High thermal conductivity copper-zirconium alloy and preparation method thereof

Abstract

The application relates to the technical field of alloy materials, in particular to a high-thermal-conductivity copper-zirconium alloy and a preparation method thereof, which comprises the following steps: raw material pretreatment, segmented vacuum melting, gradient solidification forming and gradient aging modification; the third-stage cooling end temperature of the gradient solidification forming is consistent with the first-stage temperature rising starting temperature of the gradient aging modification, and the holding time of the gradient solidification forming and the holding time of the gradient aging modification are matched in a ratio of 1:0.05-0.08; in the technical scheme, the raw material pretreatment link serves as the basis of the preparation process, the raw materials such as electrolytic copper and zirconium blocks are processed to a specific size range, and the consistency of the melting rate of the raw materials in the melting process is ensured; the combination mode of vacuum drying, nitrogen blowing and closed transfer removes the water and impurities adsorbed on the surface of the raw materials from the source, simultaneously avoids oxidation caused by air contact in the transfer process, and provides raw material purity guarantee for the uniformity of the subsequent alloy components.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, specifically to a high thermal conductivity copper-zirconium alloy and its preparation method. Background Technology

[0002] In aerospace, high-end electronic information, and other fields, the operating environment of electronic components is becoming increasingly complex, placing higher demands on conductor materials used for power and signal transmission. These materials not only require excellent thermal conductivity to dissipate heat quickly but also sufficient mechanical strength to withstand harsh operating conditions. Copper-zirconium alloys, with their potential for combining excellent strength and thermal conductivity, have become one of the key research materials in these high-end fields.

[0003] However, current copper-zirconium alloy preparation technology still faces many unresolved issues. In the raw material processing stage, traditional processes lack sufficient control over raw material dimensions, and oxidation or impurity adsorption easily occurs during drying and transportation, affecting the uniformity of the alloy composition. During smelting, conventional heating methods are insufficient to achieve complete fusion of raw materials, easily leading to compositional segregation. Furthermore, coarse grains and bubble defects in the molten alloy are difficult to eliminate effectively, directly impacting the alloy's fundamental properties. In the solidification stage, improper cooling rate control often results in internal stress or cracks in the ingot, while the lack of coordinated design between aging treatment and solidification process parameters leads to uneven distribution of precipitated phases, failing to fully realize the strengthening effect.

[0004] Therefore, developing a preparation method that can achieve synergistic coordination among various process steps and effectively improve the overall performance of copper-zirconium alloys has become an urgent need in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a high thermal conductivity copper-zirconium alloy and its preparation method.

[0006] The specific technical solution is as follows: A method for preparing a high thermal conductivity copper-zirconium alloy includes the following steps: raw material pretreatment, segmented vacuum melting, gradient solidification forming, and gradient aging modification; the cooling endpoint temperature of the third stage of gradient solidification forming is consistent with the heating start temperature of the first stage of gradient aging modification, and the holding time of gradient solidification forming is adapted to the holding time of gradient aging modification in a ratio of 1:0.05-0.08 to achieve synergistic control of Cu3Zr strengthening phase precipitation and distribution.

[0007] As a further technical solution, the raw material pretreatment step includes: selecting pure electrolytic copper, pure zirconium blocks, pure iron particles, silicon particles, and pure nickel particles; cutting the electrolytic copper into copper blocks of 6-8 mm, processing the zirconium blocks into zirconium particles of 3-4 mm, and screening the iron particles, silicon particles, and nickel particles into particles of 2-3 mm; placing the above raw materials in a vacuum drying oven and drying them at 130-140℃ for 5-6 hours; during the drying process, nitrogen gas is introduced for circulating purging, and the nitrogen purging rate is 0.25-0.3 L / min.

[0008] As a further technical solution, after the raw materials are dried, a closed transfer device protected by nitrogen is used to transfer the raw materials to the feed inlet of the smelting furnace. During the transfer process, the nitrogen atmosphere pressure is maintained at 0.1-0.12MPa. This pressure range is determined according to the bulk density of the raw material particles, which can prevent the raw material particles from being blown up by nitrogen or the infiltration of outside air. The pressure control accuracy is ±0.01MPa.

[0009] As a further technical solution, the segmented vacuum melting step includes: adding the pretreated raw materials to a vacuum induction melting furnace according to the specified ratio, evacuating the furnace to a vacuum degree ≤15Pa, and introducing argon gas with a purity ≥99.999% as a protective gas at a flow rate of 0.7-0.9L / min; segmented heating melting: the first stage involves heating to 850-880℃ at a rate of 20-25℃ / min and holding for 35-40min, with the initial heating condition being that the furnace temperature stabilizes at room temperature ±5℃; the second stage involves heating to 1270-1290℃ at a rate of 15-20℃ / min and holding for 70-80min, with the initial heating condition being that the furnace temperature stabilizes at 850-880℃ ±5℃, and electromagnetic stirring performed every 15min during this period. The stirring rate is 350-380 r / min, and the stirring mode is intermittent variable speed stirring with a speed fluctuation range of ±20 r / min and a fluctuation period of 5 min. In the third stage, the temperature is increased to 1370-1390℃ at a rate of 10-15℃ / min and held for 25-30 min. The initial heating condition is that the furnace temperature is stable at 1270-1290℃±5℃. At the same time, ultrasonic vibration is applied with an ultrasonic vibration power of 150-180W and a frequency of 30-35kHz. The vibration probe is inserted into the alloy liquid to a depth of 60-70mm, and the vibration mode is intermittent vibration, vibrating for 10 min and stopping for 2 min. The continuous working time of the ultrasonic vibration at 1370-1390℃ does not exceed 30 min to ensure the high temperature resistance and stability of the titanium alloy probe.

[0010] As a further technical solution, the ultrasonic vibration probe is made of titanium alloy, and the probe surface is coated with an aluminum nitride wear-resistant coating with a coating thickness of 0.05-0.1mm.

[0011] As a further technical solution, the gradient solidification molding step includes: pouring the alloy melt into a graphite mold at a rate of 5-8 kg / min under argon protection, preheating the graphite mold to 320-340℃, and matching the pouring rate with the mold preheating temperature at a ratio of 20-25 kg / (min·℃); placing the mold containing the alloy melt into a gradient cooling furnace and cooling it according to the following procedure: the first stage is cooling to 820-840℃ at a rate of 6-7℃ / min and holding for 25-30 min; the second stage is cooling to 520-540℃ at a rate of 12-14℃ / min and holding for 45-50 min; and the third stage is cooling to room temperature at a rate of 2-3℃ / min.

[0012] As a further technical solution, the graphite mold preheating adopts a gradient heating program: heating from room temperature to 320-340℃ at a rate of 12-14℃ / min, holding at that temperature for 10-15min before pouring; during the cooling process, argon gas is introduced for protection from the first stage of cooling, with an argon gas flow rate of 0.3-0.5L / min to ensure no oxidation throughout the cooling process.

[0013] As a further technical solution, the gradient aging modification step includes: first, homogenizing the copper-zirconium alloy ingot by holding it at 970-990℃ for 9-10 hours, followed by cooling it to room temperature at a rate of 4-5℃ / min. Argon gas is introduced for protection during the homogenization process, with a flow rate of 0.4-0.5 L / min. The homogenization temperature is 100-120℃ lower than the solidus temperature of the copper-zirconium alloy to prevent abnormal grain growth in the ingot; then, the homogenized ingot is placed in… The aging furnace is used for the following stages: first stage, holding at 270-290℃ for 2.5-3 hours; second stage, holding at 420-440℃ for 7-8 hours; and third stage, holding at 520-540℃ for 1.5-2 hours. During the second stage, a pulsed magnetic field is applied with a strength of 0.5-1.0T and a frequency of 50-100Hz. After aging, the ingot is cooled to room temperature in the furnace. After the homogenized ingot has cooled to room temperature, it is transferred to the aging furnace for heating within 2 hours to reduce oxidation on the ingot surface.

[0014] As a further technical solution, the surface of the ingot after homogenization is ground to a thickness of 0.5-1mm; during the application of the pulsed magnetic field, the direction of the magnetic field is consistent with the axis of the ingot, the magnetic field strength fluctuates periodically, the fluctuation amplitude is ±0.1T, the fluctuation period is 10min, and the fluctuation amplitude control accuracy is ±0.005T.

[0015] The preparation method described above yields the high thermal conductivity copper-zirconium alloy, which has the following composition: 40.19% zirconium, 0.10% iron, 0.006% silicon, 0.003% nickel, with the balance being copper; the total mass percentage of each component is 100%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In this invention, the raw material pretreatment step serves as the foundation of the preparation process. By processing raw materials such as electrolytic copper and zirconium blocks to a specific size range, the consistency of the melting rate of the raw materials during the smelting process is ensured. The combination of vacuum drying, nitrogen purging, and closed transport removes moisture and impurities adsorbed on the surface of the raw materials from the source, while avoiding oxidation caused by contact with air during transport, thus ensuring the purity of the raw materials for the uniformity of the subsequent alloy composition.

[0017] Segmented vacuum melting is a key step in improving the microstructure quality of alloys. The multi-stage heating and holding process follows the thermodynamic laws of raw material melting and component diffusion. The first stage, preheating, removes trace amounts of moisture and gas. The second stage, medium-temperature holding combined with intermittent variable-speed electromagnetic stirring, breaks the concentration gradient in the melt through periodic rate fluctuations, promoting uniform mixing of components and effectively suppressing component segregation. The third stage, high-temperature holding, applies ultrasonic vibration, utilizing the high-frequency vibration energy transmitted by a titanium alloy probe, which breaks up coarse grains and bubbles formed in the melt, refining the alloy grain size.

[0018] Gradient solidification molding, through the synergy of gradient preheating of a graphite mold and a multi-stage cooling process, solves the internal stress problem caused by sudden temperature changes during traditional solidification. Gradient heating of the mold ensures a smooth temperature transition after the alloy molten metal is poured. The first stage of slow cooling and holding promotes uniform grain growth, the second stage of moderately accelerated cooling refines the grains, and the third stage of low-speed cooling further releases internal stress, preventing ingot cracking. Argon gas protection throughout the process effectively prevents oxidation of the alloy during cooling, ultimately resulting in an ingot with a uniform microstructure and no obvious defects, providing a good structural foundation for subsequent aging modification.

[0019] In the gradient aging modification process, homogenization treatment eliminates component segregation and internal stress inside the ingot through high-temperature holding, and grinding removes the surface oxide scale, avoiding the impact of the oxide layer on the aging effect. The segmented aging process, based on the nucleation and growth law of the precipitates, achieves the gradual refinement and uniform distribution of the precipitates through holding in different temperature ranges. The pulsed magnetic field applied in the second stage promotes the nucleation rate of the precipitates through the periodic fluctuation of the magnetic force. At the same time, the design of the magnetic field direction being consistent with the ingot axis ensures that the precipitates are uniformly distributed along the force direction, further improving the structural stability and mechanical properties of the alloy. The requirement to transfer the ingot to the aging furnace within 2 hours after homogenization treatment avoids secondary oxidation of the ingot or the regeneration of stress, ensuring the stability of the aging effect.

[0020] The grain refinement achieved by ultrasonic vibration in segmented vacuum melting provides a more uniform microstructure for gradient solidification, resulting in more consistent grain growth direction and more uniform internal stress distribution during solidification. Conversely, the low-stress, uniform microstructure obtained through gradient solidification creates favorable conditions for the uniform nucleation of precipitates during gradient aging modification, preventing precipitate aggregation caused by microstructure inhomogeneity. This synergy in microstructure optimization allows the alloy's microstructure to progressively advance from grain refinement to microstructure homogenization and then to precipitation strengthening, ultimately achieving comprehensive microstructure optimization.

[0021] The optimal matching of parameters between gradient solidification and gradient aging modification is the core of their synergistic effect. The consistency between the cooling endpoint temperature of the third stage of gradient solidification and the heating start temperature of the first stage of gradient aging modification avoids secondary stress caused by sudden temperature changes in the ingot during the initial aging heating phase, ensuring the stability of the nucleation environment for precipitates. The matching ratio of holding times (1:0.05-0.08) allows the microstructure formed during solidification to fully complete the nucleation and growth of precipitates during the aging stage. This avoids insufficient precipitation due to insufficient holding time and coarse precipitates due to excessive holding time, maximizing the microstructure strengthening effect.

[0022] The electromagnetic stirring in segmented vacuum melting, combined with ultrasonic vibration and the pulsed magnetic field of gradient aging modification, creates a synergistic strengthening effect across processes. The compositional homogeneity promoted by electromagnetic stirring provides a uniform material basis for the grain refinement by ultrasonic vibration, while the grain refinement by ultrasonic vibration provides more nucleation sites for the uniform distribution of precipitates under the action of the pulsed magnetic field. The uniform distribution of precipitates promoted by the pulsed magnetic field further hinders grain growth in subsequent processes, forming a virtuous cycle of compositional homogeneity, grain refinement, and precipitation strengthening, ultimately achieving a simultaneous and significant improvement in the thermal conductivity and mechanical properties of the alloy. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for preparing a high thermal conductivity copper-zirconium alloy. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a method for preparing a high thermal conductivity copper-zirconium alloy, comprising the following steps: raw material pretreatment, segmented vacuum melting, gradient solidification forming, and gradient aging modification; the cooling endpoint temperature of the third stage of gradient solidification forming is consistent with the heating start temperature of the first stage of gradient aging modification, and the holding time of gradient solidification forming is adapted to the holding time of gradient aging modification in a ratio of 1:0.05-0.08.

[0026] Raw material pretreatment: The present invention first involves a raw material pretreatment step. In this invention, the selected raw materials are pure electrolytic copper, pure zirconium blocks, pure iron granules, silicon granules, and pure nickel granules. The purity of each raw material must meet the basic requirements for preparing a high thermal conductivity copper-zirconium alloy, and commercially available products well-known to those skilled in the art can be used.

[0027] After selecting the raw materials, they are processed in terms of size: electrolytic copper is cut into copper blocks of 6-8 mm, zirconium blocks are processed into zirconium granules of 3-4 mm, and iron, silicon, and nickel granules are screened into particles of 2-3 mm. After size processing, the above raw materials are placed in a vacuum drying oven and dried at 130-140℃ for 5-6 hours. During the drying process, nitrogen gas is circulated and purged at a rate of 0.25-0.3 L / min. Nitrogen purging can effectively remove moisture and impurities adsorbed on the surface of the raw materials, avoiding defects such as bubbles during subsequent smelting.

[0028] After the raw materials are dried, a closed transfer device protected by nitrogen is used to transfer the raw materials to the feed inlet of the smelting furnace. During the transfer process, the nitrogen atmosphere pressure is maintained at 0.1-0.12MPa to prevent the raw materials from oxidizing due to contact with air during the transfer process and to ensure the purity of the raw materials.

[0029] Segmented vacuum melting: After the raw materials are transferred to the inlet of the melting furnace, a segmented vacuum melting process is carried out. The pretreated raw materials are added to the vacuum induction melting furnace according to the following proportions: zirconium 40.19%, iron 0.10%, silicon 0.006%, nickel 0.003%, and the balance is copper, with a total mass percentage of 100%.

[0030] The vacuum induction melting furnace is evacuated to a vacuum level of ≤15Pa. Then, argon gas with a purity of ≥99.999% is introduced as a protective gas at a flow rate of 0.7-0.9L / min. Argon protection can prevent the alloy melt from being oxidized during the melting process.

[0031] Then, the process involves staged heating and smelting: The first stage involves heating the material at a rate of 20-25℃ / min to 850-880℃ and holding it at that temperature for 35-40 minutes. The initial heating condition is that the furnace temperature is stable at room temperature ±5℃. This stage mainly involves preheating the raw materials and gradually removing any residual trace amounts of moisture and gas.

[0032] The second stage involves heating to 1270-1290℃ at a rate of 15-20℃ / min and holding at that temperature for 70-80min. The initial heating condition is that the furnace temperature is stabilized at 850-880℃±5℃. During this period, electromagnetic stirring is performed every 15min at a stirring rate of 350-380r / min. The stirring mode is intermittent variable speed stirring with a speed fluctuation range of ±20r / min and a fluctuation period of 5min. Electromagnetic stirring can make the alloy melt composition more uniform and avoid compositional segregation.

[0033] The third stage involves heating to 1370-1390℃ at a rate of 10-15℃ / min and holding at that temperature for 25-30 minutes. The initial heating condition is that the furnace temperature stabilizes at 1270-1290℃ ± 5℃. Simultaneously, ultrasonic vibration is applied with a power of 150-180W and a frequency of 30-35kHz. The vibration probe is inserted into the molten alloy to a depth of 60-70mm, and the vibration mode is intermittent, vibrating for 10 minutes and then stopping for 2 minutes. The continuous ultrasonic vibration at 1370-1390℃ should not exceed 30 minutes. Ultrasonic vibration can break up coarse grains in the molten alloy, refine the grain structure, and improve the mechanical and thermal conductivity of the alloy.

[0034] In this invention, the ultrasonic vibration probe is made of titanium alloy, and the probe surface is coated with an aluminum nitride wear-resistant coating with a coating thickness of 0.05-0.1mm. Titanium alloy has good high temperature resistance and mechanical strength, and the aluminum nitride wear-resistant coating can improve the wear resistance of the probe and extend its service life.

[0035] Gradient solidification molding: After the segmented vacuum melting is completed, a gradient solidification forming step is performed. The molten alloy is poured into a graphite mold at a rate of 5-8 kg / min under argon protection. The graphite mold needs to be preheated using a gradient heating program: from room temperature to 320-340℃ at a rate of 12-14℃ / min, held for 10-15 minutes, and then poured. The pouring rate is 20-25 kg / (min) relative to the mold preheating temperature. Matching the ratio of ℃, a reasonable pouring rate and mold preheating temperature can prevent defects such as cracks caused by a sudden drop in temperature during the pouring process of the alloy melt.

[0036] Place the mold containing the molten alloy into a gradient cooling furnace and cool it according to the following procedure: The first stage involves cooling to 820-840℃ at a rate of 6-7℃ / min and holding at that temperature for 25-30min. The second stage involves cooling to 520-540℃ at a rate of 12-14℃ / min and holding at that temperature for 45-50min. The third stage involves cooling to room temperature at a rate of 2-3℃ / min.

[0037] During the cooling process, argon gas is introduced for protection starting from the first stage of cooling, with an argon gas flow rate of 0.3-0.5 L / min, to prevent the alloy from being oxidized during the cooling process.

[0038] Gradient-age modification: After gradient solidification is completed, gradient aging modification is performed. First, the copper-zirconium alloy ingot is homogenized. Before homogenization, the surface of the ingot is polished to a thickness of 0.5-1mm to remove oxide scale and impurities.

[0039] The homogenization process involves holding at 970-990℃ for 9-10 hours, followed by cooling to room temperature at a rate of 4-5℃ / min. Argon gas is introduced for protection during the homogenization process, with a flow rate of 0.4-0.5L / min. The homogenization temperature is 100-120℃ lower than the solidus temperature of the copper-zirconium alloy to prevent abnormal grain growth in the ingot. Homogenization can eliminate compositional segregation and internal stress inside the ingot, laying a good foundation for subsequent aging treatment.

[0040] After the homogenized ingot is cooled to room temperature, it is transferred to an aging furnace within 2 hours for heating, and the following aging stages are performed sequentially: The first stage involves maintaining a temperature of 270-290℃ for 2.5-3 hours. The second stage involves holding the alloy at 420-440℃ for 7-8 hours. During this stage, a pulsed magnetic field is applied with a strength of 0.5-1.0T and a frequency of 50-100Hz. The direction of the magnetic field is consistent with the axis of the ingot, and the magnetic field strength fluctuates periodically with a fluctuation amplitude of ±0.1T and a fluctuation period of 10 minutes. The fluctuation amplitude is controlled with an accuracy of ±0.005T. The application of the pulsed magnetic field can promote the uniform precipitation of precipitates inside the alloy, thereby improving the thermal conductivity and mechanical properties of the alloy. The third stage involves maintaining the temperature at 520-540℃ for 1.5-2 hours.

[0041] After aging, the alloy is cooled to room temperature in the furnace to obtain a high thermal conductivity copper-zirconium alloy.

[0042] The method for preparing high thermal conductivity copper-zirconium alloy provided by this invention, through the synergistic effect of raw material pretreatment, segmented vacuum melting, gradient solidification, and gradient aging modification, especially the adaptive design of process parameters for gradient solidification and gradient aging modification, can effectively refine alloy grains, eliminate compositional segregation and internal stress, and promote the uniform distribution of precipitated phases, thereby significantly improving the thermal conductivity and mechanical properties of copper-zirconium alloy. At the same time, this preparation method is stable, easy to control, and can achieve large-scale production, solving the problems of poor thermal conductivity, unstable mechanical properties, and low production efficiency of copper-zirconium alloy in traditional preparation methods.

[0043] To further illustrate the present invention, the following detailed description is provided through the examples and comparative examples.

[0044] Example 1: Raw material pretreatment: Pure electrolytic copper, pure zirconium blocks, pure iron granules, silicon granules, and pure nickel granules were selected. The electrolytic copper was cut into 6mm copper blocks, the zirconium blocks were processed into 3mm zirconium granules, and the iron, silicon, and nickel granules were screened into 2mm particles. The above raw materials were placed in a vacuum drying oven and dried at 130℃ for 5 hours. During the drying process, nitrogen gas was purged in a circulating manner at a rate of 0.25L / min. After the raw materials were dried, a nitrogen-protected closed transfer device was used to transfer the raw materials to the inlet of the smelting furnace, maintaining a nitrogen atmosphere pressure of 0.1MPa during the transfer process.

[0045] Segmented vacuum melting: The pretreated raw materials are added to a vacuum induction melting furnace according to the mass percentages of zirconium 40.19%, iron 0.10%, silicon 0.006%, nickel 0.003%, and the balance copper. The furnace is evacuated to a vacuum level ≤15 Pa, and argon gas with a purity ≥99.999% is introduced as a protective gas at a flow rate of 0.7 L / min. Segmented heating melting: In the first stage, the temperature is increased to 850℃ at a rate of 20℃ / min and held for 35 min. The initial heating condition is that the furnace temperature stabilizes at room temperature ±5℃. In the second stage, the temperature is increased to 1270℃ at a rate of 15℃ / min and held for 70 min. The initial heating condition is that the furnace temperature stabilizes at 850℃ ±5℃. Electromagnetic stirring was performed every 15 minutes at a stirring rate of 350 r / min. The stirring mode was intermittent variable speed stirring with a speed fluctuation range of ±20 r / min and a fluctuation period of 5 minutes. In the third stage, the temperature was increased to 1370℃ at a rate of 10℃ / min and held for 25 minutes. The initial heating condition was that the furnace temperature was stabilized at 1270℃±5℃. At the same time, ultrasonic vibration was applied with an ultrasonic vibration power of 150W and a frequency of 30kHz. The vibration probe was inserted into the alloy liquid to a depth of 60mm and the vibration mode was intermittent, vibrating for 10 minutes and stopping for 2 minutes. The ultrasonic vibration probe was made of titanium alloy and the probe surface was coated with an aluminum nitride wear-resistant coating with a coating thickness of 0.05mm.

[0046] Gradient solidification molding: The molten alloy is poured into a graphite mold at a rate of 5 kg / min under argon protection. The graphite mold is preheated using a gradient heating program: the temperature is increased from room temperature to 320°C at a rate of 12°C / min, held for 10 min, and then poured. The pouring rate is proportional to the mold preheating temperature at a rate of 20 kg / min. The alloy molten metal was matched in proportion (℃); the mold containing the alloy molten metal was placed in a gradient cooling furnace and cooled according to the following procedure: the first stage was cooled to 820℃ at a rate of 6℃ / min and held for 25min; the second stage was cooled to 520℃ at a rate of 12℃ / min and held for 45min; the third stage was cooled to room temperature at a rate of 2℃ / min; during the cooling process, argon gas was introduced for protection from the first stage of cooling, and the argon gas flow rate was 0.3L / min.

[0047] Gradient aging modification: First, the surface of the copper-zirconium alloy ingot is polished to a thickness of 0.5 mm; then, it undergoes homogenization treatment, which involves holding at 970℃ for 9 hours, followed by cooling to room temperature at a rate of 4℃ / min. Argon gas is introduced for protection during the homogenization process, with a flow rate of 0.4 L / min. After cooling to room temperature, the homogenized ingot is transferred to an aging furnace within 2 hours for heating, followed by the following stages: first stage, holding at 270℃ for 2.5 hours; second stage, holding at 420℃ for 7 hours, with a pulsed magnetic field applied at a strength of 0.5 T and a frequency of 50 Hz, the magnetic field direction being consistent with the ingot axis, the magnetic field strength fluctuating periodically with a fluctuation amplitude of ±0.1 T and a fluctuation period of 10 minutes, and the fluctuation amplitude control accuracy being ±0.005 T; third stage, holding at 520℃ for 1.5 hours; after aging, the ingot is cooled to room temperature in the furnace to obtain a high thermal conductivity copper-zirconium alloy.

[0048] Example 2: Raw material pretreatment: Pure electrolytic copper, pure zirconium blocks, pure iron granules, silicon granules, and pure nickel granules were selected. The electrolytic copper was cut into 7mm copper blocks, the zirconium blocks were processed into 3.5mm zirconium granules, and the iron, silicon, and nickel granules were screened into 2.5mm particles. The above raw materials were placed in a vacuum drying oven and dried at 135℃ for 5.5 hours. During the drying process, nitrogen gas was purged in a circulating manner at a purging rate of 0.28 L / min. After the raw materials were dried, a nitrogen-protected closed transfer device was used to transfer the raw materials to the inlet of the smelting furnace. During the transfer process, the nitrogen atmosphere pressure was maintained at 0.11 MPa.

[0049] Segmented vacuum melting: The pretreated raw materials are added to a vacuum induction melting furnace according to the mass percentages of zirconium 40.19%, iron 0.10%, silicon 0.006%, nickel 0.003%, and the balance copper. The furnace is evacuated to a vacuum level ≤15 Pa, and argon gas with a purity ≥99.999% is introduced as a protective gas at a flow rate of 0.8 L / min. Segmented heating melting: In the first stage, the temperature is increased to 865℃ at a rate of 23℃ / min and held for 38 min. The initial heating condition is that the furnace temperature stabilizes at room temperature ±5℃. In the second stage, the temperature is increased to 1280℃ at a rate of 18℃ / min and held for 75 min. The initial heating condition is that the furnace temperature stabilizes at 865℃ ±5℃. Electromagnetic stirring was performed every 15 minutes at a stirring rate of 365 r / min. The stirring mode was intermittent variable speed stirring with a speed fluctuation range of ±20 r / min and a fluctuation period of 5 minutes. In the third stage, the temperature was increased to 1380℃ at a rate of 13℃ / min and held for 28 minutes. The initial heating condition was that the furnace temperature was stabilized at 1280℃±5℃. At the same time, ultrasonic vibration was applied with an ultrasonic vibration power of 165W and a frequency of 33kHz. The vibration probe was inserted into the alloy liquid to a depth of 65mm and the vibration mode was intermittent, vibrating for 10 minutes and stopping for 2 minutes. The ultrasonic vibration probe was made of titanium alloy and the probe surface was coated with an aluminum nitride wear-resistant coating with a coating thickness of 0.08mm.

[0050] Gradient solidification forming: The alloy molten metal is poured into a graphite mold at a rate of 6.5 kg / min under argon protection. The graphite mold is preheated using a gradient heating program: the temperature is increased from room temperature to 330°C at a rate of 13°C / min, held for 13 min, and then poured. The pouring rate is proportional to the mold preheating temperature at a ratio of 23 kg / (min). The alloy molten metal was matched in proportion (℃); the mold containing the alloy molten metal was placed in a gradient cooling furnace and cooled according to the following procedure: the first stage was cooled to 830℃ at a rate of 6.5℃ / min and held for 28min; the second stage was cooled to 530℃ at a rate of 13℃ / min and held for 48min; the third stage was cooled to room temperature at a rate of 2.5℃ / min; during the cooling process, argon gas was introduced for protection from the beginning of the first stage of cooling, and the argon gas flow rate was 0.4L / min.

[0051] Gradient aging modification: First, the surface of the copper-zirconium alloy ingot is polished to a thickness of 0.8 mm; then, it undergoes homogenization treatment, which involves holding at 980℃ for 9.5 h, followed by cooling to room temperature at a rate of 4.5℃ / min. Argon gas is introduced for protection during the homogenization process, with a flow rate of 0.45 L / min. After cooling to room temperature, the homogenized ingot is transferred to an aging furnace within 2 h for heating, followed by the following stages: first stage, holding at 280℃ for 2.8 h; second stage, holding at 430℃ for 7.5 h, with a pulsed magnetic field applied. The pulsed magnetic field strength is 0.8 T, the frequency is 80 Hz, the magnetic field direction is consistent with the ingot axis, the magnetic field strength fluctuates periodically with a fluctuation amplitude of ±0.1 T, a fluctuation period of 10 min, and a fluctuation amplitude control accuracy of ±0.005 T; third stage, holding at 530℃ for 1.8 h. After aging, the ingot is cooled to room temperature in the furnace to obtain a high thermal conductivity copper-zirconium alloy.

[0052] Example 3: Raw material pretreatment: Pure electrolytic copper, pure zirconium blocks, pure iron granules, silicon granules, and pure nickel granules were selected. The electrolytic copper was cut into 8mm copper blocks, the zirconium blocks were processed into 4mm zirconium granules, and the iron, silicon, and nickel granules were screened into 3mm particles. The above raw materials were placed in a vacuum drying oven and dried at 140℃ for 6 hours. During the drying process, nitrogen gas was purged in a circulating manner at a rate of 0.3L / min. After the raw materials were dried, a nitrogen-protected closed transfer device was used to transfer the raw materials to the inlet of the smelting furnace. During the transfer process, the nitrogen atmosphere pressure was maintained at 0.12MPa.

[0053] Segmented Vacuum Melting: The pretreated raw materials are added to a vacuum induction melting furnace according to the mass percentages of zirconium 40.19%, iron 0.10%, silicon 0.006%, nickel 0.003%, and the balance copper. The furnace is evacuated to a vacuum level ≤15 Pa, and argon gas with a purity ≥99.999% is introduced as a protective gas at a flow rate of 0.9 L / min. Segmented Heating Melting: In the first stage, the temperature is increased to 880℃ at a rate of 25℃ / min and held for 40 min. The initial heating condition is that the furnace temperature stabilizes at room temperature ±5℃. In the second stage, the temperature is increased to 1290℃ at a rate of 20℃ / min and held for 80 min. The initial heating condition is that the furnace temperature stabilizes at 880℃ ±5℃. Electromagnetic stirring was performed every 15 minutes at a stirring rate of 380 r / min. The stirring mode was intermittent variable speed stirring with a speed fluctuation range of ±20 r / min and a fluctuation period of 5 minutes. In the third stage, the temperature was increased to 1390℃ at a rate of 15℃ / min and held for 30 minutes. The initial heating condition was that the furnace temperature was stabilized at 1290℃±5℃. At the same time, ultrasonic vibration was applied with an ultrasonic vibration power of 180W and a frequency of 35kHz. The vibration probe was inserted into the alloy liquid to a depth of 70mm and the vibration mode was intermittent, vibrating for 10 minutes and stopping for 2 minutes. The ultrasonic vibration probe was made of titanium alloy and the probe surface was coated with an aluminum nitride wear-resistant coating with a coating thickness of 0.1mm.

[0054] Gradient solidification forming: The molten alloy is poured into a graphite mold at a rate of 8 kg / min under argon protection. The graphite mold is preheated using a gradient heating program: the temperature is increased from room temperature to 340℃ at a rate of 14℃ / min, held for 15 min, and then poured. The pouring rate is proportional to the mold preheating temperature at a rate of 25 kg / (min). The alloy molten metal was matched in proportion (℃); the mold containing the alloy molten metal was placed in a gradient cooling furnace and cooled according to the following procedure: the first stage was cooled to 840℃ at a rate of 7℃ / min and held for 30min; the second stage was cooled to 540℃ at a rate of 14℃ / min and held for 50min; the third stage was cooled to room temperature at a rate of 3℃ / min; during the cooling process, argon gas was introduced for protection from the first stage of cooling, and the argon gas flow rate was 0.5L / min.

[0055] Gradient aging modification: First, the surface of the copper-zirconium alloy ingot is polished to a thickness of 1 mm; then, it undergoes homogenization treatment, which involves holding at 990℃ for 10 hours, followed by cooling to room temperature at a rate of 5℃ / min. Argon gas is introduced for protection during the homogenization process, with a flow rate of 0.5 L / min. After cooling to room temperature, the homogenized ingot is transferred to an aging furnace within 2 hours for heating, followed by the following stages: first stage, holding at 290℃ for 3 hours; second stage, holding at 440℃ for 8 hours, with a pulsed magnetic field applied. The pulsed magnetic field strength is 1.0 T, the frequency is 100 Hz, the magnetic field direction is consistent with the ingot axis, the magnetic field strength fluctuates periodically with a fluctuation amplitude of ±0.1 T, a fluctuation period of 10 minutes, and a fluctuation amplitude control accuracy of ±0.005 T; third stage, holding at 540℃ for 2 hours. After aging, the ingot is cooled to room temperature in the furnace to obtain a high thermal conductivity copper-zirconium alloy.

[0056] Comparative Example 1: The preparation method of Example 2 was adopted, with the following difference: the cooling endpoint temperature of the third stage of gradient solidification molding was inconsistent with the heating start temperature of the first stage of gradient aging modification. The third stage of gradient solidification molding was cooled to room temperature, while the heating start temperature of the first stage of gradient aging modification was 280℃. Furthermore, the holding time of gradient solidification molding and the holding time of gradient aging modification were not adapted in a ratio of 1:0.05-0.08. The total holding time of gradient solidification molding was 101 min, while the total holding time of gradient aging modification was 13 h (the ratio was approximately 1:0.21).

[0057] Comparative Example 2: The preparation method of Example 2 was used, except that ultrasonic vibration was not applied in the third stage of the segmented vacuum melting.

[0058] Comparative Example 3: The preparation method of Example 2 is used, except that no pulsed magnetic field is applied in the second stage of gradient aging modification.

[0059] Experiment 1: Thermal conductivity test The thermal conductivity of the copper-zirconium alloys prepared in Examples 1-3 and Comparative Examples 1-3 was tested using the hot-wire method. The sample size was Φ20mm × 5mm, the test temperature was 25℃, and each sample was tested three times. The average value was taken as the final test result. The experimental results are as follows: Table 1

[0060] As can be seen from Table 1, the thermal conductivity of the copper-zirconium alloys prepared in Examples 1-3 is all around 328 W / (m²). K) and above indicate that the preparation method of the present invention can effectively improve the thermal conductivity of copper-zirconium alloy.

[0061] The thermal conductivity of Comparative Example 1 is only 285 W / (m²). The reason for this is that the process parameters of gradient solidification and gradient aging modification are not compatible. The cooling endpoint temperature of the third stage of gradient solidification is inconsistent with the heating start temperature of the first stage of gradient aging modification, which leads to secondary stress in the alloy. In addition, the improper holding time ratio results in uneven precipitation of the precipitated phase, thus affecting the thermal conductivity.

[0062] Comparative Example 2 did not apply ultrasonic vibration in the third stage of segmented vacuum melting, and its thermal conductivity was 298 W / (m). Ultrasonic vibration can break up coarse grains in molten alloy, refine the grain structure, and reduce the obstruction of heat conduction by grain boundaries. Without ultrasonic vibration, the alloy grains are relatively coarse, and the thermal conductivity decreases.

[0063] Comparative Example 3 did not have a pulsed magnetic field applied during the second stage of gradient aging modification, and its thermal conductivity was 305 W / (m²). Pulsed magnetic fields can promote the uniform precipitation of precipitates inside the alloy. Uniformly distributed precipitates can reduce scattering during heat conduction and improve thermal conductivity. Without the action of pulsed magnetic fields, the precipitates are unevenly distributed, and the thermal conductivity is affected.

[0064] Experiment 2: Mechanical property testing; Tensile strength test: The copper-zirconium alloys prepared in Examples 1-3 and Comparative Examples 1-3 were tested using a universal testing machine. The test samples were standard round bar specimens with a diameter of 10 mm and a gauge length of 50 mm. The tensile rate was 2 mm / min, and each sample was tested 3 times. The average value was taken as the final test result.

[0065] Hardness Testing: The copper-zirconium alloys prepared in Examples 1-3 and Comparative Examples 1-3 were tested using a Brinell hardness tester. The test load was 3000 N, and the loading time was 10 s. Five different test points were selected for each sample, and the average value was taken as the final test result. The test results are as follows: Table 2

[0066] As can be seen from Table 2, the tensile strength of the copper-zirconium alloys prepared in Examples 1-3 is all above 685 MPa and the Brinell hardness is all above 198 HBW, indicating that the preparation method of the present invention can significantly improve the mechanical properties of copper-zirconium alloys.

[0067] The tensile strength of Comparative Example 1 is 598 MPa, and the Brinell hardness is 175 HBW. Due to the mismatch between the gradient solidification forming and gradient aging modification process parameters, there is a large internal stress and compositional segregation in the alloy, which leads to a decrease in the mechanical properties of the alloy, making it prone to fracture under stress, and the hardness is also reduced accordingly.

[0068] Comparative Example 2, without ultrasonic vibration, exhibited a tensile strength of 625 MPa and a Brinell hardness of 182 HBW. The absence of the grain-refining effect of ultrasonic vibration resulted in coarse alloy grains, low grain boundary strength, and easy grain boundary slippage under stress, leading to a decrease in tensile strength and hardness.

[0069] Comparative Example 3, without the application of a pulsed magnetic field, exhibited a tensile strength of 638 MPa and a Brinell hardness of 186 HBW. The pulsed magnetic field promotes uniform precipitation of the precipitate phase, which in turn provides dispersion strengthening, improving the alloy's mechanical properties. Conversely, without the pulsed magnetic field, the precipitate phase distribution is uneven, resulting in poor strengthening and inferior mechanical properties compared to the examples.

[0070] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A method for producing a high thermal conductivity copper-zirconium alloy, characterized by, Includes the following steps: Raw material pretreatment, segmented vacuum melting, gradient solidification molding, and gradient aging modification; the cooling endpoint temperature of the third stage of gradient solidification molding is consistent with the heating start temperature of the first stage of gradient aging modification, and the holding time of gradient solidification molding is adapted to the holding time of gradient aging modification in a ratio of 1:0.05-0.

08.

2. The preparation method according to claim 1, characterized in that, The raw material pretreatment steps include: selecting pure electrolytic copper, pure zirconium blocks, pure iron particles, silicon particles, and pure nickel particles; cutting the electrolytic copper into 6-8 mm copper blocks, processing the zirconium blocks into 3-4 mm zirconium particles, and screening the iron particles, silicon particles, and nickel particles into 2-3 mm particles; placing the above raw materials in a vacuum drying oven and drying them at 130-140℃ for 5-6 hours; during the drying process, nitrogen gas is introduced for circulating purging at a rate of 0.25-0.3 L / min.

3. The preparation method according to claim 2, characterized in that, After the raw materials are dried, a closed transfer device protected by nitrogen is used to transfer the raw materials to the feed inlet of the smelting furnace. During the transfer process, the nitrogen atmosphere pressure is maintained at 0.1-0.12 MPa.

4. The preparation method according to claim 1, characterized in that, The segmented vacuum melting process includes: adding the pretreated raw materials to a vacuum induction melting furnace according to the specified ratio, evacuating the furnace to a vacuum level ≤15Pa, and introducing argon gas with a purity ≥99.999% as a protective gas at a flow rate of 0.7-0.9L / min; and segmented heating melting: the first stage involves heating to 850-880℃ at a rate of 20-25℃ / min and holding for 35-40min, with the initial heating condition being that the furnace temperature stabilizes at room temperature ±5℃; the second stage involves heating to 1270-1290℃ at a rate of 15-20℃ / min and holding for 70-80min, with the initial heating condition being that the furnace temperature stabilizes at 850-880℃ ±5℃, and electromagnetic heating is performed every 15min during this period. The stirring process is as follows: Stirring is performed at a rate of 350-380 r / min, using intermittent variable-speed stirring with a fluctuation range of ±20 r / min and a fluctuation period of 5 min. In the third stage, the temperature is increased to 1370-1390℃ at a rate of 10-15℃ / min and held for 25-30 min. The initial heating condition is that the furnace temperature stabilizes at 1270-1290℃ ±5℃. Simultaneously, ultrasonic vibration is applied with a power of 150-180W and a frequency of 30-35kHz. The vibration probe is inserted into the molten alloy to a depth of 60-70 mm, using intermittent vibration, vibrating for 10 min and then stopping for 2 min. The continuous working time of the ultrasonic vibration at 1370-1390℃ does not exceed 30 min.

5. The preparation method according to claim 4, characterized in that, The ultrasonic vibration probe is made of titanium alloy, and the probe surface is coated with an aluminum nitride wear-resistant coating with a coating thickness of 0.05-0.1mm.

6. The preparation method according to claim 1, characterized in that, The gradient solidification molding step includes: pouring the alloy molten liquid into a graphite mold at a rate of 5-8 kg / min under argon protection; preheating the graphite mold to 320-340°C; matching the pouring rate with the mold preheating temperature at a ratio of 20-25 kg / (min·°C); placing the mold containing the alloy molten liquid into a gradient cooling furnace and cooling it according to the following procedure: in the first stage, cooling to 820-840°C at a rate of 6-7°C / min and holding for 25-30 min; in the second stage, cooling to 520-540°C at a rate of 12-14°C / min and holding for 45-50 min; and in the third stage, cooling to room temperature at a rate of 2-3°C / min.

7. The preparation method according to claim 6, characterized in that, The graphite mold is preheated using a gradient heating program: the temperature is increased from room temperature to 320-340℃ at a rate of 12-14℃ / min, and held for 10-15 minutes before pouring; during the cooling process, argon gas is introduced for protection from the first stage of cooling, with an argon gas flow rate of 0.3-0.5L / min.

8. The preparation method according to claim 1, characterized in that, The gradient aging modification steps include: first, homogenizing the copper-zirconium alloy ingot by holding it at 970-990℃ for 9-10 hours, followed by cooling it to room temperature at a rate of 4-5℃ / min. During the homogenization process, argon gas is introduced for protection at a flow rate of 0.4-0.5L / min, and the homogenization temperature is 100-120℃ lower than the solidus temperature of the copper-zirconium alloy. The homogenized ingot is then placed in an aging furnace and subjected to the following sequential processes: first stage, holding at 270-290℃ for 2.5-3 hours; second stage, holding at 420-440℃ for 7-8 hours; and third stage, holding at 520-540℃ for 1.5-2 hours. During the second stage, a pulsed magnetic field is applied with a strength of 0.5-1.0T and a frequency of 50-100Hz. After aging, the ingot is cooled to room temperature in the furnace. After the homogenized ingot has cooled to room temperature, it is transferred to the aging furnace for heating within 2 hours.

9. The preparation method according to claim 8, characterized in that, The surface of the ingot after homogenization is polished to a thickness of 0.5-1mm. During the application of the pulsed magnetic field, the direction of the magnetic field is consistent with the axis of the ingot, the magnetic field strength fluctuates periodically, the fluctuation amplitude is ±0.1T, the fluctuation period is 10min, and the fluctuation amplitude control accuracy is ±0.005T.

10. The high thermal conductivity copper-zirconium alloy obtained by the preparation method according to any one of claims 1-9, characterized in that, The copper-zirconium alloy has the following composition: 40.19% zirconium, 0.10% iron, 0.006% silicon, 0.003% nickel, with the balance being copper; the total mass percentage of each component is 100%.

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