High-temperature high-strength high-entropy max phase bulk material and preparation and application thereof

Abstract

The application discloses a high-temperature high-strength high-entropy MAX phase bulk material and a preparation method thereof. The high-temperature high-strength high-entropy MAX phase bulk material is expressed as M2AX, M is a combination of any four or more of Ti, Zr, V, Nb and Ta, the atomic percentage of each component in the M sublattice is between 5% and 35%, the sum of the atomic percentages of Zr and V is less than or equal to 16.7%, A is an Al element, and X is a C element. The bulk MAX phase material is prepared by a spark plasma sintering method. The high-temperature high-strength high-entropy MAX material prepared by the application has high purity and excellent mechanical properties at room temperature and high temperature, can be used for preparing high-temperature structural parts under special working conditions, and has a wide application prospect in the high-temperature field.

Description

Technical Field

[0001] This invention relates to the field of MAX phase ceramics, specifically to a high-temperature, high-strength, high-entropy MAX phase bulk material with excellent comprehensive mechanical properties at room temperature and high temperature, and its preparation method. Background Technology

[0002] MAX phases are a class of ternary compounds with a microscopic layered structure and the molecular formula M. n+1 AX n In this MAX phase, M represents pre-transition metals from groups IIIB, IVB, VB, and VIB; A primarily represents elements from groups IIIA and IVB; and X represents carbon or nitrogen. The MAX phase has a hexagonal crystal structure with space group P6 / 3mmc, and its unit cell consists of M... n+1 X n The MAX phase is formed by alternating stacking of unit cells and A-plane atoms, with n = 1, 2, 3, commonly referred to as the 211, 312, 413 phases. The atomic bonding in MAX phase ceramic compounds involves covalent, ionic, and metallic bonds, thus combining many advantages of both metals and ceramics, including low density, high modulus, good electrical / thermal conductivity, thermal shock resistance, damage tolerance, and excellent resistance to high-temperature oxidation. These superior properties give it broad application prospects and have therefore attracted widespread attention from researchers.

[0003] However, traditional MAX phases lack strengthening mechanisms and effective slip systems, resulting in low room temperature and high temperature strength, with a fracture strain of less than 1.5% at room temperature and strain softening under high temperature loading. This greatly limits the further practical application of MAX phase materials.

[0004] "High entropy" is a new materials design theory that has emerged in recent years and has become a major focus in materials research. Its concept originated from high-entropy alloys. Due to the high mixing entropy, lattice distortion, short chemical order, and slow diffusion resulting from the "high entropy effect," high-entropy alloys, especially refractory high-entropy alloys, still possess excellent mechanical properties at ultra-high temperatures. In recent years, some reports have attempted to synthesize aluminum-containing high-entropy MAX phase materials and found that increasing the number of components increases the system configuration entropy, thereby improving the room temperature hardness and flexural strength of the MAX phase materials. However, the low purity of the synthesized high-entropy MAX phases and the presence of impurity phases affect the improvement of their overall mechanical properties. Therefore, there is an urgent need to develop high-purity, high-strength, high-entropy MAX phase bulk materials and their preparation methods. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a high-purity, high-entropy MAX phase material with excellent comprehensive mechanical properties at both room temperature and high temperature, along with its preparation method, by controlling the content of solid solution elements.

[0006] The technical solution of the present invention is: a high-temperature, high-strength, high-entropy MAX phase bulk material, the molecular formula of which is M2AX, where M is any combination of four or more of the five elements Ti, Zr, V, Nb, and Ta, the atomic percentage of each component in the M sublattice is between 5% and 35%, and the sum of the atomic percentages of Zr and / or V is less than or equal to 16.7%, A is Al, and X is C.

[0007] Furthermore, the high-temperature, high-strength, high-entropy MAX phase bulk material has high purity, with the volume fraction of the 211-type MAX phase not less than 95%.

[0008] Furthermore, the high-temperature, high-strength, high-entropy MAX phase bulk material exhibits excellent mechanical properties at both room temperature and high temperature. At room temperature, the maximum compressive strength exceeds 1500 MPa, the fracture strain exceeds 1.5%, and the yield strength at 1200℃ exceeds 300 MPa, with no obvious strain softening phenomenon.

[0009] Furthermore, when M is Ti a Zr b V c Nb d Ta e When a = d = e and b = c = 8.3%, the chemical formula of this high-temperature, high-strength, high-entropy MAX phase is (TiZr). 0.3 V 0.3 NbTa)2AlC has a maximum compressive strength of 1800 MPa at room temperature, a fracture strain of 2.03%, and a yield strength of 360 MPa at 1200℃.

[0010] Furthermore, when M is Ti a Zr b Nb d Ta e When a = d = e and b = 16.7%, the chemical formula of the MAX phase is (TiZr). 0.6 NbTa)2AlC has a maximum compressive strength of 1687 MPa at room temperature, a fracture strain of 1.84%, and a yield strength of 558 MPa at 1200℃.

[0011] Furthermore, when M is Ti a Zr b Nb d Ta e When a = 29.7%, b = 16.7%, and d = e = 26.8%, the chemical formula of the MAX phase is (Ti 29.7 Zr 16.7 Nb 26.8 Ta 26.8)2AlC has a maximum compressive strength of 1628MPa at room temperature, a fracture strain of 1.79%, and a yield strength of 520MPa at 1200℃.

[0012] Furthermore, when M is Ti a V b Nb d Ta e When a = 29.7 at%, b = 16.7 at%, and d = e = 26.8 at%, the chemical formula of the MAX phase is (Ti 29.7 V 16.7 Nb 26.8 Ta 26.8 )2AlC has a maximum compressive strength of 1583MPa at room temperature, a fracture strain of 1.74%, and a yield strength of 457MPa at 1200℃.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned high-temperature, high-strength, high-entropy MAX phase material, which specifically includes the following steps:

[0014] S1) Weigh the raw material powder containing the required elements in an argon-protected glove box according to the designed composition ratio;

[0015] S2) The weighed raw material powder is ball-milled and mixed evenly to obtain a mixed powder;

[0016] S3) The ball-milled mixed powder is subjected to spark plasma sintering to obtain the high-temperature, high-strength, high-entropy MAX phase bulk material.

[0017] Furthermore, the raw material powder used for weighing is selected from TiC, Ti, ZrC, V, Nb, Ta, Al and graphite carbon powder with a purity of over 99.5%.

[0018] Furthermore, the ball mill rotation speed is 100-200 r / min, the ball milling time is 30-40 h, and the ball-to-material ratio is (1-5):1.

[0019] Furthermore, the discharge plasma sintering pressure is 40–60 MPa, the sintering temperature is 1300–1500 °C, and the holding time is 5–10 min.

[0020] A high-temperature, high-strength, high-entropy MAX phase bulk material is applied to the fabrication of high-temperature structural components.

[0021] In this invention, among the five elements dissolved at the M site, Zr has the largest atomic size and V has the smallest. By controlling the composition ratio of Zr and V, the sum of the atomic percentages of Zr and / or V is ≤16.7%, which helps to reduce the atomic size difference of the system. Referring to the Hume-Rothery criterion for solid solution design in alloys, the smaller the atomic size difference, the more conducive it is to the formation of single-phase solid solutions. Therefore, the high-temperature, high-strength, and high-entropy MAX material produced by this invention has a low impurity phase content, and the volume fraction of the 211-type MAX phase can account for more than 95%.

[0022] The beneficial effects of this invention are:

[0023] (1) The method for preparing high-temperature, high-strength, high-entropy MAX phase materials provided by the present invention uses elemental powder and carbide powder as raw materials, which is low in cost and simple and efficient.

[0024] (2) The high-temperature, high-strength, high-entropy MAX material prepared by the preparation method of the present invention has high purity and the volume fraction of the 211 type MAX phase is more than 95%.

[0025] (3) Compared with traditional MAX phase materials, it has higher strength and plasticity at both room temperature and high temperature, and has broad application prospects in high temperature fields. Attached Figure Description

[0026] Figure 1 The image shows the XRD pattern of Ti2AlC in Comparative Example 1.

[0027] Figure 2 The table shows the room temperature compressive stress-strain diagram of Ti2AlC in Comparative Example 1.

[0028] Figure 3 The figure shows the high-temperature compressive stress-strain diagram of Ti2AlC at 1200℃ in Comparative Example 1.

[0029] Figure 4 In Example 1 (TiZr) 0.3 V 0.3 XRD pattern of NbTa)2AlC.

[0030] Figure 5 In Example 1 (TiZr) 0.3 V 0.3 SEM image of the tissue structure morphology of NbTa)2AlC.

[0031] Figure 6 In Example 1 (TiZr) 0.3 V 0.3 NbTa)2AlC room temperature compressive stress-strain diagram.

[0032] Figure 7 In Example 1 (TiZr)0.3 V 0.3 High-temperature compressive stress-strain diagram of NbTa)2AlC at 1200℃.

[0033] Figure 8 In Example 2 (TiZr) 0.6 XRD pattern of NbTa)2AlC.

[0034] Figure 9 In Example 2 (TiZr) 0.6 SEM image of the tissue structure morphology of NbTa)2AlC.

[0035] Figure 10 In Example 2 (TiZr) 0.6 NbTa)2AlC room temperature compressive stress-strain diagram.

[0036] Figure 11 In Example 2 (TiZr) 0.6 High-temperature compressive stress-strain diagram of NbTa)2AlC at 1200℃. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific comparative examples and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0038] This invention discloses a high-temperature, high-strength, high-entropy MAX phase bulk material, with the molecular formula M2AX, where M is any combination of four or more of the five elements Ti, Zr, V, Nb, and Ta, the atomic percentage of each component in the M sublattice is between 5% and 35%, and the sum of the atomic percentages of Zr and V is less than or equal to 16.7%, A is Al, and X is C.

[0039] The high-temperature, high-strength, high-entropy MAX phase bulk material has high purity, with the volume fraction of the 211-type MAX phase not less than 95%.

[0040] The high-temperature, high-strength, high-entropy MAX phase bulk material exhibits excellent mechanical properties at both room temperature and high temperature. At room temperature, the maximum compressive strength exceeds 1500 MPa, the fracture strain exceeds 1.5%, and the yield strength exceeds 300 MPa at 1200℃, with no obvious strain softening phenomenon.

[0041] When M is Ti a Zr b V c Nb d Ta e When a = d = e and b = c = 8.3%, the chemical formula of this high-temperature, high-strength, high-entropy MAX phase is (TiZr).0.3 V 0.3 NbTa)2AlC has a maximum compressive strength of 1800 MPa at room temperature, a fracture strain of 2.03%, and a yield strength of 360 MPa at 1200℃.

[0042] When M is Ti a Zr b Nb d Ta e When a = d = e and b = 16.7%, the chemical formula of the MAX phase is (TiZr). 0.6 NbTa)2AlC has a maximum compressive strength of 1687 MPa at room temperature, a fracture strain of 1.84%, and a yield strength of 558 MPa at 1200℃.

[0043] When M is Ti a Zr b Nb d Ta e When a = 29.7%, b = 16.7%, and d = e = 26.8%, the chemical formula of the MAX phase is (Ti 29.7 Zr 16.7 Nb 26.8 Ta 26.8 )2AlC has a maximum compressive strength of 1628MPa at room temperature, a fracture strain of 1.79%, and a yield strength of 520MPa at 1200℃.

[0044] When M is Ti a V b Nb d Ta e When a = 29.7 at%, b = 16.7 at%, and d = e = 26.8 at%, the chemical formula of the MAX phase is (Ti 29.7 V 16.7 Nb 26.8 Ta 26.8 )2AlC has a maximum compressive strength of 1583MPa at room temperature, a fracture strain of 1.74%, and a yield strength of 457MPa at 1200℃.

[0045] Another object of the present invention is to provide a method for preparing the above-mentioned high-temperature, high-strength, high-entropy MAX phase material, which specifically includes the following steps:

[0046] Step 1: Weigh the raw material powder containing the required elements in an argon-protected glove box according to the designed composition ratio;

[0047] Step 2: Ball mill the weighed raw material powder to mix it evenly and obtain a mixed powder;

[0048] Step 3: Perform spark plasma sintering on the ball-milled mixed powder to obtain the high-temperature, high-strength, high-entropy MAX phase bulk material.

[0049] The raw material powder used for weighing is selected from TiC, Ti, ZrC, Hf, V, Nb, Ta, Cr, Mo, Al and graphite carbon powder with a purity of over 99.5%.

[0050] The ball milling speed is 100-200 r / min, the ball milling time is 30-40 h, and the ball-to-material ratio is (1-5):1.

[0051] The discharge plasma sintering pressure is 40–60 MPa, the sintering temperature is 1300–1500 °C, and the holding time is 5–10 min.

[0052] A high-temperature, high-strength, high-entropy MAX phase bulk material is applied to the fabrication of high-temperature structural components.

[0053] Comparative Example 1

[0054] Preparation and characterization of Ti2AlC materials:

[0055] (1) Raw material preparation: Weigh 21.205g TiC, 18.736g Ti, and 12.070g Al in an argon-protected glove box and put them into a vacuum ball mill jar with a ball-to-material ratio of (1-5):1. The stainless steel balls have a size of φ1-5mm.

[0056] (2) Mixing: Place the vacuum ball mill jar into the all-around planetary ball mill, rotate at 100 r / min, and mix for 30 h to 40 h.

[0057] (3) Sintering: Weigh out about 4g of the mixed powder and put it into a graphite mold with a diameter of 12mm. Use spark plasma sintering at a pressure of 50MPa and a sintering temperature of 1300℃ for 10min. After cooling, take it out of the mold.

[0058] (4) Material Phase Characterization and Mechanical Property Testing: The sintered sample was cut off by wire cutting to remove the portion of the surface bonded to the graphite carbon paper. The smooth surface was then sanded to 2000 grit. X-ray diffraction was used to identify the phase composition of the material. The surface was then polished, and the microstructure was characterized using scanning electron microscopy. A cylindrical sample with a height-to-diameter ratio of 2:1 was cut by wire cutting, and its surface was polished. The room temperature mechanical properties of the sample were tested using a universal testing machine, and the high temperature mechanical properties were tested using a Gleeble thermal simulation testing machine. The strain rate for both room temperature and high temperature mechanical property tests was 1.

[0059] ×10 -4 s -1 .

[0060] like Figure 1 The image shows the XRD pattern of the Ti2AlC material prepared above, indicating that its main phase is Ti2AlC, with only a small amount of Ti3AlC2. Figure 2 The figure shows the room temperature compressive stress-strain diagram of the Ti2AlC prepared above. From this, it can be seen that its room temperature compressive strength is 986 MPa and its fracture strain is 1.18%. Figure 3 The figure shows the high-temperature compressive stress-strain diagram of the Ti2AlC prepared above at 1200℃. It can be seen that its high-temperature yield strength is 156MPa and it exhibits obvious strain softening phenomenon.

[0061] Example 1

[0062] (TiZr 0.3 V 0.3 Preparation and characterization of NbTa2AlC materials:

[0063] (1) Raw material preparation: Weigh TiC: 6.907g, ZrC: 3.572g, V: 1.763g, Nb: 10.716g, Ta: 20.872g, Al: 5.882g, C: 0.568g in an argon-protected glove box, and put them into a vacuum ball milling jar with a ball-to-material ratio of (1~5):1. The stainless steel balls have a size of φ1~5mm.

[0064] (2) Mixing: Load the vacuum ball mill jar into the omnidirectional planetary ball mill, rotate at 100 r / min, and mix for 33 h;

[0065] (3) Sintering: Weigh out about 6g of the mixed powder and put it into a graphite mold with a diameter of 12mm. Use spark plasma sintering at a pressure of 50MPa and a sintering temperature of 1400℃ for 10min. After cooling, take it out of the mold.

[0066] (4) Material Structure and Microstructure Characterization: The sintered sample was cut off by wire cutting to remove the portion of the surface bonded to the graphite carbon paper. The smooth surface was then sanded to 2000 grit. X-ray diffraction was used to identify the phase composition of the material. The surface was then polished, and the microstructure was characterized using scanning electron microscopy. A cylindrical sample with a height-to-diameter ratio of 2:1 was cut by wire cutting, and its surface was polished. The room temperature mechanical properties of the sample were tested using a universal testing machine, and the high temperature mechanical properties were tested using a Gleeble thermal simulation testing machine. The strain rate for both room temperature and high temperature mechanical property tests was 1×10⁻⁶. -4 s -1 .

[0067] like Figure 4 As shown, this is the (TiZr) obtained above. 0.3V 0.3 The XRD pattern of NbTa)₂AlC material indicates that its main phase is M₂AlC. For example... Figure 5 As shown, this is the (TiZr) obtained above. 0.3 V 0.3 SEM images of the microstructure of NbTa)2AlC show that the synthesized sample has a uniform and dense microstructure, with a small amount of black phase being Al2O. 3， Statistical analysis shows that the Al2O3 phase volume fraction is only 3%, and the sample purity is as high as 97%. For example... Figure 6 As shown, this is the (TiZr) obtained above. 0.3 V 0.3 The room temperature compressive stress-strain diagram of NbTa₂AlC shows that its room temperature compressive strength is 1800 MPa and its fracture strain is 2.03%. Figure 7 As shown, this is the (TiZr) obtained above. 0.3 V 0.3 The high-temperature compressive stress-strain diagram of NbTa)2AlC at 1200℃ shows that its high-temperature yield strength is 360MPa and it exhibits obvious strain hardening.

[0068] Example 2

[0069] (TiZr 0.6 Preparation and characterization of NbTa2AlC materials:

[0070] (1) Raw material preparation: Weigh TiC: 6.719g, ZrC: 6.951g, Nb: 10.426g, Ta: 20.306g, Al: 5.723g, C: 0.148g in an argon-protected glove box, and put them into a vacuum ball milling jar with a ball-to-material ratio of (1~5):1. The stainless steel balls have a size of φ1~5mm.

[0071] (2) Mixing: Load the vacuum ball mill jar into the all-around planetary ball mill, rotate at 100 r / min, and mix for 40 h;

[0072] (3) Sintering: Weigh out about 6g of the mixed powder and put it into a graphite mold with a diameter of 12mm. Use spark plasma sintering at a pressure of 50MPa and a sintering temperature of 1450℃ for 10min. After cooling, take it out of the mold.

[0073] (4) Material Structure and Microstructure Characterization: The sintered sample was cut off by wire cutting to remove the portion of the surface bonded to the graphite carbon paper. The smooth surface was then sanded to 2000 grit. X-ray diffraction was used to identify the phase composition of the material. The surface was then polished, and the microstructure was characterized using scanning electron microscopy. A cylindrical sample with a height-to-diameter ratio of 2:1 was cut by wire cutting, and its surface was polished. The room temperature mechanical properties of the sample were tested using a universal testing machine, and the high temperature mechanical properties were tested using a Gleeble thermal simulation testing machine. The strain rate for both room temperature and high temperature mechanical property tests was 1×10⁻⁶. -4 s -1 .

[0074] like Figure 8 As shown, the (TiZr) prepared above 0.6 The XRD pattern of NbTa)₂AlC material indicates that its main phase is M₂AlC. For example... Figure 9 As shown, this is the (TiZr) obtained above. 0.6 SEM images of the microstructure of NbTa)₂AlC show that the synthesized sample has a uniform and dense microstructure, with a small amount of black phase being ZrO₂. Statistical analysis shows that the ZrO₂ phase accounts for only 2% of the volume, and the sample purity is as high as 98%. Figure 10 As shown, this is the (TiZr) obtained above. 0.6 The room temperature compressive stress-strain diagram of NbTa₂AlC shows that its room temperature compressive strength is 1687 MPa and its fracture strain is 1.84%. Figure 11 As shown, this is the (TiZr) obtained above. 0.6 The high-temperature compressive stress-strain diagram of NbTa)2AlC at 1200℃ shows that its high-temperature yield strength is 558MPa and no strain softening occurs.

[0075] Summary of results for each embodiment:

[0076]

[0077] The above provides a detailed description of a high-temperature, high-strength, high-entropy MAX phase bulk material, its preparation, and its application, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the methods and core ideas of this application; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0078] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0079] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0080] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0081] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A high-temperature, high-strength, high-entropy MAX phase bulk material, characterized in that, The molecular formula of the high-temperature, high-strength, high-entropy MAX phase bulk material is M2AX, and its chemical formula is (Ti 29.7 Zr 16.7 Nb 26.8 Ta 26.8 The high-temperature, high-strength, high-entropy MAX phase bulk material is of high purity, with a volume fraction of 211-type MAX phase of not less than 95%. Moreover, the prepared high-temperature, high-strength, high-entropy MAX material has excellent mechanical properties at both room temperature and high temperature, with a maximum compressive strength of 1628 MPa at room temperature, a fracture strain of 1.79%, and a yield strength of 520 MPa at 1200℃. The method for preparing the aforementioned high-temperature, high-strength, high-entropy MAX phase material specifically includes the following steps: S1) Weigh the raw material powder containing the required elements in an argon-protected glove box according to the designed composition ratio; S2) The weighed raw material powder is ball-milled and mixed evenly to obtain a mixed powder; S3) The ball-milled mixed powder is subjected to spark plasma sintering to obtain the high-temperature, high-strength, high-entropy MAX phase bulk material; The discharge plasma sintering pressure is 40~60MPa, the sintering temperature is 1300~1500℃, and the holding time is 5~10min.

2. The high-temperature, high-strength, high-entropy MAX phase bulk material according to claim 1, characterized in that, The ball milling process parameters are: rotation speed of 100~200 r / min, ball milling time of 30h~40h, and ball-to-material ratio of (1~5):

1.

3. The application of a high-temperature, high-strength, high-entropy MAX phase bulk material as described in claim 1 or 2 in the preparation of high-temperature structural components.

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