Medium-entropy alloy powder, heterogeneous high-strength VCoNi system medium-entropy alloy and preparation method and application of heterogeneous high-strength VCoNi system medium-entropy alloy

Abstract

The invention relates to medium-entropy alloy powder, a heterogeneous high-strength VCoNi series medium-entropy alloy and a preparation method and application of the medium-entropy alloy, belongs to the field of laser processing materials, and solves at least one of the problems that in the prior art, the strength, plasticity and toughness of the entropy alloy are difficult to synergistically improve in the laser additive manufacturing process, and cracks and air hole defects occur. The entropy alloy powder in the VCoNi system comprises the following chemical components: 29.5%-30.5% of V, 37.5%-39.0% of Co, 26.5%-28.0% of Ni, 3.8%-4.9% of Al, 0.003%-0.03% of C, less than or equal to 5ppm of H, less than or equal to 100ppm of N and less than or equal to 200ppm of O. The powder provided by the invention synergistically realizes improvement of the strength, plasticity and toughness of the alloy, and the preparation method realizes improvement of the strength, plasticity and toughness of the medium-entropy alloy.

Description

Technical Field

[0001] This invention relates to the field of laser processing materials technology, and in particular to a medium-entropy alloy powder, a multiphase heterogeneous high-strength VCoNi medium-entropy alloy, its preparation method and application. Background Technology

[0002] With the development of aerospace technology, nickel-based superalloy components for aerospace applications are showing a trend towards greater complexity, thinner walls, composite materials, and integration. Their structural materials must balance high strength, high plasticity, and high toughness. Medium-entropy alloys, with their superior mechanical properties of high strength, high plasticity, and high toughness, can ensure the safety and service life of alloy components. Furthermore, the high strength of medium-entropy alloys enables lightweighting, meeting the stringent requirements of engineering applications, making them a metallic material with enormous development potential.

[0003] At present, the preparation of medium entropy alloys mostly adopts the traditional casting and forging process. The traditional casting and forging process will result in serious compositional segregation and difficulty in controlling the grain size. In the preparation of complex structure workpieces, the traditional casting and forging process often requires multiple complex processes, and the one-time forming rate is low and the economic cost is high.

[0004] Laser additive manufacturing technology can achieve one-step forming of medium-entropy alloy parts. Appropriate laser additive manufacturing parameters can improve compositional segregation and formability, significantly reducing economic and time costs for some complex workpieces. However, the laser additive manufacturing of medium-entropy alloys currently faces three major technical bottlenecks: First, high crack sensitivity; the enormous thermal stress generated by rapid melting and solidification, coupled with the segregation of brittle phases at grain boundaries in complex compositional systems, easily induces internal cracks. Second, difficulty in balancing strength and plasticity; the microstructure after printing often fails to achieve the ideal ratio of reinforcing phases and plastic matrix, leading to a significant decrease in plasticity while increasing strength. Third, difficulty in precisely controlling the process and microstructure; the relationship between process parameters, powder characteristics, and final microstructure properties is complex, and defects are easily generated within a narrow process window, making it difficult to stably reproduce high-performance multiphase microstructures. Therefore, to address these issues, there is an urgent need to develop a novel medium-entropy alloy and manufacturing method that synergistically optimizes composition and process. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a medium-entropy alloy powder, a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy, its preparation method and application, in order to solve at least one of the problems in the existing medium-entropy alloys during laser additive manufacturing, such as the difficulty in synergistically improving alloy strength, plasticity and toughness, and the occurrence of cracks and porosity defects.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a VCoNi-based medium-entropy alloy powder for additive manufacturing. The chemical composition of the VCoNi-based medium-entropy alloy powder, by mass percentage, includes: V: 29.5%–30.5%, Co: 37.5%–39.0%, Ni: 26.5%–28.0%, Al: 3.8%–4.9%, C: 0.003%–0.03%, H: ≤5ppm, N: ≤100ppm, O: ≤200ppm.

[0008] Furthermore, the VCoNi-based entropy alloy powder satisfies at least one of the following characteristics:

[0009] (1) The particle size range is 53μm~120μm;

[0010] (2) Sphericity ≥ 90%;

[0011] (3) Flowability ≤15g / 50s;

[0012] (4) Hollow powder ratio ≤ 0.1%.

[0013] This invention provides a method for preparing multiphase heterogeneous high-strength VCoNi-based medium-entropy alloys, comprising the following steps:

[0014] (1) Provide VCoNi-based medium-entropy alloy powder, wherein the chemical composition of the VCoNi-based medium-entropy alloy powder comprises, by mass percentage: V: 29.5%–30.5%, Co: 37.5%–39.0%, Ni: 26.5%–28.0%, Al: 3.8%–4.9%, C: 0.003%–0.03%, H: ≤5ppm, N: ≤100ppm, O: ≤200ppm;

[0015] Using the VCoNi-based medium-entropy alloy powder, an additive manufacturing blank is obtained by layer-by-layer forming through laser melting deposition process;

[0016] (2) The additively manufactured preform is subjected to two heat treatments in sequence:

[0017] Step 1: Perform heat treatment at 1100℃~1200℃;

[0018] Step 2: Heat treatment at 800℃~850℃.

[0019] Furthermore, the holding time of the first heat treatment in step (2) is 24h to 48h, and water quenching is used after the heat treatment; the holding time of the second heat treatment is 1h to 2h, and water quenching is used after the heat treatment.

[0020] Furthermore, the parameters used in the laser melting deposition process include: laser power of 1600W to 2600W, scanning speed of 0.36m / min to 0.60m / min, and powder feeding speed of 4g / min to 8g / min; and / or,

[0021] The overlap rate is 40% to 50%.

[0022] Furthermore, in the laser melting deposition process, a forming path strategy of single-layer serpentine reciprocating scanning and interlayer rotation of 60-120° is adopted.

[0023] This invention provides a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy, which is prepared using the aforementioned method.

[0024] Furthermore, the microstructure of the multiphase heterogeneous high-strength VCoNi medium-entropy alloy includes a face-centered cubic (FCC) matrix phase and an L... 12 The phases are BCC phase and σ phase, with the BCC phase comprising 5% to 7% by volume, and the L phase comprising... 12 The content of the phase is 16% to 18%, and the content of the σ phase is 1% to 2%.

[0025] Furthermore, the room temperature mechanical properties of the multiphase heterogeneous high-strength VCoNi medium-entropy alloy meet the following requirements: tensile strength ≥1800MPa, yield strength ≥1500MPa, and elongation after fracture ≥25%.

[0026] This invention provides the application of multiphase heterogeneous high-strength VCoNi-based medium-entropy alloys prepared according to the preparation method, or the multiphase heterogeneous high-strength VCoNi-based medium-entropy alloys, in the fields of aerospace, high-strength structural components, or complex integrated component manufacturing.

[0027] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0028] (1) The VCoNi-based medium-entropy alloy powder provided by this invention constructs an ideal multiphase heterogeneous strengthening structure by designing a specific composition of the VCoNi-Al medium-entropy alloy with non-equiatomic ratios. Specifically, in the alloy system of this invention, the content of Co element is significantly higher than that of Ni and V elements. By increasing the Co element content (37.5% to 39.0%), the key intermetallic compound L is promoted. 12The precipitation of the strengthening phase (chemical formula AlCo2V) is achieved; by setting an appropriate Ni content (26.5%–28.0%), the face-centered cubic (FCC) matrix phase can be stabilized, thereby ensuring that the alloy has the necessary plastic deformation capacity and toughness reserve; by controlling the content of V and Al, the proportion of V is appropriately reduced to effectively suppress the excessive formation of the brittle σ phase, while the addition of a specific amount of Al (3.8%–4.9%) will guide the formation of the body-centered cubic (BCC) hard phase.

[0029] Through the synergistic effect of the above components, the alloy, after forming, obtains a structure consisting of an FCC plastic matrix, a BCC hard phase, and L... 12 A multiphase heterogeneous microstructure is formed by a nano-reinforced phase and a controlled amount of σ phase. This structure ingeniously combines the mechanical properties of each phase, ensuring high elongation with the FCC phase, and further enhancing the properties through the BCC and L phases. 12 Multiple mechanisms, such as coherent strengthening of the phase and precipitation strengthening of the σ phase, work together to achieve a comprehensive and significant improvement in the alloy's strength, plasticity, and toughness.

[0030] (2) Based on the VCoNi-based medium-entropy alloy powder, this invention provides a matching laser additive manufacturing method. Specifically, the VCoNi-based medium-entropy alloy powder, designed based on non-equiatomic main elements and with strict control over interstitial elements C and impurity elements, has laid the foundation for the composition and phase composition of high-strength and tough alloy systems. Furthermore, this invention provides a synergistic process of "laser melting deposition - two-step heat treatment": by combining the rapid near-net-shape forming capability of additive manufacturing with the precise phase transformation control capability of heat treatment, it achieves the control of FCC matrix, BCC phase, and L... 12 The optimization of the proportion, distribution, and morphology of the four-phase microstructure, including the L phase and σ phase, is achieved. This process not only fully utilizes the pre-defined L phase parameters in the composition design, but also optimizes the proportion, distribution, and morphology of the four-phase microstructure. 12 The phase enhances the potential of BCC phase, and can also fully eliminate manufacturing internal stress and promote uniform element diffusion through the first high-temperature treatment (1100℃~1200℃), and finely control L through the second medium-temperature treatment (800℃~850℃). 12 The dispersed precipitation of the phase and the controlled distribution of the σ phase, as well as the formation of the BCC phase. Ultimately, while retaining the excellent plasticity of the FCC matrix, the L phase is comprehensively utilized. 12 The coherent strengthening of the BCC phase and the precipitation strengthening effect of a small amount of σ phase result in a significant comprehensive improvement in the strength, plasticity and toughness of the medium-entropy alloy, making it suitable for the integrated near-net-shape forming of complex structures.

[0031] (3) Based on the VCoNi system medium-entropy alloy powder, this invention employs laser melting deposition technology combined with a two-step heat treatment process to achieve high-quality and high-efficiency preparation of complex structures, overcoming the limitations of traditional casting and rolling processes. After forming, this invention eliminates the need for multi-step deformation and recrystallization processes, resulting in higher forming efficiency and significant time and cost savings.

[0032] (4) In some preferred embodiments, the stability and forming quality of the laser additive manufacturing process are ensured by controlling the powder particle size, sphericity, flowability, and hollow powder ratio. A suitable particle size distribution facilitates uniform powder spreading and layer thickness control; high sphericity ensures good flowability and packing density; optimized flowability ensures continuous and stable powder feeding; and an extremely low hollow powder ratio reduces internal defects in the formed parts from the source. The synergistic control of these physical properties provides better assurance for improving the density, surface quality, and mechanical property consistency of the formed parts.

[0033] (5) In some preferred embodiments, precise phase composition control and performance optimization can be achieved by limiting the holding time and cooling method in the two-step heat treatment. The long holding time (24-48 hours) of the first heat treatment ensures sufficient diffusion of alloying elements, eliminates microsegregation, and promotes composition homogenization; the medium holding time (1-2 hours) of the second heat treatment precisely controls L 12 The precipitation behavior of the σ phase and the BCC phase. Water quenching, as a rapid cooling method, can effectively fix the phase composition obtained by heat treatment, prevent unfavorable phase transformations during cooling, and further strengthen the material through the microstructure refinement effect produced by rapid cooling. This synergistic effect of the heat treatment regime enables the alloy to achieve increased strength while maintaining good plasticity.

[0034] (6) In some preferred embodiments, by controlling key parameters such as laser power, scanning speed, powder feeding speed, and overlap rate within a specific range, precise control of the molten pool morphology and heat input can be achieved, ensuring consistent forming quality. Appropriate laser power (1600-2600W) ensures sufficient powder melting while avoiding excessive evaporation; optimized matching of scanning speed (0.36-0.60m / min) and powder feeding speed (4-8g / min) ensures a uniform and continuous melt path; and an overlap rate of 40%-50% ensures sufficient metallurgical bonding between layers. The synergistic control of these parameters helps reduce defects such as porosity and lack of fusion, improving the density and mechanical property stability of the formed parts.

[0035] (7) In some preferred embodiments, a path strategy employing a single-layer serpentine reciprocating scan with interlayer rotation at a specific angle can effectively control the heat accumulation distribution and improve the anisotropy of the formed part. This strategy disrupts the heat flow transfer path by changing the scanning direction of each layer, avoiding deformation, warping, and cracking tendencies caused by unidirectional heat accumulation. At the same time, interlayer rotation helps promote grain growth in different directions, refines the microstructure, and improves the uniformity of mechanical properties, which is particularly beneficial for optimizing the overall performance of complex structural parts.

[0036] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0037] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0038] Figure 1 This is a SEM image of the morphology of VCoNi-based medium-entropy alloy powder provided in an embodiment of the present invention;

[0039] Figure 2 The image shows the XRD results of the VCoNi-based medium-entropy alloy obtained by the preparation method described in the embodiments of the present invention.

[0040] Figure 3 This is a SEM image showing the microstructure of the VCoNi-based entropy alloy obtained by the preparation method described in this embodiment of the invention. Detailed Implementation

[0041] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0042] In a first aspect, the present invention provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, wherein the chemical composition of the VCoNi-based medium-entropy alloy powder comprises, by mass percentage: V: 29.5%–30.5%, Co: 37.5%–39.0%, Ni: 26.5%–28.0%, Al: 3.8%–4.9%, C: 0.003%–0.03%, H: ≤5ppm, N: ≤100ppm, O: ≤200ppm.

[0043] For example, in addition to the above-mentioned components, the balance is unavoidable impurities.

[0044] Compared with existing technologies, the VCoNi-based medium-entropy alloy powder provided by this invention constructs an ideal multiphase heterogeneous strengthening microstructure through specific compositional design of the VCoNi-Al medium-entropy alloy with non-equiatomic ratios. Specifically, in the alloy system of this invention, the Co element content is significantly higher than that of Ni and V elements; by increasing the Co element content (37.5%–39.0%), the key intermetallic compound L is promoted. 12 The precipitation of the strengthening phase (chemical formula AlCo2V) is achieved; by setting an appropriate Ni content (26.5%–28.0%), the face-centered cubic (FCC) matrix phase can be stabilized, thereby ensuring that the alloy has the necessary plastic deformation capacity and toughness reserve; by controlling the content of V and Al, the proportion of V is appropriately reduced to effectively suppress the excessive formation of the brittle σ phase, while the addition of a specific amount of Al (3.8%–4.9%) will guide the formation of the body-centered cubic (BCC) hard phase.

[0045] Through the synergistic effect of the above components, the alloy, after forming, obtains a structure consisting of an FCC plastic matrix, a BCC hard phase, and L... 12 A multiphase heterogeneous microstructure is formed by a nano-reinforced phase and a controlled amount of σ phase. This structure ingeniously combines the mechanical properties of each phase, ensuring high elongation with the FCC phase, and through L... 12 Multiple mechanisms, including the coherent strengthening of the BCC phase and the precipitation strengthening of the σ phase, synergistically achieve a significant comprehensive improvement in the alloy's strength, hardness, plasticity, and toughness.

[0046] Specifically, the design principles and mechanisms of action of each element in the VCoNi-based entropy alloy powder are as follows:

[0047] I. Collaborative Design of Primary Elements

[0048] Cobalt (Co): As the most abundant element, its main role is to promote the formation of intermetallic compounds, such as L... 12 Precipitation of the strengthening phase (AlCo2V). L 12 The phase is coherent with the FCC matrix and can effectively hinder dislocation movement, making it a key reinforcing phase for achieving high strength and high toughness.

[0049] Nickel (Ni): Its main function is to stabilize the face-centered cubic (FCC) matrix phase, ensuring that the alloy has good plastic deformation capacity and toughness reserve, which is the guarantee of high elongation.

[0050] Vanadium (V): Its content was appropriately reduced, with the main purpose of effectively suppressing the formation of excessive brittle σ phase. Although σ phase can also strengthen, excessive amounts will seriously impair plasticity.

[0051] Aluminum (Al): Its addition induces the formation of the body-centered cubic (BCC) phase. The BCC phase, as a hard phase, combines with the tough FCC phase to form a strong and tough coherent dual-phase microstructure with a "hard-soft" bond, synergistically enhancing strength and toughness. Simultaneously, Al is a key component in the formation of L... 12 Essential building blocks of a phase.

[0052] II. Precise control of key trace element C

[0053] Carbon (C): In this invention, the carbon content in the alloy powder is strictly controlled within an extremely low range of 0.003% to 0.03%. After laser additive manufacturing and subsequent heat treatment, the volume fraction of the brittle σ phase in the obtained alloy bulk is limited to a low level of 1% to 2%. This σ phase is incoherent with the matrix face-centered cubic (FCC) phase and can strongly hinder dislocation movement, thereby effectively contributing to precipitation strengthening. By maintaining the carbon content at a low level, this invention enables the σ phase to significantly improve the strength without excessively impairing the alloy's plasticity, achieving a good synergy between strength and plasticity.

[0054] III. Strict control of impurity elements

[0055] Regarding the control of oxygen (O) content and its beneficial effects: In laser additive manufacturing, low oxygen content in powder helps reduce the formation of oxide inclusions, thereby reducing the risk of crack initiation and improving the density, strength, and plasticity of the alloy. Simultaneously, low oxygen content helps maintain the homogeneity of the FCC matrix structure, optimizes deformation mechanisms such as dislocation slip, and promotes the formation of a denser oxide film on the alloy surface, effectively inhibiting the intrusion of corrosive media, improving the alloy's corrosion resistance, and extending its service life.

[0056] Regarding the control and necessity of nitrogen (N) content: This invention controls the nitrogen content at a low level. This is because, in the laser additive manufacturing process, if the nitrogen content is too high, the nitrogen dissolved in the molten pool at high temperatures is prone to precipitate and form pores during rapid cooling, reducing density; more seriously, excessive nitrogen may cause nitrogen embrittlement, significantly weakening the ultimate tensile strength and toughness of the formed component. Low nitrogen content can reduce such defects and performance risks from the source.

[0057] Strict control of hydrogen (H) content is required. This invention mandates that the hydrogen content in the alloy powder not exceed 5 ppm. Excessive hydrogen content is highly likely to remain during the solidification process of the molten pool, potentially leading to porosity, reduced density, and hydrogen embrittlement, which poses a risk of sudden fracture under stress in the formed component. Controlling the hydrogen content to extremely low levels effectively reduces porosity, increases density, and significantly extends the fatigue life of the component.

[0058] In summary, this invention, through the design of main element compositions with non-equiatomic ratios, actively constructs a phase composed of FCC, BCC, and L phases in VCoNi-Al alloys. 12 The multiphase heterogeneous strengthening structure composed of the phase and the controlled σ phase comprehensively improves the strength and plasticity of the alloy. At the same time, through the extreme synergistic control of carbon (C) and impurity elements such as oxygen (O), nitrogen (N), and hydrogen (H), the microstructure and defect state of the component in the laser additive manufacturing process are optimized from the powder source, thereby significantly improving the strength, toughness, corrosion resistance and fatigue life of the material while ensuring good plasticity.

[0059] For example, the Co content in the VCoNi-based medium entropy alloy powder is 37.5%, 37.6%, 37.7%, 37.8%, 37.9%, 38.0%, 38.1%, 38.2%, 38.3%, 38.4%, 38.5%, 38.6%, 38.7%, 38.8%, 38.9%, or 39.0%; preferably 38.2% to 38.8%.

[0060] For example, the Ni content in the VCoNi-based medium entropy alloy powder is 26.5%, 26.6%, 26.7%, 26.8%, 26.9%, 27.0%, 27.1%, 27.2%, 27.3%, 27.4%, 27.5%, 27.6%, 27.7%, 27.8%, 27.9%, or 28.0%; preferably 26.7% to 27.5%.

[0061] For example, in the VCoNi-based medium entropy alloy powder, the V content is 29.5%, 29.6%, 29.7%, 29.8%, 29.9%, 30.0%, 30.1%, 30.2%, 30.3%, 30.4%, or 30.5%; preferably 29.5% to 30.0%.

[0062] For example, the Al content in the VCoNi-based medium entropy alloy powder is 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, or 4.9%; preferably 4.1% to 4.6%.

[0063] For example, the C content in the VCoNi-based medium entropy alloy powder is 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.015%, 0.02%, 0.025%, or 0.03%; preferably 0.003% to 0.01%.

[0064] Preferably, in the VCoNi-based medium-entropy alloy powder, H: ≤5ppm, N: ≤100ppm, O: ≤150ppm.

[0065] Specifically, the VCoNi-based entropy alloy powder satisfies at least one of the following characteristics:

[0066] (1) The particle size range is 53μm~120μm;

[0067] (2) Sphericity ≥ 90%;

[0068] (3) Flowability ≤15g / 50s;

[0069] (4) Hollow powder ratio ≤ 0.1%.

[0070] Preferably, the VCoNi-based medium entropy alloy powder simultaneously meets the above conditions (1) to (4): the particle size range is 53μm to 120μm, the sphericity is ≥90%, the flowability is ≤15g / 50s, and the hollow powder rate is ≤0.1%.

[0071] For example, the particle size of the VCoNi-based medium entropy alloy powder is 53μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, or 120μm; preferably, the particle size range of the VCoNi-based medium entropy alloy powder is 70μm to 100μm.

[0072] Preferably, the sphericity of the VCoNi-based medium entropy alloy powder is ≥95%.

[0073] Preferably, the flowability of the VCoNi-based medium entropy alloy powder is ≤14.5g / 50s.

[0074] Preferably, the hollow powder ratio of the VCoNi-based entropy alloy powder is ≤0.05%.

[0075] Specifically, the loose packing density of the VCoNi-based entropy alloy powder is 3.80 g / cm³. 3 ~4.18g / cm 3 The tap density is 4.56 g / cm³. 3 ~4.94g / cm 3 .

[0076] Specifically, the VCoNi-based medium-entropy alloy powder of the present invention is prepared using plasma rotating electrode atomization powder preparation technology.

[0077] Secondly, the present invention provides a method for preparing multiphase heterogeneous high-strength VCoNi-based medium-entropy alloys, comprising the following steps:

[0078] (1) Provide VCoNi-based medium-entropy alloy powder, wherein the chemical composition of the VCoNi-based medium-entropy alloy powder comprises, by mass percentage: V: 29.5%–30.5%, Co: 37.5%–39.0%, Ni: 26.5%–28.0%, Al: 3.8%–4.9%, C: 0.003%–0.03%, H: ≤5ppm, N: ≤100ppm, O: ≤200ppm;

[0079] Using the VCoNi-based medium-entropy alloy powder, an additive manufacturing blank is obtained by layer-by-layer forming through laser melting deposition process;

[0080] (2) The additively manufactured preform is subjected to two heat treatments in sequence:

[0081] Step 1: Perform heat treatment at 1100℃~1200℃;

[0082] Step 2: Heat treatment at 800℃~850℃.

[0083] Compared with existing technologies, this invention provides a laser additive manufacturing method based on the aforementioned VCoNi-based medium-entropy alloy powder. Specifically, the VCoNi-based medium-entropy alloy powder, designed based on non-equiatomic main elements and with strict control over interstitial elements C and impurity elements, has laid the foundation for the composition and phase composition of high-strength and tough alloy systems. Furthermore, this invention provides a synergistic process of "laser melting deposition - two-step heat treatment": by combining the rapid near-net-shape forming capability of additive manufacturing with the precise phase transformation control capability of heat treatment, it achieves precise control over the FCC matrix, BCC phase, and L... 12 The optimization of the proportion, distribution, and morphology of the four-phase microstructure, including the L phase and σ phase, is achieved. This process not only fully utilizes the pre-defined L phase parameters in the composition design, but also optimizes the proportion, distribution, and morphology of the four-phase microstructure. 12 The phase enhances the potential of BCC phase, and can also fully eliminate manufacturing internal stress and promote uniform element diffusion through the first high-temperature treatment (1100℃~1200℃), and finely control L through the second medium-temperature treatment (800℃~850℃). 12 The dispersed precipitation of the phase and the controlled distribution of the σ phase. Ultimately, while retaining the excellent plasticity of the FCC matrix, the L phase is comprehensively utilized. 12 The coherent strengthening of the BCC phase and the precipitation strengthening effect of a small amount of σ phase result in a significant comprehensive improvement in the strength, plasticity and toughness of the medium-entropy alloy, making it suitable for the integrated near-net-shape forming of complex structures.

[0084] Specifically, the holding time of the first heat treatment in step (2) is 24h to 48h, and water quenching is used after the first heat treatment; the holding time of the second heat treatment is 1h to 2h, and water quenching is used after the second heat treatment.

[0085] For example, the temperature of the first heat treatment is 1100℃, 1120℃, 1140℃, 1145℃, 1150℃, 1155℃, 1160℃, 1180℃, or 1200℃; and the holding time of the first heat treatment is 24h, 28h, 32h, 36h, 40h, 44h, or 48h.

[0086] Preferably, the temperature of the first heat treatment is 1140℃~1160℃, and the holding time is 36h~48h.

[0087] For example, the temperature of the second heat treatment step is 800℃, 810℃, 820℃, 825℃, 830℃, 835℃, 840℃, or 850℃; the holding time of the second heat treatment step is 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.8h, or 2.0h.

[0088] Preferably, the temperature of the second heat treatment step is 820℃~840℃, and the holding time is 1h~1.5h.

[0089] Preferably, the temperature is increased from room temperature to the temperature of the first heat treatment at a rate of 5℃ / min to 10℃ / min; after the first heat treatment is completed, the temperature is increased from room temperature to the temperature of the second heat treatment at a rate of 5℃ / min to 10℃ / min.

[0090] Specifically, air is used in the two-step heat treatment process.

[0091] Specifically, the parameters used in the laser melting deposition process include: laser power of 1600W to 2600W, scanning speed of 0.36m / min to 0.60m / min, and powder feeding speed of 4g / min to 8g / min.

[0092] Specifically, the parameters used in the laser melting deposition process also include: an overlap rate of 40% to 50% and a spot diameter of 2 mm to 5 mm.

[0093] For example, during the laser melting deposition process, the laser power is 1600W, 1800W, 2000W, 2200W, 2400W, and 2600W; the spot diameter is 2mm, 3mm, 4mm, and 5mm; the scanning speed is 0.36m / min, 0.38m / min, 0.40m / min, 0.45m / min, 0.50m / min, 0.55m / min, and 0.60m / min; and the powder feeding speed is 4g / min, 5g / min, 6g / min, 7g / min, and 8g / min. The overlap rate is 40%, 42%, 44%, 45%, 46%, 48%, and 50%.

[0094] Preferably, the parameters used in the laser melting deposition process include: laser power of 1600–2200 W; scanning speed of 0.42–0.54 m / min; powder feeding speed of 5–7 g / min; and overlap rate of 45%–50%.

[0095] It should be noted that the laser power setting must be matched with the scanning speed and powder feeding rate. When the laser power is too high, excessive energy input will cause the molten pool to overheat, resulting in powder splashing, surface roughening of the formed part, and may induce thermal stress cracks and grain coarsening, thereby deteriorating mechanical properties. When the laser power is too low, insufficient energy will prevent the powder from melting completely, leading to incomplete fusion defects, void formation, and weakened interlayer bonding, significantly reducing the density and structural integrity of the formed part.

[0096] Specifically, in the laser melting deposition process, a forming path strategy of single-layer serpentine reciprocating scanning with interlayer rotation of 60–120° is adopted. Using a single-layer serpentine reciprocating scanning path and rotating the layers at appropriate angles for layer-by-layer printing can disperse thermal stress and refine grains, effectively suppressing crack formation and improving microstructure uniformity.

[0097] For example, the interlayer rotation is 60°, 70°, 80°, 90°, 100°, 110°, or 120°; preferably 85° to 95°.

[0098] Specifically, the VCoNi-based medium-entropy alloy powder is dried before laser melting deposition. For example, the VCoNi-based medium-entropy alloy powder is placed in a vacuum drying oven and dried at 80–120°C (e.g., 90°C, 100°C, 110°C) for 2–4 hours (2.5 hours, 3.0 hours, 3.5 hours).

[0099] Thirdly, the present invention provides a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy, which is prepared by the preparation method described in the second aspect.

[0100] Specifically, the microstructure of the multiphase heterogeneous high-strength VCoNi medium-entropy alloy includes a face-centered cubic (FCC) matrix phase and an L... 12 The phases are BCC phase and σ phase, with the BCC phase comprising 5% to 7% by volume, and the L phase comprising... 12 The content of the phase is 16% to 18%, and the content of the σ phase is 1% to 2%.

[0101] It should be noted that the FCC phase can improve the plasticity of the alloy, and a small amount of σ phase (1%–2%) can play a certain strengthening role. L phase dissolved in the FCC phase… 12The phase (16%–18%) hinders dislocations, thus playing a strengthening role. The BCC phase (5%–7%) is a hard phase, which, together with the FCC phase, can form a strong and tough coherent dual-phase microstructure, thereby significantly improving the mechanical properties of VCoNi-based medium entropy alloys.

[0102] The VCoNi medium-entropy alloy obtained by the preparation method of the present invention has excellent mechanical properties; specifically, the room temperature mechanical properties of the multiphase heterogeneous high-strength VCoNi medium-entropy alloy meet the following requirements: tensile strength ≥1800MPa, yield strength ≥1500MPa, and elongation after fracture ≥25%.

[0103] Fourthly, the present invention provides the application of multiphase heterogeneous high-strength VCoNi-based medium-entropy alloys prepared according to the preparation method described in the second aspect or the multiphase heterogeneous high-strength VCoNi-based medium-entropy alloys described in the third aspect in the fields of aerospace, high-strength structural components or complex integrated components manufacturing.

[0104] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0105] Example 1:

[0106] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing. Its chemical composition, by mass percentage, is: V: 30.5%, Co: 37.5%, Ni: 28.0%, Al: 3.8%, C: 0.03%, H: 5ppm, N: 100ppm, O: 200ppm, with the balance being unavoidable impurities. The VCoNi-based medium-entropy alloy powder (e.g....) Figure 1 The powder was prepared using plasma rotating electrode atomization technology, with a particle size range of 53μm to 120μm, a sphericity of 96%, a flowability of 13g / 50s, a hollow powder ratio of 0.03%, and a bulk density of 3.80g / cm³. 3 The tap density is 4.60 g / cm³. 3 .

[0107] This embodiment provides a method for preparing multiphase heterogeneous high-strength VCoNi-based medium-entropy alloys, the specific steps of which are as follows:

[0108] (1) The VCoNi medium entropy alloy powder was placed in a vacuum drying oven and dried at 100°C for 3 hours.

[0109] (2) The dried powder is used to form an additive manufacturing blank layer by layer through laser melting deposition process; the parameters of the laser melting deposition process are: laser power 2000W, spot diameter 3mm, scanning speed 0.48m / min, powder feeding speed 6g / min, overlap rate 45%; the forming path adopts single-layer serpentine reciprocating scanning with 90° rotation between layers.

[0110] (3) The additively manufactured preform is subjected to two heat treatments in an air atmosphere:

[0111] Step 1: Heat the sample from room temperature to 1150℃ at a rate of 8℃ / min and hold for 36 hours, then cool it with water.

[0112] Step 2: Heat from room temperature to 830℃ at a rate of 8℃ / min and hold for 1.5 hours, then cool by water quenching.

[0113] Example 2

[0114] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing. Its chemical composition, by mass percentage, is: V: 29.5%, Co: 39.0%, Ni: 26.5%, Al: 4.9%, C: 0.003%, H: 3ppm, N: 80ppm, O: 180ppm, with the balance being unavoidable impurities. The VCoNi-based medium-entropy alloy powder is prepared using plasma rotating electrode atomization powder preparation technology. The particle size range is 53μm–120μm, the sphericity is 94%, the flowability is 12g / 50s, the hollow powder ratio is 0.03%, and the bulk density is 4.15g / cm³. 3 The tap density is 4.84 g / cm³. 3 .

[0115] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The steps and parameters are the same as in Example 1, except that the VCoNi medium-entropy alloy powder used in this embodiment is different.

[0116] Example 3

[0117] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing. Its chemical composition, by mass percentage, is: V: 29.9%, Co: 38.3%, Ni: 27.3%, Al: 4.4%, C: 0.003%, H: 3ppm, N: 75ppm, O: 73ppm, with the balance being unavoidable impurities. The VCoNi-based medium-entropy alloy powder is prepared using plasma rotating electrode atomization powder preparation technology. The particle size range is 53μm–100μm, the sphericity is 94%, the flowability is 13g / 50s, the hollow powder ratio is 0.03%, and the bulk density is 3.95g / cm³.3 The tap density is 4.72 g / cm³. 3 .

[0118] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The steps and parameters are the same as in Example 1, except that the VCoNi medium-entropy alloy powder used in this embodiment is different.

[0119] Example 4

[0120] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0121] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition and laser melting deposition process steps and parameters are the same as in Embodiment 3. The difference lies in the two heat treatment parameters. In this embodiment, the first step is to hold at 1100℃ for 48 hours, followed by water quenching and cooling; the second step is to hold at 850℃ for 1 hour, followed by water quenching and cooling.

[0122] Example 5

[0123] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0124] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition and laser melting deposition process steps and parameters are the same as in Embodiment 3. The difference lies in the two heat treatment parameters. In this embodiment, the first step is to hold at 1200℃ for 24 hours, followed by water quenching and cooling; the second step is to hold at 800℃ for 2 hours, followed by water quenching and cooling.

[0125] Example 6

[0126] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0127] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy, the difference being the heating rate of the two-step heat treatment; in this embodiment, the temperature is raised from room temperature to 1150℃ at a rate of 12℃ / min, held for 36h and then air-cooled to room temperature; the temperature is raised to 830℃ at a rate of 12℃ / min, held for 1.5h and then air-cooled to room temperature.

[0128] Example 7

[0129] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0130] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition, heat treatment process steps and parameters are the same as those in Example 3. The difference lies in the laser melting deposition parameters. In this embodiment, the laser power is 2600W, the scanning speed is 0.36m / min, the powder feeding speed is 4g / min, the overlap rate is 50%, and the interlayer rotation is 80°.

[0131] Example 8

[0132] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0133] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition, heat treatment process steps and parameters are the same as those in Example 3. The difference lies in the laser melting deposition parameters. In this embodiment, the laser power is 1600W, the scanning speed is 0.60m / min, the powder feeding speed is 8g / min, the overlap rate is 40%, and the interlayer rotation is 100°.

[0134] Example 9

[0135] This embodiment provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0136] This embodiment provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition, heat treatment process steps and parameters are the same as those in Example 3. The difference lies in the laser melting deposition parameters. In this embodiment, the laser power is 2600W, the scanning speed is 0.30m / min, the powder feeding speed is 3g / min, and the overlap rate is 35%.

[0137] The VCoNi-based medium-entropy alloys obtained in Examples 1-9 above mainly consist of a face-centered cubic (FCC) matrix phase and L... 12 Phase, BCC phase and σ phase (e.g.) Figure 2 , 3 (As shown in the table), where the proportion of each phase and the mechanical properties of the VCoNi system entropy alloy are shown in Table 1.

[0138] Comparative Example 1

[0139] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, whose chemical composition differs from that of Example 3, specifically: V: 30.7%, Co: 38.7%, Ni: 25.9%, Al: 4.6%, C: 0.003%, H: 5ppm, N: 85ppm, O: 103ppm, with the balance being unavoidable impurities.

[0140] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The laser melting deposition and heat treatment process steps and parameters are the same as those in Example 3. The difference is that the VCoNi medium-entropy alloy powder provided in this comparative example is used.

[0141] In this comparative example, the V content of the VCoNi-based entropy alloy powder is higher than that in the example powder, while the Ni content is lower. The microstructure of the VCoNi-based entropy alloy in this comparative example mainly consists of an FCC matrix, a BCC phase, and L... 12 Phases and σ phases; of which, by volume percentage, the BCC phase is approximately 6.8%, and the L phase is approximately 6.8%. 12 The entropy content is approximately 17.3%, and the σ content is approximately 2.7%. The mechanical properties of the VCoNi system medium entropy alloys in this comparative example are shown in Table 1.

[0142] Comparative Example 2

[0143] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, whose chemical composition differs from that of Example 3, specifically: V: 28.2%, Co: 36.9%, Ni: 30.5%, Al: 4.3%, C: 0.006%, H: 5ppm, N: 93ppm, O: 120ppm, with the balance being unavoidable impurities.

[0144] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The laser melting deposition and heat treatment process steps and parameters are the same as those in Example 3. The difference is that the VCoNi medium-entropy alloy powder provided in this comparative example is used.

[0145] In this comparative example, the Ni content of the VCoNi-based entropy alloy powder is higher than that in the example powder, while the V and Co contents are lower. The microstructure of the VCoNi-based entropy alloy in this comparative example mainly consists of an FCC matrix, a BCC phase, and L... 12 Phases and σ phases; of which, by volume percentage, BCC phase is approximately 5.9%, L 12 The entropy content is approximately 16.1%, and the σ content is approximately 1.0%. The mechanical properties of the VCoNi system medium-entropy alloys in this comparative example are shown in Table 1.

[0146] Comparative Example 3

[0147] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, whose chemical composition differs from that of Example 3, specifically: V: 30.3%, Co: 38.8%, Ni: 27.3%, Al: 3.5%, C: 0.004%, H: 4ppm, N: 79ppm, O: 91ppm, with the balance being unavoidable impurities.

[0148] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The laser melting deposition and heat treatment process steps and parameters are the same as those in Example 3. The difference is that the VCoNi medium-entropy alloy powder provided in this comparative example is used.

[0149] In this comparative example, the Al content of the VCoNi-based entropy alloy powder is lower than that in the powder of the example. The microstructure of the VCoNi-based entropy alloy in this comparative example mainly consists of an FCC matrix, a BCC phase, and L... 12 The phases are BCC and σ phases; by volume percentage, BCC phase is approximately 4.3%, L12 phase is approximately 14.1%, and σ phase is approximately 1.4%. The mechanical properties of the VCoNi system medium entropy alloys in this comparative example are shown in Table 1.

[0150] Comparative Example 4

[0151] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, whose chemical composition differs from that of Example 3, specifically: V: 30.3%, Co: 39.5%, Ni: 24.6%, Al: 5.5%, C: 0.007%, H: 4ppm, N: 85ppm, O: 150ppm, with the balance being unavoidable impurities.

[0152] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The laser melting deposition and heat treatment process steps and parameters are the same as those in Example 3. The difference is that the VCoNi medium-entropy alloy powder provided in this comparative example is used.

[0153] Comparative Example 5

[0154] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, whose chemical composition differs from that of Example 3, specifically: V: 29.9%, Co: 38.2%, Ni: 27.4%, Al: 4.4%, C: 0.045%, H: 3ppm, N: 65ppm, O: 140ppm, with the balance being unavoidable impurities.

[0155] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The laser melting deposition and heat treatment process steps and parameters are the same as those in Example 3. The difference is that the VCoNi medium-entropy alloy powder provided in this comparative example is used.

[0156] Comparative Example 6

[0157] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0158] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition and heat treatment process are the same as those in Example 3. The difference lies in the laser melting deposition process parameters. In this comparative example, the laser power is 3000W, the spot diameter is 6mm, the scanning speed is 0.25m / min, the powder feeding speed is 2g / min, and the overlap rate is 55%.

[0159] Comparative Example 7

[0160] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0161] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition and heat treatment process are the same as those in Example 3. The difference lies in the laser melting deposition process parameters. In this comparative example, the laser power is 1400W, the spot diameter is 1mm, the scanning speed is 0.70m / min, the powder feeding speed is 9g / min, and the overlap rate is 30%.

[0162] Comparative Example 8

[0163] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0164] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The composition of the VCoNi medium-entropy alloy powder and the laser melting deposition process steps and parameters are the same as those in Example 3. The difference is that the first holding temperature of the two-step heat treatment is 1050℃.

[0165] Comparative Example 9

[0166] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0167] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The composition of the VCoNi medium-entropy alloy powder and the laser melting deposition process steps and parameters are the same as those in Example 3. The difference is that the first holding temperature of the two-step heat treatment is 1250℃.

[0168] Comparative Example 10

[0169] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0170] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The composition of the VCoNi medium-entropy alloy powder and the laser melting deposition process steps and parameters are the same as those in Example 3. The difference is that the second holding temperature of the two-step heat treatment is 780℃.

[0171] Comparative Example 11

[0172] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0173] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi medium-entropy alloy. The composition of the VCoNi medium-entropy alloy powder and the laser melting deposition process steps and parameters are the same as those in Example 3. The difference is that the second holding temperature of the two-step heat treatment is 880℃.

[0174] Comparative Example 12

[0175] This comparative example provides a VCoNi-based medium-entropy alloy powder for additive manufacturing, with the same chemical composition as in Example 3.

[0176] This comparative example provides a method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy. The VCoNi-based medium-entropy alloy powder composition and laser melting deposition process steps and parameters are the same as in Example 3, except for the holding temperature and time of the two heat treatment steps. In this comparative example,

[0177] Step 1: Hold at 1000℃ for 60 hours, then cool by water quenching;

[0178] Step 2: Hold at 880℃ for 0.5 hours, then cool by water quenching.

[0179] Table 1 Test results of the examples and comparative examples

[0180]

[0181]

[0182] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A VCoNi-based medium-entropy alloy powder for additive manufacturing, characterized in that, The chemical composition of the VCoNi-based entropy alloy powder, by mass percentage, includes: V: 29.5%–30.5%, Co: 37.5%–39.0%, Ni: 26.5%–28.0%, Al: 3.8%–4.9%, C: 0.003%–0.03%, H: ≤5ppm, N: ≤100ppm, O: ≤200ppm.

2. The VCoNi-based medium-entropy alloy powder according to claim 1, characterized in that, The VCoNi-based entropy alloy powder satisfies at least one of the following characteristics: (1) The particle size range is 53μm~120μm; (2) Sphericity ≥ 90%; (3) Flowability ≤15g / 50s; (4) Hollow pasta content ≤ 0.1%.

3. A method for preparing a multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy, characterized in that, Includes the following steps: (1) Provide VCoNi-based medium-entropy alloy powder, wherein the chemical composition of the VCoNi-based medium-entropy alloy powder comprises, by mass percentage: V: 29.5%–30.5%, Co: 37.5%–39.0%, Ni: 26.5%–28.0%, Al: 3.8%–4.9%, C: 0.003%–0.03%, H: ≤5ppm, N: ≤100ppm, O: ≤200ppm; Using the VCoNi-based medium-entropy alloy powder, an additive manufacturing blank is obtained by layer-by-layer forming through laser melting deposition process; (2) The additively manufactured preform is subjected to two heat treatments in sequence: Step 1: Perform heat treatment at 1100℃~1200℃; Step 2: Heat treatment at 800℃~850℃.

4. The preparation method according to claim 3, characterized in that, The heat treatment in step (2) is held for 24h to 48h, and water quenching is used after the heat treatment; the heat treatment in step (2) is held for 1h to 2h, and water quenching is used after the heat treatment.

5. The preparation method according to claim 3, characterized in that, The parameters used in the laser melting deposition process include: laser power of 1600W to 2600W, scanning speed of 0.36m / min to 0.60m / min, and powder feeding speed of 4g / min to 8g / min; and / or, The overlap rate is 40% to 50%.

6. The preparation method according to claim 3, characterized in that, The laser melting deposition process employs a forming path strategy of single-layer serpentine reciprocating scanning and interlayer rotation of 60–120°.

7. A multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy, characterized in that, It is prepared by any one of claims 3 to 6.

8. The multiphase heterogeneous high-strength VCoNi medium-entropy alloy according to claim 7, characterized in that, The microstructure of the multiphase heterogeneous high-strength VCoNi-based medium-entropy alloy includes a face-centered cubic (FCC) matrix phase and an L... 12 The phases are BCC phase and σ phase, with the BCC phase comprising 5% to 7% by volume, and the L phase comprising... 12 The content of the phase is 16% to 18%, and the content of the σ phase is 1% to 2%.

9. The multiphase heterogeneous high-strength VCoNi medium-entropy alloy according to claim 7, characterized in that, The room temperature mechanical properties of the multiphase heterogeneous high-strength VCoNi medium-entropy alloy meet the following requirements: tensile strength ≥1800MPa, yield strength ≥1500MPa, and elongation after fracture ≥25%.

10. The application of the multiphase heterogeneous high-strength VCoNi medium-entropy alloy prepared by the preparation method according to any one of claims 3 to 6, or the multiphase heterogeneous high-strength VCoNi medium-entropy alloy according to any one of claims 7 to 9, in the fields of aerospace, high-strength structural components, or complex integrated component manufacturing.

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