A high-strength rhenium alloy material and a method for manufacturing the same

Abstract

This invention belongs to the technical field of rhenium alloy materials, specifically relating to a high-strength rhenium alloy material and its preparation method. The rhenium alloy material is composed of the following raw materials in the indicated mass percentages: molybdenum 12-24 wt%, niobium 6-9 wt%, cobalt 2-5 wt%, tungsten 1-3 wt%, modified tantalum carbide 0.5-1.2 wt%, high-entropy rare earth elements 3-6 wt%, with the balance being rhenium and other unavoidable impurities. The modified tantalum carbide is prepared by the following process: tantalum chloride, zirconium oxychloride, and phenolic resin are added to a mixed solution of acetylacetone and n-butanol, stirred for 1-2 h under heating conditions, ammonia is added dropwise, and stirring continues for 0.5-1 h. After drying, a precursor is obtained; the precursor is calcined and cooled to obtain modified tantalum carbide. The rhenium alloy prepared by this invention exhibits high hardness, good bending strength, and excellent high-temperature mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of rhenium alloy material technology, specifically relating to a high-strength rhenium alloy material and its preparation method. Background Technology

[0002] Rhenium is a rare metal with extremely low abundance in the Earth's crust. However, rhenium and its alloys possess high strength, high hardness, good plasticity, and excellent mechanical stability. Elemental rhenium has a melting point as high as 3180 °C, second only to tungsten among elemental metals. Therefore, rhenium alloys maintain high strength, plasticity, impact resistance, and creep resistance even at high temperatures. Furthermore, rhenium alloys have a low and stable coefficient of thermal expansion, resulting in minimal dimensional changes at high temperatures. They also possess high thermal conductivity, allowing for rapid heat transfer from high-temperature regions and preventing localized overheating. Therefore, the applications of rhenium alloys are concentrated in scenarios with extreme high-temperature performance requirements, such as turbine blades, combustion chambers and nozzles of aerospace engines, and structural components of high-temperature reactors, making them strategic materials for high-end equipment.

[0003] Due to rhenium's extremely high melting point, powder metallurgy is the mainstream process for preparing rhenium alloys. Solid-state sintering achieves bonding between high-melting-point particles, allowing for precise control of alloy composition and microstructure, thus effectively solving the problem of difficult rhenium alloy forming. However, directly mixing and sintering pure rhenium powder with other metals and reinforcing phase powders presents several problems: rhenium resources are scarce and mostly found in molybdenum and copper ores, making extraction difficult and resulting in high rhenium alloy costs; rhenium powder is difficult to process, often exhibiting irregular shapes and poor flowability, making it difficult to control mixing uniformity and affecting alloy sintering quality; sintered rhenium alloys tend to have coarse grains and insufficient room-temperature plasticity, which is detrimental to subsequent processing and applications.

[0004] Currently, methods such as powder raw material pretreatment, optimized metallurgical forming processes, and improved sintering and heat treatment regimes have been used to improve the microstructure and properties of rhenium alloys to a certain extent. However, facing the increasingly demanding performance requirements under extreme conditions such as aerospace and high-temperature reactors, existing rhenium alloys still need further breakthroughs in mechanical and high-temperature properties to drive the continued development of rhenium alloys and expand their high-end applications. Summary of the Invention

[0005] The primary objective of this invention is to provide a high-strength rhenium alloy material, which has high hardness, good bending strength, and excellent high-temperature mechanical properties.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned high-strength rhenium alloy material.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A high-strength rhenium alloy material is composed of the following raw materials in the following mass percentages: molybdenum 12-24 wt%, niobium 6-9 wt%, cobalt 2-5 wt%, tungsten 1-3 wt%, modified tantalum carbide 0.5-1.2 wt%, high-entropy rare earth 3-6 wt%, with the balance being rhenium and other unavoidable impurities;

[0009] The modified tantalum carbide is prepared by the following process:

[0010] (1) Add tantalum chloride, zirconium oxychloride and phenolic resin to a mixed solution of acetylacetone and n-butanol, stir for 1-2 h under heating, add ammonia dropwise and continue stirring for 0.5-1 h, and dry to obtain the precursor;

[0011] (2) The precursor was calcined and cooled to obtain modified tantalum carbide.

[0012] Further, in step (1), the ratio of tantalum chloride, zirconium oxychloride, phenolic resin, acetylacetone, n-butanol and ammonia is 1 g: (0.05-0.1) g: (0.2-0.4) g: (5-10) mL: (40-60) mL: (5-10) mL; the heating temperature is 60-80 ℃; and the mass concentration of ammonia is 25-28%.

[0013] Furthermore, the calcination temperature in step (2) is 1450-1550 ℃ and the time is 2-4 h.

[0014] Furthermore, the high-entropy rare earth element is prepared by the following process:

[0015] La, Ce, Pr, Y and Gd are smelted in an argon atmosphere and cooled to obtain a master alloy ingot; the master alloy ingot is then melted and atomized to obtain the high-entropy rare earth.

[0016] Furthermore, the molar ratio of La, Ce, Pr, Y to Gd is (1-2):(1-2):(1-2):(1-2):1.

[0017] Furthermore, the gas pressure for gas atomization is 2-4 MPa, and the gas is argon.

[0018] The above-mentioned method for preparing high-strength rhenium alloy materials includes the following steps:

[0019] (a) Mix the raw materials, add ethanol and ball mill, dry and grind to obtain a mixture;

[0020] (b) The mixture is molded into a compact;

[0021] (c) The pressed blank is pre-sintered and then sintered at high temperature, and then cooled to obtain the rhenium alloy material.

[0022] Further, in step (a), the mass ratio of ethanol to the total of all raw materials is 1:5-8; the ball milling time is 20-30 h; and the grinding time is 0.5-2 h.

[0023] Furthermore, the compression molding pressure in step (b) is 150-200 MPa, and the compression time is 2-5 min.

[0024] Further, in step (c), the pre-sintering temperature is 900-1200 ℃ and the time is 2-4 h; the high-temperature sintering temperature is 2000-2200 ℃ and the time is 5-12 h.

[0025] The beneficial technical effects of this invention are as follows:

[0026] 1. This invention adds zirconium-doped modified tantalum carbide as a reinforcing phase to rhenium alloys, thereby improving the high-temperature strength of the alloys. Tantalum carbide possesses high strength and hardness, and the zirconium doping modification alleviates its brittleness, giving it both strength and toughness. Dispersed in the rhenium alloy matrix, it can form a pinning effect, hindering dislocation and grain boundary migration, and improving the strength and hardness of the alloy through a dispersion strengthening mechanism. Tantalum carbide also has an extremely high melting point, maintaining a complete crystal structure even in ultra-high temperature environments, and is not prone to melting or softening. It can still play a pinning strengthening role at high temperatures, and can also inhibit grain growth and microstructure coarsening of rhenium alloys at high temperatures. Furthermore, zirconium doping can improve the sintering activity and high-temperature oxidation resistance of tantalum carbide, enhance its stability at high temperatures, improve the sintering quality of rhenium alloys, and ensure the high-temperature strength of the alloys.

[0027] 2. This invention adds high-entropy rare earth elements as a binder phase to rhenium alloys, which can effectively improve the strength and hardness of the alloys. High-entropy rare earth elements have a high-entropy effect, which can reduce the interfacial energy between the matrix and the reinforcing phase, improve interfacial wettability, and increase sintering density; at the same time, high-entropy rare earth elements have a retarded diffusion effect, which can inhibit the diffusion of the matrix phase to the binder phase, avoid abnormal grain growth, inhibit the formation of harmful phases, and improve the strength and hardness of the alloy; and rare earth elements have extremely strong oxygen affinity, which can adsorb impurities, purify grain boundaries, reduce grain boundary embrittlement, and improve the overall mechanical properties of the alloy. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the modified tantalum carbide prepared in Example 1 of the present invention;

[0029] Figure 2 This is a scanning electron microscope image of the high-entropy rare earth element obtained in Example 1 of the present invention. Detailed Implementation

[0030] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0031] (I) Implementation Examples

[0032] Example 1

[0033] Example 1 provides a high-strength rhenium alloy material, which is composed of the following raw materials in the following mass percentages: molybdenum 19 wt%, niobium 7 wt%, cobalt 3 wt%, tungsten 2 wt%, modified tantalum carbide 0.8 wt%, high-entropy rare earth 4 wt%, with the balance being rhenium and other unavoidable impurities.

[0034] The modified tantalum carbide is prepared by the following process:

[0035] (1) Tantalum chloride, zirconium oxychloride, phenolic resin, acetylacetone, n-butanol and ammonia were added to a mixed solution of acetylacetone and n-butanol according to the ratio of 1 g: 0.08 g: 0.3 g: 8 mL: 50 mL: 8 mL. The mixture was stirred at 70 °C for 1 h, and then 27% ammonia was added dropwise and stirred for another 0.8 h. After drying, the precursor was obtained.

[0036] (2) The precursor was calcined at 1500 °C for 3 h, and then cooled to room temperature in the furnace to obtain modified tantalum carbide; the scanning electron microscope image of the modified tantalum carbide is shown below. Figure 1 As shown.

[0037] The high-entropy rare earth element is prepared by the following process:

[0038] According to the molar ratio of La, Ce, Pr, Y, and Gd of 1.5:1.5:1.5:1.5:1, La, Ce, Pr, Y, and Gd were placed in a melting furnace and melted uniformly under an argon atmosphere. After cooling, a master alloy ingot was obtained. The master alloy ingot was melted under an argon atmosphere and transferred to the insulation bag of a gas atomization device. After introducing argon gas, the gas atomization gas pressure was set to 3 MPa, and the gas atomization device was started. After collection, high-entropy rare earth elements were obtained. The scanning electron microscope image of the high-entropy rare earth elements is shown below. Figure 2 As shown.

[0039] This embodiment also provides a method for preparing the above-mentioned high-strength rhenium alloy material, the specific steps of which are as follows:

[0040] (a) Weigh the above rhenium alloy raw materials according to the mass ratio of ethanol to total rhenium alloy raw materials of 1:6 and mix them evenly. After adding ethanol, ball mill the mixture for 26 h, dry it, and grind it for 1 h under a nitrogen atmosphere to obtain the mixture.

[0041] (b) The mixture is loaded into a mold and pressed under a pressure of 180 MPa for 3 min to obtain a compact;

[0042] (c) The pressed billet is placed in a sintering furnace and pre-sintered at 1100 °C for 3 h, and then sintered at 2100 °C for 8 h. After cooling, rhenium alloy material is obtained.

[0043] Example 2

[0044] Example 2 provides a high-strength rhenium alloy material, which is composed of the following raw materials in the following mass percentages: 12 wt% molybdenum, 6 wt% niobium, 2 wt% cobalt, 1 wt% tungsten, 0.5 wt% modified tantalum carbide, 3 wt% high-entropy rare earth, with the balance being rhenium and other unavoidable impurities.

[0045] The modified tantalum carbide is prepared by the following process:

[0046] (1) Tantalum chloride, zirconium oxychloride, phenolic resin, acetylacetone, n-butanol and ammonia were added to a mixed solution of acetylacetone and n-butanol according to the ratio of 1 g: 0.05 g: 0.2 g: 5 mL: 40 mL: 5 mL. The mixture was stirred at 60 °C for 1 h, and then 25% ammonia was added dropwise and stirred for another 0.5 h. After drying, the precursor was obtained.

[0047] (2) The precursor was calcined at 1450 °C for 2 h and then cooled to room temperature in the furnace to obtain modified tantalum carbide.

[0048] The high-entropy rare earth element is prepared by the following process:

[0049] According to the molar ratio of La, Ce, Pr, Y and Gd of 1:1:1:1:1, La, Ce, Pr, Y and Gd are placed in a melting furnace and melted uniformly under an argon atmosphere. After cooling, a master alloy ingot is obtained. The master alloy ingot is melted under an argon atmosphere and transferred to the heat preservation bag of a gas atomization device. After argon is introduced, the gas atomization gas pressure is set to 2 MPa, the gas atomization device is started, and high entropy rare earth is obtained after collection.

[0050] This embodiment also provides a method for preparing the above-mentioned high-strength rhenium alloy material, the specific steps of which are as follows:

[0051] (a) Weigh the above rhenium alloy raw materials according to the mass ratio of ethanol to total rhenium alloy raw materials of 1:5 and mix them evenly. After adding ethanol, ball mill the mixture for 20 h, dry it and grind it for 0.5 h under nitrogen atmosphere to obtain the mixture.

[0052] (b) The mixture is loaded into a mold and pressed under a pressure of 150 MPa for 2 min to obtain a compact;

[0053] (c) The pressed billet is placed in a sintering furnace and pre-sintered at 900 °C for 2 h, and then sintered at 2000 °C for 5 h. After cooling, rhenium alloy material is obtained.

[0054] Example 3

[0055] Example 3 provides a high-strength rhenium alloy material, which is composed of the following raw materials in the following mass percentages: 24 wt% molybdenum, 9 wt% niobium, 5 wt% cobalt, 3 wt% tungsten, 1.2 wt% modified tantalum carbide, 6 wt% high-entropy rare earth, with the balance being rhenium and other unavoidable impurities.

[0056] The modified tantalum carbide is prepared by the following process:

[0057] (1) Tantalum chloride, zirconium oxychloride, phenolic resin, acetylacetone, n-butanol and ammonia were added to a mixed solution of acetylacetone and n-butanol according to the ratio of 1 g: 0.1 g: 0.4 g: 10 mL: 60 mL: 10 mL. The mixture was stirred at 80 °C for 2 h, and then 28% ammonia was added dropwise and stirred for another 1 h. After drying, the precursor was obtained.

[0058] (2) The precursor was calcined at 1550 °C for 4 h and then cooled to room temperature in the furnace to obtain modified tantalum carbide.

[0059] The high-entropy rare earth element is prepared by the following process:

[0060] According to the molar ratio of La, Ce, Pr, Y and Gd of 2:2:2:2:1, La, Ce, Pr, Y and Gd are placed in a melting furnace and melted uniformly under an argon atmosphere. After cooling, a master alloy ingot is obtained. The master alloy ingot is melted under an argon atmosphere and transferred to the heat preservation bag of a gas atomization device. After argon is introduced, the gas atomization gas pressure is set to 4MPa, the gas atomization device is started, and high entropy rare earth is obtained after collection.

[0061] This embodiment also provides a method for preparing the above-mentioned high-strength rhenium alloy material, the specific steps of which are as follows:

[0062] (a) Weigh the above rhenium alloy raw materials according to the mass ratio of ethanol to rhenium alloy raw materials of 1:8 and mix them evenly. After adding ethanol, ball mill the mixture for 30 h, dry it and grind it for 2 h under nitrogen atmosphere to obtain the mixture.

[0063] (b) The mixture is loaded into a mold and pressed under a pressure of 200 MPa for 5 min to obtain a compact;

[0064] (c) The compact is placed in a sintering furnace and pre-sintered at 1200 °C for 4 h, and then sintered at 2200 °C for 12 h. After cooling, rhenium alloy material is obtained.

[0065] (ii) Comparative Example

[0066] Comparative Example 1

[0067] Comparative Example 1 is basically the same as Example 1, except that the modified tantalum carbide in Example 1 is omitted.

[0068] Comparative Example 2

[0069] Comparative Example 2 is basically the same as Example 1, except that the modified tantalum carbide in Example 1 is replaced with tantalum carbide.

[0070] Comparative Example 3

[0071] Comparative Example 3 is basically the same as Example 1, except that the high-entropy rare earth in Example 1 is replaced with a La / Ce mixture, the amount of the mixture is the same as that of the high-entropy rare earth, and the molar ratio of La to Ce is the same as that of Example 1.

[0072] (III) Test Examples

[0073] The rhenium alloy materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests.

[0074] Hardness test: The hardness of the rhenium alloy materials in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 4340.1-2024 "Metallic materials Vickers hardness test - Part 1: Test method". The results are shown in Table 1.

[0075] High-temperature yield strength test: The rhenium alloy materials of Examples 1-3 and Comparative Examples 1-3 were tested at 1000℃ in accordance with GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature". The results are shown in Table 1.

[0076] Bending strength test: The bending strength of rhenium alloy materials in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 3851-2015 "Determination of transverse fracture strength of cemented carbide". The results are shown in Table 1.

[0077] Table 1. Test results of hardness, high-temperature yield strength and flexural strength of rhenium alloy materials

[0078]

[0079] As shown in Table 1, the rhenium alloy materials prepared in Examples 1-3 of this invention have high hardness, good bending strength, and excellent high-temperature mechanical properties.

[0080] Compared to Example 1, Comparative Example 1 omits the modified tantalum carbide in Example 1, and Comparative Example 2 replaces the modified tantalum carbide in Example 1 with tantalum carbide. The hardness, high-temperature yield strength and bending strength of Comparative Examples 1-2 all decreased to varying degrees. This indicates that adding modified tantalum carbide to rhenium alloy materials can improve hardness and bending strength, and significantly affect high-temperature yield strength. Specifically, the analysis is as follows: Tantalum carbide has high strength and high hardness. The doping modification of zirconium alleviates the brittleness of tantalum carbide, giving it both strength and toughness. When dispersed in the rhenium alloy matrix, it can form a pinning effect, hindering dislocation and grain boundary migration, and improving the strength and hardness of the alloy through a dispersion strengthening mechanism. Tantalum carbide also has an extremely high melting point and can maintain a complete crystal structure even in ultra-high temperature environments, making it difficult to melt or soften. It can still play a pinning strengthening role at high temperatures and can also inhibit grain growth and microstructure coarsening of rhenium alloy at high temperatures. Furthermore, zirconium doping can improve the sintering activity and high-temperature oxidation resistance of tantalum carbide, enhance the stability of tantalum carbide at high temperatures, improve the sintering quality of rhenium alloy, and ensure the high-temperature strength of the alloy.

[0081] Compared to Example 1, Comparative Example 3 replaced the high-entropy rare earth element in Example 1 with a mixture of lanthanum and cerium, resulting in a significant decrease in hardness and flexural strength. This indicates that adding high-entropy rare earth elements to rhenium alloy materials can significantly improve hardness and flexural strength. Specifically, high-entropy rare earth elements exhibit a high-entropy effect, reducing the interfacial energy between the matrix and reinforcing phases, improving interfacial wettability, and increasing sintering density. Simultaneously, high-entropy rare earth elements have a retarded diffusion effect, inhibiting the diffusion of the matrix phase towards the binder phase, preventing abnormal grain growth, suppressing the formation of harmful phases, and improving alloy strength and hardness. Furthermore, rare earth elements have extremely strong oxygen affinity, enabling them to adsorb impurities, purify grain boundaries, reduce grain boundary embrittlement, and improve the overall mechanical properties of the alloy.

[0082] 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. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A high-strength rhenium alloy material, characterized in that, It is composed of the following raw materials in the following mass percentages: molybdenum 12-24 wt%, niobium 6-9 wt%, cobalt 2-5 wt%, tungsten 1-3 wt%, modified tantalum carbide 0.5-1.2 wt%, high-entropy rare earth 3-6 wt%, with the balance being rhenium and other unavoidable impurities; The modified tantalum carbide is prepared by the following process: (1) Add tantalum chloride, zirconium oxychloride and phenolic resin to a mixed solution of acetylacetone and n-butanol, stir for 1-2 h under heating, add ammonia dropwise and continue stirring for 0.5-1 h, and dry to obtain the precursor; (2) The precursor was calcined and cooled to obtain modified tantalum carbide; The high-entropy rare earth element is prepared by the following process: La, Ce, Pr, Y and Gd are melted in an argon atmosphere and cooled to obtain a master alloy ingot; the master alloy ingot is then melted and atomized to obtain the high-entropy rare earth. In step (1), the ratio of tantalum chloride, zirconium oxychloride, phenolic resin, acetylacetone, n-butanol, and ammonia is 1 g: (0.05-0.1) g: (0.2-0.4) g: (5-10) mL: (40-60) mL: (5-10) mL; the heating temperature is 60-80 ℃; and the mass concentration of ammonia is 25-28%.

2. The high-strength rhenium alloy material according to claim 1, characterized in that, The calcination temperature in step (2) is 1450-1550 ℃ and the time is 2-4 h.

3. The high-strength rhenium alloy material according to claim 1, characterized in that, The molar ratio of La, Ce, Pr, Y and Gd is (1-2):(1-2):(1-2):(1-2):

1.

4. The high-strength rhenium alloy material according to claim 1, characterized in that, The gas pressure for atomization is 2-4 MPa, and the gas is argon.

5. A method for preparing a high-strength rhenium alloy material according to any one of claims 1-4, characterized in that, Includes the following steps: (a) Mix the raw materials, add ethanol and ball mill, dry and grind to obtain a mixture; (b) The mixture is molded into a compact; (c) The pressed blank is pre-sintered and then sintered at high temperature, and then cooled to obtain the rhenium alloy material.

6. The method for preparing high-strength rhenium alloy material according to claim 5, characterized in that, In step (a), the mass ratio of ethanol to the total of all raw materials is 1:5-8; the ball milling time is 20-30 h; and the grinding time is 0.5-2 h.

7. The method for preparing high-strength rhenium alloy material according to claim 5, characterized in that, The compression molding pressure in step (b) is 150-200 MPa, and the compression time is 2-5 min.

8. The method for preparing high-strength rhenium alloy material according to claim 5, characterized in that, The pre-sintering temperature in step (c) is 900-1200 ℃ and the time is 2-4 h; the high-temperature sintering temperature is 2000-2200 ℃ and the time is 5-12 h.

Images