Selective laser melting cobalt-chromium-iron-nickel-based multi-principal-element alloy and synthesis method thereof

Abstract

The invention discloses a selective laser melting cobalt-chromium-iron-nickel-based multi-principal-element alloy and a synthesis method thereof, and belongs to the technical field of engineering materials. Comprising the following steps that the cobalt-chromium-nickel-iron-based high-entropy alloy composite material is mainly composed of Co, Cr, Ni, Fe, Al, Ti, B, Si and C, the cobalt-chromium-nickel-iron-based high-entropy alloy composite material comprises x wt.% of Co < 34 > Cr32Ni27Al4Ti3 + y wt.% of Fe < 75 > Si10B9Cr3C3, the Co < 34 > Cr32Ni27Al4Ti3 is in a polycrystalline form, and the Fe < 75 > Si10B9Cr3C3 is in an amorphous form; wherein x and y respectively represent the mass fractions of the corresponding components, x + y = 100, and x is more than or equal to 70 and less than or equal to 95. According to the selective laser melting cobalt-chromium-nickel-iron-based high-entropy alloy material, the high-entropy alloy powder and the amorphous powder are mixed, the cobalt-chromium-nickel-iron-based high-entropy alloy material is obtained through selective laser melting, after heat treatment, the tensile strength and the yield strength reach Hv1540 and 1100 MPa, and meanwhile the elongation at break reaches 21.52%.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering materials, and particularly relates to a selective laser melting cobalt-chromium-iron-nickel-based multi-principal element alloy and a synthesis method thereof. Background Art

[0002] Compared with traditional metal material forming methods, the selective laser melting technology can directly complete the preparation of various large-sized and complex-structured metal components, and is a high-efficiency and low-cost preparation process. Therefore, the selective laser melting technology has been widely applied in the material manufacturing technical fields such as stainless steel, nickel-based alloys, and cobalt-chromium alloys. However, due to its huge residual stress and extremely high cooling rate, defects such as cracks are easily generated during the forming process. High-entropy alloys break the original way of taking one or two elements as the main elements and improving the performance by adding trace elements, and form multi-principal element alloys with four or more elements in equimolar ratio or near-equimolar ratio, and improve the performance through the unique high-entropy effect. In addition to the high-entropy effect, the slow diffusion effect in kinetics, the lattice distortion in structure, and the mixed effect in performance endow high-entropy alloys with excellent comprehensive properties, such as high hardness, high strength, high thermal stability, good wear resistance and corrosion resistance, etc. Therefore, high-entropy alloys have great application prospects in the fields of aerospace, marine equipment, etc. In recent years, selective laser melting of high-entropy alloys has become one of the research hotspots in the current material preparation field and has received great attention from scholars at home and abroad. It is very important to suppress the generation of cracks during its preparation process. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a selective laser melting cobalt-chromium-iron-nickel-based multi-principal element alloy and a synthesis method thereof. This engineering material is obtained by performing selective laser melting after mixing Co34Cr32Ni27Al4Ti3 high-entropy alloy powder and Fe75Si10B9Cr3C3 amorphous powder. After heat treatment, the tensile strength and yield strength reach Hv 1540 and 1100 MPa, respectively, and the elongation at break reaches 21.52%. The method provided by the present invention mainly uses the grain refinement caused by heterogeneous nucleation and the transformation from columnar grains to equiaxed grains in selective laser melting to suppress the generation of cracks during the selective laser melting process, and generates precipitation strengthening through heat treatment to eliminate internal stress and improve plasticity, and finally obtains a cobalt-chromium-nickel-iron-based high-entropy alloy material with excellent performance.

[0004] The first object of the present invention is to provide a cobalt-chromium-nickel-iron-based high-entropy alloy material, which is mainly composed of elements Co, Cr, Ni, Fe, Al, Ti, B, Si and C. The components of the cobalt-chromium-nickel-iron-based high-entropy alloy composite material are x wt.% (Co34Cr32Ni27Al4Ti3) + y wt.% (Fe75Si10B9Cr3C3), where Co34Cr32Ni27Al4Ti3 is in a polycrystalline form and Fe75Si10B9Cr3C3 is in an amorphous form; wherein, x and y respectively represent the mass percentages of the corresponding components, and x + y = 100, 70 ≤ x ≤ 95.

[0005] Preferably, x = 80.

[0006] The second object of the present invention is to provide a preparation method of a cobalt-chromium-nickel-iron-based high-entropy alloy material, which includes the following steps:

[0007] S1. Mix the raw material cobalt source, chromium source, nickel source, aluminum source and titanium source evenly, and then, under the protection of inert gas, repeatedly melt them four to five times at 2000 °C through a vacuum induction arc furnace to obtain a high-entropy alloy ingot with uniform composition; after powder making, high-entropy alloy powder is obtained.

[0008] S2. Mix the raw material iron source, silicon source, boron source, chromium source and carbon source evenly, and then, under the protection of inert gas, repeatedly melt them four to five times at 2000 °C through a vacuum induction arc furnace to obtain an iron-based alloy ingot. Then, the iron-based alloy is subjected to a melt rapid cooling method to obtain amorphous alloy powder;

[0009] S3. Uniformly mix the high-entropy alloy powder and the amorphous alloy powder obtained in S1 and S2 through a powder mixer at 600 revolutions per minute for 10 minutes to obtain a high-entropy alloy-amorphous alloy mixed powder with the components as described in claims 1 to 2.

[0010] S4. The uniformly mixed powder is formed through a selective laser melting device to obtain a cobalt-chromium-nickel-iron-based high-entropy alloy material.

[0011] S5. The cobalt-chromium-nickel-iron-based high-entropy alloy obtained in S4 is subjected to quenching treatment at 1100 °C for 0.5 to 24 h to obtain the cobalt-chromium-nickel-iron-based high-entropy alloy material.

[0012] Preferably, the cobalt source is pure cobalt; the chromium source is pure chromium; the nickel source is pure nickel; the iron source is pure iron. The aluminum source is pure aluminum; the titanium source is pure titanium; the silicon source is pure silicon; the boron source is pure boron; the carbon source is pure carbon

[0013] Preferably, the method for preparing the high-entropy alloy powder is the gas atomization method, and the specific steps are as follows:

[0014] Heat the high-entropy alloy ingot to complete melting. The molten droplets pass through the nozzle under the action of gravity and are dispersed and solidified under the impact of a gas medium at a certain atmospheric pressure to obtain high-entropy alloy powder.

[0015] More preferably, the atmospheric pressure is 1-10 MPa, and the atomizing medium is nitrogen.

[0016] Preferably, the method for preparing the amorphous powder is the water atomization method, and the specific steps are as follows:

[0017] Heat the iron-based alloy ingot to complete melting. The molten droplets pass through the nozzle under the action of gravity and are dispersed and rapidly solidified under the impact of a certain water pressure to obtain amorphous alloy powder.

[0018] More preferably, the water pressure is 105-110 MPa.

[0019] Preferably, the powders in S1 and S2 are uniformly mixed by a powder mixer.

[0020] Preferably, a cobalt-chromium-nickel-iron-based high-entropy alloy material is prepared by a selective laser melting equipment.

[0021] More preferably, the parameters during the forming process are: laser energy is 200 W, rotation angle is 67°, scanning speed is 950 mm / s, and powder spreading thickness is 40 μm.

[0022] Preferably, the heat treatment temperature is 1100 °C.

[0023] More preferably, the heat treatment time is 0.5 h.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The cobalt-chromium-nickel-iron-based high-entropy alloy material provided by the present invention is prepared by mixing Co34Cr32Ni27Al4Ti3 high-entropy alloy powder and Fe75Si10B9Cr3C3 amorphous powder, and after the selective laser melting process, a cobalt-chromium-nickel-iron-based high-entropy alloy material is prepared. After heat treatment, the tensile strength and yield strength reach Hv 1540, 1100 MPa, and at the same time, the elongation at break reaches 21.52%.

[0026] The present invention utilizes the grain refinement caused by heterogeneous nucleation and the transformation from columnar grains to equiaxed grains in selective laser melting to suppress the generation of cracks during the selective laser melting process, and eliminates internal stress through heat treatment to obtain an engineering material with synergistically improved strength and plasticity. Description of the Drawings

[0027] Figure 1XRD diffraction patterns of CoCrNiFe-based high-entropy alloys for Examples 1 to 3 and Comparative Example 1, where x in x% HEA is the same as x in x wt.% (Co34Cr32Ni27Al4Ti3)+y wt.% (Fe75Si10B9Cr3C3) of the material provided by the present invention;

[0028] Figure 2 IPF diagrams of CoCrNiFe-based high-entropy alloys for Examples 1 to 3 and Comparative Example 1. Among them, Figures a, b, c, and d are the IPF diagrams of Examples 1, 2, 3, and Comparative Example 1 respectively;

[0029] Figure 3 Sensitivities of columnar crystals and equiaxed crystals to cracks. Figure a is a columnar crystal, and Figure b is an equiaxed crystal;

[0030] Figure 4 TEM micrographs of the CoCrNiFe-based high-entropy alloy material of Example 3. Figure a is a TEM image, Figures b to e are HR high-resolution images of the framed area in Figure a, Figure f is a high-angle annular dark-field image of Figure a, and Figure g is an energy spectrum diagram of Figure a.

[0031] Figure 5 Tensile curves when mechanical property tests are performed on samples of x = 100, 95, 90, 80 compositions and the sample of x = 80 composition after heat treatment. The curves of the samples without heat treatment are shown in the inset. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the specific embodiments cited do not limit the present invention.

[0033] In the following embodiments, the experimental methods and detection methods are all conventional methods unless otherwise specified; the reagents and materials can all be purchased on the market unless otherwise specified.

[0034] Example 1

[0035] A preparation method of a CoCrNiFe-based high-entropy alloy material includes the following steps:

[0036] S1. Weigh the raw materials: 18.20 g of pure cobalt, 15.11 g of pure chromium, 14.40 g of pure nickel, 0.98 g of pure aluminum, and 1.31 g of pure titanium, totaling 50 g for standby; Melting: Put the raw materials into a vacuum induction arc furnace. First, evacuate the arc furnace to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), then introduce argon gas at 0.5 atm as the protective gas, strike an arc, increase the current, and melt. After complete cooling, use a robotic arm to flip the sample, and repeat the above steps four to five times to ensure its uniformity; Powder making: Put the obtained alloy ingot into a cylindrical alumina crucible, and then put the crucible into a gas atomization device. Evacuate to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), introduce the protective gas to atmospheric pressure, completely melt the alloy ingot by induction melting, let the molten liquid flow out through the bottom of the crucible, and obtain near-spherical powder after being broken by nitrogen gas with a pressure of 1 - 10 MPa and cooled.

[0037] S2. Weigh the raw materials: 44.00 g of pure iron, 2.95 g of pure silicon, 1.02 g of pure boron, 1.64 g of pure chromium, and 0.38 g of pure carbon, totaling 50 g for standby; Melting: Mix the weighed raw materials and load them into a cylindrical alumina crucible, then put the crucible into an induction melting furnace. First, evacuate the melting furnace to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), under the protection of inert gas, then introduce argon gas at 0.5 atm and start to energize the induction furnace coil for heating. Maintain the temperature between 1100 - 1250 °C for 15 minutes to ensure that all raw materials are fully melted and evenly mixed. Stop heating. After the alloy naturally cools to below 200 °C to form an alloy ingot, open the melting furnace hatch and take it out to obtain the Fe - Si - B - Cr - C master alloy; Powder making: Put the obtained alloy ingot into a cylindrical alumina crucible, and then put the crucible into a water atomization device. Evacuate to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), introduce the protective gas to atmospheric pressure, completely melt the alloy ingot by induction melting, let the molten liquid flow out through the bottom of the crucible, and obtain amorphous powder after being broken by a water flow with a water pressure of 100 - 105 MPa and rapidly cooled.

[0038] S3. Powder mixing: Weigh 475 g of the powder obtained in S1 and 25 g of the powder obtained in S2, put them into a powder mixer through the feed inlet, and mix for 80 min to obtain a mixed powder with a composition of 95 wt.%(Co₃₄Cr₃₂Ni₂₇Al₄Ti₃)+5 wt.%(Fe₇₅Si₁₀B₉Cr₃C₃).

[0039] S4. Shaping: Establish a cuboid model with dimensions of 85×14×6 mm through CAD software, import it into the slicing software to layer the model, and set the printing parameters. The set parameters are: laser energy is 200 W, rotation angle is 67°, scanning speed is 950 mm / s, and powder spreading thickness is 40 μm. Put the mixed powder into the powder bed of the selective laser melting equipment, evacuate to below 1×10⁻² Pa (reach the order of 10⁻³ Pa), introduce a protective gas (argon), and obtain a cobalt-chromium-nickel-iron-based high-entropy alloy material with a composition of 95 wt.% (Co₃₄Cr₃₂Ni₂₇Al₄Ti₃) + 5 wt.% (Fe₇₅Si₁₀B₉Cr₃C₃) after selective laser melting.

[0040] Example 2

[0041] A preparation method of a cobalt-chromium-nickel-iron-based high-entropy alloy material, comprising the following steps:

[0042] S1. Weigh the raw materials: 18.20 g of pure cobalt, 15.11 g of pure chromium, 14.40 g of pure nickel, 0.98 g of pure aluminum, and 1.31 g of pure titanium, a total of 50 g for standby; Melting: Put the raw materials into a vacuum induction arc furnace. First, evacuate the arc furnace to below 1×10⁻² Pa (reach the order of 10⁻³ Pa), then introduce 0.5 atm of argon as the protective gas, strike an arc, increase the current, and melt. After complete cooling, use a robotic arm to flip the specimen, and repeat the above steps four to five times to ensure its uniformity; Powder making: Put the obtained alloy ingot into a cylindrical alumina crucible, then put the crucible into an air atomization equipment, evacuate to below 1×10⁻² Pa (reach the order of 10⁻³ Pa), introduce the protective gas to atmospheric pressure, completely melt the alloy ingot through induction melting, let the molten liquid flow out from the bottom of the crucible, and obtain near-spherical powder after being broken by nitrogen with a pressure of 1 - 10 MPa and cooled.

[0043] S2. Weigh the raw materials. Weigh 44.00 g of pure iron, 2.95 g of pure silicon, 1.02 g of pure boron, 1.64 g of pure chromium, and 0.38 g of pure carbon, totaling 50 g, and set aside; for smelting, mix the weighed raw materials and load them into a cylindrical alumina crucible. Then, place the crucible into an induction melting furnace. First, evacuate the melting furnace to below 1×10⁻² Pa (reaching the order of 10⁻³ Pa). Under the protection of inert gas, then introduce argon at 0.5 atm and start to energize the induction furnace coil for heating. Maintain the temperature between 1100 - 1250 °C for 15 minutes to ensure that all raw materials are fully melted and evenly mixed. Stop heating. After the alloy naturally cools to below 200 °C to form an alloy ingot, open the hatch of the melting furnace and take it out to obtain the Fe-Si-B-Cr-C master alloy; for powder making, put the obtained alloy ingot into a cylindrical alumina crucible, then place the crucible into a water atomization device, evacuate to below 1×10⁻² Pa (reaching the order of 10⁻³ Pa), introduce protective gas to atmospheric pressure, completely melt the alloy ingot through induction melting, let the molten liquid flow out from the bottom of the crucible, and obtain amorphous powder after being broken by the impact of a water flow with a water pressure of 100 - 105 MPa and rapid cooling;

[0044] S3. Mix the powders. Weigh 450 g of the powder obtained in S1 and 50 g of the powder obtained in S2, put them into a powder mixer through the feed inlet, and mix for 80 min to obtain a mixed powder with a composition of 90 wt.% (Co34Cr32Ni27Al4Ti3) + 10 wt.% (Fe75Si10B9Cr3C3);

[0045] S4. Forming. Use CAD software to establish a cuboid model with dimensions of 85×14×6 mm, import it into a slicing software to layer the model, and set the printing parameters. The set parameters are: laser energy is 200 W, rotation angle is 67°, scanning speed is 950 mm / s, and powder spreading thickness is 40 μm; put the mixed powder into the powder bed of a selective laser melting device, evacuate to below 1×10⁻² Pa (reaching the order of 10⁻³ Pa), introduce protective gas (argon), and obtain a cobalt-chromium-nickel-iron-based high-entropy alloy material with a composition of 90 wt.% (Co34Cr32Ni27Al4Ti3) + 10 wt.% (Fe75Si10B9Cr3C3) after selective laser melting;

[0046] Example 3

[0047] A preparation method of a cobalt-chromium-nickel-iron-based high-entropy alloy material, comprising the following steps:

[0048] S1. Weigh the raw materials: 18.20 g of pure cobalt, 15.11 g of pure chromium, 14.40 g of pure nickel, 0.98 g of pure aluminum, and 1.31 g of pure titanium, totaling 50 g for standby; Melting: Put the raw materials into a vacuum induction arc furnace. First, evacuate the arc furnace to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), then introduce 0.5 atm of argon as the protective gas, strike an arc, increase the current, and melt. After complete cooling, use a robotic arm to flip the sample, and repeat the above steps four to five times to ensure its uniformity; Powder making: Put the obtained alloy ingot into a cylindrical alumina crucible, and then put the crucible into a gas atomization device. Evacuate to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), introduce the protective gas to atmospheric pressure, completely melt the alloy ingot through induction melting, let the molten liquid flow out from the bottom of the crucible, and obtain near-spherical powder after being broken by nitrogen with a pressure of 1 - 10 MPa and cooled.

[0049] S2. Weigh the raw materials: 44.00 g of pure iron, 2.95 g of pure silicon, 1.02 g of pure boron, 1.64 g of pure chromium, and 0.38 g of pure carbon, totaling 50 g for standby; Melting: Mix the weighed raw materials and load them into a cylindrical alumina crucible, then put the crucible into an induction melting furnace. First, evacuate the melting furnace to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), and then start to energize the induction furnace coil to heat under the protection of inert gas. Keep the temperature between 1100 - 1250 °C for 15 minutes to ensure that all raw materials are fully melted and evenly mixed. Stop heating, and open the melting furnace hatch to take out the alloy ingot after the alloy naturally cools to below 200 °C to obtain the Fe - Si - B - Cr - C master alloy; Powder making: Put the obtained alloy ingot into a cylindrical alumina crucible, and then put the crucible into a water atomization device. Evacuate to below 1×10⁻² Pa (reaching the order of magnitude of 10⁻³ Pa), introduce the protective gas to atmospheric pressure, completely melt the alloy ingot through induction melting, let the solution flow out from the bottom of the crucible, and obtain amorphous powder after being broken by a water flow with a water pressure of 100 - 105 MPa and rapidly cooled.

[0050] S3. Powder mixing: Weigh 400 g of the powder obtained in S1 and 25 g of the powder obtained in S2, put them into a powder mixer through the feed inlet, and mix for 80 min to obtain a mixed powder with a composition of 80 wt.% (Co₃₄Cr₃₂Ni₂₇Al₄Ti₃) + 20 wt.% (Fe₇₅Si₁₀B₉Cr₃C₃).

[0051] S4. Shaping: A cuboid model with dimensions of 85×14×6 mm is established using CAD software, imported into slicing software for layer slicing of the model, and printing parameters are set. The set parameters are: laser energy is 200 W, rotation angle is 67°, scanning speed is 950 mm / s, and powder spreading thickness is 40 μm. The mixed powder is placed in the powder bed of a selective laser melting equipment, evacuated to below 1×10⁻² Pa (reaching the order of 10⁻³ Pa), filled with a protective gas (argon), and after selective laser melting, a cobalt-chromium-nickel-iron-based high-entropy alloy material with a composition of 80 wt.% (Co₃₄Cr₃₂Ni₂₇Al₄Ti₃) + 20 wt.% (Fe₇₅Si₁₀B₉Cr₃C₃) is obtained.

[0052] Comparative Example 1

[0053] A preparation method of a cobalt-chromium-nickel-based high-entropy alloy material, which is different from Example 1 in that no amorphous powder is introduced, and includes the following steps:

[0054] S1. Weigh raw materials: 18.20 g of pure cobalt, 15.11 g of pure chromium, 14.40 g of pure nickel, 0.98 g of pure aluminum, and 1.31 g of pure titanium, a total of 50 g are reserved for use; Melting: The raw materials are placed in a vacuum induction arc furnace. The arc furnace is first evacuated to below 1×10⁻² Pa (reaching the order of 10⁻³ Pa), and then filled with 0.5 atm of argon as the protective gas. Arc ignition, increasing the current, and melting are carried out. After complete cooling, the sample is flipped by a robotic arm, and the above steps are repeated four to five times to ensure its uniformity; Powder making: The obtained alloy ingot is placed in a cylindrical alumina crucible, and then the crucible is placed in a gas atomization equipment. It is evacuated to below 1×10⁻² Pa (reaching the order of 10⁻³ Pa), filled with a protective gas to atmospheric pressure, and the alloy ingot is completely melted by induction melting. The solution flows out through the bottom of the crucible, is broken by nitrogen with a pressure of 1 - 10 MPa, and after cooling, near-spherical powder is obtained;

[0055] S2. Shaping: A cuboid model with dimensions of 85×14×6 mm is established using CAD software, imported into slicing software for layer slicing of the model, and printing parameters are set. The set parameters are: laser energy is 200 W, rotation angle is 67°, scanning speed is 950 mm / s, and powder spreading thickness is 40 μm. The mixed powder is placed in the powder bed of a selective laser melting equipment, evacuated to below 1×10⁻² Pa (reaching the order of 10⁻³ Pa), filled with a protective gas (argon), and after selective laser melting, a cobalt-chromium-nickel-based high-entropy alloy material with a composition of Co₃₄Cr₃₂Ni₂₇Al₄Ti₃ is obtained.

[0056] To illustrate the various properties of the CoCrNiFe-based high-entropy alloy materials prepared by the preparation method of the CoCrNiFe-based high-entropy alloy materials provided in Examples 1-3, the relevant properties of Examples 1-3, Comparative Example 1 and the CoCrNiFe-based high-entropy alloy materials proposed by the present invention were detected, as shown in Table 1.

[0057] Table 1 shows the mechanical properties after heat treatment of the components with x = 100, 95, 90, 80 and the component with x = 80.

[0058]

[0059]

[0060] Figure 1 XRD diffraction patterns of the CoCrNiFe-based high-entropy alloys of Examples 1-3 and Comparative Example 1, where x in x% HEA is consistent with x in x wt.% (Co34Cr32Ni27Al4Ti3)+y wt.% (Fe75Si10B9Cr3C3) of the material provided by the present invention. From the XRD results, it can be seen that the main microstructure of all examples is a face-centered cubic crystal structure.

[0061] Figure 2 IPF diagrams of the CoCrNiFe-based high-entropy alloys of Examples 1-3 and Comparative Example 1. Among them, Figures a, b, c, and d are the IPF diagrams of Examples 1, 2, 3, and Comparative Example 1 respectively. It can be seen from the figures that with the increase of the amorphous content, the trend of the transformation from columnar crystals to equiaxed crystals becomes more obvious.

[0062] Figure 3 Sensitivity of columnar crystals and equiaxed crystals to cracks. Figure a is columnar crystals and Figure b is equiaxed crystals, indicating that compared with the columnar crystal structure, equiaxed crystals can effectively inhibit the generation of cracks during the selective laser melting process.

[0063] Figure 4 Transmission electron microscope images of the CoCrNiFe-based high-entropy alloy of Example 3. Figure a is a transmission electron microscope image, Figures b-e are HR high-resolution images and their Fourier transform images of the framed area in Figure a, Figure f is a high-angle annular dark field image of Figure a, and Figure g is an energy spectrum diagram of Figure a. Combining Figure a, f, g, and the Fourier transform images in Figures b-e, it can be seen that in addition to the main face-centered cubic structure, there are a large number of discontinuous pure Cr precipitates, continuous TiC halo precipitates and partial dot-like Cr2Ti precipitates in the CoCrNiFe-based high-entropy alloy of Example 3. The precipitates generated during the selective laser melting process play a role in precipitation strengthening, resulting in a great improvement in the strength of Example 3 compared with Comparative Example 1.

[0064] Figure 5Tensile curves of samples with x = 100, 95, 90, 80 components and the sample with x = 80 after heat treatment during mechanical property testing. The curve of the sample without heat treatment is shown in the inset.

[0065] The theoretical analysis provided by the present invention shows that adding other iron-based amorphous alloys that cause inhibition of nucleation and precipitation strengthening in the cobalt-chromium-nickel-iron-based high-entropy alloy material can achieve a similar effect to Fe75Si10B9Cr3C3.

[0066] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, they are also regarded as including these modifications and variations.

Claims

1. A cobalt-chromium-nickel-iron based high entropy alloy material, characterized in that: It is mainly composed of elements Co, Cr, Ni, Fe, Al, Ti, B, Si and C. The composition of the cobalt-chromium-nickel-iron based high entropy alloy composite material is xwt.% (Co34Cr32Ni27Al4Ti3) + ywt.% (Fe75Si10B9Cr3C3), the Co34Cr32Ni27Al4Ti3 is in a polycrystalline form, and the Fe75Si10B9Cr3C3 is in an amorphous form; wherein x and y represent the mass percentages of the corresponding components respectively.

2. The cobalt-chromium-nickel-iron-based high entropy alloy material according to claim 1, characterized in that: x+y=100, 70≤x≤95.

3. A method for preparing the cobalt-chromium-nickel-iron based high entropy alloy material according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. After uniformly mixing the raw materials of cobalt source, chromium source, nickel source, aluminum source and titanium source, the raw materials are repeatedly smelted four to five times at 2000°C in a vacuum induction arc furnace under the protection of inert gas to obtain a high entropy alloy ingot with uniform composition; and the high entropy alloy powder is obtained after powdering. S2. After uniformly mixing the raw materials of iron source, silicon source, boron source, chromium source and carbon source, the raw materials are repeatedly melted at 2000°C four to five times in a vacuum induction arc furnace under the protection of inert gas to obtain an iron-based alloy ingot. The iron-based alloy is then rapidly cooled by a melt method to obtain an amorphous alloy powder; S3. The high entropy alloy powder and amorphous alloy powder obtained by S1 and S2 are uniformly mixed in a powder mixer at 600 rpm for 10 minutes to obtain a high entropy alloy-amorphous alloy mixed powder of the composition as described in claims 1 to 2. S4. The uniformly mixed powder is formed by a selective laser melting device to obtain a cobalt-chromium-nickel-iron based high entropy alloy material. S5. The cobalt-chromium-nickel-iron based high entropy alloy obtained in S4 is quenched at 1100° C. for 0.5 to 24 h to obtain a cobalt-chromium-nickel-iron based high entropy alloy material.

4. The method for preparing the cobalt-chromium-nickel-iron based high entropy alloy material according to claim 3, characterized in that: The cobalt source is pure cobalt; the chromium source is pure chromium; the nickel source is pure nickel; the iron source is pure iron; the aluminum source is pure aluminum; the titanium source is pure titanium; the silicon source is pure silicon; the boron source is pure boron; and the carbon source is pure carbon.

5. The method for preparing the cobalt-chromium-nickel-iron based high entropy alloy material according to claim 3, characterized in that: The high entropy alloy powder making method adopts a gas atomization method, and the specific steps are as follows: The high entropy alloy ingot is heated until it is completely melted, and the molten droplets pass through the nozzle under the applied pressure, disperse and solidify under the impact of the gas medium to obtain high entropy alloy powder.

6. The method for preparing the cobalt-chromium-nickel-iron based high entropy alloy material according to claim 5, characterized in that: The gas medium is nitrogen, and the pressure is 1-10 MPa.

7. The method for preparing the cobalt-chromium-nickel-iron based high entropy alloy material according to claim 3, characterized in that: The method for preparing powder by rapid solidification of melt is a water atomization method, and the specific steps are as follows: The iron-based alloy ingot is heated until it is completely melted, and the molten droplets pass through the nozzle under the applied pressure, disperse under the impact of water, and solidify rapidly to obtain amorphous alloy powder.

8. The method for preparing the cobalt-chromium-nickel-iron based high entropy alloy material according to claim 7, characterized in that: The pressure is 105-110 MPa.

9. The method for preparing a cobalt-chromium-nickel-iron-based high entropy alloy material according to claim 3, wherein the cobalt-chromium-nickel-iron-based high entropy alloy material having the components as claimed in claims 1 to 2 is prepared by selective laser melting, characterized in that: The laser energy is 200W, the rotation angle is 67°, the scanning speed is 950mm / s, the powder thickness is 40μm, and the laser width is 90μm.

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