High-toughness hard alloy and preparation method and application thereof

Abstract

The invention belongs to the technical field of powder metallurgy, and particularly relates to a high-toughness hard alloy and a preparation method and application thereof.The preparation method comprises the steps that tungsten powder is subjected to high-energy ball milling, and then treated tungsten powder is obtained; the preparation method comprises the following steps: dissolving water-soluble lanthanum salt, cerium salt and chromium salt, and performing spray drying to obtain La-Ce-Cr composite powder; the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder and carbon powder are mixed, and mixed powder is obtained; sintering the mixed powder to obtain alloy powder; the tungsten carbide and the alloy powder are flexibly mixed, and a mixture is obtained; and pressing and sintering the mixture to obtain the high-toughness hard alloy. The high-toughness hard alloy is a plate-shaped crystal hard alloy and is uniform in organization structure, the hardness HV10 is larger than or equal to 1620, and the fracture toughness KiC is larger than or equal to 24 MPa.m < 1 / 2 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder metallurgy, and specifically relates to a high-toughness cemented carbide and its preparation method and application. Background Art

[0002] Cemented carbides have the advantages of high hardness, wear resistance, corrosion resistance, etc., and are widely used in fields such as mining tools, die materials, cutting tools, wear-resistant parts, etc. Among them, cemented carbide inserts are widely used in the field of metal cutting due to their excellent hardness, wear resistance, and high-temperature performance. Among them, YT-type cemented carbides (mainly composed of WC-Co-TiC) are particularly suitable for high-speed cutting of steel and cast iron due to their good red hardness and resistance to crater wear. However, traditional YT-type inserts still have the following technical bottlenecks: (1) Insufficient impact toughness: Since YT-type alloys use TiC as the hard phase, their brittleness is relatively high, and chipping or fracture is likely to occur during interrupted cutting or high-load machining, affecting tool life and machining stability. (2) The contradiction between strength and hardness: Under traditional processes, WC grains are mostly equiaxed, which can improve hardness, but the grain boundary strength is relatively low, resulting in the generation of microcracks in the insert under high-temperature and high-pressure working conditions, reducing reliability.

[0003] In recent years, researchers have tried to improve the performance of YT-type alloys by refining grains, adding rare earth elements, or adjusting the proportion of the binder phase, but the effects are limited. For example: improving hardness by using nano-WC powder, but sacrificing toughness; optimizing stress distribution by adopting a gradient structure design, but the process is complex and the cost is high. The introduction of plate-like WC provides a new idea for solving the above problems. Plate-like WC has an anisotropic structure, which can enhance the fracture toughness of the material through the grain interlocking effect, and at the same time its aspect ratio can optimize the stress transmission path. However, in the existing technology, YT-type cemented carbides containing plate-like WC often have unstable toughness due to improper control of the plate-like crystal structure.

[0004] Therefore, there is an urgent need to develop a new type of YT-type cemented carbide insert that can significantly improve impact resistance and cutting stability while maintaining high hardness by controllably introducing plate-like WC and optimizing the TiC distribution to meet the requirements of modern high-efficiency machining. Summary of the Invention

[0005] To solve the problems existing in the prior art, the main object of the present invention is to propose a high-toughness cemented carbide and its preparation method and application.

[0006] According to the first aspect of the present invention, the following technical solutions are provided: A preparation method of a high-toughness cemented carbide, comprising the following steps: S1. High-energy ball milling tungsten powder to obtain treated tungsten powder; S2. Dissolve water-soluble lanthanum salt, cerium salt, and chromium salt, and then spray-dry to obtain La-Ce-Cr composite powder; S3. Mix the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder, and carbon powder to obtain a mixed powder; S4. Sinter the mixed powder to obtain alloy powder; S5. Flexibly mix tungsten carbide and alloy powder to obtain a mixture; S6. Press and sinter the mixture to obtain high-toughness cemented carbide.

[0007] According to the second aspect of the present invention, the present invention provides the following technical solution: A high-toughness cemented carbide is prepared by using the preparation method of the high-toughness cemented carbide described above. The high-toughness cemented carbide is plate-like crystal cemented carbide, with uniform microstructure, hardness HV10≥1620, and fracture toughness KiC≥24MPa·m 1 / 2 。

[0008] According to the third aspect of the present invention, the present invention provides the following technical solution: An application of the above high-toughness cemented carbide in the field of cutting inserts.

[0009] The beneficial effects of the present invention are as follows: The present invention provides a high-toughness cemented carbide, its preparation method and application. The preparation method includes: subjecting tungsten powder to high-energy ball milling to obtain treated tungsten powder; dissolving water-soluble lanthanum salt, cerium salt, and chromium salt and then spray-drying to obtain La-Ce-Cr composite powder; mixing the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder, and carbon powder to obtain a mixed powder; sintering the mixed powder to obtain alloy powder; flexibly mixing tungsten carbide and alloy powder to obtain a mixture; pressing and sintering the mixture to obtain high-toughness cemented carbide. The high-toughness cemented carbide is plate-like crystal cemented carbide, with uniform microstructure, hardness HV10≥1620, and fracture toughness KiC≥24MPa·m 1 / 2 。 BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0011] Figure 1 It is the metallographic diagram of the high-toughness cemented carbide prepared in Example 1 of the present invention; Figure 2This is the metallographic diagram of the cemented carbide prepared in Comparative Example 7 of the present invention.

[0012] The realization, functional characteristics and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific embodiments

[0013] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0014] According to the first aspect of the present invention, the following technical solutions are provided: A method for preparing a high-toughness cemented carbide, comprising the following steps: S1. High-energy ball-mill tungsten powder to obtain treated tungsten powder; S2. Dissolve water-soluble lanthanum salt, cerium salt and chromium salt and then spray-dry to obtain La-Ce-Cr composite powder; S3. Mix the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder and carbon powder to obtain a mixed powder; S4. Sinter the mixed powder to obtain alloy powder; S5. Flexibly mix tungsten carbide and alloy powder to obtain a mixture; S6. Press and sinter the mixture to obtain a high-toughness cemented carbide.

[0015] Preferably, in the step S1, by screening specific tungsten powder and performing high-energy ball milling to achieve flattening treatment, it provides a basic guarantee for the formation of plate-like crystal WC. With the induction of additives, the proportion of the plate-like crystal structure is further increased, and the alloy microstructure is optimized. The average FSSS particle size of the tungsten powder is ≥35 μm, D5≥13 μm, and span≤1.05. The ball-to-powder ratio during high-energy ball milling is (8-12):1, the ball milling speed is 280-420 r / min, and the ball milling time is 4-8 h. Specifically, the ball-to-powder ratio during high-energy ball milling can be any one of, for example, 8:1, 9:1, 10:1, 11:1, 12:1 or the range between any two of them; the ball milling speed can be any one of, for example, 280 r / min, 290 r / min, 300 r / min, 310 r / min, 320 r / min, 330 r / min, 340 r / min, 350 r / min, 360 r / min, 370 r / min, 380 r / min, 390 r / min, 400 r / min, 410 r / min, 420 r / min or the range between any two of them; the ball milling time can be any one of, for example, 4 h, 5 h, 6 h, 7 h, 8 h or the range between any two of them.

[0016] Preferably, in the step S2, by dissolving and spray-drying the water-soluble additive salt, an additive composite powder with uniform intermolecular mixing is prepared, providing conditions for subsequent uniform addition; lanthanum nitrate, cerium nitrate, and chromium nitrate are added to water for dissolution according to a mass ratio of 1:(1-2):(5-7), and then a La-Ce-Cr composite powder is prepared by spray drying; specifically, the mass ratio of lanthanum nitrate, cerium nitrate, and chromium nitrate can be any one of, for example, 1:1:5, 1:1:6, 1:1:7, 1:2:5, 1:2:6, 1:2:7 or the range between any two of them.

[0017] Preferably, in the step S3, the mass ratio of the treated tungsten powder, titanium dioxide powder, cobalt powder, and La-Ce-Cr composite powder is (56-68):(4-12):(6-10):(1.5-3.5); the addition amount of carbon powder is the sum of 0.0665-0.0672 times the mass of the treated tungsten powder and 0.75-0.90 times the mass of the titanium dioxide powder.

[0018] Preferably, in step S4, alloy powder is prepared by a specific sintering process, which ensures complete carbonization of Ti and W and provides a basis for the subsequent preparation of high-toughness cemented carbide. The sintering process is as follows: heating to 670 - 730 °C and holding for 1 - 2 h; then heating to 1160 - 1240 °C and holding for 2 - 3 h; then heating to 1900 - 2200 °C and holding for 4 - 6 h. Specifically, the first-stage holding temperature can be any one of, for example, 670 °C, 680 °C, 690 °C, 700 °C, 710 °C, 720 °C, 730 °C or the range between any two of them, and the first-stage holding time can be any one of, for example, 1 h, 1.25 h, 1.5 h, 1.75 h, 2 h or the range between any two of them; the second-stage holding temperature can be any one of, for example, 1160 °C, 1170 °C, 1180 °C, 1190 °C, 1200 °C, 1210 °C, 1220 °C, 1230 °C, 1240 °C or the range between any two of them, and the second-stage holding time can be any one of, for example, 2 h, 2.25 h, 1.5 h, 2.75 h, 3 h or the range between any two of them; the third-stage holding temperature can be any one of, for example, 1900 °C, 1950 °C, 2000 °C, 2050 °C, 2100 °C, 2150 °C, 2200 °C or the range between any two of them, and the third-stage holding time can be any one of, for example, 4 h, 4.5 h, 5 h, 5.5 h, 6 h or the range between any two of them.

[0019] Preferably, in step S5, by controllably adding tungsten carbide, cemented carbides and cemented carbide inserts with different compositions can be flexibly prepared. The average Fischer particle size of tungsten carbide is 1.8 - 3.2 μm, and the content of titanium carbide in the mixture is 4 - 10 wt%. Flexible mixing is carried out using a three-dimensional mixer. When flexibly mixing, the rotation speed of the mixer is 30 - 100 r / min, and the mixing time is 12 - 18 h. Specifically, the content of titanium carbide in the mixture can be any one of, for example, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt% or the range between any two of them; the rotation speed of the mixer during mixing can be any one of, for example, 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min or the range between any two of them; the mixing time can be any one of, for example, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h or the range between any two of them.

[0020] Preferably, in the step S6, the sintering process is as follows: the sintering temperature is 1480 - 1530 °C, the holding time is 2 - 4 h, and the sintering pressure is 7 - 9 MPa. Specifically, the sintering temperature can be, for example, any one of 1480 °C, 1490 °C, 1500 °C, 1510 °C, 1520 °C, 1530 °C or the range between any two of them; the holding time can be, for example, any one of 2 h, 2.5 h, 3 h, 3.5 h, 4 h or the range between any two of them; the sintering pressure can be, for example, any one of 7 MPa, 7.5 MPa, 8 MPa, 8.5 MPa, 9 MPa or the range between any two of them.

[0021] According to the second aspect of the present invention, the present invention provides the following technical solution: A high-toughness cemented carbide is prepared by using the preparation method of the above-mentioned high-toughness cemented carbide. The high-toughness cemented carbide is a plate-like crystal cemented carbide with uniform microstructure, hardness HV10 ≥ 1620, and fracture toughness KiC ≥ 24 MPa·m 1 / 2 。

[0022] According to the third aspect of the present invention, the present invention provides the following technical solution: An application of the above-mentioned high-toughness cemented carbide in the field of cutting blades.

[0023] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0024] Example 1 A preparation method of a high-toughness cemented carbide includes the following steps: S1. After high-energy ball milling tungsten powder, treated tungsten powder is obtained; the average FSSS particle size of the tungsten powder is 36.2 μm, D5 is 15.01 μm, and span is 1.01; the ball-to-material ratio during high-energy ball milling is 8:1, the ball milling speed is 280 r / min, and the ball milling time is 8 h; S2. Lanthanum nitrate, cerium nitrate, and chromium nitrate are added to water and dissolved according to a mass ratio of 1:1.5:6, and then La-Ce-Cr composite powder is prepared by spray drying; S3. The treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder, and carbon powder are mixed to obtain a mixed powder; the mass ratio of the treated tungsten powder, titanium dioxide powder, cobalt powder, and La-Ce-Cr composite powder is 60:8:8:2; the addition amount of the carbon powder is the sum of 0.0668 times the mass of the treated tungsten powder and 0.80 times the mass of the titanium dioxide powder; S4. The mixed powder is sintered to obtain alloy powder; the sintering process is as follows: heating to 700 °C and holding for 2 h; then heating to 1200 °C and holding for 2 h; then heating to 1900 °C and holding for 6 h; S5. Use a three-dimensional mixer to flexibly mix tungsten carbide and alloy powder to obtain a mixed material; the average Fisher particle size of tungsten carbide is 2.0 μm, and the content of titanium carbide in the mixed material is 6 wt%. When mixing, the rotation speed of the mixer is 50 r / min, and the mixing time is 16 h; S6. Press and sinter the mixed material. The sintering process is as follows: the sintering temperature is 1490 °C, the holding time is 3 h, and the sintering pressure is 8 MPa; a high-toughness cemented carbide is obtained.

[0025] The SEM image of the high-toughness cemented carbide prepared in this example is as shown in Figure 1 the figure. Its microstructure is uniform, the hardness HV10 is 1745, and the fracture toughness KiC is 25.9 MPa·m 1 / 2 .

[0026] Example 2 A method for preparing a high-toughness cemented carbide includes the following steps: S1. Subject tungsten powder to high-energy ball milling to obtain treated tungsten powder; the average FSSS particle size of tungsten powder is 37.2 μm, D5 is 13.8 μm, and span is 1.03; the ball-to-material ratio during high-energy ball milling is 12:1, the ball milling rotation speed is 420 r / min, and the ball milling time is 4 h; S2. Dissolve lanthanum nitrate, cerium nitrate, and chromium nitrate in water according to a mass ratio of 1:2:7, and then use spray drying to prepare La-Ce-Cr composite powder; S3. Mix the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder, and carbon powder to obtain a mixed powder; the mass ratio of the treated tungsten powder, titanium dioxide powder, cobalt powder, and La-Ce-Cr composite powder is 68:4:6:3.5; the addition amount of carbon powder is the sum of 0.0672 times the mass of the treated tungsten powder and 0.90 times the mass of the titanium dioxide powder; S4. Sinter the mixed powder to obtain alloy powder; the sintering process is as follows: heat up to 730 °C and hold for 1 h; then heat up to 1240 °C and hold for 2 h; then heat up to 2200 °C and hold for 4 h; S5. Use a three-dimensional mixer to flexibly mix tungsten carbide and alloy powder to obtain a mixed material; the average Fisher particle size of tungsten carbide is 3.1 μm, and the content of titanium carbide in the mixed material is 10 wt%. When mixing, the rotation speed of the mixer is 100 r / min, and the mixing time is 18 h; S6. Press and sinter the mixed material. The sintering process is as follows: the sintering temperature is 1530 °C, the holding time is 2 h, and the sintering pressure is 7 MPa; a high-toughness cemented carbide is obtained.

[0027] The microstructure of the high-toughness cemented carbide prepared in this example is uniform, the hardness HV10 is 1680, and the fracture toughness KiC is 25.4 MPa·m 1 / 2 .

[0028] Example 3 A preparation method of high-toughness cemented carbide, comprising the following steps: S1. Obtain treated tungsten powder by subjecting tungsten powder to high-energy ball milling; the average FSSS particle size of the tungsten powder is 38.32 μm, D5 is 15.72 μm, and span is 0.98; the ball-to-material ratio during high-energy ball milling is 10:1, the ball milling speed is 350 r / min, and the ball milling time is 6 h; S2. Dissolve lanthanum nitrate, cerium nitrate, and chromium nitrate in water according to a mass ratio of 1:1.5:5, and then prepare La-Ce-Cr composite powder by spray drying; S3. Mix the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder, and carbon powder to obtain a mixed powder; the mass ratio of the treated tungsten powder, titanium dioxide powder, cobalt powder, and La-Ce-Cr composite powder is 60:7:8:3.5; the addition amount of carbon powder is the sum of 0.0672 times the mass of the treated tungsten powder and 0.90 times the mass of the titanium dioxide powder; S4. Sinter the mixed powder to obtain alloy powder; the sintering process is: heat up to 670 °C and hold for 2 h; then heat up to 1160 °C and hold for 3 h; then heat up to 2200 °C and hold for 4 h; S5. Flexibly mix tungsten carbide and alloy powder using a three-dimensional mixer to obtain a mixed material; the average Fischer particle size of tungsten carbide is 2.6 μm, and the content of titanium carbide in the mixed material is 10 wt%. The rotation speed of the mixer during mixing is 100 r / min, and the mixing time is 12 h; S6. Press and sinter the mixed material, and the sintering process is: the sintering temperature is 1530 °C, the holding time is 2 h, and the sintering pressure is 9 MPa; obtain high-toughness cemented carbide.

[0029] The high-toughness cemented carbide prepared in this example has a uniform microstructure, a hardness HV10 of 1643, and a fracture toughness KiC of 27.64 MPa·m 1 / 2 .

[0030] Example 4 A preparation method of high-toughness cemented carbide, comprising the following steps: S1. Obtain treated tungsten powder by subjecting tungsten powder to high-energy ball milling; the average FSSS particle size of the tungsten powder is 35.24 μm, D5 is 13.73 μm, and span is 1.02; the ball-to-material ratio during high-energy ball milling is 10:1, the ball milling speed is 280 r / min, and the ball milling time is 4 h; S2. Dissolve lanthanum nitrate, cerium nitrate, and chromium nitrate in water according to a mass ratio of 1:1:5, and then prepare La-Ce-Cr composite powder by spray drying; S3. Mix the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder, and carbon powder to obtain a mixed powder. The mass ratio of the treated tungsten powder, titanium dioxide powder, cobalt powder, and La-Ce-Cr composite powder is 56:12:10:3.5. The addition amount of the carbon powder is the sum of 0.0665 times the mass of the treated tungsten powder and 0.75 times the mass of the titanium dioxide powder. S4. Sinter the mixed powder to obtain an alloy powder. The sintering process is as follows: heat up to 700 °C and hold for 1 h; then heat up to 1200 °C and hold for 3 h; then heat up to 1900 °C and hold for 6 h. S5. Flexibly mix tungsten carbide and the alloy powder using a three-dimensional mixer to obtain a mixed material. The average Fisher sub-sieve size of the tungsten carbide is 2.2 μm, and the titanium carbide content in the mixed material is 4 wt%. When mixing, the rotation speed of the mixer is 80 r / min, and the mixing time is 18 h. S6. Press and sinter the mixed material. The sintering process is as follows: the sintering temperature is 1480 °C, the holding time is 4 h, and the sintering pressure is 7 MPa; a high-toughness cemented carbide is obtained.

[0031] The high-toughness cemented carbide prepared in this example has a uniform microstructure, a hardness HV10 of 1720, and a fracture toughness KiC of 25.18 MPa·m 1 / 2 。

[0032] Comparative Example 1 The difference from Example 1 is that in step S1, the average FSSS particle size of the tungsten powder is 28.66 μm, D5 is 5.98 μm, and span is 1.02.

[0033] The cemented carbide prepared in this comparative example has a uniform microstructure, a hardness HV10 of 1730, and a fracture toughness KiC of 18.42 MPa·m 1 / 2 。

[0034] Comparative Example 2 The difference from Example 1 is that in step S1, the average FSSS particle size of the tungsten powder is 36.91 μm, D5 is 8.35 μm, and span is 1.34.

[0035] The cemented carbide prepared in this comparative example has abnormally grown coarse-grained WC, a hardness HV10 of 1553, and a fracture toughness KiC of 20.37 MPa·m 1 / 2 。

[0036] Comparative Example 3 The difference from Example 1 is that step S2 is not carried out, and lanthanum nitrate, cerium nitrate, and chromium nitrate are directly added and mixed in step S3.

[0037] The cemented carbide prepared in this comparative example has pores, abnormal growth of tungsten carbide grains, a hardness of HV10 of 1383, and a fracture toughness of KiC of 13.83 MPa·m 1 / 2 。

[0038] Comparative Example 4 The difference from Example 1 is that in step S3, the addition amount of carbon powder is the sum of 0.0665 times the mass of the treated tungsten powder and 0.5 times the mass of the titanium dioxide powder.

[0039] The cemented carbide prepared in this comparative example has pores, a hardness of HV10 of 1672, and a fracture toughness of KiC of 16.49 MPa·m 1 / 2 。

[0040] Comparative Example 5 The difference from Example 1 is that in step S4, the sintering process is: heating to 1900 °C and holding for 10 h.

[0041] The cemented carbide prepared in this comparative example has pores and a carbon-deficient phase appears, and abnormal growth of non-plate-shaped grains occurs. The hardness HV10 is 1576, and the fracture toughness KiC is 18.59 MPa·m 1 / 2 。

[0042] Comparative Example 6 The difference from Example 1 is that in step S5, wet ball milling is used for mixing.

[0043] The cemented carbide prepared in this comparative example has no plate-shaped crystal structure, a hardness of HV10 of 1739, and a fracture toughness of KiC of 13.66 MPa·m 1 / 2 。

[0044] Comparative Example 7 The difference from Example 1 is that the cemented carbide is prepared by a traditional method. Specifically, tungsten carbide powder, titanium carbide powder, and cobalt powder are wet ball milled in a mass ratio of 85:6:9, and then pressed and sintered to obtain the cemented carbide. The sintering process is the same as that in step S5 of Example 1.

[0045] The cemented carbide prepared in this comparative example has no plate-shaped crystal structure (as Figure 2 shown), a hardness of HV10 of 1432, and a fracture toughness of KiC of 14.85 MPa·m 1 / 2 。

[0046] The samples prepared in Example 1, Example 3, Comparative Example 2, Comparative Example 5, and Comparative Example 7 were subjected to cast iron cutting tests. The machine tool was a German DMG NLX4000 1750 type, the cutting speed was 260 m / min, the feed rate was 0.35 mm / r, and the cooling method was coolant wet machining. The test results are as follows. It can be seen that the high-toughness cemented carbide prepared by the present invention exhibits good performance in use. Under the conditions of rapid chip removal and high feed rate, it not only does not crack, but also has the performance of low wear.

[0047] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for preparing high-toughness cemented carbide, characterized in that: The steps include: S1. subjecting tungsten powder to high-energy ball milling to obtain treated tungsten powder; S2, dissolving water-soluble lanthanum salt, cerium salt and chromium salt and spray drying them to obtain La-Ce-Cr composite powder; S3, mixing the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder and carbon powder to obtain a mixed powder; S4, sintering the mixed powder to obtain alloy powder; S5, flexibly mixing tungsten carbide and alloy powder to obtain a mixture; S6. The mixed material is pressed and sintered to obtain a high-toughness cemented carbide.

2. The method for preparing high-toughness cemented carbide according to claim 1, characterized in that: In the step S1, the average FSSS particle size of the tungsten powder is ≥35 μm, D5 is ≥13 μm, and span is ≤1.05; the ball-to-material ratio during high-energy ball milling is (8-12):1, the ball milling speed is 280-420 r / min, and the ball milling time is 4-8 h.

3. The method for preparing high-toughness cemented carbide according to claim 1, characterized in that: In the step S2, lanthanum nitrate, cerium nitrate and chromium nitrate are added into water in a mass ratio of 1:(1-2):(5-7) to dissolve, and then spray drying is performed to prepare La-Ce-Cr composite powder.

4. The method for preparing high-toughness cemented carbide according to claim 1, characterized in that: In the step S3, the mass ratio of the processed tungsten powder, titanium dioxide powder, cobalt powder and La-Ce-Cr composite powder is (56-68): (4-12): (6-10): (1.5-3.5).

5. The method for preparing high-toughness cemented carbide according to claim 4, characterized in that: The amount of carbon powder added is the sum of 0.0665-0.0672 times the mass of the treated tungsten powder and 0.75-0.90 times the mass of the titanium dioxide powder.

6. The method for preparing high-toughness cemented carbide according to claim 1, characterized in that: In step S4, the sintering process is: heating to 670-730°C, keeping warm for 1-2 hours; then heating to 1160-1240°C, keeping warm for 2-3 hours; then heating to 1900-2200°C, keeping warm for 4-6 hours.

7. The method for preparing high-toughness cemented carbide according to claim 1, characterized in that: In step S5, the content of titanium carbide in the mixture is 4-10wt%; the speed of the mixer during mixing is 30-100r / min, and the mixing time is 12-18h.

8. The method for preparing high-toughness cemented carbide according to claim 1, characterized in that: In step S6, the sintering process is as follows: the sintering temperature is 1480-1530° C., the holding time is 2-4 hours, and the sintering pressure is 7-9 MPa.

9. A high-toughness cemented carbide, characterized in that: The high-toughness cemented carbide is prepared by the preparation method of any one of claims 1 to 8, wherein the high-toughness cemented carbide is a plate-shaped crystal cemented carbide with a uniform structure, a hardness HV10 ≥ 1620, and a fracture toughness KiC ≥ 24 MPa·m 1 / 2 .

10. Use of the high-toughness cemented carbide according to claim 9 in the field of cutting blades.

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