A method for preparing high-entropy alloy by combining direct writing 3D printing and hot isostatic pressing technology

Abstract

The application relates to a method for preparing a high-entropy alloy by combining direct writing 3D printing and hot isostatic pressing, and belongs to the field of powder metallurgy. The eutectic high-entropy alloy is composed of Al, Co, Cr, Fe and Ni according to a molar ratio of Al:Co:Cr:Fe:Ni=1:1:1:1:2.1. The preparation method is as follows: AlCoCrFeNi 2.1 The eutectic alloy powder is used as raw material, and a high-entropy alloy is prepared by combining direct writing 3D printing and hot isostatic pressing technology. The component design of the application is reasonable, the preparation process is simple, and the prepared product has low cost, can print complex structural parts and has good mechanical properties. Through process optimization, the sample has a room temperature tensile yield strength of 604+ / -20 MPa, a tensile strength of 1123+ / -15 MPa and a uniform elongation of 10+ / -2%. The product has excellent performance, low cost and can print complex structural parts, and can be used for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy, specifically relating to a method for preparing high-strength and tough eutectic high-entropy alloys by combining direct-write 3D printing technology and hot isostatic pressing post-processing. Background Technology

[0002] The multi-principal element characteristics of high-entropy alloys enable them to exhibit synergistic effects of multiple mechanisms (including dislocation mechanisms, phase transformations, and deformation twinning) during deformation, resulting in a series of excellent mechanical properties such as high strength, high hardness, high plasticity, radiation resistance, high-temperature softening resistance, and wear resistance. However, high-entropy alloys with specific lattice types often possess only one or a few of these superior properties. Single-phase FCC high-entropy alloys typically exhibit high plasticity but low strength, while BCC structure high-entropy alloys typically possess high strength but low plasticity. Therefore, it is difficult for these single-phase high-entropy alloys to simultaneously achieve a good balance between strength and plasticity. Furthermore, the poor castability and fluidity of single-phase high-entropy alloys, along with defects such as compositional segregation, limit their application in practical industrial production.

[0003] To solve this problem, in 2014, Lu Yiping's team at Dalian University of Technology ingeniously combined the highly ductile FCC phase with the high-strength BCC phase to design an AlCoCrFeNi... 2.1 Eutectic high-entropy alloys. These novel high-entropy alloys possess excellent strength-plasticity matching, castability, and fluidity, making them highly valuable for industrial applications. As a low-cost, scalable indirect additive manufacturing technology, direct-write 3D printing (also known as ink-based direct-write, DIW) can rapidly and precisely manufacture parts of any complex shape, achieving true "free manufacturing." Compared to laser additive manufacturing, direct-write 3D printing offers the following advantages: it eliminates the need for high-cost heat sources, has lower equipment requirements, and uses less powder, further reducing manufacturing costs; the combination of ink-based direct-write technology and atmosphere sintering effectively reduces internal residual stress in products, minimizing the tendency for bending or cracking.

[0004] This invention utilizes AlCoCrFeNi 2.1 A series of simple, industrially feasible processes, including direct-write 3D printing technology combined with hot isostatic pressing post-processing, were used to optimize the heterostructure of eutectic high-entropy alloys. This process introduced high-density nano-precipitates for reinforcement, aiming to regulate the microstructure and improve tensile mechanical properties. To date, no relevant literature has reported on this approach. Summary of the Invention

[0005] In view of the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide a method for preparing high-entropy alloys by combining direct-write 3D printing technology and hot isostatic pressing post-processing, so as to improve the above-mentioned problems.

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

[0007] A eutectic high-entropy alloy powder, wherein the eutectic high-entropy alloy is composed of Al, Co, Cr, Fe, and Ni in a molar ratio of Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1.

[0008] Preferably, the eutectic high-entropy alloy is composed of Al, Co, Cr, Fe, and Ni in a molar ratio of Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1.

[0009] The specifications of the eutectic high-entropy alloy powder are as follows: the powder particle size is less than 25 micrometers.

[0010] The preparation method of the above-mentioned eutectic high-entropy alloy includes the following preparation steps:

[0011] (1) AlCoCrFeNi 2.1 Eutectic high-entropy alloy powder is used as raw material. The eutectic high-entropy alloy is composed of Al, Co, Cr, Fe, and Ni in a molar ratio of Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1.

[0012] (2) Mix the metal raw material from step (1) with the adhesive evenly, and then use a mixer to uniformly process the mixture to obtain the required slurry.

[0013] (3) The slurry obtained in step (2) is printed in a direct-write 3D printer to obtain the green body AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0014] (4) The green blank obtained in step (3) is placed in a vacuum tube furnace for degreasing and sintering heat treatment to obtain the sintered AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0015] (5) The printed eutectic high-entropy alloy sample obtained in step (4) is placed in a hot isostatic pressing apparatus for post-processing to obtain the heat-treated AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0016] Preferably, the volume ratio of metal powder to binder in the slurry in step (2) is 70:30, 80:20, and 90:10.

[0017] Preferably, the degreasing and sintering process parameters for step (4) are: heating rate of 5-20℃ / min, maximum temperature of 1100-1400℃, holding time of 1-20 hours, and cooling with the furnace.

[0018] Preferably, the heat-treated AlCoCrFeNi obtained in step (5) 2.1Hot isostatic pressing process parameters for eutectic high entropy alloys: pressure 100-300MPa, maximum temperature 900-1300℃, heating rate 5-20℃ / min, furnace cooling.

[0019] The eutectic high-entropy alloy obtained by this invention has the following advantages and beneficial effects:

[0020] The method for preparing eutectic high-entropy alloys of this invention is simple, low-cost, and easy to mass-produce. By controlling the direct-write 3D printing process parameters and the hot isostatic pressing post-processing, high-density nano-precipitates are introduced to strengthen the heterogeneous structure, thereby controlling the microstructure and improving the tensile mechanical properties. The eutectic high-entropy alloy achieves a density of over 99.5%, a yield strength of 604±20MPa, a tensile strength of 1123±15MPa, and maintains a uniform elongation of 10±2%, effectively balancing low cost and high strength and toughness in the printing of complex structural parts using eutectic high-entropy alloys. Attached Figure Description

[0021] Figure 1 It is the sintered state AlCoCrFeNi in Embodiment 1 of the present invention. 2.1 Microstructure diagram of a eutectic high-entropy alloy.

[0022] Figure 2 It is the sintered state AlCoCrFeNi in Embodiment 1 of the present invention. 2.1 XRD pattern of eutectic high-entropy alloy.

[0023] Figure 3 It is the sintered state AlCoCrFeNi in Embodiment 1 of the present invention. 2.1 Mechanical properties of eutectic high-entropy alloys.

[0024] Figure 4 It is the thermoisostatically pressed AlCoCrFeNi in Embodiment 2 of the present invention. 2.1 Mechanical properties of eutectic high-entropy alloys. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0026] Example 1

[0027] This embodiment features a sintered AlCoCrFeNi 2.1 Preparation of eutectic high-entropy alloys:

[0028] (1) Select commercially available AlCoCrFeNi atomizing agent 2.1 Eutectic high-entropy alloy powder is used as raw material. The powder is first screened by particle size in a vibrating sieve, and powder with a particle size of less than 25 micrometers is selected for use.

[0029] (2) Mix the powder prepared in step (1) with the adhesive to form a slurry. The ratio of metal powder to adhesive is 85:15.

[0030] (3) The slurry obtained in step (2) is molded into a block green body in a direct-write 3D printer.

[0031] (4) The green billet is placed in a tube sintering furnace for degreasing and sintering to obtain a sintered eutectic high-entropy alloy. The degreasing and sintering process parameters are: heating rate of 5 / min, maximum temperature of 1250℃, holding time of 6 hours and then cooling with the furnace.

[0032] (5) The sintered AlCoCrFeNi obtained in step (4) 2.1 The eutectic high-entropy alloy was post-treated in a hot isostatic pressing furnace to obtain the hot isostatically pressed AlCoCrFeNi. 2.1 Eutectic high-entropy alloy. The hot isostatic pressing post-treatment process parameters are: sintering temperature 950℃, holding time 2 hours, pressure 150MPa, and furnace cooling.

[0033] The sintered AlCoCrFeNi obtained in this embodiment 2.1 The microstructure of eutectic high-entropy alloys, such as Figure 1 As shown. Figure 1 The sintered state AlCoCrFeNi shown 2.1 Microstructure characteristics of eutectic high-entropy alloys: Eutectic high-entropy alloys mainly exhibit an FCC+B2 dual-phase structure; the microstructure is characterized by equiaxed crystals.

[0034] The sintered AlCoCrFeNi obtained in this embodiment 2.1 The XRD pattern of the eutectic high-entropy alloy is as follows: Figure 2 As shown. Figure 2 The sintered state AlCoCrFeNi shown 2.1 XRD pattern characteristics of eutectic high-entropy alloys: The eutectic high-entropy alloys mainly contain FCC and B2 dual phases, and the presence of L12 superimposed peaks in FCC indicates the presence of L12 phase in the alloy.

[0035] The thermoisostatically pressed AlCoCrFeNi obtained in this embodiment 2.1 The tensile property spectrum of eutectic high-entropy alloys is as follows: Figure 3 As shown. Figure 3 The thermoisostatically pressed AlCoCrFeNi shown 2.1 Tensile properties of eutectic high-entropy alloys: The sintered eutectic high-entropy alloy has a yield strength of 580±10MPa, a tensile strength of 960±15MPa, and maintains an elongation after fracture of 6.5±2%.

[0036] Example 2

[0037] This embodiment describes the thermoisostatically pressed AlCoCrFeNi 2.1 Preparation of eutectic high-entropy alloys:

[0038] (1) Select commercially available AlCoCrFeNi atomizing agent 2.1 Eutectic high-entropy alloy powder is used as raw material. The powder is first screened by particle size in a vibrating sieve, and powder with a particle size of less than 25 micrometers is selected for use.

[0039] (2) Mix the powder prepared in step (1) with the adhesive to form a slurry. The ratio of metal powder to adhesive is 85:15.

[0040] (3) The slurry obtained in step (2) is molded into a block green body in a direct-write 3D printer.

[0041] (4) The green blanks are placed in a tube sintering furnace for degreasing and sintering to obtain sintered AlCoCrFeNi 2.1 Eutectic high-entropy alloy. The debinding and sintering process parameters are: heating rate of 5 / min, maximum temperature of 1250℃, holding time of 6 hours, and then cooling in the furnace.

[0042] (5) The sintered AlCoCrFeNi obtained in step (4) 2.1 The eutectic high-entropy alloy was post-treated in a hot isostatic pressing furnace to obtain the hot isostatically pressed AlCoCrFeNi. 2.1 Eutectic high-entropy alloy. The hot isostatic pressing post-treatment process parameters are: heating rate of 5℃ / min, sintering temperature of 1200℃, holding time of 2 hours, pressure of 150MPa, and furnace cooling.

[0043] The thermoisostatically pressed AlCoCrFeNi obtained in this embodiment 2.1 The mechanical properties of eutectic high-entropy alloys are as follows: Figure 4 As shown. Figure 4 The thermoisostatically pressed AlCoCrFeNi shown 2.1 Mechanical properties of eutectic high-entropy alloys. Hot isostatically pressed AlCoCrFeNi 2.1 The eutectic high-entropy alloy has a yield strength of 604±12MPa, a tensile strength of 1123±13MPa, and maintains an elongation after fracture of 10±1.5%.

[0044] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing high-entropy alloys by combining direct-write 3D printing and hot isostatic pressing, characterized in that: Includes the following steps: Step 1 With AlCoCrFeNi 2.1 Eutectic high-entropy alloy powder is used as raw material, and the raw material is mixed evenly with binder to form a slurry; Step Two The AlCoCrFeNi obtained in step one 2.1 Eutectic high-entropy alloy slurry was formed into a green body on a direct-write 3D printer; Step 3 The green blank obtained in step two, AlCoCrFeNi 2.1 The eutectic high-entropy alloy was subjected to debinding and sintering in a vacuum tube furnace to obtain sintered AlCoCrFeNi. 2.1 Eutectic high-entropy alloys; Step Four The sintered AlCoCrFeNi obtained in step three 2.1 The eutectic high-entropy alloy was post-treated in a hot isostatic pressing furnace to obtain the hot isostatically pressed AlCoCrFeNi. 2.1 Eutectic high-entropy alloy; wherein, when the hot isostatic pressing post-treatment sintering temperature is 1200℃, the holding time is 2 hours, and the pressure is 150MPa, it has the best room temperature tensile properties, with a yield strength of 604±20MPa, a tensile strength of 1123±15MPa, and a uniform elongation of 10±2%.

2. The method for preparing high-entropy alloys by combining direct-write 3D printing and hot isostatic pressing according to claim 1, characterized in that: The raw material is atomized powder with a particle size of 15-25 micrometers.

3. The method for preparing high-entropy alloys by combining direct-write 3D printing and hot isostatic pressing according to claim 1, characterized in that: In step three, the sintering process parameters are: heating rate of 5-20 ºC / min, maximum temperature of 1000-1400 ºC, and holding time of 1-20 hours; in step four, the hot isostatic pressing process parameters are: maximum temperature of 800-1300 ºC, holding time of 0.5-4 hours, and pressure of 50-200 MPa.

4. A method for preparing high-entropy alloys by combining direct-write 3D printing and hot isostatic pressing according to any one of claims 1 to 3, characterized in that: The eutectic high-entropy alloy is composed of Al, Co, Cr, Fe, and Ni in a molar ratio of Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1.

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