CoCrFeNi high-entropy alloy prepared by lpbf and method
Patent Information
- Application Number
- CN202611114210.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-27
- Publication Date
- 2026-08-21
AI Technical Summary
然而，铸态CoCrFeNi合金的屈服强度较低，限制了其在高强材料需求行业的应用
通过LPBF（激光粉末床熔融）技术制备CoCrFeNi高熵合金的方法，通过在特定VED和扫描速度范围内对CoCrFeNi高熵合金粉末进行增材制造，实现CoCrFeNi高熵合金的晶粒细化，减少缩孔，从而实现高熵合金强度和塑性的协同提升。随着VED和扫描速度的提升，晶粒细化的程度会显著增强，能显著阻碍位错运动，有效提高材料的屈服强度和断裂强度。
Smart Images
Figure CN122606008A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-entropy alloy material processing technology, and in particular to a CoCrFeNi high-entropy alloy and method prepared by LPBF. Background Technology
[0002] Alloying is a traditional method for improving the properties of metals, typically achieved by mixing a main element with a small amount of other materials. However, the advent of high-entropy alloys (HEAs) has revolutionized this approach. CoCrFeNi HEAs are typical single-phase HEAs, usually exhibiting a face-centered cubic (FCC) structure, which allows them to maintain good ductility even at extremely low temperatures. However, the low yield strength of as-cast CoCrFeNi alloys limits their application in industries requiring high-strength materials. To address this issue, researchers have begun employing additive manufacturing technologies such as laser powder bed melting (LPBF) due to their high precision and flexible processing capabilities.
[0003] Laser powder bed melting (LPBF) rapidly melts metal powder using a high-power laser, exhibiting an ultra-high cooling rate (10⁻⁶). 3 Up to 10 8 The LPBF process generates elongated columnar grains and high-density dislocations (K / s), significantly improving material strength while maintaining ductility. Studies show that the performance of high-entropy alloys prepared by LPBF is highly dependent on process parameters such as scanning speed, laser power, and volumetric energy density (VED). Research also indicates that vaporization depth and laser parameters significantly affect the threshold between transition modes and keyhole modes, and these thresholds are applicable to different materials and powder layer thicknesses, providing a general predictive tool. Summary of the Invention
[0004] The purpose of this invention is to provide a CoCrFeNi high-entropy alloy prepared by LPBF and a method thereof. The high-entropy alloy prepared by LPBF has refined grains and improved strength and plasticity. Moreover, the method is simple, the parameters are easy to control, and it is suitable for industrial promotion and has broad application prospects.
[0005] To achieve the above objectives, the present invention provides a method for preparing a CoCrFeNi high-entropy alloy using LPBF, comprising the following steps: Step S1, Ingot Smelting: According to the chemical composition ratio of CoCrFeNi high-entropy alloy, weigh pure element particles of Ni, Co, Cr and Fe with a purity greater than 99.9% and smelt them in a high vacuum induction melting furnace. Step S2, Gas atomization: The smelted CoCrFeNi high-entropy alloy sample is subjected to gas atomization treatment to obtain CoCrFeNi high-entropy alloy powder; Step S3, Laser Powder Bed Fusion (LPBF): The CoCrFeNi high-entropy alloy powder obtained in step S2 is used for LPBF to obtain the CoCrFeNi high-entropy alloy. The volumetric energy density is 120-160 J / mm². 3 The scanning speed v is 600-1000 mm / s.
[0006] Preferably, the mass percentage of each element in the CoCrFeNi high-entropy alloy is as follows: Ni: 23.00~28.00%, Co: 23.00~28.00%, Cr: 23.00~28.00%, Fe: 23.00~28.00%.
[0007] Preferably, in S2, the obtained powder particle size range is 15-53 μm.
[0008] Preferably, the spot size is 60μm and the layer thickness is 10-50μm.
[0009] Preferably, in S1, the furnace cavity is evacuated to 5×10⁻⁶ m³ / h before melting. -3 ~5×10 -2 Pa, and replaced with argon gas with a purity of not less than 99.999% 2 to 3 times; the argon gas pressure in the furnace during melting is 0.03 to 0.08 MPa, the melting temperature is 1550 to 1650℃, and the furnace is kept at a constant temperature for 5 to 20 minutes after melting. The ingot is turned over and remelted at least 5 times during the melting process.
[0010] Preferably, in step S2, the CoCrFeNi alloy ingot is subjected to vacuum induction remelting before gas atomization. The melt temperature is 1550–1650°C or 80–200°C above the alloy liquidus line, and the temperature is held for 5–20 min. Argon gas with a purity of not less than 99.999% is used as the atomization medium, the atomization pressure is 3–6 MPa, the nozzle orifice diameter is 2.0–3.0 mm, the oxygen content in the atomization tower is not higher than 100 ppm, and after cooling and collection, it is sieved in an inert atmosphere to obtain powder with a particle size of 15–53 μm.
[0011] Preferably, in step S1, the smelting process is carried out in a high-purity argon atmosphere, and the ingot is turned over and remelted at least 5 times during the smelting process.
[0012] Preferably, in S3, the volumetric energy density is 120, 140, or 160 J / mm². 3 .
[0013] Preferably, in S3, the scanning speed is 600, 800 or 1000 mm / s.
[0014] Preferably, the tensile strength is not less than 500 MPa and the elongation is not less than 20%.
[0015] Therefore, the present invention employs the above-mentioned method for preparing a CoCrFeNi high-entropy alloy using LPBF, and the technical effects are as follows: A method for preparing CoCrFeNi high-entropy alloys using LPBF (laser bed fusion) technology involves additive manufacturing of CoCrFeNi high-entropy alloy powder within a specific VED (visual enhancement) and scanning speed range. This process refines the grain size of the CoCrFeNi high-entropy alloy, reduces shrinkage cavities, and thus achieves a synergistic improvement in the strength and plasticity of the high-entropy alloy. As the VED and scanning speed increase, the degree of grain refinement significantly enhances, effectively hindering dislocation movement and improving the yield strength and fracture strength of the material.
[0016] Optimize the strength-toughness matching relationship: While maintaining high strength, effectively control the uniformity of the microstructure and the grain size, so that the material still has good elongation (≥20%), which solves the common contradiction between strength and toughness in high-entropy alloys.
[0017] Compared to existing technologies that rely solely on composition design or lack systematic heat treatment, the process method of this invention is not only simple to operate and highly repeatable, but also significantly improves material properties without the need for complex multi-stage processing or expensive equipment, exhibiting excellent process controllability and industrialization potential. Therefore, this method provides a practical, efficient, and low-cost solution for the development of high-entropy alloys for high-performance structures. Attached Figure Description
[0018] Figure 1 When VED = 140 J / mm 3 EBSD images at different scan speeds Figure 1 (a) is the EBSD image of the cross section at a scanning speed of 600 mm / s. Figure 1 (b) is the EBSD image of the cross section at a scanning speed of 800 mm / s. Figure 1 (c) is the EBSD image of the cross section at a scanning speed of 1000 mm / s; Figure 1 (d) is the EBSD image of the longitudinal section at a scanning speed of 600 mm / s. Figure 1 (e) is the EBSD image of the longitudinal section at a scanning speed of 800 mm / s. Figure 1 (f) is the EBSD image of the longitudinal section at a scanning speed of 1000 mm / s; Figure 2 When VED = 140 J / mm 3 Grain size images at different scanning speeds Figure 2 (a) Grain size diagram at a scanning speed of 600 mm / s. Figure 2 (b) shows the grain size at a scanning speed of 800 mm / s. Figure 2 (c) Grain size diagram at a scanning speed of 1000 mm / s; Figure 3 Stress-strain curves of CoCrFeNi high-entropy alloy specimens prepared with different LPBF parameters. Figure 3 (a) is 120 J / mm 3 Stress-strain curves under VED Figure 3 (b) is 140 J / mm 3 Stress-strain curves under VED Figure 3 (c) is 160 J / mm 3 Stress-strain curves under VED. Detailed Implementation
[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0020] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.
[0021] Experimental Example 1 This embodiment provides a method for preparing high-entropy CoCrFeNi alloys using LPBF technology, specifically including the following steps: Step 1: Ingot Melting Particles of Co, Cr, Fe, and Ni with an atomic percentage of Co:25:25:25:25 were weighed out, with a purity of not less than 99.9%, and placed in a high-vacuum induction melting furnace. Before melting, the furnace cavity was evacuated to a vacuum of 5 × 10⁻⁶. - 2 The furnace was purged twice with argon gas of not less than 99.999% purity. The argon pressure inside the furnace during melting was 0.05 MPa, and the melting temperature was 1600℃. After melting, the furnace was held at that temperature for 10 min. To ensure compositional uniformity, the ingot was turned over and remelted at least five times during the melting process, and finally cast to obtain a CoCrFeNi high-entropy alloy ingot.
[0022] Step 2: Atomization Before atomization, the CoCrFeNi alloy ingot was vacuum induction remelted at 1600℃ for 10 minutes. Argon gas with a purity of at least 99.999% was used as the atomization medium at a pressure of 5 MPa and a nozzle orifice diameter of 2.0 mm. The guide tube or tundish was preheated to 1000℃, and the oxygen content in the atomization tower was no higher than 100 ppm. The resulting powder had a particle size ranging from 15 to 53 μm. The obtained powder was spherical or nearly spherical with a D50 of 25–40 μm, an oxygen content no higher than 1000 ppm, and a nitrogen content no higher than 300 ppm. After vacuum drying at 100℃ for 6 hours, the CoCrFeNi high-entropy alloy powder was obtained and stored in a sealed container under vacuum or an inert atmosphere.
[0023] Step 3: LPBF LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 120 J / mm². 3 The scanning speed v is 600 mm / s, the spot size is 60 μm, and the layer thickness is 10 μm.
[0024] Step 4: Performance Testing The processed samples were processed into standard tensile specimens by wire electrical discharge machining (EDM), and the surface was then finely ground again with 400-3000 grit sandpaper. Tensile properties were tested using a universal testing machine with an extensometer (Epsilon 3442) with a gauge length of 10 mm, a tensile rate of 0.5 mm / min, and a maximum load of 100 kN.
[0025] See Figure 3 The stress-strain curve at 120 J / mm 3 Under LPBF conditions of ×600 mm / s, the fracture strength of the sample increased to 521±3.69 MPa, and the elongation was 20.9±1.63%.
[0026] Experiment Example 2 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 120 J / mm². 3 The scanning speed v is 800 mm / s.
[0027] Step 4: Performance Testing See Figure 3 The stress-strain curve at 120 J / mm 3 Under the LPBF condition of ×800mm / s, the fracture strength of the sample increased to 533±4.53MPa, and the elongation was 24.3±0.69%.
[0028] Experimental Example 3 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 120 J / mm². 3 The scanning speed v is 1000 mm / s.
[0029] Step 4: Performance Testing See Figure 3 The stress-strain curve at 120 J / mm 3 Under LPBF conditions of ×1000mm / s, the fracture strength of the sample increased to 573±2.23MPa, and the elongation was 22.2±1.59%.
[0030] Experiment Example 4 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 140 J / mm². 3 The scanning speed v was 600 mm / s. The resulting EBSD image of the high-entropy alloy is shown below. Figure 1 (a) and Figure 1 As shown in (d), the grain size of the obtained high-entropy alloy is as follows. Figure 2 As shown in (a).
[0031] Step 4: Performance Testing See Figure 3 The stress-strain curve at 140 J / mm 3 Under the LPBF condition of ×600mm / s, the fracture strength of the sample increased to 725±3.64MPa and the elongation was 41.5±1.42%.
[0032] Experimental Example 5 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 140 J / mm². 3 The scanning speed v was 800 mm / s. The resulting EBSD image of the high-entropy alloy is shown below. Figure 1 (b) and Figure 1 As shown in (e), the grain size of the obtained high-entropy alloy is as follows. Figure 2 As shown in (b).
[0033] Step 4: Performance Testing See Figure 3 The stress-strain curve at 140 J / mm 3Under the LPBF condition of ×800mm / s, the fracture strength of the sample increased to 751±6.37MPa, and the elongation was 40.2±1.22%.
[0034] Experimental Example 6 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 140 J / mm². 3 The scanning speed v was 1000 mm / s. The resulting EBSD image of the high-entropy alloy is shown below. Figure 1 (c) and Figure 1 As shown in (f), the grain size of the obtained high-entropy alloy is as follows. Figure 2 As shown in (c).
[0035] Step 4: Performance Testing See Figure 3 The stress-strain curve at 140 J / mm 3 Under LPBF conditions of ×1000mm / s, the fracture strength of the sample increased to 819±7.12MPa, and the elongation was 38.8±3.12%.
[0036] Experimental Example 7 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 160 J / mm². 3 The scanning speed v is 600 mm / s.
[0037] Step 4: Performance Testing See Figure 3 The stress-strain curve in the figure, at 160 J / mm 3 Under LPBF conditions of ×600 mm / s, the fracture strength of the sample increased to 699 ± 2.35 MPa, and the elongation was 34.3 ± 2.89%.
[0038] Experimental Example 8 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 160 J / mm². 3 The scanning speed v is 800 mm / s.
[0039] Step 4: Performance Testing See Figure 3 The stress-strain curve in the figure, at 160 J / mm 3Under the LPBF condition of ×800mm / s, the fracture strength of the sample increased to 723±5.45MPa and the elongation was 35.7±0.79%.
[0040] Experimental Example 9 The other preparation steps are the same as in Example 1, except that: LPBF was performed using the powder obtained in step 2, and the VED (volume energy density) was 160 J / mm². 3 The scanning speed v is 1000 mm / s.
[0041] Step 4: Performance Testing See Figure 3 The stress-strain curve in the figure, at 160 J / mm 3 Under the LPBF condition of ×1000mm / s, the fracture strength of the sample increased to 765±7.21MPa, and the elongation was 35.1±5.91%.
[0042] Comparative experiments show that the fracture strength of the CoCrFeNi high-entropy alloy treated with the method described in this invention can be increased from 655 MPa in the as-cast state to over 800 MPa, while the elongation remains above 20%. This indicates that the process improves the material strength without significantly sacrificing ductility, demonstrating a good strength-toughness balance. Especially at VED=140 J / mm 3 Under the condition of a scanning speed of 1000 mm / s, the fracture strength of the sample reached 819 ± 7.12 MPa and the elongation was 38.8 ± 0.96%, which is the best performance matching.
[0043] Therefore, this invention employs the aforementioned method for preparing CoCrFeNi high-entropy alloys using LPBF. By systematically controlling the heat treatment temperature and time parameters, it achieves optimized control of the microstructure of LPBF-CoCrFeNi high-entropy alloys, effectively solving the problems of insufficient strength and uneven microstructure in the traditional as-cast state. This provides a stable and reproducible processing path for the engineering application of high-performance high-entropy structural materials.
[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing CoCrFeNi high-entropy alloys using LPBF, characterized in that, Includes the following steps: Step S1, Ingot Smelting: According to the chemical composition ratio of CoCrFeNi high-entropy alloy, weigh pure element particles of Ni, Co, Cr and Fe with a purity greater than 99.9% and smelt them in a high vacuum induction melting furnace. Step S2, Gas atomization: The smelted CoCrFeNi high-entropy alloy sample is subjected to gas atomization treatment to obtain CoCrFeNi high-entropy alloy powder; Step S3, Laser Powder Bed Fusion (LPBF): The CoCrFeNi high-entropy alloy powder obtained in step S2 is used for LPBF to obtain the CoCrFeNi high-entropy alloy. The volumetric energy density is 120-160 J / mm². 3 The scanning speed v is 600-1000 mm / s.
2. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, The mass percentage of each element in the CoCrFeNi high-entropy alloy is as follows: Ni: 23.00~28.00%, Co: 23.00~28.00%, Cr：23.00~28.00%， Fe: 23.00~28.00%.
3. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, In S2, the obtained powder particle size range is 15-53 μm.
4. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, The spot size is 60μm and the layer thickness is 10-50μm.
5. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, In S1, the furnace cavity is evacuated to 5×10 before melting. -3 ~5×10 -2 Pa, and replaced with argon gas with a purity of not less than 99.999% 2 to 3 times; the argon gas pressure in the furnace during melting is 0.03 to 0.08 MPa, the melting temperature is 1550 to 1650℃, and the furnace is kept at a constant temperature for 5 to 20 minutes after melting. The ingot is turned over and remelted at least 5 times during the melting process.
6. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, In S2, the CoCrFeNi alloy ingot is vacuum induction remelted before gas atomization. The melt temperature is 1550–1650℃ or 80–200℃ above the alloy liquidus line, and the temperature is held for 5–20 min. Argon gas with a purity of not less than 99.999% is used as the atomization medium. The atomization pressure is 3–6 MPa, the nozzle orifice diameter is 2.0–3.0 mm, and the oxygen content in the atomization tower is not higher than 100 ppm. After cooling and collection, the powder is sieved in an inert atmosphere to obtain a particle size of 15–53 μm.
7. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, In step S1, the smelting process is carried out in a high-purity argon atmosphere, and the ingot is turned over and remelted at least 5 times during the smelting process.
8. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, In S3, the volumetric energy density is 120, 140, or 160 J / mm². 3 .
9. The method for preparing CoCrFeNi high-entropy alloy by LPBF according to claim 1, characterized in that, In S3, the scanning speed is 600, 800, or 1000 mm / s.
10. A CoCrFeNi high-entropy alloy prepared by the method according to any one of claims 1 to 9, characterized in that, The tensile strength is not less than 500 MPa, and the elongation is not less than 20%.