High-specific-gravity high-toughness tungsten-nickel-copper alloy material and preparation method thereof

Abstract

The invention provides a high-specific-gravity high-toughness tungsten-nickel-copper alloy material and a preparation method thereof. The material comprises the following components in percentage by mass: 6-15% of nickel (Ni); copper (Cu): 2-5%; the manganese (Mn) accounts for 2-5%, and the balance is tungsten and inevitable impurities. The preparation method comprises the following steps: preparing materials (pure tungsten, pure nickel, pure copper and pure manganese powder), mixing the powder, pressing, sintering, and carrying out recrystallization annealing heat treatment. By adding the strengthening element manganese, combining the gradient particle size ratio and enhancing interface bonding, the high specific gravity and high strength of the material are kept, meanwhile, excellent toughness can be kept, and the material is suitable for aerospace gyroscope rotors and balance weight parts, electronic industry precise instrument parts, medical instrument ray shielding materials and national defense military industry kinetic energy armor-piercing weapon parts.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal materials technology, specifically relating to a high-density, high-strength, and high-toughness tungsten-nickel-copper material and its preparation method. Background Technology

[0002] China has the world's largest tungsten reserves. Of the approximately 3.3 million tons of known tungsten resources globally, 1.9 million tons are located in my country, accounting for about 58% of the world's total. The theoretical density of tungsten is as high as 19.35 g / cm³. 3 Tungsten-copper alloys not only possess the characteristics of high density and high hardness, but also the excellent properties of electrical and thermal conductivity, making them widely used in various fields such as electrical contacts, electronic packaging, and military applications. Furthermore, tungsten alloys are a class of alloy systems composed mainly of tungsten (80%–98% tungsten content) with small amounts of elements such as Ni, Cu, Fe, Co, Mo, and Cr. They are characterized by high density, high melting point, and good plasticity, making them ideal alloy liner materials. In recent years, based on the high melting point and difficult metallurgical bonding characteristics of high-density tungsten, scientists have used powder metallurgy technology to study the influence of adding dissimilar low-melting-point elements (such as Ni, Fe, and Co) on grain boundary fusion, attempting to solve the interfacial transition problem of dissimilar material connection / fusion. This has led to the development of a series of high-density tungsten-nickel-copper powder metallurgy materials, meeting some of the needs of industrial equipment. However, while maintaining material density and high strength, the elongation remains relatively low, generally not exceeding 15%. This performance "shortcoming" poses significant safety hazards to components made from materials obtained using tungsten-nickel-copper powder metallurgy technology. Furthermore, in the field of tungsten-nickel-copper propellant liner applications for national defense, it also suffers from large jet dispersion, becoming a major bottleneck restricting the development of this material.

[0003] Therefore, based on the above-mentioned problems, this invention studies tungsten-nickel-copper alloy materials and has made breakthrough progress. Summary of the Invention

[0004] To overcome the problems in the prior art, this invention is based on a meticulous study of the W-Ni-Cu powder metallurgy preparation process. Specifically, by adding interfacial catalytic elements through alloying and optimizing the sintering process, the chemical composition of the interface is controlled to improve distribution uniformity and reduce segregation. Simultaneously, interfacial bonding is enhanced, allowing the single-phase solid solution region at the interface to remain continuous and effective, thereby improving interfacial bonding strength and toughness. Ultimately, a high-density, high-strength, and high-toughness tungsten-nickel-copper powder metallurgy material is obtained, enabling its application in electronics, aerospace, aviation, and weaponry.

[0005] The purpose of this invention is to provide a high-density, high-strength, and high-toughness tungsten-nickel-copper alloy material and its preparation method, which is achieved through the following technical solutions.

[0006] A high-density, high-strength, and high-toughness tungsten-nickel-copper alloy material, characterized in that the material composition, by mass percentage, includes: nickel (Ni): 6~15%; copper (Cu): 2~5%; manganese (Mn): 2~5%, with the balance being tungsten and unavoidable impurities, wherein the tungsten is pure tungsten powder with two particle sizes: 270-300 mesh (48-53μm) and 600-650 mesh (21-23μm);

[0007] Except for pure tungsten powder, the particle size of the other components is 600-650 mesh.

[0008] The high-density, high-strength, and high-toughness tungsten-nickel-copper alloy material of the present invention is characterized in that the tensile strength of the material is 800-950 MPa, and the elongation can reach more than 20%.

[0009] Furthermore, the total mass percentage of the unavoidable impurities is ≤0.5%;

[0010] Furthermore, the preferred addition ratio of the two particle size grades of pure tungsten powder (270-300 mesh and 600-650 mesh, respectively) is 2:1-3:2;

[0011] Furthermore, in the tungsten-nickel-copper alloy of the present invention, the preferred composition is nickel (Ni): 8-13%; copper (Cu): 2.5-4.5%; manganese (Mn): 2-4.5%.

[0012] Furthermore, in the tungsten-nickel-copper alloy of the present invention, the ratio of Ni to Cu is 3:2-3:1.

[0013] The present invention also provides a method for preparing the above-mentioned high-density, high-strength, and high-toughness tungsten-nickel-copper alloy material, the steps of which include:

[0014] (1) Ingredients: Weigh pure tungsten, pure copper, pure nickel and pure manganese powders according to the above composition ratio as raw materials. The particle size of pure tungsten powder is two grades, and the particle size of the other components is 600-650 mesh.

[0015] (2) Powder mixing: The weighed W, Ni, Cu, Mn powders from step (1) and the ball milling media are loaded into a cemented carbide WC ball milling jar at a ball-to-material ratio of 10:1. The ball milling media used are tungsten balls. Anhydrous ethanol is added to the jar as a wet milling medium and wet milling is performed to obtain a uniformly mixed powder.

[0016] (3) Pressing: Add binder to the powder mixture obtained in step (2), and then press it into a compact on a cold isostatic press;

[0017] (4) Sintering: The pressed blank after step (3) is pre-sintered and liquid-phase sintered under a hydrogen atmosphere to obtain a sintered alloy;

[0018] (5) Heat treatment: The sintered alloy from step (4) is subjected to recrystallization annealing under an argon atmosphere to obtain the target alloy material.

[0019] In step (1), the pure tungsten powder has two particle sizes: 270-300 mesh (48-53 μm) and 600-650 mesh (21-23 μm). The material composition by mass percentage is: nickel (Ni): 6-15%; copper (Cu): 2-5%; manganese (Mn): 2-5%, with the balance being tungsten and unavoidable impurities. Furthermore, the ratio of Ni to Cu is 3:2-3:1.

[0020] In step (2), the wet milling is carried out under an inert atmosphere of first evacuating and then filling with argon. The ball mill speed is 300~400 rpm and the ball milling time is 5h~10h. After the wet milling is completed, the powder is taken out and placed in a vacuum drying oven at 80℃ for 1~2h to dry and remove the wet milling medium.

[0021] In step (3), the binder is stearic acid or its salt (such as stearic acid or zinc stearate), the amount added is 1.5-2 wt.% relative to the mass of the added metal powder, the molding is cold isostatic pressing, the molding pressure is 300-400 MPa, and the holding time is 5-8 min.

[0022] In step (4), the purpose of pre-sintering is to remove fusible and volatile substances from the compact. The pre-sintering conditions are to heat the compact to 600℃-800℃ and hold it for 0.5-1h. After pre-sintering, the binder will undergo thermal decomposition to achieve degreasing. The final sintering process involves heating the compact to 1500℃~1550℃ and holding it for 2~2.5h for final liquid-phase sintering.

[0023] In step (5), the recrystallization annealing condition is to heat the sintered sample to 1350℃~1380℃ and hold it for 2~2.5h. Recrystallization annealing can alleviate stress concentration at the interface, promote interdiffusion of elements at the interface, thereby improving the interfacial bonding force and reducing the risk of interface cracking during the service of the material.

[0024] The preparation method of this invention is mainly a powder metallurgy preparation process, which simply includes: weighing pure tungsten, pure copper, pure nickel and pure manganese powders according to the ratio, mixing the powders under vacuum, cold isostatic pressing, sintering under a protective atmosphere and recrystallization annealing, etc.

[0025] In addition, the particle size grades of the different metal powder materials of the present invention are shown in Table 1 below:

[0026] Table 1. Particle size grades of metal raw material powder in a high-density, high-strength, and high-toughness tungsten-nickel-copper alloy material.

[0027]

[0028] The main raw materials used in this invention have the following specifications: pure tungsten powder, 270-300 mesh and 600-650 mesh, purity ≥99.9wt%; pure nickel powder, 600-650 mesh, purity ≥99.9wt%; pure copper powder, 600-650 mesh, purity ≥99.9wt%; pure manganese powder, 600-650 mesh, purity ≥99.9wt%; and auxiliary materials are anhydrous ethanol and 1.5-2wt.% stearic acid or its salt. Furthermore, tungsten is easily oxidized at high temperatures; therefore, a protective atmosphere is required during powder mixing, sintering, and heat treatment.

[0029] In this invention, regarding the Ni element, since Ni has good wettability to W, adding Ni can achieve activated liquid phase sintering and improve toughness. If the addition amount is greater than 15%, the heat resistance and corrosion resistance of the alloy will decrease. If the addition amount is less than 6%, the sintering densification process of the alloy will be hindered, which will significantly reduce the strength and toughness of the alloy.

[0030] For Cu, the addition of Cu has a solid solution strengthening effect on the formation of alloy materials, and can control the solubility of W in Ni, preventing the formation of nickel-tungsten brittle compounds. If the addition amount is greater than 5%, the strength and toughness of copper itself are lower than those of nickel. Excessive copper will dilute the concentration of nickel in the binder phase, weaken the binder phase, and reduce the hardness, strength and elongation of the alloy. If it is less than 2%, it will increase the sintering temperature, make sintering densification difficult, and make the brittle phase more likely to form, resulting in the alloy becoming hard and brittle and having poor machinability.

[0031] Furthermore, the preferred ratio of Ni to Cu is 3:2 to 3:1. According to existing research and experimental practice, tungsten-nickel-copper alloys within this ratio range achieve a good balance among various properties such as strength, toughness, electrical conductivity, and thermal conductivity.

[0032] In this invention, regarding the addition of manganese, on the one hand, the atomic radii of γ-Mn and Ni differ by less than 15%, and both have a face-centered cubic structure, which can form an infinite solid solution. When some manganese is dissolved in the binder phase of the alloy, it will play a role in solid solution strengthening of the binder phase. On the other hand, when manganese is added to the system, it reacts with oxygen and sulfur, which are impurities, to produce corresponding oxides and sulfides. This can reduce the segregation of impurity elements at the interface, thus purifying the interface and improving the interfacial bonding strength.

[0033] In addition, given the role of the strengthening element manganese (Mn), its content is preferably controlled at 2-5%. However, it should be noted that when the manganese content is below 2%, the effect of interface purification cannot be achieved; when the manganese content is above 5%, the microstructure distribution is uneven and the mechanical properties of the alloy are significantly reduced. This is mainly due to the increased manganese content, which limits the solubility of tungsten in the binder phase.

[0034] Beneficial technical effects of the present invention:

[0035] The high-density, high-strength, and high-toughness tungsten-nickel-copper alloy material provided by the present invention has a high specific gravity derived from the high specific gravity of tungsten (19.35 g / cm³) in its alloy composition. 3 Using copper, nickel, and manganese as the matrix, and combining their gradient particle size ratio to control the volume complementarity between powder particles to achieve high density, the addition of solid solution strengthening elements such as copper, nickel, and manganese, along with sintering process optimization, eliminates the adverse effects of interfacial impurities such as oxygen and sulfur. Furthermore, high-temperature sintering and subsequent heat treatment control the diffusion interface between dissimilar elements, resulting in uniform distribution of interfacial elements and continuous and effective single-phase solid solution regions at the interface. This improves interfacial strength while inhibiting harmful interfacial reactions, thereby enhancing interfacial toughness and yielding high-density, high-toughness tungsten-nickel-copper powder metallurgy materials.

[0036] The preparation method of the high-density, high-strength, and high-toughness tungsten-nickel-copper material provided by this invention mainly adopts powder metallurgy technology. It enhances the interfacial bonding strength by adding strengthening elements, combining gradient particle size distribution, and recrystallization annealing to improve the interfacial state. This material maintains high elongation and high strength, with a tensile strength of 800-950 MPa and an elongation exceeding 20%. Applying this material to the field of tungsten-nickel-copper propellant liner applications can increase the jet penetration depth. Because the alloy material obtained by this invention maintains both high density and high strength while also possessing excellent toughness, it is suitable for aerospace gyroscope rotors and counterweights, precision instrument parts in the electronics industry, radiation shielding materials for medical devices, and components for kinetic energy penetrating weapons in the defense industry. Detailed Implementation

[0037] The present invention will now be described in detail with reference to specific embodiments.

[0038] The method for preparing the high-density, high-strength, and high-toughness tungsten-nickel-copper material of the present invention includes the following detailed steps:

[0039] (1) Ingredients: Weigh pure tungsten, pure nickel, pure copper and pure manganese powders according to the above composition mass ratio as raw materials, and the addition ratio of two different particle size grades (270-300 mesh and 600-650 mesh) of tungsten powder is 3:2-3:1.

[0040] (2) Powder mixing: The powder and grinding media are loaded into a cemented carbide WC ball milling jar at a ball-to-material ratio of 10:1. The grinding media used are tungsten balls, with anhydrous ethanol added as wet grinding media. The ball milling is carried out under an inert atmosphere of first evacuating and then filling with argon. The ball mill speed is 300~400 rpm and the ball milling time is 5h~10h. After wet grinding is completed, the powder is taken out and placed in a vacuum drying oven at 80℃ for 1~2h to dry and remove the wet grinding media.

[0041] (3) Pressing: Add 1.5-2 wt.% of stearic acid or its salt as a binder to the uniformly mixed powder, and then press it on a cold isostatic press. The pressing pressure is 300-400 MPa and the holding time is 5-8 min.

[0042] (4) Sintering: Pre-sintering treatment is carried out in a hydrogen atmosphere. The compact is heated to 600℃-800℃ and held for 0.5-1h. Then the compact is heated to 1500℃~1550℃ and held for 2~2.5h for final liquid phase sintering. The sample is taken out after furnace cooling to room temperature.

[0043] (5) Heat treatment: Heat treatment is carried out in an argon atmosphere. The sample is heated to 1350℃~1380℃ and held for 2-2.5h to achieve recrystallization annealing.

[0044] The following detailed description is provided through specific embodiments:

[0045] Example 1

[0046] The specific process is as follows: Four samples 1-1 to 1-4 are prepared according to the composition in Table 2, and a gradient particle size ratio is adopted. The particle size of pure tungsten powder is 300 mesh and 650 mesh, and the particle size of pure copper, pure nickel and pure manganese powder is 650 mesh. The addition ratio of the two particle size grades of pure tungsten powder is 2:1.

[0047] Table 2. Composition of each sample in Example 1 (wt.%)

[0048]

[0049] Weighed metal powders and tungsten balls were added to a cemented carbide WC ball milling jar. Anhydrous ethanol was added, and the jar was evacuated and filled with argon gas. The jar was ball-milled at 300 rpm for 10 hours. The powder was then removed and dried. The powder was pressed into a blank at 300 MPa for 5 minutes using a cold isostatic press. The blank was then pre-sintered at 800℃ for 1 hour under a hydrogen atmosphere, followed by liquid-phase sintering at 1500℃ for 2.5 hours. After furnace cooling, the sample was removed and then recrystallized and annealed at 1350℃ for 2.5 hours under an argon atmosphere. The properties of the prepared samples are shown in Table 3.

[0050] Table 3 Performance of each sample in Example 1

[0051]

[0052] Example 2

[0053] The specific process is as follows: Four samples 2-1 to 2-4 were prepared according to the composition in Table 4, and a gradient particle size ratio was adopted. The particle size of pure tungsten powder was 300 mesh and 650 mesh, and the particle size of pure copper, pure nickel and pure manganese powder was 650 mesh. The addition ratio of the two particle size grades of pure tungsten powder was 3:2.

[0054] Table 4. Composition of each sample in Example 2 (wt.%)

[0055]

[0056] Weighed metal powders and tungsten balls were added to a cemented carbide WC ball milling jar. Anhydrous ethanol was added, and the jar was evacuated and filled with argon gas. The jar was ball-milled at 300 rpm for 10 hours. The powder was then removed and dried. The powder was pressed into a blank at 300 MPa for 5 minutes using a cold isostatic press. The blank was then pre-sintered at 800℃ for 1 hour under a hydrogen atmosphere, followed by liquid-phase sintering at 1500℃ for 2.5 hours. After furnace cooling, the sample was removed and then recrystallized and annealed at 1350℃ for 2.5 hours under an argon atmosphere. The properties of the prepared samples are shown in Table 5.

[0057] Table 5 Performance of each sample in Example 2

[0058]

[0059] Example 3

[0060] The specific process is as follows: Four samples 3-1 to 3-4 are prepared according to the composition in Table 6, and a gradient particle size ratio is adopted. The particle size of pure tungsten powder is 300 mesh and 650 mesh, and the particle size of pure copper, pure nickel and pure manganese powder is 650 mesh. The addition ratio of the two particle size grades of pure tungsten powder is 2:1.

[0061] Table 6. Composition of each sample in Example 3 (wt.%)

[0062]

[0063] Weighed metal powders and tungsten ball milling media were added to a cemented carbide WC ball milling jar. Anhydrous ethanol was added, and the jar was evacuated and filled with argon gas. The jar was milled at 400 rpm for 5 hours. The powder was then removed and dried. The powder was pressed into a blank at 300 MPa for 5 minutes on a hydraulic press. The blank was then pre-sintered at 700℃ for 1 hour in a hydrogen atmosphere, followed by liquid-phase sintering at 1550℃ for 2 hours. After furnace cooling, the sample was removed and then recrystallized at 1380℃ for 2 hours in an argon atmosphere. The properties of the prepared product are shown in Table 7.

[0064] Table 7 Performance of each sample in Example 3

[0065]

[0066] The above embodiments and tables show the composition of the alloy materials and the properties of the obtained alloy materials. As can be seen from the above, when the component ratios and gradient particle size ratios of the above embodiments are within the scope of the present invention, the tensile strength of the obtained high-density, high-strength, and high-toughness tungsten-nickel-copper alloy material samples are all above 800 MPa, and the elongation is above 20%. It can be seen that the alloy materials obtained by the present invention have relatively high strength and toughness.

[0067] Comparative Example 1

[0068] This comparative example uses a single particle size formulation. The specific preparation process is as follows: The powders are formulated according to the components in Table 8, where the pure tungsten powder, pure copper powder, and pure nickel powder all have a particle size of 650 mesh. The powders and milling media are added to a ball mill jar, anhydrous ethanol is added, a vacuum is drawn, and argon gas is introduced. The jar is then ball-milled at 300 rpm for 10 hours. The powder is then removed and dried. The powder is pressed into a blank at 300 MPa for 5 minutes on a hydraulic press. The blank is then heated to 1500℃ at a rate of 5℃ / min under a hydrogen atmosphere and held for 2.5 hours for liquid-phase sintering. After furnace cooling, the sample is removed and annealed at 1350℃ for 2.5 hours under an argon atmosphere.

[0069] Table 8. Composition of each sample in the comparative examples (wt.%)

[0070]

[0071] Table 9 Performance of each sample in the comparative examples

[0072]

[0073] Examples 1-3 and Comparative Example 1 above illustrate that the factors affecting the performance of alloy materials lie in the differences in alloy preparation process parameters and changes in composition. The comparative example, whose component content and gradient particle size distribution are outside the scope of this invention, still exhibits significantly lower strength and toughness when sintered using the same process as this invention. For example, sample 4-1, despite having a tensile strength higher than 800 MPa, has a much lower elongation. This is mainly because the strength and toughness of tungsten alloys are highly sensitive to residual porosity; when the residual porosity reaches 1%-1.5%, the alloy becomes completely brittle. Furthermore, the comparative example alloy material is formed by pressing and sintering a single-particle-size powder (without gradient particle size distribution), resulting in a significantly lower density than the alloys in the embodiments of this invention. Additionally, the comparative example did not add the strengthening element manganese, leading to impurity element segregation at the alloy interface, resulting in low interface strength and a direct adverse effect on alloy performance. In contrast, the embodiments of this invention, by adding strengthening elements, combining gradient particle size distribution, and controlling the recrystallization annealing heat treatment, ultimately obtained a high-density tungsten-nickel-copper material with excellent strength and toughness.

[0074] The above description is merely a preferred embodiment of the present invention and is not limited to the invention. It should be noted that those skilled in the art can make other equivalent improvements based on the technical teachings provided by the present invention, all of which can achieve the purpose of the present invention and should be considered within the scope of protection of the present invention.

Claims

1. A high-density, high-strength, high-toughness tungsten-nickel-copper alloy material, characterized in that, The material composition, by mass percentage, includes: nickel: 6-15%; copper: 2-5%; manganese: 2-5%, with the balance being tungsten and unavoidable impurities. The pure tungsten powder has two particle sizes: 270-300 mesh and 600-650 mesh.

2. The high-density, high-strength, high-toughness tungsten-nickel-copper alloy material according to claim 1, characterized in that, The total mass percentage of the unavoidable impurities is ≤0.5%.

3. The high-density, high-strength, high-toughness tungsten-nickel-copper alloy material according to claim 1, characterized in that, In the tungsten-nickel-copper alloy, the material composition by mass percentage is nickel: 8~13%; Copper: 2.5~4.5%; Manganese: 2~4.5%.

4. The high-density, high-strength, high-toughness tungsten-nickel-copper alloy material according to claim 1, characterized in that, The addition ratio of the two particle sizes of the tungsten powder is 3:2 to 2:

1.

5. The high-density, high-strength, high-toughness tungsten-nickel-copper alloy material according to claim 1, characterized in that, The ratio of nickel to copper in the composition ranges from 3:2 to 3:

1.

6. The high-density, high-strength, high-toughness tungsten-nickel-copper alloy material according to claim 1, characterized in that, The alloy material has a tensile strength of 800-950 MPa and an elongation of over 20%.

7. A method for preparing a high-density, high-strength, high-toughness tungsten-nickel-copper alloy material as described in any one of claims 1-6, characterized in that, The method steps include: (1) Ingredients: Weigh pure tungsten, pure copper, pure nickel and pure manganese powders according to the above composition ratio as raw materials. The particle size of pure tungsten powder is two grades, and the particle size of other raw materials is 600-650 mesh. (2) Powder mixing: The weighed W, Ni, Cu, Mn powders from step (1) and the ball milling media are loaded into a cemented carbide WC ball milling jar at a ball-to-material ratio of 10:

1. The ball milling media used are tungsten balls. Anhydrous ethanol is added to the jar as a wet milling medium and wet milling is performed to obtain a uniformly mixed powder. (3) Pressing: Add binder to the powder mixture obtained in step (2), and then press it into a compact on a cold isostatic press; (4) Sintering: The pressed blank after step (3) is pre-sintered and liquid-phase sintered under a hydrogen atmosphere to obtain a sintered alloy; (5) Heat treatment: The sintered alloy from step (4) is subjected to recrystallization annealing under an argon atmosphere to obtain the target alloy material.

8. The preparation method according to claim 7, characterized in that, The pure tungsten powder has particle sizes of 270-300 mesh and 600-650 mesh, respectively, with a ratio of 3:2 to 2:

1.

9. The preparation method according to claim 7, characterized in that, In step (3), the binder is stearic acid or its salt, and the amount added is 1.5-2 wt.% relative to the mass of the added metal powder.

10. The preparation method according to claim 7, characterized in that, In step (4), the pre-sintering treatment conditions are to heat the compact to 600℃-800℃ and hold it for 0.5-1h, and the liquid phase sintering treatment is to heat the compact to 1500℃~1550℃ and hold it for 2~2.5h; in step (5), the recrystallization annealing conditions are to heat the sintered sample to 1350℃~1380℃ and hold it for 2~2.5h.

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