Novel 3D printing nickel-based superalloy and preparation method thereof

Abstract

The invention relates to a novel 3D printing nickel-based superalloy and a preparation method thereof, and belongs to the technical field of metal materials, and the nickel-based superalloy comprises the following chemical elements in percentage by mass: 20.5-24% of W (Cr), 18-22% of W (Co), 0.01-0.2% of W (C), 0.01-0.2% of W (Zr), 1.0-3.0% of W (W), 0.01-1.0% of W (Mo), 1.5-2.5% of W (Al), 3.0-5.0% of W (Ti), 0.5-1.5% of W (Nb), 1-1.5% of W (Ta) and the balance of Ni. By improving the alloy components and optimizing the alloy forming process, the high-temperature bearing capacity and the high-temperature mechanical property of the nickel-based high-temperature alloy can be remarkably improved, and the nickel-based high-temperature alloy can have good oxidation resistance and high-temperature corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and in particular to a novel 3D printing nickel-based high-temperature alloy and a preparation method thereof. Background Art

[0002] High-temperature structural materials are key materials for aerospace engines. In modern advanced aerospace engines, high-temperature alloys account for 40% to 60% of the total weight of the engine, which plays a great role in ensuring the safe operation of the engine. The temperature of the hot end of the fourth-generation aerospace engine (especially the combustion chamber and turbine) is in the range of 1400 to 1650°C, and nickel-based and cobalt-based high-temperature alloys are generally used for preparation. The higher the temperature of the turbine, the higher the efficiency, thus achieving better fuel economy. The operating temperature of the engines of the new generation of aerospace vehicles is higher, and traditional high-temperature alloys are difficult to meet the requirements of the new generation of aircraft. It is urgent to explore new high-temperature alloy systems. New high-temperature structural materials must have higher comprehensive properties, such as strength, toughness, creep performance and environmental characteristics, and lower density.

[0003] Nickel-based high-temperature alloys, due to their excellent comprehensive performance and development cost advantages, have become an ideal choice for manufacturing key components such as turbine blades, guide vanes, turbine disks, combustion chambers, etc. in aircraft engines and gas turbines.

[0004] The temperature bearing capacity of nickel-based high-temperature alloys directly affects the performance and service life of the engine. The development of high-temperature alloys with higher temperature bearing capacity can not only improve the efficiency of the engine and reduce energy consumption, but also meet the needs of a wider range of high-temperature applications.

[0005] The organic combination of additive manufacturing technology and nickel-based high-temperature alloys can not only more efficiently manufacture more complex structural components in aircraft engines, but also manufacture nickel-based high-temperature alloy components with good comprehensive performance, which can realize material-structure-performance integrated manufacturing to meet the needs of the aerospace field for additively manufactured metal components.

[0006] The invention patent with the publication number CN116377286A eliminates the microcrack defects generated during the laser powder bed fusion forming process of traditional nickel-based superalloys by setting the composition of Ni, W, Mo, Al, Ti, Nb, and Ta, thereby improving the mechanical properties. However, the raw materials of the elements Ni, Nb, Ta, Co, W, C, and Ti used in the smelting process of this invention are all the simple substances of the corresponding elements. The melting points of refractory metals tungsten (melting point 3410 °C), niobium (melting point 2447 °C), and tantalum (melting point 2996 °C) are too high. When directly preparing the alloy material by the melting and mixing method, it is difficult to melt, and it is easy to cause segregation of refractory metals in the powder. The invention patent with the publication number CN115889808A discloses using three nickel-based superalloy powders, namely GH3536, GH3625, and GH4169, as raw materials. Aiming at the problem of easy cracking during the printing and forming process of superalloys, by optimizing the printing parameters and adding a second selective laser melting additive manufacturing process, the purpose of reducing the cracking of printed parts is achieved. However, this technology does not clearly indicate that it helps to improve the high-temperature mechanical properties of the alloy. The invention patent with the publication number CN114959332A realizes the suppression of internal crack generation in the alloy through an additive manufacturing preparation method of preheating the substrate and powder bed and combining the powder melting and scanning process. However, the repeated preheating steps of this invention will promote the dynamic recrystallization process of the grains in the nickel-based superalloy matrix, and the coarse recrystallized grains significantly reduce the mechanical properties of the alloy.

[0007] Therefore, based on the above research foundation and application status, there is an urgent need to develop a new type of nickel-based superalloy powder material suitable for large-scale industrial production and 3D printing processes, which can fully meet the requirements of high temperature-bearing capacity, high-temperature mechanical properties, high-temperature oxidation resistance, and thermal corrosion resistance for applications in the aerospace field. Summary of the Invention

[0008] The purpose of the present invention is to provide a new type of 3D printing nickel-based superalloy and its preparation method to meet the needs of the aerospace field for additive manufacturing metal components.

[0009] To achieve the above purpose, the present invention provides the following technical solutions:

[0010] In the first aspect of the present invention, a new type of 3D printing nickel-based superalloy powder is provided. The chemical elements in the nickel-based superalloy powder are in mass percentages as follows:

[0011] W(Cr): 20.5 - 24%, W(Co): 18 - 22%, W(C): 0.01 - 0.2%, W(Zr): 0.01 - 0.2%, W(W): 1.0 - 3.0%, W(Mo): 0.01 - 1.0%, W(Al): 1.5 - 2.5%, W(Ti): 3.0 - 5.0%, W(Nb): 0.5 - 1.5%, W(Ta): 1 - 1.5%, and the balance is Ni.

[0012] In a preferred embodiment, the contents of the Cr element and the Co element satisfy the following relationship: W(Cr):W(Co) = (1 - 1.3):1.

[0013] In a preferred embodiment, the contents of the W element and the Mo element satisfy the following relationship: W(W) + W(Mo): 1.0 - 4.0%.

[0014] In a preferred embodiment, the contents of the Al element and the Ti element satisfy the following relationship: W(Al):W(Ti) = 1:2, and W(Ti) + W(Al) < 7.0%.

[0015] In a preferred embodiment, the contents of the Al element, the Ti element, the Nb element, and the Ta element satisfy the following relationship: W(Al) + W(Ti) + W(Nb) + W(Ta): 8.0 - 12.0%.

[0016] The second aspect of the present invention provides a new type of 3D printing nickel-based superalloy, which is prepared by using the new type of 3D printing nickel-based superalloy powder.

[0017] The third aspect of the present invention provides a preparation method of a new type of 3D printing nickel-based superalloy, and the new type of nickel-based superalloy powder is subjected to 3D printing.

[0018] In a preferred embodiment, the specimen made after 3D printing is subjected to heat treatment.

[0019] In a preferred embodiment, the heat treatment temperature is 1000 - 1200 °C, the heat preservation time is 1 - 8 h, and it is cooled with the furnace or rapidly cooled.

[0020] The fourth aspect of the present invention provides the application of the new type of 3D printing nickel-based superalloy in additive manufacturing technology.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] By improving the alloy composition and optimizing the preparation process, the present invention can significantly improve the high-temperature bearing capacity and high-temperature mechanical properties of the nickel-based superalloy, and can also endow it with good oxidation resistance and high-temperature corrosion resistance.

[0023] I. High-temperature load-bearing and high-temperature mechanical properties

[0024] 1) The present invention mainly adds three chemical elements of nickel, chromium, and cobalt, supplemented by a small amount of chemical elements such as tungsten, molybdenum, aluminum, titanium, niobium, tantalum, and zirconium. By means of optimizing and adjusting the composition, high-melting-point compounds are formed and uniformly distributed in the alloy, and the volume fraction of γ'-phase in the alloy is increased, thereby realizing the improvement of the high-temperature load-bearing capacity and high-temperature mechanical properties of the nickel-based superalloy;

[0025] 2) The present invention adopts the method of feeding low-melting-point master alloys for refractory metals with high melting points such as molybdenum, tungsten, niobium, and tantalum, reducing the difficulty of metal melting, facilitating melting and diffusion, and greatly reducing the melting difficulty of the component alloy and the risk of composition segregation in the final nickel-based superalloy powder. On the other hand, the present invention correspondingly reduces the melting temperature, and effectively suppresses element segregation on the basis of satisfying the melting and dispersion of the master alloy. Therefore, through the improvement of raw materials and the optimization of the melting process, the uniform distribution of γ'-strengthening phase in the nickel-based superalloy is realized, and the uniform distribution of fine and dispersed MC strengthening phase in the nickel-based superalloy is realized, which has the effect of uniformly dispersing the internal stress generated during the printing process, thereby reducing the risk of stress cracking;

[0026] 3) Applying the theory of metal solidification and element segregation, rationally design the content of alloying elements. By adding an appropriate amount of aluminum element, during the solidification process of the alloy, the solubility of Al will decrease with the decrease of temperature, causing the enrichment of Al element at the dendrite boundary and grain boundary, promoting the formation of a continuous thin film phase. At the same time, the continuous shrinkage of the matrix will generate large residual stresses at the dendrite boundary and grain boundary. As the temperature further decreases, the B2 phase gradually precipitates at the dendrite boundary and grain boundary positions and gradually undergoes spinodal decomposition, decomposing into island-like B2 phase and Cr-rich BCC phase. The phase transformation behavior induced by spinodal decomposition will promote the molar volume expansion, and the asymmetric distribution of intermetallic compound phases will introduce more geometric dislocations. The stress fields generated by both aspects can jointly offset part of the residual tensile stress, changing the residual stress distribution state at the dendrite boundary and grain boundary positions, and even changing from the tensile stress state to the compressive stress state, thereby effectively inhibiting the alloy cracking behavior. By adding an appropriate amount of titanium element, Ti atoms can replace aluminum atoms in γ′-Ni3Al to form Ni3(Al,Ti). Under certain aluminum content conditions, as the Ti content increases, the number of γ′ phases increases, resulting in the improvement of the alloy's low-temperature and high-temperature properties. At the same time, the Ti atoms existing in the γ′ phase can significantly increase the antiphase domain boundary energy, promoting the strengthening effect caused by the cutting mechanism. At the same time, note that the contents of Al and Ti should satisfy W(Al):W(Ti) = 1:2, W(Ti)+W(Al)<7.0%, to prevent the occurrence of difficult-to-bridge grain boundary cracks during the alloy solidification process due to excessive contents of Al and Ti. The addition of zirconium element reduces grain boundary defects, effectively improves the bonding strength, and reduces the grain boundary diffusion rate, thereby achieving the purpose of slowing down dislocation climb and strengthening the grain boundary. At the same time, Zr segregates at the grain boundary, reducing the interface energy, which can change the morphology of the grain boundary phase, reduce the size of the grain boundary phase, and effectively prevent grain sliding along the grain boundary, thereby improving the alloy's creep life.

[0027] II. Oxidation resistance and high-temperature corrosion resistance

[0028] By adding a relatively high proportion of Cr and Co elements and by limiting the addition ratio of the two, the two can play a synergistic role. The Cr element forms a dense Cr 2 O 3The oxide layer blocks the diffusion of O to the substrate and improves the oxidation resistance of the alloy. At the same time, Cr can also cause lattice distortion in the superalloy substrate, generate elastic stress field strengthening, and promote the solution strengthening effect. The Co element has a higher melting point and can promote the solution effect of chemical elements in the matrix, improving the oxidation resistance, high-temperature corrosion resistance, and thermal and cold fatigue performance of the alloy. At the same time, with the increase of Co content, the stacking fault energy of the Ni-Cr matrix can be continuously reduced, and the corresponding steady-state creep rate can be continuously reduced. Through experiments, it is found that when the element ratio is between W(Cr):W(Co)=(1-1.3):1, the alloy can obtain better comprehensive performance. The addition of Ta has also been confirmed to be able to improve the stability of the γ' phase and improve the hot corrosion resistance of the alloy to a certain extent. Brief Description of the Drawings

[0029] Figure 1 It is the powder electron micrograph of the nickel-based superalloy powder prepared in Example 1 of the present invention;

[0030] Figure 2 It is the as-printed nickel-based superalloy original specimen in Example 1;

[0031] Figure 3 It is the electron micrograph of the internal metallographic structure of the heat-treated state of the nickel-based superalloy specimen printed in Example 1;

[0032] Figure 4 It is the internal metallographic structure photograph of the as-printed nickel-based superalloy original specimen in Comparative Example 4;

[0033] Figure 5 It is the internal metallographic structure photograph of the as-printed nickel-based superalloy original specimen in Comparative Example 5;

[0034] Figure 6 It is the internal metallographic structure photograph of the as-printed nickel-based superalloy original specimen in Comparative Example 6;

[0035] Figure 7 It is the internal metallographic structure photograph of the as-printed nickel-based superalloy original specimen in Comparative Example 7;

[0036] Figure 8 It is the internal metallographic structure photograph of the as-printed nickel-based superalloy original specimen in Comparative Example 8;

[0037] Figure 9 It is the internal metallographic structure photograph of the as-printed nickel-based superalloy original specimen in Comparative Example 9;

[0038] Figure 10 It is the nickel-based superalloy alloy impeller component printed in Example 1. Detailed Embodiments

[0039] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] On the one hand, the present invention provides a new type of 3D printing nickel-based superalloy powder. The chemical elements in the nickel-based superalloy powder are as follows in mass percentage:

[0041] W(Cr): 20.5 - 24%, W(Co): 18 - 22%, W(C): 0.01 - 0.2%, W(Zr): 0.01 - 0.2%, W(W): 1.0 - 3.0%, W(Mo): 0.01 - 1.0%, W(Al): 1.5 - 2.5%, W(Ti): 3.0 - 5.0%, W(Nb): 0.5 - 1.5%, W(Ta): 1 - 1.5%, and the balance is Ni.

[0042] Specifically, in the nickel-based superalloy powder, the contents of Cr element and Co element satisfy the following relationship: W(Cr): W(Co) = (1 - 1.3): 1. The Cr element forms a dense Cr 2 O 3 oxide layer on the alloy surface to block the diffusion of O to the matrix and improve the oxidation resistance of the alloy. At the same time, Cr can also cause lattice distortion in the nickel-based superalloy matrix, generate an elastic stress field strengthening, and promote the solid solution strengthening effect. The Co element has a higher melting point and can promote the solid solution effect of chemical elements in the matrix, improving the oxidation resistance, high-temperature corrosion resistance, and thermal fatigue performance of the alloy. At the same time, with the increase of Co content, the stacking fault energy of the Ni-Cr matrix can be continuously reduced, and the corresponding steady-state creep rate can be continuously reduced.

[0043] The contents of W element and Mo element satisfy the following relationship: W(W) + W(Mo): 1.0 - 4.0%. Tungsten and molybdenum elements can significantly promote the lattice distortion of the nickel-based superalloy matrix, form a long-range stress field, and prevent dislocation movement, thereby improving the yield strength of the alloy. At the same time, tungsten and molybdenum can also improve the coordination relationship between γ and γ' phases and affect the mechanical properties of the alloy.

[0044] The contents of Al element and Ti element satisfy the following relationship: W(Al):W(Ti) = 1:2, and W(Ti)+W(Al)<7.0%. Adding Al element can effectively inhibit the cracking behavior of the alloy. By adding an appropriate amount of Ti element, Ti atoms can replace Al atoms in γ′-Ni3Al to form Ni3(Al,Ti). Under the condition of a certain Al content, as the Ti content increases, the number of γ′ phases increases, resulting in the improvement of the alloy's heat resistance and high-temperature performance. At the same time, the Ti atoms existing in the γ′ phase can significantly increase the antiphase domain boundary energy, promoting the strengthening effect caused by the cutting mechanism. At the same time, the contents of Al and Ti should not be too high to prevent the appearance of grain boundary cracks that are difficult to heal during the solidification process of the alloy due to excessive Al and Ti contents.

[0045] Furthermore, the contents of Al element, Ti element, Nb element and Ta element satisfy the following relationship: W(Al)+W(Ti)+W(Nb)+W(Ta): 8.0 - 12.0%. Nb and Ta elements promote the precipitation strengthening effect by acting on the γ′ phase. At the same time, the dissolution of Ta atoms in the γ′ phase can inhibit the aggregation, growth and dissolution of the γ′ phase, improve the tissue stability of the alloy, and reduce the cracking risk of the alloy to a certain extent. The increase in the content of precipitation strengthening elements in nickel-based superalloys will promote the high alloying of the matrix, reduce the weldability of the powder, and easily cause cracks during the additive manufacturing process. Through experiments, it is found that the ratio of W(Al)+W(Ti)+W(Nb)+W(Ta): 8.0 - 12.0% can effectively balance the comprehensive performance of this alloy.

[0046] The preparation method of the above-mentioned new 3D printing nickel-based superalloy powder includes the following steps:

[0047] S1. Raw material melting: Heat and melt pure metals and master alloy raw materials under vacuum conditions according to the formula;

[0048] During raw material melting, a stepped power increase method is adopted, with a power span of 10 - 120 kW, each power stage is maintained for 10 - 30 min, and the melting process is kept fully stirred. The melting temperature is set at 1550 - 1700 °C, and the melting time is 10 - 60 min. The method of feeding low-melting master alloy reduces the melting temperature compared with the conventional melting temperature. On the basis of satisfying the melting and dispersion of the master alloy, it can effectively inhibit element segregation.

[0049] S2. Atomization powder making: Atomize the melted pre-alloyed metal with inert gas, and the atomization pressure for atomization powder making is 4.0 - 6.0 Mpa.

[0050] S3. Powder screening: Screen and classify the pre-alloyed metal powder prepared in step S2 under an inert gas protection atmosphere; the pressure of the inert gas protection atmosphere is 0.05 - 1.0 MPa, and the particle size range of the screened powder is 15 - 53 μm.

[0051] S4. Heat preservation and drying: Dry the powder screened in step S3.

[0052] The second aspect of the present invention provides a new type of 3D printed nickel-based superalloy, which is prepared from the above-mentioned new type of 3D printed nickel-based superalloy powder.

[0053] The third aspect of the present invention provides a preparation method of a new type of 3D printed nickel-based superalloy, and uses the above-mentioned new type of nickel-based superalloy powder for 3D printing and forming. Import the three-dimensional digital model of the specimen into the 3D printer, and set the printing parameter range as follows:

[0054] Laser power 50 - 300 kW, scanning speed 500 - 2000 mm / s, scanning spacing 0.05 - 0.30 mm, powder spreading layer thickness 0.01 - 0.05 mm. During the powder printing and forming process, monitor the printing status in real time to ensure the printing quality and progress.

[0055] Heat-treat the alloy specimen formed by 3D printing, the heat treatment temperature is 1000 - 1200 °C, the heat preservation time is 1 - 8 h, and cool with the furnace or cool rapidly.

[0056] The fourth aspect of the present invention provides the application of the new type of 3D printed nickel-based superalloy in additive manufacturing technology. By controlling the shape and properties of the new type of 3D printed nickel-based superalloy, parts suitable for industrial applications can be obtained.

[0057] The following further elaborates the present invention in combination with embodiments. Similarly, it should be understood that the following embodiments are only used to further illustrate the present invention, and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are also only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description in this article, rather than being limited to the specific values in the following examples.

[0058] Example 1

[0059] This example provides a new type of 3D printed nickel-based superalloy. The raw material powder used is prepared by the melting and atomization method mentioned in the text. The powder chemical elements are in mass percentage as follows:

[0060] W(Cr): 20.5%, W(Co): 18%, W(C): 0.2%, W(Zr): 0.2%, W(W): 1.0%, W(Mo): 1.0%, W(Al): 2.0%, W(Ti): 4.0%, W(Nb): 0.5%, W(Ta): 1.5%, the balance is Ni. Preparation of the new 3D printing nickel-based superalloy: 3D printing is carried out using the prepared new nickel-based superalloy powder, and the 3D printed specimen is heat-treated. The heat treatment temperature is 1150 °C, the holding time is 6 h, and it is cooled in the furnace.

[0061] Example 2

[0062] This example provides a new 3D printing nickel-based superalloy. The raw material powder used is prepared by the melting atomization method mentioned in the text. The chemical elements of the powder are in mass percentage: W(Cr): 24%, W(Co): 22%, W(C): 0.1%, W(Zr): 0.1%, W(W) 3.0%, W(Mo): 0.5%, W(Al): 2.0%, W(Ti): 4.0%, W(Nb): 1.5%, W(Ta): 1.5%, the balance is Ni.

[0063] Preparation of the new 3D printing nickel-based superalloy: 3D printing is carried out using the prepared new nickel-based superalloy powder, and the 3D printed specimen is heat-treated. The heat treatment temperature is 1200 °C, the holding time is 8 h, and it is cooled in the furnace.

[0064] Example 3

[0065] This example provides a new 3D printing nickel-based superalloy. The raw material powder used is prepared by the melting atomization method mentioned in the text. The chemical elements of the powder are in mass percentage:

[0066] W(Cr): 22%, W(Co): 22%, W(C): 0.1%, W(Zr): 0.1%, W(W): 2.0%, W(Mo): 1.0%, W(Al): 2.0%, W(Ti): 4.0%, W(Nb): 1.0%, W(Ta): 1.0%, the balance is Ni.

[0067] Preparation of the new 3D printing nickel-based superalloy: 3D printing is carried out using the prepared new nickel-based superalloy powder, and the 3D printed specimen is heat-treated. The heat treatment temperature is 1200 °C, the holding time is 3 h, and it is rapidly cooled.

[0068] Comparative Example 1 (low Cr content)

[0069] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0070] In this comparative example, the content of Cr element is lower than that in Example 1. Specifically, in terms of mass percentage: W(Cr) is 17%, and the ratio of W(Cr) to W(Co) is less than 1:1.

[0071] Comparative Example 2 (high Cr content)

[0072] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0073] In this comparative example, the content of Cr element is higher than that in Example 1. Specifically, in terms of mass percentage: W(Cr) is 25%, and the ratio of W(Cr) to W(Co) is higher than 1.3:1.

[0074] Comparative Example 3 (low Co content)

[0075] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0076] In this comparative example, the content of Co element is lower than that in Example 1. Specifically, in terms of mass percentage: W(Co) is 16%.

[0077] Comparative Example 4 (low Al content)

[0078] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0079] In this comparative example, the content of Al element is lower than that in Example 1. Specifically, in terms of mass percentage: W(Al) is 1.0%, and W(Al) + W(Ti) + W(Nb) + W(Ta) < 8.0%.

[0080] Comparative Example 5 (high Al content)

[0081] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0082] In this comparative example, the content of Al element is higher than that in Example 1. Specifically, in terms of mass percentage: W(Al) is 4.0%, and W(Al) + W(Ti) > 7.0%.

[0083] Comparative Example 6 (low Ti content)

[0084] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0085] In this comparative example, the content of Ti element is lower than that in Example 1. Specifically, in terms of mass percentage: W(Ti) is 2.0%, and W(Al) + W(Ti) + W(Nb) + W(Ta) < 8.0%.

[0086] Comparative Example 7 (high Ti content)

[0087] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0088] In this comparative example, the content of Ti element is higher than that in Example 1. Specifically, in terms of mass percentage: W(Ti) is 6.0%, and W(Al) + W(Ti) > 7.0%.

[0089] Comparative Example 8 (low Ta content)

[0090] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0091] In this comparative example, the content of Ta element is lower than that in Example 1. Specifically, in terms of mass percentage: W(Ta) is 0.8%, and W(Al) + W(Ti) + W(Nb) + W(Ta) < 8.0%.

[0092] Comparative Example 9 (pure metal raw materials)

[0093] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0094] In this comparative example, during the raw material melting process, the pure metals are heated and melted under vacuum conditions according to the formula, that is, all metal elements use elemental substances as raw materials. In order to completely melt the alloy, the melting temperature is correspondingly increased. The melting temperature of S1 in this comparative example is about 2000°C.

[0095] Comparative Example 10 (Changing the heat treatment temperature)

[0096] The chemical elements and preparation method of the novel 3D printed nickel-based superalloy provided in this comparative example are substantially the same as those in Example 1. For the sake of brevity, only the differences will be described in detail here.

[0097] In this comparative example, when the 3D printed alloy specimen was heat-treated, it was held at 950 °C for 4 h and then cooled in the furnace to obtain a 3D printed specimen.

[0098] Perform performance tests on the 3D printed specimens prepared in the above examples and comparative examples. The test results are shown in Table 1:

[0099] Table 1 Performance test results of each example and comparative example

[0100]

[0101]

[0102] The nickel-based superalloy specimens prepared through the three examples of the present invention have good mechanical properties: the tensile strength at room temperature ≥ 1400 MPa, the elongation after fracture ≥ 8%; the tensile strength at 900 °C ≥ 550 MPa, the elongation after fracture ≥ 5%; the initial stress at 850 °C is 350 MPa, and the high-temperature creep rupture time ≥ 30 h. Figures 1 - 3 Respectively show the powder electron microscope image of the nickel-based superalloy powder prepared in Example 1, the photo of the original specimen printed with this powder, and the electron microscope image of the internal metallographic structure of the heat-treated state of this original specimen. Figure 10 Show the alloy impeller parts printed with the nickel-based superalloy powder of Example 1.

[0103] It can be seen from the data results of Comparative Examples 1-2 and Example 1 that if the dosage of Cr element is too much or too little, it will lead to a decrease in the room-temperature mechanical properties and high-temperature mechanical properties of the alloy. Because the Cr element mainly cooperates with the Ni element, and the two play a synergistic role. The Cr element forms a dense Cr 2 O 3 oxide layer to block the diffusion of O to the matrix and improve the high-temperature oxidation resistance of the alloy. The Ni element can promote the growth of Cr 2 O 3 and delay the nodular oxidation of the alloy, improving the oxidation resistance and high-temperature corrosion resistance of the alloy. Moreover, when the element content W(Cr):W(Co) = (1-1.3):1, the alloy has the best high-temperature oxidation effect. In the atmospheric environment, during high-temperature use (800-1000 °C), a dense and thin oxide film will form on the surface to prevent further oxidation, and the alloy can maintain good high-temperature mechanical properties.

[0104] From the data results of Comparative Example 3, it can be seen that if the amount of Co in the alloy is too small, the high-temperature performance of the alloy will be significantly reduced. Co has a higher melting point and can promote the solid solution effect of alloy elements in the matrix, which plays an important role in improving the oxidation resistance and high-temperature corrosion resistance of the alloy. Too low Co content is not conducive to exerting the high-temperature performance advantages of the alloy.

[0105] From the data results of Comparative Examples 4-7, it can be seen that if the content and ratio of Al / Ti in the alloy are too high or too low, the high-temperature mechanical properties of the alloy specimen will decrease, and cracking will occur. Figures 4 - 7 The internal metallographic microstructure photos of the corresponding original specimens are shown respectively. During the solidification process of the alloy, the solubility of aluminum decreases with decreasing temperature, causing aluminum to be enriched at the branch grain boundary and grain boundary, promoting the formation of a continuous liquid phase film. At the same time, the continuous contraction of the matrix will produce large residual stresses at the branch grain boundary and grain boundary. As the temperature further decreases, the B2 phase gradually precipitates at the branch grain boundary and grain boundary, and gradually undergoes spinodal decomposition, decomposing into island B2 phase and Cr-rich BCC phase. The phase change behavior induced by spinodal decomposition will promote the molar volume expansion, and the asymmetric distribution of the intermetallic compound phase will introduce more geometric dislocations. The stress fields generated by the two aspects can jointly offset part of the residual tensile stress, change the residual stress distribution state at the dendrite boundary and grain boundary position, and even change from a tensile stress state to a compressive stress state. The addition of Ti element can effectively adjust the existence state of Al in the matrix, thereby effectively inhibiting the cracking behavior of the alloy. Therefore, it is necessary to strictly control the content of Al and Ti in the alloy, and control the Al / Ti ratio to about 1:2.

[0106] From the data results of Comparative Example 8 and Figure 8 It can be seen from the internal metallographic structure photos of the corresponding original specimens that if the Ta content in the alloy is reduced, cracks will appear in the specimens and the plasticity of the alloy will be significantly reduced. This is related to the fact that the Ta atoms dissolved in the γ′ phase can inhibit the state of the γ′ phase. In the alloy structure with low Ta content, the formation of harmful phase TCP structure was found, which seriously damaged the welding performance of the alloy.

[0107] From the data results of Comparative Example 9, it can be seen that if the raw materials are all metal single substances, a very high melting temperature is required, the melting difficulty is extremely high, and the production energy consumption is high; in addition, the mechanical properties and high-temperature mechanical properties of the alloy specimens finally prepared will be reduced. Figure 9The internal metallographic structure photos of the corresponding original specimens are shown. In the preparation method of the present invention, for high-melting-point refractory metals such as W (melting point 3410 °C), Mo (melting point 2620 °C), Nb (melting point 2477 °C), and Ta (melting point 2996 °C), the method of feeding low-melting-point intermediate alloys is adopted, which greatly reduces the melting difficulty of the component alloys. Combining with the equal-power holding melting process: adopting a stepped power increase method, the power span is 10-120 kW, and each power is maintained for 10-30 min to ensure that the molten metal is fully and evenly distributed. According to the actual situation, electromagnetic stirring is added when necessary to facilitate the control of the melting process and the diffusion of chemical elements, and finally greatly reduces the risk of composition segregation in the final superalloy powder. Finally, the alloy powder has a uniform composition, and there are no refractory metal particles or high-melting-point intermediate phase particles, thereby improving the mechanical properties and high-temperature mechanical properties of the alloy specimens, and no cracks occur.

[0108] It can be seen from the data results of Comparative Example 10 that: the heat treatment temperature is lower than the solid solution temperature of the elements inside the alloy, which can greatly promote the precipitation of the second phase, sacrificing the high-temperature strength and elongation after fracture of the material to improve the room-temperature strength of the alloy, resulting in an increase in the room-temperature tensile strength of the alloy and a significant decrease in the high-temperature mechanical properties. And the temperature above 1200 °C is already close to the melting point of the nickel-based superalloy, and there is a safety risk in carrying out the heat treatment. Therefore, 1000-1200 °C is the only suitable heat treatment temperature for this nickel-based superalloy.

[0109] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A new type of 3D printing nickel-based high-temperature alloy powder, characterized in that: The chemical elements in the nickel-based high-temperature alloy powder are calculated by mass percentage: W(Cr): 20.5~24%, W(Co): 18~22%, W(C): 0.01~0.2%, W(Zr): 0.01~0.2%, W(W): 1.0~3.0%, W(M o): 0.01 to 1.0%, W (Al): 1.5 to 2.5%, W (Ti): 3.0 to 5.0%, W (Nb): 0.5 to 1.5%, W (Ta): 1 to 1.5%, and the balance is Ni.

2. The novel 3D printing nickel-based high-temperature alloy powder according to claim 1 is characterized in that: The contents of the Cr element and the Co element satisfy the following relationship: W(Cr):W(Co)=(1-1.3):

1.

3. The novel 3D printing nickel-based high-temperature alloy powder according to claim 1 is characterized in that: The contents of the W element and the Mo element satisfy the following relationship: W(W)+W(Mo): 1.0-4.0%.

4. The novel 3D printing nickel-based high-temperature alloy powder according to claim 1 is characterized in that: The contents of the Al element and the Ti element satisfy the following relationship: W(Al):W(Ti)=1:2, and W(Ti)+W(Al)<7.0%.

5. The novel 3D printing nickel-based high-temperature alloy powder according to claim 4 is characterized in that: The contents of the Al element, the Ti element, the Nb element and the Ta element satisfy the following relationship: W(Al)+W(Ti)+W(Nb)+W(Ta): 8.0-12.0%.

6. A new type of 3D printed nickel-based high-temperature alloy, characterized in that: The 3D printing nickel-based high-temperature alloy powder is prepared using the new type of 3D printing nickel-based high-temperature alloy powder described in any one of claims 1 to 5.

7. The method for preparing the novel 3D printing nickel-based high-temperature alloy according to claim 6, characterized in that: The novel nickel-based high-temperature alloy powder is 3D printed.

8. The method for preparing the novel 3D printing nickel-based high-temperature alloy according to claim 7, characterized in that: The specimens made after 3D printing were heat treated.

9. The method for preparing the novel 3D printing nickel-based high-temperature alloy according to claim 8, characterized in that: The heat treatment temperature is 1000-1200° C., the heat preservation time is 1-8 hours, and the product is cooled with the furnace or rapidly cooled.

10. Application of the new 3D printing nickel-based high-temperature alloy described in claim 6 in additive manufacturing technology.

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