A method for additively manufacturing nickel-based high-temperature alloy

Abstract

The present invention belongs to the technical field of nickel-based high-temperature alloys, and relates to a method for additive manufacturing of nickel-based high-temperature alloys. The present invention prepares a nickel-based high-temperature alloy precursor powder by ball-milling TC4 alloy and mixing it evenly with GH4169 alloy; and then prepares a nickel-based high-temperature alloy by laser melting deposition of the nickel-based high-temperature alloy precursor powder. The present invention significantly improves the hardness and mechanical properties of the deposited GH4169 alloy by adding TC4 alloy, and the tensile strength can reach 1213.01MPa while the elongation does not decrease significantly.

Description

Technical Field

[0001] The present invention relates to the technical field of nickel-based high-temperature alloys, and in particular to a method for additively manufacturing a nickel-based high-temperature alloy. Background Art

[0002] GH4169 alloy is currently the most widely used nickel-based high-temperature alloy with excellent strength, corrosion resistance, creep resistance and high fatigue life in the range of -253 to 650℃. It is known as the "universal alloy" and is widely used in aircraft engine turbine disks and blades, oil pipelines, nuclear industry structural parts, etc. This alloy is a precipitation-strengthened deformation high-temperature alloy with a high degree of alloying. Traditional vacuum induction melting is prone to alloying element segregation, resulting in metallurgical defects such as black spots and white spots, which affect the performance of the alloy.

[0003] Laser additive manufacturing technology has the characteristics of high cooling rate and high temperature gradient, which is very suitable for the forming of nickel-based high-temperature alloys such as GH4169 that are prone to component segregation. However, this technology also causes the deposited structure of GH4169 alloy to be mostly coarse columnar crystals that penetrate multiple deposition layers.

[0004] In addition, current research focuses on the effect of alloying on the microstructure and properties of GH4169 alloy prepared by vacuum induction melting, and the effect of alloying on the microstructure and properties of GH4169 alloy prepared by laser melting deposition needs further investigation. From the perspective of mechanical properties, although the additively formed GH4169 alloy has high toughness, its strength is not ideal, which limits its further development and application. Therefore, it is particularly important to further improve the strength of GH4169 alloy, improve its comprehensive mechanical properties, and study the evolution of microstructure with alloying. Summary of the invention

[0005] The purpose of the present invention is to provide a method for additive manufacturing of a nickel-based high-temperature alloy. TC4 and GH4169 have similar melting points and thermal expansion coefficients that are not much different. The alloying degree of the GH4169 alloy is improved by adding TC4 alloy to solve the problems existing in the above-mentioned prior art, thereby achieving an improvement in the strength of the GH4169 alloy and improving its comprehensive mechanical properties.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a method for additively manufacturing a nickel-based high-temperature alloy, the steps comprising:

[0008] The TC4 alloy is ball-milled and evenly mixed with the GH4169 alloy to prepare a nickel-based high-temperature alloy precursor powder;

[0009] The nickel-based high-temperature alloy precursor powder is prepared by laser melting deposition to obtain the nickel-based high-temperature alloy.

[0010] Furthermore, the mass percentage of TC4 alloy in the nickel-based high-temperature alloy precursor powder is 1% to 8%.

[0011] Furthermore, the mixing is carried out by ball milling alloying method.

[0012] After mixing by ball milling alloying method, fine TC4 particles are evenly attached to the surface of GH4169 alloy powder.

[0013] Furthermore, the particle size of the TC4 alloy is 80 to 300 μm.

[0014] Furthermore, the particle size of the TC4 alloy after ball milling is 1 to 8 μm.

[0015] Furthermore, the particle size of the GH4169 alloy is 30 to 150 μm.

[0016] Furthermore, the laser power of the laser melting deposition is 1200-2000W, the scanning speed is 360-600mm / min, and the powder feeding rate is 4-9g / min. Preferably, the laser power is 1200W, the scanning speed is 360mm / min, and the powder feeding rate is 8.2g / min.

[0017] Furthermore, the laser melting deposition is performed under the protection of an inert atmosphere.

[0018] Preferably, the inert atmosphere is an argon atmosphere.

[0019] The second technical solution of the present invention is to provide a nickel-based high-temperature alloy prepared by the above method.

[0020] Technical solution three of the present invention: Provide a method for improving the mechanical properties of nickel-based high-temperature alloys, the steps comprising:

[0021] The nickel-based high-temperature alloy is prepared by using TC4 alloy and GH4169 alloy as nickel-based high-temperature alloy precursor powders through laser melting deposition.

[0022] Furthermore, the mass percentage of TC4 alloy in the nickel-based high-temperature alloy precursor powder is 1% to 8%.

[0023] Furthermore, the TC4 alloy is a TC4 alloy that has been subjected to ball milling treatment.

[0024] Preferably, the particle size of the ball mill is 1 to 8 μm.

[0025] Furthermore, the particle size of the GH4169 alloy is 30 to 150 μm.

[0026] Furthermore, the laser power of the laser melting deposition is 1200-2000W, the scanning speed is 360-600mm / min, and the powder feeding rate is 4-9g / min. Preferably, the laser power is 1200W, the scanning speed is 360mm / min, and the powder feeding rate is 8.2g / min.

[0027] Furthermore, the laser melting deposition is performed under the protection of an inert atmosphere.

[0028] Preferably, the inert atmosphere is an argon atmosphere.

[0029] The fourth technical solution of the present invention is to provide the application of TC4 alloy in improving the mechanical properties of GH4169 alloy manufactured by laser additive manufacturing.

[0030] The present invention discloses the following technical effects:

[0031] The addition of TC4 alloy in the laser melting deposited GH4169 alloy did not change the microstructure of the deposited alloy. The bottom of the alloy deposited layer was mainly coarse columnar crystals, and the upper part was mainly fine equiaxed crystals. However, the addition of TC4 alloy effectively refined the size of the deposited grains and brittle Laves phase of the alloy, causing the Laves phase to transform from a continuous long chain to a dispersed short rod, and the aspect ratio decreased from 9.2 to 2.6.

[0032] The present invention significantly improves the hardness and mechanical properties of the deposited GH4169 alloy by adding TC4 alloy, and the tensile strength can reach 1213.01 MPa while the elongation does not decrease significantly.

[0033] The addition of TC4 alloy can effectively replace Al and Ti alloying. During the deposition process, TC4 alloy melts, and its main components Ti and Al fully dissolve into the GH4169 alloy melt, participate in solidification and microstructure formation, increase the solidification rate of the alloy deposition molten pool, reduce element segregation, promote the precipitation of strengthening phases γ′ and γ″, and improve the hardness and mechanical properties of the deposited alloy.

[0034] When laser melting and depositing GH4169 alloy, the addition of TC4 alloy can play the role of grain refinement strengthening, solid solution strengthening and precipitation strengthening. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1SEM images of GH4169 alloy, TC4 alloy, TC4 alloy ball-milled powder and nickel-based high-temperature alloy precursor powder in Example 1, wherein (a) is GH4169 alloy, (b) is TC4 alloy, (c) is TC4 alloy ball-milled powder, and (d) is nickel-based high-temperature alloy precursor powder in Example 1;

[0037] Figure 2 The macrostructure morphology of the nickel-based high-temperature alloy of the single-pass single-layer deposition layer prepared in Comparative Example 1 and Examples 1 to 4, wherein: (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, (e) 8TC4 / GH4169;

[0038] Figure 3 The macrostructure morphology of the nickel-based high-temperature alloy of the single-pass multi-layer deposition layer prepared in Comparative Example 1 and Examples 1 to 4, wherein: (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, (e) 8TC4 / GH4169;

[0039] Figure 4 The microstructure morphology of the bottom of the nickel-based high-temperature alloy of the single-pass single-layer deposition layer prepared in Comparative Example 1 and Examples 1 to 4, wherein: (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, (e) 8TC4 / GH4169;

[0040] Figure 5 The statistical results of the primary dendrite arm spacing of columnar crystals of single-pass single-layer deposition layers GH4169, 1TC4 / GH4169, 3TC4 / GH4169, 5TC4 / GH4169 and 8TC4 / GH4169;

[0041] Figure 6 EBSD analysis results of single-channel single-layer deposited layer samples of GH4169 and 5TC4 / GH4169, where (a) is the inverse pole figure of GH4169, (b) is the pole figure of GH4169, (c) is the inverse pole figure of 5TC4 / GH4169, and (d) is the pole figure of 5TC4 / GH4169;

[0042] Figure 7 XRD patterns and detailed patterns in the range of 49.5-51.5° of GH4169, 1TC4 / GH4169, 3TC4 / GH4169, 5TC4 / GH4169 and 8TC4 / GH4169, wherein (a) is the XRD pattern and (b) is the detailed pattern in the range of 49.5-51.5°;

[0043] Figure 8 The microstructure SEM images and selected EDS points of Comparative Example 1 and Examples 1 to 4, where (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, (e) 8TC4 / GH4169;

[0044] Fig. 9 TEM images of the microstructures of deposited GH4169 and 5TC4 / GH4169 alloys, where (a) GH4169, (b) 5TC4 / GH4169;

[0045] Fig.10 TEM images of dislocations in the deposited GH4169 and 5TC4 / GH4169 alloys, where (a) GH4169, (b) 5TC4 / GH4169;

[0046] Fig.11 The microhardness of the deposited GH4169 alloy with different TC4 alloy contents;

[0047] Fig.12 1 and 2 are stress-strain curves of the alloy samples of Examples 1 to 3 and Comparative Example 1. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0049] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0050] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0051] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0052] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0053] In the specific implementation manner of the present invention, the TC4 alloy and GH4169 alloy used are both commercially available products in powder form. Both original alloy powders have good sphericity, smooth surface and no obvious defects. Among them, the particle size of the TC4 alloy is about 100 μm, and the main chemical components are shown in Table 1. The particle size of the GH4169 alloy is about 50 μm, and the main chemical components are shown in Table 2.

[0054] Table 1 Chemical composition of TC4 alloy

[0055]

[0056] Table 2 Chemical composition of GH4169 alloy

[0057]

[0058] In a specific embodiment of the present invention, the substrate material used for additive manufacturing is 316 stainless steel, the substrate size is 160mm×160mm×20mm, the sample is deposited on the 160mm×160mm surface, the substrate surface is polished smooth with sandpaper to remove the surface oxide layer, and then the substrate surface is wiped and cleaned with acetone, rinsed with alcohol and blown dry for use.

[0059] Example 1

[0060] The steps for additive manufacturing of nickel-based high-temperature alloys are:

[0061] S1, crushing the TC4 alloy powder into fine particles (the particle size after crushing is about 3 μm) by a single-tank planetary ball mill, recorded as TC4 alloy ball-milled powder;

[0062] S2, uniformly mixing the TC4 alloy ball-milled powder and the GH4169 alloy powder in a mass ratio of 1:99 by continuous tumbling and collision in a three-dimensional mixer to obtain a GH4169 alloy preformed powder with fine TC4 particles uniformly attached to the surface, which is recorded as a nickel-based high-temperature alloy precursor powder;

[0063] S3. Using nickel-based high-temperature alloy precursor powder as raw material, additive manufacturing was carried out using Zhongke Yuchen RC-LMD-8060 coaxial powder feeding laser melting deposition equipment. The laser power was 1200W, the scanning speed was 360mm / min, and the powder feeding rate was 8.2g / min. During the additive manufacturing process, the printing chamber was vacuumed and filled with high-purity argon as a protective gas (the oxygen content was controlled to be kept below 50ppm), and single-channel single-layer and single-channel multi-layer deposited nickel-based high-temperature alloys were prepared, which were recorded as 1TC4 / GH4169.

[0064] Example 2

[0065] Compared with Example 1, the only difference is that in step S2, the mass ratio of TC4 alloy ball-milled powder to GH4169 alloy powder is 3:97, and the prepared single-pass single-layer and single-pass multi-layer deposited nickel-based high-temperature alloys are recorded as 3TC4 / GH4169.

[0066] Example 3

[0067] Compared with Example 1, the only difference is that in step S2, the mass ratio of TC4 alloy ball-milled powder to GH4169 alloy powder is 5:95, and the prepared single-pass single-layer and single-pass multi-layer deposited nickel-based high-temperature alloys are recorded as 5TC4 / GH4169.

[0068] Example 4

[0069] Compared with Example 1, the only difference is that in step S2, the mass ratio of TC4 alloy ball-milled powder to GH4169 alloy powder is 8:92, and the prepared single-pass single-layer and single-pass multi-layer deposited nickel-based high-temperature alloys are recorded as 8TC4 / GH4169.

[0070] Comparative Example 1

[0071] The steps for additive manufacturing of nickel-based high-temperature alloys are:

[0072] Using GH4169 alloy powder as raw material, additive manufacturing was carried out using the Zhongke Yuchen RC-LMD-8060 coaxial powder feeding laser melting deposition equipment. The laser power was 1200W, the scanning speed was 360mm / min, and the powder feeding rate was 8.2g / min. During the additive manufacturing process, the printing chamber was vacuumed and filled with high-purity argon as a protective gas (the oxygen content was controlled to be kept below 50ppm), and single-channel single-layer and single-channel multi-layer deposited nickel-based high-temperature alloys were prepared, recorded as GH4169.

[0073] Test example

[0074] Figure 1The SEM images of GH4169 alloy, TC4 alloy, TC4 alloy ball-milled powder and nickel-based superalloy precursor powder in Example 1 are shown in Figure 1, where (a) is GH4169 alloy, (b) is TC4 alloy, (c) is TC4 alloy ball-milled powder, and (d) is nickel-based superalloy precursor powder in Example 1. Figure 1 It can be seen that after the TC4 alloy ball-milled powder and the GH4169 alloy powder are uniformly mixed by continuous tumbling and collision in the three-dimensional mixer, the TC4 alloy ball-milled powder is uniformly attached to the surface of the GH4169 alloy.

[0075] Figure 2 The macroscopic structures of the nickel-based high-temperature alloys of the single-pass single-layer deposited layers prepared in Comparative Example 1 and Examples 1 to 4 are as follows: (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, and (e) 8TC4 / GH4169. Figure 2 It can be seen that the increase in TC4 alloy content slightly increases the dilution rate of the GH4169 alloy deposition pool. The addition of TC4 alloy leads to an increase in the heat release of the alloying reaction of the nickel-based high-temperature alloy precursor powder in the molten pool, an increase in the overall temperature of the molten pool, and a greater depth of remelting.

[0076] Figure 3 The macrostructure morphology of the single-pass multi-layer deposited nickel-based high-temperature alloy prepared in Comparative Example 1 and Examples 1 to 4, where (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, and (e) 8TC4 / GH4169. Figure 3 It can be seen that when the number of sedimentary layers is large, the sedimentary layer of GH4169 becomes tilted and the deposition cannot proceed stably; the sedimentary layers of 1TC4 / GH4169 and 3TC4 / GH4169 are seriously widened. Overall, the overall morphology of the sedimentary layer of 5TC4 / GH4169 is better.

[0077] Figure 4 The microstructure morphology of the bottom of the nickel-based high-temperature alloy of the single-pass single-layer deposition layer prepared in Comparative Example 1 and Examples 1 to 4, where (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, (e) 8TC4 / GH4169. Figure 4 It can be seen that the coarse columnar crystals at the bottom of the sedimentary layer grow from bottom to top, and their direction is almost vertical to the bottom of the sedimentary layer.

[0078] The average value method was used to measure the primary dendrite arm spacing of the experimental alloy. The results are as follows: Figure 5 shown. Figure 5The statistical results of the primary dendrite arm spacing of columnar crystals of single-pass single-layer deposition layers GH4169, 1TC4 / GH4169, 3TC4 / GH4169, 5TC4 / GH4169 and 8TC4 / GH4169 are shown in Figure 2. Figure 5 It can be seen that the primary dendrite arm spacing of the columnar crystals at the bottom of the deposited layers of GH4169, 1TC4 / GH4169, 3TC4 / GH4169, 5TC4 / GH4169 and 8TC4 / GH4169 are 5.6μm, 3.9μm, 3.6μm, 3.5μm and 4.5μm respectively, and the primary dendrite arm spacing of the coarse columnar crystals of the alloy decreases as a whole with the addition of TC4 alloy. The cooling rate during solidification is an important factor affecting the dendrite spacing. When the cooling rate increases, the dendrite growth time is shortened, and the dendrite spacing decreases accordingly. Therefore, the addition of TC4 alloy helps to increase the solidification rate of the alloy deposition molten pool and obtain a more beneficial structure for performance.

[0079] The nickel-based high-temperature alloys prepared in Examples 1 to 4 still exhibit the structural characteristics of the conventional deposited GH4169 alloy. The bottom of the deposited layer is mainly coarse columnar crystals, and the upper part is mainly fine equiaxed crystals. The bands between the layers are clearly visible in the single-pass multi-layer deposited layers, but the coarse columnar crystals run through the multi-layer deposited layers, indicating that the metallurgical bonding between the deposited layers is good, ensuring the continuity of the alloy structure growth and the bonding strength between the layers.

[0080] In general, 5TC4 / GH4169 shows a good deposition effect. The single-channel single-layer deposition samples of GH4169 and 5TC4 / GH4169 were selected for EBSD analysis. The results are as follows: Figure 6 shown.

[0081] Figure 6 The EBSD analysis results of single-channel single-layer deposited layer samples of GH4169 and 5TC4 / GH4169, where (a) is the inverse pole figure of GH4169, (b) is the pole figure of GH4169, (c) is the inverse pole figure of 5TC4 / GH4169, and (d) is the pole figure of 5TC4 / GH4169. Due to the difference in materials used for the substrate and the deposited layer, the substrate is fine equiaxed crystals, while the deposited layer is thick columnar crystals growing from bottom to top, and its growth direction develops along the normal line of the deposited layer boundary toward the inside and top of the deposited layer, as shown by Figure 6It can be seen that in both (a) and (c), there is a phenomenon of epitaxial growth of coarse columnar crystals interrupted by smaller grains. This is because the Marangoni convection affects the temperature gradient, which hinders the growth of columnar crystals. In addition, the maximum size of columnar crystals in the GH4169 alloy shown in (a) can reach 225μm, and the maximum size of columnar crystals in the 5TC4 / GH4169 alloy shown in (c) is 175μm. The addition of TC4 alloy refines the grains of the deposited GH4169 alloy, which is beneficial to the improvement of the mechanical properties of the alloy. The reason for grain refinement is that the addition of TC4 alloy introduces more heterogeneous elements such as Ti and Al, forming a larger composition supercooling during solidification, and increasing nucleation sites. In addition, it can be seen from the pole figures shown in (b) and (d) that the maximum pole densities of the deposited GH4169 and 5TC4 / GH4169 alloys are 4.87 and 3.17, respectively, which means that the grain growth of the two alloys does not show a preferred orientation, that is, the addition of TC4 has no effect on the grain growth orientation of the GH4169 alloy.

[0082] Figure 7 XRD patterns and detailed patterns in the range of 49.5-51.5° of GH4169, 1TC4 / GH4169, 3TC4 / GH4169, 5TC4 / GH4169 and 8TC4 / GH4169, wherein (a) is the XRD pattern and (b) is the detailed pattern in the range of 49.5-51.5°. Figure 7 (a) XRD analysis results show that the deposited TC4 / GH4169 alloy is mainly composed of matrix γ phase, and diffraction peaks corresponding to the four crystal planes (111)γ, (200)γ, (220)γ, and (311)γ are detected. No other phases are detected; (b) The diffraction peaks shown show that compared with the GH4169 alloy, the diffraction peaks of the (200)γ crystal plane of the alloy with TC4 added have a certain degree of left shift, that is, θ decreases. According to the Bragg formula: 2dsinθ=nλ (d is the crystal plane spacing, θ is the angle between the incident X-ray and the corresponding crystal plane, λ is the wavelength of the X-ray, and n is the diffraction order), it can be seen that the decrease in θ means that the crystal plane spacing d increases, that is, the addition of TC4 alloy leads to an increase in the crystal plane spacing of the alloy, indicating that the lattice is distorted and has a strengthening effect on the matrix. This is the reason why atoms such as Ti and Al in TC4 are dissolved into the matrix, that is, the addition of TC4 leads to an increase in the solid solubility of γ phase atoms and a strengthening of solid solution strengthening.

[0083] Figure 8 The microstructure SEM images and selected EDS points of Comparative Example 1 and Examples 1 to 4, where (a) GH4169, (b) 1TC4 / GH4169, (c) 3TC4 / GH4169, (d) 5TC4 / GH4169, and (e) 8TC4 / GH4169. Figure 8It can be seen that white precipitates are distributed in the alloy matrix. Among them, the white precipitates of GH4169 alloy are in the form of long chains with an aspect ratio of about 9.2. After the addition of TC4, the white chain precipitates in the alloy matrix are refined, and the morphology gradually changes to discontinuous short rods, and its aspect ratio is also significantly reduced. When the addition amount of TC4 alloy is 5wt.%, the aspect ratio of the white phase is about 2.6.

[0084] right Figure 8 The EDS points selected for the gray-black matrix and white precipitate phase of the alloy were analyzed. The results are shown in Table 3. It can be seen that the Ni, Fe, and Cr contents in the gray-black area are at a high level, with the Ni content in the range of 44-53wt.%, the Fe content in the range of 20-24wt.%, and the Cr content in the range of 19-21wt.%, while the Nb content is relatively low, only about 3%. In contrast, the Nb content in the white area is much higher than that in the gray-black area, reaching more than 20wt.%, but the Ni, Fe, and Cr contents are relatively low. In addition, the L→γ+Laves eutectic transformation is a typical structural change that occurs in the late solidification of the GH4169 alloy. It can be judged from this that the gray-black area is the matrix γ phase and the white area is the brittle Laves phase (Cr2Nb). On the other hand, from the EDS analysis results of points A, C, E, G, and I, it can be seen that the content of solid-dissolved Ti in the matrix γ phase increases with the increase in the addition of TC4 alloy. The more solid solution of Ti causes the γ phase lattice distortion, which in turn leads to an increase in the interplanar spacing. The results explain Figure 7 (b) The reason why the diffraction peak shifts to the left in the XRD pattern.

[0085] Table 3

[0086]

[0087] Fig. 9 TEM images of the microstructures of deposited GH4169 and 5TC4 / GH4169 alloys, (a) GH4169, (b) 5TC4 / GH4169. Fig. 9 It can be seen that except Figure 7 The XRD patterns shown are Figure 8 In addition to the phases found in the SEM image shown, other phases appeared in the TEM image, which were white granular or ellipsoidal. They can be determined to be strengthening phases γ′(Ni3(Al,Ti)) and γ″(Ni3Nb), among which the granular phase is γ′ and the ellipsoidal phase is γ″. Compared with GH4169 and 5TC4 / GH4169, the contents of strengthening phases γ′ and γ″ in the deposited 5TC4 / GH4169 alloy are much higher than those in GH4169, that is, the addition of TC4 increases the contents of strengthening phases γ′ and γ″ in the GH4169 alloy, which will be beneficial to the improvement of the mechanical properties of the alloy.

[0088] Fig.10TEM images of dislocations in deposited GH4169 and 5TC4 / GH4169 alloys, (a) GH4169, (b) 5TC4 / GH4169. The high solidification rate, molten pool disturbance, and volume change of laser melting deposition cause dislocations to form due to insufficient release of thermal stress and structural stress during solidification. The appearance of dislocations is beneficial to the improvement of alloy strength. Fig.10 It can be seen from (a) and (b) in the figure that the dislocation density of the 5TC4 / GH4169 alloy is higher, that is, the addition of TC4 can increase the dislocation density in the deposited structure of the GH4169 alloy. The reason is that the alloy composition is more complex and the cooling rate during solidification is greater, which leads to an increase in the dislocation density of the alloy after solidification, which is also beneficial to the improvement of the alloy strength.

[0089] The microhardness test was carried out on the alloy samples of Examples 1 to 4 and Comparative Example 1 to explore the effect of TC4 alloy addition on the mechanical properties of the deposited GH4169 alloy. Five different points were taken for testing on each sample, and the results were averaged. The results are shown in Fig.11 shown.

[0090] Fig.11 The microhardness of the deposited GH4169 alloy with different TC4 alloy contents. Fig.11 It can be seen that the microhardness of the GH4169 alloy sample is 296.2HV. With the increase of TC4 alloy addition, the microhardness of the sample shows an upward trend. When the addition amount is 0-5wt.%, the microhardness of the sample increases slowly, but when the TC4 addition amount reaches 8wt.%, the microhardness of the sample increases greatly, and its hardness value reaches 365.1HV, which is 23.3% higher than that of GH4169. With the increase of TC4 alloy addition amount, the grain structure is refined, and fine grain strengthening is achieved. Secondly, by Fig. 9 It can be clearly seen from the TEM image shown that after adding 5wt.% TC4 alloy, the precipitation amount of γ′ and γ″ strengthening phases in the GH4169 alloy is significantly increased, and the precipitation of more strengthening phases also leads to an increase in the hardness of the alloy. It can be seen that the improvement in the microhardness of the nickel-based high-temperature alloy prepared by the present invention can be attributed to fine grain strengthening and precipitation strengthening.

[0091] The influence of TC4 addition on the room temperature tensile properties of GH4169 alloy was investigated by performing tensile tests on the standard tensile specimens of the alloy specimens of Examples 1 to 3 and Comparative Example 1. The results are as follows: Fig.12 And as shown in Table 4.

[0092] Table 4

[0093]

[0094] Fig.12 The stress-strain curves of the alloy samples of Examples 1 to 3 and Comparative Example 1 are shown in FIG. Fig.12 As can be seen from Table 4, the tensile test results show that the tensile strength of the deposited GH4169 alloy is 1021.58MPa and the elongation is 29.5%. With the addition of TC4 alloy, the strength of the deposited alloy gradually increases but is accompanied by a decrease in plasticity. The deposited tensile strengths of 1TC / GH4169, 3TC / GH4169 and 5TC / GH4169 alloys are 1058.12MPa, 1081.43MPa and 1213.01MPa, respectively, and the elongations are 25.3%, 24.4% and 17.5%, respectively. The tensile strength increased by 3.6%, 5.9% and 18.7%, respectively, and the tensile strength of the alloy increased most significantly when 5wt.% TC4 was added. The mechanical properties results correspond to the microstructure morphology, respectively. The finer the grains, the more grain boundaries, the greater the dislocation density inside the material, the material is subjected to external forces, the deformation is dispersed in more grains, and its strength is also higher. Therefore, TC4 alloy is added in GH4169 alloy to replace the alloying of Ti and Al. During the deposition process, TC4 alloy melts, and its main components Ti and Al are fully dissolved into the GH4169 alloy melt to participate in solidification and the formation of solidification structure. As a result, the solidification rate of the deposition molten pool is improved, the segregation of elements is reduced, and the effects of grain refinement strengthening, solid solution strengthening, and precipitation strengthening are played, which comprehensively improves the mechanical properties of the deposited GH4169 alloy.

[0095] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for additive manufacturing of a nickel-based high-temperature alloy, characterized in that the steps include: The TC4 alloy is ball-milled and evenly mixed with the GH4169 alloy to prepare a nickel-based high-temperature alloy precursor powder; The nickel-based high-temperature alloy precursor powder is prepared by laser melting deposition to obtain the nickel-based high-temperature alloy; The mass percentage of TC4 alloy in the nickel-based high-temperature alloy precursor powder is 1% to 8%; The particle size of the TC4 alloy after ball milling is 1 to 8 μm; the particle size of the GH4169 alloy is 30 to 150 μm.

2. The method according to claim 1, characterized in that The laser power of the laser melting deposition is 1200-2000W, the scanning speed is 360-600mm / min, and the powder feeding rate is 4-9g / min.

3. The method according to claim 1, characterized in that The mixing is performed by ball milling alloying method.

4. The method according to claim 1, characterized in that: The particle size of the precursor powder of the TC4 alloy is 80 to 300 μm.

5. A nickel-based high-temperature alloy prepared by the method according to any one of claims 1 to 3.

6. Application of TC4 alloy in improving the mechanical properties of GH4169 alloy manufactured by laser additive manufacturing, characterized in that: The GH4169 alloy is processed by the method for additive manufacturing of nickel-based high-temperature alloys as claimed in claim 1.

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