Non-magnetic hard alloy and preparation method and application thereof

Abstract

The invention discloses a non-magnetic hard alloy and a preparation method and application thereof.The non-magnetic hard alloy comprises a high-entropy binding phase and a hard phase, the component of the hard phase comprises WC, the component of the high-entropy binding phase comprises at least six of first transition metal elements and second transition metal elements, the first transition metal elements comprise Co, Ni and Fe, and the second transition metal elements comprise Co, Ni and Fe; the second transition metal elements comprise at least three or more of Cr, Re, Ru, Rh, Pd, Os, Ir and Pt, the mass percent of the high-entropy binding phase is 6-25%, and the balance is the hard phase, the hard alloy has very high comprehensive mechanical performance, and the problem that an existing non-magnetic hard alloy is insufficient in wear resistance is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, and in particular to a non-magnetic cemented carbide, its preparation method, and its applications. Background Technology

[0002] Non-magnetic alloys refer to hard alloy materials that have no magnetic properties or weak magnetic properties. Their superior performance allows them to replace non-magnetic steel, significantly improving work efficiency. With the development of society and the economy, and the advancement of hard alloy science and technology, the use of non-magnetic alloys will become increasingly widespread.

[0003] Non-magnetic cemented carbides use ferrous transition metals (cobalt (Co), nickel (Ni), and iron (Fe)) as binder phases. Fe, Co, and Ni are all magnetic, with Curie points of 770℃, 1120℃, and 354℃, respectively. Ni has a relatively low Curie point, which can be lowered below room temperature through various methods; using Ni as a binder is essential for producing non-magnetic alloys. However, compared to cemented carbides with pure Co binder phases, non-magnetic cemented carbides made with pure Ni as the binder phase exhibit significantly lower wear resistance.

[0004] The prior art discloses a non-magnetic cemented carbide comprising a binder phase and a hard phase. The hard phase is composed of WC, and the binder phase comprises Ni, Cu, Mo, and Cr. The non-magnetic cemented carbide is prepared by powder metallurgy. This literature uses Co, Ni, Cu, and Mo as the binder phase, which improves the wear resistance of the cemented carbide to a certain extent compared to pure Co or pure Ni binder phases. However, due to the low hardness of the binder phase, the hardness improvement of the non-magnetic cemented carbide prepared by this technology is relatively small. Therefore, there is a need to provide a non-magnetic cemented carbide with high density and high hardness. 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 high-density, high-hardness non-magnetic cemented carbide, its preparation method and application.

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

[0007] A non-magnetic cemented carbide comprises a high-entropy binder phase and a hard phase. The hard phase is composed of WC, and the high-entropy binder phase comprises at least six elements selected from a first transition metal element and a second transition metal element. The first transition metal element is Co, Ni, and Fe, and the second transition metal element is at least three or more selected from Cr, Re, Ru, Rh, Pd, Os, Ir, and Pt (Cr is an essential metal element in the second transition metal element, and at least two of the other metal elements are included). The mass percentage of the high-entropy binder phase is 6-25%, with the remainder being the hard phase. Let the mass percentages of Co, Ni, Fe, and Cr in the non-magnetic cemented carbide raw material be m, respectively.Co m Ni m Fe m Cr The condition M×8%≤m is satisfied. Cr ≤M×14%, M=m Co +m Ni +m Fe The atomic percentage of elements other than Cr in the high-entropy binder phase is 5-35%.

[0008] As a further improvement to the above technical solution:

[0009] The composition of the high-entropy binder phase in the non-magnetic cemented carbide satisfies the mixing entropy ΔS mix ≥1.61R,

[0010]

[0011] N represents the total number of atoms in the high-entropy binder phase alloy, r represents the number of elements in the high-entropy binder phase, and n0 to n r , where are the number of atoms of each element in the high-entropy binder phase, k is the Boltzmann constant, and R is the gas molar constant.

[0012] The components of the hard phase also include one or more of the nitrides, carbides and carbonitrides of the third transition element, wherein the third transition element includes one or more of Ta, Nb and Ti.

[0013] F of the first transition metal element raw material sss The particle size is not greater than 5 μm, and the F of the second transition metal element raw material sss Particle size not greater than 48μm.

[0014] The second transition metal element Cr raw material F sss Particle size not greater than 5μm.

[0015] The raw materials for the binder phase components of the non-magnetic hard alloy, except for Cr, are all elemental powders of the element, and the raw material for Cr is Cr3C2 powder.

[0016] A method for preparing a non-magnetic cemented carbide includes the following steps:

[0017] S1. The raw material powders of the non-magnetic hard alloy are wet-milled, dried, granulated and sieved to obtain a mixture.

[0018] S2. The mixture is shaped and sintered to obtain a non-magnetic hard alloy.

[0019] The wet milling process in step S1 includes the following steps:

[0020] The raw material powder of the high-entropy binder phase and the molding agent are wet-milled for 20-60 hours. The raw material powder of the hard phase is then added, and the mixture is continued to be ball-milled for 15-50 hours. The wet milling medium is anhydrous alcohol, and the mass of the wet milling medium is 0.28-0.35 times the total weight of the mixture.

[0021] In step S2, the sintering is vacuum sintering or high-pressure sintering, and the sintering temperature is 1450℃~1600℃.

[0022] In step S1, the weight of the ball milling rod used in wet milling is 10 to 20 times the total weight of the mixture.

[0023] In step S2, the sintering temperature is 1450℃~1550℃.

[0024] The purity of each raw material powder of the non-magnetic cemented carbide is not less than 99.90%.

[0025] The high-entropy binder phase comprises 10–25% by mass.

[0026] Application of the aforementioned non-magnetic cemented carbide or the non-magnetic cemented carbide prepared according to the aforementioned preparation method in non-magnetic molds, non-magnetic wear-resistant parts and non-magnetic cemented carbide cutting tools.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] The non-magnetic cemented carbide of the present invention comprises a high-entropy binder phase and a hard phase. The hard phase comprises WC, and the high-entropy binder phase comprises at least six elements selected from a first transition metal element and a second transition metal element. The first transition metal element includes Co, Ni, and Fe, and the second transition metal element includes at least three or more selected from Cr, Re, Ru, Rh, Pd, Os, Ir, and Pt. The mass percentage of the high-entropy binder phase is 6-25%, with the remainder being the hard phase. The at least six elements in the binder phase form a high-entropy alloy. Due to its high-entropy characteristics, the high-entropy binder phase has very high hardness, and the dissolution and precipitation of WC grains in the hard phase are controlled, resulting in finer WC grain size. Therefore, the cemented carbide exhibits high comprehensive mechanical properties, effectively solving the problem of insufficient wear resistance in existing non-magnetic cemented carbides. Let the mass percentages of Co, Ni, Fe, and Cr in the non-magnetic cemented carbide raw material be m, ... Co m Ni m Fe m Cr The condition M×8%≤m is satisfied. Cr ≤M×14%, M=m Co +m Ni +m FeThe atomic percentage of elements other than Cr in the high-entropy binder phase is 5-35%. Cr has a certain solid solubility in Co, Ni, or Fe. If the mass of Cr is large, a third phase will be produced; if the mass of Cr is small, a high-entropy binder phase cannot be formed. The present invention limits the mass of Co, Ni, Fe, and Cr so that a third phase is not produced while a high-entropy binder phase is formed.

[0029] The preparation method of the non-magnetic hard alloy of the present invention involves wet grinding followed by sintering. During the liquid-phase sintering stage, the various transition metal elements in the high-entropy binder phase are dissolved in liquid phase to form a high-entropy alloy, thus rendering the high-entropy binder phase non-magnetic. Furthermore, due to the liquid-phase sintering, the non-magnetic hard alloy of the present invention has a very high density and is free of porosity. Attached Figure Description

[0030] Figure 1 This is a metallographic photograph of the non-magnetic hard alloy of Embodiment 1 of the present invention. Detailed Implementation

[0031] The present invention will be further described in detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.

[0032] Example 1

[0033] A non-magnetic cemented carbide according to this embodiment includes a high-entropy binder phase and a hard phase. The hard phase comprises WC, and the high-entropy binder phase comprises six elements selected from a first transition metal element and a second transition metal element. The first transition metal element includes Co, Ni, and Fe, and the second transition metal element includes Cr, Re, and Ru. The mass percentage of the high-entropy binder phase is 11.8%, with the remainder being the hard phase. Let the mass percentages of Co, Ni, Fe, and Cr in the non-magnetic cemented carbide raw material be m, respectively. Co m Ni m Fe m Cr M = m Co +m Ni +m Fe m Cr = M × 9%, satisfying M × 8% ≤ m Cr ≤M×14%.

[0034] A method for preparing the non-magnetic hard alloy of this embodiment 1 includes the following steps:

[0035] B1. Raw material preparation: Prepare raw material powders according to Table 1: 881.5g WC powder, 23.8g Co powder, 23.8g Ni powder, 22.6g Fe powder, 7.3g Cr3C2 powder, 22.6g Re powder, and 18.4g Ru powder. The total weight of raw material powders is 1000g.

[0036] Table 1 Particle size and component weight of raw materials

[0037]

[0038]

[0039] B2. Add 15000g of ball milling rod to a wet mill, then add the binder phase raw material powder (Co powder, Ni powder, Fe powder, Cr3C2 powder, Re powder, Ru powder), add 20g of forming agent (PEG4000, polyethylene glycol), and use 400ml of anhydrous alcohol as the wet milling medium. Wet mill for 24 hours, then add WC powder and wet mill for 40 hours. Dry and granulate to obtain the mixture.

[0040] B3. Press the mixture into shape, and then perform pressure sintering. The maximum sintering temperature is 1465℃. At this sintering temperature, all raw materials except WC powder are melted into liquid, so it is also liquid phase sintering. The pressure of argon gas is 60 bar, and the high-pressure sintering is carried out for 80 minutes. After cooling to room temperature, a non-magnetic hard alloy is obtained.

[0041] Metallographic photographs of the non-magnetic cemented carbide obtained in this embodiment are as follows: Figure 1 As shown, the hard phase WC grain size D50 of this alloy is 0.35 μm. This alloy comprises a two-phase structure of a binder phase and a hard phase. Figure 1 The light-colored spots represent the binder phase, while the dark-colored areas represent the hard phase WC.

[0042] The energy spectrum of the binder phase of the non-magnetic hard alloy prepared in this embodiment is shown in Table 2. According to the energy spectrum data, the mixing entropy ΔS = 1.75R of the binder phase is calculated according to formula (1).

[0043]

[0044] In the above formula, N is the total number of atoms in the binder phase alloy, r is the number of elements in the binder phase, and n0 to n r denoted by , where represents the number of atoms of each element in the binder phase, and k is the Boltzmann constant, k = 1.38054 × 10⁻⁶. -23 J / K, where R is the gas molar constant, R = 8.31 J·K -1 ·mol -1 .

[0045] Table 2 Energy Spectra of the Binder Phase

[0046] element at.% Co 0.24 Ni 0.23 Fe 0.23 Cr 0.06 Re 0.03 Ru 0.10 W 0.11

[0047] Example 2

[0048] A non-magnetic cemented carbide of the present invention comprises a high-entropy binder phase and a hard phase. The hard phase comprises WC, and the high-entropy binder phase comprises six elements selected from a first transition metal element and a second transition metal element. The first transition metal element includes Co, Ni, and Fe, and the second transition metal element includes Cr, Re, and Os. The mass percentage of the binder phase is 11.9%, with the remainder being the hard phase. Let the mass percentages of Co, Ni, Fe, and Cr in the non-magnetic cemented carbide raw material be m, respectively. Co m Ni m Fe m Cr M = m Co +m Ni +m Fe m Cr = M × 9%, satisfying M × 8% ≤ m Cr ≤M×14%.

[0049] A method for preparing a non-magnetic cemented carbide according to this embodiment is substantially the same as that in Embodiment 1, and includes the following steps:

[0050] B1. Raw material preparation: Prepare the raw material powders according to Table 3: 870.7g WC powder, 10.0g TaNbC powder, 23.9g Co powder, 23.9g Ni powder, 22.6g Fe powder, 7.3g Cr3C2 powder, 18.5g Ru powder, and 23.1g Os powder. The total weight of the raw material powders is 1000g.

[0051] Table 3 Particle size and component weight of raw materials

[0052] Raw material name <![CDATA[F sss / μm]]> weight / g Co powder 0.9 23.9 Ni fans 2.2 23.9 Fe powder 1.5 22.6 <![CDATA[Cr3C2 powder]]> 1.2 7.3 Ru powder 3.0 18.5 Os powder 3.5 23.1 WC powder 0.8 870.7 TaNbC powder 1.5 10.0

[0053] B2. Add 15000g of ball milling rod to a wet mill, then add the above binder powders (Co powder, Ni powder, Fe powder, Cr3C2 powder, Ru powder, Os powder), add 20g of forming agent (PEG4000, polyethylene glycol), use 400ml of anhydrous alcohol as the wet milling medium, wet mill for 30h, then add WC powder and TaNbC powder, wet mill for 40h, dry and granulate to obtain the mixture.

[0054] B3. Press the mixture into shape and perform pressure sintering in an argon atmosphere. The maximum sintering temperature is 1480℃. At this sintering temperature, all raw materials except WC powder are melted into liquid, so it is also liquid phase sintering. The argon pressure is 60 bar and the sintering time is 80 min. Cool to room temperature to obtain a non-magnetic hard alloy.

[0055] The energy spectrum of the binder phase of the non-magnetic hard alloy prepared in this embodiment is shown in Table 4 below. According to the energy spectrum data, the mixing entropy ΔS = 1.81R of the binder phase is calculated according to formula (1).

[0056] Table 4 Energy Spectra of the Binder Phase

[0057]

[0058]

[0059] Comparative Example 1

[0060] A comparative example of cemented carbide is basically the same as that in Example 1, comprising a binder phase (non-high entropy alloy phase) and a hard phase. The hard phase comprises WC, and the binder phase comprises a first transition metal element and a second transition metal element. The first transition metal element comprises Ni, and the second transition metal element comprises Cr. The mass percentage of the binder phase is 10.6%, and the remainder is the hard phase.

[0061] A comparative method for preparing cemented carbide is basically the same as the method in Example 1, except that in step B1, the binder phase raw material powder is only Ni powder and Cr3C2 powder, which are 100.0g and 5.8g respectively, and the hard phase raw material powder WC powder is 894.2g.

[0062] Comparative Example 2

[0063] A non-magnetic hard alloy comprises a binder phase (a non-high-entropy alloy phase) and a hard phase. The hard phase is composed of WC, and the binder phase comprises Ni, Cu, Mo, and Cr. The binder phase has a mass percentage of 10.1%, with the remainder being the hard phase.

[0064] A method for preparing the comparative example cemented carbide is basically the same as the method in Example 1, including the following steps:

[0065] B1. Raw material preparation: The binder phase raw material powder consists of Ni powder, Cu powder, Cr3C2 powder and Mo2C powder. The raw material powder contains the following percentages by mass: WC powder: 89.9%, Ni powder: 7.2%, Cu powder: 0.8%, Cr3C2 powder: 0.6%, Mo2C powder: 0.5%, and the total mass of the raw material powder is 1 kg.

[0066] B2. Add a ball milling rod to a wet mill, then add the above binder phase powders (Ni powder, Cu powder, Cr3C2 powder and Mo2C powder), add 20g of forming agent, use 275ml of anhydrous ethanol as the ball milling medium, and the ball-to-material ratio is 5:1. After ball milling for 45 hours, spray dry to obtain the mixture.

[0067] B3. Press the mixture into shape and sinter it at a temperature of 1410℃, a furnace pressure of 6MPa, and a sintering time of 2h. Cool it to room temperature to obtain a non-magnetic hard alloy.

[0068] Comparative Example 3

[0069] A non-magnetic metal-ceramic material includes a binder phase (a non-high-entropy alloy phase) and a hard phase. The hard phase is a (W, Ti, Ta, Nb)(C, N) solid solution, and the binder phase comprises Ni, W, Cr, and Mo.

[0070] A method for preparing the comparative non-magnetic metal-ceramic material, as detailed in CN101890476B, includes the following steps:

[0071] B1. Preparation of binder phase raw materials: The binder phase raw material powder includes, by mass percentage, 12% Ni powder, 10% W powder, 6% Cr powder, and 7% Mo powder, with a total mass of 1000g.

[0072] B2. The binder phase raw material powder was dry-milled in a planetary ball mill for 28 hours with a ball-to-material ratio of 14:1 to obtain Ni-W-Cr-Mo presolution powder 3.

[0073] B3. Ni-W-Cr-Mo presolution powder and commercially available hard phase solid powder ((W,Ti,Ta,Nb)(C,N) presolution powder) are mixed in a mass percentage ratio of 35%:65% to form a presolution powder. The presolution powder is then wet-milled in a ball mill for 48 hours with 5% forming agent and a ball-to-material ratio of 5:1 to obtain a mixture.

[0074] B4. The mixture is molded, degreased and sintered to obtain a non-magnetic metal ceramic material.

[0075] The products obtained in Examples 1 and 2 and Comparative Examples 1, 2 and 3 were subjected to density, hardness, and bending strength tests. The test results are shown in Table 5. The density, hardness, and bending strength of the non-magnetic cemented carbide in Examples 1 and 2 of the present invention are all better than those of the comparative examples, indicating that the non-magnetic cemented carbide of the present invention has a very high density and no pore defects in its microstructure. Compared with Comparative Examples 1, 2 and 3, the non-magnetic cemented carbide of the present invention has a very high hardness, which can solve the problem of insufficient wear resistance of non-magnetic cemented carbide.

[0076] Table 5 Performance data of products in each embodiment

[0077]

[0078] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A non-magnetic cemented carbide comprising a high-entropy binder phase and a hard phase, characterized in that: The component of the hard phase comprises WC, the component of the high-entropy binder phase comprises at least six elements in the first transition metal element and the second transition metal element, the first transition metal element is Co, Ni, Fe, and the second transition metal element is at least three or more than three in Cr, Re, Ru, Rh, Pd, Os, Ir and Pt, the mass percentage of the high-entropy binder phase is 6-25%, and the rest is the hard phase; Let the mass of Co, Ni, Fe, Cr elements in the non-magnetic hard alloy raw material be m Co , m Ni , m Fe , m Cr , respectively, satisfying M*8%≤m Cr ≤M*14%, M=m Co +m Ni +m Fe , the atomic percentage of other elements in the component of the high-entropy binder phase except Cr is 5-35%.

2. The non-magnetic hard metal alloy according to claim 1, characterised in that: The composition of the high-entropy binder phase in the non-magnetic hard alloy satisfies a mixing entropy AS mix ≥ 1.61R, N is the total number of atoms in the high-entropy binder phase alloy, r is the number of elements in the high-entropy binder phase, n0 to n r are the number of atoms of each element in the high-entropy binder phase, respectively, k is the Boltzmann constant, and R is the gas molar constant.

3. The non-magnetic hard metal alloy according to claim 1, characterised in that: The component of the hard phase further comprises one or more than two of nitride, carbide and carbonitride of the third transition element, and the third transition element comprises one or more than two of Ta, Nb and Ti.

4. The non-magnetic hard metal alloy according to claim 1, characterised in that: F of the first transition metal element raw material is not more than 5 ppm sss F of the second transition metal element raw material is not more than 48 ppm sss F of the second transition metal element raw material is not more than 48 ppm 5. The non-magnetic hard metal alloy according to claim 1, characterised in that: F of the second transition metal element Cr raw material sss not more than 5 μm.

6. A method of producing a non-magnetic hard metal according to any one of claims 1 to 5, c h a r a c t e r i s e d in that: The method comprises the following steps: S1, wet grinding each raw material powder of the non-magnetic hard alloy, drying, granulating, screening to obtain a mixture; S2, the mixture is formed and liquid phase sintered to obtain the non-magnetic hard alloy.

7. The method of producing a non-magnetic hard metal alloy according to claim 6, characterized in that: The wet grinding in step S1 comprises the following steps: The raw material powder of the high-entropy binder phase is wet ground with a forming agent for 20-60 hours, the raw material powder of the hard phase is added, and the wet grinding is continued for 15-50 hours, the wet grinding medium is anhydrous alcohol, and the mass of the wet grinding medium is 0.28-0.35 times the total weight of the mixture.

8. The method of producing a non-magnetic hard metal alloy according to claim 6, characterized in that: In step S2, the liquid phase sintering is vacuum sintering or high-pressure sintering, and the temperature of the liquid phase sintering is 1450-1600 DEG C.

9. The application of the non-magnetic hard alloy prepared by the preparation method of the non-magnetic hard alloy according to any one of claims 1-5 or the non-magnetic hard alloy according to any one of claims 6-8 in non-magnetic molds, non-magnetic wear-resistant parts and non-magnetic hard alloy cutters.

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