cBN sintered body

Abstract

The present invention is a cBN sintered compact, a binder phase of which includes a Ti–Al alloy that comprises at least one of Si, Mg, and Zn, and also includes Ti2CN, TiB2, AlN, and Al2O3. If the peak intensity of the Ti2CN appearing at a 2θ of 41.9° to 42.2° in XRD is ITi2CN and the peak intensity of the Ti–Al alloy appearing at a 2θ of 39.0° to 39.3° is ITiAl, then the peak intensity ratio ITi2CN / ITiAl is at least 2.0 and no greater than 30.0. In Auger electron spectroscopy maps for the individual elements Ti, Al, Si, Mg, and Zn, the ratio STiAlM / STiAl, which is the mean area STiAlM of sites where Ti, Al, and at least one of the elements Si, Mg, and Zn overlap to the mean area STiAl of sites where the elements Ti and Al overlap, is at least 0.05 and no greater than 0.98.

Description

[Technical Field]

[0001] The present invention relates to a cubic boron nitride sintered body (hereinafter sometimes referred to as a cBN sintered body), which is a hard composite material. This application claims priority to Japanese Patent Application No. 2021-14037, filed on January 30, 2021. The entire contents of this Japanese patent application are incorporated herein by reference. [Background technology]

[0002] WC-based cemented carbide has high hardness and excellent toughness, and is used not only for cutting tools but also for drilling tips of excavation tools, etc. Furthermore, cBN sintered compacts are less hard than diamond, but have the property of low reactivity with Fe-based and Ni-based materials, and are therefore used not only for cutting tools but also for drilling tips of excavation tools in iron ore and nickel ore mines.

[0003] Here, an excavation tool is a tool used to excavate and dig into the ground or bedrock. However, underground rocks are brittle materials with varying compositions and strengths. Therefore, unlike cutting processes that emphasize cutting and scraping performance, excavation tools must be able to withstand the impacts and vibrations required to break the rock, as well as the rotation required to efficiently remove the broken rock. Under these circumstances, proposals have been made to improve the cutting and drilling performance of cemented carbide and cBN sintered compacts.

[0004] For example, Patent Document 1 describes a cemented carbide containing an iron-based metal, WC, TiC, and TiCN for use in the cutting edges of deep drilling tools, and claims that the cemented carbide has excellent wear resistance and corrosion resistance even at high temperatures.

[0005] Furthermore, for example, Patent Document 2 describes a cBN sintered body for cutting tools or wear-resistant tools in which Ti2AlC is used as a binder phase-forming substance, and the surface of this binder phase-forming substance is activated to stimulate the reaction between the cBN and the binder phase, thereby forming a two-layer reaction layer on the surface of the cBN particles, consisting of a first layer containing Ti and boron and a second layer containing Al and boron over the entire surface of this first layer, thereby increasing the adhesion between the cBN and the binder phase and improving the strength, toughness, etc. of the sintered body.

[0006] Furthermore, for example, Patent Document 3 describes a self-sintered polycrystalline cubic boron nitride compact having a first phase of cBN particles and a ceramic binder phase containing a titanium compound, in which the first phase accounts for more than 80% by volume of the compact, and further, the compact contains a binder phase that is conductive or semi-conductive due to the use of Ti2AlC as a binder precursor, resulting in a high-cBN sintered body that has excellent workability in electrical discharge machining, and is described as being suitable for cutting cast iron and cemented carbide. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 53-89809 [Patent Document 2] Japanese Patent Application Publication No. 5-310474 [Patent Document 3] Special Publication No. 2013-537116 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances and proposals, and an object of the present invention is to provide a cBN sintered compact, which is a hard composite material that has excellent fatigue wear resistance and abrasive wear resistance, and further has resistance to damaging factors such as fractures caused by impacts and vibrations used to break rocks, even when used as a drilling tool. [Means for solving the problem]

[0009] The cBN sintered body according to the embodiment of the present invention is 1) It has cubic boron nitride particles and a binder phase, 2) The cubic boron nitride particles have an average particle size of 0.5 to 30.0 μm and a content of 65.0 to 93.0 vol%, 3 ) The binder phase is composed of Si, Mg, and Zn. 1 In addition to Ti-Al alloys with more than 100 types, Identified by XRD Ti2CN, TiB2, AlN, Al2O3 (However, Al 2 O 3 If it cannot be identified by XRD, its presence is confirmed by EPMA. Including, 4 ) The peak intensity of Ti2CN appearing at 2θ between 41.9° and 42.2° in XRD is I Ti2CN The peak intensity of the Ti-Al alloy that appears between 39.0° and 39.3° in 2θ is I TiAl When the ratio of the peak intensities is Ti2CN / I TiAl is 2.0 or more and 30.0 or less, 5 ) The average area S where Ti and Al overlap in the mapping images of Ti, Al, Si, Mg, and Zn elements obtained by Auger electron spectroscopy TiAl The average area S where Ti overlaps with Al and one or more elements of Si, Mg, and Zn TiAlM The ratio of S TiAlM / S TiAl is greater than or equal to 0.05 and less than or equal to 0.98. [Effects of the Invention]

[0010] The cBN sintered body has excellent fatigue wear resistance and abrasive wear resistance, and furthermore, when used as an excavation tool, it is resistant to damage factors such as chipping caused by impacts and vibrations used to break rocks. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram schematically showing overlapping areas of Ti and Al elements based on elemental mapping of Example Sintered Body 1 by Auger electron spectroscopy. [Figure 2]FIG. 2 is a diagram schematically showing overlapping areas of Ti, Al, and Si elements based on elemental mapping of Example Sintered Body 1 by Auger electron spectroscopy. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present inventors have focused on cBN sintered compacts as hard composite materials and have conducted extensive research to obtain cBN sintered compacts that have excellent fatigue wear resistance and abrasive wear resistance, and that are resistant to damage factors such as fractures caused by impacts and vibrations used to break rocks, even when used as drilling tools.

[0013] As a result, they discovered that when there is a specific relationship between the XRD peaks of Ti2CN and Ti-Al alloy contained in the binder phase of a cBN sintered body, and the Ti-Al alloy in the binder phase contains one or more of Si, Mg, and Zn, the cBN has excellent fatigue wear resistance and abrasive wear resistance, and furthermore, when used as a drilling tool, it has resistance to damage factors such as chipping caused by impacts and vibrations used to break rock.

[0014] Hereinafter, a cBN sintered body according to an embodiment of the present invention will be described in detail, focusing on the case where it is applied to a drilling tool. In this specification and claims, when a numerical range is expressed as "from A to B" or "A to B" (A and B are both numerical values), this is synonymous with "A or more, B or less," and the range includes the upper limit (B) and the lower limit (A). Furthermore, when a unit is stated only for the upper limit (B), the upper limit (B) and the lower limit (A) have the same unit.

[0015] 1. Cubic boron nitride (cBN) particles The average particle size of cBN particles and the content of cBN particles in the cBN sintered compact will be explained below.

[0016] (1) Average particle size The average particle size of the cBN particles used in this embodiment is not particularly limited, but is more preferably in the range of 0.5 μm or more and 30.0 μm or less.

[0017] The reason for this is that, in addition to improving fracture resistance by containing cBN particles within the sintered body, if the average particle size is 0.5 μm or more and 30.0 μm or less, when the tool is used as a drilling tool, fractures and chipping that originate from the uneven shape of the cutting edge caused by cBN particles falling off the surface of the tool are more reliably suppressed, and further, the propagation of cracks that develop from the interface between the cBN particles and the binder phase due to stress applied to the cutting edge during use, or cracks that develop as the cBN particles break, is reliably suppressed, resulting in even better fracture resistance.

[0018] Here, the average particle size of the cBN particles can be determined as follows. The cross section of the cBN sintered body is mirror-polished, and the mirror-polished surface is observed using a scanning electron microscope (hereinafter referred to as SEM) to obtain a secondary electron image. Next, the cBN grains in the obtained image are extracted using image processing, and the average grain size (described below) is calculated based on the maximum length of each grain determined by image analysis.

[0019] Here, when extracting the cBN particle portion of the image through image processing, in order to clearly distinguish between the cBN particle and the binder phase, the image is displayed in monochrome with 256 gradations, with 0 being black and 255 being white, and binarization processing is performed using the value calculated as (wv) / 2+v as the threshold value for the peak pixel value (v) of the cBN particle portion and the peak pixel value (w) of the binder phase portion.

[0020] Furthermore, it is preferable to select an area of, for example, about 0.5 μm × 0.5 μm as the region for determining the pixel value of the cBN particle portion, and to use the average value determined from at least three different locations within the same image region as the peak value of the pixel value of the cBN particle. Furthermore, it is preferable to select an area of ​​about 0.2 μm × 0.2 μm to about 0.5 μm × 0.5 μm as the region for determining the pixel value of the binder phase portion, and to use the average value determined from at least three different locations within the same image region as the peak value of the pixel value of the binder phase.

[0021] After the binarization process, processing is performed to separate areas where cBN grains are thought to be in contact with each other, for example, watershed image processing is used to separate cBN grains that are thought to be in contact with each other.

[0022] The areas corresponding to the cBN particles (black areas) in the image obtained after the binarization process described above are subjected to particle analysis, and the maximum length of each cBN particle obtained is used as the diameter of each cBN particle.To determine the maximum length, the Feret's diameter for one cBN particle is calculated, and the larger of the two lengths obtained is used as the maximum length, and this value is used as the diameter of each cBN particle.

[0023] Assuming each cBN particle is an ideal sphere with this diameter, the cumulative volume is calculated as the volume of each particle, and a graph is drawn based on this cumulative volume, with the vertical axis representing volume percentage (%) and the horizontal axis representing diameter (μm), and the diameter at which the volume percentage is 50% is taken as the average diameter of the cBN particles. This is done for three observation areas, and the average value is taken as the average diameter of the cBN particles (μm, this average diameter is called D50).

[0024] When performing this particle analysis, the length per pixel (μm) is set using a scale value known in advance from the SEM. The observation area is preferably an area in which at least 30 cBN particles are observed, i.e., an observation area of ​​approximately 15 μm × 15 μm when the average particle size of the cBN particles is approximately 3 μm.

[0025] (2)Content The content (vol %) of cBN particles in the cBN sintered body is not particularly limited, but is preferably 65.0 vol % or more and 93.0 vol % or less.

[0026] The reason for this is that if the content is less than 65.0 vol%, the amount of hard material (cBN particles) in the cBN sintered compact will be small, and when used as, for example, a drilling tool, the chipping resistance may decrease; on the other hand, if the content exceeds 93.0 vol%, voids that can become the starting points for cracks will be generated in the cBN sintered compact, and the chipping resistance may decrease.

[0027] The cBN particle content in a cBN sintered body can be determined as follows. Specifically, the cross-sectional structure of the cBN sintered body is observed using an SEM, the cBN particle portion of the obtained secondary electron image is extracted using image processing, and the area occupied by the cBN particles is calculated using image analysis. This is performed for at least three observation areas, and the average of the calculated area values ​​is taken as the cBN particle content (vol%). The observation area used for this image processing should be one in which at least 30 cBN particles are observed, i.e., if the average cBN particle size is 3 μm, then an observation area of, for example, approximately 15 μm × 15 μm is desirable.

[0028] 2. Bonded phase The binder phase of this embodiment preferably contains Ti2CN, TiB2, AlN, and Al2O3 in addition to a Ti-Al alloy containing one or more of Si, Mg, and Zn. Here, one or more of Si, Mg, and Zn refers to any one of Si, Mg, and Zn, or any two of Si, Mg, and Zn, or all three of Si, Mg, and Zn.

[0029] When the XRD peak intensities of TiCN and Ti-Al alloy contained in the binder phase are in a predetermined relationship, that is, The peak intensity of TiCN appearing at 2θ between 41.9° and 42.2° in XRD is I Ti2CN The peak intensity of the Ti-Al alloy that appears between 39.0° and 39.3° in 2θ is I TiAl Then, the peak intensity ratio, I Ti2CN / I TiAlPreferably, the ratio is 2.0 or more and 30.0 or less. When the peak intensity ratio is within this range, the resulting cBN sintered body has excellent wear resistance and abrasive wear resistance, and is highly resistant to damage factors such as chipping due to impacts and vibrations during rock excavation.

[0030] The reason is that I Ti2CN / I TiAl If the value is less than 2.0, the excess Ti-Al alloy present in the cBN sintered body will cause the cBN particles to react with this Ti-Al alloy to form coarse TiB2, and excessive AlN will be generated, which will become the starting point for fracture during rock excavation, etc. Ti2CN / I TiAl If the value is greater than 30.0, the amount of Ti-Al alloy in the cBN sintered body will decrease, which is thought to result in a decrease in the adhesive strength between the cBN particles and the binder phase and a decrease in the toughness of the cBN sintered body.

[0031] Here, the peak intensity of TiCN (I Ti2CN ) and the peak strength of Ti-Al alloy (I TiAl ) is measured by XRD using CuKα radiation, and the peak of the 111 diffraction line of cBN is set at 2θ=43.3. Using this peak position (angle) as a reference, the peak between 2θ of 41.9° and 42.2° is set as Ti2CN, and the peak between 2θ of 39.0° and 39.3° is set as Ti-Al alloy. After removing background noise, a peak search is performed to confirm each.

[0032] In addition, one or more of Si, Mg, and Zn are dispersed in the binder phase in the Ti-Al alloy. In the mapping images of Ti, Al, Si, Mg, and Zn elements obtained by Auger Electron Spectroscopy (AES), the average area S where Ti and Al overlap is TiAl The average area S where Ti overlaps with Al and one or more elements of Si, Mg, and Zn TiAlM Percentage of S TiAlM / S TiAl is preferably 0.05 to 0.98. Here, the observation area using AES is preferably, for example, about 15 μm×15 μm.

[0033] As an example of element mapping by AES, based on the observation results of Example Sintered Body 1 described later, Fig. 1 shows the overlapping areas of Ti and Al elements, and Fig. 2 shows the overlapping areas of Ti, Al, and Si elements. Comparing the two figures, it is clear that the overlapping areas in Fig. 2 are part of the overlapping areas in Fig. 1.

[0034] Here, the reason why the presence of one or more of Si, Mg, and Zn together with the Ti-Al alloy makes fatigue fracture less likely to occur is not entirely clear, but it is speculated as follows.

[0035] When TiAl3 reacts with cBN, TiAl3 decomposes to produce AlN together with TiB2. This AlN has low strength and is particularly susceptible to fracture due to the impact load when the cBN sintered compact is used as a drilling tool. However, by including one or more of Si, Mg, and Zn as constituent materials of the binder phase, the Al produced by the decomposition of TiAl3 reacts with compounds containing Si, Mg, and Zn to form Al2O3, suppressing the production of AlN. Furthermore, the Ti-Al alloy produced by the decomposition of TiAl3 contains one or more of Si, Mg, and Zn, which is thought to improve wear resistance.

[0036] And S TiAlM / S TiAl The reason why the above range is preferable for the value of is that if it is less than 0.05, AlN is produced in large amounts in the cBN sintered body, making it more susceptible to fatigue fracture, and the presence of enlarged AlN in the cBN sintered body makes it easier for cracks produced in the sintered body to propagate, reducing toughness. On the other hand, if it exceeds 0.98, the production of AlN is suppressed, but oxygen from the raw materials causes Al2O3 and TiCNO to be present in large amounts in the binder phase, and this TiCNO becomes more likely to become the starting point for fatigue fracture, reducing the toughness of the sintered body.

[0037] The above description includes the following additional features. (Appendix 1) A cBN sintered body having cubic boron nitride particles and a binder phase, 1) The cubic boron nitride particles have an average particle size of 0.5 to 30.0 μm and a content of 65.0 to 93.0 vol%, 2) The binder phase is composed of Si, Mg, and Zn. 1 In addition to Ti-Al alloys with more than 100 types, Identified by XRD Ti2CN, TiB2, AlN, Al2O3 (Al 2 O 3 If it cannot be identified by XRD, its presence is confirmed by EPMA. Including, 3) The peak intensity of Ti2CN appearing at 2θ between 41.9° and 42.2° in XRD is I Ti2CN The peak intensity of the Ti-Al alloy that appears between 39.0° and 39.3° in 2θ is I TiAl When the ratio of the peak intensities is Ti2CN / I TiAl is 2.0 or more and 30.0 or less, 4) In the mapping images of Ti, Al, Si, Mg, and Zn elements obtained by Auger electron spectroscopy, the average area S where Ti and Al elements overlap TiAl The average area S where Ti overlaps with Al and one or more elements of Si, Mg, and Zn TiAlM The ratio of S TiAlM / S TiAl is greater than or equal to 0.05 and less than or equal to 0.98, A cBN sintered body characterized by: (Appendix 2) 2. The cBN sintered body according to claim 1, wherein the cubic boron nitride particles have an average particle size of 0.5 μm or more and 30.0 μm or less. (Appendix 3) 3. The cBN sintered body according to claim 1, wherein the content of the cubic boron nitride particles is 65 vol% or more and 93.0 vol% or less. [Example]

[0038] Next, an example will be described, but the present invention is not limited to the example in which the present invention is applied to a tool intended for cutting rock.

[0039] This example was produced by the following steps (1) to (3): The raw material powder contained a small amount of unavoidable impurities.

[0040] (1) Preparation of raw powder As the hard raw material, cBN raw material was prepared so that the average particle size after sintering would be 0.5 to 35.0 μm, as shown in Table 2. As the raw material powders constituting the binder phase, Ti2AlC and Ti3AlC2 raw materials were prepared. Both the Ti2AlC and Ti3AlC2 raw materials had an average particle size of 50 μm.

[0041] Additionally, TiN powder (0.6), TiCN powder (0.6), TiC powder (0.6), TiAl powder (0.4), SiO powder (0.02), SiN powder (0.02), MgSiO powder (0.8), ZnO powder (0.8), and MgO powder (0.8) were separately prepared as binder phase forming raw material powders. The blending compositions of these raw materials are shown in Table 1. Here, the number in parentheses after each powder name is the average particle size (D50) in μm.

[0042] (2) Mixing and pre-heat treatment Of these prepared powders, the powders other than those containing Si, Mg, and Zn elements were filled into a ball mill container lined with cemented carbide together with cemented carbide balls and acetone and mixed. The mixing time was 1 hour so as not to crush the raw material powder into small pieces. Although not performed in this example, it is more preferable to use an ultrasonic agitator to break down the agglomerates of the raw material powder while mixing.

[0043] Next, this mixed raw material powder was subjected to preliminary heat treatment in a vacuum atmosphere of 1 Pa or less at the temperature shown as "heat treatment temperature after mixing" in Table 2, to evaporate adsorbed water from the powder surface.

[0044] The pre-heat treatment temperature is preferably 250 to 900°C under a vacuum atmosphere of 1 Pa or less. The reason for this is that if the temperature is below 250°C, the adsorbed water will not evaporate sufficiently, and Ti2AlC and Ti3AlC2 will react with the remaining water during the ultra-high-pressure, high-temperature sintering and decompose into TiO2 and Al2O3. On the other hand, if the temperature exceeds 900°C, Ti2AlC and Ti3AlC2 will react with oxygen during the pre-heat treatment and decompose into TiO2 and Al2O3, reducing the content of Ti2AlC and Ti3AlC2 in the binder phase and decreasing the toughness of the cBN sintered compact.

[0045] Next, the powders other than the powders containing Si, Mg, and Zn elements that had been subjected to the preliminary heat treatment and one or more of SiO2, Si3N4, MgSiO3, ZnO, and MgO powders were filled into a ball mill container lined with cemented carbide, along with cemented carbide balls and acetone, and mixed. The mixing time was 1 hour so as not to crush the raw material powder into small pieces. Although not performed in this example, it is more preferable to use an ultrasonic agitator to break down the agglomerates of the raw material powder while mixing.

[0046] (3) Molding and sintering Next, a compact was prepared from the obtained sintered body raw material powder, and then charged into an ultra-high pressure, high temperature sintering apparatus and sintered at a pressure of 5 GPa and a temperature of 1600°C, thereby producing cBN sintered bodies of the present invention (referred to as example sintered bodies) 1 to 23 shown in Table 2. The values ​​in Table 2 were measured using the methods described above. Here, the average particle size and content of cBN particles were measured using an observation area where at least 30 cBN particles were observed, and other observation areas were measured using the sizes shown as examples.

[0047] For comparison, comparative sintered bodies were prepared. The raw material powders were prepared as follows: a cBN raw material as the hard raw material, with an average particle size after sintering of 1.0 to 4.0 μm, as shown in Table 4; and raw material powders containing Ti2AlC or Ti3AlC2 as the raw material powder constituting the binder phase. The Ti2AlC and Ti3AlC2 raw materials had an average particle size (D50) of 50 μm (the other powders had the same average particle size as in the Examples). These were blended to obtain the compositions shown in Tables 1 and 3 and mixed in a ball mill under the same conditions as in the Examples. This was then pre-heat-treated at a predetermined temperature between 100°C and 1200°C in a vacuum atmosphere of 1 Pa or less (referred to as "heat treatment temperature after mixing" in Table 4). A compact was then prepared, which was then loaded into an ultra-high-pressure, high-temperature sintering apparatus and sintered at a pressure of 5 GPa and a temperature of 1600°C, producing comparative cBN sintered bodies 1 to 9 shown in Table 4 (referred to as comparative sintered bodies). The values ​​in Table 4 were determined in the same manner as in the examples.

[0048] [Table 1]

[0049] In Table 1, "-" indicates that the material is not contained, and "*" indicates that a part of the material was also used as a binder phase material for comparative examples.

[0050] [Table 2]

[0051] In Table 2, "*" indicates that the presence of Al2O3 was confirmed by an electron probe micro analyzer (EPMA).

[0052] [Table 3]

[0053] In Table 3, "-" indicates that the substance is not contained.

[0054] [Table 4]

[0055] In Table 4, "*1" indicates that no TiAl3 peak was detected by XRD, and "*2" indicates that the presence of Al2O3 was confirmed by EPMA.

[0056] Next, example tools 1 to 23 (referred to as Examples 1 to 23) and comparative example tools 1 to 9 (referred to as Comparative Examples 1 to 9) having shapes conforming to ISO standard RNGN090300 were fabricated from example sintered bodies 1 to 23 and comparative example sintered bodies 1 to 9, respectively, and these were attached to an NC lathe and subjected to the following wet cutting tests.

[0057] Cutting speed: 150m / min Depth of cut: 0.3mm Feed rate: 0.1mm / rev Material: Granite (Takine) Shape: Φ150mm x 200mmL Cutting oil: Water-soluble cutting oil (Neocool manufactured by MORESCO Corporation) The amount of wear and condition of the cutting edge were checked when the cutting length (cutting distance) was 800 m. However, the cutting edge was observed every 100 m of cutting length to measure the presence or absence of chipping and the amount of wear, and if the amount of wear exceeded 2000 μm, the cutting test was stopped at that point. The results are shown in Table 5.

[0058] [Table 5]

[0059] In Table 5, "*" indicates the condition when the cutting distance is 100 m.

[0060] As is clear from Table 5, all of the Examples exhibited little wear and no chipping, and therefore had excellent abrasive wear resistance. Furthermore, even when used as a drilling tool, they were resistant to damage factors such as breakage caused by impacts and vibrations used to break rock. In contrast, all of the Comparative Examples exhibited breakage or high wear even after only a short cutting length, and therefore had poor abrasive wear resistance and were prone to breakage, making them difficult to use as a drilling tool.

[0061] The above-disclosed embodiments are merely illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not by the above-disclosed embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

Claims

[Claim 1] A cBN sintered body having cubic boron nitride and a binder phase, 1) The cubic boron nitride particles have an average particle size of 0.5 to 30.0 μm and a content of 65.0 to 93.0 vol %, 2) The binder phase is a Ti-Al alloy containing one or more of Si, Mg, and Zn, as well as Ti identified by XRD. ２ CN, TiB ２ , AlN, Al ２ O ３ (When Al 2 O 3 cannot be identified by XRD, its presence is confirmed by EPMA), 3) Ti, which appears at 2θ of 41.9° to 42.2° in XRD ２ The CN peak intensity is I Ｔｉ２ＣＮ The peak intensity of the Ti-Al alloy appearing at 2θ between 39.0° and 39.3° is defined as I ＴｉＡｌ When the ratio of the peak intensities is Ｔｉ２ＣＮ / I ＴｉＡｌ is 2.0 or more and 30.0 or less, 4) In the mapping images of Ti, Al, Si, Mg, and Zn elements obtained by Auger electron spectroscopy, the average area S of the overlapping portions of Ti and Al elements ＴｉＡｌ The average area S where Ti and Al and one or more elements of Si, Mg, and Zn overlap ＴｉＡｌＭ The ratio of S ＴｉＡｌＭ / S ＴｉＡｌ is 0.05 or more and 0.98 or less, A cBN sintered body characterized by:

Images