Cemented carbide and method for producing the same

Abstract

The application discloses a cemented carbide and a preparation method thereof. The cemented carbide comprises a WC phase, a Co bonding phase, a first cubic solid solution SS1 and a second cubic solid solution SS2, the SS1 comprises 30%< W < 50%, 10% < Ti <= 30%, 0 <= Ta <= 30%, 0 <= Nb <= 30%, 0 <= N < 2%, and the balance is C, the SS2 comprises 10% < W <= 30%, 30% < Ti < 70%, 0 <= Ta <= 10%, 0 <= Nb <= 10%, N >= 2%, and the balance is C. The preparation method comprises preparing raw materials, compression molding and alloy sintering. The cemented carbide can significantly improve the room temperature and high temperature hardness of the alloy, and is suitable for high-speed and high-efficiency machining of numerical control cutters.

Description

Technical Field

[0001] This invention belongs to the field of cemented carbide cutting tool technology, and relates to a cemented carbide and its preparation method, specifically to a cemented carbide containing a bicubic solid solution phase and its preparation method. Background Technology

[0002] The addition of cubic refractory metal carbide or carbonitride solid solutions to WC-Co cemented carbide, denoted as (W / Ti / Ta / Nb)(C / N), significantly improves the hardness of the alloy, especially enhancing its resistance to plastic deformation during high-temperature, high-speed machining. However, the cubic solid solution (W / Ti / Ta / Nb)(C / N) is a brittle hard phase; an excessively high proportion will cause solid solution aggregation and coarsening, thereby significantly reducing the alloy's bending strength. Therefore, controlling the solid solution proportion within an appropriate range while regulating the distribution of the cubic solid solution (W / Ti / Ta / Nb)(C / N) to improve the alloy's mechanical properties and tool life has always been a research hotspot in the field of cemented carbide.

[0003] Chinese patent document CN106048360 discloses a dual-gradient cemented carbide with added ZrC / HfC composition. Its core lies in utilizing the interstitial dissolution between (W,Ti,Ta,Nb)C solid solutions and (W,Ti,Ta,Nb,Zr / Hf)C solid solutions to form a dual-gradient structure cemented carbide. The core of this alloy exhibits both Ti-rich and Zr / Hf-rich solid solutions. However, the addition of the indispensable ZrC / HfC component in this experimental scheme is problematic. ZrC readily forms ZrO2 defects in powder metallurgy, which are distributed throughout the gradient alloy, significantly reducing its bending strength. Furthermore, the term "Ti-rich solid solution" in this document is relative to "ZrC / HfC-rich solid solution," and its essence is a conventional (W / Ti / Ta / Nb)(C / N) solid solution.

[0004] In a journal article (Relation between the nitrogen gas pressure and structure characterization of WC-TiCN-Co graded cemented carbides. Journal of Alloys and Compounds, 2020), Li Na et al. prepared a hard alloy with a surface rich in cubic solid solution layers by sintering in a N2 atmosphere. The alloy has cubic solid solution phases in both the outermost layer and the core. However, both are conventional cubic solid solutions (W / Ti / Ta / Nb)(C / N) with the same composition and structure, and do not belong to two different cubic solid solutions. Furthermore, the enrichment of the brittle solid solution phase on the surface will significantly reduce the bending strength of the alloy. The microstructure of the core is unchanged compared to conventional alloys, and it cannot significantly improve the room temperature and high temperature hardness of the alloy. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a cemented carbide and its preparation method that can improve the high-temperature hardness of the matrix and meet the requirements of complex high-temperature rapid machining conditions without changing the composition and particle size system of the cemented carbide matrix.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0007] A cemented carbide comprising a WC phase, a Co binder phase, a first cubic solid solution SS1, and a second cubic solid solution SS2; the first cubic solid solution SS1 contains elements with the following mass fractions: 30% < W < 50%, 10% < Ti ≤ 30%, 0 ≤ Ta ≤ 30%, 0 ≤ Nb ≤ 30%, 0 ≤ N < 2%, with the balance being C; the second cubic solid solution SS2 contains elements with the following mass fractions: 10% < W ≤ 30%, 30% < Ti < 70%, 0 ≤ Ta ≤ 10%, 0 ≤ Nb ≤ 10%, N ≥ 2%, with the balance being C. The mass fractions of each element in the first cubic solid solution SS1 are based on the mass of the first cubic solid solution SS1, and the mass fractions of each element in the second cubic solid solution SS2 are based on the mass of the second cubic solid solution SS2.

[0008] Preferably, in the aforementioned cemented carbide, the first cubic solid solution SS1 contains the following elements by mass fraction: 33% < W < 45%, 15% < Ti < 25%, 3% ≤ Ta < 25%, 3 ≤ Nb < 25%, 0 ≤ N < 2%, with the balance being C; the second cubic solid solution contains the following elements by mass fraction: 15% < W < 25%, 40% < Ti < 60%, 2% < Ta < 10%, 2% < Nb < 10%, N > 2%, with the balance being C.

[0009] Preferably, in the aforementioned cemented carbide, the mass fraction of each phase is: 5% ≤ Co binder phase ≤ 15%, 0 < first cubic solid solution SS1 and second cubic solid solution SS2 ≤ 25%, and the remainder is WC phase.

[0010] More preferably, in the aforementioned cemented carbide, the mass fraction of each phase is: 5% ≤ Co binder phase ≤ 10%, 5% < first cubic solid solution SS1 and second cubic solid solution SS2 ≤ 20%, and the remainder is WC phase.

[0011] Preferably, in the aforementioned cemented carbide, the average value of the equivalent circle diameter of the first cubic solid solution SS1 particles is D. ss1 Let the average equivalent circle diameter of the particles in the second cubic solid solution SS2 be D. ss2 Then 0.5μm < D ss1 <1.5μm, 0.5μm<D ss2 <1.5μm.

[0012] The aforementioned cemented carbide, preferably, D ss2 <D ss1 .

[0013] Preferably, in the aforementioned cemented carbide, the first cubic solid solution SS1 and the second cubic solid solution SS2 are discretely distributed in the cemented carbide, the particle size of the first cubic solid solution SS1 is <15μm, and the particle size of the second cubic solid solution SS2 is <15μm.

[0014] More preferably, in the aforementioned cemented carbide, the particle size of the first cubic solid solution SS1 is <10μm, and the particle size of the second cubic solid solution SS2 is <10μm.

[0015] In the aforementioned cemented carbide, it is further preferred that the particle size of the first cubic solid solution SS1 is <7μm and the particle size of the second cubic solid solution SS2 is <7μm.

[0016] As a general technical concept, the present invention also provides a method for preparing the above-mentioned cemented carbide, comprising the following steps:

[0017] (1) Prepare raw materials: Prepare raw materials according to the elements and proportions of cemented carbide;

[0018] (2) Pressing and molding: The above raw materials, molding agent, ball milling rod and alcohol are added to a ball mill for wet grinding. The resulting slurry is dried and sieved to obtain a mixture, which is then pressed into a green embryo.

[0019] (3) Alloy sintering: The above green blank is heated to 300℃~450℃ for H2 dewaxing and removal of molding agent PEG. Then, under vacuum conditions, it is heated to 1300℃~1370℃, filled with 20mbar~200mbar inert gas Ar and sintered for 20min~60min. Then, it is heated to 1420℃~1480℃ and held for 30min~120min. Then, it is cooled to 1000℃~1200℃ and cooled to room temperature under H2 conditions to obtain cemented carbide.

[0020] In the above-mentioned method for preparing cemented carbide, preferably, in step (1), the raw material sources for W element include WC powder and / or (W,Ti)C solid solution powder; the raw material sources for Ti element include one or more of TiC powder, TiCN powder, (W,Ti)C solid solution powder, and TiN powder; the raw material sources for Ta element include TaC powder and / or (Ta,Nb)C solid solution powder; the raw material sources for Nb element include NbC powder and / or (Ta,Nb)C solid solution powder; the source of N element includes TiCN powder and / or TiN powder; and the raw material source for Co element is Co powder. The C element originates from the carbides or carbonitrides of the aforementioned raw materials.

[0021] In the preferred embodiment of the above-mentioned method for preparing cemented carbide, in step (1), the raw materials prepared include Co powder, (W,Ti)C solid solution powder, TiCN powder, (Ta,Nb)C solid solution powder and WC powder. Based on the total mass of the raw materials, the percentages by mass are as follows: Co powder is 5% to 15%, (W,Ti)C solid solution powder is 2% to 10%, TiCN powder is 2% to 10%, (Ta,Nb)C solid solution powder is 0% to 10%, and the remainder is WC powder.

[0022] In the above-mentioned method for preparing cemented carbide, preferably, in step (1), the FSSS particle size of the Co powder is 1.2 μm to 1.5 μm, the FSSS particle size of the (W,Ti)C solid solution powder is 1.5 μm to 2.0 μm, the FSSS particle size of the TiCN powder is 0.8 μm to 1.2 μm, the FSSS particle size of the (Ta,Nb)C solid solution powder is 1.0 μm to 1.5 μm, and the FSSS particle size of the WC powder is 3.0 μm to 4.0 μm.

[0023] In the above-mentioned method for preparing cemented carbide, preferably, in step (2), the forming agent is PEG, the mass of the forming agent is 1.5% to 2.5% of the total mass of the raw materials in step (1), the mass of the ball milling rod is 4 to 6 times the total mass of the raw materials in step (1), the amount of alcohol added is 200 mL to 300 mL of alcohol per kilogram of raw materials, and the wet milling time is 25 h to 40 h.

[0024] In the above-mentioned method for preparing cemented carbide, preferably, in step (2), the drying temperature is 60℃~120℃, the drying time is 2h~3h, and the sieving is 60 mesh~80 mesh.

[0025] In the above-mentioned method for preparing cemented carbide, preferably, in step (3), the removal of the forming agent is carried out using the TORVAC process.

[0026] The production of cemented carbide can be achieved by adjusting the raw materials and their proportions according to the predetermined requirements of the amount of elements. This means that the raw materials and their proportions can be adjusted according to the limited standards of a certain series of elements, and the adjustment of the raw materials and their proportions can meet the element limits.

[0027] This invention takes a novel approach by adding a cubic solid solution phase to a three-phase alloy of WC, Co, and a solid solution (W / Ti / Ta / Nb)(C / N). This newly added cubic solid solution has higher hardness than the original solid solution and is dispersed throughout the alloy, significantly improving its high-temperature hardness. Typically, adding one or more of TiC, TaC, NbC, TiCN, (W,Ti)C, and (Ta,Nb)C to a cemented carbide WC-Co will cause these cubic carbides to form a solid solution (W / Ti / Ta / Nb)(C / N), which is the first cubic solid solution SS1 of this invention. Depending on the sintering process, there may be microscopic elemental inhomogeneity between the solid solution phase particles, but they are all of the same phase. Under this solid solution growth mechanism, forming another cubic solid solution with significantly different composition and mechanical properties in the cemented carbide presents technical difficulties. Through extensive exploration of element design (adjustable raw material ratio) and sintering process, this invention enables the co-synthesis of bicubic phases SS1 and SS2 under current element design and sintering process conditions. This results in higher room temperature and high temperature hardness of cemented carbide, significantly improving the high temperature resistance to plastic deformation of cemented carbide cutting tools.

[0028] As shown in Table 1, the hardness of TiC and TiN is much higher than that of WC. The solid solution in the core of conventional cemented carbide is a high-W-content (W,Ti,Ta,Nb) C / N solid solution formed based on TiC, TiN, or TiCN, which is the first cubic solid solution in this invention, denoted as SS1. The core objective of this invention is to synthesize, in addition to SS1, a second cubic solid solution with TiC, TiN, or TiCN as the base and Ti content predominant, denoted as SS2. SS2 and SS1 are co-distributed in the alloy. The significant increase in Ti content results in SS2 having higher room temperature and high temperature hardness than SS1, thereby improving the overall room temperature and high temperature hardness of the alloy.

[0029] Table 1. Mechanical property parameters of commonly used refractory metal elements

[0030]

[0031] This invention realizes a cemented carbide comprising four phases: WC phase, Co binder phase, first cubic solid solution SS1, and second cubic solid solution SS2. SS1 and SS2 are cubic solid solutions formed by the solid solution of carbides or carbonitrides of refractory metals such as W, Ti, Ta, and Nb. The elemental proportions in SS1 and SS2 are significantly different, and they appear as two-phase materials under a metallographic microscope.

[0032] In this invention, the hardness of SS2 is higher than that of SS1, the volume fraction of SS2 in the cemented carbide is less than that of SS1, and SS1 and SS2 are discretely distributed in the cemented carbide, which can improve the room temperature and high temperature hardness of the alloy.

[0033] Compared with the prior art, the advantages of the present invention are as follows:

[0034] (1) In the cemented carbide of the present invention, two cubic solid solution phases with different proportions of synergistic elements, SS1 and SS2, are simultaneously distributed in the alloy. SS2 has a higher Ti content and a higher hardness than SS1, which makes the cemented carbide have higher room temperature and high temperature hardness. This can significantly improve the ability of the alloy tool to resist plastic deformation at high temperature. In addition, the cemented carbide of the present invention maintains the WC-Co-(W / Ti / Ta / Nb)(C / N) material system without adding new raw materials. Compared with the conventional solid solution SS1 with W content as the dominant component, the present invention has obvious advantages and is suitable for mass production.

[0035] (2) The preparation method of the present invention ensures that the alloy is dense and the solid solution components are fully diffused through element design (raw material design) and sintering process (such as sintering temperature and holding time). At the same time, the solid solution is uniformly dispersed in the alloy without solid solution aggregation or abnormal growth, thus ensuring the overall mechanical properties and high-temperature hardness of the alloy. Attached Figure Description

[0036] Figure 1 This is a microstructure image (SEM, 10000x) of the cemented carbide core of Embodiment 1 of the present invention.

[0037] Figure 2 This is a microstructure image (SEM, 8000x) of the cemented carbide core of Embodiment 2 of the present invention.

[0038] Figure 3 This is a microstructure image of the cemented carbide core in Comparative Example 1 (SEM, 5000x magnification). Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. The raw materials and instruments used in the following embodiments are all commercially available.

[0040] Example 1

[0041] A cemented carbide of the present invention includes a WC phase, a Co binder phase, a first cubic solid solution SS1 and a second cubic solid solution SS2, wherein the first cubic solid solution SS1 and the second cubic solid solution SS2 respectively contain the elements and mass fractions shown in Table 2.

[0042] Table 2. Elemental content (wt%) of SS1 and SS2 in Example 1

[0043]

[0044] In this embodiment, based on the mass of cemented carbide, the mass fraction of each phase in the cemented carbide is as follows: Co binder phase is 7.2%, the sum of the mass fractions of the first cubic solid solution SS1 and the second cubic solid solution SS2 is 16.7%, and the remainder is WC phase.

[0045] In this embodiment, D ss1 It is 0.82μm, D ss2 It is 0.68μm.

[0046] In this embodiment, the first cubic solid solution SS1 and the second cubic solid solution SS2 are discretely distributed in the cemented carbide without aggregation. The particle size of the first cubic solid solution SS1 is <3.7μm and the particle size of the second cubic solid solution SS2 is <0.85μm.

[0047] A method for preparing cemented carbide according to this embodiment includes the following steps:

[0048] (1) Prepare raw materials: Prepare raw materials according to the raw material composition and specifications in Table 3.

[0049] Table 3. Raw material composition of cemented carbide in Example 1

[0050] raw material Quality percentage (%) Particle size specification FSSS (μm) (W,Ti)C solid solution powder 4.3 1.5-2.0 (Ta,Nb)C solid solution powder 3.6 1.0-1.5 TiCN powder 2.7 0.8-1.2 Co powder 7.2 1.2-1.5 WC powder margin 3.0-4.0

[0051] (2) Pressing and molding: Add all the raw materials, grinding rods, and molding agent PEG from Table 3 above to a ball mill. The total weight of the raw materials is 1 kg, the grinding rods are 5 kg, and the molding agent PEG is 20 g. Add 275 mL of alcohol, wet grind for 32 h, and then vacuum dry the slurry at 100 °C for 3 h. Then, sieve it through an 80-mesh screen to obtain a uniform mixture. Press the mixture into green bodies of 7.9 mm × 6.4 mm × 21 mm and wait for sintering.

[0052] (3) Alloy sintering: The green sample was first dewaxed with H2 and TORVAC at 450℃ to remove PEG from the sample. Then, the temperature was raised to 1350℃ under vacuum, filled with 40mbar of Ar inert atmosphere and sintered for 30min. The temperature was raised to 1450℃ and held for 60min. Then, the temperature was lowered to 1200℃ and cooled to room temperature under H2 conditions. The sample was then removed to obtain cemented carbide.

[0053] Testing and Analysis: The cemented carbide prepared in this embodiment was cut to expose the core cross-section. The cross-section was then metallographically ground and polished using a Struer metallographic sample preparation instrument until it was flat, smooth, and free of obvious scratches. A Zeiss Supra 55 field emission scanning electron microscope and an Oxford X-MAX 50mm energy dispersive spectrometer were used for further analysis. 2 The microstructure and EDS composition of the alloy core were analyzed. High-temperature hardness testing was performed using a ZD-HVZHT-10 instrument from Zongde Electromechanical, under a vacuum atmosphere.

[0054] like Figure 1 As shown in the figure, the black dashed arrow points to the first cubic solid solution SS1 in the cemented carbide, and the white solid arrow points to the second cubic solid solution SS2. The cemented carbide of Example 1 achieves the structural feature of SS1 and SS2 being simultaneously distributed in the alloy. The center of the solid solution particle indicated by the arrow is the test location of energy dispersive spectroscopy (EDS). The EDS composition test results are shown in Table 2. To ensure the reliability of the results, EDS point mode was randomly sampled at any location in the alloy, with more than 10 sampling points, and all sampled data were averaged. The high-temperature hardness test results are shown in Table 6. To ensure the reliability of the data, three hardness tests were performed at each temperature and the average was calculated.

[0055] Example 2

[0056] A cemented carbide of the present invention includes a WC phase, a Co binder phase, a first cubic solid solution SS1 and a second cubic solid solution SS2, wherein the first cubic solid solution SS1 and the second cubic solid solution SS2 respectively contain the elements and mass fractions shown in Table 4.

[0057] Table 4. Elemental content (wt%) of SS1 and SS2 in Example 2

[0058]

[0059] In this embodiment, based on the mass of cemented carbide, the mass fraction of each phase in the cemented carbide is as follows: Co binder phase is 7.2%, the sum of the mass fractions of the first cubic solid solution SS1 and the second cubic solid solution SS2 is 19.2%, and the remainder is WC phase.

[0060] In this embodiment, D ss1It is 1.05μm, D ss2 It is 0.89μm.

[0061] In this embodiment, the first cubic solid solution SS1 and the second cubic solid solution SS2 are discretely distributed in the cemented carbide without aggregation. The particle size of the first cubic solid solution SS1 is <5.7μm and the particle size of the second cubic solid solution SS2 is <1.2μm.

[0062] A method for preparing a cemented carbide according to the present invention includes the following steps:

[0063] (1) Preparation of raw materials: Prepare raw materials according to the composition and specifications in Table 5. Compared with Example 1, Example 2 maintains the same ratio of Co and (Ta,Nb)C solid solution, but reduces the mass fraction of (W,Ti)C solid solution, increases the TiCN ratio, and adjusts the WC ratio accordingly.

[0064] Table 5. Raw material list of cemented carbide in Example 2

[0065] raw material Quality percentage (%) Particle size specification FSSS (μm) (W,Ti)C solid solution powder 3.6 1.5-2.0 (Ta,Nb)C solid solution powder 3.6 1.0-1.5 TiCN powder 4.4 0.8-1.2 Co powder 7.2 1.2-1.5 WC powder margin 3.0-4.0

[0066] (2) Pressing and molding: Add all the raw materials, molding agent PEG, and milling rods from Table 5 above to a ball mill. The total weight of the raw materials is 1 kg, the molding agent PEG is 20 g, the milling rod is 5 kg, and 275 mL of alcohol is added. After wet milling for 32 h, the slurry is vacuum dried at 100 °C for 3 h and then sieved through an 80-mesh sieve to obtain a uniform mixture. Press the mixture into green bodies of 7.9 mm × 6.4 mm × 21 mm and wait for sintering.

[0067] (3) Alloy sintering: The green sample was first dewaxed and trolleyed at 450℃ using H2 to remove PEG from the sample. Then, the temperature was raised to 1350℃ under vacuum, and an inert Ar atmosphere of 40mbar was introduced and sintered for 30min. The temperature was then raised to 1450℃ and held for 60min. The temperature was then lowered to 1200℃ and cooled to room temperature under H2 conditions. The sample was then removed to obtain cemented carbide.

[0068] The detection and analysis methods are the same as in Example 1.

[0069] like Figure 2As shown in the figure, the black "+" sign indicates the first cubic solid solution SS1 in the cemented carbide, and the white "+" sign indicates the second cubic solid solution SS2. The alloy in Example 2 achieved the structural characteristic of SS1 and SS2 simultaneously distributed within the alloy. The center of the solid solution particle indicated by the "+" sign is the test location for Energy Dispersive Spectroscopy (EDS). The EDS composition results are shown in Table 4. To ensure the reliability of the results, EDS point mode was used to randomly collect data at any location on the alloy, with more than 10 data points collected. All collected data were averaged. The high-temperature hardness test results are shown in Table 6. To ensure the reliability of the data, three hardness tests were performed at each temperature, and the average was calculated.

[0070] Comparative Example 1

[0071] To better demonstrate the bicubic solid solution structure and high-temperature hardness advantages of the cemented carbide in the embodiments, a product developed by the applicant (prior technology) was selected as the comparative example, and its core microstructure is as follows. Figure 3 As shown, it contains WC, Co and SS1 solid solutions, but no SS2 solid solution phase.

[0072] Table 6. Comparison of Vickers hardness between Examples 1 & 2 and Comparative Example 1

[0073]

[0074]

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A cemented carbide, characterized in that, The hard alloy comprises a WC phase, a Co binder phase, a first cubic solid solution SS1 and a second cubic solid solution SS2; the first cubic solid solution SS1 comprises the following mass fractions of elements: 30% < W < 50%, 10% < Ti ≤ 30%, 0 ≤ Ta ≤ 30%, 0 ≤ Nb ≤ 30%, 0 ≤ N < 2%, and the balance being C; the second cubic solid solution SS2 comprises the following mass fractions of elements: 10% < W ≤ 30%, 30% < Ti < 70%, 0 ≤ Ta ≤ 10%, 0 ≤ Nb ≤ 10%, N ≥ 2%, and the balance being C; Let the average value of the particle equivalent circle diameter of the first cubic solid solution SS1 be D ss1 Let the average value of the particle equivalent circle diameter of the second cubic solid solution SS2 be D ss2 0.5 μm < D ss1 < 1.5 μm, 0.5 μm < D ss2 < 1.5 μm; The preparation method of the hard alloy comprises the following steps: (1) preparing raw materials: preparing raw materials according to the elements and proportions of the hard alloy; (2) compression molding: adding the above raw materials, molding agent, ball milling rod and alcohol into a ball mill for wet milling, drying and sieving the obtained slurry to obtain a mixture, and then compression molding into a green compact; (3) alloy sintering: heating the above green compact to 300-450 ℃ for H2 dewaxing and removing the molding agent PEG, then heating to 1300-1370 ℃ under vacuum, filling with 20-200 mbar inert gas Ar, sintering for 20-60 min, continuing to heat to 1420-1480 ℃ and holding for 30-120 min, then cooling to 1000-1200 ℃, and cooling to room temperature under H2 to obtain the hard alloy; In step (1), the raw material source of W element includes WC powder and / or (W, Ti)C solid solution powder, the raw material source of Ti element includes one or more of TiC powder, TiCN powder, (W, Ti)C solid solution powder and TiN powder, the raw material source of Ta element includes TaC powder and / or (Ta, Nb)C solid solution powder, the raw material source of Nb element includes NbC powder and / or (Ta, Nb)C solid solution powder, the source of N element includes TiCN powder and / or TiN powder, and the raw material source of Co element is Co powder; In step (1), the prepared raw materials include Co powder, (W, Ti)C solid solution powder, TiCN powder, (Ta, Nb)C solid solution powder and WC powder, and based on the total mass of the raw materials, the Co powder is 5-15%, the (W, Ti)C solid solution powder is 2-10%, the TiCN powder is 2-10%, the (Ta, Nb)C solid solution powder is 0-10%, and the balance is WC powder.

2. The cemented carbide according to claim 1, characterized in that, The first cubic solid solution SS1 comprises the following mass fractions of elements: 33% < W < 45%, 15% < Ti < 25%, 3% ≤ Ta < 25%, 3 ≤ Nb < 25%, 0 ≤ N < 2%, and the balance being C; and the second cubic solid solution comprises the following mass fractions of elements: 15% < W < 25%, 40% < Ti < 60%, 2% < Ta < 10%, 2% < Nb < 10%, N > 2%, and the balance being C.

3. The cemented carbide according to claim 1, characterized in that, The mass fraction of each phase in the hard alloy is: 5%≤Co binder phase≤15%, 0<first cubic solid solution SS1 and second cubic solid solution SS2≤25%, and the rest is WC phase.

4. The cemented carbide according to claim 3, characterized in that, The mass fraction of each phase in the hard alloy is: 5%≤Co binder phase≤10%, 5%<first cubic solid solution SS1 and second cubic solid solution SS2≤20%, and the rest is WC phase.

5. The cemented carbide according to claim 1, characterized in that, D ss2 <D ss1 .

6. The cemented carbide according to claim 1, characterized in that, The first cubic solid solution SS1 and the second cubic solid solution SS2 are discretely distributed in the hard alloy, the particle size of the first cubic solid solution SS1 is <15μm, and the particle size of the second cubic solid solution SS2 is <15μm.

7. The cemented carbide according to claim 6, characterized in that, The particle size of the first cubic solid solution SS1 is <10μm, and the particle size of the second cubic solid solution SS2 is <10μm.

8. The cemented carbide according to claim 7, characterized in that, The particle size of the first cubic solid solution SS1 is <7μm, and the particle size of the second cubic solid solution SS2 is <7μm.

9. A method of producing cemented carbide according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: (1) preparing raw materials: preparing raw materials according to the elements and proportions of the hard alloy; (2) pressing forming: adding the above-mentioned raw materials, forming agent, ball milling rod and alcohol into a ball mill for wet milling, drying and sieving the obtained slurry to obtain a mixture, and then pressing into a green body; (3) alloy sintering: heating the above-mentioned green body to 300-450℃ for H2 dewaxing and removing the forming agent PEG, then heating to 1300-1370℃ under vacuum conditions, filling 20-200mbar inert gas Ar, sintering for 20-60min, continuing to heat to 1420-1480℃ and holding for 30-120min, then cooling to 1000-1200℃, and cooling to room temperature under H2 conditions to obtain a hard alloy.

10. A method of producing cemented carbide according to claim 9, characterised in that, In step (1), the FSSS particle size of the Co powder is 1.2-1.5μm, the FSSS particle size of the (W, Ti)C solid solution powder is 1.5-2.0μm, the FSSS particle size of the TiCN powder is 0.8-1.2μm, the FSSS particle size of the (Ta, Nb)C solid solution powder is 1.0-1.5μm, and the FSSS particle size of the WC powder is 3.0-4.0μm.

11. A method of producing cemented carbide according to claim 9 or 10, c h a r a c t e r i s e d in that In step (2), the forming agent is PEG, the mass of the forming agent is 1.5-2.5% of the total mass of the raw materials in step (1), the mass of the ball milling rod is 4-6 times the total mass of the raw materials in step (1), the addition amount of alcohol is 200-300mL alcohol per kilogram of raw materials, and the wet milling time is 25-40h.

12. A method of producing cemented carbide according to claim 9 or 10, characterised in that, In step (2), the drying temperature is 60-120℃, the drying time is 2-3h, and the sieving is 60-80 mesh.

13. A method of producing cemented carbide according to claim 9 or 10, characterised in that, In step (3), the removing of the forming agent is implemented by TORVAC process.

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