High-temperature-resistant high-strength tungsten alloy part, preparation method and application

Abstract

The invention provides a high-temperature-resistant high-strength tungsten alloy part, a preparation method and application. Relates to the field of metal materials. The invention provides a preparation method of a high-temperature-resistant high-strength tungsten alloy part, which comprises the following steps: mixing 88-94% of tungsten, 3-7% of nickel, 2-3% of iron, 0.2-1% of rhenium and 0.2-1% of cobalt metal powder, carrying out cold isostatic pressing treatment, shaping, sintering, carrying out hot isostatic pressing treatment, and machining to obtain a target alloy part, the tensile strength of the tungsten alloy part at 1300 DEG C reaches up to 242 MPa, the normal-temperature ductility is 20%, and the tensile strength of the tungsten alloy part at 1300 DEG C reaches up to 242 MPa. The alloy part can adapt to a high-temperature environment in a monocrystalline silicon crystal growth furnace, when the alloy part is used for a heavy hammer part for hanging crystals, the tensile strength and the elongation of the alloy part can meet production requirements, and the service life of the alloy part exceeds two years.

Description

Technical Field

[0001] The present invention relates to the field of metal materials, and in particular to a high-temperature resistant and high-strength tungsten alloy part, a preparation method and application thereof Background Art In a single crystal silicon growth furnace, the weight component plays a vital role. It is hung at the lower end of the suspension rope and is responsible for stabilizing the straightening of the crystal rod during the pulling process. Since the lower end of the weight works in a high temperature area of ​​1300℃ for a long time, it is difficult for low melting point materials to meet the working conditions. At present, molybdenum-based alloy material is the main material used for the weight, and its tensile strength at room temperature can reach 300Mpa, and its tensile strength at 1300℃ is 50Mpa. Through reasonable design, it can basically meet the strength requirements of crystal rod pulling to a certain extent.

[0002] However, with the development of single crystal silicon production technology, the weight and size of the crystal rods are increasing. Under this trend, the limitations of molybdenum-based alloy materials as weight materials are gradually becoming more prominent. Its safety factor continues to decrease with the increase of crystal rod specifications, resulting in a gradual increase in the risk and frequency of breakage. This will not only affect the production efficiency of single crystal silicon, but may also cause production accidents due to the breakage of the weight, causing damage to equipment and increasing production costs.

[0003] Therefore, monocrystalline silicon manufacturers urgently need to find an alloy material that can maintain high strength and is not easy to break in a high temperature environment of 1300°C to replace the existing molybdenum-based alloy materials, so as to better adapt to the production needs of increased crystal rod weight and size, and ensure the stability, efficiency and safety of the monocrystalline silicon production process. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the present invention aims to provide a high-temperature resistant and high-strength tungsten alloy part, a preparation method and an application thereof.

[0005] One of the purposes of the present invention is to provide a method for preparing a high-temperature resistant and high-strength tungsten alloy part, wherein the formula of the tungsten alloy part is calculated by mass percentage, with a total mass of 100%, including 88-94% tungsten, 3-7% nickel, 2-3% iron, 0.2-1% rhenium, 0.2-1% cobalt, and the rest being unavoidable impurities; Wherein, the mass ratio of rhenium to cobalt is 1:1.

[0006] Preferably, the preparation method comprises the following steps: Firstly, metal powders selected according to the formula of the tungsten alloy part are mixed to obtain mixed powder, and the mixed powder is subjected to cold isostatic pressing to obtain a compact; Shaping the compact to obtain a shaped compact; Sintering the shaped blank to obtain a sintered blank; The sintered blank is subjected to hot isostatic pressing and then machined to obtain a target alloy part; Preferably, the average particle size of the metal powder is 2.0-4.0 μm, and the purity is above 99.95%; the mixing time is 20-40 hours.

[0007] Preferably, the pressure of the cold isostatic pressing treatment is 190-240 MPa, and the holding time is 10-30 min.

[0008] Preferably, the sintering step is carried out in a mixed atmosphere of argon and hydrogen, and the ratio of argon to hydrogen is 3-4:1.

[0009] Preferably, the sintering comprises the following steps: first heating to 180-250°C, keeping at 180-250°C for 1-4 hours, then heating to 1200-1300°C, keeping at 1200-1300°C for 1-4 hours, then heating to 1400-1500°C for sintering, and the sintering time is 1-3 hours.

[0010] Preferably, the heating rate is 50-100° C. / h.

[0011] Preferably, the relative density of the sintered compact is above 99%.

[0012] Preferably, the hot isostatic pressing treatment pressure is 120-180 MPa, the temperature is 1200-1400° C., and the holding time is 3-5 h.

[0013] A second object of the present invention is to provide a high-temperature resistant and high-strength tungsten alloy part produced by the preparation method as described above.

[0014] The third object of the present invention is to provide a high temperature resistant and high strength tungsten alloy part as described above.

[0015] Beneficial effects of the present invention: The invention provides a method for preparing a high-temperature resistant and high-strength tungsten alloy part. The method comprises the following steps: firstly mixing metal powders of 88-94% tungsten, 3-7% nickel, 2-3% iron, 0.2-1% rhenium and 0.2-1% cobalt, performing cold isostatic pressing, performing shaping and sintering, and then performing hot isostatic pressing and machining to obtain a target alloy part. The tungsten alloy part has a room temperature tensile strength of up to 1520 MPa, a tensile strength of up to 542 MPa at 1300°C, and an elongation of 14%. The alloy part can adapt to the high temperature environment in a single crystal silicon crystal growth furnace. When used for a heavy hammer component for hanging crystals, the tensile strength and elongation of the alloy part can meet production requirements, and the service life exceeds two years, meeting the service life requirements. DETAILED DESCRIPTION

[0016] According to the first aspect of the invention, a method for preparing a high-temperature resistant and high-strength tungsten alloy part is provided, characterized in that the formula of the tungsten alloy part is calculated by mass percentage, with a total mass of 100%, including 88-94% tungsten, 3-7% nickel, 2-3% iron, 0.2-1% rhenium, 0.2-1% cobalt, and the rest are unavoidable impurities; Wherein, the mass ratio of rhenium to cobalt is 1:1.

[0017] In the present invention, tungsten is the main component of the alloy, accounting for 88-94%. It has a very high melting point (3410°C), which enables the alloy to remain solid in a high temperature environment and provides basic structural strength. At 1300°C, the crystal structure of tungsten can still maintain a high stability, and its high strength characteristics contribute to the overall strength of the alloy, and it can withstand large external forces without being easily deformed. The nickel content is 3-7%, and the iron content is 2-3%, and they mainly act as bonding phases. Nickel and iron can form a good bond between tungsten particles and fill the gaps between tungsten particles. At high temperatures, the atomic diffusion capacity of nickel and iron is enhanced, which can better wet the tungsten particles and make the structure of the alloy more compact. This bonding effect enhances the overall strength of the alloy, and helps to transfer and disperse stress, preventing fracture caused by local stress concentration. When subjected to external force, the stress can be evenly distributed on the tungsten particles through the bonding phases of nickel and iron, avoiding the destruction of individual tungsten particles due to excessive stress. Rhenium is a metal with a high melting point (3180°C) and good ductility. It can play a role in solid solution strengthening in alloys. At high temperatures, rhenium atoms dissolve into the tungsten lattice, causing lattice distortion and hindering dislocation movement, thereby improving the strength of the alloy. At the same time, cobalt also has a similar strengthening effect, and it and rhenium can also improve the toughness of the alloy. Cobalt can refine the grain structure of the alloy and reduce the brittleness caused by coarse grains. When rhenium and cobalt exist in a mass ratio of 1:1, their strengthening effects can synergize with each other. The lattice distortion caused by rhenium can provide more nucleation sites for cobalt-refined grains. At the same time, the grain boundaries after cobalt refinement can further hinder dislocation movement and enhance the solid solution strengthening effect of rhenium. This synergistic effect enables the alloy to maintain high strength at high temperatures (such as 1300°C) and more effectively resist deformation and damage when subjected to external forces. Without this balance, increasing the rhenium content alone may result in an increase in alloy strength but an excessive decrease in toughness, resulting in embrittlement; while increasing the cobalt content alone may increase toughness, but the improvement in strength may not achieve the expected effect. The 1:1 mass ratio can optimize the overall performance of the alloy so that it has a good match between strength and toughness in a high temperature environment. In a high temperature environment, the alloy will undergo repeated thermal cycles and is prone to thermal fatigue. When rhenium and cobalt are present in a 1:1 mass ratio, they can improve the thermal fatigue performance of the alloy. This is because they work together to optimize the microstructure of the alloy. During thermal cycling, rhenium and cobalt can stabilize the grain boundary structure of the alloy and reduce the migration and sliding of grain boundaries under thermal stress. At the same time, the strengthening effect and toughness improvement effect they produce also help the alloy better resist the crack initiation and propagation caused by thermal stress during thermal cycling, thereby extending the service life of the alloy in a high temperature environment.

[0018] In a preferred embodiment of the present invention, the preparation method comprises the following steps: Firstly, metal powders selected according to the formula of the tungsten alloy part are mixed to obtain mixed powder, and the mixed powder is subjected to cold isostatic pressing to obtain a compact; Shaping the compact to obtain a shaped compact; Sintering the shaped blank to obtain a sintered blank; The sintered blank is subjected to hot isostatic pressing and then machined to obtain a target alloy part.

[0019] In the present invention, cold isostatic pressing can bring metal particles into close contact and generate mechanical bonding forces, including friction and meshing forces. The bonding strength between particles is further enhanced. When subjected to external force, this mechanical interlocking structure can effectively resist the external force, prevent loosening and separation between particles, thereby improving the strength of the pressed green sheet. The metal powder is compacted in all directions, internal defects are reduced, and stress concentration points are correspondingly reduced. The overall strength of the material is improved after sintering and post-treatment. Shaping further optimizes the shape and dimensional accuracy of the green sheet, so that the alloy is more evenly heated and stressed during subsequent sintering and hot isostatic pressing, avoiding defects caused by local overheating or uneven stress. Hot isostatic pressing after sintering can further eliminate residual pores in the sintered green sheet, making the alloy more dense, and significantly improving the strength and toughness of the material. Due to the synergistic effect of high temperature and high pressure, the internal structure of the alloy is more uniform, stress is effectively released, and thermal fatigue performance is improved.

[0020] In a preferred embodiment of the present invention, the average particle size of the metal powder is 2.0-4.0 μm, and the purity is above 99.95%; and the mixing time is 20-40 hours.

[0021] In the present invention, when the average particle size of the metal powder is 2.0-4.0 μm, during the solidification process of the alloy, the fine powder particles can be uniformly distributed in the matrix as a dispersed phase. These fine particles can effectively hinder the movement of dislocations. Dislocations are a type of linear defect in a crystal, and the plastic deformation of the material is mainly achieved through the movement of dislocations. When dislocations encounter these fine dispersed phase particles during movement, they will be pinned by the particles, thereby increasing the yield strength of the material. In tungsten-based alloys, fine second phase particles can significantly improve the strength of the alloy, just as adding fine sand and gravel to concrete can enhance its strength. Smaller powder particle sizes are conducive to obtaining finer grain structures during sintering and other molding processes. According to the Hall-Petch relationship, the yield strength of the material is inversely proportional to the square root of the grain size. That is, the smaller the grain, the higher the strength of the material. When the metal powder particle size is within this range, the growth of the grains can be effectively restricted during the preparation process, thereby improving the strength of the alloy and reducing the tendency to fracture due to coarse grains.

[0022] Purity above 99.95% means that the impurity content in the alloy is very low. Impurity atoms may cause lattice distortion in the alloy, which can lead to local stress concentration. When the alloy is subjected to external forces, these stress concentration points are likely to become the origin of cracks, thereby increasing the risk of fracture. High-purity metal powder can reduce this stress concentration caused by impurities, making the internal structure of the alloy more uniform, thereby improving the strength and toughness of the alloy and reducing the fracture rate. Some impurity elements may form a low melting point phase with tungsten, which is prone to thermal cracking in a high temperature environment, and high-purity powder can avoid this.

[0023] Mixing time of 20-40h can make the various components in the alloy mix more evenly. In tungsten alloys, other alloying elements (such as nickel, iron, cobalt, etc.) may be added to improve their properties. Sufficiently long mixing time can ensure that these elements are evenly distributed in the tungsten matrix, avoiding local performance differences caused by component segregation. When the alloy is subjected to external force, the uniform composition can make the stress evenly distributed, preventing local stress from being too large and causing fracture. If some reinforcement phases are not fully mixed, stress concentration may occur around these agglomerated reinforcement phases when the alloy is under load, causing premature fracture of the material. Longer mixing time helps to form a uniform microstructure, thereby increasing the strength of the alloy and reducing the fracture rate.

[0024] In a preferred embodiment of the present invention, the pressure of the cold isostatic pressing treatment is 190-240 MPa, and the holding time is 10-30 min.

[0025] In a preferred embodiment of the present invention, the sintering step is carried out in a mixed atmosphere of argon and hydrogen, and the ratio of argon to hydrogen is 3-4:1.

[0026] In the present invention, argon is an inert gas, which mainly plays a protective role during the sintering process. Under high temperature environment, tungsten alloy is easy to react with oxygen in the air to form an oxide film. This oxide film may affect the sintering bonding between alloy particles and reduce the density of the alloy. Argon can prevent oxygen from contacting the alloy and avoid the occurrence of oxidation reaction. Hydrogen is a strong reducing agent. Tungsten alloy raw materials may contain a small amount of oxide impurities, such as tungsten oxide (WO3, WO2, etc.). Under high temperature sintering environment, hydrogen can react with these oxides to reduce tungsten oxide to metallic tungsten. It can purify the alloy system and reduce the presence of impurity phases. The microstructure of the alloy is purer, which helps to improve the strength and toughness of the alloy and reduce the fracture rate. The ratio of argon to hydrogen is 3~4:1, which can effectively protect the alloy while ensuring the reduction effect, maintain the stability of the alloy composition, and help to form a uniform and dense microstructure, thereby improving the strength of the alloy and reducing fractures caused by composition changes or oxidation.

[0027] In a preferred embodiment of the present invention, the sintering comprises the following steps: first heating to 180-250°C, keeping at 180-250°C for 1-4 hours, then heating to 1200-1300°C, keeping at 1200-1300°C for 1-4 hours, then heating to 1400-1500°C for sintering, and the sintering time is 1-3 hours.

[0028] In the present invention, the main purpose of heat preservation at 180-250°C is to remove the adsorbed water and some organic impurities in the alloy powder. During the storage and transportation process, the metal powder will absorb a certain amount of water on the surface. If the water is not removed in advance, water vapor may be formed during the subsequent high-temperature sintering process, resulting in defects such as pores inside the alloy. The temperature range of 180-250°C is a more reasonable preheating temperature. Heat preservation at this temperature for 1-4 hours can effectively volatilize water and some low-boiling impurities without causing significant changes in the alloy composition. Considering the stability of the alloy composition, the main components such as tungsten (melting point 3422°C), nickel (melting point 1453°C), iron (melting point 1538°C), rhenium (melting point 3180°C) and cobalt (melting point 1495°C) in the formula can all remain solid at this temperature, and no chemical reaction will occur. The element diffusion phenomenon in the alloy is also very slight, which ensures the relative stability of the alloy composition in the preheating stage and lays a good foundation for the subsequent sintering process. Heating to 1200~1300℃ and keeping it for 1~4h is an important stage to promote alloy densification. In this temperature range, the atoms in the alloy begin to have higher activity and the atomic diffusion rate accelerates. For tungsten alloy, due to the high tungsten content (88-94%), the diffusion of tungsten atoms requires a higher temperature to activate. This temperature range enables tungsten atoms and atoms of other alloying elements (nickel, iron, rhenium and cobalt) to begin to diffuse with each other, gradually filling the pores between powder particles and gradually increasing the density of the alloy.

[0029] Considering the temperature requirements for the interaction of alloying elements, elements such as nickel, iron, rhenium and cobalt can better interact with tungsten at this temperature. Nickel can form a solid solution with tungsten at this temperature to enhance the toughness of the alloy; rhenium can increase the recrystallization temperature of the alloy, which helps to maintain the microstructural stability of the alloy at higher temperatures. A holding time of 1 to 4 hours allows these alloying elements to fully diffuse and react to form a uniform microstructure.

[0030] The purpose of sintering at 1400~1500℃ for 8~10h is to achieve the best performance of the alloy. At this high temperature stage, the various components in the alloy further diffuse and fuse, which can eliminate most of the residual pores and make the density of the alloy close to the theoretical density. For this high tungsten content alloy, the higher temperature can ensure the formation of more stable chemical bonds and microstructures between tungsten atoms and other alloying elements.

[0031] The alloy is used in high temperature environment, and this final sintering temperature can improve the high temperature strength and creep resistance of the alloy. The sintering temperature of 1400~1500℃ helps the alloy maintain good mechanical properties at high temperature and reduce the possibility of fracture.

[0032] In a preferred embodiment of the present invention, the heating rate is 50-100° C. / h.

[0033] In a preferred embodiment of the present invention, the relative density of the sintered compact is above 99%.

[0034] In a preferred embodiment of the present invention, the hot isostatic pressing treatment pressure is 120-180 MPa, the temperature is 1200-1400° C., and the holding time is 3-5 h.

[0035] The holding time of 3~5h can ensure that the effects of pressure and temperature are fully exerted. During this period of time, the alloy is densified under a pressure of 120~180MPa, so that the pores are gradually closed. At the same time, the atoms continue to diffuse at a high temperature of 1200~1400 to achieve the homogenization of the composition and the optimization of the grain boundaries. If the holding time is too short, it may not be possible to completely eliminate the pores and fully homogenize the structure, resulting in the alloy's performance at high temperature not being able to reach the optimal state; if the holding time is too long, it may increase production costs, and the effect of improving the alloy's performance may no longer be obvious.

[0036] According to the second aspect of the present invention, there is provided a high temperature resistant and high strength tungsten alloy part produced by the preparation method as described above.

[0037] The third object of the present invention is to provide an application of the high temperature resistant and high strength tungsten alloy part as described above in a single crystal silicon growth furnace.

[0038] Density test standard GB / T1423-1996, grain size test standard GB / T 6394-2017, room temperature tensile strength test standard GB / T 228-2010, high temperature tensile standard GB / T 228.2-2015.

[0039] Example 1 In this embodiment, a tungsten alloy part with an alloy formula of 89.60% tungsten, 7% nickel, 3% iron, 0.2% rhenium, and 0.2% cobalt is prepared. The preparation method is as follows: Tungsten powder, nickel powder, iron powder, rhenium powder and cobalt powder with a particle size of 2.8 μm were mixed for 24 hours to obtain a mixed powder.

[0040] The mixed powder is placed in a cold isostatic pressing mold for cold isostatic pressing, the cold isostatic pressing pressure is 200 MPa, and the holding time is 10 minutes to obtain a green compact; the green compact is shaped to obtain a shaped green compact; The shaped blank was sintered in a resistance heating furnace; the sintering was carried out in a mixed atmosphere of argon and hydrogen, the ratio of argon and hydrogen was 4:1, and the mixed gas flow rate was 5m 3 / h, heat up at a rate of 80℃ / h, keep warm at 200℃ and 1200℃ for 2h respectively; sintering temperature is 1480℃, keeping warm time is 1h, and sintered blank is obtained.

[0041] The sintered billet is subjected to hot isostatic pressing treatment and then to machining. The hot isostatic pressing treatment pressure is 150 MPa, the temperature is 1300°C, and the holding time is 4 hours to obtain the target alloy parts.

[0042] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 17.1 g / cm 3 The relative density is 99.9% on average. The obtained tungsten alloy material has uniform and fine grains, with an average grain size of 40μm; the tensile strength at room temperature is 1050Mpa, the tensile strength at 1300℃ is 230MPa, the elongation at room temperature is 20%, and the service life is more than 2 years, meeting the life requirements.

[0043] Example 2 In this embodiment, a tungsten alloy part with an alloy formula of 93% tungsten, 3% nickel, 2% iron, 1% rhenium and 1% cobalt is prepared, and the preparation method is the same as that of Example 1.

[0044] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 17.6 g / cm 3 The relative density is 99.9% on average. The obtained tungsten alloy material has uniform and fine grains, with an average grain size of 45μm; the tensile strength at room temperature is 1054Mpa, the tensile strength at 1300℃ is 226MPa, the elongation at room temperature is 23%, and the service life is more than 2 years, meeting the life requirements.

[0045] Example 3 In this embodiment, a tungsten alloy part with an alloy formula of 91.5% tungsten, 5% nickel, 2.5% iron, 0.5% rhenium, and 0.5% cobalt is prepared. The preparation method is the same as that of Example 1.

[0046] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 17.18 g / cm 3 The relative density is 99.9% on average. The obtained tungsten alloy material has uniform and fine grains, with an average grain size of 38μm; the tensile strength at room temperature is 1053Mpa, the tensile strength at 1300℃ is 235MPa, the elongation at room temperature is 25%, and the service life is more than 2 years, meeting the life requirements.

[0047] Example 4 In this embodiment, a tungsten alloy part with an alloy formula of 91.5% tungsten, 5% nickel, 2.5% iron, 0.5% rhenium, and 0.5% cobalt is prepared. The preparation method is as follows: Tungsten powder, nickel powder, iron powder, rhenium powder and cobalt powder with a particle size of 2.8 μm were mixed for 24 hours to obtain a mixed powder.

[0048] The mixed powder is placed in a cold isostatic pressing mold for cold isostatic pressing, the cold isostatic pressing pressure is 200 MPa, and the holding time is 10 minutes to obtain a green compact; the green compact is shaped to obtain a shaped green compact; The shaped blank was sintered in a resistance heating furnace; the sintering was carried out in a mixed atmosphere of argon and hydrogen, the ratio of argon and hydrogen was 3:1, and the mixed gas flow rate was 5m 3 / h, heat up at a rate of 80℃ / h, keep warm at 200℃ and 1200℃ for 2h respectively; sintering temperature is 1462℃, keeping warm time is 1h, and sintered blank is obtained.

[0049] The sintered billet is subjected to hot isostatic pressing treatment and then to machining. The hot isostatic pressing treatment pressure is 150 MPa, the temperature is 1300°C, and the holding time is 4 hours to obtain the target alloy parts.

[0050] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 17.18 g / cm 3 The relative density is 99.9% on average. The obtained tungsten alloy material has uniform and fine grains, with an average grain size of 41μm; the tensile strength at room temperature is 990Mpa, the tensile strength at 1300℃ is 242MPa, the elongation is 25%, and the service life is more than 2 years, meeting the life requirements.

[0051] Example 5 In this embodiment, a tungsten alloy part with an alloy formula of 91.5% tungsten, 5% nickel, 2.5% iron, 0.5% rhenium, and 0.5% cobalt is prepared. The preparation method is as follows: Tungsten powder, nickel powder, iron powder, rhenium powder and cobalt powder with a particle size of 2.8 μm were mixed for 24 hours to obtain a mixed powder.

[0052] The mixed powder is placed in a cold isostatic pressing mold for cold isostatic pressing, the cold isostatic pressing pressure is 200 MPa, and the holding time is 10 minutes to obtain a green compact; the green compact is shaped to obtain a shaped green compact; The shaped blank was sintered in a resistance heating furnace; the sintering was carried out in a mixed atmosphere of argon and hydrogen, the ratio of argon and hydrogen was 3:1, and the mixed gas flow rate was 5m 3 / h, heating at a rate of 80℃ / h, keeping at 200℃ and 1300℃ for 2h respectively; sintering temperature is 1500℃, keeping time is 1h, and sintered blank is obtained.

[0053] The sintered billet is subjected to hot isostatic pressing treatment and then to machining. The hot isostatic pressing treatment pressure is 150 MPa, the temperature is 1300°C, and the holding time is 4 hours to obtain the target alloy parts.

[0054] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 17.12 g / cm 3 The relative density is 99.9% on average. The tungsten alloy material has uniform and fine grains, with an average grain size of 41μm; the tensile strength at room temperature is 1020Mpa, the tensile strength at 1300℃ is 225MPa, the elongation is 27%, and the service life is more than 2 years, meeting the life requirements.

[0055] Comparative Example 1 In this embodiment, a tungsten alloy part with an alloy formula of 95% tungsten, 3% nickel and 2% iron is prepared, and the preparation method is the same as that of Example 1.

[0056] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 18.07 g / cm 3 The relative density is 99.9% on average. The obtained tungsten alloy material has uniform and fine grains, with an average grain size of 48μm; the tensile strength at room temperature is 960Mpa, the tensile strength at 1300℃ is 165MPa, the elongation at room temperature is 18%, and the service life is more than 2 years, meeting the life requirements.

[0057] Comparative Example 2 The formula of the tungsten alloy part prepared in this embodiment is the same as that in embodiment 1, and the preparation method is as follows: Tungsten powder, nickel powder, iron powder, rhenium powder and cobalt powder with a particle size of 2.8 μm were mixed for 24 hours to obtain a mixed powder.

[0058] The mixed powder is placed in a cold isostatic pressing mold for cold isostatic pressing, the cold isostatic pressing pressure is 200 MPa, and the holding time is 10 minutes to obtain a green compact; the green compact is shaped to obtain a shaped green compact; The shaped blank was sintered in a resistance heating furnace; the sintering was carried out in a mixed atmosphere of argon and hydrogen, the ratio of argon and hydrogen was 4:1, and the mixed gas flow rate was 5m 3 / h, heating at a rate of 80℃ / h, keeping at 200℃ and 1200℃ for 2h respectively; sintering temperature is 1480℃, keeping time is 1h, and sintered blank is obtained; The sintered blank is machined to obtain the target alloy part.

[0059] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 17.0 g / cm 3 The relative density is 99% on average. The obtained tungsten alloy material has uniform and fine grains, with an average grain size of 45μm; the tensile strength at room temperature is 880Mpa, the tensile strength at 1300℃ is 182MPa, the elongation is 7%, and the service life is more than 1 year, meeting the life requirements.

[0060] Comparative Example 3 This embodiment is sintered in a hydrogen environment with a gas flow rate of 5m 3 / h, and the remaining steps and parameters are the same as those in Example 1.

[0061] The high-temperature resistant and high-strength tungsten alloy parts prepared in this embodiment are measured by hydrostatic weighing method, and the average actual density is 17.05 g / cm 3 The relative density is 99.5% on average. The obtained tungsten alloy material has uniform and fine grains, with an average grain size of 41μm; the tensile strength at room temperature is 860Mpa, the tensile strength at 1300℃ is 179MPa, the elongation is 6%, and the service life is more than 1 year, meeting the life requirements.

[0062] Comparative Example 4 In this embodiment, a pure molybdenum alloy is prepared, and the preparation method is the same as that of embodiment 1.

[0063] The pure molybdenum alloy obtained in this embodiment has an average actual density of 10.18 g / cm3 and an average relative density of 99.3% measured by hydrostatic weighing method. The longitudinal section of the obtained weight material is a fibrous structure grain, and the cross-sectional grain size is 3 μm; the room temperature tensile strength is 600 MPa, the tensile strength at 1300°C is 50 MPa, the elongation is 3%, and the average service life is 1 year, which is lower than that of tungsten alloy.

Claims

1. A method for preparing a high temperature resistant and high strength tungsten alloy part, characterized in that: The formula of the tungsten alloy part is calculated by mass percentage, with a total mass of 100%, including 88-94% tungsten, 3-7% nickel, 2-3% iron, 0.2-1% rhenium, 0.2-1% cobalt, and the rest being unavoidable impurities; Wherein, the mass ratio of rhenium to cobalt is 1:

1.

2. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: Firstly, metal powders selected according to the formula of the tungsten alloy part are mixed to obtain mixed powder, and the mixed powder is subjected to cold isostatic pressing to obtain a compact; Shaping the compact to obtain a shaped compact; Sintering the shaped blank to obtain a sintered blank; The sintered blank is subjected to hot isostatic pressing and then machined to obtain a target alloy part.

3. The preparation method according to claim 2, characterized in that: The average particle size of the metal powder is 2.0-4.0 μm, and the purity is above 99.95%; the mixing time is 20-40 hours.

4. The preparation method according to claim 2, characterized in that: The pressure of the cold isostatic pressing treatment is 190-240 MPa, and the holding time is 10-30 min.

5. The preparation method according to claim 2, characterized in that: The sintering is carried out in a mixed atmosphere of argon and hydrogen, and the ratio of argon to hydrogen is 3-4:

1.

6. The preparation method according to claim 2, characterized in that: The sintering comprises the following steps: firstly heating to 180-250°C, keeping the temperature at 180-250°C for 1-4 hours, then heating to 1200-1300°C, keeping the temperature at 1200-1300°C for 1-4 hours, then heating to 1400-1500°C for sintering, and the sintering time is 1-3 hours.

7. The preparation method according to claim 6, characterized in that: The heating rate is 50-100°C / h.

8. The preparation method according to claim 2, characterized in that: The hot isostatic pressing treatment pressure is 120-180 MPa, the temperature is 1200-1400° C., and the holding time is 3-5 hours.

9. A high temperature resistant and high strength tungsten alloy part obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the high temperature resistant and high strength tungsten alloy part as claimed in claim 9 in a single crystal silicon growth furnace.