Method for producing high melting point metal member

Abstract

The application discloses a high-melting-point metal component preparation method, which comprises the following steps: S10, a high-melting-point metal component blank is prepared by adopting an SLM method; and S20, the high-melting-point metal component blank is subjected to improved heat treatment, wherein the improved heat treatment is heat treatment of the high-melting-point metal component blank by adopting a high-temperature high-pressure long-time mode, and plastic deformation of the high-melting-point metal component blank occurs when the improved heat treatment is performed, so as to obtain a high-melting-point metal component product; wherein the high temperature is not lower than 1450 DEG C, the high pressure is not lower than 25 MPa, and the heat treatment time is not shorter than 65 min. Thus, after the high-melting-point metal component blank prepared by the SLM method is subjected to the high-temperature high-pressure long-time improved heat treatment, the crystal of the component can be further refined, and the cracks generated in the SLM preparation process of the high-melting-point metal component blank can be healed in the improved heat treatment process, so that the internal defects of the component are reduced.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and specifically to a method for preparing high-melting-point metal components. Background Technology

[0002] Currently, high-melting-point metal components (generally referring to metals with melting points above 1500℃, such as tungsten, molybdenum, nickel-titanium alloys, etc.) are mainly prepared by methods such as spark plasma sintering (SPS), hot isostatic pressing (HIP), and selective laser melting (SLM).

[0003] However, due to the characteristics of high-melting-point metals, such as high melting point, high thermal conductivity, high melt viscosity, affinity for oxygen at high temperatures, and brittleness at room temperature, high-melting-point metal components prepared by the SLM method often exhibit porosity and cracks, and typically suffer from defects such as coarse grains and columnar crystals, severely affecting the mechanical properties of the high-melting-point metal components. This is because the SLM process involves a large temperature gradient, which not only leads to coarse grains but also to obvious grain orientation, resulting in an excessively high ductile-brittle transition temperature for high-melting-point metals. Furthermore, the accumulation of oxygen impurities at grain boundaries can weaken these boundaries, leading to crack formation. High-melting-point metal components prepared by the SPS method have lower density and poorer performance. High-intensity interphase (HIP) preparation of high-melting-point metal components is costly and also suffers from the problem of large grains.

[0004] Although the invention patent application CN120696441A discloses a method for closing cracks in SLM-prepared tungsten components based on SPS, which proposes to treat pure tungsten components prepared by SLM process with SPS to effectively close unavoidable microcracks in SLM pure tungsten components, this method cannot solve the problem of coarse grains in pure tungsten components prepared by SLM process. Summary of the Invention

[0005] The patent in the background technology describes a solution developed by the inventor to address problems such as cracking and coarse grains in the preparation of high-melting-point metals. However, this solution only solves the problem of cracking during the preparation of high-melting-point metals, and cannot solve the problem of coarse grains. During experiments preparing high-melting-point metal components, the inventor accidentally discovered that plastic deformation during heat treatment of the components could refine the grains after prolonged high-temperature, high-pressure heat treatment; conventional thinking holds that prolonged, high-temperature treatment leads to coarse grains. Based on this discovery, the inventor broke with conventional thinking and proposed a method for preparing high-melting-point metal components to solve the problems of cracking and coarse grains in the preparation process.

[0006] The method for preparing this high-melting-point metal component includes the following steps:

[0007] S10: High-melting-point metal component blanks are prepared using the SLM method;

[0008] S20: Improved heat treatment is applied to high-melting-point metal component blanks. The improved heat treatment involves heat treatment of the high-melting-point metal component blanks under high temperature, high pressure and long duration. During the improved heat treatment, the high-melting-point metal component blanks undergo plastic deformation to obtain finished high-melting-point metal components. The high temperature is not lower than 1450℃, the high pressure is not lower than 25MPa, and the heat treatment time is not less than 65min.

[0009] The reason for using the SLM method to prepare high-melting-point metal component blanks is that the inventors discovered that the SLM method can generate microstructures with high dislocation density and specific morphology under rapid melting and solidification conditions, and can achieve near-net-shape forming of complex components. This allows for high-temperature, high-pressure, long-term improvement heat treatment of the high-melting-point metal component blanks prepared by the SLM method, enabling the healing of cracks generated during the SLM preparation process and reducing internal defects in the components. However, if the SPS method is used to prepare high-melting-point metal component blanks, the resulting blanks have poor density, making it impossible to achieve crack healing and grain refinement through subsequent improvement heat treatment. Furthermore, in step S20, the high-temperature, high-pressure improvement heat treatment causes plastic deformation in the high-melting-point metal component blanks, healing internal cracks while simultaneously refining the grains of the high-melting-point metal component, achieving technical effects unexpected by those skilled in the art.

[0010] In some embodiments, in step S20, the amount of plastic deformation that causes the high-melting-point metal component blank to undergo plastic deformation during the improved heat treatment is 0.5% to 10%. This ensures that the high-melting-point metal component blank exhibits grain refinement after undergoing high-temperature and high-pressure improved heat treatment.

[0011] In some embodiments, step S20 includes step S21: before heating the high-melting-point metal component blank, the high-melting-point metal component blank is placed in a sealed container, and the outer periphery of the high-melting-point metal component blank in the container is filled with a powder that is chemically inert, thermally conductive, and has low electrical conductivity. This avoids a chemical reaction between the powder and the high-melting-point metal component, while ensuring uniform heat conduction, thereby reducing the thermal stress on the high-melting-point metal component blank during improved heat treatment and preventing cracking.

[0012] In some embodiments, in step S21, the chemical inertness of the powder filling the periphery of the high-melting-point metal component blank in the accommodating space is achieved by ensuring that it does not chemically react with the high-melting-point metal below 1500°C, and the thermal conductivity is achieved by ensuring that it has a thermal conductivity of 1~200 W·m. -1 ·K -1 Low conductivity, with conductivity below 10. -5 S / m.

[0013] In some embodiments, in step S21, the powder filling the outer periphery of the high-melting-point metal component blank in the accommodating space is made of alumina, silicon carbide, zirconium oxide, and alumina-like ceramic materials. This allows the powder to possess suitable chemical inertness, thermal conductivity, and low electrical conductivity; preferably, alumina powder is used to reduce manufacturing costs.

[0014] In some embodiments, in step S21, the particle size range of the powder filling the outer periphery of the high-melting-point metal component blank in the accommodating space is 1μm to 100μm. This not only ensures more uniform overall heating and faster temperature rise, but also facilitates demolding, avoiding the problem of difficulty in demolding due to finer particle size.

[0015] In some embodiments, the cooling method for improving heat treatment is natural cooling. This avoids grain growth in the high-melting-point metal component blank during cooling; moreover, because the temperature gradient and cooling rate are smaller in natural cooling, it helps to gradually release thermal stress, preventing new cracks or deformations caused by rapid cooling. This cooling method is similar to annealing after plastic deformation, allowing the microstructure in the high-melting-point metal component blank to fully recover and recrystallize, thereby obtaining a more stable fine-grained structure and improving the mechanical properties of the finished high-melting-point metal component.

[0016] In some embodiments, the container material is graphite. Because graphite has a melting point of 3850±50℃, excellent electrical conductivity and high-temperature stability, and is inexpensive and easily machinable, using high-melting-point graphite as a container for high-melting-point metal components ensures stable operation under high-temperature and high-current conditions, prevents contamination of the high-melting-point metal component blanks, guarantees the stability of the container during heat treatment, and reduces manufacturing costs. Furthermore, the good thermal conductivity of graphite containers ensures temperature uniformity of the high-melting-point metal component blanks during heat treatment and prevents them from sticking to the container during the heat treatment process.

[0017] In some embodiments, step S20 further includes step S22 after step S21: controlling the pressure of the accommodating space containing the high-melting-point metal component blank and the powder with chemical inertness, thermal conductivity, and low electrical conductivity to above 25 MPa. Pre-pressurizing to 25 MPa before heating allows the powder with chemical inertness, thermal conductivity, and low electrical conductivity to fully contact the high-melting-point metal component blank to be heated, resulting in more uniform heat conduction and facilitating uniform heating of the high-melting-point metal component blank subsequently. In addition, pre-pressurizing before heating avoids the need for rapid pressurization during the heating process, reducing the risk of stress concentration and crack propagation caused by thermal gradients.

[0018] In some embodiments, the container includes a female mold and a punch that are adapted to each other. The female mold has a cavity adapted to the punch, and the punch and the female mold together form an accommodating space. The pressure is an axial pressure along the axis of the female mold. Thus, the pressure in the accommodating space can be adjusted by the depth to which the punch is inserted into the cavity of the female mold, and the adjustment method is relatively convenient. Moreover, although the pressure is set along the axis of the female mold, a relatively uniform pressure can still be obtained because the high-melting-point metal component blank is coated with powder.

[0019] In some embodiments, step S20 further includes step S23 after step S22: first, evacuating the furnace cavity of the heat treatment furnace undergoing the improved heat treatment, and then introducing argon gas, controlling the vacuum level at 1.0~2.0×10⁻⁶. 3 mbar. This prevents oxidation of high-melting-point metal component blanks during the improved heat treatment process.

[0020] In some embodiments, step S20 further includes step S24 after step S23: controlling the heating rate of the furnace cavity of the heat treatment furnace at 100±10℃ / min, and / or increasing the pressure of the container space. This ensures that the high-melting-point metal component blank undergoes plastic deformation during improved heat treatment; moreover, using a heating rate of 100±10℃ / min allows the high-melting-point metal component blank to quickly reach the target temperature range, which helps reduce the risk of grain growth and avoids risks such as oxidation caused by prolonged high temperatures.

[0021] In some embodiments, in step S23, the vacuum level of the furnace cavity needs to reach 1~9.9×10⁻⁶ before argon gas is introduced. -2 mbar. This ensures that impurities in the furnace cavity are removed as thoroughly as possible, thus guaranteeing the effectiveness of the treatment.

[0022] In some embodiments, in step S23, the argon gas introduction rate is 2~10 L / min. An appropriate argon gas flow rate can continuously displace the gas in the chamber and stabilize the inert atmosphere. A flow rate that is too high or too low may result in insufficient displacement of the furnace atmosphere.

[0023] In some embodiments, in step S24, the pressure increase rate of the container's accommodating space is 0.5~2 MPa·min. -1 In the early stages of heating, the temperature is not high enough, and high-melting-point metals such as tungsten (W) with high ductile-brittle transition temperatures remain brittle. If the pressure is increased too quickly, new cracks may form. This application controls the pressure increase rate to 2 MPa·min. -1 The following steps can prevent the formation of new cracks.

[0024] The inventors, while researching how to induce plastic deformation in high-melting-point metal components during heat treatment, discovered that ultra-high temperature, ultra-high pressure, and long duration heat treatment can induce plastic deformation in these components. Therefore, to refine the grain size, the high temperature for heat treatment was limited to 1450–1500°C; the heat treatment time was limited to 65–90 min; and / or the heat treatment pressure was limited to 35 MPa–40 MPa.

[0025] When the high temperature is 1450~1500℃, the heat treatment time is 65min~90min, and the high pressure is 35MPa~40MPa, it can be ensured that the high melting point metal component blank undergoes plastic deformation during the improved heat treatment process. This not only allows the cracks generated in the high melting point metal component blank during the SLM method to heal during the improved heat treatment process, but also refines the grains of the high melting point metal component to obtain the finished high melting point metal component.

[0026] In some embodiments, the volume V of the high-melting-point metal component blank is less than 180 mm². 3 This ensures that the cracks inside the prepared high-melting-point metal component are healed, and that all the internal grains are refined. Attached Figure Description

[0027] Figure 1 This is a schematic flowchart of a method for preparing a high-melting-point metal component according to an embodiment of the present invention;

[0028] Figure 2 for Figure 1 A schematic diagram illustrating the specific implementation process of step S20 in the method for preparing high-melting-point metal components.

[0029] Figure 3 This is a schematic diagram showing the placement of the SPS sample;

[0030] Figure 4 Metallographic images of tungsten components; among them, Figure 4 Figure (a) shows a metallographic image of a tungsten component directly prepared using SLM; Figure 4Figure (b) shows the metallographic image of the tungsten component after SLM treatment and without deformation. Figure 4 Figure (c) in the figure is a metallographic image of a tungsten component that has undergone SLM-like treatment and deformation.

[0031] Figure 5 The image shows the EBSD (electron backscatter diffraction) analysis results of the tungsten component; among them, Figure 5 Figure (a) shows the EBSD analysis diagram of a tungsten component directly prepared by SLM; Figure 5 Figure (b) in the figure is an EBSD analysis diagram of a tungsten component that has undergone SLM-like treatment and deformation.

[0032] Figure 6 This is a schematic diagram showing the microhardness test results of tungsten components; where, Figure 6 Figure (a) in the figure is a schematic diagram of the microhardness test results of tungsten components directly prepared by SLM; Figure 6 Figure (b) shows the microhardness test results of a tungsten component that underwent SLM-like treatment and underwent deformation.

[0033] Figure 7 A sintering quality diagram of tungsten components prepared by the SPS method. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0035] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising" or "including" include not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The terminology used herein is generally that commonly used by those skilled in the art; in case of any discrepancy with commonly used terminology, the terminology used herein shall prevail.

[0036] Furthermore, for ease of description, spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper” may be used herein to describe the relationship between one element or component and another (or other) element or component as shown in the figure. In addition to the orientation shown in the figure, spatial relative terms are intended to include different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein can be interpreted accordingly.

[0037] In this paper, the term "SLM" (Selective Laser Melting) is a method in the field of additive manufacturing technology that can selectively melt powder layer by layer using a laser beam generated by a laser based on a 3D CAD model to produce single or multiple metal parts with complex geometries without the need for molds for specific parts.

[0038] In this paper, the term "discharge plasma sintering" (SPS) refers to a method of preparing a bulk material with a certain density and strength by sintering raw material powder with plasma under high temperature and high pressure.

[0039] In this paper, the term "hot isostatic pressing" (HIP) refers to a densification process in which isotropic pressure is applied to tungsten materials at high temperatures and high gas pressures (such as argon).

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Figure 1 An exemplary method for preparing a high-melting-point metal component according to a first embodiment of the present invention is shown.

[0042] like Figure 1 As shown, the method for preparing this high-melting-point metal component includes the following steps:

[0043] S10: High-melting-point metal component blanks are prepared using the SLM method to obtain high-density high-melting-point metal component blanks. However, if the SPS method is used to prepare high-melting-point metal component blanks, the density will be lower.

[0044] S20: Improved heat treatment is applied to high-melting-point metal component blanks. The improved heat treatment involves heat treatment of the high-melting-point metal component blanks under high temperature, high pressure and long duration. During the improved heat treatment, the high-melting-point metal component blanks undergo plastic deformation to obtain finished high-melting-point metal components. The high temperature is not lower than 1450℃, the high pressure is not lower than 25MPa, and the heat treatment time is not less than 65min.

[0045] In some embodiments, such as Figure 2 As shown, step S20 includes step S21: Before heating the high-melting-point metal component blank, the high-melting-point metal component blank is placed in a sealed container space, and the outer periphery of the high-melting-point metal component blank in the container space is filled with a powder that is chemically inert, thermally conductive, and has low electrical conductivity. This is to prevent the powder from chemically reacting with the high-melting-point metal component while ensuring uniform heat conduction, thereby reducing the thermal stress of the high-melting-point metal component blank during improved heat treatment and preventing cracking; and to ensure that the high-melting-point metal component blank is not affected in the SPS discharge plasma sintering furnace. In some embodiments, in step S21, the chemical inertness of the powder filling the outer periphery of the high-melting-point metal component blank in the container space is achieved by ensuring that it does not chemically react with high-melting-point metals (such as tungsten, molybdenum, nickel-titanium alloys, etc.) below 1500°C, and the thermal conductivity is achieved by ensuring that the thermal conductivity is between 1 and 200 W·m. -1 ·K -1 Low conductivity, with conductivity below 10. -5 S / m. In some embodiments, in step S21, the powder filling the outer periphery of the high-melting-point metal component blank in the accommodating space is made of alumina, silicon carbide, zirconium oxide, and alumina-like ceramic materials to give the powder suitable chemical inertness, thermal conductivity, and low electrical conductivity; preferably, alumina powder is used to reduce manufacturing costs. The weight of the powder with chemical inertness, thermal conductivity, and low electrical conductivity is positively correlated with the volume of the high-melting-point metal component blank. Taking alumina powder as an example, when the high-melting-point metal component blank is 180 mm², the weight of the powder is positively correlated with the volume of the high-melting-point metal component blank. 3 At that time, the amount of alumina powder is 5~10g. In some embodiments, in step S21, the particle size range of the powder filling the outer periphery of the high melting point metal component blank in the accommodating space is 1μm~100μm, so as to ensure more uniform heating and faster temperature rise, while achieving convenient demolding and avoiding the problem of difficult demolding due to fine particle size.

[0046] In some embodiments, continue to refer to Figure 2As shown, step S20 also includes step S22 after step S21: controlling the pressure of the accommodating space containing the high-melting-point metal component blank and the powder with chemical inertness, thermal conductivity and low electrical conductivity to above 25 MPa, so that the powder with chemical inertness, thermal conductivity and low electrical conductivity and the high-melting-point metal component blank to be heated are in full contact, so that the heat conduction is more uniform, which is conducive to the uniform heating of the high-melting-point metal component blank in the subsequent process; in addition, pre-pressurizing before heating can avoid the need for rapid pressurization during the heating process, reducing the risk of stress concentration and crack propagation caused by thermal gradient.

[0047] In some embodiments, the container material is graphite. Since graphite has a melting point of 3850±50℃, using high-melting-point graphite as a container for high-melting-point metal components ensures the container's stability during heat treatment. Furthermore, graphite's excellent electrical and thermal conductivity and high-temperature stability ensure temperature uniformity of the high-melting-point metal component blanks during heat treatment and prevent adhesion between the blanks and the heat treatment process. Simultaneously, graphite's low cost and high machinability significantly reduce manufacturing costs.

[0048] In some embodiments, such as Figure 3 As shown, the container includes a female mold and a punch that are compatible with each other. The female mold has a cavity that is compatible with the punch. The punch and the female mold together form an accommodating space. The pressure is an axial pressure along the axis of the female mold. The pressure in the accommodating space can be adjusted by the depth of the punch inserted into the cavity of the female mold. The adjustment method is relatively convenient.

[0049] In some embodiments, continue to refer to Figure 2 As shown, step S20 also includes step S23 after step S22: first, the furnace cavity of the heat treatment furnace undergoing the improved heat treatment is evacuated, and then argon gas is introduced to control the vacuum degree at 1.0~2.0×10⁻⁶. 3 mbar. This prevents oxidation of high-melting-point metal component blanks during the improved heat treatment process.

[0050] In some embodiments, in step S23, the vacuum level of the furnace cavity needs to reach 1~9.9×10⁻⁶ before argon gas is introduced. -2 mbar is used to ensure that impurities in the furnace cavity are removed as much as possible to guarantee the treatment effect.

[0051] In some embodiments, in step S23, the argon gas introduction rate is 2~10 L / min to avoid insufficient atmosphere replacement in the furnace cavity due to excessive or insufficient flow rate.

[0052] In some embodiments, in step S24, the pressure increase rate of the container's accommodating space is 0.5~2 MPa·min.-1 This is to avoid the formation of new cracks in high-melting-point metal component blanks due to excessively rapid pressure increase.

[0053] In some embodiments, continue to refer to Figure 2 As shown, step S20 also includes step S24 after step S23: the heating rate of the furnace cavity of the heat treatment furnace is controlled at 100±10℃ / min, and / or the pressure of the container space is increased to ensure that the high melting point metal component blank undergoes plastic deformation during the heat treatment; moreover, the heating rate of 100±10℃ / min can enable the high melting point metal component blank to quickly reach the target temperature range, which is beneficial to reduce the risk of grain growth and avoid the risk of oxidation caused by long-term high temperature.

[0054] In some embodiments, the high temperature for improving heat treatment is 1450~1500°C.

[0055] In some embodiments, the heat treatment time is improved to 65 min to 90 min.

[0056] In some embodiments, the high pressure for improving heat treatment is 35 MPa to 40 MPa.

[0057] In this embodiment, the process in step S20 is similar to that of the SPS method, both involving improved heat treatment in an SPS discharge plasma sintering furnace. The main differences are higher temperature and pressure, and a longer processing time. Furthermore, the inventors have found that this method is primarily suitable for preparing small-volume high-melting-point metal components. When the component volume is too large, improvements in crack and grain size can only occur on the surface of the component. Therefore, in some embodiments, the volume V of the high-melting-point metal component blank is controlled to be less than 180 mm². 3 This ensures that the cracks inside the high-melting-point metal component are healed and that the internal grains are refined.

[0058] The applicant discovered through research that in step S10, the SLM method is required to prepare high-melting-point metal component blanks, and other methods (such as the SPS method) cannot be used. This is because the SLM method can produce microstructures with high dislocation density and specific morphology under rapid melting and solidification conditions (such as...). Figure 4 As shown in Figure (a), it can achieve near-net-shape forming of complex components, so that after high-temperature, high-pressure, long-term improvement heat treatment, the crystal structure of the high-melting-point metal component blank prepared by SLM method can be further refined, and the cracks generated in the high-melting-point metal component blank during the SLM preparation process can be healed during the improvement heat treatment, reducing internal defects of the component. However, if the high-melting-point metal component blank is prepared by SPS method, the density of the prepared high-melting-point metal component blank will be poor (e.g., Figure 7As shown in the figure, it is impossible to achieve crack healing and grain refinement through subsequent improved heat treatment.

[0059] When the high temperature of the improved heat treatment is 1450~1500℃, the improved heat treatment time is 65min~90min, and the improved heat treatment pressure is 35MPa~40MPa, during the improved heat treatment, when the high melting point metal component blank undergoes plastic deformation, the high temperature and high pressure process used in the improved heat treatment promotes the healing of cracks in the high melting point metal component blank prepared by the SLM method (e.g., Figure 4 Figure (c) in the middle and Figure 5 (As shown in Figure (b)). Simultaneously, due to the use of high temperature and long processing time in the improved heat treatment process, the high-melting-point metal component blanks prepared by the SLM method undergo plastic deformation. This not only effectively inhibits the elongation of grains under prolonged high temperature but also causes grain breakage in the high-melting-point metal component blanks, achieving a grain refinement effect. Generally, during the improved heat treatment, the amount of plastic deformation in the high-melting-point metal component blanks is controlled between 0.5% and 10% to ensure that the high-melting-point metal component blanks exhibit grain refinement after high-temperature and high-pressure improved heat treatment. The high-melting-point metal component preparation method of this embodiment can significantly refine the grains of high-melting-point metal component blanks prepared by the SLM method, improving their density and mechanical properties; at the same time, it can improve the grain morphology of high-melting-point metal component blanks and reduce the anisotropy of high-melting-point metal component blanks prepared by the SLM method.

[0060] The high-melting-point metal component preparation method of this embodiment is not only applicable to the optimization of tungsten components, but also has the potential to be extended to other high-melting-point, difficult-to-machine metals such as tungsten alloys and molybdenum, as well as metal materials prone to cracking during SLM forming, such as NiTi alloys. The metallographic image of the tungsten component prepared using the high-melting-point metal component preparation method of this embodiment is shown below. Figure 4 As shown in Figure (c), with Figure 4 Compared to the metallographic image of the tungsten component directly prepared by SLM shown in Figure (a), the tungsten component prepared by the high-melting-point metal component preparation method of this embodiment has a significantly smaller grain size, and the grain morphology transforms into equiaxed, uniform small grains, providing a microscopic basis for improving the performance of the tungsten component. The grain size of the tungsten component prepared by the high-melting-point metal component preparation method of this embodiment is significantly reduced. Figure 5 The average grain size of the tungsten component prepared by the high-melting-point metal component preparation method of this embodiment is shown more clearly in the figure. Figure 5 As shown in Figure (b), it is 13.3 μm, and... Figure 5Compared to the average grain size of 36.5 μm of the tungsten component directly prepared by SLM shown in Figure (a), the grain size of the tungsten component prepared by the high melting point metal component preparation method of this embodiment is greatly reduced, equivalent to 0.36 times the average grain size of the tungsten component directly prepared by SLM.

[0061] In some embodiments, the improved cooling method for heat treatment is natural cooling. Natural cooling can employ air cooling or furnace cooling (i.e., during the cooling process, the high-melting-point metal component blank is naturally cooled to room temperature within the vacuum chamber of, for example, an SPS (Spark Plasma Sintering) furnace. Since the SPS furnace has its own circulating water system to maintain its wall temperature, the cooling rate is greater than that of conventional furnace cooling), to prevent grain growth in the high-melting-point metal component blank during cooling. Furthermore, natural aging can reduce the stress in the finished high-melting-point metal component, improving its mechanical properties. The microhardness of the tungsten component prepared by the high-melting-point metal component preparation method of this embodiment is effectively improved. The average microhardness of the tungsten component prepared by the high-melting-point metal component preparation method of this embodiment is as follows: Figure 6 As shown in Figure (b), the value is 467.3 Hv, compared to... Figure 6 Compared to the tungsten component prepared directly by SLM as shown in Figure (a), which has an average microhardness of 401.1 Hv, the tungsten component prepared by the high melting point metal component preparation method of this embodiment has a significantly improved average microhardness.

[0062] The difference between the existing high-melting-point metal component preparation method (such as the preparation method mentioned in the background patent) and the high-melting-point metal component preparation method of the first embodiment lies in that step S20 uses the SPS method. The heat treatment temperature range of the SPS method is 1100℃~1400℃, the loading pressure range is 30MPa~40MPa, and the holding time is 15min~60min, while avoiding deformation of the high-melting-point metal component blank. Since the SPS method does not cause deformation of the high-melting-point metal component blank, it can only achieve the effect of healing internal cracks in the high-melting-point metal component blank through high temperature and high pressure (e.g., Figure 4 (As shown in Figure (b)); it cannot achieve the effect of refining grains, and there is even a tendency for grain growth during high-temperature processes; such as Figure 4 As shown in Figure (b), the tungsten components prepared using existing techniques have large grain sizes and exhibit grain twisting and elongation.

[0063] Example 1

[0064] The first step involves using SLM to fabricate a high-density tungsten shaped part with a volume of 180 mm². 3 .

[0065] The second step is to place the SLM tungsten forming part into a cylindrical graphite mold in an SPS discharge plasma sintering furnace, and fill the mold cavity with 10g of alumina powder, so that the alumina powder fully covers all directions of the component.

[0066] The third step is to preload a pressure of approximately 25 MPa into the graphite mold.

[0067] The fourth step is to first evacuate the furnace cavity, then slowly introduce argon gas until the vacuum level reaches 2.0 × 10⁻⁶. 3 .

[0068] Fifth step: Under argon protection, the system is rapidly heated to 1500℃ at a rate of approximately 100℃ / min, while the axial pressure is gradually increased from the preload value to 40MPa; the temperature and pressure are maintained for 90 minutes.

[0069] Step 6: Allow to cool naturally to room temperature.

[0070] The metallographic image of the tungsten component prepared in this embodiment is as follows. Figure 4 As shown in Figure (c), the EBSD analysis graph is as follows: Figure 5 As shown in Figure (b), the schematic diagram of the microhardness test results is as follows. Figure 6 As shown in Figure (b).

[0071] Example 2

[0072] The first step involves using SLM to fabricate a high-density tungsten shaped part with a volume of 160 mm². 3 .

[0073] The second step is to place the SLM tungsten forming part into a cylindrical graphite mold in an SPS discharge plasma sintering furnace, and fill the mold cavity with 5g of alumina powder, so that the alumina powder fully covers all directions of the component.

[0074] The third step is to preload a pressure of approximately 25 MPa into the graphite mold.

[0075] The fourth step is to first evacuate the furnace cavity, then slowly introduce argon gas until the vacuum level reaches 1.0 × 10⁻⁶. 3 .

[0076] Fifth, under argon protection, the system is rapidly heated to 1450℃ at a rate of approximately 100℃ / min, while the axial pressure is gradually increased from the preload value to 35MPa; the temperature and pressure are maintained for 65 minutes.

[0077] Step 6: Allow to cool naturally to room temperature.

[0078] Example 3

[0079] The first step involves using SLM to fabricate a high-density tungsten shaped part with a volume of 165 mm². 3 .

[0080] The second step is to place the SLM tungsten forming part into a cylindrical graphite mold in an SPS discharge plasma sintering furnace, and fill the mold cavity with 7g of alumina powder, so that the alumina powder fully covers all directions of the component.

[0081] The third step is to preload a pressure of approximately 25 MPa into the graphite mold.

[0082] The fourth step is to first evacuate the furnace cavity, then slowly introduce argon gas until the vacuum level reaches 1.5 × 10⁻⁶. 3 .

[0083] Fifth step: Under argon protection, the system is rapidly heated to 1470℃ at a rate of approximately 100℃ / min, while the axial pressure is gradually increased from the preload value to 37MPa; the temperature and pressure are maintained for 75 minutes.

[0084] Step 6: Allow to cool naturally to room temperature.

[0085] Example 4

[0086] The first step involves using SLM to fabricate a high-density tungsten shaped part with a volume of 170 mm². 3 .

[0087] The second step is to place the SLM tungsten forming part into a cylindrical graphite mold in an SPS discharge plasma sintering furnace, and fill the mold cavity with 5g of alumina powder, so that the alumina powder fully covers all directions of the component.

[0088] The third step is to preload a pressure of approximately 25 MPa into the graphite mold.

[0089] The fourth step is to first evacuate the furnace cavity, then slowly introduce argon gas until the vacuum level reaches 1.0 × 10⁻⁶. 3 .

[0090] Fifth step: Under argon protection, the system is rapidly heated to 1500℃ at a rate of approximately 100℃ / min, while the axial pressure is gradually increased from the preload value to 40MPa; the temperature and pressure are maintained for 80 minutes.

[0091] Step 6: Allow to cool naturally to room temperature.

[0092] Comparative Example 1

[0093] The first step involves using SLM to fabricate a high-density tungsten shaped part with a volume of 180 mm². 3 .

[0094] The second step is to place the SLM tungsten forming part into a cylindrical graphite mold in an SPS discharge plasma sintering furnace, and fill the mold cavity with 10g of alumina powder, so that the alumina powder fully covers all directions of the component.

[0095] The third step is to preload a pressure of approximately 25 MPa into the graphite mold.

[0096] The fourth step is to first evacuate the furnace cavity, then slowly introduce argon gas until the vacuum level reaches 2.0 × 10⁻⁶. 3 .

[0097] Fifth step: Under argon protection, the system is rapidly heated to 1400℃ at a rate of approximately 100℃ / min; at the same time, the axial pressure is gradually increased from the preload value to 40MPa; the temperature and pressure are maintained for 60 minutes.

[0098] Step 6: Allow to cool naturally to room temperature.

[0099] The metallographic image of the tungsten component prepared in this embodiment is as follows. Figure 4 As shown in Figure (b).

[0100] Comparative Example 2

[0101] A high-density tungsten formed part with a volume of 180 mm² was prepared using SLM. 3 .

[0102] The metallographic image of the tungsten component prepared in this embodiment is as follows. Figure 4 As shown in Figure (a), the EBSD analysis diagram is as follows: Figure 5 As shown in Figure (a), the schematic diagram of the microhardness test results is as follows. Figure 6 As shown in Figure (a).

[0103] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing high-melting-point metal components, characterized in that, Includes the following steps: S10: High-melting-point metal component blanks are prepared using the SLM method; S20: Improve the heat treatment of the high melting point metal component blank. The improvement heat treatment is to heat the high melting point metal component blank in a high temperature, high pressure and long time manner. During the improvement heat treatment, the high melting point metal component blank undergoes plastic deformation to obtain the finished high melting point metal component. The high-melting-point metal component is a tungsten component; In step S20, the amount of plastic deformation that causes the high-melting-point metal component blank to undergo plastic deformation during the improved heat treatment is 0.5% to 10%, the high temperature is 1450 to 1500°C, the heat treatment time is 65 min to 90 min, and the high pressure is 35 MPa to 40 MPa.

2. The method for preparing high-melting-point metal components according to claim 1, characterized in that, Step S20 includes step S21: before heating the high melting point metal component blank, the high melting point metal component blank is placed in the sealed containment space of the container, and the outer periphery of the high melting point metal component blank in the containment space is filled with powder that has chemical inertness, thermal conductivity and low electrical conductivity.

3. The method for preparing high-melting-point metal components according to claim 2, characterized in that, In step S21, the powder filling the outer periphery of the high-melting-point metal component blank in the accommodating space is chemically inert to the point that it does not chemically react with the high-melting-point metal below 1500°C, and its thermal conductivity is achieved to be between 1 and 200 W·m. -1 ·K -1 Low conductivity, with conductivity below 10. -5 S / m.

4. The method for preparing high-melting-point metal components according to claim 2, characterized in that, The improved heat treatment cooling method is natural cooling; and / or The container is made of graphite.

5. The method for preparing high-melting-point metal components according to claim 2, characterized in that, In step S21, the powder filling the outer periphery of the high-melting-point metal component blank in the accommodating space is made of alumina, silicon carbide, zirconium oxide, and alumina-like ceramic materials; and / or In step S21, the particle size range of the powder filling the outer periphery of the high melting point metal component blank in the accommodating space is 1μm~100μm.

6. The method for preparing high-melting-point metal components according to claim 2, characterized in that, Step S20 further includes step S22 after step S21: controlling the pressure of the accommodating space containing the high-melting-point metal component blank and the powder having chemical inertness, thermal conductivity, and low electrical conductivity to above 25 MPa; and / or The container includes a female mold and a punch that are adapted to each other. The female mold has a cavity that is adapted to the punch. The punch and the female mold together form the receiving space. The pressure is an axial pressure along the axis of the female mold.

7. The method for preparing high-melting-point metal components according to claim 6, characterized in that, Step S20 further includes step S23 after step S22: first, the furnace cavity of the heat treatment furnace undergoing the improved heat treatment is evacuated, and then argon gas is introduced to control the vacuum level at 1.0~2.0×10⁻⁶. 3 mbar.

8. The method for preparing high-melting-point metal components according to claim 7, characterized in that, Step S20 further includes step S24 after step S23: controlling the heating rate of the furnace cavity of the heat treatment furnace at 100±10℃ / min, and / or increasing the pressure of the container's containment space; and / or In step S23, the vacuum level of the furnace cavity needs to reach 1~9.9×10 before argon gas is introduced. -2 mbar.

9. The method for preparing high-melting-point metal components according to claim 8, characterized in that, In step S23, the argon gas introduction rate is 2~10 L / min; and / or In step S24, the pressure increase rate of the lifting container's containment space is 0.5~2 MPa·min. -1 .

10. The method for preparing a high-melting-point metal component according to any one of claims 2 to 9, characterized in that, The volume V of the high-melting-point metal component blank is less than 180 mm². 3 .

Images