A silver alloy powder, a method of manufacture and a laser selective melting additive manufacturing method

Abstract

The application discloses a silver alloy powder, a preparation method and a laser selective melting additive manufacturing method. The silver alloy powder is a silver copper antimony yttrium alloy powder, and raw materials for forming the silver copper antimony yttrium alloy powder consist of the following components in percentage by mass: Ag 92.5%, Cu 6%-6.9%, Sb 0.5%-1%, and Y 0.1%-0.5%. The AgCuSbY alloy powder prepared by using the Ag-Cu-Sb-Y quaternary alloy with the specific elements and the matching as the raw materials has excellent sphericity, good fluidity and concentrated particle size distribution, is highly suitable for the laser selective melting additive manufacturing process, and makes the density of a SLM (selective laser melting) shaped part close to a theoretical value, the microstructure uniform and small, isotropic and excellent in mechanical properties.

Description

Technical Field

[0001] This application relates to the field of metal additive manufacturing technology, and more specifically, to a silver alloy powder and its preparation method and a laser selective melting additive manufacturing method. Background Technology

[0002] Silver-copper (Ag-Cu) binary eutectic alloys are core alloy materials in traditional high-temperature applications due to their excellent electrical and thermal conductivity and plasticity. However, their high eutectic temperature of 779℃ makes component forming and subsequent precision machining difficult, and their relatively low strength makes them prone to plastic deformation or even structural failure under complex stress or cyclic loading, making them unsuitable for the load-bearing requirements of high-end parts. Adding an appropriate amount of antimony (Sb) to Ag-Cu binary alloys can form a low-melting-point eutectic structure, effectively narrowing the alloy's solidification temperature range. Silver-copper-antimony (Ag-Cu-Sb) alloys are considered ideal materials for key functional components such as precision electronic contacts and electromagnetic devices due to their excellent electrical and thermal conductivity and certain mechanical strength. However, traditional processing methods, such as precision casting and machining, are difficult to manufacture complex internal structural features, and have low material utilization and long production cycles.

[0003] Selective laser melting (SLM) is a 3D printing technology that can manufacture highly complex geometric shapes in a single step with high precision, eliminating the need for traditional step-by-step processing and assembly. This makes it possible to directly manufacture complex silver-based alloy parts. Meanwhile, for the SLM process, the high sphericity and flowability of the powder material used are the primary key technical indicators, as they are fundamental prerequisites for ensuring high density and excellent uniformity in the printed parts.

[0004] However, Ag-Cu-Sb ternary alloy powder particles have poor sphericity and severe adhesion and agglomeration morphological defects, which greatly reduce the powder flowability and loose packing density, leading to problems such as uneven powder layer and bridging during selective laser melting (SLM) powder spreading. This results in the following technical challenges for Ag-Cu-Sb alloys in the SLM process: (1) The alloying elements (Cu, Sb) and Ag matrix are prone to severe element segregation, forming coarse and brittle phases; (2) Poor wettability of the melt pool easily induces spheroidization, forming pores; (3) The inherent huge temperature gradient of SLM leads to high residual stress and hot cracks; (4) Epitaxial growth along the laser scanning direction forms coarse columnar crystals, resulting in poor process adaptability due to the anisotropy of the microstructure and properties. These problems seriously affect the density, performance uniformity, reliability and mechanical properties of the formed parts, making them unable to meet the stringent requirements of high-end precision electronic devices for performance consistency.

[0005] Therefore, there is an urgent need for a comprehensive method that can fundamentally solve the problem of SLM forming of silver-based alloys. Summary of the Invention

[0006] The main objective of this application is to provide a silver alloy powder and its preparation method, as well as a laser selective melting additive manufacturing method, to solve the technical problems of low density, performance uniformity, and mechanical properties of existing silver-based alloy SLM formed parts. It can effectively suppress element segregation and hot cracking, and obtain parts with density close to the theoretical value, uniform and fine microstructure, isotropy, and excellent mechanical properties.

[0007] To achieve the above objectives, the first aspect of this application provides a silver alloy powder, which is a silver-copper-antimony-yttrium alloy powder. The raw materials forming the silver-copper-antimony-yttrium alloy powder are composed of the following components by mass percentage: Ag 92.5%, Cu 6%-6.9%, Sb 0.5%-1%, Y 0.1%-0.5%.

[0008] In some embodiments of this application, the mass ratio of Sb to Y is Sb:Y = (2-10):1, preferably Sb:Y = 5:1.

[0009] In some embodiments of this application, the sphericity of the silver-copper-antimony-yttrium alloy powder is not less than 0.967, wherein the particle size distribution of 38µm-53µm accounts for at least 55% of the total mass.

[0010] In some embodiments of this application, the Hall flow rate of the silver-copper-antimony-yttrium alloy powder is 12.22 s / 50 g to 13.09 s / 50 g.

[0011] The second aspect of this application proposes a method for preparing silver alloy powder, which includes the following steps: using a vacuum induction gas atomization powder preparation device, with an inert gas as the medium, to melt and atomize a silver-copper-antimony-yttrium alloy ingot to obtain spherical silver-copper-antimony-yttrium alloy powder.

[0012] The silver-copper-antimony-yttrium alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 6%-6.9%, Sb 0.5%-1%, Y 0.1%-0.5%.

[0013] In some embodiments of this application, the melting temperature is 1000℃-1200℃; the melting pressure is 0.2bar-0.3bar; and the ultrasonic atomizer vibration frequency is 35kHz-45kHz.

[0014] In some embodiments of this application, the step of sieving the silver-copper-antimony-yttrium alloy powder into a particle size range of 18 μm-53 μm is also included.

[0015] A third aspect of this application proposes a laser selective melting additive manufacturing method, comprising the following steps: using a laser selective melting device, under inert gas protection, 3D printing is performed using the aforementioned silver-copper-antimony-yttrium alloy powder as raw material, so that the silver-copper-antimony-yttrium alloy powder is formed layer by layer to obtain a silver-copper-antimony-yttrium alloy printed component. In particular, a dynamic scanning method with interlayer staggered moving heat source starting points is used for scanning during 3D printing.

[0016] In some embodiments of this application, the dynamic scanning method of interlayer staggered moving heat source starting point refers to changing the position of the laser scanning starting point between two or more adjacent layers during 3D printing by translation or rotation, so as to form staggered scanning starting points.

[0017] In some embodiments of this application, the settings parameters of the laser selective melting device include: laser power of 150W-450W, scanning speed of 200mm / s-1600mm / s, scanning spacing of 0.03mm-0.10mm, and powder thickness of 0.02mm-0.04mm.

[0018] In a fourth aspect of this application, a silver alloy part is proposed, which is a silver-copper-antimony-yttrium alloy part, obtained by the laser selective melting additive manufacturing method described above; The part has a density of at least 98.5%, a hardness of at least 98.47 HV, a tensile strength of at least 313.44 MPa, and an elongation of at least 34%.

[0019] The technical solutions provided by the embodiments of this application may include the following beneficial effects: The silver alloy powder of this application uses a specific ratio of Ag-Cu-Sb-Y quaternary alloy as raw material, with Sb and Y elements added simultaneously to the silver alloy, which work synergistically. Sb element can lower the eutectic temperature of the alloy and form a distinct network / skeleton-like second phase at the grain boundaries, thereby improving the alloy strength; Y element can refine the alloy grains and disperse precipitation, and also improve the morphology of the second phase formed by Sb element, making it more dispersed and uniform, avoiding the continuous distribution of brittle phases; at the same time, the grain boundary purification effect of Y element further improves the grain boundary bonding strength, offsetting the plasticity reduction problem caused by Sb element, thus achieving a simultaneous improvement in both strength and plasticity of the Ag-Cu-Sb-Y quaternary alloy.

[0020] Therefore, due to the optimization of microstructure, strength, and plasticity, the AgCuSbY alloy powder prepared using the above-mentioned Ag-Cu-Sb-Y quaternary alloy ingot as raw material has excellent sphericity (not less than 0.967), good flowability (Hall flow rate not higher than 13.09s / 50g), and concentrated particle size distribution (particles of 18μm-53μm account for more than 55% of the total mass). These characteristics make it highly suitable for laser selective melting additive manufacturing process, providing a high-quality raw material basis for the stable forming of high-precision, high-density parts.

[0021] In the selective laser melting (SLM) additive manufacturing method of this application, the silver-copper-antimony-yttrium alloy powder used has several advantages. First, yttrium not only acts as a purifying agent, deeply removing impurities such as oxygen, sulfur, and hydrogen from the melt, eliminating the root cause of porosity and hot cracking, but also acts as a surface-active element, significantly reducing the surface tension of the melt, fundamentally improving wettability and spreadability during the SLM process, while refining the grains, achieving multiple effects of "purification-modification-refinement". Second, under the ultrafast cooling conditions of SLM, a narrower solidification zone means a shorter liquid / solid two-phase region, which greatly inhibits the solute enrichment and macroscopic segregation of Cu elements at the solidification front, laying the foundation for obtaining a uniform microstructure. Third, the ultrafast cooling rate of SLM results in extremely refined grains, with the second phase formed by Sb and Y being uniformly distributed in an ultrafine dispersed state in the matrix and grain boundaries, without any continuous network brittle phase, resulting in a uniform and dense microstructure. Therefore, the combined effects of grain refinement, dispersion strengthening, and grain boundary purification maximize the alloy's strength while maintaining good ductility, achieving a significant performance breakthrough. Furthermore, SLM ultrafast cooling effectively suppresses elemental segregation and the formation of a continuous network of brittle phases, further amplifying the synergistic strengthening effect of Sb and Y. This allows SLM-printed silver-copper-antimony-yttrium alloy components to maintain ductility while improving both alloy strength and toughness.

[0022] Meanwhile, this invention addresses the thermal stress problem in the SLM forming process by proposing a "dynamic scanning method for the interlayer staggered moving heat source starting point". This process breaks away from the thermal stress accumulation caused by the traditional fixed starting point scanning method. By dynamically dispersing the starting position of the heat source, it achieves effective control of the forming thermal field, avoids thermal stress concentration, and thus effectively suppresses the generation of cracks, ensuring the integrity and high density of the formed part.

[0023] In summary, this SLM method, through the combined addition of Sb and Y elements, the integration of SLM, and the synergistic optimization of the scanning method, aims to effectively suppress elemental segregation and hot cracking. The alloy grains are continuously refined, the number of precipitated phases increases, and their distribution becomes more diffuse and uniform, with no continuous brittle network phases, resulting in a stepwise increase in alloy strength. The silver-copper-antimony-yttrium alloy parts formed by SLM in this invention have a density close to the theoretical value (98.7%), a uniform and fine microstructure, are isotropic, and possess excellent mechanical properties (the Vickers hardness of the silver-copper-antimony-yttrium alloy SLM-printed components reaches 101.96 HV, the tensile strength reaches 313.44 MPa, and the elongation is as high as 41%). This enables the direct manufacturing of high-end precision electronic devices such as precision electronic contacts and electromagnetic devices, which require extremely high performance consistency. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 Ag prepared in Example 1 of this application 92.5 Cu 6.9 Sb 0.5 Y 0.1 Scanning electron microscope image of alloy powder; Figure 2 Ag prepared in Example 2 of this application 92.5 Cu 6.4 Sb 1.0 Y 0.1 Scanning electron microscope image of alloy powder; Figure 3 Ag prepared for Comparative Example 1 of this application 92.5 Cu 7.0 Sb 0.5 Scanning electron microscope image of alloy powder; Figure 4 Ag in Example 1 of this application 92.5 Cu 6.9 Sb 0.5 Y 0.1 Metallographic images of alloy SLM-printed components; Figure 5 For comparison with Example 1 of this application, Ag 92.5 Cu 7.0 Sb 0.5 Metallographic images of alloy SLM-printed components; Figure 6 Metallographic diagrams of silver alloy ingots for blank examples 1-3 of this application; in, Figure 6 (a) is Ag in blank example 1 92.5Cu 6.9 Sb 0.5 Y 0.1 Metallographic diagram of alloy ingot; Figure 6 (b) is Ag in blank example 2 92.5 Cu 7.0 Sb 0.5 Metallographic diagram of alloy ingot; Figure 6 (c) is Ag in blank example 3 92.5 Cu 7.4 Y 0.1 Metallographic diagram of alloy ingot; Figure 7 This application applies to Example 1, Ag 92.5 Cu 6.9 Sb 0.5 Y 0.1 Actual image of an alloy SLM-printed component. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0026] Example 1 A method for preparing silver alloy powder includes the following steps: (1) Cut the silver-copper-antimony-yttrium alloy ingot into small pieces, place them in the crucible of the vacuum induction melting ultrasonic atomization powder making chamber, and adjust the position of the melt nozzle at the lower end of the crucible so that it faces the ultrasonic vibrating plate. The silver-copper-antimony-yttrium alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 6.9%, Sb 0.5%, Y 0.1%; (2) Close the hatch and set the process parameters: melting temperature is 1100 ℃, melting pressure is 0.2 bar, and ultrasonic atomizer frequency is 40 kHz; (3) Evacuate the chamber until the vacuum level reaches 0.45 mbar, then fill it with high-purity argon for gas cleaning, and repeat this operation 5 times; after cleaning, adjust the chamber pressure to the melting pressure of 0.2 bar; (4) Start the program to heat and melt the silver-copper-antimony-yttrium alloy ingot to obtain the alloy melt. The alloy melt drips onto the ultrasonic vibrating plate through the nozzle. Under the high-frequency vibration of the ultrasonic atomizer, it is atomized by high-pressure inert gas. The molten alloy is broken into micron-sized fine droplets and quickly cooled and solidified to form spherical silver-copper-antimony-yttrium alloy powder. (5) Collect and wash the powder, and sieve it with a particle size range of 18μm-53μm.

[0027] The powder parameters of the silver-copper-antimony-yttrium alloy powder obtained by sieving are shown in Table 1.

[0028] Table 1. Powder parameters of silver-copper-antimony-yttrium alloy powder

[0029] It can be seen that the silver-copper-antimony-yttrium alloy powder has a reasonable particle size distribution, mainly concentrated in 25-53µm (250-500 mesh) and 10-18µm (800-1400 mesh). Among them, the particle size distribution of 18μm-53μm accounts for 59.16% of the total mass. This particle size range is very suitable for the requirements of SLM process for powder spreading and melting properties.

[0030] Electron micrographs of the sieved silver-copper-antimony-yttrium alloy powder in this embodiment are shown below. Figure 1 As shown, the powder particles are generally regular spherical or nearly spherical in shape, with smooth surfaces, no obvious cracks, pores or oxide layers, and no obvious satellite spheres, adhesion or irregular fragments.

[0031] Tests showed that the sphericity of the silver-copper-antimony-yttrium alloy powder in this embodiment was not less than 0.987, and the Hall flow rate was 12.22 s / 50g.

[0032] Example 2 A method for preparing silver alloy powder includes the following steps: (1) Cut the silver-copper-antimony-yttrium alloy ingot into small pieces, place them in the crucible of the vacuum induction melting ultrasonic atomization powder making chamber, and adjust the position of the melt nozzle at the lower end of the crucible so that it faces the ultrasonic vibrating plate. The silver-copper-antimony-yttrium alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 6.4%, Sb 1.0%, Y 0.1%; (2) Close the hatch and set the process parameters: melting temperature is 1100 ℃, melting pressure is 0.2 bar, and ultrasonic atomizer frequency is 40 kHz; (3) Evacuate the chamber until the vacuum level reaches 0.45 mbar, then fill it with high-purity argon for gas cleaning, and repeat this operation 5 times; after cleaning, adjust the chamber pressure to the melting pressure of 0.2 bar; (4) Start the program to heat and melt the silver-copper-antimony-yttrium alloy ingot to obtain the alloy melt. The alloy melt drips onto the ultrasonic vibrating plate through the nozzle. Under the high-frequency vibration of the ultrasonic atomizer, it is atomized by high-pressure inert gas. The molten alloy is broken into micron-sized fine droplets and quickly cooled and solidified to form spherical silver-copper-antimony-yttrium alloy powder. (5) Collect and wash the powder, and sieve it with a particle size range of 18μm-53μm.

[0033] After sieving, particles with a size distribution of 18μm-53μm account for 55.53% of the total mass. This particle size range is very suitable for the requirements of SLM process for powder spreading and melting properties.

[0034] Electron micrographs of the sieved silver-copper-antimony-yttrium alloy powder in this embodiment are shown below. Figure 2 As shown, the powder particles are generally regular spherical or nearly spherical in shape, with smooth surfaces, no obvious cracks, pores or oxide layers, and no obvious satellite spheres, adhesion or irregular fragments.

[0035] The sphericity of the silver-copper-antimony-yttrium alloy powder in this embodiment is not less than 0.967, and the Hall flow rate is 13.09 s / 50g.

[0036] Comparative Example 1 A method for preparing silver alloy powder includes the following steps: (1) Cut the silver-copper-antimony alloy ingot into small pieces, place them in the crucible of the vacuum induction melting ultrasonic atomization powder making chamber, and adjust the position of the melt nozzle at the lower end of the crucible so that it faces the ultrasonic vibrating plate. The silver-copper-antimony-yttrium alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 7.0%, Sb 0.5%; (2) Close the hatch and set the process parameters: melting temperature is 1100 ℃, melting pressure is 0.2 bar, and ultrasonic atomizer frequency is 40 kHz; (3) Evacuate the chamber until the vacuum level reaches 0.45 mbar, then fill it with high-purity argon for gas cleaning, and repeat this operation 5 times; after cleaning, adjust the chamber pressure to the melting pressure of 0.2 bar; (4) Start the program to heat and melt the silver-copper-antimony alloy ingot to obtain the alloy melt. The alloy melt drips onto the ultrasonic vibrating plate through the nozzle. Under the high-frequency vibration of the ultrasonic atomizer, it is atomized by high-pressure inert gas. The molten alloy is broken into micron-sized droplets and quickly cooled and solidified to form spherical silver-copper-antimony alloy powder. (5) Collect and wash the powder, and sieve it with a particle size range of 18μm-53μm.

[0037] After sieving, particles with a size distribution of 18μm-53μm accounted for 35% of the total mass.

[0038] Electron micrographs of the silver-copper-antimony alloy powder after sieving in this comparative example are shown below. Figure 3 As shown, this AgCuSb pre-alloyed powder exhibits significant morphological defects. The powder contains a high proportion of non-spherical particles, with numerous dumbbell-shaped, ellipsoidal, and irregularly elongated particles. During atomization, the droplets solidify before fully sphericizing, resulting in poor sphericity. Furthermore, there are obvious neck-like connections and adhesion / fusion phenomena between powder particles, indicating significant particle agglomeration.

[0039] The sphericity of the silver-copper-antimony alloy powder in this comparative example is not less than 0.81, and the Hall flow rate is 16.34 s / 50 g.

[0040] Application Example 1 A laser selective melting additive manufacturing method, characterized by comprising the following steps: Laser selective melting equipment was used to melt the Ag described in Example 1 under inert gas protection. 92.5 Cu 6.9 Sb 0.5 Y 0.1 The alloy powder is used for 3D printing to form the silver-copper-antimony-yttrium alloy powder layer by layer, thereby obtaining a silver-copper-antimony-yttrium alloy printed component.

[0041] In 3D printing, a dynamic scanning method with interlayer staggered moving heat source starting points is used for scanning. That is, between two adjacent layers, the starting point position of the laser scan is changed by translation to form staggered scanning starting points.

[0042] The main parameters of the 3D printing process include: laser power of 160W, scanning speed of 200mm / s, scanning distance of 0.04mm, and powder thickness of 0.03mm; the inert gas is high-purity argon (purity ≥99.99%), and the oxygen content in the forming chamber is controlled to be ≤300ppm and the gas pressure is kept stable at 1000Pa to prevent oxidation of powder and molten pool.

[0043] Application Example 2 A laser selective melting additive manufacturing method, characterized by comprising the following steps: Laser selective melting equipment was used to melt the Ag described in Example 2 under inert gas protection. 92.5 Cu 6.4 Sb 1.0 Y 0.1 The alloy powder is used for 3D printing to form the silver-copper-antimony-yttrium alloy powder layer by layer, thereby obtaining a silver-copper-antimony-yttrium alloy printed component.

[0044] In 3D printing, a dynamic scanning method with interlayer staggered moving heat source starting points is used for scanning. That is, between two adjacent layers, the starting point position of the laser scan is changed by translation to form staggered scanning starting points.

[0045] The main parameters of the 3D printing process include: laser power of 160W, scanning speed of 200mm / s, scanning distance of 0.04mm, and powder thickness of 0.03mm; the inert gas is high-purity argon (purity ≥99.99%), and the oxygen content in the forming chamber is controlled to be ≤300ppm and the gas pressure is kept stable at 1000Pa to prevent oxidation of powder and molten pool.

[0046] Comparative Application Example 1 A laser selective melting additive manufacturing method, characterized by comprising the following steps: Laser selective melting equipment was used to melt the Ag described in the comparative example under inert gas protection. 92.5 Cu 7.0 Sb 0.5 The alloy powder is used for 3D printing to form the silver-copper-antimony alloy powder layer by layer, thereby obtaining a silver-copper-antimony alloy printed component.

[0047] In 3D printing, a dynamic scanning method with interlayer staggered moving heat source starting points is used for scanning. That is, between two adjacent layers, the starting point position of the laser scan is changed by translation to form staggered scanning starting points.

[0048] The main parameters of the 3D printing process include: laser power of 160W, scanning speed of 200mm / s, scanning distance of 0.04mm, and powder thickness of 0.03mm; the inert gas is high-purity argon (purity ≥99.99%), and the oxygen content in the forming chamber is controlled to be ≤300ppm and the gas pressure is kept stable at 1000Pa to prevent oxidation of powder and molten pool.

[0049] Blank example 1 The silver-copper-antimony-yttrium smelting alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 6.9%, Sb 0.5%, Y 0.1%.

[0050] Blank example 2 The silver-copper-antimony smelting alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 7.0%, Sb 0.5%.

[0051] Blank example 3 The silver-copper-yttrium alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 7.4%, Y 0.1%.

[0052] Performance testing Metallographic images of the silver-copper-antimony-yttrium SLM-printed component from Application Example 1, the silver-copper-antimony SLM-printed component from Comparative Application Example 1, and the molten silver alloy ingots from Blank Examples 1-3 are shown below. Figures 4-6 As shown.

[0053] like Figure 6 As shown in (b), in the as-cast microstructure of the conventional molten AgCuSb ternary alloy of Blank Example 2, the alloy has an α-Ag solid solution as the matrix, with obvious dark network / skeleton structure at the grain boundaries, and short rod / lamellar second phases are locally visible, indicating some segregation. The number of second phases is significantly increased. These second phases can play a certain strengthening role in the alloy matrix and hinder dislocation movement, thereby significantly improving the strength of the AgCuSb alloy. However, at the same time, the continuous distribution of network / skeleton second phases can also form a continuous brittle network at the grain boundaries, which can easily induce cracks to propagate rapidly along the grain boundaries during deformation, leading to a decrease in the plasticity of the alloy. This failure path characteristic can be indirectly confirmed by metallographic observation.

[0054] like Figure 6 As shown in (c), in the as-cast microstructure of the conventional molten AgCuY ternary alloy of Blank Example 3, the alloy uses α-Ag solid solution as the matrix. Compared with the AgCuSb alloy, the grains are significantly finer, and a large number of dark-colored blocky precipitates are distributed in the matrix, resulting in a significant dispersion strengthening effect. The AgCuY alloy has no obvious grain boundary segregation, and there is no continuous brittle phase aggregation at the grain boundaries, indicating that the Y element can purify the grain boundaries. However, it can also be seen that the size of the precipitates in the AgCuY alloy is relatively large, and the uniformity of distribution is still insufficient. In addition, since no low-melting-point component was introduced, the overall solidification temperature of the alloy is still relatively high, which is not conducive to subsequent precision forming and the preparation of complex components.

[0055] like Figure 6 As shown in (a), in the as-cast microstructure of the conventional melted AgCuSbY quaternary alloy of Blank Example 1, the alloy uses α-Ag solid solution as the matrix, the grains are further refined, and the second phase is dispersed and uniform, resulting in a superimposed strengthening effect. It retains the grain refinement and dispersed precipitation characteristics brought by Y element, and improves the morphology of the second phase formed by Sb element—the continuous network / skeleton-like second phase in the original AgCuSb alloy becomes more dispersed and uniform under the action of Y element, avoiding the continuous distribution of brittle phase; at the same time, the grain boundary purification effect of Y element further improves the grain boundary bonding strength, offsetting the plasticity reduction problem brought by Sb element, and achieving a synergistic improvement in strength and plasticity. However, according to the data in Table 2, the improvement is limited.

[0056] like Figure 4 and Figure 7As shown, the microstructure of the printed component obtained from AgCuSbY alloy powder under SLM ultrafast solidification conditions exhibits significant refinement, with grain sizes much smaller than those of conventionally fused AgCuSbY alloys, and good microstructure uniformity. The matrix is ​​dominated by light-colored α-Ag solid solution, with a small amount of dark fine particles or network contrast distributed at the grain boundaries, indicating that the second phase distribution is more dispersed under the rapid solidification conditions of the SLM process, and no continuous network of hard and brittle phases is formed. This microstructure characteristic demonstrates that SLM ultrafast cooling effectively suppresses elemental segregation and the formation of continuous networks of brittle phases, thereby improving the alloy's strength and toughness while maintaining its plasticity.

[0057] like Figure 5 As shown, in the metallographic structure of the printed component obtained by SLM ultrafast solidification of AgCuSb alloy, the grain size is significantly larger than that of the AgCuSbY alloy SLM formed part, and the grains are uneven in size, without obvious uniform refinement characteristics. Obvious dark-colored dot-like defects (such as...) are visible in the microstructure. Figure 5 The black pores are unfused voids caused by poor wettability of the molten pool and spheroidization effect during the SLM process. These defects directly reduce the density and load-bearing capacity of the formed part, becoming a potential cause of early failure.

[0058] The silver-copper-antimony-yttrium SLM-printed components corresponding to Examples 1 and 2, the silver-copper-antimony SLM-printed component of Comparative Application Example 1, and the alloy ingots of Blank Examples 1-3 were subjected to Vickers hardness, tensile strength, elongation, and density tests, respectively. The test data are shown in Table 2.

[0059] The Vickers hardness measurement method is as follows: select at least 5 evenly distributed test points on the polished surface of the sample, the test force is 10 kgf (98.07 N), the holding time is 10 s, measure the diagonal length of the indentation and calculate the hardness value, and take the average value as the Vickers hardness of the sample.

[0060] The method for measuring tensile strength is as follows: the specimen is processed into a standard tensile specimen (parallel section diameter d=1.5 mm, gauge length L0=6 mm), and a uniaxial tensile test is performed at a constant strain rate of 2 mm / min under room temperature conditions. The load-displacement curve is recorded, and the tensile strength of the specimen is calculated.

[0061] Elongation is calculated by the change in gauge length before and after stretching. After the specimen breaks, the fracture surfaces are aligned, and the final length L1 of the gauge segment is measured according to the formula. Calculate the elongation, where L0 is the initial gauge length.

[0062] Density was determined using the Archimedes drainage method and tested according to the national standard GB / T 3850-2015 "Dense Sintered Metal Materials and Hard Alloys - Determination of Density".

[0063] Table 2. Mechanical Properties Tested on SLM-Printed Components and Ingots of Silver Alloy

[0064] Based on the above analysis and Table 2, with the combined addition of Sb and Y elements and the adoption of SLM technology, the silver-copper-antimony-yttrium alloy printed components exhibit a stepwise increase in strength in Application Examples 1 and 2 after SLM forming. This is due to the continuous refinement of alloy grains, the increase in the number of precipitated phases, and the more dispersed and uniform distribution, without continuous brittle network phases. The alloy microstructure is optimal, and the strength and toughness are the best. Among them, the Vickers hardness of the silver-copper-antimony-yttrium alloy SLM printed component in Application Example 1 reaches 101.96 HV, the tensile strength reaches 313.44 MPa, the elongation is as high as 41%, and the density is as high as 98.7%, all of which are significantly higher than the silver-copper-antimony alloy SLM printed component with only Sb element added, and far higher than the original molten state AgCuSbY alloy ingot, AgCuSb alloy ingot, and AgCuY alloy ingot without SLM printing.

[0065] This is likely due to the low sphericity and poor flowability of AgCuSb alloy powder, which leads to elemental segregation and poor wettability in SLM-printed components, severely affecting their density, uniformity, and mechanical properties. In contrast, the high sphericity and good flowability of AgCuSbY alloy powder can significantly improve the uniformity of SLM powder spreading, thereby obtaining AgCuSbY printed components with high density and high uniformity.

[0066] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A silver alloy powder, characterized in that, The silver-copper-antimony-yttrium alloy powder is formed from raw materials comprising, by mass percentage: Ag 92.5%, Cu 6%-6.9%, Sb 0.5%-1%, and Y 0.1%-0.5%.

2. The silver alloy powder according to claim 1, characterized in that, The mass ratio of Sb to Y is Sb:Y = (2-10):1, preferably Sb:Y = 5:

1.

3. The silver alloy powder according to claim 1, characterized in that, The sphericity of the silver-copper-antimony-yttrium alloy powder is not less than 0.967, wherein the particle size distribution of 38µm-53µm accounts for more than 55% of the total mass.

4. A method for preparing silver alloy powder, characterized in that, The method for preparing the silver alloy powder according to any one of claims 1-3 includes the following steps: using a vacuum induction gas atomization powder preparation device, with an inert gas as the medium, melting and gas atomizing silver-copper-antimony-yttrium alloy ingots to obtain spherical silver-copper-antimony-yttrium alloy powder. The silver-copper-antimony-yttrium alloy ingot is composed of the following components by mass percentage: Ag 92.5%, Cu 6%-6.9%, Sb 0.5%-1%, Y 0.1%-0.5%.

5. The preparation method according to claim 4, characterized in that, The melting temperature is 1000℃-1200℃; the melting pressure is 0.2 bar-0.3 bar; and the ultrasonic atomizer vibration frequency is 35 kHz-45 kHz.

6. The preparation method according to claim 4, characterized in that, It also includes the step of sieving the silver-copper-antimony-yttrium alloy powder according to a particle size range of 18μm-53μm.

7. A laser selective melting additive manufacturing method, characterized in that, Includes the following steps: Using a laser selective melting device under inert gas protection, 3D printing is performed using the silver-copper-antimony-yttrium alloy powder described in any one of claims 1-3 as raw material, so that the silver-copper-antimony-yttrium alloy powder is formed layer by layer to obtain a silver-copper-antimony-yttrium alloy printed component; In particular, a dynamic scanning method with interlayer staggered moving heat source starting points is used for scanning during 3D printing.

8. The additive manufacturing method according to claim 7, characterized in that, The dynamic scanning method of interlayer staggered moving heat source starting point refers to changing the position of the laser scanning starting point between two or more adjacent layers during 3D printing by translation or rotation, so as to form staggered scanning starting points.

9. The additive manufacturing method according to claim 7, characterized in that, The settings parameters of the laser selective melting equipment include: laser power of 150W-450W, scanning speed of 200mm / s-1600mm / s, scanning spacing of 0.03mm-0.10mm, and powder thickness of 0.02mm-0.04mm.

10. A silver alloy part, characterized in that, The silver-copper-antimony-yttrium alloy part is obtained by the laser selective melting additive manufacturing method as described in any one of claims 7-9; The silver-copper-antimony-yttrium alloy parts have a density of at least 98.5%, a hardness of at least 98.47 HV, a tensile strength of at least 313.44 MPa, and an elongation of at least 34%.

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