CN114086027A

CN114086027A - High-temperature softening resistant Cu-Ni-Sn series high-strength high-elasticity copper alloy and preparation method thereof

Info

Publication number: CN114086027A
Application number: CN202111410050.3A
Authority: CN
Inventors: 郭诚君; 乐顺聪; 安桂焕; 肖翔鹏; 黄剑; 时雨凡
Original assignee: Jiangxi University of Science and Technology
Current assignee: Jiangxi University of Science and Technology
Priority date: 2021-11-25
Filing date: 2021-11-25
Publication date: 2022-02-25

Abstract

The invention discloses a high-strength high-elasticity Cu-Ni-Sn alloy with high temperature softening resistance and a preparation method thereof, wherein the alloy comprises the following components of Cu, Ni, Sn, Al, Zn, Si or Nb and inevitable impurity elements, and the contents of the Ni, Sn, Al, Zn, Si or Nb elements are as follows: ni: 12-18 wt%; sn: 4.5-8.5 wt%; al: 0.5-2 wt%; zn: 0.3-1.0 wt%; si: 0.3-1.0 wt%; nb: 0 to 1.0 wt%. The preparation process of the alloy comprises the following steps: smelting, upward continuous casting, homogenizing and solution treatment, cold deformation treatment and aging treatment. The multicomponent Cu-Ni-Sn copper alloy prepared by the short-process up-drawing continuous casting method has small dendritic crystal spacing, and after the processes of large-deformation cold processing and combined shape heat treatment, high-melting-point second-phase particles can be separated out to occupy the nucleation positions of discontinuous precipitates, so that the recrystallization reaction is promoted, and the growth of the discontinuous precipitates is remarkably inhibited, thereby preparing the copper alloy with excellent high-temperature softening resistance, high strength, high elasticity and high wear resistance.

Description

High-temperature softening resistant Cu-Ni-Sn series high-strength high-elasticity copper alloy and preparation method thereof

Technical Field

The invention belongs to the field of nonferrous metal processing, and relates to a Cu-Ni-Sn series high-strength high-elasticity copper alloy with high-temperature softening resistance and a preparation method thereof.

Background

With the rapid development of the information industry and the modern industry, the application range of copper and copper alloy is increasingly wide, the demand is continuously increased, and the copper and copper alloy material becomes one of the most important basic materials for the national economy and social development. The high-strength high-elasticity copper alloy material is one of the advanced copper alloy materials at present, is an indispensable key material for important special science and technology and development and progress of strategic emerging industries in China, and is widely applied to high and new technical fields such as new-generation information technology, energy-saving and new-energy automobiles, advanced rail transit equipment, aerospace equipment, ocean engineering and the like.

In the high-strength high-elasticity copper alloy market in China, beryllium copper still occupies a large market scale due to the characteristics of good formability, excellent elasticity and the like. However, toxic dust is easily generated in the preparation process, the harm is caused to the health of workers, the environment is seriously polluted, in addition, the stability of the beryllium bronze is poor when the beryllium bronze works in the environment of more than 150 ℃, the stress relaxation resistance is low, and in addition, the deformation degree of elements after aging is large, so the production process is complex, and the production energy consumption is high. With the falling of the national normalized severe environmental protection policy and the energy consumption dual-control policy, the preparation of the high-strength high-elasticity copper alloy which is safe, non-toxic, simple in process, high in cost performance and higher in performance has important significance. The copper-nickel-tin series high-strength high-elasticity copper alloy has the performance equivalent to that of beryllium copper, has better thermal stress relaxation resistance, and has wide application in the elastic elements of wear-resistant bearings, bearing bushes, shaft sleeves, high-power electronic elements, precise plug-in terminals, optical instruments, sensors and the like in recent years.

The Cu-Ni-Sn alloy has high Sn element content, so that serious dendrite segregation is easily generated when the alloy is prepared by adopting a common induction melting and casting method, and the alloy can be improved only by subsequent high-temperature long-time homogenization treatment, thereby being not beneficial to the requirements of industrial production and energy conservation and consumption reduction. In addition, discontinuous precipitation reaction occurs in the alloy at the later stage of aging, the formed cellular discontinuous precipitation structure can seriously deteriorate the performance of the alloy, and the discontinuous precipitation reaction is intensified along with the rise of temperature, so that the alloy is required to have high strength, high elasticity and electric conductivity and good high temperature softening resistance. The invention adopts micro-alloying treatment and improved preparation process, can regulate and control the microstructure and microstructure of Cu-Ni-Sn alloy, and achieves the aims of improving the alloy performance, improving the production efficiency and reducing the production cost.

Disclosure of Invention

The invention aims to solve the technical problem of providing a high-strength high-elasticity Cu-Ni-Sn alloy with high-temperature softening resistance and a preparation method thereof, wherein the preparation method can effectively improve dendritic crystal segregation of the alloy, improve the high-temperature softening resistance, strength, elasticity and wear resistance of the alloy, and has the advantages of simple preparation process, high efficiency, low cost and the like.

In order to realize the purpose of the invention, the following technical scheme is adopted:

the invention relates to a high-strength high-elasticity Cu-Ni-Sn alloy with high temperature softening resistance, which comprises the following components of Cu, Ni, Sn, Al, Zn, Si or Nb and inevitable impurity elements, wherein Cu is an alloy matrix, Ni, Sn, Al, Zn, Si or Nb is a main alloy element, and the content of the main alloy element is as follows:

ni content: 12 to 18 weight percent;

sn content: 4.5-8.5 wt%;

al content: 0.5-2 wt%;

the Zn content is as follows: 0.3-1.0 wt%;

si content: 0.3-1.0 wt%;

nb content: 0 to 1.0 wt%.

In addition, the alloy also contains trace elements such as Co, P, Fe, Ag, Cr, Zr, Ti, V and the like, and the total content of the elements is not more than 0.1 wt%.

In a preferred embodiment of the invention, the high-strength and high-elasticity copper alloy of the Cu-Ni-Sn series for resisting high-temperature softening has the following optimized components:

ni content: 14.0-16.0 wt%;

sn content: 4.5-6.5 wt%;

al content: 1.0-1.8 wt%;

the Zn content is as follows: 0.3-0.6 wt%;

si content: 0.3-0.6 wt%;

nb content: 0.3 to 0.6 wt%.

Through the optimization of the components, the invention can further improve the comprehensive performance of the alloy.

In a preferred embodiment of the invention, the Cu-Ni-Sn series high-strength high-elasticity copper alloy with high temperature softening resistance has the strength of 1200-1600 MPa, the elastic modulus of 135-150GPa and the softening resistance temperature of 580-650 ℃ after upward continuous casting and multi-pass deformation heat treatment.

The invention also relates to a preparation process of the high-strength and high-elasticity Cu-Ni-Sn alloy with high temperature softening resistance, which comprises the steps of smelting, upward continuous casting, homogenizing and solution treatment, and combined thermomechanical treatment, and specifically comprises the following steps:

the method comprises the following steps: adding pure nickel blocks into molten copper, then adding a covering agent, controlling the smelting temperature in the smelting furnace at 1200-1300 ℃, keeping the temperature for 5-8 minutes after the pure nickel blocks are completely molten, filling inert gas for refining, then sequentially adding Si, Nb, Al, Sn, Zn and other alloy elements, and uniformly mixing the alloy elements in the copper water.

Step two: and cooling the mixed melt to 1120-1180 ℃, then enabling the alloy liquid in the smelting furnace to enter an up-drawing continuous casting crystallizer by using a siphon principle, and performing cooling crystallization in the up-drawing continuous casting crystallizer through a cooling water system, wherein the pressure of cooling water in the crystallizer is 0.3-0.5MPa in order to ensure the cooling effect.

Step three: the alloy casting blank is subjected to homogenization treatment and then is rapidly cooled by water to achieve the effect of solution treatment, and the temperature of cooling water for water quenching is 20-35 ℃. The temperature and time of the homogenizing and solution treatment process are selected according to the Sn content, and when the Sn content is 4.5-5.5 wt%, the homogenizing process is carried out at 850-880 ℃ for 2-6 h; when the Sn content is 5.5-6.5 wt.%, the homogenization process is carried out at 880-910 ℃ for 4-8 h; when the Sn content is 6.5-8 wt.%, the homogenization process is carried out for heat preservation for 6-12h at 910-950 ℃;

step four: and (3) carrying out deformation and heat treatment on the sample subjected to homogenization and solution treatment in the third step, wherein the specific process comprises the following steps: primary cold deformation (70% to 90% of total deformation), primary aging treatment (400 ℃ to 450 ℃ and 3-8h), secondary cold deformation (50% to 70% of total deformation) and secondary aging treatment (300 ℃ to 400 ℃ and 1-5 h).

The covering agent is a mixture of high-quality wood carbon and graphite flakes, wherein the high-quality wood carbon and the graphite flakes respectively account for 50%, and the thickness of the covering agent is 80-100 mm. The method has the advantages that the solubility of hydrogen in the alloy is increased by adding Ni into the copper liquid, so that the prepared alloy seriously absorbs hydrogen to deteriorate the alloy processing performance, and the contact between the alloy liquid and air can be isolated by adopting a mixture of high-quality charcoal and graphite flakes as a covering agent, so that the air suction of the alloy liquid is reduced.

The inert refining gas is argon or nitrogen, and the degassing refining time is 8-15 min. In order to ensure the degassing refining effect, the gas is dehydrated before degassing refining, so that the oxygen content of the charged refining gas is less than 0.03 percent, and the water content is less than 3.0 g/L.

The alloy elements such as Si, Nb, Al, Sn, Zn and the like are sequentially added, the Zn element is added in a Cu-Zn intermediate alloy mode to reduce volatilization of the Zn element, and the metal elements such as Si, Nb, Al, Sn and the like can be added in a pure metal or intermediate alloy mode.

The melt temperature before the upward continuous casting is determined according to the content of Ni element, when the content of Ni is 12-15 wt.%, the melt temperature before the upward continuous casting is between 1120-1150 ℃, and when the content of Ni is 15-18 wt.%, the melt temperature before the upward continuous casting is between 1150-1180 ℃, the liquid level height change of the melt in the traction process is not more than +/-20 mm, the cooling water inlet temperature of the upward crystallizer is not more than 30 ℃, and the water outlet temperature is not more than 50 ℃.

The crystallizer used for the up-drawing continuous casting is a boron nitride material with high heat resistance and low ultrasonic attenuation, and is characterized in that the boron nitride material has no chemical reaction with the main components of the alloy, in addition, in order to improve the traction efficiency, a multi-head continuous traction mode can be adopted in the actual production, the pitch in the up-drawing continuous casting process is 1-3mm, and the continuous traction speed is not lower than 100 cm/min.

In the upward continuous casting process, the size of a casting blank is selected according to the content of Sn element, and when the content of Sn is 4.5-5.5 wt.%, the diameter of a round casting rod is not more than 30 mm; when the Sn content is 5.5-6.5 wt.%, the diameter of the round casting rod is not more than 25 mm; when the Sn content is 6.5-8 wt.%, the maximum diameter of the round casting rod is not more than 20mm, so that the anti-segregation of the prepared alloy casting blank is avoided.

And the total deformation of the second cold working is less than or equal to that of the first cold working, and the pass deformation of the second cold working is less than or equal to that of the first cold working.

The aging treatment temperature is 300-450 ℃, the aging time is 1-8h, and the temperature of primary aging is higher than that of secondary aging, so as to ensure that the alloy obtains excellent tissues and high softening temperature resistance.

According to the invention, Cu, Ni, Sn, Al, Zn, Si or Nb is used as a raw material, and the alloy is prepared by a method combining multiple strengthening modes such as smelting, up-drawing continuous casting, homogenization and solution treatment, thermomechanical treatment and the like, so that the alloy performance is obviously improved, the strength of the alloy reaches 1200-1600 MPa, the elastic modulus reaches 135-150GPa, the softening resistance temperature is 580-650 ℃, the problem of insufficient high-temperature softening resistance of the existing Cu-Ni-Sn series high-strength high-elasticity copper alloy is solved, and the development requirements of high-performance conductive elastic devices in the aerospace industry, the aviation industry and the microelectronic industry are met.

The beneficial results obtained by the invention are as follows:

1) the method can improve the segregation problem of the as-cast structure of the Cu-Ni-Sn alloy by the up-casting continuous casting method, has the advantages of safety, environmental protection, high efficiency and energy conservation, and meets the requirements of the environmental protection policy and the energy consumption double control policy in China. Specifically, the purposes of reducing dendrite spacing, eliminating microscopic and macroscopic segregation of the alloy, reducing production flow and simplifying production process are achieved by controlling the content of Sn element, the size of cast ingot and the up-drawing continuous casting process.

2) The microstructure and microstructure of the Cu-Ni-Sn series copper alloy are regulated and controlled by an alloying method, discontinuous precipitation at the later aging stage of the alloy is inhibited, the strength and hardness of the Cu-Ni-Sn series copper alloy are obviously improved, and meanwhile, the high-temperature softening resistance of the Cu-Ni-Sn series copper alloy is greatly improved. The single addition or the composite addition of Al, Zn, Si or Nb can effectively inhibit the nucleation and the growth of discontinuous precipitates. Wherein the addition of Si or Nb can form coarse Ni with Ni₃₁Si₁₁Phase or Ni₃The Nb phase occupies the nucleation position of the discontinuous precipitation on one hand, promotes the occurrence of recrystallization reaction on the other hand, and remarkably inhibits the formation and growth of the discontinuous precipitation phase through comprehensive action, thereby improving the high-temperature aging resistance and high-temperature softening resistance of the alloy; al element replaces Sn to keep the original performance of the alloy and reduce the segregation of Sn; zn exists in the alloy mainly in a solid solution atom mode, and contributes greatly to the mechanical property and the high-temperature softening resistance of the alloy. The composite addition of Al, Zn, Si or Nb elements can improve the microstructure and structure of the alloy on one hand, and can obviously improve the performance of the alloy on the other hand, and finally the high-strength high-elasticity Cu-Ni-Sn series copper alloy with excellent high-temperature softening resistance is prepared.

3) The Cu-Ni-Sn-Al-Zn-Si, Cu-Ni-Sn-Al-Zn-Nb and Cu-Ni-Sn-Al-Zn-Si-Nb alloys have better comprehensive performance, and the tensile strength, the elastic modulus and the softening temperature can reach 1200-1600 MPa, 135-150GPa and 580-650 ℃ respectively.

Drawings

FIG. 1 is an as-cast structure diagram of example 1.

FIG. 2 is an as-cast structure diagram of comparative example 1.

As can be seen from fig. 1 and 2, the Cu-Ni-Sn copper alloy prepared by the conventional induction melting casting method has coarse dendrite of the as-cast structure and serious components, and the alloy prepared by the up-drawing continuous casting method can significantly reduce the dendrite spacing of the as-cast structure and make the distribution thereof more uniform.

Detailed Description

The invention is further described below with reference to the following examples:

example 1:

step one, according to alloy components: 15 wt.% Ni, 6 wt.% Sn, 1.4 wt.% Al, 0.5 wt.% Zn, 0.5 wt.% Si, the balance being pure copper. Wherein the purity of Ni, Sn, Al, Zn, Si is 99.95 wt.%. Putting the prepared copper into a melting crucible, and respectively putting Ni, Sn, Al, a commercially available Cu-5Zn intermediate alloy and Si elements onto a feeding tray; starting smelting, after pure copper is completely melted, adding a pure nickel block, adding a covering agent mixture of high-quality wood carbon and graphite flakes, controlling the temperature at 1200-1300 ℃, after the pure nickel block is completely melted, preserving the heat for 5-8 minutes, and filling argon or nitrogen to stir and degas the melt; and then sequentially adding Si, Al, Sn and Cu-Zn intermediate alloy, preserving heat for 3-5 min, and cooling the melt to 1150 ℃ to prepare for up-drawing continuous casting.

And secondly, adopting a boron nitride material as a crystallizer material, enabling the alloy liquid in the smelting furnace to enter an upward continuous casting crystallizer by utilizing a siphon principle, cooling and crystallizing in the upward continuous casting crystallizer through a cooling water system, wherein the pressure of cooling water of the crystallizer is 0.3-0.5MPa, the water inlet temperature of the cooling water of the upward crystallizer is less than or equal to 30 ℃, the water outlet temperature is less than or equal to 50 ℃, the liquid level height of the melt in the traction process does not exceed +/-20 mm, the pitch in the upward continuous casting process is 3mm, the continuous traction speed is 120cm/min, and the diameter of the finally drawn round casting rod is 22 mm.

And step three, homogenizing the alloy casting rod at 890 ℃ for 7 hours, and then rapidly cooling with water to obtain the supersaturated solid solution alloy.

And step four, carrying out deformation and heat treatment on the alloy rod material obtained in the step three, firstly carrying out primary cold working treatment on the alloy rod material, wherein the total deformation amount of the primary cold working is 80%, then carrying out aging treatment at 400 ℃ for 4h, then carrying out secondary cold working treatment, wherein the total deformation amount of the secondary cold working is 60%, and then carrying out aging treatment at 350 ℃ for 3h, wherein the as-cast structure of the alloy rod material is shown in figure 1.

Comparative example 1:

the other conditions were the same as in example 1 except that: the alloy composition is Cu-15Ni-8Sn alloy, no other elements are added, and the alloy rod blank is prepared by adopting a vacuum melting-casting mode, and the cast structure of the alloy rod blank is shown in figure 2.

Example 2:

step one, according to alloy components: 15 wt.% Ni, 6 wt.% Sn, 1.6 wt.% Al, 0.8 wt.% Zn, 0.6 wt.% Nb, the balance being pure copper. Wherein the purity of Ni, Sn, Al, Zn and Nb is 99.95 wt.%. Putting the prepared copper into a melting crucible, and respectively putting Ni, Sn, Al, Cu-5Zn intermediate alloy and Nb elements onto a feeding tray; starting smelting, after pure copper is completely melted, adding a pure nickel block, adding a covering agent mixture of high-quality wood carbon and graphite flakes, controlling the temperature at 1200-1300 ℃, after the pure nickel block is completely melted, preserving the heat for 5-8 minutes, and filling nitrogen or argon to stir and degas the melt; then sequentially adding Nb, Al, Sn and Cu-Zn intermediate alloy, preserving heat for 3-5 min, and cooling the melt to 1160 ℃ for preparation of up-drawing continuous casting.

And step three, homogenizing the alloy cast rod at 900 ℃ for 4 hours, and then rapidly cooling by water to obtain a supersaturated solid solution state.

And step four, carrying out deformation and heat treatment on the alloy rod material obtained in the step three, firstly carrying out primary cold working treatment on the alloy rod material, wherein the total deformation amount of the primary cold working is 85%, then carrying out aging treatment at 400 ℃ for 3h, then carrying out secondary cold working treatment, wherein the total deformation amount of the secondary cold working is 65%, and then carrying out aging treatment at 350 ℃ for 4 h.

The other conditions were the same as in example 3 except that: the alloy composition is Cu-15Ni-6Sn alloy, and no other elements are added.

Example 3:

step one, according to alloy components: 15 wt.% Ni, 4.8 wt.% Sn, 1.2 wt.% Al, 0.5 wt.% Zn, 0.5 wt.% Si, 0.5 wt.% Nb, and the balance pure copper. Wherein the purity of Ni, Sn, Al, Zn, Si and Nb is 99.95 wt.%. Putting the prepared copper into a melting crucible, and respectively putting Ni, Sn, Al, Cu-Zn intermediate alloy, Si and Nb elements onto a feeding tray; starting smelting, after pure copper is completely melted, adding a pure nickel block, adding a covering agent mixture of high-quality wood carbon and graphite flakes, controlling the temperature at 1200-1300 ℃, after the pure nickel block is completely melted, preserving the heat for 5-8 minutes, and filling argon gas to stir and degas the melt; then sequentially adding Nb, Si, Al, Sn and Cu-10Zn intermediate alloy, preserving heat for 3-5 min, and cooling the melt to 1150 ℃ to prepare for up-drawing continuous casting.

And secondly, adopting a boron nitride material as a crystallizer material, enabling the alloy liquid in the smelting furnace to enter an upward continuous casting crystallizer by utilizing a siphon principle, cooling and crystallizing in the upward continuous casting crystallizer through a cooling water system, wherein the pressure of cooling water of the crystallizer is 0.3-0.5MPa, the water inlet temperature of the cooling water of the upward crystallizer is less than or equal to 30 ℃, the water outlet temperature is less than or equal to 50 ℃, the liquid level height of the melt in the traction process does not exceed +/-20 mm, the pitch in the upward continuous casting process is 3mm, the continuous traction speed is 110cm/min, and the diameter of the finally drawn round casting rod is 26 mm.

Step three, homogenizing the alloy cast rod at 870 ℃ for 6 hours, and then rapidly cooling by water to obtain a supersaturated solid solution state.

And step four, carrying out deformation and heat treatment on the alloy rod material obtained in the step three, firstly carrying out primary cold machining treatment on the alloy rod material, wherein the total deformation of the primary cold machining is 90%, then carrying out aging treatment at 400 ℃ for 5h, then carrying out secondary cold machining treatment, wherein the total deformation of the secondary cold machining is 70%, and then carrying out aging treatment at 350 ℃ for 4 h.

Comparative example 3:

the other conditions were the same as in example 3 except that: the alloy composition is Cu-15Ni-4.8Sn alloy, and no other elements are added.

TABLE 1 final mechanical properties, modulus of elasticity and temperature resistance test results for the example and comparative example alloys

Through the research, the Cu-Ni-Sn series copper alloy prepared by the method of upward continuous casting and alloying can obviously reduce the dendrite spacing, eliminate the micro and macro segregation of the alloy, reduce the production flow, simplify the production process, and obviously improve the tensile strength, the elastic modulus and the softening resistance temperature of the alloy, thereby being particularly suitable for the application of high-performance conductive elastic devices in the aerospace industry, the aviation industry and the microelectronic industry.

The foregoing describes preferred embodiments of the present invention, but is not intended to limit the invention thereto. Modifications and variations of the embodiments disclosed herein may be made by those skilled in the art without departing from the scope and spirit of the invention.

Claims

1. A Cu-Ni-Sn system alloy, the composition of the alloy comprises Cu, Ni, Sn, Al, Zn, Si or Nb and inevitable impurity elements, wherein Cu is an alloy matrix, and Ni and Sn are main alloys Elements, Al, Zn, Si or Nb are alloying elements and their content:

Ni content: 12-18wt%;

Sn content: 4.5～8.5wt%;

Al content: 0.5～2wt%;

Zn content: 0.3～1.0wt%;

Si content: 0.3～1.0wt%;

Nb content: 0～1.0wt%;

In addition, the alloy also contains trace elements such as Co, P, Fe, Ag, Cr, Zr, Ti, V, etc., the total content of which is not higher than 0.1wt%;

The remainder is Cu.

2. Cu-Ni-Sn system copper alloy according to claim 1, the alloying element composition of optimization is as follows:

Ni content: 14.0-16.0wt%;

Sn content: 4.5～6.5wt%;

Al content: 1.0～1.8wt%;

Zn content: 0.3～0.6wt%;

Si content: 0.3～0.6wt%;

Nb content: 0.3 to 0.6 wt%.

In addition, the alloy also contains trace elements such as Co, P, Fe, Ag, Cr, Zr, Ti, V, etc., the total content of which is not higher than 0.1 wt%.

3 . The Cu-Ni-Sn copper alloy according to claim 1 and 2 , wherein the strength of the alloy is 1200-1600 MPa, the elastic modulus is 135-150 GPa, and the softening resistance temperature is 580-650° C. 4 .

4. according to the preparation method of the described Cu-Ni-Sn system alloy of any one of claim 1-3, it is characterized in that, comprise the step of smelting-upward continuous casting-homogenization and solution treatment-combined deformation heat treatment, concrete as follows:

Step 1: Put pure nickel blocks into the molten copper liquid, and then put in the covering agent. The melting temperature in the smelting furnace is controlled at 1200-1300 ° C. When the pure nickel blocks are completely melted, they are kept for 5-8 minutes and charged. Enter inert gas for refining, and then pour in the main alloying elements and alloying raw materials in turn, and wait for them to be mixed evenly in copper water;

Step 2: Cool the above-mentioned mixed molten liquid to 1120-1180 ° C, and then use the siphon principle to make the alloy liquid in the melting furnace enter the upper continuous casting mold, and conduct the cooling water system in the upper continuous casting mold. Cooling crystallization, in order to ensure the cooling effect, the pressure of the cooling water of the crystallizer is 0.3-0.5MPa;

Step 3: The above-mentioned alloy casting billet is first subjected to homogenization treatment and then rapidly water-cooled to achieve the effect of solution treatment. The cooling water temperature of the water quenching is 20-35°C. The process temperature and time of the homogenization and solution treatment are selected according to the Sn content. When the Sn content is 4.5-5.5wt.%, the homogenization process is kept at 850℃-880℃ for 2-6h; the Sn content is 5.5-6.5wt.%. %, the homogenization process is 880℃-910℃ for 4-8h; when the Sn content is 6.5～8wt.%, the homogenization process is 910℃-950℃ for 6-12h;

Step 4: Perform deformation and heat treatment on the samples after homogenization and solution treatment in Step 3. The specific process is: one-time cold deformation, 70%≤total deformation amount≤90%→one-time aging treatment, 400-450℃, 3-8h →Secondary cold deformation, 50%≤total deformation≤70% →Secondary aging treatment, 300-400℃, 1-5h.

5. preparation method according to claim 4 is characterized in that: the covering agent described in step 1 is the mixture of charcoal and graphite flakes, and wherein the weight ratio of charcoal and graphite flakes is 1-2:1-2, The thickness of the covering agent is 80-100mm.

6 . The preparation method according to claim 4 , wherein the inert refining gas charged in step 1 is argon or nitrogen, and the time for degassing and refining is 8-15 min. 7 .

7 . The preparation method according to claim 4 , wherein in step 1, the alloy elements of Si, Nb, Al, Sn, and Zn are sequentially added, and the Zn element is added in the form of a Cu-Zn master alloy. 8 .

8. preparation method according to claim 4, is characterized in that: in step 2, the melt temperature before the upward lead continuous casting is determined according to the content of Ni element, and when Ni content is 12～15wt.%, before the upward lead continuous casting When the melt temperature is between 1120-1150 °C and the Ni content is 15-18wt.%, the melt temperature before the upward continuous casting is between 1150-1180 °C, and the liquid level of the melt during the pulling process is high. The change does not exceed ±20mm, and the cooling water inlet temperature of the upper crystallizer is less than or equal to 30℃, and the outlet temperature is less than or equal to 50℃.

9 . The preparation method according to claim 4 , wherein the crystallizer used in the up-casting in step 2 is a boron nitride material with high heat resistance and low ultrasonic attenuation. 10 .

10. The preparation method according to claim 4, characterized in that: in the upward continuous casting process of step 3, the size of the slab needs to be selected according to the Sn element content, and when the Sn content is 4.5-5.5wt.%, The diameter of the round cast rod shall not exceed 30mm; when the Sn content is 5.5 to 6.5wt.%, the diameter of the round cast rod shall not exceed 25mm; when the Sn content is 6.5 ~ 8wt.%, the maximum diameter of the round cast rod shall not exceed 20mm. In order to avoid the reverse segregation of the prepared alloy casting billet.