Textured toughened high-entropy max composite phase ceramic material and preparation method thereof
By preparing M2AlC and M4AlC3 dual-phase high-entropy MAX composite ceramic materials and using a secondary hot-pressing sintering process to achieve texturing toughening, the problem of insufficient fracture toughness of high-entropy MAX phase ceramic materials was solved, and the fracture toughness of the materials was improved, making them suitable for aerospace and precision manufacturing fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LANZHOU INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2026-03-16
- Publication Date
- 2026-05-29
AI Technical Summary
Existing high-entropy MAX phase ceramic materials have insufficient fracture toughness, and existing toughening methods are complex or costly. Research on texturing preparation methods for medium/high-entropy MAX phases is limited and cumbersome.
By designing the composition and controlling the process, a high-entropy MAX composite phase ceramic material composed of M2AlC and M4AlC3 dual phases was prepared. The microstructure was oriented by a two-stage hot pressing sintering method. Combined with the high-entropy effect and texturing, the fracture toughness was improved.
It significantly improves the fracture toughness of high-entropy MAX phase ceramic materials to 13.04 MPa·m1/2, with a toughening effect of 13.36%~103.43%, making it suitable for high-toughness structural materials in aerospace and precision manufacturing fields.
Smart Images
Figure CN122102694A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of medium / high entropy MAX phase ceramics, specifically to a textured toughened high entropy MAX composite phase ceramic material and its preparation method. Background Technology
[0002] As modern industry upgrades towards extreme service environments and high-efficiency functional integration, the comprehensive performance requirements of materials for equipment components in fields such as aerospace are constantly increasing. Among these requirements, fracture toughness, a key factor in determining the service life of components, is one of the key factors in determining the service life of components.
[0003] MAX phase ceramics combine the excellent properties of both metals and ceramics, such as the thermal and electrical conductivity and machinability of metals, and the corrosion resistance and radiation resistance of ceramics. These materials hold great promise for applications in harsh service environments. In particular, MAX phase materials exhibit a typical lamellar microstructure, which deflects and bridges crack propagation during material deformation and failure. Furthermore, the lamellar structure itself undergoes twisting and other behaviors; these energy dissipation mechanisms endow the materials with high fracture toughness. Although MAX phase materials show a significant improvement in fracture toughness compared to traditional ceramics, the current MAX phase materials with single-element composition at the M-site and isotropic microstructure have not yet reached their full potential, leaving considerable room for performance improvement.
[0004] Multi-component high-entropy design in composition, combined with texturing control of microstructure, provides an effective way to further improve the fracture toughness of MAX phases. The four "high-entropy effects," as well as the texturing microstructure and the optimal arrangement of crystal orientations, can enable materials to exhibit extreme performance in specific directions.
[0005] Currently, although research has explored microstructure texturing construction schemes for MAX phases, most studies focus on non-medium / high entropy materials with single M-site elements (Journal of Materials Science & Technology, 2020, 38: 86-92; Journal of the European Ceramic Society, 2020, 40: 5258-5271.), and are accompanied by high costs and scarce equipment resources, such as the control of external electromagnetic fields (Journal of American Ceramic Society, 2011, 94 (2): 410-415.). In addition, there are few studies on texturing preparation methods for medium / high entropy MAX phases, and the construction and preparation steps are extremely cumbersome (Journal of the European Ceramic Society, 2024, 44: 6889-6900.), and the fracture toughness still needs to be improved.
[0006] Therefore, the combined regulation of multiple elements at the M site needs further exploration, and there is an urgent need to find a simple, economical and easy-to-operate method for texturing preparation. Summary of the Invention
[0007] The purpose of this invention is to overcome the problems of insufficient fracture toughness, complex toughening methods, or high costs of high-entropy MAX phase ceramic materials in the prior art, and to provide a textured toughened high-entropy MAX composite phase ceramic material and its preparation method.
[0008] This invention aims to achieve texturized toughening of high-entropy MAX phase ceramics by combining composition design with process control, thereby significantly improving their fracture toughness in specific directions to meet the stringent requirements of aerospace, precision manufacturing and other fields for high-toughness structural materials.
[0009] To achieve the above objectives, the present invention adopts the following technical solution: First, the present invention provides a textured toughened high-entropy MAX composite phase ceramic material, wherein the ceramic material is in the form of a bulk and is composed of two phases, M2AlC and M4AlC3, wherein M is a high-entropy combination of four elements, Ti, V, Nb and Ta; the microstructure of the ceramic material is a directionally arranged lamellar morphology, and the crystal orientation texture factor is not less than 0.7.
[0010] Preferably, the fracture toughness of the ceramic material is ≥13.0 MPa·m. 1 / 2 A further preferred value is 13.04 MPa·m 1 / 2 .
[0011] Secondly, this invention provides a method for preparing the above-mentioned textured toughened high-entropy MAX composite phase ceramic material, comprising the following steps: 1) Ingredients and mixing: Ti powder, V powder, Nb powder, Ta powder, Al powder and C powder are mixed according to stoichiometric ratio, wet ball milled under inert atmosphere, and dried to obtain mixed powder; 2) Initial sintering: The mixed powder obtained in step 1) is subjected to initial hot pressing sintering to obtain the M2AlC high-entropy MAX phase ceramic precursor; 3) Secondary hot pressing sintering: The M2AlC high-entropy MAX phase ceramic precursor obtained in step 2) is subjected to secondary hot pressing sintering. The grains are oriented and partially transformed by high-temperature deformation, and finally, M2AlC and M4AlC3 biphase high-entropy MAX phase ceramics with textured microstructure are obtained.
[0012] Preferably, in step 1), the molar ratio of the raw materials is: total amount of M-site metal element powder: Al powder: C powder = 2 : (1.1~1.2) : 0.9; wherein the M-site metal element powder is composed of Ti powder, V powder, Nb powder, Ta powder, etc.
[0013] Preferably, the purity of Ti powder, V powder, Nb powder, Ta powder, Al powder and C powder mentioned in step 1) is ≥99%, and the powder particle size is not less than 325 mesh.
[0014] As a preferred embodiment, the wet ball milling process described in step 1) is as follows: the raw material is placed in a ball milling jar lined with zirconia, anhydrous ethanol is added as the ball milling medium, the ball-to-material mass ratio is (2~3):1, and the material is ball milled at a speed of 300~450 rpm for 10~15 hours under an argon atmosphere; after the ball milling is completed, the material is vacuum dried at 50℃~70℃ for 10~18 hours.
[0015] Preferably, the initial hot-pressing sintering process parameters in step 2) are: under a vacuum degree ≤ 10 -3 Under Pa conditions, apply a pressure of 30~40 MPa and heat to 1500℃~1600℃ at a heating rate of 5-15℃ / min, and hold for 1.5~3 hours.
[0016] Preferably, the secondary hot-pressing sintering process parameters in step 3) are: (vacuum degree ≤ 10) -3 Under Pa conditions, apply a pressure of 20~40 MPa, gradually increase the temperature to 1600℃~1670℃, and hold for 5~9 hours.
[0017] As a further preferred option, the staged heating procedure is as follows: first, the temperature is increased to 1600℃ at a rate of 8-12℃ / min, and then increased to the target sintering temperature of 1600℃~1670℃ at a rate of 3-8℃ / min.
[0018] Finally, this invention provides the application of the above-mentioned textured toughened high-entropy MAX composite phase ceramic material in the preparation of structural components requiring high toughness, including but not limited to high-temperature thermal insulation parts, protective shells, precision machine tool guides, and aerospace structural components.
[0019] Compared with the prior art, the present invention has the following advantages: 1. This invention aims to improve the mechanical properties of high-entropy MAX phases. It uses a secondary hot-pressing sintering method and controls the preparation process to texture M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite phase ceramics to improve their fracture toughness. Through the synergistic effect of grain orientation and high-entropy solid solution strengthening, the mechanical properties in specific directions are improved, thereby achieving the textured toughening design of M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite phase ceramic materials.
[0020] 2. This invention realizes the preparation of high-entropy MAX phase with textured toughening by combining M2AlC and M4AlC3, providing a new approach for preparing M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite phase materials with high texture and optimized performance.
[0021] 3. The present invention achieves a fracture toughness of 13.04 MPa·m for the target textured high-entropy MAX phase through texturing toughening. 1 / 2 Compared with untextured high-entropy MAX phase and existing ceramic materials, the fracture toughness was improved by 13.36%~103.43%, achieving toughening of high-entropy MAX phase ceramic materials.
[0022] 4. The preparation process of this invention is simple. By adjusting the process parameters of hot pressing and sintering, the prepared high-entropy MAX phase ceramic has excellent mechanical properties (fracture toughness), and is particularly suitable for special workpieces that require high toughness under service conditions.
[0023] This method not only significantly improves the toughness of high-entropy MAX phase ceramics, but also broadens their application prospects in the field of high-performance structural materials. Attached Figure Description
[0024] Figure 1 XRD pattern (a) and SEM microstructure (b) of the M2AlC MAX phase precursor after initial hot pressing and sintering.
[0025] Figure 2 The XRD patterns of textured high-entropy MAX multiphase ceramics prepared in Examples 1-3 of this invention, wherein a-Example 1, b-Example 2, and c-Example 3.
[0026] Figure 3 The texturized high-entropy MAX multiphase ceramic SEM microstructures prepared in Examples 1-3 of this invention, wherein a-Example 1, b-Example 2, and c-Example 3. Detailed Implementation
[0027] The present invention will be further described in detail below with reference to specific embodiments, but this should not be construed as limiting the present invention in any way. Unless otherwise specified, the technical means used in the embodiments are all conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.
[0028] Example 1 A textured and toughened high-entropy MAX composite phase ceramic material is prepared by the following steps: 1) Prepare the ingredients by mixing Ti : V : Nb : Ta : Al : C = 0.5 : 0.5 : 0.5 : 0.5 : 1.2 : 0.9, with a total weight of 20g; The purity of the Ti powder, V powder, Nb powder, Ta powder, Al powder, and C powder is ≥99%, and the particle size is not less than 325 mesh. 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a zirconia ball-to-raw material mass ratio of 3:1. Add 25% anhydrous ethanol by weight of the raw material as the milling medium. Then, evacuate the vacuum ball mill jar and introduce argon gas. Repeat this operation 3 times. Place the ball mill jar in a planetary ball mill and mill at a speed of 300 rpm for 10 hours. 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a vacuum degree of -0.06MPa ~ -0.08MPa and a temperature of 60℃ for 12 hours. After drying, turn off the vacuum drying oven and take out the sample to cool to room temperature. 4) The dried mixed powder obtained in step 3) is cold-pressed under a pressure of 20 MPa to obtain a green blank, which is then placed in a graphite mold and hot-pressed and sintered in a vacuum environment. The sintering process is as follows: the vacuum hot-pressing sintering furnace is evacuated to 10 MPa at room temperature. -3 Below Pa, the temperature was increased to 1500℃ at 10℃ / min, held for 90min, and the loading pressure was 30MPa. After the holding period, the temperature was reduced and unloaded, and the furnace was cooled to obtain M2AlC (M=Ti,V,Nb,Ta)MAX phase ceramic. 5) Place the block sample obtained in step 4) under a diamond wire cutter to cut it into small-sized samples to ensure that the block sample has the conditions for texturing when it is sintered again. 6) Place the cut block sample from step 5) back into the graphite mold and perform hot pressing sintering in a vacuum environment. The sintering process is as follows: evacuate the vacuum hot pressing sintering furnace to 10°C at room temperature. -3 Below Pa, the temperature was increased to 1600℃ at 10℃ / min, then increased to 1660℃ at 5℃ / min, with a loading pressure of 24MPa, and held for 5.5h. After the holding period, the temperature was lowered and unloaded, and the furnace was cooled to obtain the target sample: textured M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite phase ceramic. According to XRD, its texture factor LotgeringFactor was calculated to be 0.72.
[0029] Example 2 A textured and toughened high-entropy MAX composite phase ceramic material is prepared using a method that is basically the same as that in Example 1, except that: In step 4), the sintering process is as follows: the vacuum hot pressing sintering furnace is evacuated to 10 at room temperature. -3Below Pa, the temperature was increased to 1500℃ at 10℃ / min, held for 120min, and the loading pressure was 30MPa. After the holding period, the temperature was reduced and unloaded, and the furnace was cooled to obtain M2AlC (M=Ti,V,Nb,Ta)MAX phase ceramic. In step 6), the sintering process is as follows: the vacuum hot pressing sintering furnace is evacuated to 10 at room temperature. -3 Below Pa, the temperature was increased to 1600℃ at 10℃ / min, then increased to 1660℃ at 5℃ / min, with a loading pressure of 35MPa, and held for 5.5h. After the holding period, the temperature was lowered and unloaded, and the furnace was cooled to obtain the target sample: textured M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite phase ceramic. According to XRD, its texture factor, Lotgering Factor, was 0.72.
[0030] Example 3 A textured and toughened high-entropy MAX composite phase ceramic material is prepared using a method that is basically the same as that in Example 1, except that: In step 1), the total weight of the ingredients is 50g; In step 4), the sintering process is as follows: the vacuum hot pressing sintering furnace is evacuated to 10 at room temperature. -3 Below Pa, the temperature is increased to 1500℃ at 10℃ / min, held for 180min, and loaded with a pressure of 30MPa. After the holding period, the temperature is reduced and unloaded, and the furnace is cooled to obtain M2AlC (M=Ti,V,Nb,Ta)MAX phase ceramic.
[0031] In step 6), the sintering process is as follows: the vacuum hot pressing sintering furnace is evacuated to 10 at room temperature. -3 Below Pa, the temperature was increased to 1600℃ at 10℃ / min, then increased to 1650℃ at 5℃ / min, with a loading pressure of 40MPa, and held for 7.5h. After the holding period, the temperature was lowered and unloaded, and the sample was cooled with the furnace to obtain the target sample: textured M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite phase ceramic. According to XRD, its texture factor, Lotgering Factor, was 0.74.
[0032] The regulatory mechanism of this invention is as follows: texturing toughening improves the toughness of high-entropy MAX phase ceramic materials by selectively arranging grains and crystal orientations, and by synergistically utilizing mechanisms such as crack deflection, bifurcation, bridging and microcrack passivation.
[0033] The structural characterization and performance evaluation of the products in the examples were performed, and the results are as follows: Structural characterization Characterization of textured high-entropy MAX phase ceramics prepared in Examples 1-3 Figure 1The images show the XRD patterns and SEM images of the M2AlC (M=Ti, V, Nb, Ta) MAX phase precursors prepared by the initial hot pressing in Examples 1-3. The XRD patterns indicate that the phase composition is relatively pure. The SEM microstructure shows that the MAX phase precursor lamellar structure is isotropic and does not exhibit directional preferential arrangement.
[0034] Figure 2 The XRD patterns of the textured, toughened, high-entropy MAX composite phases obtained by secondary sintering in Examples 1-3 are analyzed on the hot-pressed surface. It can be seen that the target material includes two phases, M2AlC and M4AlC3 (M = Ti, V, Nb, Ta), and the diffraction peaks after 50° basically disappear. The remaining peaks are mainly on the (0 0 2l) (l = integers 1-6) crystal planes between 5 and 50°, indicating that the target material exhibits a preferred arrangement of crystal orientations, i.e., the crystal plane {0 0 2l} / / the hot-pressed surface or the c-axis of the unit cell ⊥ the hot-pressed surface. The texture factors obtained from the calculations for the three examples are 0.72, 0.72, and 0.74, respectively.
[0035] Figure 3 The images show SEM images of the textured, toughened, high-entropy MAX composite phases obtained after secondary sintering in Examples 1-3. It can be seen that the lamellar structure is oriented, meaning the grain structure has undergone texturing.
[0036] Performance Evaluation Performance Evaluation of Textured High-Entropy MAX Phase Ceramics Prepared in Example 3 The fracture toughness of the target textured high-entropy M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite phase ceramic with a crystal orientation texture factor of 0.74 in Example 3 was tested using the single-sided notched beam method, and compared with the self-prepared single-phase untextured M2AlC and M4AlC3 (M=Ti, V, Nb, Ta) materials.
[0037] The specimen dimensions are length × width × height = 20 mm × 2 mm × 4 mm, span is 16 mm, notch width is 0.2 mm, notch depth is 2 mm, loading rate is 0.05 mm / min, and the notch cut surfaces of the target material are the hot-pressed stress surface (denoted as ∥c axis) and the side surface (denoted as ⊥c axis) of the specimen, respectively, to characterize the anisotropy of the fracture toughness of the target material.
[0038] As shown in Table 1, the fracture toughness of the prepared target textured high-entropy MAX phase exhibits anisotropy, with higher fracture toughness in the ∥c axis direction than in the ⊥c axis direction. Compared with the self-prepared isotropic M2AlC and M4AlC3 (M=Ti, V, Nb, Ta) materials, the fracture toughness in the ⊥c axis direction is increased by 61.47% and 13.36%, respectively, and the fracture toughness in the ∥c axis direction is increased by 103.43% and 42.83%, respectively. Compared with the textured high-entropy M4AlC3 phase ceramics (M=Ti, V, Mo, Nb, Ta) in the literature (Journal of American Ceramic Society, 2011, 94 (2): 410-415), the fracture toughness in the ∥c axis direction and the ⊥c axis direction is increased by 48.18% and 26.22%, respectively.
[0039] This indicates that under this preparation method, the high-entropy effect of the selected element at the M site combined with the texturing control of the microstructure can significantly enhance the toughening effect of the MAX phase.
[0040] Table 1. Comparison of fracture toughness between the textured toughened M2AlC / M4AlC3 (M=Ti, V, Nb, Ta) composite ceramic prepared in Example 3 and other high-entropy MAX phase ceramics. Note: [1] represents data from the cited literature (Journal of American Ceramic Society, 2011, 94(2): 410-415).
[0041] In summary, this invention successfully prepared a highly textured M2AlC / M4AlC3 dual-phase high-entropy MAX ceramic using a simple two-stage hot-pressing sintering process. This material achieves a significant improvement in fracture toughness by utilizing the synergistic effect of the high-entropy effect and the textured structure, exhibiting performance far superior to untextured single-phase materials and textured materials reported in the literature. This preparation method is simple, low-cost, and easily industrialized, showing broad application prospects in aerospace, precision manufacturing, and other fields requiring high toughness.
[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A textured, toughened, high-entropy MAX composite phase ceramic material, characterized in that, The ceramic material is in bulk form and is composed of two phases, M2AlC and M4AlC3, wherein M is a high-entropy combination of four elements: Ti, V, Nb, and Ta. The microstructure of the ceramic material exhibits a directional lamellar morphology, and the crystal orientation texture factor is not less than 0.
7.
2. The textured toughened high-entropy MAX composite phase ceramic material according to claim 1, characterized in that, The fracture toughness of the ceramic material is ≥13.0 MPa·m 1 / 2 .
3. A method for preparing the textured toughened high-entropy MAX composite phase ceramic material as described in claim 1 or 2, characterized in that, Includes the following steps: 1) Ingredients and mixing: Ti powder, V powder, Nb powder, Ta powder, Al powder and C powder are mixed according to stoichiometric ratio, wet ball milled under inert atmosphere, and dried to obtain mixed powder; 2) Initial sintering: The mixed powder obtained in step 1) is subjected to initial hot pressing sintering to obtain M2AlC high-entropy MAX phase ceramic precursor; 3) Secondary hot pressing sintering: The M2AlC high-entropy MAX phase ceramic precursor obtained in step 2) is subjected to secondary hot pressing sintering. The grains are oriented and partially transformed by high-temperature deformation, and finally, M2AlC and M4AlC3 biphase high-entropy MAX phase ceramics with textured microstructure are obtained.
4. The preparation method according to claim 3, characterized in that, In step 1), the molar ratio of the raw materials is: total amount of M-site metal element powder: Al powder: C powder = 2 : (1.1~1.2) : 0.9; wherein, the M-site metal element powder is composed of Ti powder, V powder, Nb powder, Ta powder and other molar amounts.
5. The preparation method according to claim 3, characterized in that, Step 2) The initial hot-pressing sintering process parameters are: under a vacuum degree ≤10 -3 Under Pa conditions, apply a pressure of 30~40 MPa and heat to 1500℃~1600℃ at a heating rate of 5-15℃ / min, and hold for 1.5~3 hours.
6. The preparation method according to claim 3, characterized in that, Step 3) The secondary hot pressing sintering process parameters are: under a vacuum degree ≤10 -3 Under Pa conditions, apply a pressure of 20~40 MPa, gradually increase the temperature to 1600℃~1670℃, and hold for 5~9 hours.
7. The preparation method according to claim 6, characterized in that, The phased heating procedure is as follows: first, the temperature is increased to 1600℃ at a rate of 8-12℃ / min, and then increased to the target sintering temperature of 1600℃~1670℃ at a rate of 3-8℃ / min.
8. The preparation method according to claim 3, characterized in that, The purity of Ti powder, V powder, Nb powder, Ta powder, Al powder and C powder mentioned in step 1) is ≥99%, and the powder particle size is not less than 325 mesh.
9. The preparation method according to claim 3, characterized in that, The wet ball milling process described in step 1) is as follows: place the raw material in a ball milling jar, add 20%~30% anhydrous ethanol of the total weight of the raw material as the ball milling medium, and the ball-to-material mass ratio is (2~3):
1. Ball mill at a speed of 300~450 rpm for 10~15 hours under an argon atmosphere. After ball milling, vacuum dry at 50℃~70℃ for 10~18 hours.
10. The application of the textured toughened high-entropy MAX composite phase ceramic material according to claim 1 or 2, or the textured toughened high-entropy MAX composite phase ceramic material prepared by the method according to any one of claims 3-9, in the preparation of structural components requiring high toughness.