is continuous precipitation.

3. A method for preparing a Cu-Ni-Sn alloy with high aging stability as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: Alloy Melting (1) Copper busbars, nickel plates, tin blocks and Hf master alloys are used as raw materials. After cutting and ultrasonic cleaning, they are dried. (2) Place the copper busbar from step 1 (1) into a crucible in a smelting furnace for smelting. After the copper busbar is completely melted, add a nickel plate and continue heating until the copper-nickel alloy is completely melted and uniform. Add a tin block and continue heating until the copper-nickel-tin alloy is completely melted to obtain Cu-Ni-Sn melt. Alternatively, place the copper busbar, nickel plate and tin block from step 1 (1) into a crucible in a smelting furnace and smelt them until the copper-nickel-tin alloy is completely melted to obtain Cu-Ni-Sn melt; (3) Add the Hf master alloy from step 1 (1) to the Cu-Ni-Sn melt in step 1 (2), heat it up and then cast it to obtain an alloy casting; Step 2: Heat treatment of the alloy (1) The alloy castings obtained in step 1 (3) above are subjected to solution treatment to obtain a supersaturated solid solution; (2) The solid solution alloy in step 2 (1) above is subjected to aging treatment and then cooled to obtain Cu-Ni-Sn alloy.

4. The method for preparing a Cu-Ni-Sn alloy with high aging stability according to claim 3, characterized in that, The Hf master alloy mentioned in step 1 (1) is a Cu-Hf master alloy or a Ni-Hf master alloy; the mass fraction of Hf element in the Hf master alloy is 10-50%; the ultrasonic cleaning is to use water for ultrasonic cleaning at room temperature until the grease on the surface of the raw material is completely removed; the drying temperature is 40-70℃ and the drying time is 1-2h.

5. The method for preparing a Cu-Ni-Sn alloy with high aging stability according to claim 3, characterized in that, The smelting furnace mentioned in step 1 (2) is a vacuum induction smelting furnace, a non-vacuum induction smelting furnace, or a gas furnace.

6. The method for preparing a Cu-Ni-Sn alloy with high aging stability according to claim 3, characterized in that, The heating process described in step 1 (3) is to heat the temperature to 1450-1600℃ and hold it for 20-40 minutes; the casting process is to control the furnace exit temperature at 1150-1350℃ for casting.

7. The method for preparing a Cu-Ni-Sn alloy with high aging stability according to claim 3, characterized in that, The solution treatment described in step 2 (1) specifically involves placing the alloy casting in a box-type heat treatment furnace for solution treatment and then cooling it; the solution treatment temperature is 800-900℃, the heating rate is 3-10℃ / min, and the solution treatment time is 1-6h; the cooling method is air cooling, wind cooling, or water cooling.

8. The method for preparing a Cu-Ni-Sn alloy with high aging stability according to claim 3, characterized in that, The aging treatment described in step 2 (2) specifically involves placing the solid solution alloy in a box-type heat treatment furnace. The aging treatment temperature is 350-500℃, the heating rate is 3-10℃ / min, and the aging treatment time is 1-12h.

9. The method for preparing a Cu-Ni-Sn alloy with high aging stability according to claim 3, characterized in that, The Cu-Ni-Sn alloy described in step 2 (2) is used in the preparation of high-elasticity, high-strength, and wear-resistant copper alloy profiles.

10. The method for preparing a Cu-Ni-Sn alloy with high aging stability according to claim 9, characterized in that, The profiles include plates and rods.

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