Method for preparing Mo-Nb solid solution alloy by prefabricating Mo-Nb solid solution seed crystal
By prefabing Mo-Nb solid solution seed crystals before sintering, and using mechanical ball milling technology to promote the diffusion of Mo and Nb, the problems of poor performance of Mo-Nb alloys and high energy consumption in the prior art are solved, and the problem of mechanical alloying method is achieved. Efficient and environmentally friendly preparation of Mo-Nb solid solution alloy.
Patent Information
- Application Number
- CN202411525321.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2025-02-21
AI Technical Summary
In the preparation of Mo-Nb solid solution alloys, the surface tension in the melting zone is sensitive to surface impurities and temperature gradients, resulting in poor crystal growth and poor performance. The mechanical alloying method consumes a large energy and costs, and is prone to over-the-counter. Fine alloy powder explodes.
Before sintering, Mo-Nb solid-solution seeds are prefabricated by medium-speed, short-term mechanical ball milling process. Prefabricated seeds are used as diffusion medium to promote the mutual diffusion of Mo and Nb, achieve complete alloying, and reduce the sintering temperature.
The complete alloying of Mo-Nb solution alloy is achieved, which reduces the sintering temperature and improves the mechanical properties of the alloy. The process is energy-saving and environmentally friendly, and has high safety.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of refractory metal materials and powder metallurgy, and in particular relates to a method for preparing a Mo-Nb solid solution alloy by prefabricating Mo-Nb solid solution seeds. Background Art
[0002] Mo-Nb refractory alloys have excellent mechanical properties such as high melting point, high hardness, and low high-temperature creep, which makes them show great potential in high-temperature fields such as aerospace, biomedicine, and mechanical manufacturing. However, the current Mo-Nb alloys on the market are limited in their application due to their poor high-temperature stability and other shortcomings. Therefore, people are committed to improving the mechanical properties of Mo-Nb alloys to meet the needs of industrial development. At present, there are many methods for preparing Mo-Nb solid solution alloys at home and abroad, such as electron beam melting, plasma melting, and powder metallurgy. Since the last century, people have used electron beam melting and plasma melting to develop Mo-Nb solid solution alloys and tried to apply them to space technology, but Patent 201911032007: "A method for preparing a single crystal rod of Mo-Nb-W-Zr alloy" mentioned that due to the high sensitivity of the surface tension of the melt zone of electron beam melting and plasma melting to surface impurities and temperature gradients, it is not conducive to the growth of Mo-Nb crystals. Therefore, the obtained Mo-Nb alloy has poor performance and cannot meet the needs of industry development.
[0003] At present, powder metallurgy is one of the common processes for preparing Mo-Nb refractory alloys. Its preparation process requires pre-mixing of alloy powders, followed by pressing and sintering of the well-mixed powders to obtain the final alloy product. Among them, the methods for preparing mixed powders include mechanical alloying, liquid-solid doping, and liquid-liquid doping (sol-gel method, coprecipitation method). Among them, mechanical alloying has the advantages of simple preparation process, low requirements for raw materials and equipment, high production efficiency, less waste gas and waste, less environmental pollution and short process flow compared to solid-liquid doping and liquid-liquid doping. Mechanical alloying is a complex physical and chemical process that allows the powder to undergo multiple deformations and fractures to ultimately achieve alloying at the atomic level between elements. In particular, the particle size, morphology and composition of the final mixed powder determine the density and mechanical properties of the sample after powder metallurgy sintering. This technology not only improves the contact range and rotation speed of the grinding body and the material, but also solves the problems of inclusion generation and limited application range in traditional powder making methods. In addition, the mechanical alloying method can also achieve complete alloying of powders at room temperature through high-speed ball milling, thereby obtaining an alloy that is completely solid-solution after sintering. For example, the predecessors used mechanical alloying to prepare a high-performance NbMoTaWVCr high-entropy alloy with complete solid solution. However, the mechanical alloying method usually requires extremely high rotation speed and long-term ball milling to obtain fully alloyed powders. This process is not only energy-intensive and has high production costs, but also prone to explosions of ultrafine alloy powders. Therefore, the preparation method of directly obtaining fully alloyed powders by mechanical alloying also requires additional improvement of the safety protection level of production equipment, which ultimately leads to a sharp increase in production costs. Therefore, the process of preparing fully alloyed powders by mechanical alloying has not been widely used. Therefore, it is necessary to develop other efficient, low-cost, energy-saving, environmentally friendly and safe methods to prepare Mo-Nb solid solution alloys.
[0004] The present invention discovers for the first time that prefabricated Mo-Nb solid solution seeds before sintering can promote the complete alloying process of the Mo-Nb solid solution after sintering, which can effectively promote the sintering process of the Mo-Nb solid solution with a single-phase BCC structure. The viewpoint of the present invention is obviously different from the purpose of the traditional mechanical alloying process, that is, the viewpoint that a high-speed and long-time mechanical ball milling process is required to achieve complete alloying of the powder in order to obtain a Mo-Nb solid solution alloy. The specific mechanism is that the present invention uses a medium-speed and short-time mechanical ball milling process to prefabricate Mo-Nb solid solution seeds before sintering, which acts as a "diffusion medium" during the sintering process, helps the mutual diffusion of Mo and Nb, and thus promotes the formation of a fully alloyed MoNb solid solution; in addition, due to the lattice distortion caused by the partial solid solution effect, the powder can be placed in a high-energy activation state, which promotes the sintering process of the Mo-Nb solid solution with a single-phase BCC structure. At present, there is no research on mechanical alloying to preform Mo-Nb solid solution seeds in the powder before sintering to promote the complete solid solution sintering of Mo-Nb alloy. Therefore, the present invention is the first to actively preform Mo-Nb solid solution seeds in the mixed powder to ensure complete alloying after sintering, thereby obtaining an energy-saving and environmentally friendly Mo-Nb solid solution alloy with excellent performance. Summary of the invention
[0005] The technical problem to be solved by the present invention is to provide a method for preparing Mo-Nb alloy by prefabricating Mo-Nb solid solution seeds in view of the deficiencies of the above-mentioned prior art. The present invention prefabricates Mo-Nb solid solution seeds in the mixed powder before sintering by adjusting the rotation speed of the grinding balls in the high-energy ball mill. Compared with the traditional mechanical alloying method, the method of preparing Mo-Nb solid solution alloy by prefabricating Mo-Nb solid solution seeds is energy-saving, efficient, environmentally friendly, and safe. It does not require obtaining a completely alloyed powder, but through the strategy of actively prefabricating Mo-Nb solid solution seeds, it can achieve the purpose of lowering the sintering temperature of the Mo-Nb solid solution alloy, obtaining an alloy in which Mo-Nb is completely dissolved after sintering, and improving the performance of the Mo-Nb solid solution alloy. The preparation method of prefabricated Mo-Nb solid solution seeds proposed in the present invention is of great significance to the research and preparation of refractory alloys in the future.
[0006] A method for preparing a Mo-Nb solid solution alloy by prefabricating Mo-Nb solid solution seeds comprises the following steps:
[0007] (1) Weighing materials: Under an argon atmosphere, weigh the raw materials of molybdenum powder and niobium powder according to the proportion in a glove box; select the number of small balls and large balls, and use bolts to fix the vacuum sleeve and lock the ball mill;
[0008] (2) Mixing: The weighed powders are ball-milled and mixed in a planetary ball mill to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds;
[0009] (3) Sintering: Sintering the Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds under vacuum to obtain a Mo-Nb solid solution alloy with a dense structure;
[0010] (4) Treatment: The Mo-Nb solid solution alloy is subjected to grinding, polishing and other processing.
[0011] Preferably, in the weighing process of step (1), the raw materials of molybdenum powder and niobium powder are weighed in a glove box according to a molar ratio of molybdenum to niobium of (1-5):1; the mass ratio of ball to material is (10-30):1; the mass ratio of large ball to small ball is 1:(2-5), and the whole process of canning is operated under an argon atmosphere to ensure argon gas protection in the ball milling jar to avoid the formation of oxides before and after ball milling;
[0012] Preferably, in step (2), the mixing process is as follows: the prepared raw materials are mixed in a planetary ball mill at a ball milling speed of 200-500 r / min for 5-40 hours to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds; alcohol is further used as a solvent for ball milling.
[0013] Preferably, the sintering process of step (3) is as follows: the Mo-Nb solid solution seed powder prefabricated by ball milling is hot-pressed and sintered under vacuum at 1400-1700° C. for 5-30 min at a pressure of 30-80 MPa, and preferably the heating rate is 50-300° C. / min to obtain a Mo-Nb solid solution alloy material with a dense and uniform structure;
[0014] Preferably, step (4) comprises the following steps: subjecting the Mo-Nb solid solution alloy to grinding, polishing and other processing.
[0015] The invention is the first to actively preform Mo-Nb solid solution seeds in the mixed powder to achieve complete alloying after sintering, thereby obtaining a Mo-Nb solid solution alloy that is energy-saving, environmentally friendly, safe, and has excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 XRD of high energy ball milled powder and MoNb solid solution alloy after sintering in Examples 1-4.
[0017] Figure 2 SEM and EDS of high-energy ball-milled powders of Examples 1-4.
[0018] Table 1 shows the Vickers hardness test results of Examples 1-4. DETAILED DESCRIPTION
[0019] The present invention will be further described below in conjunction with examples, but the present invention is not limited to the following examples.
[0020] Example 1
[0021] A method for preparing a Mo-Nb solid solution alloy by prefabricating Mo-Nb solid solution seeds is carried out according to the following steps:
[0022] 1) Mixing ingredients: Molybdenum powder and niobium powder are mixed according to the following molar ratio: Mo-Nb molar ratio 1:1;
[0023] 2) Mixing: Mixing the raw materials prepared in step 1) in a planetary ball mill at a speed of 500 r / min for 10 hours to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds;
[0024] In step 2), the production process of obtaining a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds is as follows: elemental molybdenum powder and niobium powder are weighed in a glove box, passed through a closed ball milling jar in the glove box to ensure high-energy ball milling in an oxygen-free environment, and then mechanically alloyed at room temperature to prefabricate Mo-Nb solid solution seeds; then, alcohol is added according to the ratio of the molybdenum-niobium powder to be produced, and ball milling at a corresponding speed is performed, and the molybdenum-niobium powder and alcohol are fully mixed and dissolved; then the mixed molybdenum-niobium powder and alcohol are dried, and finally a powder containing Mo-Nb solid solution seeds is prefabricated.
[0025] 3) Sintering: The raw materials mixed in step 2) are sent to a hot pressing sintering furnace for sintering. The specific process is: sintering and heat preservation at a temperature of 1450° C. for 20 minutes and a pressure of 80 MPa.
[0026] The sintered samples were subjected to XRD, SEM, EDS analysis and Vickers hardness test. The mechanical properties test results of the alloy are listed in Table 1.
[0027] Example 2
[0028] A method for preparing a Mo-Nb alloy by prefabricating Mo-Nb solid solution seeds is carried out according to the following steps:
[0029] 1) Mixing ingredients: Molybdenum powder and niobium powder are mixed according to the following molar ratio: Mo-Nb molar ratio 2:1;
[0030] 2) Mixing: Mixing the raw materials prepared in step 1) in a planetary ball mill at a speed of 400 r / min for 30 hours to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds;
[0031] In step 2), the production process of obtaining a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds is as follows: elemental molybdenum powder and niobium powder are weighed in a glove box, passed through a closed ball milling jar in the glove box to ensure high-energy ball milling in an oxygen-free environment, and then mechanically alloyed at room temperature to prefabricate Mo-Nb solid solution seeds; then, alcohol is added according to the ratio of the molybdenum-niobium powder to be produced, and ball milling at a corresponding speed is performed, and the molybdenum-niobium powder and alcohol are fully mixed and dissolved; then the mixed molybdenum-niobium powder and alcohol are dried, and finally a powder containing Mo-Nb solid solution seeds is prefabricated.
[0032] 3) Sintering: The raw materials mixed in step 2) are sent to a hot pressing sintering furnace for sintering. The specific process is: sintering and heat preservation for 15 minutes at a temperature of 1500° C. and a pressure of 70 MPa.
[0033] The sintered samples were subjected to XRD, SEM, EDS analysis and Vickers hardness test. The mechanical properties test results of the alloy are listed in Table 1.
[0034] Example 3
[0035] A method for preparing a Mo-Nb alloy by prefabricating Mo-Nb solid solution seeds is carried out according to the following steps:
[0036] 1) Mixing ingredients: Molybdenum powder and niobium powder are mixed according to the following molar ratio: Mo-Nb molar ratio 2:1;
[0037] 2) Mixing: Mixing the raw materials prepared in step 1) in a planetary ball mill at a speed of 300 r / min for 20 hours to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds;
[0038] In step 2), the production process of obtaining a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds is as follows: elemental molybdenum powder and niobium powder are weighed in a glove box, passed through a closed ball mill in the glove box to ensure high-energy ball milling in an oxygen-free environment, and then mechanically alloyed at room temperature to prefabricate Mo-Nb solid solution seeds; then, alcohol is added according to the ratio of the molybdenum-niobium powder to be produced, and the speed ball milling is performed, and the molybdenum-niobium powder and the alcohol are fully mixed and dissolved; then, the mixed molybdenum-niobium powder and the alcohol are dried, and finally, a powder containing Mo-Nb solid solution seeds is prefabricated.
[0039] 3) Sintering: The raw materials mixed in step 2) are sent to a hot pressing sintering furnace for sintering. The specific process is: sintering and heat preservation for 10 minutes at a temperature of 1600° C. and a pressure of 60 MPa.
[0040] The sintered samples were subjected to XRD, SEM, EDS analysis and Vickers hardness test. The mechanical properties test results of the alloy are listed in Table 1.
[0041] Example 4
[0042] A method for preparing a Mo-Nb alloy by prefabricating Mo-Nb solid solution seeds is carried out according to the following steps:
[0043] 1) Mixing ingredients: Molybdenum powder and niobium powder are mixed according to the following molar ratio: Mo-Nb molar ratio 1:1;
[0044] 2) Mixing: Mixing the raw materials prepared in step 1) in a planetary ball mill at a speed of 200 r / min for 40 hours to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds;
[0045] In step 2), the production process of obtaining a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds is as follows: elemental molybdenum powder and niobium powder are weighed in a glove box, passed through a closed ball mill in the glove box to ensure high-energy ball milling in an oxygen-free environment, and then mechanically alloyed at room temperature to prefabricate Mo-Nb solid solution seeds; then, alcohol is added according to the ratio of the molybdenum-niobium powder to be produced, and the speed ball milling is performed, and the molybdenum-niobium powder and the alcohol are fully mixed and dissolved; then, the mixed molybdenum-niobium powder and the alcohol are dried, and finally, a powder containing Mo-Nb solid solution seeds is prefabricated.
[0046] 3) Sintering: The raw materials mixed in step 2) are sent to a hot pressing sintering furnace for sintering. The specific process is: sintering and heat preservation at a temperature of 1700° C. for 5 minutes and a pressure of 50 MPa.
[0047] The sintered samples were subjected to XRD, SEM, EDS analysis and Vickers hardness test. The mechanical properties test results of the alloy are listed in Table 1. Table 1 Mechanical properties test results obtained in each embodiment (five groups of parallel tests)
Claims
1. A method for preparing a Mo-Nb solid solution alloy by prefabricating Mo-Nb solid solution seeds, characterized in that: The following steps are involved: (1) Weighing materials: Under an argon atmosphere, weigh the raw materials of molybdenum powder and niobium powder according to the proportion in a glove box; select the number of small balls and large balls; (2) Mixing: The weighed powders are ball-milled and mixed in a planetary ball mill to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds; (3) Sintering: Sintering the Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds under vacuum to obtain a Mo-Nb solid solution alloy with a dense structure; (4) Treatment: The Mo-Nb solid solution alloy is subjected to grinding, polishing and other processing.
2. The method according to claim 1, characterized in that Step (1) weighing process: weighing the raw materials of molybdenum powder and niobium powder in a glove box according to a molar ratio of molybdenum to niobium of (1-5):1; the mass ratio of ball to material is (10-30):1; the mass ratio of large ball to small ball is 1:(2-5), and the whole process of canning is operated under an argon atmosphere to ensure argon gas protection in the ball milling jar to avoid the generation of oxides before and after ball milling.
3. The method according to claim 1, characterized in that Step (2) mixing process: the prepared raw materials are ball-milled in a planetary ball mill at a ball milling speed of 200-500 r / min for 5-40 hours to obtain a Mo-Nb mixed powder containing prefabricated Mo-Nb solid solution seeds.
4. The method according to claim 3, characterized in that The prepared raw materials are ball-milled and mixed in a planetary ball mill at a ball-milling speed of 400-500 r / min.
5. The method according to claim 1, characterized in that In step (2), alcohol is used as the solvent for ball milling.
6. The method according to claim 1, characterized in that Step (3) Sintering process: hot pressing and sintering the pre-milled Mo-Nb solid solution seed powder at 1400-1700° C. in vacuum, keeping the temperature for 5-30 minutes, and the pressure of 30-80 MPa.
7. The method according to claim 6, characterized in that The heating rate is 50-300°C / min, and a Mo-Nb solid solution alloy material with a dense and uniform organizational structure is obtained.
8. The method according to claim 1, characterized in that Step (2) Step (4) Processing: The Mo-Nb solid solution alloy is subjected to processing such as grinding and polishing.