CN114657410B - High-strength high-conductivity copper-iron alloy and preparation method thereof - Google Patents

Abstract

The present invention provides a high-strength and high-conductivity copper-iron alloy, which comprises the following components by weight percentage: Fe: 0.5-5.0 wt%, Si: 0.05-0.5wt%, Mg: 0.05-0.5wt%, Cr: ≤0.5 wt %, Zr: ≤ 0.15 wt %, Ca: ≤ 0.15 wt %, and the balance is Cu; the preparation method of the high-strength and high-conductivity copper-iron alloy includes the following steps: smelting the alloy components and casting to obtain a copper alloy ingot ; Perform homogenization annealing, the annealing temperature is 920-970°C, and the time is 24-48h; rolling-combined aging heat treatment, after rolling, the billet is subjected to combined aging heat treatment at 300-500°C, and the rolling-aging treatment process is repeated Two or more times, and finally the plate is subjected to stress relief annealing at 200-300° C. for 4-5 hours to prepare a high-strength and high-conductivity copper-iron alloy.

Description

A kind of high-strength and high-conductivity copper-iron alloy and preparation method thereof

technical field

The invention relates to the technical field of copper alloy processing, in particular to a high-strength and high-conductivity copper-iron alloy and a preparation method thereof.

Background technique

With the development of science and technology, copper alloys are widely used in more than 200 fields due to their excellent electrical and thermal conductivity, mechanical properties and processing properties. The correlation between copper alloy industry and other industries is as high as 90%. Copper-iron alloy not only has the excellent electrical conductivity, thermal conductivity, easy processing, antibacterial and other excellent properties of traditional copper alloys, but also has good electromagnetic shielding performance and relatively economical price. Therefore, copper-iron alloys have a wide range of application markets in many fields, especially in products such as integrated circuit lead frames, connector contacts, contact bridges and vacuum devices, Cu-Fe alloys have been widely used. Invention patent CN111424188A discloses the use of powder metallurgy to prepare copper-iron alloy plates. Due to the interface resistance between the powders and the compactness of the material itself, its mechanical and electrical properties cannot be optimized. Invention patent CN109022896A and invention patent CN111636010A disclose methods for preparing high-iron content, high-strength, and high-conductivity copper-iron alloys by casting, but due to the low solid solubility of iron in copper, the copper-iron alloys produced by smelting are very uneven, resulting in poor mechanical properties. worse.

Therefore, there is still a long way to go for the research and development of high-strength and high-conductivity copper-iron alloys.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a high-strength and high-conductivity copper-iron alloy, the tensile strength can reach 720-740MPa, and the electrical conductivity can reach 70-72% IACS, which realizes the balance of alloy strength and electrical conductivity.

In order to solve the above-mentioned problems, the technical scheme of the present invention is as follows:

A high-strength and high-conductivity copper-iron alloy, comprising the following components by weight percentage:

Fe: 0.5-5.0wt%, Si: 0.05-0.5wt%, Mg: 0.05-0.5wt%, Cr: ≤0.5wt%, Zr: ≤0.15wt%, Ca: ≤0.15wt%, the balance is Cu;

The preparation method of the high-strength and high-conductivity copper-iron alloy comprises the following steps:

In step S1, the elements required by the alloy are proportioned according to the design components, smelted in an inert gas, and cast to obtain a copper alloy ingot;

In step S2, the copper alloy ingot of step S1 is subjected to homogenization annealing, the annealing temperature is 920-970°C, and the time is 24-48h, and the homogenized ingot is cooled to 800-900°C;

Step S3, rolling-combined aging heat treatment, after rolling, the billet is subjected to combined aging heat treatment at 300-500 ° C, and the rolling-aging treatment process is repeated twice or more, and finally the sheet is subjected to 4 at 200-300 ° C. -5h stress relief annealing to prepare high-strength and high-conductivity copper-iron alloys;

The total deformation of the hot-rolled billet in the rolling process is 70-80%, and the total deformation of the cold-rolled is 70-90%.

Further, in step S1, electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy are selected as raw materials.

Further, the copper-magnesium master alloy is a Cu-30Mg master alloy, the copper-zirconium master alloy is a Cu-50Zr master alloy, and the copper-calcium master alloy is a Cu-50Ca master alloy.

Further, in step S3, the time of the last aging heat treatment of the combined aging heat treatment is 16-32 h, and the time of the remaining aging heat treatment is 1-2 h.

Further, in step S1, a vacuum smelting furnace is used for smelting, the vacuum degree is 10 ^-5 -10 ^-3 Pa, and the inert gas is high-purity argon; in the smelting process, a low-frequency magnetic field generated by an induction smelting furnace is used to melt the melt. Stir.

The present invention also provides a method for preparing a high-strength and high-conductivity copper-iron alloy, comprising the following steps:

In step S1, the elements required by the alloy are proportioned according to the design components, smelted in an inert gas, and cast to obtain a copper alloy ingot;

The alloy composition includes the following components by weight percentage:

Fe: 0.5-5.0wt%, Si: 0.05-0.5wt%, Mg: 0.05-0.5wt%, Cr: ≤0.5wt%, Zr: ≤0.15wt%, Ca: ≤0.15wt%, the balance is Cu;

In step S2, the copper alloy ingot of step S1 is subjected to homogenization annealing, the annealing temperature is 920-970°C, and the time is 24-48h, and the homogenized ingot is cooled to 800-900°C;

Step S3, rolling-combined aging heat treatment, after rolling, the billet is subjected to combined aging heat treatment at 200-500°C, and the rolling-aging treatment process is repeated twice or more, and finally the sheet is subjected to 4 at 200-300°C. -5h stress relief annealing to prepare high-strength and high-conductivity copper-iron alloys;

The total deformation of the hot-rolled billet in the rolling process is 70-80%, and the total deformation of the cold-rolled is 70-90%.

Further, in step S1, electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy are selected as raw materials; wherein the copper-magnesium master alloy is a master alloy of Cu-30Mg, The copper-zirconium master alloy is a Cu-50Zr master alloy, and the copper-calcium master alloy is a Cu-50Ca master alloy.

Further, in step S3, the time of the last aging heat treatment of the combined aging heat treatment is 16-32 h, and the time of the remaining aging heat treatment is 1-2 h.

Compared with the prior art, the high-strength and high-conductivity copper-iron alloy and the preparation method thereof provided by the present invention have beneficial effects as follows:

1. The high-strength and high-conductivity copper-iron alloy and its preparation method provided by the present invention utilize the microalloying of Mg, Si, Cr, Zr and Ca to promote the refinement of grains and the spheroidization of precipitated phases. The FeSi phase, CuCa phase and Cr phase precipitated in the alloy are pinned at the grain boundary, which improves the mechanical properties of the alloy. At the same time, the addition of microalloying elements also promoted the precipitation of primary iron phase during the process of casting and solidification, while the semi-grown CuCa phase beside the primary iron phase inhibited the growth of the primary iron phase. With the subsequent cold deformation processing, the micron-scale primary iron phase and the accompanying CuCa phase are broken into sub-micron-scale secondary phases, which are compared with the nano-scale iron phase and chromium phase precipitated through the combined deformation and aging heat treatment process from multiple scales. The mechanical properties of the alloy are strengthened, and the precipitated iron phase promotes the improvement of the electrical conductivity of the alloy. A small amount of Mg dissolved in the copper matrix can greatly improve the work hardening ability of the matrix on the basis of a small loss of electrical conductivity. The high-strength and high-conductivity copper-iron alloy of the present invention fully utilizes solid solution strengthening, precipitation strengthening, grain refinement strengthening and work hardening to achieve synergistic improvement of tensile strength and electrical conductivity, and its tensile strength can reach 720-750MPa, and its electrical conductivity can reach Achieving 70-72% IACS, achieving a balance of alloy strength and electrical conductivity.

2. The high-strength and high-conductivity copper-iron-based alloy provided by the present invention and the preparation method thereof, the alloy composition is designed with a relatively low content of iron, which greatly reduces the production difficulty of copper-iron alloys using ordinary smelting processes to prepare sheet, strip and foil, and reduces the The macroscopic defects of copper-iron alloy sheet, strip and foil are eliminated, and the alloy properties are more stable. The alloy preparation method of the invention has the advantages of simple and easy process, low cost, and is suitable for large-scale industrial production.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

Fig. 1 is the microstructure diagram of the as-cast state in Example 1 of the present invention;

Fig. 2 is the backscattered electron scanning electron microscope picture of finished plate in the embodiment of the present invention 1;

Fig. 3 is the tensile curve diagram of the finished sheet in Example 1 of the present invention;

4 is a microscopic topography diagram of a tensile fracture of a finished sheet in Example 1 of the present invention.

Detailed ways

In order for those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are further described below.

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

The high-strength and high-conductivity copper-iron-based alloy of the present invention includes the following components by weight percentage:

Fe: 0.5-5.0wt%, Si: 0.05-0.5wt%, Mg: 0.05-0.5wt%, Cr: ≤0.5wt%, Zr: ≤0.15wt%, Ca: ≤0.15wt%, the balance is Cu;

Each component selects electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy as raw materials, wherein copper-magnesium master alloy is preferably Cu-30Mg master alloy, copper-zirconium master alloy It is preferably a Cu-50Zr master alloy, and the copper-calcium master alloy is preferably a Cu-50Ca master alloy.

The preparation method of the high-strength and high-conductivity copper-iron alloy comprises the following steps:

In step S1, the elements required for the alloy are proportioned according to the design components, smelted in an inert gas, and cast to obtain a Cu-Fe-Mg-Si-Cr-Zr-Ca copper alloy ingot;

Specifically, a vacuum smelting furnace is used for smelting, the vacuum degree is 10 ^-5 -10 ^-3 Pa, and the inert gas is high-purity argon; the low-frequency magnetic field generated by the induction smelting furnace is used to stir the melt during the smelting process; smelting During the process, the furnace temperature is controlled at 1450-1500°C; the smelting temperature can be 1450°C, 1480°C or 1500°C, or other temperature values within this range;

After smelting, the molten copper alloy is cooled to 1250°C for casting, and the casting mold uses a graphite mold;

In step S2, the copper alloy ingot of step S1 is subjected to homogenization annealing, the annealing temperature is 920-970°C, and the time is 24-48h, and the homogenized ingot is cooled to 800-900°C;

Specifically, the annealing temperature can be 920°C, 930°C, 940°C, 950°C, 960°C or 970°C, or other temperature values within this range;

The annealing time can be 24h, 28h, 32h, 36h, 40h, 44h or 48h, or other time values within this range;

The temperature for cooling the ingot after homogenization can be 800°C, 820°C, 840°C, 860°C, 880°C or 900°C, or other temperature values within this range;

Step S3, rolling-combined aging heat treatment, after rolling, the billet is subjected to combined aging heat treatment at 300-500 ° C, and the rolling-aging treatment process is repeated twice or more, and finally the sheet is subjected to 4 at 200-300 ° C. -5h stress relief annealing to prepare high-strength and high-conductivity copper-iron alloys;

The total deformation of the hot-rolled billet in the rolling process is 70-80%, and the total deformation of the cold-rolled is 70-90%.

Specifically, the combined aging heat treatment temperature can be 300°C, 350°C, 400°C, 450°C or 500°C, or other temperature values within the temperature range;

Preferably, the last aging heat treatment time is 16-32h, such as 16h, 20h, 24h, 28h, or 32h, or other values within this range, and the remaining aging heat treatment time is 1-2h, such as 1h, 1.5h or 2h;

The stress relief annealing temperature can be 200°C, 220°C, 250°C, 260°C, 280°C or 300°C, or other temperature values within this range; the stress relief annealing time can be 4h, 4.5h or 5h, or for other time values within the range.

The high-strength and high-conductivity copper-iron alloy prepared by the invention is a double 70 series copper alloy with a tensile strength of over 700 MPa and a conductivity of over 70% IACS.

The high-strength and high-conductivity copper-iron-based alloy and the preparation method thereof of the present invention will be described in detail below through specific examples.

Example 1

A high-strength and high-conductivity copper-iron alloy, comprising the following components by weight percentage:

Fe: 2.5wt%, Si: 0.2wt%, Mg: 0.3wt%, Cr: 0.2wt%, Zr: 0.1wt%, Ca: 0.05wt%, the balance is Cu;

Electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy are selected as raw materials for each component; The alloy is a Cu-50Zr master alloy, and the copper-calcium master alloy is a Cu-50Ca master alloy.

The preparation method of the high-strength and high-conductivity copper-iron alloy of the present embodiment includes the following steps:

(1) Vacuum smelting: According to the above alloy components, the ingredients are added, the prepared raw materials are added to the graphite crucible, and the raw materials are melted in a vacuum induction furnace. During the process, high-purity argon gas is used for protection. During the smelting process, the low-frequency magnetic field is used to fully stir, control The furnace temperature is 1450-1500℃, and the vacuum degree is 10 ^-5 -10 ^-3 Pa;

(2) when the above-mentioned molten copper alloy temperature is cooled to 1250 ℃, cast, and the casting mold uses a graphite mold;

(3) Milling surface: Use a CNC milling machine to mill out the oxide layer and casting defects on the head and tail of the ingot and the surface;

(4) Homogenization annealing: place the ingot in a resistance furnace at 950° C. for homogenization annealing, and the homogenization time is 24 hours;

(5) Rolling-combined aging heat treatment: The ingot is subjected to three cold rolling and aging treatments, and the three cold rolling deformations are all greater than 80%. The first aging treatment temperature is 500 ° C, and the treatment time is 2 hours. The aging treatment temperature is 450 °C, the treatment time is 1 hour, the third aging treatment temperature is 350 °C, and the treatment time is 32 hours. The iron phase is further rolled and broken through large deformation, and the deformation energy is accumulated for the subsequent aging process. Precipitation of various precipitation phases; wherein the total deformation of hot rolling in the rolling process is 70-80%, and the total deformation of cold rolling is 70-90%;

(6) Finishing rolling: the finished cold-rolled sheet is cleaned, straightened and edge trimmed to obtain finished alloy sheets of plates, strips and foils, and the finish rolling deformation is 50%;

(7) Annealing: perform stress relief annealing at 200° C. for 4 hours on the finish-rolled sheet, and use gas protection to obtain a high-strength and high-conductivity copper-iron alloy.

Take the alloy ingot sample prepared in this example and observe it with a metallographic microscope. The typical as-cast microstructure photo of the alloy is shown in Figure 1 . It can be seen from Figure 1 that the grains in the alloy are fine and uniform, and there are a few primary iron-silicon and copper-calcium phases dispersed uniformly between the grains.

Please refer to FIG. 2 , which is the backscattered electron scanning electron microscope picture of the finished sheet in Example 1 of the present invention. It can be seen from FIG. 2 that the primary phase existing in the as-cast state in the alloy is significantly elongated and broken.

Please refer to FIG. 3 and FIG. 4 in combination, wherein FIG. 3 is the tensile curve diagram of the finished sheet in Example 1 of the present invention; FIG. 4 is the microscopic topography of the tensile fracture of the finished sheet in Example 1 of the present invention; It can be seen that the tensile strength of the finished sheet in this embodiment is as high as 732Mpa; it can be seen from Figure 4 that the fracture mode of the alloy is quasi-cleavage fracture, the section of the quasi-cleavage fracture is relatively flat, and cleavage steps appear, forming a large number of Larger dimples, which means better elongation of the alloy.

Example 2

A high-strength and high-conductivity copper-iron alloy, comprising the following components by weight percentage:

Fe: 2.0wt%, Si: 0.2wt%, Mg: 0.3wt%, Cr: 0.2wt%, Zr: 0.05wt%, Ca: 0.01wt%, and the balance is Cu;

Electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy are selected as raw materials for each component.

The preparation process of the high-strength and high-conductivity copper-iron alloy in this embodiment is the same as that of Embodiment 1.

Example 3

A high-strength and high-conductivity copper-iron alloy, comprising the following components by weight percentage:

Fe: 5wt%, Si: 0.5wt%, Mg: 0.05wt%, Cr: 0.4wt%, Zr: 0.04wt%, Ca: 0.01wt%, the balance is Cu;

Electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy are selected as raw materials for each component; The alloy is a Cu-50Zr master alloy, and the copper-calcium master alloy is a Cu-50Ca master alloy.

The preparation process of the high-strength and high-conductivity copper-iron alloy in this embodiment is the same as that of Embodiment 1.

Example 4

A high-strength and high-conductivity copper-iron alloy, comprising the following components by weight percentage:

Fe: 0.5wt%, Si: 0.1wt%, Mg: 0.5wt%, Cr: 0.5wt%, Zr: 0.15wt%, Ca: 0.15wt%, the balance is Cu;

Electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy are selected as raw materials for each component; The alloy is a Cu-50Zr master alloy, and the copper-calcium master alloy is a Cu-50Ca master alloy.

The preparation process of the high-strength and high-conductivity copper-iron alloy in this embodiment is the same as that of Embodiment 1.

Example 5

A high-strength and high-conductivity copper-iron alloy, comprising the following components by weight percentage:

Fe: 1.5wt%, Si: 0.05wt%, Mg: 0.2wt%, Cr: 0.3wt%, Zr: 0.08wt%, Ca: 0.04wt%, the balance is Cu;

Electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium master alloy, copper-zirconium master alloy and copper-calcium master alloy are selected as raw materials for each component; The alloy is a Cu-50Zr master alloy, and the copper-calcium master alloy is a Cu-50Ca master alloy.

The preparation process of the high-strength and high-conductivity copper-iron alloy in this embodiment is the same as that of Embodiment 1.

Comparative Example 1

A copper alloy comprising the following components by weight:

Fe: 2.5 wt %, Si: 0.2 wt %, and the balance is Cu; the components are electrolytic copper, pure iron, and pure silicon in proportions.

The preparation process of the copper alloy in this example is the same as that in Example 1.

Comparative Example 2

A copper alloy comprising the following components by weight:

Fe: 2.5wt%, Si: 0.2wt%, Cr: 0.2wt%, Zr: 0.08wt%, and the balance is Cu; each component is selected from electrolytic copper, pure iron, pure silicon, pure chromium, and copper-zirconium master alloy. .

The preparation process of the copper alloy in this example is the same as that in Example 1.

The high-strength and high-conductivity CuFeMgSiCrZrCa alloys of Examples 1-5 and the copper alloys prepared in Comparative Examples 1-2 were tested for performance. The test results are shown in Table 1:

Table 1: Performance table of copper alloy obtained by each embodiment

It can be seen from Table 1 that the addition of Mg and Ca will greatly increase the strength of the alloy on the basis of a slight decrease in the electrical conductivity, so that the electrical conductivity and strength properties of the alloy can be improved in a relatively balanced manner, thereby improving the overall performance of the copper-iron alloy.

Compared with the prior art, the high-strength and high-conductivity copper-iron alloy and the preparation method thereof provided by the present invention have beneficial effects as follows:

1. The high-strength and high-conductivity copper-iron alloy and its preparation method provided by the present invention utilize the microalloying of Mg, Si, Cr, Zr and Ca to promote the refinement of grains and the spheroidization of precipitated phases. The FeSi phase, CuCa phase and Cr phase precipitated in the alloy are pinned at the grain boundary, which improves the mechanical properties of the alloy. At the same time, the addition of microalloying elements also promoted the precipitation of primary iron phase during casting and solidification, while the semi-grown CuCa phase beside the primary iron phase inhibited the growth of the primary iron phase. With the subsequent cold deformation processing, the micron-scale primary iron phase and the accompanying CuCa phase are broken into sub-micron-scale secondary phases, and the nano-scale iron and chromium phases precipitated in the combined deformation and aging heat treatment process affect the alloy from multiple scales. The mechanical properties are strengthened, and the precipitated iron phase promotes the improvement of the electrical conductivity of the alloy. A small amount of Mg dissolved in the copper matrix can greatly improve the work hardening ability of the matrix on the basis of a small loss of electrical conductivity. The high-strength and high-conductivity copper-iron alloy of the present invention fully utilizes solid solution strengthening, precipitation strengthening, grain refinement strengthening and work hardening to achieve synergistic improvement of tensile strength and electrical conductivity, the tensile strength can reach 720-750MPa, and the electrical conductivity can reach Achieving 70-72% IACS, achieving a balance of alloy strength and electrical conductivity.

2. The high-strength and high-conductivity copper-iron-based alloy provided by the present invention and the preparation method thereof, the alloy composition is designed with a relatively low content of iron, which greatly reduces the production difficulty of copper-iron alloys using ordinary smelting processes to prepare sheet, strip and foil, and reduces the The macroscopic defects of copper-iron alloy sheet, strip and foil are eliminated, and the alloy properties are more stable. The alloy preparation method of the invention has the advantages of simple and easy process, low cost, and is suitable for large-scale industrial production.

The embodiments of the present invention have been described above in detail, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and alterations to these embodiments without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims (6)

1. The high-strength high-conductivity copper-iron alloy is characterized by comprising the following components in percentage by weight:

fe: 0.5 to 5.0 wt%, Si: 0.05 to 0.5wt%, Mg: 0.05 to 0.5 weight percent, more than or equal to 0.2 weight percent and less than or equal to 0.5 weight percent of Cr, more than or equal to 0.04 weight percent and less than or equal to 0.15 weight percent of Zr, more than or equal to 0.01 weight percent and less than or equal to 0.15 weight percent of Ca, and the balance of Cu;

the preparation method of the high-strength high-conductivity copper-iron alloy comprises the following steps:

step S1, proportioning the elements required by the alloy according to the design components, smelting in inert gas, and casting to obtain a copper alloy ingot;

step S2, carrying out homogenization annealing on the copper alloy ingot casting in the step S1, wherein the annealing temperature is 920-970 ℃, the annealing time is 24-48h, and the homogenized ingot casting is cooled to 800-900 ℃;

step S3, the total deformation of hot rolling cogging of the rolling process is 70-80%, and the total deformation of cold rolling is 70-90%; after cold rolling, the blank is subjected to aging heat treatment at the temperature of 300-500 ℃, and the cold rolling-aging treatment process is repeated for two or more times; cleaning, straightening and trimming a cold-rolled sheet finished product to obtain a sheet, strip and foil finished alloy sheet, wherein the finish rolling deformation is 50%; finally, the plate is subjected to stress relief annealing at the temperature of 200-300 ℃ for 4-5h to prepare the high-strength high-conductivity copper-iron alloy;

the final aging heat treatment time is 16-32h, and the rest aging heat treatment time is 1-2 h.

2. The high-strength high-conductivity copper-iron alloy according to claim 1, wherein in step S1, electrolytic copper, pure iron, pure silicon, pure chromium, copper-magnesium intermediate alloy, copper-zirconium intermediate alloy, and copper-calcium intermediate alloy are selected as raw materials.

3. The high-strength high-conductivity copper-iron alloy according to claim 2, wherein the copper-magnesium master alloy is a Cu-30Mg master alloy, the copper-zirconium master alloy is a Cu-50Zr master alloy, and the copper-calcium master alloy is a Cu-50Ca master alloy.

4. The high-strength high-conductivity copper-iron alloy according to claim 1, wherein in step S1, melting is performed by using a vacuum melting furnace with a vacuum degree of 10 ^-5 -10 ^-3 Pa, the inert gas is high-purity argon; in the smelting process, a low-frequency magnetic field generated by an induction smelting furnace is adopted to stir the melt.

5. A preparation method of a high-strength high-conductivity copper-iron alloy is characterized by comprising the following steps:

step S1, proportioning the elements required by the alloy according to the design components, smelting in inert gas, and casting to obtain a copper alloy ingot;

the alloy comprises the following components in percentage by weight:

fe: 0.5 to 5.0 wt%, Si: 0.05 to 0.5wt%, Mg: 0.05 to 0.5 weight percent, more than or equal to 0.2 weight percent and less than or equal to 0.5 weight percent of Cr, more than or equal to 0.04 weight percent and less than or equal to 0.15 weight percent of Zr, more than or equal to 0.01 weight percent and less than or equal to 0.15 weight percent of Ca, and the balance of Cu;

step S2, carrying out homogenization annealing on the copper alloy ingot casting in the step S1, wherein the annealing temperature is 920-970 ℃, the annealing time is 24-48h, and the homogenized ingot casting is cooled to 800-900 ℃;

step S3, the total deformation of hot rolling cogging of the rolling process is 70-80%, and the total deformation of cold rolling is 70-90%; after cold rolling, the blank is subjected to aging heat treatment at the temperature of 300-500 ℃, and the cold rolling-aging treatment process is repeated for two or more times; cleaning, straightening and trimming a cold-rolled sheet finished product to obtain a sheet, strip and foil finished alloy sheet, wherein the finish rolling deformation is 50%; finally, the plate is subjected to stress relief annealing at the temperature of 200-300 ℃ for 4-5h to prepare the high-strength high-conductivity copper-iron alloy;

the final aging heat treatment time is 16-32h, and the rest aging heat treatment time is 1-2 h.

6. The method for preparing the high-strength high-conductivity copper-iron alloy according to claim 5, wherein in step S1, electrolytic copper, pure iron, pure silicon, pure chromium, a copper-magnesium intermediate alloy, a copper-zirconium intermediate alloy and a copper-calcium intermediate alloy are selected as raw materials; wherein the copper-magnesium intermediate alloy is an intermediate alloy of Cu-30Mg, the copper-zirconium intermediate alloy is an intermediate alloy of Cu-50Zr, and the copper-calcium intermediate alloy is an intermediate alloy of Cu-50 Ca.

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