B2 phase strengthened multi-principal element alloy for laser additive manufacturing and preparation method thereof

Abstract

The application provides a B2 phase reinforced multi-principal element alloy for laser additive manufacturing and a preparation method thereof, and belongs to the technical field of metal laser additive manufacturing. By introducing Al elements and a small amount of W, Mo, Ta, V or Nb solid solution strengthening elements and trace amounts of B, Y, Ce, Zr or Hf grain boundary strengthening elements, a high volume fraction and excellent strengthening effect of fine B2 precipitated phases can be obtained without impairing the printability of the alloy laser additive manufacturing, the comprehensive mechanical properties of the B2 phase reinforced multi-principal element alloy are significantly improved, and the preparation of a new, high-performance and excellent printing performance B2 phase reinforced multi-principal element alloy by laser additive manufacturing is realized.

Description

Technical Field

[0001] This application belongs to the field of metal laser additive manufacturing technology, and specifically relates to a B2 phase-strengthened multi-principal alloy for laser additive manufacturing and its preparation method. Background Technology

[0002] Laser additive manufacturing (also known as 3D printing) is considered a key driving force of the Fourth Industrial Revolution and a crucial core technology that leading technological powers both domestically and internationally are vying to develop, holding an extremely important strategic development position. The unique forming method of additive manufacturing provides significant advantages for the design and manufacture of complex components, offering a disruptive revolution in fully utilizing the superior properties of materials. However, in the field of metal laser additive manufacturing, the fabrication of high-performance and highly reliable structural components still faces enormous challenges: on the one hand, the printable materials are limited; on the other hand, forming defects are difficult to avoid. The high temperature gradient, rapid melting and solidification processes, and cyclic thermal history unique to additive manufacturing place extremely high demands on alloy selection. Therefore, developing novel, high-performance alloys with excellent printability is one of the important directions for development in this field.

[0003] Face-centered cubic (FCC) multi-principal element alloys offer a novel option and broad prospects for the development of laser additive manufacturing alloys due to their unique solidification characteristics, excellent performance, and wide compositional space. Multi-principal element alloys break away from the traditional design concept of single-element-based metallic materials, exhibiting characteristics such as multi-principal composition, high mixing configuration entropy, and simple phase composition, demonstrating excellent mechanical properties and fracture toughness over a wide temperature range. Existing research shows that single-phase FCC multi-principal element alloys possess good additive printability; the resulting deposited alloys not only exhibit a unique hierarchical structure but also possess superior mechanical properties compared to the as-cast state, achieving simultaneous improvements in strength and plasticity. However, due to the inherent phase composition limitations of FCC multi-principal element alloys, the strength improvement of the resulting deposited alloys is quite limited.

[0004] Therefore, how to design a second-phase (B2) reinforced multi-principal alloy suitable for laser additive manufacturing, so as to achieve a significant improvement in the mechanical properties of multi-principal alloys manufactured by laser additive manufacturing, has become a key problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this application is to provide a B2 phase-reinforced multi-principal alloy for laser additive manufacturing and a method for preparing the same, in order to solve or mitigate at least one of the problems in the prior art.

[0006] Firstly, the technical solution of this application is: a B2 phase-reinforced multi-principal alloy for laser additive manufacturing, wherein the chemical formula of the B2 phase-reinforced multi-principal alloy is Ni. a Co bCr c Al d X e Y f Where X is one or more elements selected from tungsten (W), molybdenum (Mo), tantalum (Ta), vanadium (V), and niobium (Nb), Y is one or two elements selected from boron (B), yttrium (Y), cerium (Ce), zirconium (Zr), and hafnium (Hf), and a, b, c, d, e, and f are the molar percentages of each element, satisfying a = b, c + d = 33%, and 9%, respectively. <d<18%、0<e<3%、0<f<0.025%、e+f<3%、a+b+c+d+e+f=100%。

[0007] Secondly, this application provides a method for preparing the above-mentioned B2 phase-reinforced multi-principal-element alloy for laser additive manufacturing, wherein the preparation method employs laser stereolithography technology and includes:

[0008] Step S1: Preparation and pretreatment of multi-principal element alloy powder

[0009] Multi-principal alloy rods are prepared according to the molar percentage of the multi-principal alloy. Pre-alloyed multi-principal alloy spherical powders are prepared by plasma rotating electrode or vacuum atomization method. The powders are sieved and placed in a vacuum drying oven for vacuum drying. After drying, the powders are taken out after the temperature of the vacuum drying oven drops to room temperature and placed in a vacuum bag for vacuum sealing, ready for printing.

[0010] Step S2, Substrate Surface Treatment

[0011] Stainless steel plates matching the dimensions of the laser stereolithography equipment are selected as the substrate. Before printing, the substrate is sanded with sandpaper to remove the oxide scale on the surface. Then, it is placed in an acetone solution for ultrasonic cleaning to remove surface oil. After ultrasonic cleaning, it is further rinsed with anhydrous ethanol and then dried with cold air for later use.

[0012] Step S3: Debugging and preparation of laser stereolithography equipment

[0013] The laser stereolithography equipment is inspected and cleaned, and initialization preparation is carried out, including the installation and fixing of the substrate measuring machine, adding printing powder to the powder feeding device, charging protective gas, adjusting the powder feeding nozzle and directly adjusting the spot. The oxygen content of the charged protective gas is <2000ppm.

[0014] Step S4: Laser stereolithography of multi-principal-element alloy components

[0015] The geometric parameters of the multi-principal alloy component to be prepared are input into the laser stereolithography equipment. Based on the laser stereolithography process parameters and scanning measurements, the pre-prepared alloy powder is melted by a high-energy laser beam, and the multi-principal alloy component is obtained by point-by-point and layer-by-layer deposition printing.

[0016] In a preferred embodiment of this application, when sieving the powder, powder with a particle size of 45μm to 150μm is selected.

[0017] In a preferred embodiment of this application, the process parameters for the vacuum drying process are: drying temperature of 120℃±10℃ and drying time of 12h.

[0018] In a preferred embodiment of this application, the laser stereolithography process parameters are as follows: laser power P is 1200W~2500W, scanning rate v is 6mm / s~12mm / s, spot diameter d is 3mm~5mm, powder feeding rate is 0.5 kg / h~2.0kg / h, overlap rate is 50%, and Z-axis lift is determined based on the single-pass single-layer deposition experiment height; the scanning strategy is bidirectional weaving and 90° interlayer rotation scanning.

[0019] Thirdly, this application provides a method for preparing the above-mentioned B2 phase-reinforced multi-principal alloy for laser additive manufacturing, wherein the preparation method employs laser melting forming technology and includes:

[0020] Step S1: Preparation and pretreatment of multi-principal element alloy powder

[0021] Multi-principal alloy rods are prepared according to the molar percentage of the multi-principal alloy. Pre-alloyed multi-principal alloy spherical powders are prepared by plasma rotating electrode or vacuum atomization method. The powders are sieved and placed in a vacuum drying oven for vacuum drying. After drying, the powders are taken out after the temperature of the vacuum drying oven drops to room temperature and placed in a vacuum bag for vacuum sealing, ready for printing.

[0022] Step S2, Substrate Surface Treatment

[0023] Stainless steel plates matching the size of the selective laser melting equipment are selected as the substrate. Before printing, the substrate is sanded with sandpaper to remove the oxide scale on the surface. Then, it is placed in an acetone solution for ultrasonic cleaning to remove surface oil. After ultrasonic cleaning, it is further rinsed with anhydrous ethanol and then dried with cold air for later use.

[0024] Step S3: Multi-principal alloy construction modeling and import

[0025] Create a model of the multi-principal element alloy component using the 3D modeling software supporting the selective laser melting equipment, and typeset the multi-principal element alloy component to be printed to ensure its reasonable arrangement within the substrate. Secondly, create and edit the data file of the material, and set the corresponding forming process parameters for the multi-principal element alloy component. Then, use the slicing software to slice the model of the multi-principal element alloy component under the set forming process parameters, and import the obtained sliced model into the selective laser melting equipment.

[0026] Step S4, commissioning and preparation of the selective laser melting equipment

[0027] Inspect and clean the selective laser melting equipment, and perform initialization preparations, including substrate measurement and installation fixation, scraper installation and debugging, printing powder addition, protective gas filling, and substrate preheating. Among them, the oxygen content of the filled protective gas is <200 ppm;

[0028] Step S5, laser selective melting to form the B2-phase strengthened multi-principal element alloy

[0029] Select the file to be printed and start processing and printing. According to the set selective laser melting forming process parameters and scanning strategy, melt the multi-principal element alloy powder point by point and layer by layer to obtain the multi-principal element alloy component.

[0030] In the preferred embodiment of the present application, when sieving the powder, powders with a particle size of 15 μm to 53 μm are selected.

[0031] In the preferred embodiment of the present application, the process parameters of the vacuum drying treatment are: drying temperature is 120°C ± 10°C, and drying time is 12 h.

[0032] In the preferred embodiment of the present application, the selective laser melting forming process parameters are: laser power P is 160 W to 360 W, scanning speed v is 600 mm / s to 1400 mm / s, spot diameter d is 60 μm to 80 μm, scanning spacing h is 60 μm to 80 μm, powder layer thickness t is 30 μm to 50 μm; the scanning strategy is two-way weaving and 67° rotation scanning between layers.

[0033] In the preferred embodiment of the present application, it further includes: performing aging treatment on the multi-principal element alloy component after selective laser melting printing at 700°C to 1100°C for a holding time of 0.5 h to 144 h, and performing water cooling after the holding is completed.

[0034] This application provides a novel, high-performance, and printable B2-phase-reinforced multi-principal alloy for laser additive manufacturing, and its preparation method. Based on the NiaCobCrc multi-principal FCC alloy system, by introducing Al element and small amounts of W, Mo, Ta, V or Nb solid solution strengthening elements, and trace amounts of B, Y, Ce, Zr or Hf grain boundary strengthening elements, a high volume fraction of fine B2 precipitates with excellent strengthening effect is obtained without compromising the printability of the alloy in laser additive manufacturing. This significantly improves the comprehensive mechanical properties of the B2-phase-reinforced multi-principal alloy, realizing the preparation of a novel, high-performance, and printable B2-phase-reinforced multi-principal alloy for laser additive manufacturing. Attached Figure Description

[0035] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0036] Figure 1 This is a schematic diagram of the powder morphology when preparing multi-principal element alloys using the laser stereolithography process in this application.

[0037] Figure 2 This is a schematic diagram showing the change in hardness as a function of deposition height for multi-principal-element alloy bulk samples prepared by the laser stereolithography process in this application.

[0038] Figure 3 This is a schematic diagram of the longitudinal section of the scanning electron microscope microstructure of the multi-principal element alloy bulk sample prepared by the laser stereolithography process in this application.

[0039] Figure 4 A schematic diagram comparing the stress-strain curves of a multi-principal-element alloy block sample prepared by the laser stereolithography process in the application with its as-cast room temperature tensile stress-strain curve.

[0040] Figure 5 A schematic diagram of the powder morphology when preparing multi-principal element alloys using laser melting process in the selected area of ​​the application.

[0041] Figure 6 Optical micrograph of the multi-principal-element alloy bulk sample prepared by the selected area laser melting process in this application.

[0042] Figure 7 This diagram illustrates the variation of density with process parameters for multi-principal-element alloy bulk samples prepared by the selected area laser melting process in this application.

[0043] Figure 8 A schematic diagram comparing the multi-principal element alloy bulk sample prepared by the selected area laser melting process in this application with its as-cast room temperature tensile stress-strain curve.

[0044] Figure 9A schematic diagram of the hardness curves of multi-principal-element alloy bulk samples prepared by laser melting process in the selected area of ​​the application after aging treatment at different temperatures.

[0045] Figure 10 Scanning electron microscope (SEM) images of multi-principal-element alloy bulk samples prepared by the selected area laser melting process in this application after aging at 850℃ for 1 hour.

[0046] Figure 11 A schematic diagram of the room temperature tensile stress-strain curve of a multi-principal element alloy block sample prepared by the selected area laser melting process in this application after aging treatment at 850℃ / 1h. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0048] The purpose of this application is to overcome the problem of limited strength of FCC multi-principal alloys in laser additive manufacturing, and to propose a novel, high-performance, and printable B2 phase-reinforced multi-principal alloy suitable for laser additive manufacturing. At the same time, it provides a preparation method and heat treatment scheme for the B2 phase-reinforced multi-principal alloy, realizing the preparation of a novel B2 phase-reinforced multi-principal alloy with high density, no cracks, and excellent comprehensive mechanical properties.

[0049] This application first provides a B2 phase-reinforced multi-principal alloy suitable for laser additive manufacturing, wherein the chemical formula of the B2 phase-reinforced multi-principal alloy is Ni. a Co b Cr c Al d X e Y f Where X is one or more elements selected from tungsten (W), molybdenum (Mo), tantalum (Ta), vanadium (V), and niobium (Nb), and Y is one or two elements selected from boron (B), yttrium (Y), cerium (Ce), zirconium (Zr), and hafnium (Hf); a, b, c, d, e, and f represent the molar percentages of each element, satisfying a = b, c + d = 33%, and 9%, respectively. <d<18%、0<e<3%、0<f<0.025%、e+f<3%、a+b+c+d+e+f=100%。

[0050] In addition, this application also provides a method for preparing the B2 phase-strengthened multi-principal-element alloy, which includes preparation using laser stereolithography and preparation using selective laser melting.

[0051] In the first embodiment of this application, the method for preparing the B2 phase-reinforced multi-principal-element alloy using laser stereolithography technology includes the following steps:

[0052] Step S1: Preparation and pretreatment of multi-principal element alloy powder

[0053] Based on the above molar percentages of the multi-principal alloy, multi-principal alloy rods were prepared using corresponding metal raw materials. Pre-alloyed multi-principal alloy spherical powders (purity up to 99.9%) were prepared using a plasma rotating electrode or vacuum atomization method. The powders were sieved, and powders with a particle size of 45μm~150μm were selected. Typical morphologies are shown below. Figure 1 As shown. After sieving, the pre-formed alloy powder is placed in a vacuum drying oven for vacuum drying to prevent moisture from affecting the sample molding quality. The drying temperature is set to 120℃±10℃ and the drying time is 12 hours. After the heat treatment is completed, the powder is removed after the temperature of the vacuum drying oven drops to room temperature, placed in a vacuum bag, and vacuum sealed, ready for printing.

[0054] Step S2, Substrate Surface Treatment

[0055] 316L stainless steel plate, which is compatible with the size of the laser stereolithography equipment, is selected as the base material. Before molding, the base material needs to be sanded with sandpaper to remove the oxide scale on the surface. Then, it is placed in an acetone solution for ultrasonic cleaning to remove surface oil. After ultrasonic cleaning, it is further rinsed with anhydrous ethanol and then dried with cold air for later use.

[0056] Step S3: Debugging and preparation of laser stereolithography equipment

[0057] The laser stereolithography equipment is inspected and cleaned, and initialization preparation is carried out, including the installation and fixing of the substrate measuring machine, the addition of printing powder to the powder feeding device, the introduction of protective gas (oxygen content <2000ppm), the adjustment of the powder feeding nozzle and the direct adjustment of the spot, etc. High-purity argon (Ar) is used as the protective gas and the powder feeding gas.

[0058] Step S4: Laser stereolithography of the B2 phase-reinforced multi-principal element alloy

[0059] The geometric parameters of the multi-principal alloy component to be prepared are input into the laser stereolithography equipment. The printing process parameters, laser scanning path, and powder feeding rate are set. Under the control of the CNC system, the pre-prepared alloy powder conveyed to the spot through the coaxial powder feeding nozzle is melted by the high-energy laser beam. The B2 phase reinforced multi-principal alloy component with characteristic size and shape is realized by point-by-point and layer-by-layer deposition.

[0060] In this application, the process parameters for preparing the alloy using laser stereolithography are as follows: laser power P is 1200W~2500W, scanning rate v is 6mm / s~12mm / s, spot diameter d is 3mm~5mm, powder feed rate is 0.5 kg / h~2.0kg / h, overlap rate is 50%, and the Z-axis lift is determined based on the single-pass single-layer deposition experiment height. Furthermore, the scanning strategy during laser stereolithography employs bidirectional weaving and 90° interlayer rotation scanning to obtain multi-principal element alloy components after undergoing laser stereolithography deposition cycle heat history treatment.

[0061] Based on the set laser stereolithography process parameters and scanning strategy, B2 phase-reinforced multi-principal alloy powder is melted and deposited point by point and layer by layer to prepare bulk samples. By controlling the elemental composition of the multi-principal alloy and optimizing the forming process parameters, the microstructure of the multi-principal alloy printing can be optimized and its mechanical properties improved, achieving integrated precision forming of B2 phase-reinforced multi-principal alloy with high density, good printability, and excellent comprehensive mechanical properties.

[0062] As shown in Table 1, this embodiment of the application uses three different laser stereolithography process parameters to prepare a Ni-specific material. 32.49 Co 32.49 Cr 20 Al 13 W1Mo1B 0.01 Y 0.01 B2 phase reinforced multi-principal element alloy bulk sample.

[0063] Table 1 Laser Stereoforming Process Parameters

[0064] sample Laser power (W) Scan rate (mm / s) Spot diameter (mm) Powder feeding rate (kg / h) Floor height (mm) 1# 2500 6 3 1.908 0.6 2# 2500 10 3 1.908 0.3 3# 1500 6 3 1.908 0.3

[0065] This application conducted room temperature hardness tests on three samples along the deposition direction, and the results are as follows: Figure 2 As shown, based on the hardness results, the optimal process parameters among the three sets of process parameters are determined to be: laser power 2500W, scanning speed 10mm / s, spot diameter 3mm, powder feeding rate 1.908kg / h, Z-axis lift 0.3mm, and overlap rate 50%.

[0066] This application uses laser confocal microscopy (OM) and scanning electron microscopy (SEM) to observe the sample (Ni) formed under the above-mentioned optimal process parameters. 32.49 Co 32.49 Cr 20 Al 13 W1Mo1B 0.01 Y 0.01 Microstructures, such as Figure 3As shown in the figure, the multi-principal element alloy has good forming quality and no defects such as cracks were observed in the distribution. Furthermore, the sample prepared by laser stereolithography has a clear B2 phase distribution.

[0067] In addition, this application also conducted room temperature tensile property tests on samples prepared under optimal process parameters, such as... Figure 4 As shown, the sample (DED-ed) achieved a yield strength of 750 MPa, a tensile strength of 1050 MPa, and an elongation of 36%. Compared to traditional cast samples (As-cast), the Ni sample prepared using laser stereolithography technology... 32.49 Co 32.49 Cr 20 Al 13 W1Mo1B 0.01 Y 0.01 Multi-principal alloys exhibit excellent strength and ductility.

[0068] In the second embodiment of this application, the method for preparing the B2 phase-strengthened multi-principal-element alloy using selective laser melting forming technology includes the following steps:

[0069] Step S1: Preparation and pretreatment of multi-principal element alloy powder

[0070] Multi-principal alloy rods were prepared from the corresponding metal raw materials according to the molar percentage. Pre-alloyed multi-principal alloy spherical powders were prepared using a plasma rotating electrode or vacuum atomization method. The powders were sieved, and powders with a particle size of 15μm~53μm were selected. Typical morphologies are shown below. Figure 5 As shown. After sieving, the pre-formed alloy powder is placed in a vacuum drying oven for vacuum drying to prevent moisture from affecting the sample molding quality. The drying temperature is set to 120℃±10℃ and the drying time is 12 hours. After the heat treatment is completed, the powder is removed after the temperature of the vacuum drying oven drops to room temperature, placed in a vacuum bag, and vacuum sealed, ready for printing.

[0071] Step S2, Substrate Surface Treatment

[0072] 316L stainless steel plate matching the size of the selective laser melting equipment is selected as the base material. Before forming, the base material needs to be sanded with sandpaper to remove the oxide scale on the surface. Then, it is placed in an acetone solution for ultrasonic cleaning to remove surface oil. After ultrasonic cleaning, it is further rinsed with anhydrous ethanol and then dried with cold air for later use.

[0073] Step S3, Preparation for Modeling the Selected Area Laser Melting Equipment

[0074] The Magics 3D modeling software, which is compatible with the selective laser melting equipment, is used to create multi-principal element alloy component models and to arrange the components to be printed to ensure that they are reasonably arranged within the substrate. Next, material data files are created and edited, and corresponding forming process parameters are set for each component. After that, slicing software is used to slice the model with the set parameters, and the resulting sliced ​​model is imported into the selective laser melting equipment.

[0075] Step S4: Debugging and preparation of selective laser melting equipment

[0076] The selective laser melting equipment was inspected and cleaned, and initialization preparations were carried out, including substrate measurement and installation, scraper installation and debugging, printing powder addition, protective gas filling (oxygen content <200ppm) and substrate preheating.

[0077] Step S5: Selective laser melting to form the B2 phase-reinforced multi-principal alloy.

[0078] Select the file to print and start the printing process. Based on the set laser melting forming process parameters and scanning strategy, multi-principal alloy powder is melted point by point and layer by layer to prepare multi-principal alloy components.

[0079] Furthermore, the selective laser melting (SLM) process parameters are as follows: laser power P = 160 W ~ 360 W, scanning rate v = 600 mm / s ~ 1400 mm / s, spot diameter d = 60 μm ~ 80 μm, scanning spacing h = 60 μm ~ 80 μm, and powder layer thickness t = 30 μm ~ 50 μm. Furthermore, the SLM scanning strategy employs bidirectional weaving and 67° interlayer rotation scanning.

[0080] In a preferred embodiment of this application, to promote the precipitation of fine B2 phase with high density and high volume fraction, the multi-principal alloy prepared by selective laser melting (SLM) is heat-treated. The heat treatment method includes: heating the B2 phase-reinforced multi-principal alloy prepared by SLM to 700℃~1100℃ and holding it at that temperature for 0.5h~144h for aging treatment, followed by water cooling after the holding period. By heat-treating the B2 phase-reinforced multi-principal alloy prepared by SLM, the precipitation of a large amount of fine B2 phase with high volume fraction can be effectively promoted, while obtaining an incompletely recrystallized microstructure, further improving the mechanical properties of the B2 phase-reinforced multi-principal alloy prepared by SLM, and realizing the preparation of a high-strength and high-toughness multi-principal alloy.

[0081] When preparing B2 phase-reinforced multi-principal alloys using selective laser melting, by controlling the elemental composition of the multi-principal alloys and optimizing the forming process parameters, it is possible to achieve integrated precision forming of B2 phase-reinforced multi-principal alloys with high density, printability, and excellent mechanical properties.

[0082] Table 2 shows the specific composition of Ni prepared using different selective laser melting process parameters in this embodiment of the application. 32.49 Co 32.49 Cr 20 Al 13 W1Mo1B 0.01 Y 0.01 The density test results of the deposited samples of the B2 phase-reinforced multi-principal alloy bulk sample are as follows: Figure 6 As shown.

[0083] Table 2 Selective Laser Melting Process Parameters

[0084] sample Laser power (W) Scan rate (mm / s) Scanning spacing (μm) Powder coating thickness (μm) <![CDATA[Volume energy density (J / mm 3 )]]> 1 160 800 80 30 83.33 2 180 800 80 30 93.75 3 200 800 80 30 104.17 4 220 800 80 30 114.58 5 240 800 80 30 125 6 160 1000 80 30 66.67 7 180 1000 80 30 75 8 200 1000 80 30 83.33 9 220 1000 80 30 91.67 10 240 1000 80 30 100 11 160 1200 80 30 55.56 12 180 1200 80 30 62.5 13 200 1200 80 30 69.44 14 220 1200 80 30 76.39 15 240 1200 80 30 83.33

[0085] Microstructure characterization of selected-area laser melting-formed multi-principal-element alloy bulk materials was performed using laser confocal microscopy (OM), such as... Figure 7 As shown, the multi-principal element alloy has good formability, with no defects such as cracks observed, and its microstructure is finer and more uniform compared to the as-cast alloy (prepared by vacuum arc melting).

[0086] Table 2 shows that the optimal process parameters among the above sets of process parameters are: laser power of 220W, scanning rate of 1000mm / s, scanning spacing of 80μm, and powder layer thickness of 30μm.

[0087] In addition, such as Figure 8 As shown, this application describes a multi-principal element alloy sample (Ni) under the above-mentioned optimal process parameters. 32.49 Co 32.4 9Cr 20 Al 13 W1Mo1B 0.01 Y 0.01 Mechanical property tests were conducted on the sample (SLM-ed), which showed a yield strength of 840 MPa, a tensile strength of 1100 MPa, and an elongation of 38% at room temperature. The sample with the same composition (Ni) 32.49 Co 32.49 Cr 20 Al 13 W1Mo1B 0.01 Y 0. 01 The as-cast multi-principal alloy has a yield strength of 528 MPa, a tensile strength of 990 MPa, and an elongation of 32%, indicating that the mechanical properties of the multi-principal alloy under these process parameters are significantly improved compared to the as-cast multi-principal alloy.

[0088] Finally, this application also tested multi-principal alloys formed by laser selective melting and heat treatment, such as... Figure 9The hardness results of the multi-principal element alloy samples formed by selective laser melting shown are obtained after heat treatment at different temperatures for 1 hour. Figure 9 It can be found that the multi-principal element alloy sample after heat treatment at 850℃ and holding for 1 hour has the highest hardness, achieving further strengthening.

[0089] like Figure 10 Scanning electron microscope (SEM) images of multi-principal element alloy samples formed by selective laser melting (SLM) after heat treatment at 850℃ for 1 hour show partial recrystallization of the deposited structure and the formation of numerous fine B2 precipitates in the FCC matrix. Figure 11 As shown, the room temperature tensile properties of multi-principal alloy samples formed by selective laser melting were tested after heat treatment. The test results showed that the strength of the multi-principal alloy after heat treatment was greatly improved, with a yield strength of 985 MPa, a tensile strength of 1550 MPa, and an elongation of 28.8%. This room temperature tensile property is the highest performance level of multi-principal alloys manufactured by laser additive manufacturing to date.

[0090] This application provides a novel, high-performance, and printable B2-phase-reinforced multi-principal alloy for laser additive manufacturing, and its preparation method. Based on the NiaCobCrc multi-principal FCC alloy system, by introducing Al element and small amounts of W, Mo, Ta, V or Nb solid solution strengthening elements, and trace amounts of B, Y, Ce, Zr or Hf grain boundary strengthening elements, a high volume fraction of fine B2 precipitates with excellent strengthening effect is obtained without compromising the printability of the alloy in laser additive manufacturing. This significantly improves the comprehensive mechanical properties of the B2-phase-reinforced multi-principal alloy, realizing the preparation of a novel, high-performance, and printable B2-phase-reinforced multi-principal alloy for laser additive manufacturing.

[0091] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A B2 phase-strengthened multi-principal element alloy for laser additive manufacturing, characterized in that, The chemical formula of the B2 phase-strengthened multi-principal alloy is Ni. a Co b Cr c Al d X e Y f Where X is one or more elements selected from tungsten (W), molybdenum (Mo), tantalum (Ta), vanadium (V), and niobium (Nb), Y is one or two elements selected from boron (B), yttrium (Y), cerium (Ce), zirconium (Zr), and hafnium (Hf), and a, b, c, d, e, and f are the molar percentages of each element, satisfying a = b, c + d = 33%, and 9%, respectively. <d<18%、0<e<3%、0<f<0.025%、e+f<3%、a+b+c+d+e+f=100%。 2. A method for preparing a B2 phase-reinforced multi-principal-element alloy for laser additive manufacturing as described in claim 1, characterized in that, The preparation method employs laser stereolithography technology, including: Step S1: Preparation and pretreatment of multi-principal element alloy powder Multi-principal alloy rods are prepared according to the molar percentage of the multi-principal alloy. Pre-alloyed multi-principal alloy spherical powders are prepared by plasma rotating electrode or vacuum atomization method. The powders are sieved and placed in a vacuum drying oven for vacuum drying. After drying, the powders are taken out after the temperature of the vacuum drying oven drops to room temperature and placed in a vacuum bag for vacuum sealing, ready for printing. Step S2, Substrate Surface Treatment Stainless steel plates matching the dimensions of the laser stereolithography equipment are selected as the substrate. Before printing, the substrate is sanded with sandpaper to remove the oxide scale on the surface. Then, it is placed in an acetone solution for ultrasonic cleaning to remove surface oil. After ultrasonic cleaning, it is further rinsed with anhydrous ethanol and then dried with cold air for later use. Step S3: Debugging and preparation of laser stereolithography equipment The laser stereolithography equipment is inspected and cleaned, and initialization preparation is carried out, including the installation and fixing of the substrate measuring machine, adding printing powder to the powder feeding device, charging protective gas, adjusting the powder feeding nozzle and directly adjusting the spot. The oxygen content of the charged protective gas is <2000ppm. Step S4: Laser stereolithography of multi-principal-element alloy components The geometric parameters of the multi-principal alloy component to be prepared are input into the laser stereolithography equipment. Based on the laser stereolithography process parameters and scanning measurements, the pre-prepared alloy powder is melted by a high-energy laser beam, and the multi-principal alloy component is obtained by point-by-point and layer-by-layer deposition printing.

3. The preparation method according to claim 2, characterized in that, When sieving the powder, select powder with a particle size of 45μm to 150μm.

4. The preparation method according to claim 2, characterized in that, The process parameters for the vacuum drying process are: drying temperature of 120℃±10℃ and drying time of 12h.

5. The preparation method according to claim 2, characterized in that, The laser stereolithography process parameters are as follows: laser power P is 1200W~2500W, scanning rate v is 6mm / s~12mm / s, spot diameter d is 3mm~5mm, powder feeding rate is 0.5 kg / h~2.0kg / h, overlap rate is 50%, and Z-axis lift is determined based on the single-pass single-layer deposition experiment height; the scanning strategy is bidirectional weaving and 90° interlayer rotation scanning.

6. A method for preparing a B2 phase-reinforced multi-principal-element alloy for laser additive manufacturing as described in claim 1, characterized in that, The preparation method employs laser melting and forming technology, including: Step S1: Preparation and pretreatment of multi-principal element alloy powder Multi-principal alloy rods are prepared according to the molar percentage of the multi-principal alloy. Pre-alloyed multi-principal alloy spherical powders are prepared by plasma rotating electrode or vacuum atomization method. The powders are sieved and placed in a vacuum drying oven for vacuum drying. After drying, the powders are taken out after the temperature of the vacuum drying oven drops to room temperature and placed in a vacuum bag for vacuum sealing, ready for printing. Step S2, Substrate Surface Treatment Stainless steel plates matching the size of the selective laser melting equipment are selected as the substrate. Before printing, the substrate is sanded with sandpaper to remove the oxide scale on the surface. Then, it is placed in an acetone solution for ultrasonic cleaning to remove surface oil. After ultrasonic cleaning, it is further rinsed with anhydrous ethanol and then dried with cold air for later use. Step S3: Multi-principal alloy construction modeling and import Create a model of the multi-principal element alloy component using the 3D modeling software supporting the selective laser melting equipment, and typeset the multi-principal element alloy component to be printed to ensure that the multi-principal element alloy component to be printed is reasonably arranged within the substrate. Secondly, create and edit the data file of the material, and set the corresponding forming process parameters for the multi-principal element alloy component. After that, use the slicing software to slice the model of the multi-principal element alloy component under the set forming process parameters, and import the obtained sliced model into the selective laser melting equipment. Step S4, Debugging and Preparation of the Selective Laser Melting Equipment Inspect and clean the selective laser melting equipment, and perform initialization preparations, including substrate measurement and installation fixation, scraper installation and debugging, addition of printing powder, filling of protective gas, and substrate preheating. Among them, the oxygen content of the filled protective gas is <200 ppm. Step S5, Laser Selective Melting to Form the B2-Phase Strengthened Multi-Principal Element Alloy Select the file to be printed and start processing and printing. According to the set selective laser melting forming process parameters and scanning strategy, melt the multi-principal element alloy powder point by point and layer by layer to obtain the multi-principal element alloy component.

7. The preparation method according to claim 6, characterized in that, When sieving the powder, select powder with a particle size of 15 μm to 53 μm.

8. The preparation method according to claim 6, characterized in that, The process parameters of the vacuum drying treatment are: drying temperature is 120°C ± 10°C, and drying time is 12 h.

9. The preparation method according to claim 6, characterized in that, The selective laser melting forming process parameters are: laser power P is 160 W to 360 W, scanning speed v is 600 mm / s to 1400 mm / s, spot diameter d is 60 μm to 80 μm, scanning spacing h is 60 μm to 80 μm, and powder layer thickness t is 30 μm to 50 μm; the scanning strategy is two-way weaving and 67° rotation scanning between layers.

10. The preparation method according to claim 6, characterized in that, It also includes: Perform aging treatment on the multi-principal element alloy component after selective laser melting printing at 700°C to 1100°C for 0.5 h to 144 h, and perform water cooling after the insulation ends.

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