Cemented carbide and cutting tool comprising the same as a base material

Abstract

A cemented carbide comprising a first hard phase composed of tungsten carbide particles and a binder phase composed of cobalt, nickel, iron, and copper as constituent elements, the average content ratio of each of the constituent elements in the binder phase being all 10 atomic % or more and 30 atomic % or less, not containing a second hard phase or the content of the second hard phase being 2 mass % or less relative to the total amount of the cemented carbide, the second hard phase being composed of a compound containing one or more metal elements selected from the group consisting of a Group 4 element, a Group 5 element, and a Group 6 element other than tungsten and one or more elements selected from the group consisting of carbon, nitrogen, and oxygen.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a cemented carbide and a cutting tool including the cemented carbide as a base material. BACKGROUND

[0002] Conventionally, a cemented carbide having a hard phase mainly composed of tungsten carbide (WC) and a binder phase mainly composed of an iron group element (for example, Fe, Co, Ni) has been used as a material for a cutting tool. The cutting tool is required to have strength (for example, bending strength), toughness (for example, fracture toughness), hardness (for example, Vickers hardness), plastic deformation resistance, wear resistance, and the like.

[0003] In addition, researches on high entropy alloys (HEA) composed of four or more metal elements and containing each element in an equal molar ratio or a ratio close to the equal molar ratio are being conducted. It is known that HEA exhibits an improvement in various mechanical properties by combining numerous metal elements. For example, Patent Document 1 (Japanese Patent Application Publication No. 2009-074173) discloses an HEA obtained by combining C, Si, Al, Cr, Co, Cu, Fe, Ni, V, Mn, Ti, and the like as constituent elements of a cemented carbide, and Patent Document 2 (Japanese Patent Application Publication No. 2019-516007) discloses an HEA obtained by combining Co, Cr, Cu, W, Fe, Ni, Mo, Mn, and the like as constituent elements of a cemented carbide.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-074173

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-516007 SUMMARY

[0008] Cemented carbide according to the present disclosure

[0009] a cemented carbide including a first hard phase and a binder phase,

[0010] the first hard phase is composed of tungsten carbide particles,

[0011] the binder phase is composed of cobalt, nickel, iron, and copper as constituent elements,

[0012] the average content ratio of each of the constituent elements in the binder phase is 10 atomic% or more and 30 atomic% or less,

[0013] the second hard phase is not included, or the content of the second hard phase with respect to the total amount of the cemented carbide is 2 mass% or less,

[0014] The second hard phase described above is composed of a compound containing one or more metal elements selected from the group consisting of a Group 4 element, a Group 5 element, and a Group 6 element other than tungsten, and one or more elements selected from the group consisting of carbon, nitrogen, and oxygen.

[0015] The cutting tool according to the present disclosure contains the cemented carbide according to the present disclosure as a base material. BRIEF DESCRIPTION OF DRAWINGS

[0016] [ Figure 1 ] Figure 1 is a schematic cross-sectional view for explaining the evaluation of the reaction resistance of the cemented carbide according to the present embodiment. DETAILED DESCRIPTION

[0017] [PROBLEMS TO BE SOLVED BY THE PRESENT DISCLOSURE]

[0018] In recent years, it is desired to improve the cutting efficiency of cutting processing of difficult-to-cut materials typified by Ni-based alloys such as Inconel (registered trademark) and Hastelloy (registered trademark). However, the component Ni contained in the above-mentioned difficult-to-cut materials easily diffuses with the component WC or Co contained in the conventional hard tool materials disclosed in Patent Literature 1 and Patent Literature 2. When the mutual diffusion occurs, the wear resistance of the cutting tool decreases, and the life of the cutting tool shortens. Therefore, compared to the case of cutting processing of iron-based materials (for example, steel), the life of the cutting tool tends to become extremely short in the case of cutting processing of difficult-to-cut materials.

[0019] The present disclosure was completed in view of the above-mentioned circumstances, and aims to provide a cemented carbide excellent in wear resistance when processing difficult-to-cut materials, particularly alloys containing Ni-based alloys, and a cutting tool containing the cemented carbide as a base material.

[0020] [EFFECTS OF THE PRESENT DISCLOSURE]

[0021] According to the present disclosure, it is possible to provide a cemented carbide excellent in wear resistance and a cutting tool containing the cemented carbide as a base material.

[0022] [EXPLANATION OF EMBODIMENTS OF THE PRESENT DISCLOSURE]

[0023] First, the content of one embodiment of the present disclosure is exemplified and explained.

[0024] [1] CEMENTED CARBIDE ACCORDING TO ONE EMBODIMENT OF THE PRESENT DISCLOSURE

[0025] is a cemented carbide containing a first hard phase and a binder phase,

[0026] the first hard phase described above is composed of tungsten carbide particles,

[0027] The above-described combined phase is composed of cobalt, nickel, iron, and copper as constituent elements,

[0028] The average content ratio of each of the above-described constituent elements in the above-described combined phase is all 10 atomic % or more and 30 atomic % or less,

[0029] The second hard phase is not included, or the content of the above-described second hard phase is 2 mass % or less with respect to the total amount of the hard alloy,

[0030] The above-described second hard phase is composed of a compound containing one or more metal elements selected from the group consisting of a Group 4 element, a Group 5 element, and a Group 6 element other than tungsten, and one or more elements selected from the group consisting of carbon, nitrogen, and oxygen.

[0031] The above-described hard alloy, by having the above-described constitution, is difficult to cause mutual diffusion between Ni contained in the Ni-based alloy and WC or Co contained in the hard alloy. As a result, the above-described hard alloy becomes a hard alloy excellent in wear resistance with respect to a machined material containing a Ni-based alloy.

[0032] [2] Preferably, in any cross section of the above-described hard alloy,

[0033] When a region in which the proportion of the content ratio of at least one of the above-described constituent elements with respect to the average content ratio is 85% or less and 115% or more is regarded as a non-uniform region,

[0034] The total area of the above-described non-uniform regions in the above-described combined phase is 6% or less with respect to the entire area of the above-described combined phase. By such a provision, the above-described hard alloy becomes a hard alloy more excellent in wear resistance with respect to a Ni-based alloy.

[0035] [3] One embodiment of the present disclosure relates to a cutting tool including the hard alloy described in any one of the above-described [1] or [2] as a base material. The above-described cutting tool, since it includes a hard alloy excellent in wear resistance with respect to a Ni-based alloy as a base material, can achieve long life of the cutting tool and the like even in the case of being used for cutting processing of a difficult-to-cut material containing a Ni-based alloy.

[0036] [4] The above-described cutting tool preferably further has a coating film provided on the above-described base material. By providing a coating film on the surface of the base material, it is possible to further improve the wear resistance and the like of the cutting tool. Thus, the above-described cutting tool can cope with more severe cutting conditions, and achieve further long life and the like.

[0037] [Details of Embodiments of the Present Disclosure]

[0038] Hereinafter, one embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described. However, the present embodiment is not limited to this.

[0039] "Hard alloy"

[0040] The hard alloy of the present embodiment is a hard alloy including a first hard phase and a binder phase,

[0041] The first hard phase described above is composed of tungsten carbide particles,

[0042] The binder phase described above is composed of cobalt, nickel, iron, and copper as constituent elements,

[0043] The average content ratio of each of the constituent elements in the binder phase described above is all 10 atomic% or more and 30 atomic% or less,

[0044] The second hard phase is not included, or the content of the second hard phase described above with respect to the total amount of the hard alloy described above is 2 mass% or less,

[0045] The second hard phase described above is composed of a compound containing one or more metal elements selected from the group consisting of a Group 4 element, a Group 5 element, and a Group 6 element other than tungsten, and one or more elements selected from the group consisting of carbon, nitrogen, and oxygen.

[0046] <Composition of hard alloy>

[0047] The hard alloy of the present embodiment is a hard alloy including a first hard phase and a binder phase, and sometimes includes a second hard phase. In addition, sometimes an element not belonging to any of the first hard phase, the binder phase, and the second hard phase is contained.

[0048] <First hard phase>

[0049] The first hard phase is composed of tungsten carbide (hereinafter sometimes referred to as "WC") particles. Here, the WC includes not only "pure WC (WC completely free of any impurity element and WC containing an impurity element below the detection limit)" but also "a first hard phase intentionally or unavoidably containing other impurity elements inside thereof within a range not impairing the effects of the present disclosure". The concentration of the impurity contained in the WC (the total concentration of them in the case where the elements constituting the impurity are two or more) with respect to the total amount of the WC described above and the impurity described above is 1 mass% or less.

[0050] (Average particle diameter of WC particles)

[0051] The average particle diameter of the WC particles in the cemented carbide is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 3 μm or less. By making the average particle diameter of the WC particles in the cemented carbide 0.1 μm or more, the toughness of the cemented carbide tends to be high. Therefore, the cutting tool including the cemented carbide as a base material can suppress chipping or damage due to mechanical impact and thermal impact. In addition, since the cutting tool is improved in crack propagation resistance, the propagation of cracks can be suppressed, and thus chipping or damage can be suppressed. On the other hand, by making the average particle diameter 10 μm or less, the hardness of the cemented carbide tends to be high. Therefore, the cutting tool including the cemented carbide as a base material can suppress deformation at the time of cutting, and thus can suppress wear or damage.

[0052] Here, the average particle diameter of the WC particles in the cemented carbide is obtained by mirror polishing an arbitrary surface or an arbitrary cross section of the cemented carbide, taking a photograph of the polished surface using a microscope, and performing image analysis on the photographed image. Specifically, the particle diameter (Heywood diameter: equivalent circle diameter of area) of each WC particle is calculated from the photographed image, and the average value thereof is taken as the average particle diameter of the WC particles. The number of the measured WC particles is preferably 100 or more, more preferably 200 or more. In addition, in the same cemented carbide, the image analysis is preferably performed under a plurality of fields of view, and the average value thereof is taken as the average particle diameter of the WC particles. The number of the fields of view in which the image analysis is performed is preferably 5 or more, more preferably 7 or more, further preferably 10 or more, and more further preferably 20 or more. One field of view can be, for example, a square of 20 μm x 20 μm.

[0053] As a method of mirror polishing, for example, a method using diamond paste, a method using a focused ion beam device (FIB device), a method using a cross-section polishing device (CP device), and a method combining them can be given. In the case where the polished surface is photographed using a metal microscope, the polished surface is preferably etched with Murakami reagent.

[0054] As a kind of microscope, a metal microscope, a scanning transmission electron microscope (SEM), and the like can be given. An image (microscope image) photographed using the microscope is input to a computer, and analyzed using image analysis software, and various information such as the average particle diameter is obtained. At this time, the WC particles constituting the first hard phase, the binder phase described later, and the second hard phase described later can be respectively identified by the following methods.

[0055] As to the identification of the first hard phase, the bonding phase, and the second hard phase, the above-described microscope image can be subjected to 2-value processing by using image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation) as image analysis software. Here, the 2-value processing refers to processing in which the concentration of each pixel is converted into two values of 1 and 0 by a certain reference value (threshold value). In the 2-value processing of the present disclosure, discriminant analysis is used.

[0056] (Area ratio of the first hard phase)

[0057] The area ratio of the first hard phase in any surface or any cross section of the cemented carbide according to the present embodiment is preferably 70% or more and 99% or less, more preferably 86% or more and 95% or less.

[0058] As to the area ratio of the first hard phase, for example, as in the case of obtaining the average particle diameter of the WC particles, any machined surface of the cemented carbide is imaged by a microscope, and the imaged image is subjected to image analysis to obtain the area ratio. That is, for the microscope image, 2-value processing for identifying the WC particles is performed using image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation) to obtain a 2-value image. Here, the 2-value processing is performed, for example, based on the brightness of the pixels. The threshold value of the brightness in the 2-value processing is a value obtained by multiplying a value extracted from an arbitrary point in the vicinity of the center of the first hard phase particle that appears darkest in the image by 0.8. From the 2-value image, the sum of the areas of the WC particles in the microscope image (total area) is calculated, and divided by the area of the entire field of view (2-value image), whereby the area ratio of the first hard phase in the field of view can be calculated. Then, in the same cemented carbide, the above-described image analysis can be performed in a plurality of fields of view (for example, three or more fields of view), and the average value thereof is regarded as the area ratio of the first hard phase in the entire surface or cross section of the cemented carbide. Note that the "predetermined field of view" can be the same as that in the case of obtaining the average particle diameter of the WC particles.

[0059] (Bonding phase)

[0060] The bonding phase is a phase in which the WC particles constituting the first hard phase, the compound particles constituting the second hard phase described later, or the WC particles constituting the first hard phase and the compound particles constituting the second hard phase are bonded to each other. The content ratio of the bonding phase is 4% by mass or more and 15% by mass or less based on the above-described cemented carbide. The bonding phase is composed of cobalt (Co), nickel (Ni), iron (Fe), and copper (Cu) as constituent elements.

[0061] In the present disclosure, Cu is used for the constituent element of the bonding phase because a large amount of chromium (Cr) is contained in the Ni-based alloy, and in the case where Cr is contained in the bonding phase, the wear resistance deteriorates due to interdiffusion of Cr. In addition, since it is difficult to form carbides and nitrides in the cemented carbide, Cu is used. Therefore, from the viewpoint of the wear resistance of the Ni-based alloy, it is most suitable in the present disclosure that Cr is not contained and Cu is contained in the bonding phase.

[0062] The average content ratio of each of Co, Ni, Fe, and Cu in the above bonding phase with respect to the total amount of Co, Ni, Fe, and Cu is all 10 atomic % or more and 30 atomic % or less (hereinafter referred to as "(at%)"). By doing so, a cemented carbide that does not have a heterogeneous phase precipitated and has excellent wear resistance with respect to the Ni-based alloy can be obtained. In addition, the content ratio of Co and Ni contained in the above bonding phase is preferably 25 at% or more and 30 at% or less, and the content ratio of Fe and Cu contained in the above bonding phase is preferably 20 at% or more and 25 at% or less. By being in the above range, the density of the above cemented carbide is improved, and the hardness tends to be improved.

[0063] The atomic concentration of Co, Ni, Fe, and Cu contained in the bonding phase can be measured using ICP emission spectrometry (Inductively Coupled Plasma emission spectrometry) (hereinafter sometimes referred to as "ICP measurement"). The present inventors believe that the above atomic concentration measured by ICP measurement is the atomic concentration after the entire bonding phase is averaged. Note that in the case where the surface of the above cemented carbide is covered with a coating film such as ceramic or diamond-like carbon, the coating film is preferably removed by grinding processing or the like.

[0064] (Area ratio of bonding phase)

[0065] In any surface or any cross section of the cemented carbide related to the present embodiment, the area ratio of the above bonding phase is preferably 1% or more and 30% or less, and more preferably 4% or more and 15% or less. By making the area ratio of the above bonding phase 1% or more and 30% or less, sufficient hardness and density can be ensured when used for a cutting tool. In addition, by making the area ratio of the above bonding phase 4% or more and 15% or less, the hardness and toughness of the above cemented carbide can be further ensured.

[0066] Note that, as with the measurement of the area ratio of the binder phase and the area ratio of the first hard phase, the 2-value image is obtained by performing 2-value processing using the image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation). The threshold value of the brightness in the 2-value processing is a value obtained by multiplying the value extracted from an arbitrary point of the interface of the binder phase that appears brightest in the image with the other phases by 1.2. From the 2-value image described above, the sum of the areas of the binder phase (Co, Ni, Fe, and Cu particles) in the microscope image (total area) is calculated, and the area ratio of the binder phase in the entire field of view (2-value image) is calculated. Then, in the same cemented carbide, the image analysis described above can be performed in a plurality of fields of view (for example, 3 or more fields of view), and the average value thereof is regarded as the area ratio of the binder phase in the entire surface or cross section of the cemented carbide.

[0067] (Area ratio of uneven regions in the binder phase)

[0068] In one aspect of the embodiment, when the region in which the proportion of the ratio of the content ratio of at least one of the constituent elements described above to the average content ratio is 85% or less and 115% or more is regarded as an uneven region in any cross section of the cemented carbide described above, the total area of the uneven regions in the binder phase described above with respect to the area of the entire binder phase is preferably 6% or less, and more preferably 3% or less. This indicates that the composition deviation in the binder phase of the entire cemented carbide is small. When the ratio exceeds 6%, the wear resistance of the Ni-based alloy tends to deteriorate.

[0069] (Image capturing)

[0070] The ratio described above can be calculated by the following method. That is, an arbitrary cross section obtained using a focused ion beam device (FIB device), a cross section polishing device (CP device), or the like is captured at 5000 times using a scanning transmission electron microscope (SEM) to obtain an electron image of an arbitrary number of sheets (for example, 10 or more sheets).

[0071] (2-value processing)

[0072] The electron image described above is subjected to 2-value processing using, for example, the image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation) to obtain a 2-value image. The threshold value of the brightness in the 2-value processing is a value obtained by multiplying the value extracted from an arbitrary point of the interface of the binder phase that appears brightest in the image with the other phases by 1.2. From the 2-value image described above, the binder phase is detected.

[0073] (Calculation of concentration)

[0074] For the detected bonding phase described above, an electron beam microanalyzer (EPMA) or energy dispersive X-ray spectroscopy (EDS) attached to the SEM is used to perform element mapping on a predetermined area (for example, 12 μm x 9 μm). In the element mapping described above, a phase containing WC is regarded as a first hard phase, and a phase containing Co, Ni, Fe, and Cu is regarded as a bonding phase. Note that the first hard phase and the bonding phase described above have clear boundaries and light and dark in the image captured by the SEM, and the bright phase can be regarded as the first hard phase, and the dark phase can be regarded as the bonding phase.

[0075] In the element mapping described above, when the ratio of the content ratio of any one of Co, Ni, Fe, and Cu is higher or lower than that of other areas of the bonding phase is detected, point analysis is performed near the center of the area of the bonding phase, and the content ratio of each element is calculated when the total amount of the measured values of Co, Ni, Fe, and Cu is 100. The content ratio is compared with the content ratio of each element calculated by the ICP emission spectroscopy described above, and in the case where the difference between the two content ratios is 85% or less and 115% or more, the area of the bonding phase is calculated using image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation), and thus the area ratio in the entire cemented carbide described above can be calculated. Then, in the same bonding phase, the image analysis described above can be performed in multiple fields of view (for example, 3 or more), and the average value thereof is regarded as the area ratio of the bonding phase.

[0076] <Second Hard Phase>

[0077] The cemented carbide according to the present embodiment does not contain a second hard phase, or the content of the second hard phase described above is 2% by mass or less with respect to the total amount of the cemented carbide described above, and preferably does not contain the second hard phase described above. In the case where the cemented carbide described above contains the second hard phase described above, it can be considered that the hard phase added within a range that does not hinder the effects of the present application, and that the second hard phase described above is not added as a raw material but is a substance inevitably generated in the manufacturing process.

[0078] The second hard phase is composed of a compound (composite compound) containing "one or more metal elements selected from the group consisting of a Group 4 element, a Group 5 element, and a Group 6 element other than tungsten" and "one or more elements selected from the group consisting of carbon (C), nitrogen (N), and oxygen (O)". As the Group 4 element, titanium (Ti), zirconium (Zr), hafnium (Hf), and the like can be listed. As the Group 5 element, vanadium (V), niobium (Nb), tantalum (Ta), and the like can be listed. As the Group 6 element, chromium (Cr), molybdenum (Mo), and the like can be listed. The compound is mainly a carbide, a nitride, a carbonitride, an oxide, or the like of the metal element described above.

[0079] The second hard phase is a compound phase or a solid solution phase composed of one or more of the above-mentioned compounds. Here, the "compound phase or solid solution phase" means that the compound constituting the phase can form a solid solution or can exist as each compound without forming a solid solution.

[0080] As a specific second hard phase, for example, there can be mentioned compounds such as TaC, NbC, TiC, TiCN, Cr3C2, Cr7C3, Al2O3, and SiO2.

[0081] (Mass ratio of the second hard phase)

[0082] In the case where the above-mentioned cemented carbide contains the above-mentioned second hard phase, the content of the above-mentioned second hard phase is preferably 2 mass% or less with respect to the above-mentioned cemented carbide. When the content of the above-mentioned second hard phase exceeds 2 mass%, the behavior of the solid solution reprecipitation in the sintering process changes, tending to hinder the constitution of the above-mentioned cemented carbide. In addition, even if Cr is solid-solved in the binder phase, it is difficult to be solid-solved in the phase containing Cu, and therefore the composition of the binder phase tends to be biased. Furthermore, due to the mutual diffusion of Cr contained in a large amount in the Ni-based alloy, the wear resistance tends to deteriorate.

[0083] (Area ratio of the second hard phase)

[0084] In any surface or any cross section of the above-mentioned cemented carbide, the area ratio of the above-mentioned second hard phase is preferably 1.5% or less.

[0085] Note that, as with the measurement of the area ratio of the first hard phase, the area ratio of the second hard phase is measured using the image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation) to perform 2-value processing, thereby obtaining a 2-value image. The threshold value of the brightness in the 2-value processing is a value obtained by multiplying a value extracted from the phase other than the first hard phase that becomes the detection target in the 2-value processing of the first hard phase by 0.8. From the 2-value image, the sum of the areas of the second hard phase (total area) in the microscopic image is calculated, and the total area is divided by the area of the entire field of view (2-value image), whereby the area ratio of the second hard phase in the field of view can be calculated. Then, in the same cemented carbide, the image analysis described above can be performed in a plurality of fields of view (for example, three or more fields of view), and the average value thereof is regarded as the area ratio of the second hard phase in the entire surface or cross section of the cemented carbide. It is obvious to those skilled in the art that, in the measurement described above, the area ratio of the cross section at a predetermined position from the surface of the cemented carbide is calculated. The predetermined position is, for example, set to a portion that is 50% of the thickness of the sample to be measured, and is preferably set to a portion that is 500 μm from the surface, in particular. In addition, it is obvious to those skilled in the art that, since the area ratio of the second hard phase in the surface portion of the cemented carbide sometimes varies, the measurement is performed avoiding the surface.

[0086] Method for manufacturing cemented carbide

[0087] The cemented carbide of the present embodiment can be typically manufactured by sequentially performing a raw material powder preparation step, a mixing step, a molding step, and a sintering step. Hereinafter, each step is described.

[0088] <Preparation step>

[0089] The preparation step is a step of preparing all of the raw material powders that constitute the material of the cemented carbide. For example, as the raw material powder of the first hard phase, WC particles can be listed. In addition, as the raw material of the binder phase, (i) particles in which Co, Ni, Fe, and Cu are alloyed in a predetermined composition (hereinafter sometimes referred to as "CoNiFeCu alloy particles"), (ii) Co particles and particles in which Ni, Fe, and Cu are alloyed in a predetermined composition (hereinafter sometimes referred to as "NiFeCu alloy particles"), or (iii) a case where Co particles, Ni particles, Fe particles, and Cu particles are used individually can be listed.

[0090] As the constituent elements of the binding phase, Co, Ni, Fe, and Cu can be used individually as (i) CoNiFeCu alloy particles, (ii) Co particles and NiFeCu alloy particles, or (iii) Co particles, Ni particles, Fe particles, and Cu particles, respectively, with (i) CoNiFeCu alloy particles being preferred. When Co, Ni, Fe, and Cu are added as raw material powders of the individual elements, or when Ni, Fe, and Cu are added as raw material powders of the individual elements, diffusion in the liquid phase is insufficient at a low sintering temperature, and a concentration difference is generated in the binding phase, which cannot result in a dense alloy. Note that since Co has good wettability with WC particles in the liquid phase, Co as the individual element can be used as a raw material.

[0091] (WC particles)

[0092] The WC particles used as the raw material are not particularly limited, and WC particles commonly used for manufacturing cemented carbides can be used. Commercially available WC particles can also be used. As commercially available WC particles, for example, the "Uniform Particle Tungsten Carbide Powder" series manufactured by A.L.M.T. Corp. can be cited.

[0093] The average particle diameter of the WC particles used as the raw material is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 3 μm or less. By making the average particle diameter of the WC particles used as the raw material 0.1 μm or more, the toughness tends to be high when the cemented carbide is formed. Therefore, the cutting tool containing the cemented carbide as the base material can suppress chipping and defects caused by mechanical and thermal shocks. In addition, since the cutting tool has improved resistance to crack propagation, the propagation of cracks can be suppressed, thereby suppressing chipping and defects. On the other hand, by making the average particle diameter 10 μm or less, the hardness tends to be high when the cemented carbide is formed. Therefore, the cutting tool containing the cemented carbide as the base material can suppress deformation at the time of cutting, and suppress wear and defects.

[0094] (CoNiFeCu alloy particles)

[0095] The following particles are used to produce particles in which Co, Ni, Fe, and Cu are alloyed in a predetermined composition (CoNiFeCu alloy particles). As a method for producing CoNiFeCu alloy particles, for example, a mechanical method, a chemical method, an atomization method, and the like can be cited, and the atomization method is preferred. In the atomization method, a metal that is an alloy is dissolved, and the dissolved metal (melt) is scattered and solidified to form a powder. The powder is adjusted to a target particle diameter, and uniformly mixed, whereby an alloy can be obtained.

[0096] The Co particles as a raw material are not particularly limited, and Co particles generally used for manufacturing cemented carbides can be used. As the Co particles, for example, particles composed of Co single substance can be mentioned. Commercially available products can also be used as the Co particles.

[0097] The Ni particles as a raw material are not particularly limited, and Ni particles generally used for manufacturing cemented carbides can be used. As the Ni particles, for example, particles composed of Ni single substance can be mentioned. Commercially available products can also be used as the Ni particles.

[0098] The Fe particles as a raw material are not particularly limited, and Fe particles generally used for manufacturing cemented carbides can be used. As the Fe particles, for example, particles composed of Fe single substance can be mentioned. Commercially available products can also be used as the Fe particles.

[0099] The Cu particles as a raw material are not particularly limited, and Cu particles generally used for manufacturing cemented carbides can be used. As the Cu particles, for example, particles composed of Cu single substance can be mentioned. Commercially available products can also be used as the Cu particles.

[0100] The concentration of impurities contained in the Co particles, Ni particles, Fe particles and Cu particles (the total concentration of the elements constituting the impurities when the elements are two or more) is 2% by mass or less with respect to the total amount of each of the particles and the impurities.

[0101] The FSSS particle diameter (average particle diameter measured by Fisher method) of the CoNiFeCu alloy particles obtained by the above production method is preferably 0.5 μm or more and 50 μm or less. Here, the Fisher method (Fisher Sub-Sieve Sizer) is a method for measuring the specific surface area of particles using the flow resistance of air, and the particle diameter of the particles is calculated. The FSSS particle diameter can be measured, for example, using Fisher Sub-Sieve Sizer Model 95 (manufactured by Fisher Scientific).

[0102] (NiFeCu alloy particles)

[0103] Using each of the particles, particles in which Ni, Fe and Cu are alloyed in a predetermined composition (NiFeCu alloy particles) are produced. As the production method of the NiFeCu alloy particles, the mechanical method, the chemical method, the atomization method and the like mentioned above can be mentioned, and the atomization method is preferably used.

[0104] The FSSS particle diameter of the NiFeCu alloy particles obtained by the above production method is preferably 0.5 μm or more and 50 μm or less. Also, the FSSS particle diameters of the above Co particles, the above Ni particles, the above Fe particles, and the above Cu particles are preferably 0.5 μm or more and 50 μm or less.

[0105] <mixing step>

[0106] The mixing step is a step of mixing each of the raw material powders prepared in the preparation step. By the mixing step, a mixed powder in which each of the raw material powders is mixed is obtained. Note that the mass ratio of the raw material powders (for example, WC particles, CoNiFeCu alloy particles, NiFeCu alloy particles, and the like) at the time of mixing is a ratio corresponding to the area ratio of the above first hard phase and the area ratio of the binder phase. The device used in the mixing step can use a publicly known device. For example, a pulverizer, a rolling ball mill, a Kalman mixer, a bead mill, and the like can be used.

[0107] The mixing time when a pulverizer is used is not particularly limited, and for example, 0.1 hours or more and 48 hours or less can be cited. From the viewpoint of uniformly mixing the raw material powders, the above mixing time is preferably set to 2 hours or more and 15 hours or less. The mixing condition when a pulverizer is used can be wet mixing or dry mixing. Also, the mixing can be performed in a solvent such as water, ethanol, acetone, isopropanol, or the like. The mixing can be performed together with a binder such as polyethylene glycol, paraffin, or the like.

[0108] After the mixing step, the mixed powder can also be granulated as needed. By granulating the mixed powder, it is easy to fill the mixed powder into a die or a mold at the time of the forming step described later. The granulation can apply a publicly known granulation method, and for example, a commercially available granulator such as a spray dryer can be used.

[0109] <forming step>

[0110] The forming step is a step of forming the mixed powder obtained in the mixing step into a predetermined shape to obtain a formed body. The forming method and the forming condition in the forming step can adopt a general method and condition, and are not particularly limited. For example, the mixed powder can be put in a Ta capsule, and a formed body can be obtained by pressing by pressure. The pressure of the pressing at this time can be set to 10 MPa or more and 16 GPa or less. As the predetermined shape, for example, a cutting tool shape (for example, the shape of an indexable cutting insert) can be cited.

[0111] <annealing step>

[0112] The sintering step is a step of sintering the compact obtained in the compacting step to obtain a sintered body. In the above sintering step, it is preferable to perform sintering after a sufficient time has passed after the appearance of the liquid phase of the binder phase. Specifically, the sintering temperature is preferably 1400°C or higher and 1600°C or lower. The sintering time is preferably 0.5 hours or longer and 2 hours or shorter.

[0113] The atmosphere at the time of sintering is not particularly limited, and an N2 gas atmosphere, an inert gas atmosphere such as Ar, or a hydrogen gas atmosphere can be cited. In addition, the degree of vacuum (pressure) at the time of sintering is preferably 0.1 kPa or higher and 10 kPa or lower.

[0114] Note that, in the sintering step, sinter HIP (sintering HIP) treatment, which can be pressurized at the time of sintering, can be performed. The HIP conditions can be cited as, for example, a temperature of 1300°C or higher and 1350°C or lower and a pressure of 5 MPa or higher and 200 MPa or lower in an N2 gas atmosphere, an inert gas atmosphere such as Ar, or the like.

[0115] The cooling rate from the maximum temperature to room temperature is preferably 2°C / minute or higher and 50°C / minute or lower. Here, "the cooling rate is 2°C / minute" means that the temperature is reduced at a rate of 2°C per minute. The atmosphere at the time of cooling is not particularly limited, and an N2 gas atmosphere or an inert gas atmosphere such as Ar can be cited. The pressure at the time of cooling is not particularly limited, and can be pressurized or depressurized. The pressure at the time of pressurization is, for example, 400 kPa or higher and 500 kPa or lower. In addition, the pressure at the time of depressurization is, for example, 100 kPa or lower, and is preferably 10 kPa or higher and 50 kPa or lower.

[0116] Cutting tool

[0117] The cemented carbide of the present embodiment has excellent wear resistance as described above, and thus can be used as a cutting tool or a base material. That is, the cutting tool of the present embodiment contains the above-described cemented carbide as a base material. In addition, the cemented carbide of the present embodiment can also be used as a wear-resistant tool and an abrasive tool, which contain the above-described cemented carbide as a base material.

[0118] The cemented carbide of the present embodiment can be widely used in cutting tools that have been known in the past, and examples thereof can include cutting tools, drill bits, end mills, indexable cutting inserts for milling, indexable cutting inserts for turning, metal saws, gear cutting tools, reamers, taps, and the like. In addition, the cemented carbide of the present embodiment can also be widely used in wear-resistant tools and abrasive tools that have been known in the past. As the wear-resistant tools, for example, dies, scribes, scribing wheels, dressers, and the like can be cited, and as the abrasive tools, for example, abrasive grinding wheels and the like can be cited.

[0119] The cemented carbide of the present embodiment can constitute the entirety of these tools. The cemented carbide described above can also constitute a part of these tools. Here, "constitute a part" means, for example, in the case of a cutting tool, a method in which the cemented carbide of the present embodiment is brazed to a predetermined position of an arbitrary base material as a cutting edge portion, and the like.

[0120] <coating film>

[0121] The cutting tool according to the present embodiment can also be provided with a coating film provided on the above-described base material. The wear-resistant tool and the grinding tool according to the present embodiment can also be provided with a coating film provided on the above-described base material. The composition of the above-described coating film can include one or more elements selected from the group consisting of a metal element of Group 4 of the periodic table, a metal element of Group 5 of the periodic table, a metal element of Group 6 of the periodic table, aluminum (Al), and silicon (Si), and a compound of one or more elements selected from the group consisting of nitrogen (N), oxygen (O), carbon (C), and boron (B). As the above-described compound, for example, TiCN, AI2O3, TiAIN, TiN, TiC, AlCrN, and the like can be included. In the present embodiment, the above-described coating film can also be a metal element. Furthermore, cubic boron nitride (cBN), diamond-like carbon, and the like are also suitable as the composition of the coating film. Such a coating film can be formed by a vapor deposition method such as a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, and the like. When the coating film is formed by the CVD method, a coating film having excellent adhesion to the base material is easily obtained. As the CVD method, for example, a thermal CVD method, and the like can be included. When the coating film is formed by the PVD method, a compressive residual stress is imparted, and thus the toughness of the cutting tool and the like is easily improved.

[0122] The coating film of the cutting tool according to the present embodiment is preferably provided on a portion of the base material that becomes a cutting edge and the vicinity thereof. The above-described coating film can also be provided on the entire surface of the base material. In addition, the coating film can be a single layer or a plurality of layers. The thickness of the coating film can be 1 μm or more and 20 μm or less, or 1.5 μm or more and 15 μm or less.

[0123] Example

[0124] Hereinafter, an example will be described in detail, but the present application is not limited thereto.

[0125] Production of Cemented Carbide

[0126] Preparation Step

[0127] Production of (CoNiFeCu Alloy Powder)

[0128] A powder of CoNiFeCu alloy (hereinafter sometimes referred to as "CoNiFeCu alloy powder") as a raw material of a bonding phase was produced by the following method. The CoNiFeCu alloy powder corresponds to the "CoNiFeCu alloy particles" described above. First, raw material powders were mixed at the mixing composition shown in Table 1, and a CoNiFeCu alloy was produced by an atomization method.

[0129]

[0130] Next, the obtained CoNiFeCu alloy was pulverized with a bead mill under the following conditions. A slurry containing the CoNiFeCu alloy obtained by the pulverization treatment was dried in a vacuum. According to the above procedure, a CoNiFeCu alloy powder having an FSSS particle diameter of 1.5 μm was obtained.

[0131] [Pulverization conditions of the bead mill]

[0132] Beads: particle diameter 1.0 mm

[0133] Dispersion medium: ethanol or acetone

[0134] Treatment time: 8 hours

[0135] (Preparation of other raw material powders)

[0136] As the raw material powders, powders having the compositions shown in Table 1 were prepared. As raw material powders used for the bonding phase other than the WC, TaC, and the above-described CoNiFeCu alloy powder in Table 1, the following powders were used, respectively. Note that Sample No. 106 used an HEA powder in which Al, Cr, Cu, Fe, Mn, Ti, and V were mixed at a molar ratio of 1:1:1:1:1:1:1 as a bonding phase (corresponding to Example 1 of Patent Document 1), and Sample No. 107 used an HEA powder in which Co, Cr, Cu, Fe, and Ni were mixed at an atomic ratio of 1:1:1:1:1 as a bonding phase (corresponding to Example 2 of Patent Document 2). The particles of each element of Samples Nos. 106 and 107 used commercially available products.

[0137] WC: FSSS particle diameter: 2.0 μm (0.7 μm for Sample No. 9, 5.0 μm for Sample No. 10)

[0138] Co: FSSS particle diameter: 1.1 μm

[0139] Ni: FSSS particle diameter: 3.3 μm

[0140] Fe: FSSS particle diameter: 3.0 μm

[0141] Cu: FSSS particle diameter: 2.8 μm

[0142] TaC: FSSS particle size: 1.8 μm

[0143] <mixing step>

[0144] The prepared raw material powders were added in the proportions described in Table 1, and mixed using a mortar, to produce a mixed powder. The mixing conditions are shown below. After mixing, the obtained slurry was dried in the atmosphere, to thereby obtain a mixed powder.

[0145] [mixing conditions of the mortar]

[0146] ball: cemented carbide, diameter 3.5 mm

[0147] dispersion medium: ethanol

[0148] rotation speed of the stirrer: 100 rpm

[0149] treatment time: 12 hours

[0150] <shaping step>

[0151] The obtained mixed powder was subjected to press molding, to thereby produce a shaped body in the shape of a model SNG432 (manufactured by Sumitomo Electric Hardmetal Corp.) (indexable cutting insert).

[0152] <annealing step>

[0153] The obtained shaped body was placed in a sintering furnace, and sintered in an Ar gas atmosphere (0.5 kPa) at the sintering temperature and sintering time described in Table 1.

[0154] After completion of sintering, cooling was performed to room temperature in an Ar gas atmosphere. At this time, cooling was performed at a rate of 20°C / min from the sintering temperature shown in Table 1 to room temperature. As described above, cemented carbides of Samples No. 1 to 15 and cemented carbides of Samples No. 101 to 107 were produced. The cemented carbides of Samples No. 1 to 15 correspond to Examples. The cemented carbides of Samples No. 101 to 107 correspond to Comparative Examples.

[0155] For the comparative examples, Test Nos. 101 and 105 are cemented carbides in which the composition of the binder phase is composed of Co alone. Test No. 102 is a cemented carbide in which TaC is added as a second hard phase to the raw material powder. Test Nos. 103 and 104 are cemented carbides in which the composition of the binder phase is composed of Co, Ni, Fe, and Cu, but the atomic concentration of each element does not satisfy the requirement of the present disclosure. Test No. 106 corresponds to Example 1 of Patent Document 1 and is a cemented carbide containing an HEA in which the composition of the binder phase is composed of Al, Cr, Cu, Fe, Mn, Ti, and V. Test No. 107 corresponds to Example 2 of Patent Document 2 and is a cemented carbide containing an HEA in which the composition of the binder phase is composed of Co, Cr, Cu, Fe, and Ni.

[0156] <Observation of Test Samples>

[0157] <Calculation of Average Particle Diameter of Tungsten Carbide Particles>

[0158] The cemented carbides of Test Nos. 1 to 15 and Test Nos. 101 to 107 produced were cut at a face of 0.1 mm or more from the edge portion to obtain a cut surface, and the cut surface was mirror finished. Then, the cut surface after mirror finishing was subjected to ion milling using an argon ion beam, and the cross section was used as a microscope observation test sample.

[0159] The mirror finished surface of the observation test sample was photographed at a magnification of 2000 times by a scanning transmission electron microscope (SEM) (manufactured by JEOL Ltd.). For each test sample, the photographing was performed at 10 fields of view for the outer side of the mirror finished surface and the center of the mirror finished surface, respectively.

[0160] In each test sample, for each 1 field of view, the particle diameter (Heywood diameter) of each of 300 or more tungsten carbide particles was found using image analysis type particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation), and the average particle diameter of the sintered tungsten carbide particles in total 10 fields of view was calculated. As a result, the average particle diameter of the sintered tungsten carbide particles was approximately equal to the average particle diameter of the WC particles used as a raw material. The results are shown in the column of "Average particle diameter of first hard phase" of Table 1. Note that, in the measurement of the particle diameter, the particles containing W and C were determined as tungsten carbide particles by performing element mapping using an energy dispersive X-ray spectroscopy (EDS) device attached to the SEM.

[0161] <Calculation of Area Ratio of First Hard Phase, Binder Phase, and Second Hard Phase>

[0162] Using image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation), binarization processing was performed according to the following conditions to obtain a binarized image. From the above binarized image, the area ratio of the first hard phase, the binding phase, and the second hard phase in the mirror-finished surface of each sample was calculated. The calculated area ratio of the second hard phase is shown in Table 1. Note that the mirror-finished surface was set to a portion 500 μm from the surface.

[0163] [Conditions for Binarization Processing]

[0164] Threshold value for lightness of first hard phase: 115

[0165] Threshold value for lightness of binding phase: 62

[0166] Threshold value for lightness of second hard phase: 88

[0167] [Composition Analysis of Binding Phase]

[0168] The binding phase on the mirror-finished surface of each sample was analyzed by ICP emission spectrometry (Inductively Coupled Plasma emission spectrometry) to determine the composition of the binding phase. As a result, it was found that the composition of the binding phase corresponded to the blending ratio of the raw material powder (Table 1).

[0169] [Area Ratio of Each Element of Co, Ni, Fe, and Cu in Binding Phase]

[0170] First, 10 electron images were obtained by taking a cross section obtained using a cross section polishing device (CP device) at a magnification of 5000 times using a SEM. The above electron images were subjected to a 2-value processing under the same conditions as in the above "<Calculation of area ratio of first hard phase, bonding phase, and second hard phase>" using an image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation), and 2-value images were obtained. The bonding phase was detected from the above 2-value images. With respect to the detected bonding phase, element mapping was performed on a plurality of regions of 12 μm x 9 μm using an energy dispersive X-ray spectroscopy (EDS) attached to the SEM. In the above element mapping, when the content ratio of any one of Co, Ni, Fe, and Cu was detected to be higher or lower than that of other regions of the bonding phase, point analysis was performed in the vicinity of the area center of the bonding phase, and the content ratio of each element was calculated when the total amount of the measured values of Co, Ni, Fe, and Cu was 100. The content ratio was compared with the content ratio of each element calculated by the above ICP emission spectroscopy measurement, and in the case where the difference between the two content ratios was 85% or less and 115% or more, the area of the bonding phase was measured using an image analysis particle size distribution software ("Mac-View" manufactured by MOUNTECH Corporation), and the area ratio in the entire cemented carbide was calculated. The result is shown in the column of "Area ratio of uneven regions in bonding phase" in Table 1.

[0171]

[0172]

[0173] Hereinafter, the following will be used Figure 1 The reaction resistance test of the cemented carbide of the present embodiment will be described. The cemented carbides 1 of Samples No. 1 to 15, Samples No. 101 to 107, and Inconel 718 (machined material 5) were cut off and processed in the same manner as in the above "<Area ratio of each element of Co, Ni, Fe, and Cu in bonding phase>". The cross section of each of the processed samples and the cross section of the machined material 5 were overlapped, and the state was maintained under a certain pressure of 10 kPa or more, and heating was performed in a vacuum at 900°C for 1 hour. The joint of the cemented carbide 1 and the machined material 5 after the heating treatment was cut off and processed in the same manner as in the above "<Area ratio of each element of Co, Ni, Fe, and Cu in bonding phase>", and the cross section perpendicular to the joint surface of the above joint was used as a microscope observation sample.

[0174] The processed surface of the observation sample produced as described above was photographed at a magnification of 1500 times by a scanning transmission electron microscope (SEM) (manufactured by JEOL Ltd.). One example of the SEM image thus photographed is shown in FIG. 6. Figure 1 As shown in FIG. 6, the surface of the joint of the cemented carbide 1 and the machined material 5 after the heating treatment was observed. As shown in FIG. 6, the surface of the joint was observed. As shown in FIG. 6, the surface of the joint of the cemented carbide 1 and the machined material 5 after the heating treatment was observed.​​Figure 1 In the SEM image, it was observed that due to the above-mentioned heat treatment, diffusion of the elements proceeded from the contact surface 2 of the cemented carbide 1 and the machined material 5 to the inside of the cemented carbide 1 in a certain range, and the contrast in the SEM image became lighter in a layer (diffusion phase 3) in the cemented carbide 1. In the field of view of the above-mentioned SEM image, the thickness T of the diffusion phase 3 was defined as the length of the line drawn perpendicularly from the point 4, which was the point farthest from the machined material 5 among the interface 6 of the general cemented carbide structure and the diffusion phase 3, to the contact surface 2, and the average value of the thickness T of the diffusion phase 3 in three or more fields of view existing at the contact surface 2 of the machined material 5 was measured. The result is shown in the column of "average thickness of diffusion phase" in Table 1. The smaller the average value of the thickness T of the diffusion phase 3, the more excellent the reaction resistance of the cemented carbide 1 with the Ni-based alloy can be evaluated.

[0175] When the cemented carbides of Test Nos. 1 to 15 (Examples) and Test Nos. 101 to 107 (Comparative Examples) were compared, it was found that the Examples tended to be more excellent in reaction resistance than the Comparative Examples. This indicates that in the cemented carbides involved in the Examples, by making the average content ratio of each of Co, Ni, Fe, and Cu with respect to the total amount of Co, Ni, Fe, and Cu in the binder phase all 10 at% or more and 30 at% or less, the reaction resistance is more excellent than that of the cemented carbide involved in the Comparative Examples. In addition, it also indicates that the cemented carbide involved in the Examples is more excellent in reaction resistance than that of the cemented carbide of Test No. 102 containing 4 mass% of TaC, by not containing a second hard phase (TaC) as a compounding component or by making the content of TaC 2 mass% or less with respect to the total amount of the cemented carbide.

[0176] <wear resistance test>

[0177] A cutting tool for a cutting test was produced by forming a hard film on the surface of each test sample using an ion plating method, which is one of the publicly known PVD methods. The hard film was a TiAlN film having a thickness of 4.8 μm. Hereinafter, the cutting tool using the cemented carbide of Test No. 1 as a base material will be referred to as "cutting tool of Test No. 1", and so on. The same applies to the test samples other than Test No. 1.

[0178] Using the cutting tools of Test Nos. 1 to 15 and Test Nos. 101 to 107 produced as described above, the cutting time (seconds) until the flank wear Vb reached 0.3 mm was measured according to the following cutting conditions. The result is shown in the column of "cutting time" in Table 1. The longer the cutting time, the more excellent the cutting tool can be evaluated in wear resistance. In addition, the machined material used in this test was a cemented carbide, which is known as a difficult-to-cut material, and it can be considered that the cutting edge portion of the cutting tool becomes high temperature at the time of cutting processing. Therefore, the longer the cutting time, the more excellent the cutting tool can also be evaluated in heat resistance.

[0179] [Conditions of abrasion resistance test]

[0180] Cutting material: Inconel 718

[0181] Cutting speed: 50 m / min

[0182] Feed rate: 0.15 mm / rev

[0183] Depth of cut: 1.5 mm

[0184] Cutting oil: Yes

[0185] When the cutting tools of Test Nos. 1 to 15 (Examples) and Test Nos. 101 to 107 (Comparative Examples) were compared, it was found that the abrasion resistance and heat resistance of the Examples tended to be superior to those of the Comparative Examples as a whole. This indicates that the cemented carbides involved in the Examples are superior in abrasion resistance and heat resistance to the cemented carbides involved in the Comparative Examples by having the average content ratio of each of Co, Ni, Fe, and Cu with respect to the total amount of Co, Ni, Fe, and Cu in the binder phase be 10 at% or more and 30 at% or less. In addition, it also indicates that the cemented carbides involved in the Examples are superior in abrasion resistance and heat resistance to the cemented carbide involved in Test No. 102 having 4 mass% of TaC by not containing a second hard phase (TaC) as a compounding component or by having the content of TaC be 2 mass% or less with respect to the total amount of the cemented carbide.

[0186] As described above, the embodiments and examples of the present application were explained, but it is initially intended that the configurations of the above-described respective embodiments and examples can be appropriately combined.

[0187] It should be considered that the embodiments and examples disclosed this time are exemplary in all respects and are not restrictive. The scope of the present application is not represented by the above-described embodiments and examples, but is represented by the claims, and is intended to include all changes within the meaning and the scope equivalent to the claims.

[0188] Explanation of symbols

[0189] 1 cemented carbide, 2 interface of cemented carbide and cutting material, 3 diffusion phase, 4 point farthest from cutting material among interface of diffusion phase and general cemented carbide structure, 5 cutting material, 6 interface of diffusion phase and general cemented carbide structure, T thickness of diffusion phase

Claims

1. A cemented carbide comprising a first hard phase and a binder phase, the first hard phase is composed of tungsten carbide particles, the binder phase is composed of cobalt, nickel, iron, and copper as constituent elements, the average content ratio of each of the constituent elements in the binder phase is all 10 atomic% or more and 30 atomic% or less, a second hard phase is not included, or the content of the second hard phase is 2 mass% or less relative to the total amount of the cemented carbide, the second hard phase is composed of a compound containing one or more metal elements selected from the group consisting of a Group 4 element, a Group 5 element, and a Group 6 element other than tungsten, and one or more elements selected from the group consisting of carbon, nitrogen, and oxygen, in any surface or any cross section of the cemented carbide, the area ratio of the first hard phase is 70% or more and 99% or less, and the area ratio of the binder phase is 1% or more and 30% or less.

2. The cemented carbide according to claim 1, wherein, in any cross section of the cemented carbide, when a region in which the proportion of the content ratio of at least one of the constituent elements is 85% or less and 115% or more relative to the average content ratio is regarded as a non-uniform region, the total area of the non-uniform regions in the binder phase is 6% or less relative to the entire area of the binder phase.

3. The cemented carbide according to claim 1 or claim 2, wherein, the content ratio of cobalt and nickel in the binder phase is 25 atomic% or more and 30 atomic% or less, the content ratio of iron and copper in the binder phase is 20 atomic% or more and 25 atomic% or less.

4. A cutting tool comprising the cemented carbide according to any one of claims 1 to 3 as a base material.

5. The cutting tool according to claim 4, further comprising a coating film provided on the base material.

Images