Low-beryllium multi-component copper alloy for mold and its preparation method

Abstract

The present invention provides a low-beryllium multi-component copper alloy for a mold and a preparation method thereof. The copper alloy comprises the following elements in mass percentages: Be 0.5-1.5 wt%, Ni 0.8-1.5 wt%, Cr 0.3-0.6 wt%, Zr 0.1-0.25 wt%, Ag 0.05-0.5 wt%, rare earth 0.01-0.1 wt%, and the balance is Cu. The copper alloy of the present invention is prepared by a gas atomization powder-making - powder metallurgy method. It has a low beryllium content, reduces toxicity and cost, has uniformly fine grain size, and has the characteristics of high hardness, good thermal conductivity, and excellent heat resistance. The hardness of the copper alloy is 346-421 HV, the tensile strength is 1050-1305 MPa, the conductivity is 44.9-50.9% IACS, and the average grain size is about 9-15 μm.

Description

Technical Field

[0001] The present invention relates to the technical field of non-ferrous metal material processing, and particularly to a low-beryllium multi-component copper alloy for a mold and a preparation method thereof. Background Art

[0002] Beryllium copper alloy is a copper alloy with beryllium as the main alloying element, also known as beryllium bronze, which is a typical age-hardening alloy. After solution strengthening treatment, it has high strength and hardness, and at the same time has good corrosion resistance, wear resistance, thermal conductivity, etc. High-performance beryllium copper alloys are used in fields such as aerospace, electrical appliances, instruments and chemicals, molds, and molds.

[0003] The amorphous alloy strip casting machine requires the mold to have high thermal conductivity, strength, hardness and other properties, and at the same time also have good thermal fatigue resistance and excellent corrosion resistance. The beryllium bronze for the mold can provide a higher cooling rate for the alloy melt to obtain an amorphous structure. However, the beryllium bronze mold faces the following problems: 1) High toxicity and cost. Cu-2.6Be-0.5Co-0.3Si and Cu-2.0Be-0.5Co-0.3Si are commonly used beryllium bronze for molds. They have high hardness and good wear resistance, but the price of Be is expensive, toxic, carcinogenic, and harmful to human health; 2) It is difficult to balance the thermal conductivity and hardness. The improvement of the strength of high-strength and high-conductivity copper alloys mainly depends on the precipitation strengthening of the second phase. At the same time, the alloy needs to maintain high conductivity during strengthening. Therefore, it is necessary to develop beryllium copper alloys with low beryllium content but without reducing hardness.

[0004] When adding alloying elements to copper, three factors need to be considered: 1) The added element can form a solid solution with copper; 2) The added element has little influence on the conductivity of the copper matrix; 3) The precipitation of the alloying element can form a strengthening phase. At present, the alloying elements added to copper generally include elements such as nickel, cobalt, zirconium, titanium, and rare earths. For example, the addition of nickel and cobalt can refine the grains inside the alloy material and improve the uniformity of the internal structure; the addition of zirconium can increase the softening temperature of the beryllium copper alloy and refine the recrystallized grains; titanium can effectively enhance the strength of the beryllium copper alloy; rare earth elements can refine the grains, make the grains uniform, and can effectively improve the strength and corrosion resistance of the beryllium copper alloy. Although the above elements are added, the low-beryllium copper alloy still has the problem of low strength.

[0005] In addition, beryllium copper alloys are usually formed by casting-rolling, which is likely to cause uncontrollable and uneven distribution of grain sizes, and thus the added elements cannot play their corresponding roles well. Therefore, improving the manufacturing method of beryllium copper alloys is also an urgent problem to be solved. Summary of the Invention

[0006] The present invention provides a low-beryllium multi-component copper alloy for a mold and a preparation method thereof. The prepared copper alloy has a low beryllium content, reducing toxicity and cost. It combines the high strength of beryllium copper alloy and the high thermal conductivity of chromium copper alloy. Its grain size is uniformly fine. It has the characteristics of high hardness, good thermal conductivity and excellent heat resistance, with a hardness of 346 - 421 HV, a tensile strength of 1050 - 1305 MPa, a conductivity of 44.9 - 50.9% IACS, and an average grain size of about 9 - 15 μm.

[0007] The technical solution of the present invention is realized as follows: The low-beryllium multi-component copper alloy for a mold includes the following elements in mass percentages: Be 0.5 - 1.5 wt%, Ni 0.8 - 1.5 wt%, Cr 0.3 - 1.0 wt%, Zr 0.1 - 0.25 wt%, Ag 0.05 - 0.5 wt%, rare earth 0.01 - 0.1 wt%, and the balance is Cu.

[0008] The set range of Be content reduces cost while ensuring the strength of the alloy. The increase of Cr is beneficial to improving the strength of the alloy but will lead to a decrease in the electrical conductivity of the alloy. If the Cr content is higher than 1.0 wt%, the electrical conductivity of the alloy is lower; if the Cr content is lower than 0.3 wt%, the strength of the alloy is lower. The age hardening of Zr is not obvious, so the single addition has little effect on the strength of the alloy. In this application, Zr and Cr are added in combination to promote the age hardening effect of Cr element. The ratio of Cr element to Zr element is 3:1 - 5:1. The addition of Ag regulates the electrical conductivity of the alloy without reducing the strength of the alloy, and the addition of rare earth elements refines the grains and increases the crystallization temperature of the alloy.

[0009] The preparation method of the low-beryllium multi-component copper alloy for a mold includes the following steps:

[0010] (1) Weigh the raw materials of the low-beryllium copper alloy, melt them and then atomize them by gas to obtain metal powder.

[0011] (2) Sinter and densify the metal powder to obtain a low-beryllium copper alloy blank.

[0012] (3) Forge, solutionize and age-treat the low-beryllium copper alloy blank to obtain a low-beryllium copper alloy.

[0013] Further, in step (1), the method of atomizing by gas: After the raw materials are melted, the temperature is raised to the molten state, and then it is discharged into the gas atomizer. The discharge temperature is 1300 - 1700 °C, the gas atomization pressure is 10 - 50 MPa, the gas source is argon or nitrogen, and the metal powder is obtained by gas atomization.

[0014] Further, in step (1), the melting method is as follows: Weigh the raw materials of low-beryllium copper alloy and load them into a melting furnace. Raise the temperature of the melting furnace to 1200 - 1500 °C until the alloy is completely melted, hold for 5 - 10 min, adjust the power of the melting furnace up and down 3 - 5 times to make the raw materials melt evenly, and then let it stand for 5 - 10 min. Adjust the power of the melting furnace up and down 3 - 5 times. The power is adjusted to be large and then small. For example, the melting power is increased by 15 - 25%, held for a period of time, and then adjusted back. Repeat 3 - 5 times to generate a power difference, which has a fluctuating stirring effect and promotes homogenization.

[0015] Further, in step (2), the sintering method is die pressing - sintering, spark plasma sintering or hot isostatic pressing sintering.

[0016] Further, the specific method of die pressing - sintering is as follows: Transfer the metal powder into a mold or a cold isostatic pressing mold sleeve, and prepare a cold blank by die pressing under a pressure of 300 - 500 MPa; Put the cold blank into a sintering furnace and sinter it in a vacuum or hydrogen atmosphere to obtain a low-beryllium copper alloy blank. The sintering temperature is 750 - 1000 °C, and the holding time is 5 - 300 min.

[0017] Further, the specific method of spark plasma sintering (SPS) is as follows: Transfer the metal powder into a graphite mold, under a vacuum and a pressure of 5 - 80 MPa, raise the temperature to 750 - 980 °C, and the holding time is 3 - 60 min.

[0018] Further, for hot isostatic pressing sintering: Transfer the metal powder into a closed metal mold sleeve for hot isostatic pressing, under a pressure of 10 - 70 MPa, raise the temperature to 800 - 950 °C, and the holding time is 15 - 120 min.

[0019] Further, in step (3), the forging method is as follows: Under the condition of 750 - 850 °C, perform ring forging and ring rolling on the sintered blank, and the forging deformation rate is greater than 50% to obtain a ring-shaped workpiece.

[0020] Further, in step (3), the solution and aging treatment method is as follows: Raise the temperature of the forged workpiece to 760 - 950 °C, hold for 30 min - 3 h and then perform quenching treatment. Perform aging treatment on the quenched workpiece. The aging temperature is 350 - 500 °C, hold for 2 - 6 h, and cool to room temperature to obtain the low-beryllium copper alloy.

[0021] Further, in step (2), first put the metal powder into a ball mill tank, select grinding balls with a diameter of 12 - 20 mm, the ball-to-powder ratio is 5 - 10:1, and ball mill and mix the materials at a rotation speed of 20 - 45 r / min for 1 - 4 h, and then perform sintering densification treatment.

[0022] The beneficial effects of the present invention:

[0023] The low-beryllium copper alloy of the present invention can simultaneously exert the solution failure strengthening of Be-Ni and Cr-Zr, and has both the high strength of beryllium copper alloy and the high thermal conductivity of chromium copper alloy; the Ni element delays the decomposition of solid solution, inhibits the grain boundary reaction, and improves the precipitation hardening effect of the alloy; Zr / rare earth hinders the grain growth of copper alloy during heating, increases the crystallization temperature, and improves the stress relaxation resistance.

[0024] Compared with the casting-rolling forming process, the low-beryllium copper alloy obtained by the gas atomization powder making-powder metallurgy method of the present invention has uniform and small grain size, and at the same time improves the problem of rare earth / Ni / Co enrichment. For the beryllium copper alloy formed by casting-rolling, a second phase with high Ni / Co content is easily formed in the alloy matrix, causing the problem of Ni / Co element enrichment. However, the low-beryllium copper alloy prepared by powder metallurgy has smaller and uniform grain size, refines the second phase containing Ni / Co elements, and at the same time is beneficial to the precipitation of γ phase (Cu-Be and Cr) at the grain boundary, giving full play to the strengthening effect. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is the metallographic diagram of the microstructure of the multi-component low-beryllium copper alloy of the present invention, where: Figure 1 -a is the metallographic diagram of Comparative Example 2; Figure 1 -b is the metallographic diagram of Example 4; Figure 1 -c is the metallographic diagram of Example 1; Figure 1 -d is the metallographic diagram of Example 2. Detailed Embodiments

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] The raw materials of the low-beryllium copper alloy of the present invention are derived from electrolytic copper, beryllium copper master alloy or pure beryllium, pure nickel or nickel copper alloy, chromium copper alloy (Cu-5.0Cr), pure cobalt particles or cobalt copper alloy, pure zirconium particles or zirconium copper alloy, pure silver particles or silver copper alloy, single-element rare earth or mixed rare earth. The above raw materials comprise elements in the following mass percentages: Be 0.5-1.5 wt%, Ni 0.8-1.5 wt%, Cr 0.3-1.0 wt%, Zr 0.1-0.25 wt%, Ag 0.05-0.5 wt%, rare earth 0.01-0.1 wt%, and the balance is Cu.

[0029] Example 1

[0030] The preparation method of the low-beryllium multi-component copper alloy for the mold uses, includes the following steps:

[0031] 1) Weigh electrolytic copper, beryllium copper master alloy (Cu-2.0Be), nickel copper alloy, silver copper alloy and mixed rare earth to form a low-beryllium copper alloy component with the following mass percentages: Be 0.9 wt%, Ni 1.0 wt%, Cr 0.5 wt%, Zr 0.15 wt%, Ag 0.5 wt%, mixed rare earth (lanthanum and cerium) 0.035 wt%, and the balance is Cu;

[0032] 2) Use a vacuum induction furnace for melting, raise the temperature to 1250 °C until all the raw materials are melted, keep warm for 5 min, adjust the power of the melting furnace up and down 5 times (such as raising the melting power from 8 KW to 10 KW, keeping for 3 minutes, and then adjusting back to 8 KW, repeating 5 times) to make the raw materials melt evenly, and let it stand for 10 min;

[0033] 3) Gas atomization to make powder: Raise the temperature to make the copper alloy in a molten state, pour it out of the furnace and enter the gas atomizer. The pouring temperature is 1500 °C, the gas atomization pressure is 30 MPa, the gas atomization gas source is argon or nitrogen, and metal powder is obtained by gas atomization;

[0034] 4) Die pressing to make blanks: Grind the proportioned metal powder (for 200 min, rotation speed 30 r / min), and then transfer it into a mold for die pressing (400 MPa) to prepare cold blanks;

[0035] 5) Sintering: Put the cold blanks into a sintering furnace, use hydrogen as the protective gas, the sintering temperature is 930 °C, keep warm for 25 min, and sinter to obtain low-beryllium copper alloy blanks;

[0036] 6) Forging: Under the condition of 750-850 °C, perform ring forging and ring rolling on the sintered blanks, and the forging deformation rate is 50%;

[0037] 7) Solution and aging treatment: Heat the forged ring workpiece to 900 °C, hold for 60 min, and then perform quenching treatment. Subject the quenched workpiece to aging treatment: the aging temperature is 450 °C, hold for 200 min, and cool to room temperature to obtain a low-beryllium copper alloy ring workpiece.

[0038] In this embodiment, the properties of the obtained low-beryllium copper alloy ring workpiece are as follows: the strength is improved, the hardness reaches 346 HV, the tensile strength is 1050 MPa; the conductivity is 50.9% IACS; the average grain size is about 10 μm (see Figure 1 -c).

[0039] Example 2

[0040] The preparation method of the low-beryllium multi-component copper alloy for the mold is as follows:

[0041] 1) Weigh electrolytic copper, beryllium copper master alloy (Cu-2.0Be), pure nickel, chromium copper alloy (Cu-5.0Cr), pure zirconium particles, pure silver particles and mixed rare earths to form a low-beryllium copper alloy component with the following mass percentages: Be 0.9 wt%, Ni 1.0 wt%, Cr 0.75 wt%, Zr 0.15 wt%, Ag 0.5 wt%, mixed rare earth (lanthanum and cerium) 0.05 wt%, and the balance is Cu;

[0042] 2) Use a vacuum induction furnace for melting. Raise the temperature to 1250 °C until all the raw materials are melted, hold for 5 min, adjust the power of the melting furnace up and down 5 times to make the raw materials melt evenly, and let it stand for 10 min;

[0043] 3) Gas atomization to produce powder: Raise the temperature to make the copper alloy in a molten state, pour it into the gas atomizer, the pouring temperature is 1500 °C, the gas atomization pressure is 30 MPa, the gas atomization gas source is argon or nitrogen, and metal powder is obtained by gas atomization;

[0044] 4) Die pressing to form a blank: Ball mill the proportioned metal powder (200 min, rotation speed 30 r / min), and then transfer it into a mold for die pressing (400 MPa) to prepare a cold blank;

[0045] 5) Sintering: Put the cold blank into a sintering furnace, use hydrogen as the protective gas, the sintering temperature is 930 °C, hold for 25 min, and sinter to obtain a low-beryllium copper alloy blank;

[0046] 6) Forging: Under the condition of 750 - 850 °C, perform ring forging and ring rolling on the sintered blank, and the forging deformation rate is 60%;

[0047] 7) Solution aging treatment: Heat the forged ring workpiece to 900 °C, hold for 60 min, and then perform quenching treatment. Perform aging treatment on the quenched workpiece: The aging temperature is 450 °C, hold for 200 min, and cool to room temperature to obtain a low-beryllium copper alloy ring workpiece.

[0048] Compared with Example 1, in this example, the contents of Cr and rare earth are increased. The properties of the obtained low-beryllium copper alloy ring workpiece are as follows: The strength is further improved, the hardness is 375 HV, and the tensile strength is 1208 MPa; The conductivity decreases slightly, to 47.8% IACS; The average grain size changes little, about 10 μm (see Figure 1 -d).

[0049] Example 3

[0050] The preparation method of the low-beryllium multi-component copper alloy for the mold includes the following steps:

[0051] 1) Weigh electrolytic copper, beryllium copper master alloy (Cu-2.0Be), cobalt particles, chromium copper alloy (Cu-5.0Cr), pure zirconium particles, pure silver particles, and mixed rare earth to form a low-beryllium copper alloy component with the following mass percentages: Be 0.9 wt%, Co 1.0 wt%, Cr 0.5 wt%, Zr 0.15 wt%, Ag 0.5 wt%, mixed rare earth (lanthanum and cerium) 0.05 wt%, and the balance is Cu;

[0052] 2) Use a vacuum induction furnace for melting. Raise the temperature to 1250 °C until all the raw materials are melted, hold for 5 min, adjust the power of the melting furnace up and down 5 times to make the raw materials melt evenly, and let it stand for 10 min;

[0053] 3) Gas atomization to make powder: Raise the temperature to make the copper alloy in a molten state, pour it out of the furnace and into the gas atomizer. The pouring temperature is 1500 °C, the gas atomization pressure is 30 MPa, the gas atomization gas source is argon or nitrogen, and metal powder is obtained by gas atomization;

[0054] 4) Hot isostatic pressing sintering: Ball mill the proportioned metal powder (200 min, rotation speed 30 r / min), then transfer it into a hot isostatic pressing die sleeve. The sintering temperature is 850 °C, the pressing pressure is 50 MPa, hold for 30 min, and sinter to obtain a low-beryllium copper alloy blank;

[0055] 5) Forging: Under the condition of 750 - 850 °C, perform ring forging and ring rolling on the sintered blank, and the forging deformation rate is 60%;

[0056] 6) Solution aging treatment: Heat the forged ring workpiece to 900 °C, hold for 60 min, and then perform quenching treatment. Perform aging treatment on the quenched workpiece: The aging temperature is 450 °C, hold for 200 min, and cool to room temperature to obtain a low-beryllium copper alloy ring workpiece.

[0057] Compared with Example 2, the properties of the obtained low-beryllium copper alloy ring workpiece are as follows: the compactness of the hot isostatic pressing process product is further improved, the hardness is 405 HV, and the tensile strength is 1305 MPa; the conductivity shows a slight increase, being 48.3% IACS; the average grain size changes little, about 10-15 μm.

[0058] Example 4

[0059] The preparation method of the low-beryllium multi-component copper alloy for the mold includes the following steps:

[0060] 1) Weigh electrolytic copper, beryllium copper master alloy (Cu-2.0Be), cobalt particles, chromium copper alloy (Cu-5.0Cr), pure zirconium particles, pure silver particles, and mixed rare earths to form a low-beryllium copper alloy component with the following mass percentages: Be 0.9 wt%, Co 1.0 wt%, Cr 0.5 wt%, Zr 0.15 wt%, Ag 0.5 wt%, mixed rare earths (lanthanum and cerium) 0.05 wt%, and the balance is Cu;

[0061] 2) Use a vacuum induction furnace for melting. Raise the temperature to 1250 °C until all the raw materials are melted, hold for 5 min, adjust the power of the melting furnace up and down 5 times to make the raw materials melt evenly, and let it stand for 10 min;

[0062] 3) Gas atomization to make powder: Raise the temperature to make the copper alloy in a molten state, pour it out of the furnace and enter the gas atomizer. The pouring temperature is 1500 °C, the gas atomization pressure is 30 MPa, the gas atomization gas source is argon or nitrogen, and metal powder is obtained by gas atomization;

[0063] 4) SPS hot pressing forming: Grind the proportioned metal powder (200 min, rotation speed 30 r / min), then transfer it into an SPS graphite mold, quickly raise the temperature to 800 °C, the pressing pressure is 50 MPa, hold for 5 min, and sinter to obtain a low-beryllium copper alloy blank;

[0064] 6) Forging: Under the condition of 750-850 °C, perform ring forging and ring rolling on the sintered blank, and the forging deformation rate is 60%;

[0065] 7) Solution aging treatment: Raise the temperature of the forged ring workpiece to 900 °C, hold for 60 min and then perform quenching treatment. Perform aging treatment on the quenched workpiece: the aging temperature is 450 °C, hold for 200 min, and cool to room temperature to obtain a low-beryllium copper alloy ring workpiece.

[0066] Compared with Example 3, the SPS sample has the characteristics of good compactness and fine grains. The properties of the obtained low-beryllium copper alloy ring workpiece are as follows: the hardness is slightly increased to 421 HV, and the tensile strength is 1293 MPa; the conductivity is slightly decreased to 44.9% IACS; the average grain size is decreased to about 9 μm. (See Figure 1 -b)

[0067] Comparative Example 1

[0068] The preparation method of the low-beryllium multi-component copper alloy for the mold includes the following steps:

[0069] 1) Weigh electrolytic copper, beryllium copper master alloy, nickel copper alloy, silver copper alloy and mixed rare earths to form a low-beryllium copper alloy component with the following mass percentages: Be 0.9 wt%, Ni 1.0 wt%, Ag 0.5 wt%, mixed rare earths (lanthanum and cerium) 0.035 wt%, and the balance is Cu;

[0070] 2) Use a vacuum induction furnace for melting. Raise the temperature to 1250 °C until the alloy is completely melted, hold for 5 minutes, adjust the power of the melting furnace up and down 5 times to make the raw materials melt evenly. After standing for 10 minutes, cast the mold to obtain an ingot.

[0071] 3) Solution aging treatment: Heat the blank to 900 °C, hold for 60 minutes and then perform quenching treatment; perform aging treatment on the quenched workpiece: the aging temperature is 450 °C, hold for 200 minutes, and cool to room temperature to obtain a low-beryllium copper alloy ring workpiece.

[0072] The measured properties of the low-beryllium copper alloy ring workpiece are as follows: hardness 210 HV, tensile strength 526 MPa, conductivity 50.5% IACS; the average grain size is 20 - 50 μm, the grain size is uneven; the second-phase size is large, and there is nickel-phase enrichment.

[0073] Comparative Example 2

[0074] The preparation method of the low-beryllium multi-component copper alloy for the mold includes the following steps:

[0075] 1) Weigh electrolytic copper, beryllium copper master alloy, nickel copper alloy, silver copper alloy and mixed rare earths to form a low-beryllium copper alloy component with the following mass percentages: Be 0.9 wt%, Ni 1.0 wt%, Cr 0.5 wt%, Zr 0.15 wt%, Ag 0.5 wt%, mixed rare earths (lanthanum and cerium) 0.035 wt%, and the balance is Cu;

[0076] 2) Use a vacuum induction furnace for melting. Raise the temperature to 1250 °C until the alloy is completely melted, hold for 5 minutes, adjust the power of the melting furnace up and down 5 times to make the raw materials melt evenly. After standing for 10 minutes, cast the mold to obtain an ingot;

[0077] 3) Solution aging treatment: Heat the blank to 900 °C, hold for 60 min and then perform quenching treatment; perform aging treatment on the quenched workpiece: the aging temperature is 450 °C, hold for 200 min, and cool to room temperature to obtain a low-beryllium copper alloy ring workpiece;

[0078] The properties of the low-beryllium copper alloy ring workpiece are: hardness 280 HV, tensile strength 765 MPa, conductivity 53.1% IACS; the average grain size is 20 - 50 μm, and the grain size is uneven; the second-phase size is relatively large, and there is nickel-phase enrichment (see Figure 1 -a).

[0079] Comparative Example 3

[0080] The preparation method of the low-beryllium multi-component copper alloy for the mold is as follows:

[0081] 1) Weigh electrolytic copper, beryllium copper master alloy (Cu-2.0Be), nickel copper alloy, silver copper alloy, and mixed rare earth to form a low-beryllium copper alloy component with the following mass percentages: Be 0.9 wt%, Ni 1.0 wt%, Ag 0.5 wt%, mixed rare earth (lanthanum and cerium) 0.035 wt%, and the balance is Cu;

[0082] 2) Use a vacuum induction furnace for melting, raise the temperature to 1250 °C until all the raw materials are melted, hold for 5 min, adjust the power of the melting furnace up and down 5 times to make the raw materials melt evenly, and stand for 10 min;

[0083] 3) Gas atomization to make powder: Raise the temperature to make the copper alloy in a molten state, discharge it into the gas atomizer, the discharge temperature is 1500 °C, the gas atomization pressure is 30 MPa, the gas atomization gas source is argon or nitrogen, and metal powder is obtained by gas atomization;

[0084] 4) Die pressing to make blank: Ball mill the proportioned metal powder (200 min, rotation speed 30 r / min), and then transfer it to a mold for die pressing (400 MPa) to prepare a cold blank;

[0085] 5) Sintering: Put the cold blank into a sintering furnace, use hydrogen as the protective gas, the sintering temperature is 930 °C, hold for 25 min, and sinter to obtain a low-beryllium copper alloy blank;

[0086] 6) Solution aging treatment: Heat the blank to 900 °C, hold for 60 min and then perform quenching treatment. Perform aging treatment on the quenched workpiece: the aging temperature is 450 °C, hold for 200 min, and cool to room temperature to obtain a low-beryllium copper alloy.

[0087] This embodiment adopts the powder metallurgy process, and the properties of the obtained low-beryllium copper alloy are as follows: the hardness is 295 HV, the tensile strength is 824 MPa, and the conductivity is 51.7% IACS; the grain size is uniform and significantly refined, with an average size of 10 μm, which is because the powder metallurgy process effectively regulates the grain size of the copper alloy; the size of the second phase is reduced and the distribution is more uniform.

[0088] It can be seen from Example 1 and Comparative Examples 1-3 that in Example 1, Cr and Zr elements are added simultaneously and the process of gas atomization-sintering-forging is adopted, and the strength of the obtained low-beryllium copper alloy ring workpiece is improved. The reasons are as follows: Example 1 combines the age hardening of Cr element and the fine grain strengthening of the gas atomization-sintering powder metallurgy process; the forging treatment has a strengthening effect of work hardening on the alloy, and at the same time, the forging treatment refines the second phase of the alloy, introduces twins and dislocation defects, which can be used as the nucleation cores for solution aging and improve the solution aging strengthening effect of Be element and Cr element.

[0089] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Low-beryllium multi-component copper alloy for mold, Characterized in that, It comprises elements in the following mass percentages: Be 0.5~1.5wt%, Ni 0.8~1.5wt%, Cr 0.3~1.0wt%, Zr 0.1~0.25wt%, Ag 0.05~0.5wt%, rare earth 0.01~0.1wt%, and the balance is Cu; the ratio of Cr element to Zr element is 3:1 - 5:1; the hardness is 346 - 421HV, the tensile strength is 1050 - 1305MPa; the conductivity is 44.9 - 50.9%IACS.

2. Preparation method of the low-beryllium multi-component copper alloy for mold according to claim 1, Characterized in that, It comprises the following steps: (1) Weigh the raw materials of low-beryllium copper alloy, melt them and then atomize them by gas to obtain metal powder; (2) Sinter and densify the metal powder to obtain a low-beryllium copper alloy blank; (3) Forge, solutionize and age the low-beryllium copper alloy blank to obtain a low-beryllium copper alloy.

3. According to the preparation method described in claim 2, Characterized in that, In step (1), the method of atomizing by gas: after the raw materials are melted, the temperature is raised to the molten state, and then it is discharged into the gas atomizer. The discharging temperature is 1300~1700℃, the gas atomization pressure is 10~50MPa, the gas source is argon or nitrogen, and the metal powder is obtained by gas atomization.

4. According to the preparation method described in claim 2, Characterized in that, In step (1), the melting method: load the raw materials of low-beryllium copper alloy into the melting furnace, raise the temperature of the melting furnace to 1200~1500℃ until all the alloy is melted, keep it warm for 5~10min, adjust the power of the melting furnace up and down 3~5 times to make the raw materials melt evenly, and then let it stand for 5~10min.

5. According to the preparation method described in claim 2, Characterized in that, In step (2), the sintering method is die pressing blank - sintering, spark plasma sintering or hot isostatic pressing sintering.

6. According to the preparation method described in claim 5, Characterized in that, The specific method of die pressing blank - sintering is: transfer the metal powder into a mold or a cold isostatic pressing mold sleeve, press it under a pressure of 300~500MPa to prepare a cold blank; put the cold blank into a sintering furnace, and sinter it in a vacuum or hydrogen atmosphere to obtain a low-beryllium copper alloy blank. The sintering temperature is 750~1000℃, and the holding time is 5~300min.

7. According to the preparation method described in claim 5, Characterized in that, The specific method of spark plasma sintering is: transfer the metal powder into a graphite mold, under a vacuum and a pressure of 5 - 80MPa, raise the temperature to 750 - 980℃, and the holding time is 3~60min.

8. According to the preparation method described in claim 5, Characterized in that, The specific method of hot isostatic pressing sintering is: transfer the metal powder into a closed metal mold sleeve for hot isostatic pressing, under a pressure of 10 - 70MPa, raise the temperature to 800 - 950℃, and the holding time is 15~120min.

9. According to the preparation method described in claim 2, Characterized in that, In step (3), the forging method is as follows: at 750 - 850 °C, perform ring forging and ring rolling on the sintered blank, with a forging deformation rate greater than 50% to obtain a ring-shaped workpiece; the solution treatment and aging treatment methods are as follows: heat the forged workpiece to 760 - 950 °C, hold for 30 min - 3 h and then perform quenching treatment, and perform aging treatment on the quenched workpiece, with the aging temperature being 350 - 500 °C, holding for 2 - 6 h, and cooling to room temperature to obtain a low-beryllium copper alloy.

10. According to the preparation method described in claims 2, 5, 6, 7 or 8, characterized in that in step (2), first put the metal powder into a nodular can, select grinding balls with a diameter of 12 - 20 mm, a ball-to-powder ratio of 5 - 10:1, ball mill and mix the materials for 1 - 4 h at a rotational speed of 20 - 45 r / min, and then perform sintering densification treatment.

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