High-entropy alloy powder and preparation method thereof

Abstract

The invention discloses high-entropy alloy powder and a preparation method thereof. The high-entropy alloy powder comprises the following elements in percentage by mass: 50-55% of Ni; nb: 4.75%-5.5%; 2.8% to 3.3% of Mo; 17%-21% of Cr; 0.2% to 0.8% of Al; 0.65% to 1.15% of Ti; co: less than or equal to 1.00%; b: < = 0.006%; si: less than or equal to 0.35%; mn: less than or equal to 0.35%; cu: less than or equal to 0.3%; 0.01% or less of Mg; less than or equal to 0.08% of C; less than or equal to 0.015% of S; less than or equal to 0.015% of P; and the balance of iron. The Ni raw material is hollow nano Ni powder, the Cr raw material is hollow nano Cr powder, and the Nb raw material is nano twin niobium sheets. According to the high-entropy alloy powder, the raw materials are adopted, so that a more uniform and stable high-entropy alloy phase structure can be formed, and the mechanical property of the alloy is improved.

Description

Technical Field

[0001] The present application relates to the technical field of alloy preparation, and more specifically, to a high entropy alloy powder and a preparation method thereof. Background Art

[0002] High entropy alloy is a new type of alloy. Different from traditional alloys with one or two elements as the main components, high entropy alloy refers to an alloy formed by four or more components with equal or similar molecular weight. The alloy has a single-phase solid solution structure in which the main elements are randomly mixed. This structure has a high mixing entropy, so it tends to form a high entropy solid solution with a single-phase or multi-phase simple structure, rather than a complex structure such as an intermetallic compound. This new type of alloy has a high mixing entropy effect in thermodynamics, a lattice distortion effect in structure, a diffusion hysteresis effect in kinetics, and a cocktail effect in performance. Existing research results show that high entropy alloys have some properties that are superior to traditional alloys, such as high strength, high hardness, resistance to temper softening, high wear resistance, good corrosion resistance, and special magnetic properties. It is another new frontier research field in materials science after amorphous alloys.

[0003] In the related art, for example, the patent document with the announcement number CN104841930B discloses a high entropy alloy powder for 3D printing, wherein the high entropy alloy powder is composed of Ni: 19.95%, Co: 17.55%, Cr: 22.60%, Ti: 19.95% and V: 19.95% by atomic percentage. The preparation method thereof comprises: weighing Ni powder, Co powder, Cr powder, Ti powder and V powder as raw materials according to the atomic percentage of 19.95% Ni, 17.55% Co, 22.60% Cr, 19.95% Ti and 19.95% V, and then placing the raw materials in a planetary high energy ball mill for ball milling at a speed of 300 rpm to obtain a high entropy alloy powder.

[0004] With regard to the above-mentioned related technologies, metal powder is directly used as raw material when preparing high entropy powder alloy, and then the alloy powder is obtained by ball milling. Due to the large particle size of the metal powder and the low surface energy, the contact area between the alloy elements is limited during the ball milling process, the diffusion power is insufficient, and it is difficult to form a stable high entropy alloy phase structure, thereby affecting the mechanical properties of the alloy. Summary of the invention

[0005] In order to enhance the mechanical properties of high entropy alloys, the present application provides a high entropy alloy powder and a preparation method thereof.

[0006] The high entropy alloy powder provided in this application adopts the following technical solution: A high entropy alloy powder, comprising, by element mass percentage: Ni: 50%-55%; Nb: 4.75%-5.5%; Mo: 2.8%-3.3%; Cr: 17%-21%; Al: 0.2%-0.8%; Ti: 0.65%-1.15%; Co: ≤1.00%; B: ≤0.006%; Si: ≤0.35%; Mn: ≤0.35%; Cu: ≤0.3%; Mg: ≤0.01%; C: ≤0.08%; S: ≤0.015%; P: ≤0.015%; the balance is iron; The Ni raw material is hollow nano Ni powder, the Cr raw material is hollow nano Cr powder, and the Nb raw material is nano twin niobium flakes.

[0007] By adopting the above technical scheme, the main metal raw materials of the high entropy alloy powder are hollow nano Ni powder, hollow nano Cr powder and nano twin niobium flakes. Hollow nano powder has a large specific surface area, which enables the metal raw material powder to fully contact with other metal elements during the alloying process, increase the reactive sites, promote the diffusion and uniform mixing between the alloy elements, and is conducive to the formation of a more uniform and stable high entropy alloy phase structure, thereby improving the mechanical properties of the alloy. In high entropy alloys, nano-sized hollow powder can effectively hinder the movement of dislocations, and significantly improve the strength and toughness of the alloy. The introduction of nano twin niobium flakes helps to refine the grains of high entropy alloys. Refined grains can increase the number of grain boundaries, further hinder the movement of dislocations, and improve the strength and toughness of the material. The twin boundaries in the nano twin structure, as additional obstacles, can significantly hinder the movement of dislocations. When dislocations propagate in the alloy, they encounter twin boundaries and are forced to change direction or stop, thereby consuming energy and improving the strength of the material. In summary, the synergistic effect of nano-twinned niobium sheets and hollow nanopowders can form a more stable organizational structure, which can more effectively hinder the movement of dislocations and improve the strength and toughness of the alloy.

[0008] Optionally, the hollow nano Ni powder is prepared by the following method: A. Use nickel powder as evaporation source material, place the nickel powder in the evaporation chamber of the PVD equipment, and place the nano-alumina powder in the deposition chamber of the PVD equipment; B. After evacuating the PVD equipment, deposition is performed. During the deposition process, the evaporation temperature is controlled at 1500-1550°C and the deposition time is 2-3h. After the deposition is completed, a nano-nickel ball / aluminum oxide complex is obtained; the nano-nickel ball / aluminum oxide complex is added to a sodium hydroxide aqueous solution, and after magnetic stirring at 50-70°C for 1-2h, hollow nano-Ni powder is obtained by filtration, washing and drying.

[0009] Optionally, the purity of the nano alumina powder in step A is greater than 99.9%, and the average particle size of the nano alumina powder is 10-40 nm.

[0010] By adopting the above technical solution, the nickel powder is evaporated into atoms by using the evaporation and deposition process of the PVD equipment, and deposited on the nano-alumina powder to form a nano-nickel ball / alumina complex, and then the nano-alumina is dissolved and cleaned by sodium hydroxide aqueous solution to obtain hollow nano-Ni powder. By selecting high-purity nano-alumina powder as a template, it is conducive to the uniform deposition of hollow nano-Ni powder, thereby forming a more stable hollow nano structure.

[0011] Optionally, the hollow nano Cr powder is prepared by the following method: (1) Using chromium powder as an evaporation source material, placing the chromium powder in an evaporation chamber of a PVD device, and placing nano-silicon dioxide powder in a deposition chamber of the PVD device; (2) The PVD equipment is evacuated and then deposited. During the deposition process, the evaporation temperature is controlled at 1850-1900°C and the deposition time is 3-4 hours. After the deposition is completed, a nano-chromium ball / silicon dioxide composite is obtained. The nano-chromium ball / silicon dioxide composite is added to a hydrofluoric acid solution, and after magnetic stirring at 40-50°C for 1-2 hours, the hollow nano-Cr powder is obtained by filtration, washing and drying.

[0012] Optionally, the purity of the nano-silicon dioxide powder in step (1) is greater than 99.5%, and the average particle size of the nano-silicon dioxide powder is 10-50 nm.

[0013] By adopting the above technical scheme, using physical vapor deposition technology, using chromium powder as an evaporation source, and placing nano-silica powder as a template in the deposition chamber, hollow nano-Cr powder with uniform size and consistent sphericity can be prepared. By precisely controlling the evaporation temperature and deposition time, the deposition process of chromium on the silica template can be optimized to ensure that hollow nano-Cr powder with uniform structure and controllable size is obtained. Using a hydrofluoric acid solution to treat the nano-chromium ball / silica composite can efficiently remove the silica template while maintaining the structural integrity of the hollow nano-Cr powder. This method is gentler than traditional physical or mechanical removal methods and helps reduce powder breakage and agglomeration. Hollow nano-Cr powder helps to improve the strength and toughness of the final high-entropy alloy.

[0014] Optionally, the nano twinned niobium sheet is prepared by the following method: The niobium salt and sulfuric acid solution are dissolved in deionized water to prepare an electrolyte. A niobium plate is selected as an anode and a stainless steel plate is selected as a cathode. The electrodes are placed in the electrolyte for electrodeposition. After the electrodeposition is completed, the stainless steel plate is taken out and the residual electrolyte on the surface is rinsed off with deionized water. Under the protection of inert gas, after annealing, the niobium layer is separated from the stainless steel plate to obtain a nano-twinned niobium sheet.

[0015] Optionally, the niobium salt is a niobium oxalate solution, and the volume ratio of the niobium oxalate solution, the sulfuric acid solution and deionized water is 1:1:(2-3.5).

[0016] Optionally, the electrodeposition treatment parameters are: pulse current density of 10-50 mA / cm², on / off time ratio of 1:(5-10), electrolyte temperature controlled at 30-60°C, magnetic stirring at a stirring speed of 200-500 rpm, and electrodeposition time of 5-8 hours.

[0017] By adopting the above technical solution and optimizing the electrolyte ratio, the appropriate electrolyte ratio provides a good electrodeposition environment, ensuring the preparation quality of the nano-twin niobium sheet. The appropriate electrodeposition processing parameters provide good electrodeposition conditions, ensuring that the nano-twin niobium sheet has a stable nano-twin structure.

[0018] The present application also provides a method for preparing high entropy alloy powder, which adopts the following technical solution: S1. Prepare raw materials corresponding to each element according to the ratio, wherein the Ni raw material is hollow nano Ni powder, the Cr raw material is hollow nano Cr powder, the Nb raw material is nano twin niobium flakes, and the remaining elements are prepared in the form of single substance and / or alloy; S2. Mix the raw materials and smelt them under a protective atmosphere to obtain a molten alloy. Use an atomizing device to atomize the molten alloy. Use argon gas as the atomizing gas. After the atomization is completed, cool the molten alloy and wash and sieve it to obtain a high entropy alloy powder.

[0019] Optionally, during the atomization treatment in S2, the atomization gas pressure is 3-6 MPa and the atomization temperature is 1200-1500°C.

[0020] In summary, this application has the following beneficial effects: 1. The main metal raw materials of the high entropy alloy powder of the present application are hollow nano Ni powder, hollow nano Cr powder and nano twin niobium flakes. Hollow nano Ni powder and hollow nano Cr powder have a large specific surface area, which enables the metal raw material powder to fully contact with other metal elements during the alloying process, increase the reaction active sites, promote the diffusion and uniform mixing between the alloy elements, and is conducive to the formation of a more uniform and stable high entropy alloy phase structure, thereby improving the mechanical properties of the alloy. The introduction of nano twin niobium flakes helps to refine the grains of the high entropy alloy. Refined grains can increase the number of grain boundaries and further hinder the movement of dislocations, thereby enhancing the strength and toughness of the high entropy alloy material.

[0021] 2. In this application, physical vapor deposition technology is used, chromium powder or nickel powder is used as an evaporation source, and nanopowder is placed in the deposition chamber as a template to produce structurally stable hollow nano Cr powder and hollow nano Ni powder. By precisely controlling the evaporation temperature and deposition time, the deposition process of metal vapor on the template can be optimized to ensure that hollow nanopowder with uniform structure and controllable size is obtained. This method is gentler than traditional physical or mechanical removal methods, helps reduce powder breakage and agglomeration, and thus helps to improve the strength and toughness of the final high entropy alloy material.

[0022] 3. The present application optimizes the electrolyte ratio when preparing nano-twin niobium sheets. The appropriate electrolyte ratio provides a good electrodeposition environment and ensures the preparation quality of the nano-twin niobium sheets. The appropriate electrodeposition treatment parameters provide good electrodeposition conditions and ensure that the nano-twin niobium sheets have a stable nano-twin structure, which is conducive to playing a good role in hindering dislocation movement in the subsequent raw material alloying process, thereby enhancing the strength and toughness of the high entropy alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a cross-sectional SEM image of a rod sample prepared from the high entropy alloy powder of Example 1 of the present application; Figure 2 This is a cross-sectional OM morphology image of a rod sample prepared from the high entropy alloy powder of Example 1 of the present application. DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with embodiments.

[0025] Preparation example of hollow nano Ni powder Preparation Example 1 Hollow nano Ni powder is prepared by the following method: A. Using nickel powder as an evaporation source material, placing the nickel powder in an evaporation chamber of a PVD device, and placing nano-alumina powder in a deposition chamber of the PVD device; the purity of the nano-alumina powder is 99.99%, and the average particle size of the nano-alumina powder is 10 nm; B. Evacuate the PVD equipment for deposition, with a vacuum degree of 1.0×10 -4 Pa, the evaporation temperature is controlled at 1500°C and the deposition time is 3h during the deposition process, and a nano-nickel ball / alumina complex is obtained after the deposition is completed; the nano-nickel ball / alumina complex is added to a sodium hydroxide aqueous solution with a mass concentration of 25%, and after magnetic stirring at 50°C for 2h, hollow nano-Ni powder is obtained by filtration, washing and drying.

[0026] Preparation Example 2 Hollow nano Ni powder is prepared by the following method: A. Nickel powder is used as an evaporation source material, and the nickel powder is placed in the evaporation chamber of the PVD equipment, and nano-alumina powder is placed in the deposition chamber of the PVD equipment; the purity of the nano-alumina powder is 99.99%, and the average particle size of the nano-alumina powder is 25nm; B. Evacuate the PVD equipment for deposition, with a vacuum degree of 1.0×10 -4 Pa, the evaporation temperature was controlled at 1520°C and the deposition time was 2.5h during the deposition process, and a nano-nickel ball / alumina complex was obtained after the deposition was completed; the nano-nickel ball / alumina complex was added to a sodium hydroxide aqueous solution with a mass concentration of 25%, and after magnetic stirring at 60°C for 1.5h, hollow nano-Ni powder was obtained by filtration, washing and drying.

[0027] Preparation Example 3 Hollow nano Ni powder is prepared by the following method: A. Using nickel powder as an evaporation source material, placing the nickel powder in an evaporation chamber of a PVD device, and placing nano-alumina powder in a deposition chamber of the PVD device; the purity of the nano-alumina powder is 99.99%, and the average particle size of the nano-alumina powder is 40 nm; B. Evacuate the PVD equipment for deposition, with a vacuum degree of 1.0×10 -4 Pa, the evaporation temperature is controlled at 1550℃ and the deposition time is 2h during the deposition process, and a nano-nickel ball / alumina complex is obtained after the deposition is completed; the nano-nickel ball / alumina complex is added into a sodium hydroxide aqueous solution with a mass concentration of 25%, and after magnetic stirring at 70℃ for 1h, hollow nano-Ni powder is obtained by filtration, washing and drying.

[0028] Preparation example of hollow nano-Cr powder Preparation Example 4 Hollow nano Cr powder is prepared by the following method: (1) Using chromium powder as an evaporation source material, placing the chromium powder in an evaporation chamber of a PVD device, and placing nano-silicon dioxide powder in a deposition chamber of the PVD device; the purity of the nano-silicon dioxide powder is 99.5%, and the average particle size of the nano-silicon dioxide powder is 10 nm; (2) The PVD equipment was evacuated for deposition, and the vacuum degree was 1.0×10 -4 Pa, the evaporation temperature is controlled at 1850℃ and the deposition time is 4h during the deposition process, and a nano-chromium ball / silicon dioxide composite is obtained after the deposition is completed; the nano-chromium ball / silicon carbide composite is added into a hydrofluoric acid solution with a mass concentration of 15%, and after magnetic stirring at 40℃ for 2h, hollow nano-Cr powder is obtained by filtration, washing and drying.

[0029] Preparation Example 5 Hollow nano Cr powder is prepared by the following method: (1) Using chromium powder as an evaporation source material, placing the chromium powder in an evaporation chamber of a PVD device, and placing nano-silicon dioxide powder in a deposition chamber of the PVD device; the purity of the nano-silicon dioxide powder is 99.8%, and the average particle size of the nano-silicon dioxide powder is 30 nm; (2) The PVD equipment was evacuated for deposition, and the vacuum degree was 1.0×10 -4 Pa, the evaporation temperature was controlled at 1880°C and the deposition time was 3.5h during the deposition process, and a nano-chromium ball / silicon dioxide composite was obtained after the deposition was completed; the nano-chromium ball / silicon carbide composite was added to a hydrofluoric acid solution with a mass concentration of 15%, and after magnetic stirring at 45°C for 1.5h, hollow nano-Cr powder was obtained by filtration, washing and drying.

[0030] Preparation Example 6 Hollow nano Cr powder is prepared by the following method: (1) Using chromium powder as an evaporation source material, placing the chromium powder in an evaporation chamber of a PVD device, and placing nano-silicon dioxide powder in a deposition chamber of the PVD device; the purity of the nano-silicon dioxide powder is 99.9%, and the average particle size of the nano-silicon dioxide powder is 50 nm; (2) The PVD equipment was evacuated for deposition, and the vacuum degree was 1.0×10 -4 Pa, the evaporation temperature is controlled at 1900°C and the deposition time is 3h during the deposition process, and a nano-chromium ball / silicon dioxide composite is obtained after the deposition is completed; the nano-chromium ball / silicon carbide composite is added to a hydrofluoric acid solution with a mass concentration of 15%, and after magnetic stirring at 50°C for 1h, hollow nano-Cr powder is obtained by filtration, washing and drying.

[0031] Preparation example of nano twinned niobium sheets Preparation Example 7 The nano twinned niobium sheet is prepared by the following method: Dissolve 100mL of niobium oxalate solution and 100mL of sulfuric acid solution in 200mL of deionized water to prepare an electrolyte. The concentration of niobium oxalate solution is 1.0mol / L, and the concentration of sulfuric acid solution is 1.5mol / L. Use niobium plate as anode and stainless steel plate as cathode. Put the electrodes into the electrolyte for electrodeposition. The electrodeposition treatment parameters are: pulse current density is 10mA / cm², on / off time ratio is 1:5, electrolyte temperature is controlled at 30℃, and the electrolyte is magnetically stirred at a stirring speed of 200rpm during the electrolysis process. The electrodeposition time is 8h. After the electrodeposition is completed, take out the stainless steel plate, rinse the residual electrolyte on the surface with deionized water, and separate the niobium layer from the stainless steel plate after annealing under nitrogen protection to obtain nano-twinned niobium sheets.

[0032] Preparation Example 8 The nano twinned niobium sheet is prepared by the following method: Dissolve 100mL of niobium oxalate solution and 100mL of sulfuric acid solution in 300mL of deionized water to prepare an electrolyte. The concentration of niobium oxalate solution is 1.0mol / L, and the concentration of sulfuric acid solution is 1.5mol / L. Use niobium plate as anode and stainless steel plate as cathode. Put the electrodes into the electrolyte for electrodeposition. The electrodeposition treatment parameters are: pulse current density is 30mA / cm², on / off time ratio is 1:8, electrolyte temperature is controlled at 50℃, and the electrolyte is magnetically stirred at a stirring speed of 400rpm during the electrolysis process. The electrodeposition time is 6h. After the electrodeposition is completed, take out the stainless steel plate, rinse the residual electrolyte on the surface with deionized water, and separate the niobium layer from the stainless steel plate after annealing under nitrogen protection to obtain nano-twinned niobium sheets.

[0033] Preparation Example 9 The nano twinned niobium sheet is prepared by the following method: Dissolve 100mL of niobium oxalate solution and 100mL of sulfuric acid solution in 350mL of deionized water to prepare an electrolyte. The concentration of niobium oxalate solution is 1.0mol / L, and the concentration of sulfuric acid solution is 1.5mol / L. Use niobium plate as anode and stainless steel plate as cathode. Put the electrodes into the electrolyte for electrodeposition. The electrodeposition treatment parameters are: pulse current density of 50mA / cm², on / off time ratio of 1:10, electrolyte temperature controlled at 60℃, magnetic stirring of the electrolyte at a stirring speed of 500rpm during the electrolysis process, and electrodeposition time of 5h. After the electrodeposition is completed, take out the stainless steel plate, rinse the residual electrolyte on the surface with deionized water, and separate the niobium layer from the stainless steel plate after annealing under nitrogen protection to obtain nano-twinned niobium sheets.

[0034] Preparation Example 10 The nano twinned niobium sheet is different from that of Preparation Example 9 in that the pulse current density during the electrodeposition process is 10 mA / cm² and the on / off time ratio is 1:2.

[0035] Example Example 1 A high entropy alloy powder, the raw material components and dosages thereof are shown in Table 1. The Ni raw material is the hollow nano Ni powder of Preparation Example 1, the Cr raw material is the hollow nano Cr powder of Preparation Example 4, the Nb raw material is the nano twin niobium flakes of Preparation Example 7, and the remaining raw materials are all single substance powders corresponding to the elements, and the average particle size of the single substance powders is 10 μm.

[0036] The preparation method of high entropy alloy powder is as follows: S1. Prepare raw materials corresponding to each element according to the ratio, wherein the Ni raw material is the hollow nano Ni powder of Preparation Example 1, the Cr raw material is the hollow nano Cr powder of Preparation Example 4, the Nb raw material is the nano twin niobium sheet of Preparation Example 7, and the remaining elements are prepared in the form of single substance powder; S2. Mix the raw materials and smelt them under a protective atmosphere to obtain a molten alloy. Use an atomizing device to atomize the molten alloy. Use argon gas as the atomizing gas. The atomizing gas pressure is 3 MPa and the atomizing temperature is 1200° C. After the atomization is completed, cool the mixture, wash it, and sieve it to obtain a high entropy alloy powder.

[0037] Example 2 A high entropy alloy powder, the raw material components and dosages thereof are shown in Table 1. The Ni raw material is the hollow nano Ni powder of Preparation Example 2, the Cr raw material is the hollow nano Cr powder of Preparation Example 4, the Nb raw material is the nano twin niobium flake of Preparation Example 7, and the remaining raw materials are all single substance powders corresponding to the elements, and the average particle size of the single substance powders is 10 μm.

[0038] The preparation method of high entropy alloy powder is as follows: S1. Prepare raw materials corresponding to each element according to the ratio, wherein the Ni raw material is the hollow nano Ni powder of Preparation Example 2, the Cr raw material is the hollow nano Cr powder of Preparation Example 4, the Nb raw material is the nano twin niobium sheet of Preparation Example 7, and the remaining elements are prepared in the form of single substance powder; S2. Mix the raw materials and smelt them under a protective atmosphere to obtain a molten alloy. Use an atomizing device to atomize the molten alloy. Use argon gas as the atomizing gas. The atomizing gas pressure is 5 MPa and the atomizing temperature is 1300° C. After the atomization is completed, cool the mixture, wash it, and sieve it to obtain a high entropy alloy powder.

[0039] Example 3 A high entropy alloy powder, the raw material components and dosages thereof are shown in Table 1. Among them, the Ni raw material is the hollow nano Ni powder of Preparation Example 3, the Cr raw material is the hollow nano Cr powder of Preparation Example 4, the Nb raw material is the nano twin niobium sheet of Preparation Example 7, and the remaining raw materials are all single substance powders corresponding to the elements, and the average particle size of the single substance powders is 10 μm.

[0040] The preparation method of high entropy alloy powder is as follows: S1. Prepare raw materials corresponding to each element according to the ratio, wherein the Ni raw material is the hollow nano Ni powder of Preparation Example 3, the Cr raw material is the hollow nano Cr powder of Preparation Example 4, the Nb raw material is the nano twin niobium sheet of Preparation Example 7, and the remaining elements are prepared in the form of single substance powder; S2. Mix the raw materials and smelt them under a protective atmosphere to obtain a molten alloy. Use an atomizing device to atomize the molten alloy. Use argon gas as the atomizing gas. The atomizing gas pressure is 6 MPa and the atomizing temperature is 1500° C. After the atomization is completed, cool the mixture, wash it, and sieve it to obtain a high entropy alloy powder.

[0041] Table 1 High entropy alloy powder raw material components and amounts in Examples 1-3 (g)

[0042] Example 4 A high entropy alloy powder is disclosed. The difference between this embodiment and the embodiment 3 is that the Cr raw material in this embodiment is the hollow nano Cr powder of the preparation example 5.

[0043] Example 5 A high entropy alloy powder is disclosed. The difference between this embodiment and the embodiment 3 is that the Cr raw material in this embodiment is the hollow nano Cr powder of the preparation example 6.

[0044] Example 6 A high entropy alloy powder is disclosed. The difference between this embodiment and the embodiment 3 is that the Nb raw material in this embodiment is the nano-twinned niobium sheet of the preparation example 8.

[0045] Example 7 A high entropy alloy powder is disclosed. The difference between this embodiment and the embodiment 3 is that the Nb raw material in this embodiment is the nano-twinned niobium sheet of the preparation example 9.

[0046] Example 8 A high entropy alloy powder is disclosed. The difference between this embodiment and the embodiment 3 is that the Nb raw material in this embodiment is the nano-twinned niobium sheet of preparation example 10.

[0047] Comparative Example Comparative Example 1 The high entropy alloy powder was prepared according to the method described in Example 1 of the patent document with announcement number CN114769600B and titled "A Si-containing high entropy alloy powder and preparation method thereof".

[0048] Comparative Example 2 A high entropy alloy powder, which is different from Example 3 in that the Ni raw material in this comparative example is single-element nickel powder.

[0049] Comparative Example 3 A high entropy alloy powder, which is different from Example 3 in that the Cr raw material in this comparative example is single-element chromium powder.

[0050] Comparative Example 4 A high entropy alloy powder, which is different from Example 3 in that the Nb raw material in this comparative example is single substance niobium powder.

[0051] Performance testing According to the method specified in GB / T 2975, the high entropy alloys prepared in Examples 1-8 and Comparative Examples 1-4 were made into rod samples, and the cross-sectional diameter of the rods was 5 mm. Then, the properties of the alloy rods were tested according to the method specified in GB / T 228.1-2021. The test results are shown in Table 2.

[0052] Table 2 Test results of Examples 1-8 and Comparative Examples 1-4

[0053] The tensile strength of the rods prepared from the high entropy alloy powders of Examples 1-7 is maintained above 1400 MPa, and the specified plastic extension strength is maintained above 1100 MPa. It can be seen that the strength performance of the samples of Examples 1-7 is significantly better than that of Comparative Examples 1-4. This shows that the hollow nano Ni powder, hollow nano Cr powder and nano twin niobium flakes prepared by the method of the present application as the main metal raw materials can significantly improve the strength of the high entropy alloy.

[0054] Comparative Example 1 uses a high entropy alloy powder prepared by a method in another patent document, and its strength is much lower than that of the embodiment, indicating that the method of the present application has significant advantages in improving strength. Comparative Examples 2-4 respectively replaced the hollow nano Ni powder, hollow nano Cr powder and nano twin niobium sheet in Example 3 with elemental nickel powder, elemental chromium powder and elemental niobium powder, and the results showed that the strength of the final high entropy alloy powder decreased. This further verifies the importance of hollow nanostructures and nano twin structures in improving the strength of high entropy alloys. The tensile strength and specified plastic extension strength of Example 8 are significantly lower than those of other embodiments, because the electrodeposition parameters when preparing nano twin niobium sheets in Preparation Example 10 are not conducive to the formation of an effective nano twin structure, thereby affecting the strength of the alloy.

[0055] The elongation after fracture and the cross-sectional shrinkage of Examples 1-8 are higher than those of Comparative Examples 1-4, indicating that the use of hollow nanopowder and nanotwin niobium flakes can improve the toughness of high entropy alloys. The toughness of Comparative Example 1 is the worst, which corresponds to its lower strength, indicating that hollow nano Ni powder, hollow nano Cr powder and nanotwin niobium flakes as main metal raw materials have a certain promoting effect on the strength and toughness of high entropy alloys. Although the toughness of Comparative Examples 2-4 is higher than that of Comparative Example 1, it is still lower than that of the embodiment, indicating that the replacement of hollow nanopowder and nanotwin niobium flakes with single powder will lead to a decrease in the toughness of high entropy alloys.

[0056] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high entropy alloy powder, characterized in that: The elements by mass percentage include: Ni: 50%-55%; Nb: 4.75%-5.5%; Mo: 2.8%-3.3%; Cr: 17%-21%; Al: 0.2%-0.8%; Ti: 0.65%-1.15%; Co: ≤1.00%; B: ≤0.006%; Si: ≤0.35%; Mn: ≤0.35%; Cu: ≤0.3%; Mg: ≤0.01%; C: ≤0.08%; S: ≤0.015%; P: ≤0.015%; the balance is iron; The Ni raw material is hollow nano Ni powder, the Cr raw material is hollow nano Cr powder, and the Nb raw material is nano twin niobium flakes.

2. A high entropy alloy powder according to claim 1, characterized in that: The hollow nano Ni powder is prepared by the following method: A. Use nickel powder as evaporation source material, place the nickel powder in the evaporation chamber of the PVD equipment, and place the nano-alumina powder in the deposition chamber of the PVD equipment; B. After evacuating the PVD equipment, deposition is performed. During the deposition process, the evaporation temperature is controlled at 1500-1550°C and the deposition time is 2-3h. After the deposition is completed, a nano-nickel ball / aluminum oxide complex is obtained; the nano-nickel ball / aluminum oxide complex is added to a sodium hydroxide aqueous solution, and after magnetic stirring at 50-70°C for 1-2h, hollow nano-Ni powder is obtained by filtration, washing and drying.

3. A high entropy alloy powder according to claim 2, characterized in that: The purity of the nano alumina powder in step A is greater than 99.9%, and the average particle size of the nano alumina powder is 10-40 nm.

4. The high entropy alloy powder according to claim 1, characterized in that: The hollow nano Cr powder is prepared by the following method: (1) Using chromium powder as an evaporation source material, placing the chromium powder in an evaporation chamber of a PVD device, and placing nano-silicon dioxide powder in a deposition chamber of the PVD device; (2) The PVD equipment is evacuated and then deposited. During the deposition process, the evaporation temperature is controlled at 1850-1900°C and the deposition time is 3-4 hours. After the deposition is completed, a nano-chromium ball / silicon dioxide composite is obtained; the nano-chromium ball / silicon carbide composite is added to a hydrofluoric acid solution, and after magnetic stirring at 40-50°C for 1-2 hours, the hollow nano-Cr powder is obtained by filtration, washing and drying.

5. A high entropy alloy powder according to claim 4, characterized in that: The purity of the nano-silicon dioxide powder in step (1) is greater than 99.5%, and the average particle size of the nano-silicon dioxide powder is 10-50 nm.

6. The high entropy alloy powder according to claim 1, characterized in that: The nano twinned niobium sheet is prepared by the following method: The niobium salt and sulfuric acid solution are dissolved in deionized water to prepare an electrolyte. A niobium plate is selected as an anode and a stainless steel plate is selected as a cathode. The electrodes are placed in the electrolyte for electrodeposition. After the electrodeposition is completed, the stainless steel plate is taken out and the residual electrolyte on the surface is rinsed off with deionized water. Under the protection of inert gas, after annealing, the niobium layer is separated from the stainless steel plate to obtain a nano-twinned niobium sheet.

7. A high entropy alloy powder according to claim 6, characterized in that: The niobium salt is a niobium oxalate solution, and the volume ratio of the niobium oxalate solution, the sulfuric acid solution and deionized water is 1:1:(2-3.5).

8. The high entropy alloy powder according to claim 6, characterized in that: The electrodeposition treatment parameters are: pulse current density is 10-50mA / cm², on / off time ratio is 1:(5-10), electrolyte temperature is controlled at 30-60℃, magnetic stirring is performed at a stirring speed of 200-500rpm, and electrodeposition time is 5-8h.

9. A method for preparing a high entropy alloy powder according to any one of claims 1 to 8, characterized in that: The steps include: S1. Prepare raw materials corresponding to each element according to the ratio, wherein the Ni raw material is hollow nano Ni powder, the Cr raw material is hollow nano Cr powder, the Nb raw material is nano twin niobium flakes, and the remaining elements are prepared in the form of single substance and / or alloy; S2. Mix the raw materials and smelt them under a protective atmosphere to obtain a molten alloy. Use an atomizing device to atomize the molten alloy. Use argon gas as the atomizing gas. After the atomization is completed, cool the molten alloy and wash and sieve it to obtain a high entropy alloy powder.

10. The method for preparing a high entropy alloy powder according to claim 9, characterized in that: During the atomization treatment in S2, the atomization gas pressure is 3-6MPa and the atomization temperature is 1200-1500°C.

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