Method for strengthening NiAl-based composite material through multi-scale double-peak structure

Abstract

The invention discloses a method for strengthening a NiAl-based composite material through a multi-scale double-peak structure, and relates to a preparation method of a nickel-aluminum composite material. The invention aims to solve the problem that the low density, room-temperature plasticity and high-temperature strength of NiAl are difficult to consider in the existing method, so that the application process of NiAl is seriously hindered. The method comprises the following steps: 1, weighing Ni, Al, V, Mo, Zr and B powder; 2, staged ball milling is carried out, and two kinds of mixed metal powder with different particle sizes are screened out; 3, mixing the two mixed metal powders with different particle sizes; 4, applying pre-pressure; 5, heating; and 6, cooling along with the furnace. Two kinds of mixed metal powder particles with different particle sizes are mixed, a double-peak structure continuous staggered distribution structure is obtained at the high temperature through the classical sintering theory, meanwhile, the V (Mo) phase and the ceramic particles are distributed in a material matrix and at the grain boundary, and the obdurability of the material can be improved while the low density of the material is kept.

Description

Technical Field

[0001] This invention relates to a method for preparing a nickel-aluminum composite material. Background Technology

[0002] NiAl intermetallic compounds are characterized by their high melting point (1638°C) and low density (5.86 g / cm³). 3 With its excellent high-temperature oxidation resistance and good thermal conductivity, it is considered one of the most promising high-temperature structural materials, and has important application prospects in fields such as aero-engine blades, turbine disks, and thermal protection systems. However, current research has failed to balance the material's low density, room-temperature plasticity, and high-temperature strength, which severely limits its engineering applications.

[0003] To address these issues, scholars have explored various methods in recent years, such as alloying and second-phase dispersion strengthening. While these methods can improve strength to some extent, they often come at the cost of sacrificing plasticity and density, failing to fundamentally resolve the strength-toughness contradiction. In recent years, inspired by biological structures in nature, bimodal structure design has provided a new approach to overcoming the performance bottlenecks of NiAl-based composites. Studies have shown that bimodal structure materials, through multi-scale construction and interface optimization, can effectively suppress crack propagation, improve stress distribution, and enhance fracture toughness. Nevertheless, research on multi-scale bimodal structure-reinforced NiAl-based composites remains scarce. Summary of the Invention

[0004] The purpose of this invention is to address the problem that existing methods cannot simultaneously achieve the low density, room temperature plasticity, and high temperature strength of NiAl, thus severely hindering its application. Instead, this invention provides a method for strengthening NiAl-based composite materials through a multi-scale bimodal structure.

[0005] A method for strengthening NiAl-based composite materials through multi-scale bimodal structures is carried out according to the following steps:

[0006] 1. Weigh Ni, Al, V, Mo, Zr and B powders in a vacuum glove box, mix them evenly to obtain mixed metal powder; put the mixed metal powder into a ball mill jar, and then add grinding balls;

[0007] 2. Evacuate the ball mill jar, then introduce high-purity argon gas, repeat the operation, and then seal the ball mill jar. Place the sealed ball mill jar on a ball mill, first ball mill at 300 r / min~350 r / min for 2 h~3 h, then ball mill at 550 r / min~650 r / min for 1.5 h~3 h, finally evacuate the ball mill jar again, introduce a certain amount of oxygen into the jar, and ball mill at 450 r / min~500 r / min for 5 h~6 h, screen out the mixed metal powder with a particle size of 100 μm, continue ball milling the remaining mixed metal powder for 1 h~3 h, and screen out the mixed metal powder with a particle size of 30 μm.

[0008] 3. Mix the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm in a ball mill jar at a low speed to obtain a powder with uniformly mixed particle sizes.

[0009] The mass ratio of the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm mentioned in step three is (40~60):(60~40);

[0010] 4. Transfer the powder of two uniformly mixed particle sizes into a high-strength graphite mold, and place the high-strength graphite mold into a vacuum hot pressing sintering furnace. Apply pre-pressure through the pressure head, maintain pressure, release pressure and vacuum after the powder is compacted.

[0011] 5. After the vacuum degree reaches a certain value, heat the mold at a certain heating rate. After the temperature reaches 1400℃, keep it at that temperature for a period of time, and continue to apply pressure during the heat preservation process.

[0012] 6. After the heat preservation is completed, stop heating and let the furnace cool. When the temperature drops to 800℃, release the pressure. When the temperature drops below 400℃, turn off the diffusion pump and let it cool naturally to below 80℃. Take out the high-strength graphite mold to obtain a NiAl-based composite material with multi-scale bimodal structure reinforcement.

[0013] Advantages of this invention:

[0014] I. This invention discloses a method for strengthening NiAl-based composite materials through a multi-scale bimodal structure. Two uniformly mixed powder particles of different particle sizes are obtained through ball milling, and a bimodal structure with a continuous, staggered distribution is obtained using classical sintering theory at high temperature. Simultaneously, V(Mo) phase and ceramic particles are distributed within the material matrix and at the grain boundaries, respectively. This method can improve the strength and toughness of the material while maintaining its low density. It effectively addresses the problem in existing research that it is difficult to simultaneously achieve the low density, room temperature plasticity, and high-temperature strength of NiAl, thus severely hindering its application. This invention yields a well-formed NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material with excellent mechanical properties, showing a significant improvement over pure NiAl.

[0015] II. The pure NiAl intermetallic compound prepared by the present invention using the same preparation process has a room temperature ultimate compressive strength of 1208 MPa, a compression limit deformation of 25.5%, and a compressive yield strength of 95 MPa at 1000℃. In contrast, the NiAl-based composite material with multi-scale bimodal structure reinforcement prepared by the present invention has a room temperature ultimate compressive strength of 1832 MPa-2060 MPa, a compression limit deformation of 28.5%-39.5%, and a compressive yield strength of 158 MPa-190 MPa at 1000℃. Therefore, it can be seen that the mechanical properties of the NiAl-based composite material with multi-scale bimodal structure reinforcement (NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material) prepared by the present invention are significantly improved compared to pure NiAl.

[0016] This invention provides a NiAl-based composite material with multi-scale bimodal structure reinforcement. Attached Figure Description

[0017] Figure 1 The image shows the macroscopic microstructure of the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material prepared in Example 1.

[0018] Figure 2 Mesoscopic microstructure of the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material prepared in Example 1;

[0019] Figure 3 The image shows the microstructure of the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material prepared in Example 1.

[0020] Figure 4 The image shows the microstructure of the NiAl(B)-V-(Al2O3+ZrO2) composite material prepared in Example 2.

[0021] Figure 5 This is a microstructure diagram of the NiAl(B)-Mo-(Al2O3+ZrO2) composite material prepared in Example 3. Detailed Implementation

[0022] Specific Implementation Method 1: This implementation method is a method for strengthening NiAl-based composite materials through a multi-scale bimodal structure, which is carried out according to the following steps:

[0023] 1. Weigh Ni, Al, V, Mo, Zr and B powders in a vacuum glove box, mix them evenly to obtain mixed metal powder; put the mixed metal powder into a ball mill jar, and then add grinding balls;

[0024] 2. Evacuate the ball mill jar, then introduce high-purity argon gas, repeat the operation, and then seal the ball mill jar. Place the sealed ball mill jar on a ball mill, first ball mill at 300 r / min~350 r / min for 2 h~3 h, then ball mill at 550 r / min~650 r / min for 1.5 h~3 h, finally evacuate the ball mill jar again, introduce a certain amount of oxygen into the jar, and ball mill at 450 r / min~500 r / min for 5 h~6 h, screen out the mixed metal powder with a particle size of 100 μm, continue ball milling the remaining mixed metal powder for 1 h~3 h, and screen out the mixed metal powder with a particle size of 30 μm.

[0025] 3. Mix the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm in a ball mill jar at a low speed to obtain a powder with uniformly mixed particle sizes.

[0026] The mass ratio of the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm mentioned in step three is (40~60):(60~40);

[0027] 4. Transfer the powder of two uniformly mixed particle sizes into a high-strength graphite mold, and place the high-strength graphite mold into a vacuum hot pressing sintering furnace. Apply pre-pressure through the pressure head, maintain pressure, release pressure and vacuum after the powder is compacted.

[0028] 5. After the vacuum degree reaches a certain value, heat the mold at a certain heating rate. After the temperature reaches 1400℃, keep it at that temperature for a period of time, and continue to apply pressure during the heat preservation process.

[0029] 6. After the heat preservation is completed, stop heating and let the furnace cool. When the temperature drops to 800℃, release the pressure. When the temperature drops below 400℃, turn off the diffusion pump and let it cool naturally to below 80℃. Take out the high-strength graphite mold to obtain a NiAl-based composite material with multi-scale bimodal structure reinforcement.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the mass ratio of Ni, Al, V, Mo, Zr, and B powders mentioned in step one is (5.753~6.166):(2.699~2.888):(0~0.6):(0~0.4):0.296:0.1. The other steps are the same as in Specific Implementation Method One.

[0031] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the mass ratio of the grinding ball to the mixed metal powder in step one is (10~12):1. Other steps are the same as in Specific Implementation Method One or Two.

[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the Ni powder in step one has a particle size of 5μm to 20μm and a purity greater than 99.5%; the Al powder in step one has a particle size of 5μm to 50μm and a purity greater than 99.9%. The other steps are the same as in Specific Implementation Methods One to Three.

[0033] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the particle size of the V powder mentioned in step one is 5μm~50μm, and the purity is greater than 99.9%; the particle size of the Mo powder mentioned in step one is 10μm~50μm, and the purity is greater than 99.9%; the particle size of the Zr powder mentioned in step one is 5μm~50μm, and the purity is greater than 99.9%; the particle size of the B powder mentioned in step one is 10μm~50μm, and the purity is greater than 99.9%. The other steps are the same as in Specific Implementation Methods One to Four.

[0034] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the diameter of the grinding balls mentioned in step one is one or both of 8mm and 6mm; the grinding jar mentioned in step one is made of stainless steel and has a volume of 250mL~500mL. Other steps are the same as in Specific Implementation Methods One to Five.

[0035] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in the following ways: the number of repetitions in step two is 3 to 5 times; during the ball milling process in step two, each milling session lasts 10 to 20 minutes, followed by a 2 to 5 minute cooling period; and the ratio of the volume of oxygen introduced into the container in step two to the mass of the mixed metal powder is (100 mL to 110 mL): (9.5 g to 10 g). Other steps are the same as in Specific Implementation Methods One to Six.

[0036] Specific Implementation Method Eight: The difference between this implementation method and Specific Implementation Methods One to Seven is that the low-rate mixing described in step three is ball milling at 300 r / min to 350 r / min for 2 to 3 hours. The other steps are the same as in Specific Implementation Methods One to Seven.

[0037] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the flexural strength of the high-strength graphite mold described in step four is greater than 60 MPa; the pre-pressure applied in step four is 5 MPa to 10 MPa, and the holding time is 30 min to 60 min. Other steps are the same as in Specific Implementation Methods One to Eight.

[0038] Specific Implementation Method Ten: The difference between this implementation method and Specific Implementation Methods One through Nine is that in step five, the vacuum degree needs to reach 1×10⁻⁶. -4After applying pressure of MPa, the mold is heated at a rate of 15℃ / min to 30℃ / min until it reaches 1400℃. The temperature is then held for 30 to 60 minutes, during which a pressure of 40 MPa to 50 MPa is continuously applied. Other steps are the same as in embodiments one through nine.

[0039] The beneficial effects of the present invention are verified using the following embodiments:

[0040] Example 1: A method for strengthening NiAl-based composite materials through a multi-scale bimodal structure, specifically carried out according to the following steps:

[0041] 1. Weigh Ni, Al, V, Mo, Zr and B powders in a vacuum glove box, mix them evenly to obtain mixed metal powder; put the mixed metal powder into a ball mill jar, and then add grinding balls;

[0042] The mass ratio of Ni, Al, V, Mo, Zr and B powders mentioned in step one is 5.753:2.699:0.6:0.4:0.296:0.1;

[0043] The mass ratio of the grinding balls to the mixed metal powder in step one is 10:1;

[0044] The Ni powder mentioned in step one has a particle size of 8 μm and a purity greater than 99.5%.

[0045] The Al powder mentioned in step one has a particle size of 10 μm and a purity greater than 99.9%.

[0046] The V powder mentioned in step one has a particle size of 30 μm and a purity greater than 99.9%.

[0047] The Mo powder mentioned in step one has a particle size of 30 μm and a purity greater than 99.9%.

[0048] The Zr powder mentioned in step one has a particle size of 30 μm and a purity greater than 99.9%.

[0049] The particle size of powder B mentioned in step one is 10 μm, and the purity is greater than 99.9%.

[0050] The grinding balls mentioned in step one have diameters of 8mm and 6mm; the mass ratio of the 8mm diameter balls to the 6mm diameter balls is 6:4.

[0051] The ball mill jar mentioned in step one is made of stainless steel and has a volume of 250mL;

[0052] 2. Evacuate the ball mill jar, then introduce high-purity argon gas, repeat the operation 3 times, and then seal the ball mill jar. Place the sealed ball mill jar on the ball mill, and first ball mill at 350 r / min for 3 hours. After the original powder is mixed evenly, ball mill at 550 r / min for 2 hours. During this process, the powder and the grinding balls collide violently, and the powder continuously aggregates under high-energy impact to form large-sized mixed powder particles. Finally, evacuate the ball mill jar again, introduce a certain amount of oxygen into the jar, and ball mill at 450 r / min for 5 hours. Screen out the mixed metal powder with a particle size of 100 μm. Continue to ball mill the remaining mixed metal powder for 2 hours and screen out the mixed metal powder with a particle size of 30 μm.

[0053] In step two, after each 10-minute ball milling process, the ball is cooled for 2 minutes.

[0054] In step two, the volume ratio of a fixed amount of oxygen introduced into the container to the mass ratio of the mixed metal powder is 105.7 mL: 9.85 g.

[0055] 3. Mix the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm in a ball mill jar at a low speed to obtain a powder with uniformly mixed particle sizes.

[0056] The mass ratio of the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm mentioned in step three is 50:50.

[0057] The low-rate mixing described in step three involves ball milling at 300 r / min for 3 hours;

[0058] 4. Transfer the powder of two uniformly mixed particle sizes into a high-strength graphite mold, and place the high-strength graphite mold into a vacuum hot pressing sintering furnace. Apply pre-pressure through the pressure head, maintain pressure, release pressure and vacuum after the powder is compacted.

[0059] The flexural strength of the high-strength graphite mold mentioned in step four is greater than 60 MPa;

[0060] In step four, a pre-pressure of 10 MPa is applied, and the pressure is maintained for 60 minutes.

[0061] 5. After the vacuum degree reaches a certain value, heat the mold at a certain heating rate. After the temperature reaches 1400℃, keep it at that temperature for a period of time, and continue to apply pressure during the heat preservation process.

[0062] In step five, the vacuum level is expected to reach 1×10⁻⁶. -4 After applying MPa, the mold is heated at a heating rate of 30℃ / min. Once the temperature reaches 1400℃, it is held for 30 minutes, during which a pressure of 50MPa is continuously applied.

[0063] 6. After the heat preservation is completed, stop heating and let the furnace cool. When the temperature drops to 800℃, release the pressure. When the temperature drops below 400℃, turn off the diffusion pump and let it cool naturally to below 80℃. Take out the high-strength graphite mold to obtain a NiAl-based composite material with multi-scale bimodal structure reinforcement, namely NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material.

[0064] Figure 1 The image shows the macroscopic microstructure of the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material prepared in Example 1.

[0065] Depend on Figure 1 It can be seen that the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material generates a continuously distributed bimodal structure, with fine-grained regions mostly consisting of continuous, elongated strips interspersed with coarse-grained regions. According to classical sintering theory, the neck growth rate is inversely proportional to the powder particle radius. Therefore, in the early stages of sintering, a large number of small particles of the same size rapidly form a robust and well-developed neck. These rapidly combined small particle clusters are the prototypes of small-sized grains in the final structure. Subsequently, large powder particles also gradually combine around the small particle clusters. In the middle and later stages of sintering, grain growth begins to dominate in order to reduce the overall grain boundary energy. Grain boundaries move towards their curvature centers to reduce the area and curvature of the grain boundaries. Large grains further grow by engulfing surrounding small grains, thus forming some larger grain regions. As a result, the sample ultimately forms a bimodal structure with coexisting and interspersed coarse and fine grains.

[0066] Figure 2 Mesoscopic microstructure of the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material prepared in Example 1;

[0067] Figure 3 The image shows the microstructure of the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material prepared in Example 1.

[0068] Combination Figure 1-3 A multi-scale bimodal reinforced structure of the NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material can be obtained. From... Figure 1 As can be seen from (a) and (b), the NiAl alloy matrix exhibits an alternating bimodal microstructure, with elongated fine-grained regions bearing the main load and coarse-grained regions bearing a large amount of deformation. This macroscopic bimodal structure endows the matrix with excellent properties. V and Mo mainly form a pseudo-binary eutectic system with the matrix and react with each other during the reaction process to form... Figure 2 The V(Mo) phases shown in (a) and (b) demonstrate that the strip-like structures formed by these V(Mo) phases at the mesoscale can provide the material with intrinsic toughness; from Figure 3(a) It can be seen that a certain amount of nanoscale ceramic particles are distributed at the grain boundaries and within the grains of the bimodal matrix. These particles form a reinforcing structure at the microscale to pin and hinder dislocations, combined with Figure 3 (b) The SAED pattern indicates that the particles are mainly Al2O3 and ZrO2.

[0069] The NiAl-based composite material (NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material) with multi-scale bimodal structure reinforcement prepared in Example 1 has a room temperature compressive strength of 2030 MPa, a compressive deformation of 39.5%, and a compressive yield strength of 190 MPa at 1000 °C.

[0070] Example 2: The difference between this example and Example 1 is that the weighing of molybdenum powder is omitted in step one, and the mass ratio of nickel powder, aluminum powder, vanadium powder, zirconium powder, and boron powder in step one is 6.029:2.824:0.6:0.296:0.1. All other steps and parameters are the same as in Example 1.

[0071] The NiAl-based composite material (NiAl(B)-V-(Al2O3+ZrO2) composite material) with multi-scale bimodal structure reinforcement prepared in Example 2 has a room temperature compressive strength of 1832 MPa, a compressive deformation of 34.5%, and a compressive yield strength of 158 MPa at 1000 °C.

[0072] Example 3: The difference between this example and Example 1 is that the weighing of vanadium powder is omitted in step one, and the mass ratio of nickel powder, aluminum powder, molybdenum powder, zirconium powder, and boron powder in step one is 6.166:2.888:0.4:0.296:0.1. All other steps and parameters are the same as in Example 1.

[0073] The NiAl-based composite material (NiAl(B)-Mo-(Al2O3+ZrO2) composite material) with multi-scale bimodal structure reinforcement prepared in Example 3 has a room temperature compressive strength of 2060 MPa, a compressive deformation of 28.5%, and a compressive yield strength of 181 MPa at 1000 °C.

[0074] Figure 4 The image shows the microstructure of the NiAl(B)-V-(Al2O3+ZrO2) composite material prepared in Example 2.

[0075] Figure 5 The image shows the microstructure of the NiAl(B)-Mo-(Al2O3+ZrO2) composite material prepared in Example 3.

[0076] from Figure 4-5It can be seen that similar bimodal structures were also generated in the NiAl(B)-V-(Al2O3+ZrO2) samples in Example 2 and NiAl(B)-Mo-(Al2O3+ZrO2) in Example 3. The difference is that the V and Mo phases are both dispersed spherical, which mainly rely on the mechanical Orowan bypass mechanism to provide limited reinforcement. They are also prone to becoming the origin of microcracks due to interfacial stress concentration. Therefore, the strengthening effect is weaker than that of the long strip-shaped V(Mo) phase.

[0077] Comparative Example 1: The preparation method of NiAl intermetallic compound is carried out according to the following steps:

[0078] 1. Weigh Ni and Al powders in a vacuum glove box, mix them evenly to obtain mixed metal powder; put the mixed metal powder into a ball mill jar, and then add grinding balls;

[0079] The mass ratio of Ni to Al powder mentioned in step one is 6.851:3.149;

[0080] The mass ratio of the grinding balls to the mixed metal powder in step one is 10:1;

[0081] The Ni powder mentioned in step one has a particle size of 8 μm and a purity greater than 99.5%.

[0082] The Al powder mentioned in step one has a particle size of 10 μm and a purity greater than 99.9%.

[0083] The grinding balls mentioned in step one have a diameter of 8mm or 6mm; the mass ratio of the 8mm diameter balls to the 6mm diameter balls is 6:4.

[0084] The ball mill jar mentioned in step one is made of stainless steel and has a volume of 250mL;

[0085] 2. Evacuate the ball mill jar, then introduce high-purity argon gas, repeat the operation 3 times, and then seal the ball mill jar. Place the sealed ball mill jar on the ball mill and first ball mill at 350 r / min for 3 hours. After the original powder is mixed evenly, ball mill at 550 r / min for 2 hours. During this process, the powder and the grinding balls collide violently. Under the high-energy impact, the powder continuously aggregates to form large-sized mixed powder particles. Then ball mill at 450 r / min for 5 hours and screen out the mixed metal powder with a particle size of 100 μm. Continue to ball mill the remaining mixed metal powder for 2 hours and screen out the mixed metal powder with a particle size of 30 μm.

[0086] In step two, after each 10-minute ball milling process, the ball is cooled for 2 minutes.

[0087] 3. Mix the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm in a ball mill jar at a low speed to obtain a powder with uniformly mixed particle sizes.

[0088] The mass ratio of the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm mentioned in step three is 50:50.

[0089] The low-rate mixing described in step three involves ball milling at 300 r / min for 3 hours;

[0090] 4. Transfer the powder of two uniformly mixed particle sizes into a high-strength graphite mold, and place the high-strength graphite mold into a vacuum hot pressing sintering furnace. Apply pre-pressure through the pressure head, maintain pressure, release pressure and vacuum after the powder is compacted.

[0091] The flexural strength of the high-strength graphite mold mentioned in step four is greater than 60 MPa;

[0092] In step four, a pre-pressure of 10 MPa is applied, and the pressure is maintained for 60 minutes.

[0093] 5. After the vacuum degree reaches a certain value, heat the mold at a certain heating rate. After the temperature reaches 1400℃, keep it at that temperature for a period of time, and continue to apply pressure during the heat preservation process.

[0094] In step five, the vacuum level is expected to reach 1×10⁻⁶. -4 After applying MPa, the mold is heated at a heating rate of 30℃ / min. Once the temperature reaches 1400℃, it is held at that temperature for 60 minutes, during which a pressure of 50MPa is continuously applied.

[0095] 6. After the heat preservation is completed, stop heating and let the furnace cool. When the temperature drops to 800℃, release the pressure. When the temperature drops below 400℃, turn off the diffusion pump and let it cool naturally to below 80℃. Remove the high-strength graphite mold to obtain the NiAl intermetallic compound.

[0096] Comparative Example 1 shows that the pure NiAl intermetallic compound prepared using the same preparation process has a room temperature ultimate compressive strength of 1208 MPa, a compression limit deformation of 25.5%, and a compressive yield strength of 95 MPa at 1000 °C. In contrast, the NiAl-based composite material (NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material) with multi-scale bimodal structure reinforcement prepared in Example 1 has a room temperature ultimate compressive strength of 2030 MPa, a compression limit deformation of 39.5%, and a compressive yield strength of 190 MPa at 1000 °C. Therefore, it can be concluded that the mechanical properties of the NiAl-based composite material (NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material) with multi-scale bimodal structure reinforcement prepared in Example 1 are significantly improved compared to pure NiAl.

[0097] Comparative Example 2: The preparation method of NiAl(B)-Al2O3-ZrO2 composite material is carried out according to the following steps:

[0098] 1. Weigh Ni, Al, Zr and B powders in a vacuum glove box, mix them evenly to obtain mixed metal powder; put the mixed metal powder into a ball mill jar, and then add grinding balls;

[0099] The mass ratio of Ni, Al, Zr, and B powders mentioned in step one is 6.439:3.013:0.296:0.1;

[0100] The mass ratio of the grinding balls to the mixed metal powder in step one is 10:1;

[0101] The Ni powder mentioned in step one has a particle size of 8 μm and a purity greater than 99.5%.

[0102] The Al powder mentioned in step one has a particle size of 10 μm and a purity greater than 99.9%.

[0103] The Zr powder mentioned in step one has a particle size of 5μm~50μm and a purity greater than 99.9%;

[0104] The particle size of powder B mentioned in step one is 10μm~50μm, and the purity is greater than 99.9%.

[0105] The grinding balls mentioned in step one have a diameter of 8mm or 6mm; the mass ratio of the 8mm diameter balls to the 6mm diameter balls is 6:4.

[0106] The ball mill jar mentioned in step one is made of stainless steel and has a volume of 250mL;

[0107] 2. Evacuate the ball mill jar, then introduce high-purity argon gas, repeat the operation 3 times, and then seal the ball mill jar. Place the sealed ball mill jar on the ball mill, and first ball mill at 350 r / min for 3 hours. After the original powder is mixed evenly, ball mill at 550 r / min for 2 hours. During this process, the powder and the grinding balls collide violently, and the powder continuously aggregates under high-energy impact to form large-sized mixed powder particles. Finally, evacuate the ball mill jar again, introduce a certain amount of oxygen into the jar, and ball mill at 450 r / min for 5 hours. Screen out the mixed metal powder with a particle size of 100 μm. Continue to ball mill the remaining mixed metal powder for 2 hours and screen out the mixed metal powder with a particle size of 30 μm.

[0108] In step two, after each 10-minute ball milling process, the ball is cooled for 2 minutes.

[0109] In step two, the volume ratio of a fixed amount of oxygen introduced into the container to the mass ratio of the mixed metal powder is 105.7 mL: 9.85 g.

[0110] 3. Mix the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm in a ball mill jar at a low speed to obtain a powder with uniformly mixed particle sizes.

[0111] The mass ratio of the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm mentioned in step three is 50:50.

[0112] The low-rate mixing described in step three involves ball milling at 300 r / min for 3 hours;

[0113] 4. Transfer the powder of two uniformly mixed particle sizes into a high-strength graphite mold, and place the high-strength graphite mold into a vacuum hot pressing sintering furnace. Apply pre-pressure through the pressure head, maintain pressure, release pressure and vacuum after the powder is compacted.

[0114] The flexural strength of the high-strength graphite mold mentioned in step four is greater than 60 MPa;

[0115] In step four, a pre-pressure of 10 MPa is applied, and the pressure is maintained for 60 minutes.

[0116] 5. After the vacuum degree reaches a certain value, heat the mold at a certain heating rate. After the temperature reaches 1400℃, keep it at that temperature for a period of time, and continue to apply pressure during the heat preservation process.

[0117] In step five, the vacuum level is expected to reach 1×10⁻⁶. -4 After applying MPa, the mold is heated at a heating rate of 10℃ / min. Once the temperature reaches 1400℃, it is held at that temperature for 60 minutes, during which a pressure of 50MPa is continuously applied.

[0118] 6. After the heat preservation is completed, stop heating and let the furnace cool. When the temperature drops to 800℃, release the pressure. When the temperature drops below 400℃, turn off the diffusion pump and let it cool naturally to below 80℃. Take out the high-strength graphite mold to obtain the NiAl(B)-Al2O3-ZrO2 composite material.

[0119] Comparative Example 2, prepared using the same process, showed a room-temperature compressive strength of 1649 MPa, a compression limit of 39%, and a compressive yield strength of 130 MPa at 1000 °C. In contrast, the NiAl-based composite material (NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material) with multi-scale bimodal reinforcement prepared in Example 1 showed a room-temperature compressive strength of 2030 MPa, a compression limit of 39.5%, and a compressive yield strength of 190 MPa at 1000 °C. Therefore, it can be concluded that the mechanical properties of the NiAl-based composite material (NiAl(B)-V(Mo)-(Al2O3+ZrO2) composite material) with multi-scale bimodal reinforcement prepared in Example 1 are significantly improved compared to NiAl(B)-Al2O3-ZrO2.

Claims

1. A method for strengthening NiAl-based composite materials through a multi-scale bimodal structure, characterized in that... The method is performed according to the following steps:

1. Weigh Ni, Al, V, Mo, Zr and B powders in a vacuum glove box, mix them evenly to obtain mixed metal powder; put the mixed metal powder into a ball mill jar, and then add grinding balls; 2. Evacuate the ball mill jar, then introduce high-purity argon gas, repeat the operation, and then seal the ball mill jar. Place the sealed ball mill jar on a ball mill, first ball mill at 300 r / min~350 r / min for 2 h~3 h, then ball mill at 550 r / min~650 r / min for 1.5 h~3 h, finally evacuate the ball mill jar again, introduce a certain amount of oxygen into the jar, and ball mill at 450 r / min~500 r / min for 5 h~6 h, screen out the mixed metal powder with a particle size of 100 μm, continue ball milling the remaining mixed metal powder for 1 h~3 h, and screen out the mixed metal powder with a particle size of 30 μm.

3. Mix the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm in a ball mill jar at a low speed to obtain a powder with uniformly mixed particle sizes. The mass ratio of the mixed metal powder with a particle size of 100 μm and the mixed metal powder with a particle size of 30 μm mentioned in step three is (40~60):(60~40); 4. Transfer the powder of two uniformly mixed particle sizes into a high-strength graphite mold, and place the high-strength graphite mold into a vacuum hot pressing sintering furnace. Apply pre-pressure through the pressure head, maintain pressure, release pressure and vacuum after the powder is compacted.

5. After the vacuum degree reaches a certain value, heat the mold at a certain heating rate. After the temperature reaches 1400℃, keep it at that temperature for a period of time, and continue to apply pressure during the heat preservation process.

6. After the heat preservation is completed, stop heating and let the furnace cool. When the temperature drops to 800℃, release the pressure. When the temperature drops below 400℃, turn off the diffusion pump and let it cool naturally to below 80℃. Take out the high-strength graphite mold to obtain a NiAl-based composite material with multi-scale bimodal structure reinforcement.

2. The method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... The mass ratio of Ni, Al, V, Mo, Zr and B powders mentioned in step one is (5.753~6.166):(2.699~2.888):(0~0.6):(0~0.4):0.296:0.

1.

3. The method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... The mass ratio of the grinding ball to the mixed metal powder in step one is (10~12):

1.

4. The method for preparing NiAl-based composite materials reinforced by multi-scale bimodal structure according to claim 1, characterized in that... The Ni powder mentioned in step one has a particle size of 5μm to 20μm and a purity greater than 99.5%; the Al powder mentioned in step one has a particle size of 5μm to 50μm and a purity greater than 99.9%.

5. The method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... The V powder mentioned in step one has a particle size of 5μm~50μm and a purity greater than 99.9%; the Mo powder mentioned in step one has a particle size of 10μm~50μm and a purity greater than 99.9%; the Zr powder mentioned in step one has a particle size of 5μm~50μm and a purity greater than 99.9%; the B powder mentioned in step one has a particle size of 10μm~50μm and a purity greater than 99.9%.

6. The method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... The diameter of the grinding balls mentioned in step one is one or both of 8mm and 6mm; the grinding jar mentioned in step one is made of stainless steel and has a volume of 250mL~500mL.

7. The method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... The repeated operation in step two is 3 to 5 times; during the ball milling process in step two, each ball milling process lasts 10 to 20 minutes, followed by cooling for 2 to 5 minutes; the volume ratio of a fixed amount of oxygen introduced into the container in step two to the mass ratio of the mixed metal powder is (100 mL to 110 mL): (9.5 g to 10 g).

8. The method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... The low-rate mixing described in step three involves ball milling at 300 r / min to 350 r / min for 2 to 3 hours.

9. A method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... The high-strength graphite mold mentioned in step four has a flexural strength greater than 60 MPa; the pre-pressure applied in step four is 5 MPa to 10 MPa, and the holding time is 30 min to 60 min.

10. A method for strengthening NiAl-based composite materials through a multi-scale bimodal structure according to claim 1, characterized in that... In step five, the vacuum level is expected to reach 1×10⁻⁶. -4 After applying MPa, the mold is heated at a rate of 15℃ / min to 30℃ / min until it reaches 1400℃. Then, it is held at this temperature for 30 to 60 minutes, during which a pressure of 40 MPa to 50 MPa is continuously applied.

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