A Cu-Fe alloy material with high strength, high conductivity and high heat resistance and a preparation method thereof

Abstract

The application discloses a Cu-Fe alloy material with high strength, high conductivity and high heat resistance and a preparation method thereof. The Cu-Fe alloy material comprises the following components in percentage by mass: Fe: 0.8-3%, Mg: 0.05-0.2%, Si: 0-0.1%, Nb: 0-0.2%, V: 0-0.1%, P: 0-0.1%, and the balance is Cu, and the total mass percentage of Si, V, P and Nb is less than 0.2%. The preparation method is as follows: the rapid processing effect of electric pulse is combined with the water quenching process to rapidly fix the work-hardened organizational state, so that the dislocation density and the organizational distortion state can be reserved, and thus the Cu-Fe alloy material with high strength, high conductivity and high heat resistance is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new copper alloy materials, and particularly relates to a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance and a preparation method thereof. BACKGROUND

[0002] The Cu-Fe-P alloy has good strength and electrical conductivity, and is currently a mainstream material applied to integrated circuit lead frames due to low cost and good processability. As a key structural element for semiconductor packaging, the lead frame material needs to ensure the rapid and lossless transmission of electrical signals, withstand various stresses in the packaging and use processes without being easily broken, and effectively transfer and withstand the heat generated during the operation of the chip to prevent overheating failure. This not only requires the material to have high electrical conductivity and strength, but also needs to have excellent high-temperature softening resistance. The electrical conductivity of the commonly used Cu-Fe-P lead frame material reaches more than 60% IACS, the hardness reaches 120-150 HV, and the softening temperature is 400-500 DEG C. In more complex and harsh high-temperature service environments such as aerospace and nuclear industry, the softening of the material will make it unable to effectively support the normal operation of the chip, thereby causing damage to the circuit.

[0003] At present, the preparation of heat-treatable non-ferrous metal materials mostly adopts the process of "ingot casting-hot rolling-processing-aging". However, the traditional solid solution treatment needs to be carried out at high temperature (about 0.9Ts, Ts is the melting point of the alloy) for a long time, which is high in energy consumption and easy to form a surface oxide layer that is difficult to remove, affecting the product quality. In addition, the solid solution treatment easily causes abnormal grain growth and uneven size distribution, resulting in uneven structure and decreased mechanical properties; the coarse and uneven copper matrix grains after the solid solution treatment will intensify the uneven deformation during cold rolling, resulting in residual stress concentration, poor surface quality, low size precision, and even cracks or fractures. Therefore, the preparation process of the Cu-Fe-P alloy often omits the solid solution process, but this will also lead to poor composition uniformity of the plate, especially the second phase, which greatly reduces the strengthening effect, thereby reducing the performance stability of the plate. In addition, although the aging treatment can precipitate the strengthening phase, the structure is still in the form of elongated fibers in the peak aging state, and the anisotropy is serious, especially the bending resistance and toughness are low, which is difficult to meet the deep processing and high safety requirements. SUMMARY

[0004] In view of the deficiencies of the prior art, a first object of the present application is to provide a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance.

[0005] A second object of the present application is to provide a preparation method of the Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance.

[0006] In order to achieve the above object, the present application adopts the following technical solutions:

[0007] The present application provides a Cu-Fe alloy material with high strength, high conductivity and high heat resistance, the composition of which is as follows in terms of mass percentage: Fe: 0.8-3%, Mg: 0.05-0.2%, Si: 0-0.1%, Nb: 0-0.2%, V: 0-0.1%, P: 0-0.1%, and the balance being Cu, with the total mass percentage of Si, V, P and Nb being <0.2%.

[0008] The present application uses a lower content of Fe element than the prior art, which greatly reduces the scattering effect of impurity atoms on electrons, and is more conducive to improving the conductivity of Cu-Fe alloy, and promotes the application of Cu-Fe alloy in the fields of electronic information and transportation. On the other hand, the main strengthening effect of Cu-Fe alloy with low Fe content is derived from work hardening, and the α-Fe phase precipitated by aging will rapidly coarsen at high temperature, weakening the interaction between dislocation substructure generated by processing and precipitated phase, thereby greatly reducing the strength and heat resistance of the alloy. Based on this, the present application adds Mg element, which can effectively delay the precipitation phase change of α-Fe phase and inhibit the rapid coarsening of α-Fe phase at high temperature. Meanwhile, Mg element itself can form stable magnesium compounds at high temperature, improving the thermal stability and softening resistance of the material. On the other hand, by adding trace elements Si, V, P and Nb, they can form heat-resistant primary second phases such as Fe3Si and Fe3P with Cu-Fe alloy. By adding more trace elements, multiple-scale heat-resistant second phases are formed in Cu-Fe alloy, and appropriate trace elements can further refine the grains, inhibit grain growth and improve the mechanical properties of the material, thereby synergistically enhancing the work hardening effect and forming a high-strength, high-conductivity and heat-resistant Cu-Fe alloy under the synergistic action of multiple strengthening mechanisms.

[0009] However, it can be seen that the total content of alloying elements in the present application is strictly controlled within a reasonable range, especially the total mass percentage of elements sensitive to electrical conductivity (such as Si, V, P and Nb) is limited to <0.2%. In this way, the strength can be improved while the influence on the conductivity of the copper matrix is minimized, ensuring that the alloy has high electrical conductivity, and avoiding the brittleness or other negative effects caused by too many impurity elements, so that the alloy has excellent ductility and comprehensive performance while maintaining high strength and heat resistance.

[0010] The present application successfully balances the high strength, high conductivity and heat resistance of Cu-Fe alloy material, making the Cu-Fe alloy suitable for high-performance electrical materials and high-temperature application scenarios.

[0011] Preferably, the Cu-Fe alloy material has the following composition in mass percentage: Fe: 1.5-3%, Mg: 0.05-0.15%, Si: 0-0.05%, Nb: 0-0.05%, V: 0-0.05%, P: 0-0.05%, and the balance being Cu.

[0012] Further preferably, the Cu-Fe alloy material has the following composition in mass percentage: Fe: 2.0-2.3%, Mg: 0.08-0.1%, Si: 0.01-0.03%, Nb: 0.01-0.02%, V: 0.01-0.03%, P: 0.03-0.04%, and the balance being Cu.

[0013] The application provides a preparation method of a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance.

[0014] The Cu-Fe alloy material of the application has a low Fe content, and the main strengthening source is work hardening. Work hardening is a strengthening mechanism for improving the strength of a material by introducing a large number of dislocations through plastic deformation. The preparation method of the application uses the rapid processing effect of electric pulses and combines with the water quenching process to quickly fix the organizational state of work hardening, so that the dislocation density and organizational distortion state are retained. The benefits mainly include: (1) improving the strength and hardness of the alloy and significantly enhancing the plastic deformation resistance; (2) providing a high strength basis in the processing state to facilitate the performance optimization in subsequent applications; (3) improving the wear resistance and fatigue resistance, so that the alloy is more suitable for use under complex working conditions.

[0015] The application forms a preparation process significantly different from the prior art by the whole electric pulse treatment combined with water quenching and component optimization. The method retains the work hardening effect and improves the strength and hardness on the one hand, and optimizes the distribution of the strengthening phase by introducing Mg and other trace elements and controlling Fe precipitation, thereby avoiding the coarsening problem in the traditional process, so as to realize the efficient, energy-saving and excellent performance of the Cu-Fe alloy preparation.

[0016] In the present application, the first two times of electric pulse treatment can make the Fe element fully dissolved in the Cu matrix before cold rolling, and can make the trace elements of Mg, Si, V, P and Nb more uniformly distributed in the Cu matrix. During the third and fourth times of electric pulse treatment, high energy input can stimulate more α-Fe phase precipitation sites, so that the α-Fe phase can be more dispersed and fully precipitated. At this time, the more uniformly distributed Mg, Si, V, P and Nb elements can more fully interact with the α-Fe phase, thereby better inhibiting the high-temperature coarsening of the α-Fe phase.

[0017] In addition, during the electric pulse treatment, due to the instantaneous high energy input, significant thermal vibration effects occur inside the material, and the grains may grow rapidly at high temperature. Rapid cooling through water quenching can effectively freeze the grain boundary migration behavior, inhibit grain growth, and well control the final grain size, thereby improving the strength and toughness of the material, and locking the non-equilibrium state structure. During the electric pulse treatment, the Cu matrix and Fe element in the alloy are in a non-equilibrium dissolution or precipitation state, and water quenching can quickly "fix" this organizational state, providing an ideal initial organizational basis for the final precipitation, and reducing internal stress and segregation.

[0018] Preferably, the melting is non-vacuum melting.

[0019] Preferably, the melting process is as follows: pure copper, Cu-Fe intermediate alloy, Cu-V intermediate alloy, Cu-Nb intermediate alloy, pure Si, pure Mg and pure P are prepared according to the designed proportion, the pure copper is first melted, then the temperature is raised to 1200-1300℃, the Cu-Fe intermediate alloy is added in 2-3 batches, and after 2-3 min of heat preservation, stirring is performed for 30-60 s, then the Cu-V intermediate alloy, Cu-Nb intermediate alloy, pure Si, pure Mg and pure P are added, after 1-2 min of heat preservation, the temperature is lowered to 1150-1250℃ under stirring, and then casting is performed. Through the above feeding mode, the alloy liquid obtained by melting can be most uniform.

[0020] Preferably, the parameters of the first electric pulse treatment are as follows: the frequency is 3000-5000 Hz, the pulse width is 500-3000 μs, the amplitude of the current density is 4000-8000 A / mm 2 , the effective current density is 550-2500 A / mm 2 , the highest temperature of the first electric pulse treatment is 750-950℃, and the time of the first electric pulse treatment is 2-5 min. In actual operation, the ingot surface defects are removed and corrected after the first electric pulse treatment, so as to ensure that the surface of the ingot is free of oxidation layer, shrinkage cavity and internal hole, etc.

[0021] In the present application, after obtaining the ingot, the ingot is subjected to a first electric pulse treatment for a short time, the diffusion process of the Fe element in the Cu matrix is accelerated through the instantaneous high-energy input and rapid heating effect of the electric pulse, the element segregation is quickly eliminated, the element concentration gradient near the grain boundary is reduced by the electric field effect of the electric pulse, the uniform distribution of the alloy composition is promoted, the local defects and internal stress in the as-cast structure are eliminated, the overall structural uniformity of the alloy is improved, and the phenomenon of grain coarsening is avoided.

[0022] In a preferred embodiment, the hot rolling process is as follows: first, the material is kept at 850-950 DEG C for 0.5-1 h, then hot rolling is performed, the single pass deformation amount of the hot rolling is controlled to be 20-40%, preferably 35-40%, the total deformation amount is 50-90%, and the total pass number is ≤3.

[0023] In the present application, by controlling the total pass number to be ≤3, i.e., using a larger reduction amount during single pass processing, dislocations and distortion structures can be introduced to the material interior to a greater extent, the material density is increased, the work hardening effect is improved as much as possible, and after hot rolling, the work hardening effect is retained by immediate water quenching.

[0024] In addition, controlling the reduction amount and the total pass number within the scope of the present application has the following advantages: (1) improving production efficiency: reducing the number of passes, shortening the processing time, reducing equipment wear and energy consumption, thereby significantly reducing manufacturing costs. (2) reducing material thermal accumulation effect: reducing the risk of grain growth and oxidation loss, reducing the performance degradation of the material at high temperature, and improving the material yield. (3) optimizing material performance: reducing the number of passes helps to improve the uniformity of the structure, reduce residual stress, and improve the strength, toughness and dimensional stability of the material. (4) supporting advanced processes: combining controlled rolling and controlled cooling technologies, reducing the number of passes optimizes the process flow, improves product quality, and reduces subsequent processing requirements. (5) energy saving and emission reduction: reducing the number of heating times can reduce energy consumption and carbon emissions, meeting the requirements of green manufacturing.

[0025] In a preferred embodiment, the thickness of the hot rolled blank obtained after hot rolling is ≥10 mm. In the present application, the thickness of the hot rolled blank needs to be controlled to be greater than 10 mm, and a hot rolled blank that is too thin cannot provide sufficient deformation amount for subsequent rolling deformation, and cannot further improve the work hardening effect.

[0026] In a preferred embodiment, the parameters of the second electric pulse treatment are as follows: the frequency is 2000-5000 Hz, the pulse width is 500-3000 μs, and the amplitude of the current density is 3000-8000 A / mm 2 , and the effective current density is 500-2000 A / mm 2The highest temperature of the second electric pulse treatment is 700-900℃, and the time of the second electric pulse treatment is 20s-5min. The Cu-Fe alloy hot-rolled blank after the second electric pulse treatment is water quenched, and then the surface oxide layer is removed by machining.

[0027] The second electric pulse treatment further makes the Fe element quickly and fully dissolve in the Cu matrix, and makes the Mg, Si, V, P, Nb trace elements more uniformly distributed in the Cu matrix. Compared with the traditional heat treatment, the electric pulse treatment can be carried out at a lower temperature, reduces the adverse effects of high-temperature treatment on the microstructure of the alloy, and through the rapid heating and cooling of the second electric pulse treatment, the grain growth is inhibited on the basis of ensuring the sufficient dissolution of the Fe element, the fine grain structure of the matrix is maintained, and the comprehensive performance of the alloy is further improved.

[0028] In a preferred embodiment, the single pass deformation of the first cold rolling is 10-20%, the total deformation is 50-90%, and the pass number is ≤6.

[0029] In a preferred embodiment, the thickness of the blank obtained after the first cold rolling is ≥1mm. Controlling the thickness after the first cold rolling within this range can further provide sufficient deformation allowance for the second cold rolling and improve the work hardening effect.

[0030] In a preferred embodiment, the parameters of the third electric pulse treatment are: the frequency is 2000-5000Hz, the pulse width is 500-3000μs, the amplitude of the current density is 1500-5000A / mm 2 , the effective current density is 500-1500A / mm 2 ; the temperature of the third electric pulse treatment is 550-650℃, and the time of the third electric pulse treatment is 20s-60s.

[0031] In a preferred embodiment, the single pass deformation of the second cold rolling is 10-15%, the total deformation is 50-90%, and the total pass number is ≤7.

[0032] In a preferred embodiment, the parameters of the fourth electric pulse treatment are: the frequency is 2000-4000Hz, the pulse width is 500-3000μs, the amplitude of the current density is 1500-4000A / mm 2 , the effective current density is 500-1200A / mm 2 ; the temperature of the fourth electric pulse treatment is 400-500℃, and the time of the fourth electric pulse treatment is 20s-60s.

[0033] Due to the short treatment time, the surface oxidation is small, and a clean surface can be obtained only by pickling.

[0034] In the present application, after the first cold rolling and the second cold rolling, the third and fourth electric pulse treatments are carried out respectively, and finally the fine and dispersed α-Fe phase is precipitated.

[0035] The inventors found that, due to the introduction of Mg and other micro-alloying elements in the present application, only by adopting the third and fourth electric pulse treatments, the fine and dispersed α-Fe phase can be obtained, which cannot be obtained by traditional heat treatment, and the main reasons are as follows:

[0036] 1. Synergistic effect of dynamic grain boundary motion and strengthening phase refinement

[0037] The transient high temperature and electric field effect in the electric pulse treatment can induce dynamic grain boundary motion. This grain boundary migration can be realized at a lower temperature, which helps to refine the grains and avoid the excessive coarsening of Fe phase at the grain boundary. After the introduction of Mg and other micro-alloying elements, the micro-alloying atoms tend to segregate at the grain boundary, further enhancing the inhibition effect on the grain boundary motion, thereby inhibiting the coarsening of Fe phase. The effect of this dynamic regulation cannot be achieved by traditional heat treatment.

[0038] 2. Activation and distribution adjustment of Mg and other micro-alloying elements induced by electric pulse

[0039] The high-density current in the electric pulse treatment can activate the micro-alloying atoms and accelerate their diffusion and uniform distribution in the Cu matrix. The segregation of micro-alloying elements inhibits the enrichment of Fe elements at the grain boundary and subgrain boundary, effectively limiting the growth and coarsening of Fe phase in subsequent treatment. In traditional heat treatment, the diffusion rate of micro-alloying atoms is slow, and similar effects cannot be achieved in a short time.

[0040] 3. Morphology control of precipitated phase

[0041] The electric pulse treatment changes the precipitation path of Fe phase through "transient heat-cooling cycle". In the third and fourth electric pulse treatments, the precipitation of strengthening phase tends to exist in the form of fine particles or dispersion, rather than growing into plates or forming coarse dendritic Fe phase. After the introduction of Mg and other micro-alloying atoms, the atoms form metastable complex phases with Fe, further reducing the surface energy of the strengthening phase, inhibiting the coarsening of Fe phase, and promoting the uniform distribution of precipitated particles. Traditional heat treatment often lacks such control ability of precipitation morphology.

[0042] 4. Electric field effect and diffusion barrier reduction

[0043] The electric field effect of the electric pulse reduces the diffusion barrier of Fe atoms, accelerating the movement of Fe elements in the Cu matrix. At the same time, the electric pulse enhances the interaction between the micro-alloying atoms and Fe, enabling them to more effectively participate in the regulation of the Fe precipitation process. This effect is particularly evident after repeated cold rolling-electric pulse treatment, because the high-density dislocations produced by cold rolling provide channels for the diffusion of micro-alloying atoms such as Mg and Fe atoms, and the electric pulse further activates the diffusion process. This effect is difficult to achieve in traditional heat treatment, because traditional heat treatment is limited by the thermal diffusion mechanism and has a slow rate.

[0044] Principles and advantages

[0045] The present application provides a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance. The present application uses a lower content of Fe element than the prior art, which greatly reduces the scattering effect of impurity atoms on electrons, and is more conducive to improving the electrical conductivity of Cu-Fe alloy, promoting the application of Cu-Fe alloy in the field of electronic information, transportation, etc. On the other hand, due to the lower Fe content of the Cu-Fe alloy, the main strengthening effect comes from work hardening, and the alpha-Fe phase precipitated by aging will rapidly coarsen at high temperature, weakening the interaction between the dislocation substructure produced by processing and the precipitated phase, thereby greatly reducing the strength and heat resistance of the alloy; Based on this, on the one hand, by adding Mg element, the Mg element can effectively delay the precipitation phase change of alpha-Fe phase and inhibit the rapid coarsening of alpha-Fe phase at high temperature, and at the same time, the Mg element itself can form stable magnesium compounds at high temperature, improving the thermal stability and softening resistance of the material; On the other hand, by adding trace elements Si, V, P, Nb, they can form heat-resistant primary second phases such as Fe3Si, Fe3P, etc. with Fe phase, and by adding more trace elements, multiple-scale heat-resistant second phases are formed in the Cu-Fe alloy, and appropriate trace elements can further refine the grains, inhibit grain growth, and improve the mechanical properties of the material, thereby synergistically enhancing the work hardening effect, forming a high-strength high-conductivity heat-resistant Cu-Fe alloy under the action of multiple strengthening mechanisms.

[0046] The preparation method provided by the present application utilizes the rapid processing effect of electric pulse, combined with water quenching process, to quickly fix the work-hardened organizational state, so that the dislocation density and organizational distortion state can be retained. The benefits mainly include: (1) improving the strength and hardness of the alloy, and significantly enhancing the plastic deformation resistance; (2) providing a high-strength basis in the processing state, facilitating performance optimization in subsequent applications; (3) improving wear resistance and fatigue resistance, making the alloy more suitable for use under complex working conditions.

[0047] In summary, the application realizes the comprehensive improvement of the performance of Cu-Fe alloy by combining alloy composition optimization, whole-process electric pulse treatment in the preparation process and water quenching treatment. The application not only improves the strength, toughness and high-temperature stability of the alloy, but also improves the uniformity and softening resistance of the structure, and has short preparation cycle, short electric pulse treatment time and high efficiency, thereby providing an efficient, energy-saving and adjustable innovative scheme for the research and development of high-performance copper-based alloy. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0049] Figure 1 The solid solution ingot of the high-strength, high-conductivity and high-heat-resistant Cu-Fe alloy material after machining and removing the oxidation layer for the embodiment 1 of the application.

[0050] Figure 2 The finished product obtained by pickling after secondary aging in the preparation process of the alloy of the embodiment 1 of the application.

[0051] Figure 3 TEM observation after high-energy electric pulse aging in the preparation process of the alloy of the embodiment 1 of the application.

[0052] Figure 4 TEM observation after high-energy electric pulse aging in the preparation process of the alloy of the comparative example 1 of the application.

[0053] Figure 5 Metallographic structure after high-energy electric pulse solution treatment in the preparation process of the alloy of the embodiment 2 of the application.

[0054] Figure 6 Metallographic structure after high-energy electric pulse intermediate annealing treatment in the preparation process of the alloy of the embodiment 2 of the application.

[0055] Figure 7 Metallographic structure after furnace solution treatment in the preparation process of the alloy of the comparative example 4 of the application.

[0056] Figure 8 Metallographic structure after furnace intermediate annealing treatment in the preparation process of the alloy of the comparative example 5 of the application.

[0057] Figure 9 Metallographic structure after high-energy electric pulse intermediate annealing treatment in the preparation process of the alloy of the comparative example 6 of the application. DETAILED DESCRIPTION

[0058] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the description examples.

[0059] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the concept of the present application, therefore the present application is not limited to the specific examples disclosed below.

[0060] Secondly, "one embodiment" or "embodiment" referred to herein means that a specific feature, structure or characteristic can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent of or mutually exclusive with other embodiments.

[0061] Example 1

[0062] Example 1 prepares a Cu-Fe alloy material with high strength, high conductivity and high heat resistance. The material composition includes Fe: 2.3%, Mg: 0.1%, P: 0.03%, Si: 0.03%, Nb: 0.01%, V: 0.01% by mass, and the balance is Cu.

[0063] The preparation method of the high-strength, high-conductivity and high-heat-resistant Cu-Fe alloy material selected in Example 1, the preparation process includes:

[0064] Step (1): non-vacuum melting is carried out by using a medium frequency induction melting furnace to obtain an ingot, and the melting additive raw materials include electrolytic copper (99.95wt.%), Cu-10wt.% Fe intermediate alloy, Cu-5wt.% V intermediate alloy, Cu-5wt.% Nb intermediate alloy, pure Si (99.95wt.%), pure Mg (99.95wt.%), pure P (99.95wt.%), and the raw materials, crucible and mold are dried before melting. The pure copper is melted first (1083℃), Cu-Fe intermediate alloy is added at a melt temperature of 1250℃, and is added in 3 batches, and is stirred for 45 s after 2.5 min of heat preservation; then Cu-Nb intermediate alloy, Cu-V intermediate alloy, pure Si, pure Mg and pure P are added, and the power of the induction furnace is reduced (the process lasts for 60 s) while stirring for 1.5 min of heat preservation, so that the melt temperature is reduced to 1200℃, and then casting is started.

[0065] Step (2) is the first electric pulse treatment of the ingot. The parameters input to the Cu-Fe alloy cold-rolled strip during the high-energy electric pulse aging treatment are: a frequency of 3000 Hz, a pulse width of 1000 μs, an amplitude of the current density of 7000 A / mm 2 , an effective current density of 2000 A / mm 2 ; the first electric pulse treatment is performed at a temperature of 920℃ for 4 min, and then water quenching is performed after the first electric pulse treatment. Then, the ingot surface defects are removed and corrected by machining to ensure that the ingot surface is free of oxide layers, shrinkage holes and inner holes, etc.

[0066] Step (3) is a hot rolling process. The holding temperature before hot rolling is 900℃, the holding time is 0.5 h, the single hot rolling reduction is about 40%, the cumulative hot rolling deformation is about 80%, and the hot rolling is completed in 2 passes. After hot rolling, water quenching is performed, the surface oxide layer is removed by machining, and the thickness of the hot-rolled blank is about 16.5 mm.

[0067] Step (4) is the second electric pulse treatment of the ingot. The parameters input to the Cu-Fe alloy hot-rolled blank during the second electric pulse treatment are: a frequency of 3000 Hz, a pulse width of 2000 μs, an amplitude of the current density of 6500 A / mm 2 , an effective current density of 1800 A / mm 2 ; the second electric pulse treatment is performed at a maximum temperature of 850℃ for 4 min; and the Cu-Fe alloy hot-rolled blank after the second electric pulse treatment is water quenched.

[0068] Step (5) is a first cold rolling of the strip after the second electric pulse treatment. The single deformation of the first cold rolling is 15-20%, the cumulative total deformation is about 90%, and the first cold rolling is completed in 5 passes. The thickness of the strip after the first cold rolling is about 1.6 mm.

[0069] Step (6) is a third electric pulse treatment of the strip after the first cold rolling. The parameters input to the Cu-Fe alloy cold-rolled strip during the third electric pulse treatment are: a frequency of 3500 Hz, a pulse width of 2000 μs, an amplitude of the current density of 3000 A / mm 2 , an effective current density of 1000 A / mm 2 ; the third electric pulse treatment is performed at a temperature of 600℃ for 40 s.

[0070] Step (7) is a second cold rolling of the strip after the third electric pulse treatment. The single deformation of the second cold rolling is about 10-15%, the cumulative total deformation is about 88%, and the second cold rolling is completed in 6 passes. The thickness of the strip after the cold rolling is about 0.2 mm.

[0071] Step (8) is a fourth electric pulse treatment of the strip after the second cold rolling. The parameters input to the Cu-Fe alloy cold-rolled strip during the fourth electric pulse treatment are: a frequency of 3000 Hz, a pulse width of 2500 μs, and an amplitude of the current density of 2500 A / mm 2 , an effective current density of 800 A / mm 2 ; the fourth electric pulse treatment temperature is 450℃, the fourth electric pulse treatment time is 40 s, and then the finished product with a clean surface is obtained through pickling.

[0072] Comparative Example 1

[0073] Comparative Example 1 prepared a Cu-Fe alloy material, the material components include Fe: 2.3%, Mg: 0.02%, P: 0.03%, Si: 0.03%, Nb: 0.01%, V: 0.01% by mass, and the balance is Cu.

[0074] The subsequent preparation process is the same as that of Example 1.

[0075] Figure 5 TEM observation results after the fourth electric pulse treatment in the preparation process of Comparative Example 1.

[0076] Comparative Example 2

[0077] Comparative Example 2 prepared a Cu-Fe alloy material, the material components include Fe: 2.3%, Mg: 0.15%, P: 0.03%, Si: 0.4%, Nb: 0.01%, V: 0.01% by mass, and the balance is Cu.

[0078] The subsequent preparation process is the same as that of Example 1.

[0079] Comparative Example 3

[0080] Comparative Example 3 prepared a Cu-Fe alloy material, the material components include Fe: 2.3%, Mg: 0.15%, P: 0.03%, Si: 0.05%, Nb: 0.8%, V: 0.01% by mass, and the balance is Cu.

[0081] The subsequent preparation process is the same as that of Example 1.

[0082] Table 1 is a comparison of the properties of Cu-Fe alloys in the solid solution state and after treatment according to Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3. The Cu-Fe alloy treated according to the process of Example 1 has the highest hardness and tensile strength of all the samples. Although the elongation and electrical conductivity of Comparative Example 1 are superior to those of Example 1, the hardness, tensile strength and softening temperature of Comparative Example 1 are much lower than those of Example 1, and do not fall within the category of high-strength and high-heat-resistant alloys. In addition, due to the excessive addition of elements, the hardness, tensile strength and softening temperature of Comparative Examples 2 and 3 are not superior to those of Example 1, but the elongation and electrical conductivity are greatly reduced, and the overall performance is still inferior to that of Example 1.

[0083]

[0084] Figure 1 A solid solution ingot of the high-strength, high-conductivity and high-heat-resistant Cu-Fe alloy material prepared in Example 1 of the present application after machining to remove the oxide layer.

[0085] Figure 2 A finished product obtained by pickling after the fourth electric pulse treatment during the preparation of the alloy of Example 1 of the present application.

[0086] Figure 3 A TEM observation result after high-energy electric pulse aging during the preparation of the alloy of Example 1 of the present application. The size and distribution of the α-Fe phase, which is the main strengthening precipitate phase in the alloy, are counted here. The phenomenon of subgrain boundaries formed by dislocation wall connection and merging can be observed in the selected area, and when the subgrain boundaries migrate here, they must be pinned by the α-Fe phase. It can be seen that the second phase in the finished state is in a fine and dispersed distribution, with an average size of 20.68 nm, effectively hindering the migration of dislocations and grain boundaries during the softening process of the material.

[0087] Figure 4 A TEM observation result after the fourth electric pulse treatment during the preparation of the alloy of Comparative Example 1 of the present application. The same phenomenon of subgrain boundaries formed by dislocation wall connection and merging can be observed in the selected area. Figure 3 In comparison with Figure 4 The difference in the size and distribution of the α-Fe phase during the formation of the grain boundaries is visually displayed. Compared with Example 1, the size of the second phase in Comparative Example 1 is obviously larger, and the density of the phase distribution is also not as good as that of Example 1. Due to the appropriate addition of Mg element, the α-Fe phase of the Cu-Fe alloy of Example 1 can remain in a finer and more dispersed state at high temperatures, which is beneficial to resisting softening caused by recrystallization of the copper matrix, improving the high-temperature softening resistance of the alloy, and retaining more work hardening effect during aging, thereby improving the strength.

[0088] Example 2

[0089] Example 2: A Cu-Fe alloy material with high strength, high conductivity and high heat resistance was prepared, and the material composition included Fe: 2.0%, Mg: 0.08%, P: 0.03%, Si: 0.01%, Nb: 0.01%, V: 0.03% by mass, and the balance was Cu.

[0090] Example 2: The preparation method of the Cu-Fe alloy material with high strength, high conductivity and high heat resistance was as follows:

[0091] Step (1): A non-vacuum melting furnace was used to obtain an ingot, and the melting added raw materials included electrolytic copper (99.95wt.%), Cu-10wt.% Fe intermediate alloy, Cu-5wt.% V intermediate alloy, Cu-5wt.% Nb intermediate alloy, pure Si (99.95wt.%), pure Mg (99.95wt.%), and pure P (99.95wt.%). The raw materials, crucible, and mold were dried before melting. The pure copper was first melted (1083℃), and the Cu-Fe intermediate alloy was added at a melt temperature of 1270℃, and was added in two batches. After 2.5 minutes of insulation, stirring was performed. Then, the Cu-Nb intermediate alloy, Cu-V intermediate alloy, pure Si, pure Mg, and pure P were added, and after 1.5 minutes of continuous insulation, the stirring was performed while the induction furnace power was reduced (the process lasted for 60 s), so that the melt temperature was reduced to 1200℃ to start casting.

[0092] Step (2): The ingot was subjected to a first electric pulse treatment. The parameters input to the Cu-Fe alloy cold-rolled strip added electric region section during the first electric pulse treatment were as follows: the frequency was 4000 Hz, the pulse width was 1500 μs, the amplitude of the current density was 6000 A / mm 2 , and the effective current density was 1800 A / mm 2 . The temperature of the first electric pulse treatment was 910℃, the time of the first electric pulse treatment was 3 min, and after the first electric pulse treatment, water quenching was performed, and then the ingot surface defects were removed and corrected by machining, so that the ingot surface was free of oxidation layer, shrinkage cavity, and internal hole, etc.

[0093] Step (3): The homogenized blank was subjected to hot rolling breakdown treatment. The temperature before hot rolling was 870℃, the insulation time was 1 h, the single hot rolling reduction was about 35%, the cumulative hot rolling deformation was about 70%, and the hot rolling was completed in 2 passes. After hot rolling, water quenching was performed, the surface oxidation layer was removed by machining, and the thickness of the hot rolled blank was about 20.5 mm.

[0094] Step (4) is a second electric pulse treatment of the ingot. The parameters input to the Cu-Fe alloy hot-rolled blank during the second electric pulse treatment are: a frequency of 3500 Hz, a pulse width of 2500 μs, an amplitude of the current density of 6000 A / mm 2 , an effective current density of 1600 A / mm 2 ; the highest temperature of the second electric pulse treatment is 830℃, the time of the second electric pulse treatment is 3.5 min; and the Cu-Fe alloy hot-rolled blank after the second electric pulse treatment is water quenched.

[0095] Step (5) is a first cold rolling of the strip after the second electric pulse treatment. The single deformation of the first cold rolling is 15-20%, and the total cumulative deformation is about 80%, and the first cold rolling is completed in 4 passes. The thickness of the strip after the first cold rolling is about 4.1 mm.

[0096] Step (6) is a third electric pulse treatment of the strip after the first cold rolling. The parameters input to the Cu-Fe alloy cold-rolled strip during the third electric pulse treatment are: a frequency of 4000 Hz, a pulse width of 1000 μs, an amplitude of the current density of 2500 A / mm 2 , an effective current density of 900 A / mm 2 ; the temperature of the third electric pulse treatment is 580℃, and the time of the third electric pulse treatment is 30 s.

[0097] Step (7) is a second cold rolling of the strip after the third electric pulse treatment. The single deformation of the second cold rolling is about 10-15%, and the total cumulative deformation is about 80%, and the second cold rolling is completed in 6 passes. The thickness of the strip after the cold rolling is about 0.8 mm.

[0098] Step (8) is a fourth electric pulse treatment of the strip after the second cold rolling. The parameters input to the Cu-Fe alloy cold-rolled strip during the fourth electric pulse treatment are: a frequency of 2500 Hz, a pulse width of 1500 μs, an amplitude of the current density of 3000 A / mm 2 , an effective current density of 900 A / mm 2 ; the temperature of the fourth electric pulse treatment is 480℃, and the time of the fourth electric pulse treatment is 30 s, and then the finished product with a clean surface is obtained through pickling.

[0099] Comparative Example 4

[0100] The Cu-Fe alloy material prepared in Comparative Example 4 has the same material composition as that of Example 2.

[0101] The other preparation method of the Cu-Fe alloy material selected in Comparative Example 4 is the same as that in Example 2, only the second electric pulse blowing is changed to heating furnace treatment, the temperature is still 830°C, and the time is 60 min.

[0102] Comparative Example 5

[0103] The Cu-Fe alloy material prepared in Comparative Example 5 has the same material composition as that in Example 2.

[0104] The other preparation method of the Cu-Fe alloy material selected in Comparative Example 5 is the same as that in Example 2, only the third electric pulse treatment is changed to heating furnace treatment, the temperature is still 580°C, and the time is 60 min.

[0105] Comparative Example 6

[0106] The Cu-Fe alloy material prepared in Comparative Example 6 has the same material composition as that in Example 2.

[0107] The other preparation method of the Cu-Fe alloy material selected in Comparative Example 6 is the same as that in Example 2, only the fourth electric pulse treatment is changed to heating furnace treatment, the temperature is still 480°C, and the time is 60 min.

[0108] Comparative Example 7

[0109] The Cu-Fe alloy material prepared in Comparative Example 7 has the same material composition as that in Example 2.

[0110] The other preparation method of the Cu-Fe alloy material selected in Comparative Example 7 is the same as that in Example 2, only the effective current density of the third electric pulse treatment is changed to 1600 A / mm 2 At this time, the alloy surface temperature is 820°C.

[0111] Comparative Example 8

[0112] The other conditions are the same as those in Example 2, only the hot rolling is followed by air cooling.

[0113] Table 1 is a comparison of the properties of the Cu-Fe alloy in the solid solution state and after treatment according to Example 2, Comparative Example 4, Comparative Example 5, Comparative Example 6, Comparative Example 7. The Cu-Fe alloy treated according to the process of Example 2 has the highest hardness, tensile strength and softening temperature of all the samples. Although the elongation and electrical conductivity of individual comparative examples are better than those of Example 2, the hardness, tensile strength and softening temperature of these comparative examples are all reduced to varying degrees and are much lower than those of Example 2, and do not belong to the category of high-strength and high-heat-resistant alloys.

[0114]

[0115] Figure 5The microstructure of the alloy after the second electric pulse treatment during the preparation of the alloy of Example 2 of the present application. It can be seen that even after the electric pulse treatment at a higher temperature, the grain size of the alloy under the process of Example 2 is not coarse, and the average grain size is 20.6 μm, which provides excellent initial organizational conditions for subsequent processing.

[0116] Figure 6 The microstructure of the alloy after the third electric pulse treatment during the preparation of the alloy of Example 2 of the present application. The picture shows that the intermediate annealed alloy substrate grains are very fine and uniform, with an average grain size of 8.6 μm, maintaining a fine grain structure of the substrate and further improving the comprehensive performance of the alloy.

[0117] Figure 7 The microstructure of the alloy after the heating furnace treatment during the preparation of the alloy of Comparative Example 4 of the present application. It can be seen that due to the long time required for the solution of the alloy under the process of Comparative Example 4, the grain size of the alloy is very coarse, with an average grain size of 59.7 μm, and the hot rolling structure is basically completely eliminated.

[0118] Figure 8 The microstructure of the alloy after the heating furnace treatment during the preparation of the alloy of Comparative Example 5 of the present application. It can be seen that the alloy has reached a complete recrystallization state at this time, but due to the long treatment time, the grains have grown, with an average grain size of about 18.3 μm. The coarsened intermediate annealed grains reduce the comprehensive performance of the alloy and eliminate more of the work hardening effect after the first cold rolling.

[0119] Figure 9 The microstructure of the alloy after the third electric pulse treatment during the preparation of the alloy of Comparative Example 6 of the present application. Due to the excessively high effective current density of the high-energy electric pulse, the annealing temperature is too high, and even though the annealing time is short, the high-temperature coarsening rate of the grains is still extremely fast under the driving of the electric effect, with an average grain size of about 49.5 μm, which fails to provide favorable conditions for the subsequent processing of a fine and uniform grain structure.

[0120] As can be seen from Example 1, Example 2, and Comparative Examples 1, 2, 3, 4, 5, 6, and 7, the Cu-Fe alloy material prepared by the present application has the characteristics of high hardness, high strength, high electrical conductivity, and high softening temperature; the various process parameters and conditions in the present application have a synergistic effect, and when a parameter or a process link is not within the protection scope of the present application, the performance of the obtained product is far inferior to that of the present application.

[0121] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A method for preparing a Cu-Fe alloy material that combines high strength, high electrical conductivity, and high heat resistance, characterized in that: The Cu-Fe alloy material is obtained by the following steps: smelting to obtain an ingot, performing first electric pulse treatment on the ingot, then performing hot rolling, performing second electric pulse treatment after the hot rolling, and then sequentially performing one-time cold rolling treatment, third electric pulse treatment, two-time cold rolling treatment, and fourth electric pulse treatment; the cooling mode after the first electric pulse treatment, the hot rolling, and the second electric pulse treatment is water quenching. The parameters of the third electric pulse treatment are: frequency 2000-5000 Hz, pulse width 500-3000 μs, amplitude of current density 1500-5000 A / mm 2 , effective current density 500-1500 A / mm 2 ; the temperature of the third electric pulse treatment is 550-650℃, and the time of the third electric pulse treatment is 20 s-60 s; The Cu-Fe alloy material comprises the following components in percentage by mass: Fe: 0.8-3%, Mg: 0.05-0.2%, Si: 0-0.1%, Nb: 0-0.2%, V: 0-0.1%, P: 0-0.1%, and the balance being Cu, and the total mass percentage of Si, V, P, and Nb is less than 0.2%.

2. The method for preparing a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance according to claim 1, characterized in that: The smelting process comprises the following steps: preparing pure copper, Cu-Fe intermediate alloy, Cu-V intermediate alloy, Cu-Nb intermediate alloy, pure Si, pure Mg, and pure P according to the designed proportions, melting the pure copper, heating to 1200-1300 DEG C, adding the Cu-Fe intermediate alloy in 2-3 batches, stirring for 30-60 s after 2-3 min of heat preservation, then adding the Cu-V intermediate alloy, Cu-Nb intermediate alloy, pure Si, pure Mg, and pure P, and stirring while cooling to 1150-1250 DEG C after 1-2 min of heat preservation, and then casting.

3. The method for preparing a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance according to claim 1, characterized in that: The parameters of the first electric pulse treatment are: frequency 3000-5000 Hz, pulse width 500-3000 μs, amplitude of current density 4000-8000 A / mm 2 , effective current density 550-2500 A / mm 2 ; the highest temperature of the first electric pulse treatment is 750-950℃, and the time of the first electric pulse treatment is 2-5 min.

4. The method for preparing a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance according to claim 1, characterized in that: The hot rolling process comprises the following steps: heat preservation at 850-950 DEG C for 0.5-1 h, then hot rolling, controlling the single-pass deformation of the hot rolling to be 20-40%, the total deformation to be 50-90%, and the total number of passes to be less than or equal to 3. The thickness of the hot-rolled blank obtained after the hot rolling is greater than or equal to 10 mm.

5. The method for preparing a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance according to claim 1, characterized in that: The parameters of the second electric pulse treatment are: frequency 2000-5000 Hz, pulse width 500-3000 μs, amplitude of current density 3000-8000 A / mm 2 , effective current density 500-2000 A / mm 2 ; the highest temperature of the second electric pulse treatment is 700-900℃, and the time of the second electric pulse treatment is 20 s-5 min.

6. The method for preparing a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance according to claim 1, characterized in that: The single-pass deformation of the one-time cold rolling is 10-20%, the total deformation is 50-90%, and the number of passes is less than or equal to 6. The thickness of the blank obtained after the one-time cold rolling is greater than or equal to 1 mm.

7. The method for preparing a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance according to claim 1, characterized in that: The single-pass deformation of the two-time cold rolling is 10-15%, the total deformation is 50-90%, and the total number of passes is less than or equal to 7.

8. The method for preparing a Cu-Fe alloy material with high strength, high electrical conductivity and high heat resistance according to claim 1, characterized in that: The fourth electric pulse treatment has the parameters of frequency of 2000-4000 Hz, pulse width of 500-3000 μs, amplitude of current density of 1500-4000 A / mm 2 , effective current density of 500-1200 A / mm 2 ; the fourth electric pulse treatment has the temperature range of 400-500℃, and the fourth electric pulse treatment has the time of 20 s-60 s.

9. The method for preparing Cu-Fe alloy material with high strength, high conductivity and high heat resistance according to any one of claims 1-8, characterized in that: The Cu-Fe alloy material comprises the following components in percentage by mass: Fe: 1.5-3%, Mg: 0.05-0.15%, Si: 0-0.05%, Nb: 0-0.05%, V: 0-0.05%, P: 0-0.05%, and the balance being Cu.

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