High-strength and high-toughness polycrystalline diamond compact rich in FCC phase high-entropy alloy

Abstract

The embodiment of the invention provides a high-strength and high-toughness polycrystalline diamond compact rich in FCC phase high-entropy alloy. The high-strength and high-toughness polycrystalline diamond compact comprises polycrystalline diamond and the high-entropy alloy. The high-entropy alloy includes a solid solution phase having a face-centered cubic crystal structure; the percentage of the difference between the lattice constant a1 of the solid solution phase and the lattice constant a2 of the polycrystalline diamond to the lattice constant a2 of the polycrystalline diamond is less than or equal to 5%; the high-entropy alloy comprises Al, Co, Cr, Fe and Ni; the high-entropy alloy comprises Al, Co, Cr, Fe and Ni; the atomic ratio of Al to Co to Cr to Fe to Ni is 1: 1: 1: 1: (2.0-2.2). The percentage of the difference between the lattice constant of the solid solution phase contained in the high-entropy alloy and the lattice constant of the polycrystalline diamond to the lattice constant of the polycrystalline diamond is less than or equal to 5%, so that the bonding strength between the polycrystalline diamond layer and the matrix layer in the obtained high-strength and high-toughness polycrystalline diamond compact is improved; the heat stability of the high-strength and high-toughness polycrystalline diamond compact is better.

Description

Technical Field

[0001] This application relates to the field of polycrystalline diamond composite material technology, and in particular to a high-strength and high-toughness polycrystalline diamond composite sheet rich in FCC phase high-entropy alloy. Background Technology

[0002] Polycrystalline diamond composite (PDC) teeth are composite materials made from diamond micropowder and a cemented carbide matrix (WC-Co) through high-temperature and high-pressure sintering. Structurally, they consist of a polycrystalline diamond layer (PCD) and a cemented carbide layer. The cemented carbide matrix typically consists of WC and Co, with Co used to enhance the bonding strength between the diamond and the cemented carbide. During the sintering process, the metallic Co in the cemented carbide matrix melts and penetrates into the diamond powder, ultimately forming a bonded polycrystalline diamond layer and a cemented carbide layer. The resulting polycrystalline diamond composite teeth exhibit high hardness and excellent wear resistance, and are widely used in industries such as oil drilling, geological exploration, coalfield drilling bits, and machining tools. In machining, they are primarily used for the finishing of materials such as aluminum alloys, copper alloys, titanium alloys, and wood.

[0003] However, in the existing polycrystalline diamond (PCD) composite sheet preparation process, carbides easily form at the interface between diamond and Co, leading to abnormal grain growth and thickening of the black edge layer, resulting in reduced mechanical properties of the obtained PCD-Co composite sheet. Moreover, the insufficient penetration of the binder Co into the diamond during sintering results in a polycrystalline diamond layer with numerous pores, leading to insufficient bonding strength and thermal stability between the PCD layer and the cemented carbide layer in the obtained PCD-Co composite sheet.

[0004] Therefore, there is an urgent need to develop a high-strength and high-toughness polycrystalline diamond composite sheet with high bonding strength and good thermal stability to solve the problems of low bonding strength and poor thermal stability of existing polycrystalline diamond composite sheets. Summary of the Invention

[0005] This application provides a high-strength, high-toughness polycrystalline diamond composite sheet rich in FCC phase high-entropy alloy, which can improve the bonding strength and thermal stability of the high-strength, high-toughness polycrystalline diamond composite sheet.

[0006] In a first aspect, embodiments of this application provide a high-strength, high-toughness polycrystalline diamond composite sheet, comprising polycrystalline diamond and a high-entropy alloy;

[0007] The high-entropy alloy contains a solid solution phase with a face-centered cubic crystal structure.

[0008] The absolute value of the difference between the lattice constant a1 of the solid solution phase and the lattice constant a2 of the polycrystalline diamond is less than or equal to 5% of the lattice constant a2 of the polycrystalline diamond.

[0009] The high-entropy alloy comprises Al, Co, Cr, Fe, and Ni;

[0010] The atomic ratio of Al, Co, Cr, Fe and Ni is 1:1:1:1:(20-2.2).

[0011] In one possible implementation, the lattice constant a1 of the solid solution phase satisfies 3.391 Å ≤ a1 ≤ 3.749 Å;

[0012] And / or, the solid solution phase accounts for a volume fraction of 50% or more of the high-entropy alloy.

[0013] In one possible implementation, the porosity of the high-strength, high-toughness polycrystalline diamond composite sheet is less than or equal to 0.5%.

[0014] And / or, the abnormal grain growth of the diamond is less than or equal to 20%.

[0015] In one possible implementation, the high-strength, high-toughness polycrystalline diamond composite sheet further includes carbides;

[0016] Preferably, the abnormal grain growth of the carbide is less than or equal to 20%.

[0017] Secondly, embodiments of this application provide a method for preparing the above-mentioned high-strength and high-toughness polycrystalline diamond composite sheet, comprising: laying diamond on the surface of a substrate containing the high-entropy alloy, and then sintering it to obtain the high-strength and high-toughness polycrystalline diamond composite sheet.

[0018] In one possible implementation, the high-entropy alloy has a mass fraction of 10%-18% in the matrix;

[0019] And / or, the D50 particle size of the diamond is 1μm-30μm;

[0020] And / or, the diamond layer thickness is 0.5mm-4mm.

[0021] In one possible implementation, the diamond comprises two or more diamonds with a D50 size.

[0022] Preferably, the diamond includes diamonds with three different diameters: d1, d2, and d3, where d1 satisfies 1μm≤d1≤5μm, d2 satisfies 5μm<d2≤10μm, and d3 satisfies 10μm<d3≤20μm.

[0023] In one possible implementation, the sintering includes:

[0024] A matrix with diamond deposited on its surface is subjected to a first heat preservation treatment, a second heat preservation treatment, a pressure holding and cooling treatment, and a pressure release treatment at 6GPa-8.5GPa to obtain the high-strength and high-toughness polycrystalline diamond composite sheet; wherein the temperature of the first heat preservation treatment is lower than the temperature of the second heat preservation treatment.

[0025] In one possible implementation, the temperature of the first heat preservation treatment is 1420℃-1480℃, and the heat preservation time is 5min-10min.

[0026] And / or, the temperature of the second heat preservation treatment is 1550℃-1620℃, and the heat preservation time is 20min-90min;

[0027] And / or, the cooling rate of the pressure-holding and cooling process is 10℃ / min-20℃ / min;

[0028] And / or, the pressure relief rate is 1 GPa / min - 2 GPa / min.

[0029] In one possible implementation, the matrix further includes carbides;

[0030] Preferably, the carbide includes at least one of tungsten carbide, titanium carbide, and chromium carbide.

[0031] Preferably, the method for preparing the matrix includes: hot isostatic pressing of raw materials containing the high-entropy alloy and the carbide at 1200℃-1600℃ and 50MPa-70MPa to obtain the matrix.

[0032] Thirdly, embodiments of this application provide an alloy material, including the above-mentioned high-strength and high-toughness polycrystalline diamond composite sheet or the high-strength and high-toughness polycrystalline diamond composite sheet prepared by the above-mentioned preparation method.

[0033] This application provides a high-strength, high-toughness polycrystalline diamond composite sheet rich in FCC phase high-entropy alloy. By selecting a high-entropy alloy containing a face-centered cubic crystal structure solid solution phase as a component, the solid solution phase with this specific structure has a lattice constant that is not much different from that of polycrystalline diamond, thereby reducing the mismatch between the two and achieving the effect of improving the bonding strength and thermal stability of polycrystalline diamond and high-entropy alloy, resulting in a high-strength, high-toughness polycrystalline diamond composite sheet with higher bending strength and hardness. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0035] Figure 1A schematic diagram of the grain structure at the interface between the diamond layer and the hard alloy matrix containing high-entropy alloy in the high-strength and high-toughness polycrystalline diamond composite sheet provided in this application.

[0036] Figure 2 This is a schematic diagram of the grain structure at the interface between the diamond layer and WC-Co cemented carbide in a commercially available polycrystalline diamond composite sheet.

[0037] Figure 3 A schematic diagram of the microstructure and elemental distribution of the high-strength, high-toughness polycrystalline diamond composite sheet provided in this application;

[0038] Figure 4 A schematic diagram of the surface appearance of the high-strength and high-toughness polycrystalline diamond composite sheet provided in this application after thermal expansion;

[0039] Figure 5 This is a schematic diagram of the surface appearance of a cobalt-based polycrystalline diamond composite sheet after thermal expansion.

[0040] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0042] First, let me explain the terms used in this application:

[0043] High-entropy alloys refer to a new type of metallic material composed of multiple (usually five or more) main elements in equal or near-equal atomic ratios.

[0044] Lattice constant: also known as the lattice constant, is a physical quantity that describes the basic dimensions of the lattice, an abstract geometric framework in a crystal. It refers to the length of the unit cell or edge of the unit cell in the lattice. For the cubic crystal system, the unit cell is a cube, and only one lattice constant a is needed to describe it, because the three edges are of equal length (a=b=c) and the included angle is 90°.

[0045] Solid solution phase: refers to a homogeneous solid phase formed by mixing different components at the atomic scale while maintaining a single crystal structure.

[0046] In the prior art, cobalt-based polycrystalline diamond composite sheets (Co / PCD) prepared using traditional cobalt-based binders have technical problems such as low bonding strength between diamond and binder, and low mechanical strength and thermal stability of polycrystalline diamond composite sheets.

[0047] The method for preparing high-strength and high-toughness polycrystalline diamond composite sheets provided in this application solves the technical problem of low bonding strength and thermal stability between the hard alloy matrix and the bonding layer in high-strength and high-toughness polycrystalline diamond composite sheets by using a high-entropy alloy with a solid solution phase containing a specific lattice constant as the matrix.

[0048] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0049] This application provides a high-strength, high-toughness polycrystalline diamond composite sheet (HEA / PCD), comprising polycrystalline diamond and a high-entropy alloy. The high-entropy alloy contains a solid solution phase with a face-centered cubic crystal structure. The absolute value of the difference between the lattice constant a1 of the solid solution phase and the lattice constant a2 of the polycrystalline diamond is less than or equal to 5% of the lattice constant a2 of the polycrystalline diamond. The high-entropy alloy comprises Al, Co, Cr, Fe, and Ni. The atomic ratio of Al, Co, Cr, Fe, and Ni is 1:1:1:1:(20-2.2).

[0050] High-entropy alloys (HEAs) are composed of multiple main elements. Their extremely high configurational entropy allows them to maintain a stable single-phase solid solution structure even at high temperatures, with slow atomic diffusion. Therefore, at the sintering temperature of polycrystalline diamond (PCD) (1400℃-1600℃) and in subsequent high-temperature operating environments, HEAs are less prone to phase transformation, grain coarsening, or violent and harmful reactions with diamond. Simultaneously, the slow diffusion characteristics of HEAs effectively inhibit the transformation of diamond into graphite or the formation of excessive brittle carbides. They form a thinner, more stable carbide layer on the diamond surface, achieving strong adhesion without excessively damaging the diamond, thus maintaining its ultra-high hardness. In this application, by designing the elements in the high-entropy alloy, the absolute value of the difference between the lattice constant a1 of the solid solution phase in the high-entropy alloy and the lattice constant a2 of diamond is controlled to be less than or equal to 5% of the lattice constant a2 of diamond. This allows the carbon atoms on the diamond surface to achieve ideal bonding distances and angles with the active element atoms in the high-entropy alloy, reducing interface defects, eliminating harmful stresses, and ensuring the stability of the interface between the two at high temperatures. Moreover, the low-defect, strong-bonded interface formed between diamond and the high-entropy alloy effectively blocks the direct contact and diffusion of catalytic elements in the alloy with diamond carbon atoms, significantly delaying graphitization and brittle phase growth at high temperatures, thereby improving the thermal stability of the resulting high-strength, high-toughness polycrystalline diamond composite sheet (HEA / PCD).

[0051] In this application, the lattice constant a1 of the solid solution phase and the lattice constant a2 of diamond can be obtained by methods commonly used in the art. Specifically, X-ray diffraction can be used to scan the high-entropy alloy and diamond to obtain the corresponding diffraction patterns (intensity vs. 2θ), determine the position of each diffraction peak (2θ value), and assign each diffraction peak to the corresponding crystal plane (h, k, l). For the cubic crystal system, according to formula 1 / d... 2 =(h 2 +k 2 +l 2 ) / a 2 By substituting the d-values ​​and (h, k, l) of multiple peaks, the lattice constant can be accurately calculated through linear fitting or the least squares method.

[0052] It should be understood that diamond, as a material with a known structure, has a lattice constant a2 = 3.57 Å.

[0053] In this application, the high-entropy alloy includes Al, Co, Cr, Fe, and Ni.

[0054] In this high-entropy alloy, Co, Fe, and Ni can form stable carbides or solid solutions with carbon in diamond, enhancing the interfacial chemical bonding between the high-entropy alloy and diamond. Ni is a strong FCC stabilizer, effectively reducing stacking fault energy and promoting dislocation slip and nanofiber twinning, thus maintaining excellent ductility while improving strength. Furthermore, Ni promotes the formation of a dense and stable passivation film (especially a Cr2O3-rich film) on the surface of the high-entropy alloy, improving its resistance to pitting corrosion in acidic or chloride environments. Cr readily forms strong carbides such as Cr3C2 and Cr7C3, enhancing interfacial bonding. The presence of Al lowers the melting point and viscosity of the high-entropy alloy, promoting the wetting of the diamond surface by the liquid alloy. The Al, Co, Cr, Fe, and Ni contained in high-entropy alloys can form multilayer carbide transition zones (such as Co-Cr-C, Fe-Ni-C composite carbides, etc.) with the diamond surface during high-temperature sintering. This not only reduces interfacial stress concentration and enhances the mechanical anchoring effect, but also improves the thermal stability of the resulting high-strength, high-toughness polycrystalline diamond composite sheet. During sintering or subsequent heat treatment, the alloy may also precipitate nanoscale carbides (such as M7C3, M...). 23 These precipitates (such as C6) can pin the interface, hinder dislocation movement, and improve the shear resistance of the interface between high-entropy alloys and diamond.

[0055] Furthermore, by controlling the atomic percentage of Ni in high-entropy alloys, dislocation slip can be utilized to provide plasticity for high-strength, high-toughness polycrystalline diamond composite sheets, stimulating the formation of nanotwins. This "twin-induced plasticity" effect can simultaneously and significantly improve the strength and work hardening capacity of high-entropy alloys. Specifically, when the chemical formula of the high-entropy alloy is AlCoCrFeNi... 2.1 Upon solidification, it forms a layered eutectic structure of BCC (rich in Al and Ni phases) + FCC (rich in Co, Cr, and Fe phases). This two-phase structure can buffer the thermal expansion mismatch stress between diamond and the high-entropy alloy as the binder phase through the synergistic effect of plastic deformation (FCC phase) and strength support (BCC phase), thus inhibiting the initiation of interfacial cracks. Moreover, such a two-phase eutectic structure can maintain the stability of the structure at high temperatures (the eutectic point composition is not prone to phase transformation), reducing volume changes or interfacial delamination caused by phase transformation. At the same time, the FCC phase provides high-temperature toughness, and the BCC phase maintains high-temperature strength, synergistically maintaining the integrity of the interface during thermal cycling, thereby improving the thermal stability of the resulting high-strength and high-toughness polycrystalline diamond composite sheet.

[0056] For example, the number of Ni atoms in a high-entropy alloy can be a range of 2.0, 2.1, 2.2, or any two of them.

[0057] In some specific implementations, the lattice constant a1 of the solid solution phase satisfies 3.391Å≤a1≤3.749Å.

[0058] To achieve a higher degree of compatibility between the crystal structures of high-entropy alloys and diamond, this application selects the lattice constant a1 of the solid solution phase in the high-entropy alloy to be between 3.391Å ≤ a1 ≤ 3.749Å, so that the mismatch between the lattice constant of the solid solution phase and the lattice constant of diamond is less than 5%. This forms a stronger and more stable bonding interface between diamond and high-entropy alloys, further optimizing the microstructure, improving the thermal stability of the high-strength and high-toughness polycrystalline diamond composite sheet, and enhancing the overall performance of the material.

[0059] In some specific embodiments, the solid solution phase accounts for a volume fraction of 50% or more in the high-entropy alloy.

[0060] Based on first-principles calculations, the bonding strength between diamond and a solid solution with a face-centered cubic (FCC) phase is higher than that between cobalt and diamond, while the bonding strength between diamond and a body-centered cubic (BCC) phase is comparable to that between cobalt and BCC. Therefore, by further controlling the volume fraction of the FCC phase solid solution in the high-entropy alloy to be greater than or equal to 50%, the interfacial strength between diamond and the high-entropy alloy can be further improved.

[0061] In this application, the volume fraction of the solid solution phase with a face-centered cubic crystal structure in a high-entropy alloy can be measured using X-ray diffraction. The volume fraction of the target solid solution phase is determined by analyzing the intensity of diffraction peaks of different phases in the obtained XRD diffraction pattern. Specifically, the XRD pattern is first calibrated to identify all existing phases (e.g., FCC phase, BCC phase, intermetallic compound phase, etc.); then, one or more characteristic diffraction peaks with high intensity and no overlap interference are selected for each phase; for a multiphase mixture containing n phases, the volume fraction V of each phase j is determined. j V can be estimated using the following formula: j =(I j / R j ) / Σ(I i / R i ), where: I j R is the integrated intensity of a certain diffraction peak of phase j. j The intensity factor of phase j is a theoretically calculated factor, which is related to the crystal structure, crystal plane indices, atomic types and positions, etc. This factor can be calculated using crystallographic databases or software (such as Jade, MAUD). Finally, Rietveld refinement is used. By fitting the entire experimental XRD pattern to a calculated pattern based on a crystal structure model, the model parameters (including lattice constant, atomic occupancy, phase ratio, etc.) are continuously refined using the least squares method, thereby directly calculating the weight fraction of each phase. When the density is close, it can be directly approximated as the volume fraction.

[0062] In some specific implementations, the porosity of the high-strength, high-toughness polycrystalline diamond composite sheet is less than or equal to 0.5%.

[0063] By selecting the diamond and high-entropy alloy used to prepare high-strength and high-toughness polycrystalline diamond composite sheets as described above, the high-entropy alloy can effectively "wet" the diamond surface in the liquid state. Under the action of capillary force, it spontaneously penetrates and fills the gaps in the diamond particles, expelling gas and reducing porosity. The porosity of the resulting high-strength and high-toughness polycrystalline diamond composite sheet can reach less than or equal to 5%.

[0064] In some specific embodiments, the high-strength and high-toughness polycrystalline diamond composite sheet includes an interface black edge layer, the thickness of which is less than or equal to 3 μm.

[0065] Under high temperature and pressure, metallic elements (such as Co, Fe, Ni, etc.) in the binder phase act as strong catalysts for diamond graphitization. Carbon atoms on the surface of diamond particles undergo graphitization at high temperatures, and the graphite dissolves into the liquid binder phase. This graphite, catalyzed by the liquid metal, transforms into more stable graphite under high temperature and pressure. At the interface between the diamond layer and the cemented carbide layer, the abundant carbon content after diamond graphitization easily leads to the growth of tungsten carbide in the cemented carbide, which then forms cobalt carbides with the cobalt in the cemented carbide, resulting in larger carbide particles at the interface.

[0066] In this application, by selecting a high-entropy alloy with a specific solid solution phase as the binder phase and preparing a high-strength and high-toughness polycrystalline diamond composite sheet together with diamond, the high degree of matching of the crystal structures of the two and the fact that the high-entropy alloy does not easily form carbides result in a small amount of carbon phase precipitation. Ultimately, there are no abnormally grown carbide particles at the interface of the obtained high-strength and high-toughness polycrystalline diamond composite sheet.

[0067] In some specific implementations, the abnormal growth degree of diamond grains is less than or equal to 20%.

[0068] In some specific implementations, the abnormal growth degree of the carbide grains is less than or equal to 20%.

[0069] like Figure 1 As shown, in the high-strength, high-toughness polycrystalline diamond composite sheet prepared by using a high-entropy alloy as a binder and diamond together, there is no abnormal grain growth at the interface between the high-entropy alloy and diamond. Figure 2 In the commercially available polycrystalline diamond composite sheets shown, cobalt is used as a binder, and a large number of abnormal grain growth phenomena occur at the interface between cobalt and diamond. Therefore, the high-strength, high-toughness polycrystalline diamond composite sheets prepared in this application using the aforementioned high-entropy alloy as a binder have a more dense and uniform microstructure.

[0070] The high-strength and high-toughness polycrystalline diamond composite sheet provided in this application is prepared by selecting a high-entropy alloy containing a solid solution phase with a face-centered cubic crystal structure as the matrix to prepare polycrystalline diamond, and controlling the lattice constant mismatch between the matrix and diamond to be less than or equal to 5%, thereby improving the internal bonding strength and thermal stability of the high-strength and high-toughness polycrystalline diamond composite sheet.

[0071] like Figure 3 As shown, the high-strength, high-toughness polycrystalline diamond composite sheet provided in this embodiment contains Fe, Co, Al, Cr, and Ni in a relatively uniform distribution morphology. Furthermore, as... Figure 4 , Figure 5 As shown, the high-strength and high-toughness polycrystalline diamond composite sheet provided in this application did not develop internal cracks after thermal expansion treatment, while commercially available polycrystalline diamond composite sheets showed more obvious internal cracks. It can be seen that the high-strength and high-toughness polycrystalline diamond composite sheet prepared in this application has better thermal stability.

[0072] This application also provides a method for preparing the above-mentioned high-strength and high-toughness polycrystalline diamond composite sheet, comprising: laying diamond on the surface of a substrate containing a high-entropy alloy, and then sintering it to obtain a high-strength and high-toughness polycrystalline diamond composite sheet.

[0073] In some specific implementations, the mass fraction of the high-entropy alloy in the matrix is ​​10%-18%.

[0074] During the preparation process, by controlling the mass ratio of high-entropy alloy in the matrix to 10%-18%, the interfacial penetration between the binder phase and the matrix is ​​ensured to balance the density of the composite material, thereby obtaining a high-strength and high-toughness polycrystalline diamond composite sheet with high bonding strength and good thermal stability.

[0075] For example, the mass fraction of the high-entropy alloy in the matrix can be a range of 10%, 11%, 12%, 13%, 14%, 15%, 18%, or any combination thereof.

[0076] In some specific implementations, the D50 particle size of the diamond is 1μm-30μm.

[0077] To improve the density of high-strength and high-toughness polycrystalline diamond composite sheets, the diamonds used can be made to form a bimodal or higher particle size distribution. Small-diameter diamonds are used to fill the gaps between large-diameter particles, forming a denser skeletal structure. At the same time, the large-diameter particles provide the main wear resistance, ultimately optimizing the diamond packing density and helping to reduce the porosity of the high-strength and high-toughness polycrystalline diamond composite sheets.

[0078] In some specific embodiments, the diamond may include diamonds with three different diameters: d1, d2, and d3, where d1 satisfies 1μm≤d1≤5μm, d2 satisfies 5μm<d2≤10μm, and d3 satisfies 10μm<d3≤20μm.

[0079] Experimental data show that when a three-peak distribution is adopted, the porosity of high-strength and high-toughness polycrystalline diamond composite sheets can be reduced to less than or equal to 5%, the hardness can be increased by 25%, and the bending strength can be increased by 18%.

[0080] For example, the d1 grain size in the diamond can be a range of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or any combination thereof; the d2 grain size can be a range of 5.5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any combination thereof; and the d3 grain size can be a range of 10.5 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or any combination thereof.

[0081] In some specific implementations, the diamond layup thickness is 0.5mm-4mm.

[0082] The thickness of the diamond layer varies depending on the application. For example, oil drilling tools require a thicker PCD layer, so the diamond layer thickness can be 3mm-4mm during the manufacturing process, while machining tools use a thickness of 0.5mm-1.5mm.

[0083] For example, the diamond layup thickness can be a range of 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, or any combination thereof.

[0084] In some specific embodiments, sintering includes: subjecting a matrix with diamond deposited on its surface to a first heat preservation treatment, a second heat preservation treatment, a pressure holding and cooling treatment, and a pressure release treatment at 7.5 GPa-8.5 GPa in sequence to obtain a high-strength and high-toughness polycrystalline diamond composite sheet; wherein the temperature of the first heat preservation treatment is lower than the temperature of the second heat preservation treatment.

[0085] This implementation method optimizes the penetration of the binder phase and the growth of diamond particles through a segmented heating sintering process under high pressure, thereby obtaining a high-strength and high-toughness polycrystalline diamond composite sheet with high bonding strength and good thermal stability.

[0086] In some specific implementations, the temperature of the first heat preservation treatment is 1420℃-1480℃, and the heat preservation time is 5min-10min.

[0087] By controlling the temperature and time of the first heat preservation treatment, on the one hand, the gas and impurities in the material can have sufficient time to slowly diffuse and be released through the initial gaps between the powder particles, purifying the subsequent diamond-diamond interface and diamond-high entropy alloy interface. On the other hand, it allows the binder phase to undergo a preliminary and mild interfacial reaction with diamond, forming a diffusion barrier layer, which slows down the excessive dissolution and graphitization of carbon into the binder phase in the subsequent high-temperature stage.

[0088] For example, the temperature of the first heat preservation treatment can be a range of 1420°C, 1430°C, 1440°C, 1450°C, 1460°C, 1470°C, 1480°C or any combination thereof; the heat preservation time can be a range of 5 min, 6 min, 7 min, 8 min, 9 min, 10 min or any combination thereof.

[0089] In some specific implementations, the temperature of the second heat preservation treatment is 1550℃-1620℃, and the heat preservation time is 20min-90min.

[0090] By controlling the temperature of the second heat treatment within the above range, sufficient energy can be provided for atomic diffusion, dislocation movement and mass migration, promoting mechanisms such as plastic flow and diffusion creep, enabling the material to flow into and fill the remaining pores; a certain heat treatment time ensures sufficient densification while inhibiting abnormal grain growth.

[0091] For example, the temperature of the second heat preservation treatment can be a range of 1550°C, 1560°C, 1570°C, 1580°C, 1590°C, 1600°C, 1610°C, 1620°C or any combination thereof; the heat preservation time can be a range of 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min or any combination thereof.

[0092] In some specific implementations, the cooling rate during pressure holding and cooling is 10℃ / min-20℃ / min.

[0093] After the second heat preservation treatment, by controlling the cooling rate during the pressure holding and cooling process, cracks caused by thermal stress inside the material can be avoided, which is conducive to obtaining a more dense high-strength and high-toughness polycrystalline diamond composite sheet.

[0094] For example, the cooling rate of the pressure holding and cooling can be a range of 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, 15℃ / min, 16℃ / min, 17℃ / min, 18℃ / min, 19℃ / min, 20℃ / min or any combination thereof.

[0095] In some specific implementations, the depressurization rate is 1 GPa / min to 2 GPa / min.

[0096] After holding the pressure and cooling down, the system is depressurized to atmospheric pressure. In order to allow the material to release internal stress smoothly, fully relax the microstructure and maintain the metastable phase, this application further controls the depressurization rate to 1 GPa / min-2 GPa / min to obtain a high-strength and high-toughness polycrystalline diamond composite sheet with a more complete structure.

[0097] For example, the pressure relief rate can be a range of 1 GPa / min, 1.1 GPa / min, 1.2 GPa / min, 1.3 GPa / min, 1.4 GPa / min, 1.5 GPa / min, 1.6 GPa / min, 1.7 GPa / min, 1.8 GPa / min, 1.9 GPa / min, 2 GPa / min, or any combination thereof.

[0098] In some specific embodiments, the matrix further includes carbides; preferably, the carbides include at least one of tungsten carbide, titanium carbide, and chromium carbide.

[0099] This implementation optimizes the matching of thermal expansion coefficients between the matrix and diamond by adding carbides to the matrix, thereby increasing the thermal failure temperature of the high-strength, high-toughness polycrystalline diamond composite sheet to 750°C. Carbides, as a hard phase, enhance the matrix strength, while their low thermal expansion coefficient (e.g., WC of 4.5 × 10⁻⁶) provides additional thermal expansion. -6 / K) and high-entropy alloys (approximately 10 × 10) -6 The gradient structure formed by the K-axis helps to alleviate the thermal stress inside the material.

[0100] In some specific embodiments, the matrix preparation method includes: hot isostatic pressing of raw materials containing high-entropy alloys and carbides at 1200℃-1600℃ and 50MPa-70MPa to obtain the matrix.

[0101] The matrix is ​​prepared using hot isostatic pressing (1200℃-1600℃, 50MPa-70MPa) to ensure uniform distribution of tungsten carbide and high-entropy alloy. By controlling the temperature and pressure of hot isostatic pressing, interdiffusion of elements between the high-entropy alloy and the carbide is promoted, which may form a thin and continuous solid solution or reaction layer at the interface, thereby achieving metallurgical bonding.

[0102] In some embodiments, the high-entropy alloy used can be a powder with a particle size of 10 μm-15 μm. Specifically, the particle size of the high-entropy alloy powder can be a range of 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any combination thereof.

[0103] In some other embodiments, the particle size of the carbide used may be 1 μm to 10 μm. Specifically, the particle size of the carbide may be a range of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any combination thereof.

[0104] In this embodiment, controlling the state and grain size of the high-entropy alloy used not only improves the interfacial strength between the matrix and diamond, but also prevents crack propagation through the "pinning" effect, thereby enhancing the toughness of the high-strength, high-toughness polycrystalline diamond composite sheet. Controlling the grain size of the carbides helps form a continuous, uniform carbide layer, effectively transferring loads and alleviating stress caused by the mismatch in thermal expansion coefficients, thus balancing the hardness and toughness of the high-strength, high-toughness polycrystalline diamond composite sheet.

[0105] The method for preparing high-strength and high-toughness polycrystalline diamond composite sheets provided in this application improves the bonding strength between the matrix and diamond and the overall thermal stability of the high-strength and high-toughness polycrystalline diamond composite sheets by laying diamond on the surface of a matrix containing a high-entropy alloy and then sintering it.

[0106] This application also provides an alloy material, including the above-mentioned high-strength and high-toughness polycrystalline diamond composite sheet or the high-strength and high-toughness polycrystalline diamond composite sheet prepared by the above-mentioned preparation method.

[0107] The following specific implementation will further illustrate the technical solution of this application.

[0108] Example 1

[0109] Matrix preparation: High-entropy alloy AlCoCrFeNi 2.1 (The volume fraction of the FCC phase is 55%, and the lattice constant of the FCC phase is a1=3.57nm) and tungsten carbide (WC) are mixed at a mass ratio of 13:87 and then subjected to hot isostatic pressing sintering at 1400℃ and 60MPa to obtain the HEA-WC matrix.

[0110] Diamond deposition: Diamonds with a lattice constant a2 = 3.57 Å are deposited on the HEA-WC matrix to a thickness of 3 mm; wherein, by mass percentage, the diamonds comprise 5% diamonds with D50 = 5 μm, 65% diamonds with D50 = 10 μm, and 30% diamonds with D50 = 20 μm.

[0111] Sintering: The diamond-coated HEA-WC matrix was heated to 1420℃ and held for 5 minutes at 7.5 GPa, and then heated to 1550℃ and held for 20 minutes.

[0112] Cooling and depressurization: After sintering is completed, the obtained material is cooled from 7.5 GPa to 300°C, and then the pressure is released to atmospheric pressure to obtain a high-strength and high-toughness polycrystalline diamond composite sheet.

[0113] Example 2

[0114] A high-strength and high-toughness polycrystalline diamond composite sheet is prepared in a similar manner to that in Example 1, except that the volume fraction of the FCC phase in the high-entropy alloy is 68%.

[0115] Example 3

[0116] A high-strength and high-toughness polycrystalline diamond composite sheet is prepared in a similar manner to that in Example 1, except that the volume fraction of the FCC phase in the high-entropy alloy is 100%.

[0117] Example 4

[0118] A high-strength, high-toughness polycrystalline diamond composite sheet is prepared using a method similar to that of Example 1, except that it incorporates a high-entropy alloy AlCoCrFeNi. 2.1 The mass ratio of WC to WC is 9:91.

[0119] Example 5

[0120] A high-strength, high-toughness polycrystalline diamond composite sheet is prepared using a method similar to that of Example 1, except that it incorporates a high-entropy alloy AlCoCrFeNi. 2.1 The mass ratio of WC to WC is 10:90.

[0121] Example 6

[0122] A high-strength, high-toughness polycrystalline diamond composite sheet is prepared using a method similar to that of Example 1, except that it incorporates a high-entropy alloy AlCoCrFeNi. 2.1 The mass ratio of WC to WC is 16:84.

[0123] Example 7

[0124] A high-strength, high-toughness polycrystalline diamond composite sheet is prepared using a method similar to that of Example 1, except that it incorporates a high-entropy alloy AlCoCrFeNi. 2.1 The mass ratio of WC to WC is 18:82.

[0125] Example 8

[0126] A diamond composite material, prepared by a method similar to that of Example 1, differs in that it uses a high-entropy alloy AlCoCrFeNi. 2.1 The mass ratio of WC to WC is 20:80.

[0127] Comparative Example 1

[0128] A high-strength and high-toughness polycrystalline diamond composite sheet is prepared in a similar manner to that in Example 1, except that the percentage difference between the lattice constant a1=3.771nm of the FCC phase and the lattice constant a2=3.57nm of diamond in the high-entropy alloy is 5.6%.

[0129] Comparative Example 2

[0130] A commercially available polycrystalline diamond composite sheet (Co / PCD) was purchased from Zigong Cemented Carbide Co., Ltd.

[0131] Comparative Example 3

[0132] A high-strength and high-toughness polycrystalline diamond composite sheet is prepared in a similar manner to that in Example 1, except that the high-entropy alloy used is AlCrNbSiTiBN.

[0133] Comparative Example 4

[0134] A high-strength and high-toughness polycrystalline diamond composite sheet is prepared in a similar manner to that in Example 1, except that the high-entropy alloy used is FeCoCrNiB0.15.

[0135] Comparative Example 5

[0136] A high-strength and high-toughness polycrystalline diamond composite sheet is prepared in a similar manner to that in Example 1, except that the high-entropy alloy used is (CoCrFeNiMn)90Al10.

[0137] The following performance tests were performed on the materials of Examples 1-8 and Comparative Examples 1-5:

[0138] Bending strength: Tested according to the three-point bending method in GB / T 6569-2006 "Test Method for Bending Strength of Fine Ceramics".

[0139] Hardness: Tested in accordance with T / CMTBA 2006-2024 "Technical Requirements for Diamond Composite Sheets for Oil and Gas Drilling".

[0140] Abnormal grain growth: Similar to interface observation, metallographic samples were prepared, and the size of diamond grains at the diamond-matrix interface and the size of carbide grains in the matrix were measured using image analysis software under a Thermo Fisher Apreo2 ultra-high resolution field emission scanning electron microscope. The difference between the current grain size and the original diamond and carbide grain sizes was calculated, and then the ratio of each difference to the original diamond and carbide grain sizes was calculated to obtain the abnormal grain growth.

[0141] Porosity: Similar to interface observation, metallographic samples were prepared, and the pores were counted and their area was statistically analyzed using image analysis software under a Thermo Fisher Scientific Apreo2 ultra-high resolution field emission scanning electron microscope. The area porosity was calculated and approximated as the volume porosity.

[0142] Thermal expansion coefficient and thermal failure temperature: Tests were conducted according to GB / T 4339-2008 "Determination of Thermal Expansion Characteristic Parameters of Metallic Materials". High-strength, high-toughness polycrystalline diamond composite sheets were placed in a heating furnace and heated, with their diameter changes measured in real time. The diameter increased with rising temperature, and cracks even formed. A sudden change in diameter occurred when cracks formed. By comparing the diameter change pattern and the temperature at which the diameter abruptly changed, the thermal failure temperature of the high-strength, high-toughness polycrystalline diamond composite sheet can be evaluated.

[0143] Wear area: Tested according to JB / T 3235 "Method for Determining Wear Ratio of Polycrystalline Diamond".

[0144] The test results are detailed in Tables 1-1 and 1-2. Figure 4 , Figure 5 .

[0145] Table 1

[0146]

[0147] Table 1-2

[0148]

[0149] As can be seen from the data in Tables 1-1 and 1-2, the high-strength and high-toughness polycrystalline diamond composite sheet provided in this application has excellent bending strength, hardness and wear resistance, and its coefficient of thermal expansion is low, resulting in a high thermal failure temperature.

[0150] Compared with Comparative Example 1, the polycrystalline high-entropy alloy of Example 1 exhibits superior flexural strength, hardness, wear resistance, and high-temperature resistance. This indicates that controlling the mismatch between the lattice constant of the FCC phase and the lattice constant of diamond in the high-entropy alloy used to within 5% is beneficial for obtaining high-strength and high-toughness polycrystalline diamond composite sheets with excellent mechanical properties and high-temperature resistance.

[0151] Compared with Comparative Example 2, the high-strength and high-toughness polycrystalline diamond composite sheet of Example 1 has superior mechanical properties, coefficient of thermal expansion, high temperature resistance and wear resistance.

[0152] Compared with Comparative Examples 3-5, the high-strength and high-toughness polycrystalline diamond composite sheet of Example 1 has a higher volume fraction of FCC phase. Moreover, under the condition that the ratio of high-entropy alloy to carbide remains consistent, the high-strength and high-toughness polycrystalline diamond composite sheet obtained in Example 1 has higher bending strength, greater hardness, lower abnormal grain growth, lower coefficient of thermal expansion, higher thermal failure temperature, and better wear resistance.

[0153] It is evident that the high-strength and high-toughness polycrystalline diamond composite sheet provided in this application has superior mechanical properties, heat resistance, and wear resistance compared to existing polycrystalline diamond composite sheets.

[0154] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A high-strength and high-toughness polycrystalline diamond compact, characterized by, Including diamond and high-entropy alloys; The high-entropy alloy contains a solid solution phase with a face-centered cubic crystal structure. The absolute value of the difference between the lattice constant a1 of the solid solution phase and the lattice constant a2 of the diamond is less than or equal to 5% of the lattice constant a2 of the diamond. The high-entropy alloy comprises Al, Co, Cr, Fe, and Ni; The atomic ratio of Al, Co, Cr, Fe and Ni is 1:1:1:1:(2.0-2.2).

2. The high-strength, high-toughness polycrystalline diamond composite sheet according to claim 1, characterized in that, The lattice constant a1 of the solid solution phase satisfies 3.391 Å ≤ a1 ≤ 3.749 Å; And / or, the solid solution phase accounts for a volume fraction of 50% or more of the high-entropy alloy.

3. The high-strength, high-toughness polycrystalline diamond composite sheet according to claim 2, characterized in that, The porosity of the high-strength, high-toughness polycrystalline diamond composite sheet is less than or equal to 0.5%. And / or, the abnormal grain growth of the diamond is less than or equal to 20%.

4. The high-strength, high-toughness polycrystalline diamond composite sheet according to claim 1, characterized in that, The high-strength and high-toughness polycrystalline diamond composite sheet also includes carbides; Preferably, the abnormal grain growth of the carbide is less than or equal to 20%.

5. A method for preparing a high-strength, high-toughness polycrystalline diamond composite sheet according to any one of claims 1-4, characterized in that, include: Diamond is laid on the surface of a matrix containing the high-entropy alloy, and then sintered to obtain the high-strength and high-toughness polycrystalline diamond composite sheet.

6. The method for preparing the high-strength, high-toughness polycrystalline diamond composite sheet according to claim 5, characterized in that, The high-entropy alloy has a mass fraction of 10%-18% in the matrix; And / or, the D50 particle size of the diamond is 1μm-30μm; And / or, the thickness of the diamond layer is 0.5mm-4mm.

7. The method for preparing the high-strength, high-toughness polycrystalline diamond composite sheet according to claim 6, characterized in that, The diamonds include two or more types of diamonds with a D50 size. Preferably, the diamond includes diamonds with three different diameters: d1, d2, and d3, where d1 satisfies 1μm≤d1≤5μm, d2 satisfies 5μm<d2≤10μm, and d3 satisfies 10μm<d3≤20μm.

8. The method for preparing the high-strength, high-toughness polycrystalline diamond composite sheet according to claim 5, characterized in that, The sintering includes: A matrix with diamond deposited on its surface is subjected to a first heat preservation treatment, a second heat preservation treatment, a pressure holding and cooling treatment, and a pressure release treatment at 6GPa-8.5GPa to obtain the high-strength and high-toughness polycrystalline diamond composite sheet; wherein the temperature of the first heat preservation treatment is lower than the temperature of the second heat preservation treatment.

9. The method for preparing the high-strength, high-toughness polycrystalline diamond composite sheet according to claim 8, characterized in that, The temperature of the first heat preservation treatment is 1420℃-1480℃, and the heat preservation time is 5min-10min; And / or, the temperature of the second heat preservation treatment is 1550℃-1620℃, and the heat preservation time is 20min-90min; And / or, the cooling rate of the pressure-holding and cooling process is 10℃ / min-20℃ / min; And / or, the pressure relief rate is 1 GPa / min - 2 GPa / min.

10. The method for preparing the high-strength, high-toughness polycrystalline diamond composite sheet according to claim 5, characterized in that, The matrix also includes carbides; Preferably, the carbide includes at least one of tungsten carbide, titanium carbide, and chromium carbide; Preferably, the method for preparing the matrix includes: hot isostatic pressing of raw materials containing the high-entropy alloy and the carbide at 1200℃-1600℃ and 50MPa-70MPa to obtain the matrix.

11. An alloy material, characterized in that, This includes the high-strength, high-toughness polycrystalline diamond composite sheet according to any one of claims 1-4, or the high-strength, high-toughness polycrystalline diamond composite sheet prepared by the preparation method according to any one of claims 5-10.

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