High toughness multi-component binder phase cemented carbide and method for producing the same

Abstract

This invention discloses a high-toughness multi-component binder phase cemented carbide and its preparation method. The cemented carbide is a composite material prepared by high-temperature carbide reduction as the hard phase and multi-component alloy prepared by gas atomization as the binder phase. By mass percentage, the binder phase accounts for 6-12% of the cemented carbide. By atomic percentage, the cemented carbide contains the following components: W 38-47%, C 38-47%, Co 3-7%, Fe 3-7%, and Ni 3-7%. The sum of the atomic percentages of these components accounts for more than 98% of the total atomic percentage of the cemented carbide, with the remainder being unavoidable impurities or modifying trace elements. This invention effectively avoids component segregation and the formation of brittle phases, achieving a breakthrough improvement in fracture toughness while maintaining basic service hardness. The cemented carbide of this invention can be applied in fields such as mining drilling and large-scale shield tunneling.

Description

Technical Field

[0001] This invention belongs to the field of cemented carbide material preparation technology, specifically relating to a high-toughness multi-component binder phase cemented carbide and its preparation method. Background Technology

[0002] Cemented carbide is a composite material consisting of a refractory metal carbide as the hard phase and a transition metal or alloy as the binder phase. Due to its excellent mechanical properties, it has been widely used in numerous industrial fields such as metal cutting, mining, and tool drilling. Cobalt (Co) and tungsten carbide (WC) have good wettability and are primarily used as binders in traditional cemented carbide, effectively reducing the sintering temperature of WC and imparting a certain degree of toughness to the alloy. However, Co is a scarce strategic metal, expensive, and its resources are dwindling. Furthermore, its toxicity and environmental impact cannot be ignored in powder production and use. Therefore, developing new, low-cost, environmentally friendly, and high-performance alternative binders has always been a research hotspot in the field of cemented carbide.

[0003] In recent years, incorporating multi-component alloys as novel binder phases into cemented carbides has become an important research direction. Based on their unique phase structure, multi-component binder phases can theoretically effectively control the comprehensive properties of cemented carbides, including hardness, toughness, wear resistance, and corrosion resistance. However, existing multi-component binder phase cemented carbides generally face a bottleneck of "severe inversion of strength and toughness" in actual preparation and service, especially their low fracture toughness, making it difficult to meet the stringent requirements for extremely high resistance to chipping under high-impact conditions such as mining drilling, large-scale tunnel boring machines, and heavy-duty cold heading dies.

[0004] The main reason for this problem is that existing conventional research paradigms, in pursuit of complex multi-component high-entropy effects, often tend to introduce complex alloying elements such as Cr, Cu, Al, and Ti into the binder phase. The introduction of these complex elements thermodynamically significantly narrows the carbon window of the alloy system, making it extremely difficult to control the carbon potential during sintering. For example, some elements with strong carboxyphilicity readily react at the interface to form brittle carbide phases, deteriorating mechanical properties; while the introduction of some elements (such as Cu) leads to intrinsic wettability polarization, resulting in microstructural defects such as coarse binder phase enrichment pools.

[0005] Furthermore, due to the extreme difficulty in achieving atomic-level solid solution through direct mixing of multi-element powders, existing technologies are generally forced to employ processes such as high-energy planetary ball milling for intensive mechanical alloying. This extremely high-energy ball milling mixing method is difficult to mass-produce and introduces irreversible work hardening and high-oxygen contamination into the powder. During subsequent liquid-phase sintering, excess oxygen easily triggers severe decarburization reactions, inevitably leading to the precipitation of brittle η-phase (such as the M6C-type decarburized phase) in the system. The presence of these brittle decarburized phases becomes the source of fatigue crack initiation and propagation, significantly reducing the material's fracture toughness and impact resistance, and making it highly susceptible to catastrophic chipping during heavy-load service.

[0006] Therefore, how to develop a multi-component binder cemented carbide with uniform phase structure, no brittle phase formation, and breakthrough impact toughness while ensuring the purity of components and mild processing is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0009] One objective of this invention is to provide a high-toughness multi-component binder phase cemented carbide to overcome the problems of carbon potential imbalance, easy precipitation of decarburized brittle phases, and severe inversion of strength and toughness in existing cemented carbides during preparation and service, thereby obtaining a new type of cemented carbide material with the advantages of extremely high fracture toughness, low cost, and environmental friendliness.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-toughness multi-component binder phase cemented carbide, wherein the cemented carbide is a composite material with tungsten carbide as the hard phase and a multi-component alloy as the binder phase; the content of the binder phase in the cemented carbide is 6~12% by mass percentage; the binder phase is prepared from spherical gas-atomized pre-alloyed powder, wherein the oxygen content of the spherical gas-atomized pre-alloyed powder is ≤1000 ppm and the median diameter D50 is 5~25 μm;

[0011] The cemented carbide contains the following components by atomic percentage: W 38-47%, C 38-47%, Co 3-7%, Fe 3-7%, and Ni 3-7%; the sum of the atomic percentages of the components accounts for more than 98% of the total atomic percentage of the cemented carbide, and the remainder are unavoidable impurities or modified trace elements.

[0012] As a preferred embodiment of the high-toughness multi-component binder phase cemented carbide of the present invention, wherein: the modified trace element is selected from one or more of V, Ta, and Nb, and the atomic percentage of a single modified trace element is less than 0.5%.

[0013] As a preferred embodiment of the high-toughness multi-component binder phase cemented carbide of the present invention, wherein: in the binder phase, the atomic percentages of Co, Fe and Ni are each 25-40%, and the atomic ratio between any two is 0.8-1.25:1.

[0014] As a preferred embodiment of the high-toughness multi-component binder phase cemented carbide of the present invention, the cemented carbide has the following properties:

[0015] (i) The binder phase in the cemented carbide matrix has a face-centered cubic single-phase solid solution structure, and no η-brittle phase precipitates in the microstructure of the cemented carbide.

[0016] (ii) The Vickers hardness HV30 of the cemented carbide is 900~1500, and the fracture toughness K IC The range is 13.0~25.0 MPa·m 1 / 2 ;

[0017] (iii) and / or, the cemented carbide showed no micro-expanding cracks at the indentation corners under a Vickers hardness test with a load of 30 kgf.

[0018] Another object of the present invention is to provide a method for preparing a high-toughness multi-component binder phase cemented carbide as described above, comprising,

[0019] Weigh the hard phase powder and the binder phase gas atomized pre-alloyed powder according to the specified ratio;

[0020] The forming agent, hard phase powder, and binder phase gas atomized pre-alloyed powder are sequentially ball-milled, dried and granulated, pressed and sintered in liquid phase.

[0021] As a preferred embodiment of the preparation method of the high-toughness multi-component binder phase cemented carbide of the present invention, wherein: the particle size of the binder phase gas atomized pre-alloy powder is ≤50μm, and the average particle size of the cemented phase powder is 0.5~10 μm.

[0022] In a preferred embodiment of the preparation method of the high-toughness multi-component binder phase cemented carbide of the present invention, the forming agent is a forming agent solution dissolved by ultrasound; the forming agent is added to a solvent and subjected to ultrasonic heating treatment to completely dissolve it.

[0023] The molding agent is selected from one or more of polyethylene glycol, paraffin wax, polyvinyl alcohol, stearic acid, zinc stearate, or rubber-based molding agents;

[0024] The solvent is a non-aqueous organic solvent, including one or more of anhydrous ethanol, acetone, n-hexane, heptane, or isopropanol;

[0025] The amount of the forming agent added is 1~3 wt.% based on the total mass of the hard phase powder and the binder phase gas atomized pre-alloyed powder, and the temperature of the ultrasonic heating treatment is 35~65 ℃.

[0026] As a preferred embodiment of the preparation method of the high-toughness multi-component binder phase cemented carbide of the present invention, the ball-to-material mass ratio of the ball mill is 3~10:1, the ball milling medium is cemented carbide balls, the ball milling speed is 40~120 rpm, and the total ball milling time is 1~18 h.

[0027] As a preferred embodiment of the preparation method of the high-toughness multi-component binder phase cemented carbide of the present invention, the ball mill is operated in an alternating forward and reverse rotation mode, and the specific operation cycle is: forward rotation for 15~50 min, pause for 0.5~5 min, reverse rotation for 15~50 min, pause for 0.5~5 min, and the cycle is repeated.

[0028] As a preferred embodiment of the preparation method of the high-toughness multi-component binder phase cemented carbide of the present invention, the drying granulation is carried out at a drying temperature of 60~120 ℃ and a drying time of 1~6 h, and granulation is performed by sieving after complete drying.

[0029] As a preferred embodiment of the preparation method of the high-toughness multi-component binder phase cemented carbide of the present invention, wherein: the pressing molding is cold pressing molding, and the molding pressure is 100~300 MPa;

[0030] The liquid phase sintering is gas pressure sintering. The sintering process is carried out under vacuum, hydrogen and argon protection conditions. The sintering temperature is 1350~1550 ℃, the sintering holding time is 30~120 min, and the sintering pressure is 1~10 MPa.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention employs a gentle horizontal ball milling process to mix a gas-atomized pre-alloyed powder of a specific composition with a hard phase powder. This overcomes the inherent defects of traditional high-energy ball milling of single-element powders, which easily introduces high-oxygen contamination and work hardening, regardless of the multi-component system. It completely blocks the high-oxygen contamination and work hardening introduced by traditional high-energy ball milling of single-element powders from the physical source, avoiding carbon potential imbalance and the formation of decarburized brittle phases (such as the η phase) during sintering, thus achieving extremely high microstructure purity. Thanks to this, this invention successfully overcomes the drawback of the severe inversion of strength and toughness in conventional multi-component cemented carbides. While maintaining the basic service hardness (HV30 of 900~1500), it achieves a breakthrough improvement in fracture toughness (fracture toughness K). IC The range is 13.0~25.0 MPa·m 1 / 2 It exhibits excellent damage tolerance (or no micro-propagating cracks at the indentation corners under high-load Vickers hardness testing); at the same time, the introduction of elements such as Fe and Ni significantly reduces the amount of expensive and toxic pure cobalt used, thus significantly reducing production costs. The process is simple, has high batch stability, and has great potential for large-scale industrial application. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0034] Figure 1 The XRD pattern of the cemented carbide sample in Example 1 of this invention;

[0035] Figure 2 This is a SEM image of the cemented carbide sample from Example 1 of the present invention.

[0036] Figure 3 The XRD pattern of the cemented carbide sample in Example 2 of this invention;

[0037] Figure 4 This is a SEM image of the cemented carbide sample from Example 2 of the present invention.

[0038] Figure 5 The XRD pattern of the cemented carbide sample in Example 3 of this invention;

[0039] Figure 6 This is a SEM image of the cemented carbide sample from Example 3 of the present invention.

[0040] Figure 7 The XRD pattern of the cemented carbide sample in Example 4 of this invention;

[0041] Figure 8 This is a SEM image of the cemented carbide sample from Example 4 of the present invention.

[0042] Figure 9 The SEM morphology and corresponding energy dispersive spectroscopy (EDS) distribution of the cemented carbide sample in Example 4 of this invention are shown below.

[0043] Figure 10 This is a microscopic image of the indentation morphology of the cemented carbide sample in Example 4 of the present invention after a 30 kgf load test;

[0044] Figure 11 The image shows the SEM morphology of the cemented carbide sample from Comparative Example 1.

[0045] Figure 12 The energy dispersive spectral density (EDS) distribution of the cemented carbide sample in Comparative Example 1 is shown in the surface scan diagram.

[0046] Figure 13 The image shows the SEM morphology of the cemented carbide sample from Comparative Example 2.

[0047] Figure 14 The energy dispersive spectral density (EDS) distribution of the cemented carbide sample in Comparative Example 2 is shown in the surface scan diagram.

[0048] Figure 15 The image shows the SEM morphology of the cemented carbide sample in Comparative Example 3.

[0049] Figure 16 The energy dispersive spectral density (EDS) distribution of the cemented carbide sample in Comparative Example 3 is shown in the surface scan diagram.

[0050] Figure 17 The image shows the SEM morphology of the cemented carbide sample from Comparative Example 4.

[0051] Figure 18 The energy dispersive spectral density (EDS) distribution of the cemented carbide sample in Comparative Example 4 is shown in the surface scan diagram.

[0052] Figure 19 The XRD pattern of the cemented carbide sample in Comparative Example 5 is shown.

[0053] Figure 20 The image shows the SEM morphology of the cemented carbide sample from Comparative Example 5.

[0054] Figure 21 The energy dispersive spectroscopy (EDS) distributions of the cemented carbide sample in Comparative Example 5 are shown in the surface and line scan diagrams.

[0055] Figure 22 The XRD pattern of the cemented carbide sample in Comparative Example 6 is shown.

[0056] Figure 23 The image shows the SEM morphology of the cemented carbide sample from Comparative Example 6.

[0057] Figure 24The energy dispersive spectroscopy (EDS) surface scan and line scan distributions of the cemented carbide sample in Comparative Example 6 are shown. Detailed Implementation

[0058] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0059] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0060] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0061] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0062] The CoFeNi gas-atomized pre-alloyed powder used in this example was purchased from Beijing Yanbang New Materials Technology Co., Ltd. Testing revealed the following core physicochemical properties of the gas-atomized pre-alloyed powder: approximately standard spherical powder particles with a concentrated particle size distribution (median diameter D50 of 11.8 μm and D90 of 19.7 μm); extremely low oxygen content (approximately 502 ppm O); a loose packing density of 3.29 g / cm³; and a total content of impurities such as carbon (C), sulfur (S), and phosphorus (P) below 0.006 wt%. Furthermore, the WC powder used was a conventional commercially available product.

[0063] Example 1

[0064] A high-toughness multi-component binder phase cemented carbide with a target composition of WC-6 wt.% CoFeNi is prepared as follows:

[0065] 94 g of WC powder with an average particle size of 2.9 μm, 6 g of CoFeNi gas-atomized pre-alloyed powder with an atomic ratio of 0-25 μm, and 0.06 g of carbon black were weighed. 2% of the total powder mass was weighed into bulk PEG, dissolved in an appropriate amount of anhydrous ethanol, and ultrasonically heated at 50 °C until completely dissolved. The powder and molding agent solution were transferred into a horizontal ball mill jar, and cemented carbide grinding balls were added at a ball-to-powder ratio of 5:1. The cemented carbide balls consisted of a mixture of 10 mm diameter large balls, 8 mm diameter medium balls, and 5 mm diameter small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar was 75 rpm, and the total ball milling time was 12 h. The ball milling process adopted an alternating forward and reverse rotation cycle, i.e., first rotating forward for 29 min, pausing for 1 min, then rotating in reverse for 29 min, pausing for 1 min, and repeating this cycle until the total time was completed. The mixed slurry was removed and dried in a constant temperature drying oven at 90 °C for 2 h. After the solvent evaporated, the material was granulated using a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, a dense, high-toughness multi-component binder phase cemented carbide sample was obtained.

[0066] The obtained samples were characterized by phase composition and microstructure, and their mechanical properties were tested. (See attached image.) Figure 1 The XRD pattern shown indicates that the alloy phase structure is pure, consisting only of a WC hard phase and an FCC-structured CoFeNi binder phase. No η-decarburized brittle phase or free carbon precipitation was observed. (See attached image) Figure 2 The SEM images show that the alloy has a dense and uniform microstructure, with the binder phase well distributed within the hard phase framework and no large or abnormal aggregates. The Vickers hardness (HV30) of this alloy is 1349.2 ± 18.7, and the fracture toughness is 13.67 ± 0.75 MPa·m. 1 / 2 .

[0067] Example 2

[0068] A high-toughness multi-component binder phase cemented carbide with a target composition of WC-8 wt.% CoFeNi is prepared as follows:

[0069] 92 g of WC powder with an average particle size of 2.9 μm, 8 g of CoFeNi gas-atomized pre-alloyed powder with an atomic ratio of 0-25 μm, and 0.06 g of carbon black were weighed. 2% of the total powder mass was weighed into bulk PEG, dissolved in an appropriate amount of anhydrous ethanol, and ultrasonically heated at 50 °C until completely dissolved. The powder and molding agent solution were transferred into a horizontal ball mill jar, and cemented carbide grinding balls were added at a ball-to-powder ratio of 5:1. The cemented carbide balls consisted of a mixture of 10 mm diameter large balls, 8 mm medium balls, and 5 mm small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar was 75 rpm, and the total ball milling time was 12 h. The ball milling process adopted an alternating forward and reverse rotation cycle, i.e., first rotating forward for 29 min, pausing for 1 min, then rotating in reverse for 29 min, pausing for 1 min, and repeating this cycle until the total time was completed. The mixed slurry was removed and dried in a constant temperature drying oven at 90 °C for 2 h. After the solvent evaporated, the material was granulated using a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, a dense, high-toughness multi-component binder phase cemented carbide sample was obtained.

[0070] The obtained samples were characterized by phase composition and microstructure, and their mechanical properties were tested. (See attached image.) Figure 3 The XRD pattern shown indicates that the alloy phase structure is pure, consisting only of a WC hard phase and an FCC-structured CoFeNi binder phase. No η-decarburized brittle phase or free carbon precipitation was observed. (See attached image) Figure 4 The SEM images show that the alloy has a dense and uniform microstructure, with the binder phase well distributed within the hard phase framework and no large or abnormal aggregates. The Vickers hardness (HV30) of this alloy is 1208.3 ± 4.2, and the fracture toughness is 14.64 ± 0.66 MPa·m. 1 / 2 .

[0071] Example 3

[0072] A high-toughness multi-component binder phase cemented carbide with a target ratio of WC-10 wt.% CoFeNi is prepared as follows:

[0073] Weigh 90 g of WC powder with an average particle size of 2.9 μm and 10 g of CoFeNi gas-atomized pre-alloyed powder with a particle size of 0-25 μm. Weigh 2% of the total powder mass of bulk PEG, dissolve it in an appropriate amount of anhydrous ethanol, and ultrasonically heat it at 50 °C until completely dissolved. Transfer the above powder and molding agent solution into a horizontal ball mill jar, add cemented carbide grinding balls at a ball-to-powder ratio of 5:1, wherein the cemented carbide balls are composed of a mixture of 10 mm diameter large balls, 8 mm medium balls, and 5 mm small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar is 75 rpm, and the total ball milling time is 12 h. The ball milling process adopts an alternating forward and reverse rotation cycle mode, that is, first rotate forward for 29 min, pause for 1 min, then rotate in reverse for 29 min, pause for 1 min, and repeat the cycle until the total time is completed. Take out the mixed slurry and dry it in a constant temperature drying oven at 90 °C for 2 h. After the solvent evaporated, the material was granulated using a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, a dense, high-toughness multi-component binder phase cemented carbide sample was obtained.

[0074] The obtained samples were characterized by phase composition and microstructure, and their mechanical properties were tested. (See attached image.) Figure 5 The XRD pattern shown indicates that the alloy phase structure is pure, consisting only of a WC hard phase and an FCC-structured CoFeNi binder phase. No η-decarburized brittle phase or free carbon precipitation was observed. (See attached image) Figure 6 The SEM images show that the alloy has a dense and uniform microstructure, with the binder phase well distributed within the hard phase framework and no large or abnormal aggregates. The Vickers hardness (HV30) of this alloy is 1052.5 ± 8.5, and the fracture toughness is 17.78 ± 1.27 MPa·m. 1 / 2 .

[0075] Example 4

[0076] A high-toughness multi-component binder phase cemented carbide with a target ratio of WC-12 wt.% CoFeNi is prepared as follows:

[0077] Weigh 88 g of WC powder with an average particle size of 2.9 μm and 12 g of CoFeNi gas-atomized pre-alloyed powder with a particle size of 0-25 μm. Weigh 2% of the total powder mass of bulk PEG, dissolve it in an appropriate amount of anhydrous ethanol, and ultrasonically heat it at 50 °C until completely dissolved. Transfer the above powder and molding agent solution into a horizontal ball mill jar, add cemented carbide grinding balls at a ball-to-powder ratio of 5:1, wherein the cemented carbide balls are composed of a mixture of 10 mm diameter large balls, 8 mm medium balls, and 5 mm small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar is 75 rpm, and the total ball milling time is 12 h. The ball milling process adopts an alternating forward and reverse rotation cycle mode, that is, first rotate forward for 29 min, pause for 1 min, then rotate in reverse for 29 min, pause for 1 min, and repeat the cycle until the total time is completed. Take out the mixed slurry and dry it in a constant temperature drying oven at 90 °C for 2 h. After the solvent evaporated, the material was granulated using a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, a dense, high-toughness multi-component binder phase cemented carbide sample was obtained.

[0078] The obtained samples were characterized by phase composition and microstructure, and their mechanical properties were tested. (See attached image.) Figure 7 The XRD pattern shown indicates that the alloy phase structure is pure, consisting only of a WC hard phase and an FCC-structured CoFeNi binder phase. No η-decarburized brittle phase or free carbon precipitation was observed. (See attached image) Figure 8 As shown in the SEM images, the alloy has a dense and uniform microstructure, with an extremely continuous and well-distributed binder phase. (See attached image.) Figure 9 The SEM morphology image and corresponding energy dispersive spectroscopy (EDS) distribution diagram show that the elements are uniformly distributed within the alloy. Testing revealed that the Vickers hardness (HV30) of this alloy remained at a baseline service level of 905.5 ± 24.4. Notably, due to the synergistic effect of the specific composition and mild process of this invention, an extremely pure and tough binder phase network was formed. During a 30 kgf (HV30) high-load Vickers hardness indentation impact test, no micro-propagating cracks were observed at the four corners of the indentation, as shown in the attached diagram. Figure 10 As shown in the figure. This phenomenon indicates that the alloy in this embodiment has extremely excellent resistance to microcrack initiation and propagation. Its actual fracture toughness has exceeded the upper limit of the conventional indentation method. Combined with theoretical calculations and confirmation from crack-free morphology, its fracture toughness value can reach 20.0 MPa·m. 1 / 2 The above, up to a maximum of 25.0 MPa·m 1 / 2 .

[0079] Comparative Example 1

[0080] Weigh 90 g of WC powder with an average particle size of 2.9 μm and 10 g of CoFeNiCr gas-atomized pre-alloyed powder with a particle size of 0-25 μm. Weigh PEG bulk at 2% of the total powder mass, dissolve it in an appropriate amount of anhydrous ethanol, and ultrasonically heat it at 50 ℃ until completely dissolved. Transfer the above powder and molding agent solution into a horizontal ball mill jar, add cemented carbide grinding balls at a ball-to-powder ratio of 5:1, wherein the cemented carbide balls are composed of a mixture of 10 mm diameter large balls, 8 mm medium balls, and 5 mm small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar is 75 rpm, and the total ball milling time is 12 h. The ball milling process adopts an alternating forward and reverse rotation cycle mode, that is, first rotate forward for 29 min, pause for 1 min, then rotate in reverse for 29 min, pause for 1 min, and repeat the cycle until the total time is completed. Take out the mixed slurry and dry it in a constant temperature drying oven at 90 ℃ for 2 h. After the solvent evaporated, the material was granulated using a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450℃ for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, the cemented carbide sample of Comparative Example 1 was obtained.

[0081] The obtained samples were characterized by microstructure and tested for mechanical properties. (See attached image.) Figure 11 The SEM images show that the alloy microstructure exhibits distinct contrasts of bright white, dark black, and gray, with the gray phase representing the precipitated carbon-deficient brittle phase (η phase). (See attached image.) Figure 12 As shown in the energy dispersive spectroscopy (EDS) pattern, the elemental distribution within the alloy is uneven, especially with Cr exhibiting a significant isolated and anomalous enrichment and segregation. The Vickers hardness (HV30) of this comparative alloy was measured to be 1249.8 ± 14.9, and its fracture toughness was only 10.28 ± 1.10 MPa·m. 1 / 2 .

[0082] Comparative Example 2

[0083] Weigh out 89.64 g of WC powder with an average particle size of 2.9 μm, 10 g of CoFeNiCr gas-atomized pre-alloyed powder with a particle size of 0-25 μm, and 0.36 g of carbon black. Weigh out PEG bulk at 2% of the total powder mass, dissolve it in an appropriate amount of anhydrous ethanol, and ultrasonically heat it at 50 ℃ until completely dissolved. Transfer the above powder and forming agent solution into a horizontal ball mill jar, add cemented carbide grinding balls at a ball-to-powder ratio of 5:1, wherein the cemented carbide balls are composed of a mixture of 10 mm diameter large balls, 8 mm medium balls, and 5 mm small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar is 75 rpm, and the total ball milling time is 12 h. The ball milling process adopts an alternating forward and reverse rotation cycle mode, that is, first rotate forward for 29 min, pause for 1 min, then rotate in reverse for 29 min, pause for 1 min, and repeat the cycle until the total time is completed. The mixed slurry was removed and dried in a constant temperature drying oven at 90 °C for 2 h. After the solvent evaporated, it was granulated by sieving through a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, the cemented carbide sample of Comparative Example 2 was obtained.

[0084] The obtained samples were characterized by microstructure and tested for mechanical properties. (See attached image.) Figure 13 As shown in the SEM morphology images, although the addition of carbon black suppressed the excessive precipitation of the gray, carbon-deficient, brittle η phase, large, anomalous aggregates appeared in the alloy microstructure. (Combined with attached...) Figure 14 The energy dispersive spectroscopy (EDS) distribution map shows that the anomalous aggregation region is a severely enriched binder phase pool (i.e., a "cobalt pool" defect). The comparative alloy was tested and found to have a Vickers hardness (HV30) of 1294.1 ± 11.7 and a fracture toughness of 10.72 ± 0.19 MPa·m. 1 / 2 .

[0085] Comparative Example 3

[0086] Weigh 90 g of WC powder with an average particle size of 2.9 μm and 10 g of CoFeNiCu gas-atomized pre-alloyed powder with a particle size of 0-25 μm. Weigh 2% of the total powder mass of bulk PEG, dissolve it in an appropriate amount of anhydrous ethanol, and ultrasonically heat it at 50 ℃ until completely dissolved. Transfer the above powder and molding agent solution into a horizontal ball mill jar, add cemented carbide grinding balls at a ball-to-powder ratio of 5:1, wherein the cemented carbide balls are composed of a mixture of 10 mm diameter large balls, 8 mm medium balls, and 5 mm small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar is 75 rpm, and the total ball milling time is 12 h. The ball milling process adopts an alternating forward and reverse rotation cycle mode, that is, first rotate forward for 29 min, pause for 1 min, then rotate in reverse for 29 min, pause for 1 min, and repeat the cycle until the total time is completed. Take out the mixed slurry and dry it in a constant temperature drying oven at 90 ℃ for 2 h. After the solvent evaporated, the material was granulated using a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450℃ for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, the cemented carbide sample of Comparative Example 3 was obtained.

[0087] The obtained samples were characterized by microstructure and tested for mechanical properties. (See attached image.) Figure 15 SEM topography images and attached Figure 16 As shown in the energy dispersive spectroscopy (EDS) pattern, the alloy microstructure exhibits obvious coarse, abnormally enriched regions of the binder phase (i.e., "cobalt pool" defects), indicating that the binder phase fails to uniformly and continuously coat the hard phase particles. The comparative alloy was tested and found to have a Vickers hardness (HV30) of 1136.9 ± 2.3 and a fracture toughness of 14.24 ± 0.62 MPa·m. 1 / 2 Example 3, with a lower binder phase content.

[0088] Comparative Example 4

[0089] Weigh 90 g of WC powder with an average particle size of 2.9 μm and 10 g of CoFeNiCuCr gas-atomized pre-alloyed powder with a particle size of 0-25 μm. Weigh PEG bulk at 2% of the total powder mass, dissolve it in an appropriate amount of anhydrous ethanol, and ultrasonically heat it at 50 ℃ until completely dissolved. Transfer the above powder and molding agent solution into a horizontal ball mill jar, add cemented carbide grinding balls at a ball-to-powder ratio of 5:1, wherein the cemented carbide balls are composed of a mixture of 10 mm diameter large balls, 8 mm medium balls, and 5 mm small balls in a mass ratio of 1:3:6. The actual rotation speed of the ball mill jar is 75 rpm, and the total ball milling time is 12 h. The ball milling process adopts an alternating forward and reverse rotation cycle mode, that is, first rotate forward for 29 min, pause for 1 min, then rotate in reverse for 29 min, pause for 1 min, and repeat the cycle until the total time is completed. Take out the mixed slurry and dry it in a constant temperature drying oven at 90 ℃ for 2 h. After the solvent evaporated, the material was granulated using a 60-mesh standard sieve. The resulting granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, the cemented carbide sample of Comparative Example 4 was obtained.

[0090] The obtained samples were characterized by microstructure and tested for mechanical properties. (See attached image.) Figure 17 SEM topography images and attached Figure 18 As shown in the energy dispersive spectroscopy (EDS) distribution, two severe typical defects simultaneously appeared in the alloy's microstructure: on the one hand, a large number of abnormally precipitated gray carbon-deficient brittle phases (η phase) were present in the matrix; on the other hand, extremely large binder phase enrichment pools (i.e., "cobalt pool" defects) were formed, and the elements within the enrichment pools exhibited severe phase separation and local segregation. Testing revealed that the Vickers hardness (HV30) of this comparative alloy was 1321.0±54.6, and the fracture toughness plummeted to only 9.50±0.49 MPa·m. 1 / 2 .

[0091] Comparative Example 5

[0092] Equivalent atomic ratios of elemental Co, Fe, Ni, and Cr powders were placed in a stainless steel ball mill jar containing cemented carbide grinding balls (ball-to-powder ratio of 10:1), and anhydrous ethanol was added as a process control agent. The mixture was ball-milled at 250 rpm for 40 h in a planetary ball mill (the milling process consisted of alternating cycles of 25 min forward rotation, 5 min pause, 25 min reverse rotation, and 5 min pause). Subsequently, the mixture was vacuum-dried at 80 °C for 6 h and passed through a 60-mesh standard sieve to obtain mechanically alloyed CoFeNiCr binder phase powder. Next, 90 g of WC powder with an average particle size of 1.0 μm and 10 g of the aforementioned CoFeNiCr powder were weighed. PEG was weighed at 2% of the total powder mass and transferred to a ball mill jar along with the powder. Carbide grinding balls (5:1 ball-to-powder ratio, composed of 10 mm, 8 mm, and 5 mm balls in a 1:3:6 mass ratio) and an appropriate amount of ethanol were added. The mixture was wet-milled at 250 rpm for 6 h on a planetary ball mill. The homogenized powder slurry was vacuum-dried at 80 °C for 6 h and then sieved. The granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, the carbide sample of Comparative Example 5 was obtained.

[0093] The obtained samples were characterized by phase composition, microstructure, and mechanical properties. (See attached image.) Figure 19 The XRD pattern shows that, compared to the pure alloy of the examples, this comparative alloy exhibits a large number of η-brittle phase impurity peaks with extremely high diffraction intensity. Further combined with the attached... Figure 20 The SEM images show that the alloy matrix is ​​filled with large, elongated, needle-like brittle phases, which severely disrupt the continuity of the microstructure. (See attached image.) Figure 21 As shown in the surface and line scan energy dispersive spectroscopy (EDS) distributions, significant Cr segregation is observed within the alloy. This is not only due to the introduction of complex elements such as Cr, but also because of the use of conventional multi-element powder mixing and high-energy planetary ball milling processes. This process inevitably introduces severe surface oxygen contamination and work hardening into elemental powders with high specific surface areas (such as Fe and Ni), leading to a violent decarburization reaction during subsequent liquid-phase sintering. Testing revealed that the Vickers hardness (HV30) of this comparative alloy was 1900.4 ± 28.2, and the fracture toughness decreased to 7.59 ± 0.11 MPa·m. 1 / 2 .

[0094] Comparative Example 6

[0095] Weigh out powders of elemental Co, Cr, Fe, Ni, Al, and Ti (with an atomic ratio satisfying (CoFeNiCr)). 96 Al2Ti2 was placed in a stainless steel ball mill jar containing cemented carbide grinding balls (ball-to-material ratio of 10:1), and anhydrous ethanol was added as a process control agent. The mixture was ball-milled at 250 rpm for 40 h in a planetary ball mill (the milling process consisted of alternating cycles of 25 min forward rotation, 5 min pause, 25 min reverse rotation, and 5 min pause). It was then vacuum-dried at 80 °C for 6 h and passed through a 60-mesh standard sieve to obtain a mechanically alloyed multi-component binder phase powder. Next, 90 g of WC powder with an average particle size of 1.0 μm and 10 g of the binder phase powder obtained above were weighed. PEG was weighed at 2% of the total powder mass and transferred to the ball mill jar along with the powder. Cemented carbide grinding balls (ball-to-material ratio of 5:1, a mixture of 10 mm, 8 mm, and 5 mm grinding balls in a 1:3:6 mass ratio) and an appropriate amount of anhydrous ethanol were added, and the mixture was wet-milled at 250 rpm for 6 h in a planetary ball mill. The mixed powder slurry was vacuum dried at 80 °C for 6 h and then sieved. The granules were then cold-pressed into compacts under a pressure of 100 MPa. Finally, the compacts were placed in a gas pressure sintering furnace for liquid-phase sintering at 1450 °C for 60 min, with an argon pressure of 6 MPa applied during the holding period. After furnace cooling, the cemented carbide sample of Comparative Example 6 was obtained. The phase composition, microstructure, and mechanical properties of the obtained sample were characterized and tested. (See attached...) Figure 22 The XRD pattern shows that a large amount of η-decarburized brittle phase has precipitated inside the alloy. Combined with the attached... Figure 23 The SEM images show that the microstructure is filled with large, long, needle-like brittle phases, and also contains large pores and defects. (See attached image.) Figure 24 As shown in the surface and line scan energy dispersive spectroscopy (EDS) distributions, the strongly oxygen-loving elements Al and Ti exhibited extremely severe local segregation in the defect region, accompanied by a very high concentration of oxygen enrichment, forming unusually complex oxide inclusions. This further confirms that the conventional process of high-energy planetary ball milling using elemental powders is highly susceptible to severe oxygen absorption, leading to catastrophic decarburization embrittlement and inclusion defects in multi-component systems. The comparative alloy was tested to have a Vickers hardness (HV30) of 1988.8 ± 26.5, while its fracture toughness decreased to 7.2 ± 0.16 MPa·m. 1 / 2 .

[0096] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-toughness multi-component binder phase cemented carbide, characterized in that: The cemented carbide is a composite material with tungsten carbide as the hard phase and a multi-component alloy as the binder phase; the binder phase has a content of 6-12% by mass percentage in the cemented carbide; the binder phase is prepared from spherical gas-atomized pre-alloyed powder, and the oxygen content of the spherical gas-atomized pre-alloyed powder is ≤1000 ppm and the median diameter D50 is 5-25 μm; The cemented carbide contains the following components by atomic percentage: W 38-47%, C 38-47%, Co 3-7%, Fe 3-7%, and Ni 3-7%; the sum of the atomic percentages of the components accounts for more than 98% of the total atomic percentage of the cemented carbide, and the remainder are unavoidable impurities or modified trace elements.

2. The high-toughness multi-component binder phase cemented carbide as described in claim 1, characterized in that: The modified trace element is selected from one or more of V, Ta, and Nb, and the atomic percentage of a single modified trace element is less than 0.5%.

3. The high-toughness multi-component binder phase cemented carbide as described in claim 1 or 2, characterized in that: In the binder phase, the atomic percentages of Co, Fe, and Ni are each 25% to 40%, and the atomic ratio between any two is 0.8 to 1.25:

1.

4. The high-toughness multi-component binder phase cemented carbide as described in claim 3, characterized in that: The cemented carbide has the following properties: (i) The binder phase in the cemented carbide matrix has a face-centered cubic single-phase solid solution structure, and no η-brittle phase precipitates in the microstructure of the cemented carbide. (ii) The Vickers hardness HV30 of the cemented carbide is 900~1500, and the fracture toughness K IC The range is 13.0~25.0 MPa·m 1 / 2 ; (iii) and / or, the cemented carbide showed no micro-expanding cracks at the indentation corners under a Vickers hardness test with a load of 30 kgf.

5. The method for preparing high-toughness multi-component binder phase cemented carbide as described in any one of claims 1 to 4, characterized in that: include, Weigh the hard phase powder and the binder phase gas atomized pre-alloyed powder according to the specified ratio; The forming agent, hard phase powder, and binder phase gas atomized pre-alloyed powder are sequentially ball-milled, dried and granulated, pressed and sintered in liquid phase.

6. The method for preparing high-toughness multi-component binder phase cemented carbide as described in claim 5, characterized in that: The particle size of the binder phase gas atomized pre-alloyed powder is ≤50μm, and the average particle size of the hard phase powder is 0.5~10 μm.

7. The method for preparing high-toughness multi-component binder phase cemented carbide as described in claim 5, characterized in that: The molding agent is a molding agent solution dissolved by ultrasound; the molding agent is added to a solvent and then subjected to ultrasonic heating to completely dissolve it. The molding agent is selected from one or more of polyethylene glycol, paraffin wax, polyvinyl alcohol, stearic acid, zinc stearate, or rubber-based molding agents; The solvent is a non-aqueous organic solvent, including one or more of anhydrous ethanol, acetone, n-hexane, heptane, or isopropanol; The amount of the forming agent added is 1~3 wt.% based on the total mass of the hard phase powder and the binder phase gas atomized pre-alloyed powder, and the temperature of the ultrasonic heating treatment is 35~65 ℃.

8. The method for preparing high-toughness multi-component binder phase cemented carbide as described in any one of claims 5 to 7, characterized in that: The ball-to-material mass ratio of the ball mill is 3~10:1, the ball milling media are cemented carbide balls, the ball milling speed is 40~120 rpm, and the total ball milling time is 1~18 h.

9. The method for preparing high-toughness multi-component binder phase cemented carbide as described in claim 8, characterized in that: The ball mill operates in an alternating forward and reverse rotation mode. The specific operating cycle is as follows: forward rotation for 15~50 minutes, pause for 0.5~5 minutes, reverse rotation for 15~50 minutes, pause for 0.5~5 minutes, and the cycle is repeated.

10. The method for preparing high-toughness multi-component binder phase cemented carbide as described in any one of claims 5 to 7 and 9, characterized in that: The drying and granulation process involves a drying temperature of 60-120 ℃ and a drying time of 1-6 h. After complete drying, the granules are sieved. The pressing and molding process is cold pressing, with a molding pressure of 100~300 MPa; The liquid phase sintering is gas pressure sintering. The sintering process is carried out under vacuum, hydrogen and argon protection conditions. The sintering temperature is 1350~1550 ℃, the sintering holding time is 30~120 min, and the sintering pressure is 1~10 MPa.

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