A high-entropy alloy and its electron beam additive manufacturing method

Abstract

This invention belongs to the field of metallic materials technology, specifically relating to a high-entropy alloy and its electron beam additive manufacturing method. The manufacturing method includes: uniformly mixing powders of tungsten, molybdenum, tantalum, niobium, boron, and silicon according to a designed composition ratio to prepare powder suitable for electron beam selective melting additive manufacturing; placing the powder in a forming chamber; and, according to set forming process parameters, melting and shaping the powder using the electron beam selective melting additive manufacturing method, layer by layer, to form a high-entropy alloy component of the desired shape. This invention solves the problems of segregation, oxidation, high brittleness, and dimensional limitations by using electron beam selective melting additive manufacturing to form high-entropy alloy materials. It achieves a stable operating temperature of 1600℃ and a strength of over 650MPa for the formed high-entropy alloy material, promoting the engineering application of ultra-high temperature high-entropy alloy materials.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials technology, specifically relating to a high-entropy alloy and its electron beam additive manufacturing method. Background Technology

[0002] With the development of aerospace technology, aircraft, engines, rocket combustion chambers, and other components are placing increasingly stringent demands on the operating temperature, lightweight design, and reusability of high-temperature resistant structural materials. Therefore, there is an urgent need to accelerate the research, development, manufacturing, and application of new high-temperature resistant alloy materials.

[0003] Ultra-high temperature high-entropy alloys generally have high densities (>12 g / cm3), and their high melting points, oxygen sensitivity, and high room temperature brittleness make their preparation and processing using traditional methods extremely difficult. Currently, the main method for preparing high-entropy alloys is vacuum melting. The main problem with vacuum melting is the limitation on casting size. If the vacuum-melted casting is large, the cooling rate is limited, making it impossible to form a uniform high-entropy alloy. Therefore, the size of vacuum-melted castings is usually no more than 5 mm * 5 mm * 30 mm, which hinders the engineering application of high-entropy alloys. Summary of the Invention

[0004] (a) Technical problems to be solved This invention addresses the above-mentioned problems by proposing a high-entropy alloy and its electron beam additive manufacturing method, aiming to solve the technical challenges of segregation, oxidation, high brittleness, and size limitations.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides an electron beam additive manufacturing method, the manufacturing method comprising: According to the designed composition ratio, the powders of tungsten, molybdenum, tantalum, niobium, boron and silicon are mixed evenly to prepare a powder suitable for electron beam selective melting additive manufacturing. The powder is placed in the forming chamber, and according to the set forming process parameters, the powder is melted and shaped using electron beam selective melting additive manufacturing method, and then deposited layer by layer to form a high-entropy alloy component of the desired shape.

[0006] Furthermore, before melting and shaping the powder, the vacuum level inside the forming chamber is maintained at 1×10⁻⁶. -3 Pa~3×10 - 3 Pa, ambient temperature is 700~850℃.

[0007] Furthermore, the forming process parameters are as follows: single-layer powder thickness 0.05~0.07mm, accelerating voltage 60KV, electron beam current 15~20mA, scanning speed 500~800mm / s, and focusing current 850~950mA.

[0008] Furthermore, the manufacturing method also includes hot isostatic pressing of the formed high-entropy alloy component.

[0009] Furthermore, the hot isostatic pressing parameters are: applying a pressure of 150 MPa at a temperature of 1500℃ and holding for 2 to 4 hours.

[0010] Furthermore, the manufacturing method also includes performing CT flaw detection on the high-entropy alloy component after it has been formed.

[0011] Furthermore, after passing the CT flaw detection, the high-entropy alloy component is prepared into a compression specimen through hot isostatic pressing and subjected to tensile strength testing. Based on the test results, the forming process parameters are adjusted, and the above forming operation is repeated until the test results meet the requirements.

[0012] Furthermore, according to the design of the powder composition, its atomic percentage is: tungsten 36.13%, molybdenum 18.85%, tantalum 35.56%, niobium 9.41%, boron 0.04%, with the balance being silicon.

[0013] Furthermore, the particle size of the powder is 45~100μm.

[0014] To achieve the above objectives, the present invention also provides a high-entropy alloy, which is manufactured using the electron beam additive manufacturing method described above.

[0015] (III) Beneficial Effects Compared with existing technologies, this invention provides a high-entropy alloy and its electron beam additive manufacturing method. By optimizing the composition design of the high-entropy alloy and controlling the element content, a small amount of Si and B elements are added to suppress oxygen embrittlement at grain boundaries, thereby improving the grain boundary bonding strength and high-temperature thermal strength. A high-entropy alloy powder specifically designed for electron beam selective melting is also provided. By using the electron beam selective melting additive manufacturing method to form this high-entropy alloy powder, the difficulties in preparation, size limitations, and uniformity problems in traditional methods can be overcome. This allows for the preparation of high-entropy alloy materials with stable operating temperatures above 1600℃ and strengths above 650MPa, meeting the engineering application requirements of ultra-high temperature high-entropy alloys. Attached Figure Description

[0016] Figure 1 Macroscopic morphology of high-entropy alloys in the deposition state for additive manufacturing.

[0017] Figure 2To develop deposited microstructures for additive manufacturing of high-entropy alloys. Detailed Implementation

[0018] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0019] This invention provides an electron beam additive manufacturing method. In one exemplary embodiment of this invention, the electron beam additive manufacturing method may include the following steps: S1. According to the designed composition ratio, mix the powders of tungsten, molybdenum, tantalum, niobium, boron and silicon evenly to prepare powder suitable for electron beam selective melting additive manufacturing. First, the active optimization design of the composition of high-entropy alloy powder for electron beam selective melting additive manufacturing is employed. Currently, over 150 types of refractory high-entropy alloy compositions exist, primarily composed of high-melting-point metallic elements such as W, Ta, Hf, Mo, Nb, Zr, V, Cr, and Ti, supplemented by lightweight elements such as Al, Ni, Re, C, B, N, and Si. The role of high-melting-point elements is to increase the alloy's service temperature, while lightweight elements help reduce the alloy's density and improve room-temperature brittleness.

[0020] However, refractory high-entropy alloys containing low-melting-point elements generally exhibit low strength at high temperatures, with the highest test temperature only reaching below 1200℃. Only two types of refractory high-entropy alloys, NbMoTaW and NbMoTaWV, reached a test temperature of 1600℃, with corresponding yield strengths of 405MPa and 477MPa, respectively.

[0021] To meet the temperature and strength requirements of high-entropy alloys in high-temperature environments, a special high-temperature, high-strength high-entropy alloy composition scheme was designed for electron beam selective melting additive manufacturing processes: tungsten (W), molybdenum (Mo), tantalum (Ta), niobium (Nb), boron (B), and silicon (Si). This high-entropy alloy can be used stably at 1600℃ and its compressive strength can reach over 650 MPa, providing an ideal performance foundation for its engineering applications.

[0022] S2. Place the powder in the forming chamber, and according to the set forming process parameters, use electron beam selective melting additive manufacturing method to melt and shape the powder, and stack it layer by layer to form a high-entropy alloy component of the required shape.

[0023] The forming chamber is a closed environment used to control the atmosphere and temperature during the manufacturing process to avoid the generation of impurities and oxidation. Two powder cylinders can be installed within the forming chamber. Using electron beam selective melting additive manufacturing, the powder placed in the forming chamber is heated and melted. An electron beam is focused onto the powder, heating it rapidly with high energy. This method has good selectivity, enabling localized melting. After the powder has melted and shaped, the position of the powder cylinders is moved or adjusted so that the next layer of powder covers the already solidified layer. This process is repeated, gradually building up each layer of melted powder until a high-entropy alloy component of the desired shape is formed.

[0024] The above steps, through optimizing the design of high-entropy alloy composition and using electron beam selective melting additive manufacturing, can produce high-entropy alloy materials with a stable operating temperature of 1600℃ and a strength of over 650MPa.

[0025] In this embodiment, the atomic percentage of the powder used for molding is as follows: tungsten 36.13%, molybdenum 18.85%, tantalum 35.56%, niobium 9.41%, boron 0.04%, and the balance is silicon.

[0026] In this embodiment, before the powder is melted and formed, the vacuum level in the forming chamber is maintained at 1×10⁻⁶. -3 Pa~3×10 - 3 Pa, ambient temperature is 700~850℃.

[0027] In this embodiment, the forming process is carried out using optimized process specifications. The specific forming process parameters are: single-layer powder thickness of 0.05~0.07mm, accelerating voltage of 60KV, electron beam current of 15~20mA, scanning speed of 500~800mm / s, and focusing current of 850~950mA.

[0028] In this embodiment, the manufacturing method further includes hot isostatic pressing of the high-entropy alloy component after forming. By applying temperature and pressure, forming defects are eliminated and the microstructure is homogenized. The hot isostatic pressing parameters are: 1500℃ + 150MPa, holding for 2 to 4 hours.

[0029] In this embodiment, quality inspection and performance testing are also included: the formed material is subjected to quality inspection, such as CT flaw detection, to ensure that the diameter of the maximum pore defect is less than 0.2 mm and there are no cracks. At the same time, compression specimens are prepared and their tensile strength at 1600°C is tested. Based on the test results, the process parameters are optimized until the requirements are met.

[0030] In addition, this embodiment also requires performance verification: performance verification and application evaluation are conducted on the high-temperature high-entropy alloy parts that meet the requirements, including strength and elongation at 1600℃. Long-term high-temperature stability testing is also performed to ensure the reliability and stability of the high-entropy alloy material.

[0031] This invention provides a high-entropy alloy. In one exemplary embodiment, the high-entropy alloy is manufactured using the method described above. The high-entropy alloy manufactured by the above method can be used at a stable operating temperature of 1600°C and possesses a compressive strength exceeding 650 MPa. Figure 1 Macroscopic morphology images of high-entropy alloys in the deposition state for additive manufacturing. Figure 2 To develop deposited microstructures for additive manufacturing of high-entropy alloys.

[0032] To better understand the above exemplary embodiments of the present invention, further descriptions are provided below with reference to specific examples, but the scope of protection of the present invention is not limited to the scope of the examples described herein.

[0033] Example 1: This embodiment is a high-temperature, high-entropy alloy electron beam selective melting additive manufacturing method, and the specific implementation steps are as follows: 1. The powder composition for molding is (WMoTaNb)SiB, with the following atomic percentages: tungsten 36.13%, molybdenum 18.85%, tantalum 35.56%, niobium 9.41%, boron 0.04%, and the balance being silicon.

[0034] 2. Mix the powders of each element according to the element ratio to form a powder for electron beam selective melting additive manufacturing, with a powder particle size of 45~100μm.

[0035] 3. The forming process parameters are as follows: preheating temperature is 750℃, single-layer powder thickness is 0.05mm, accelerating voltage is 60KV, electron beam current is 16mA, scanning speed is 800mm / s, and focusing current is 900mA.

[0036] 4. After forming, hot isostatic pressing is performed. The hot isostatic pressing process parameters are: 1500℃+150MPa, holding for 4 hours, and then removing from the furnace when the temperature drops below 200℃.

[0037] 5. The compressive properties of the molded material were tested at 1600℃. The test results showed that at 1600℃, its strength was 680~700MPa and its elongation reached 20~25%. After holding at 1600℃ for 2 hours, the high-temperature compressive strength at 1600℃ was re-measured, and it was found that the strength decreased by no more than 10%.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electron beam additive manufacturing method, characterized in that, The manufacturing method includes: According to the designed composition ratio, the powders of tungsten, molybdenum, tantalum, niobium, boron, and silicon are mixed evenly to prepare a powder suitable for electron beam selective melting additive manufacturing; the atomic percentage of the powder composition for forming is as follows: tungsten 36.13%, molybdenum 18.85%, tantalum 35.56%, niobium 9.41%, boron 0.04%, with the balance being silicon; The powder is placed in the forming chamber, and according to the set forming process parameters, the powder is melted and shaped using electron beam selective melting additive manufacturing method, and then deposited layer by layer to form a high-entropy alloy component of the desired shape. The forming process parameters are: single-layer powder thickness 0.05~0.07mm, accelerating voltage 60KV, electron beam current 15~20mA, scanning speed 500~800mm / s, and focusing current 850~950mA. The manufacturing method further includes: performing CT flaw detection on the high-entropy alloy component after forming to ensure that the diameter of the maximum hole defect is less than 0.2 mm and there are no cracks.

2. The electron beam additive manufacturing method according to claim 1, characterized in that, Before melting and shaping the powder, maintain the vacuum level in the forming chamber at 1×10⁻⁶. -3 Pa~3×10 -3 Pa, ambient temperature is 700~850℃.

3. The electron beam additive manufacturing method according to claim 1, characterized in that, The manufacturing method further includes hot isostatic pressing of the high-entropy alloy component after it has been formed.

4. The electron beam additive manufacturing method according to claim 3, characterized in that, The hot isostatic pressing parameters are: applying a pressure of 150 MPa at a temperature of 1500℃ and holding for 2-4 hours.

5. The electron beam additive manufacturing method according to claim 1, characterized in that, After passing the CT flaw detection, the high-entropy alloy component is prepared into a compression specimen by hot isostatic pressing and then subjected to tensile strength testing. Based on the test results, adjust the forming process parameters and repeat the forming operation until the test results meet the requirements.

6. The electron beam additive manufacturing method according to claim 1, characterized in that, The particle size of the powder is 45~100μm.

7. A high-entropy alloy, characterized in that, It is manufactured using the electron beam additive manufacturing method according to any one of claims 1-6.

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