Sintered bodies and cutting tools

Abstract

Provided are a sintered compact and a cutting tool having excellent wear resistance and defect resistance under high-speed processing.　A sintered compact (2) includes: first hard particles (10) having TiCN as the main component thereof; second hard particles (20) having (Ti, M) and (C, N) as the main components thereof; third hard particles (30) constituted from a core section (31) having TiCN as the main component thereof, and a peripheral section (32) which encases the core section (31) and has (Ti, M) and (C, N) as the main components thereof; and a binding phase (50) including at least one of Co and Ni. The binding phase (50) includes at least one of Re and Ru, and has a thickness of 5 nm in at least a portion of grain boundaries between adjacent third hard particles (30, 30). The third hard particles (30) have particles (33) including at least one selected from Co, Ni, Re, and Ru in the core sections (31), and dislocations (34) are present in both the core sections (31) and the peripheral sections (32).

Description

【Technical Field】 , , , , , , 【0004】 , , , , , , 【0001】 The present disclosure relates to a sintered body and a cutting tool. 【Background Art】 【0002】 Cutting tools using a cemented carbide or cermet including a hard phase mainly composed of tungsten carbide or titanium carbonitride and a binder phase mainly composed of an iron group element as a base material are known (see, for example, Patent Documents 1 and 2). In addition, cutting tools using a ceramic sintered body mainly composed of alumina as a base material are also known (see, for example, Patent Document 3). 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2016-020541 【Patent Document 2】 International Publication No. 2008 / 146856 【Patent Document 3】 Japanese Patent Application Laid-Open No. 5-117020 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 By the way, cutting tools using a cemented carbide or cermet as a base material are generally excellent in chipping resistance but are said to be poor in heat resistance and not suitable for high-speed machining. For reference, in Patent Document 1, the cutting speed Vc = 180 to 350 m / min is used. In Patent Document 2, the cutting speed Vc = 150 to 250 m / min is used. In addition, since cutting tools using a ceramic sintered body as a base material are generally inferior in chipping resistance, it is difficult to actively apply them to workpieces with high cutting resistance (for example, steel materials). On the other hand, in recent years, a technology for high-speed machining (for example, Vc = 500 m / min) of steel materials with high cutting resistance has been demanded. This disclosure is made in view of the above circumstances and aims to provide a sintered body and cutting tool that exhibit excellent wear resistance and fracture resistance under high-speed machining conditions. This disclosure can be realized in the following forms. [Means for solving the problem] 【0005】 [1] First hard particles mainly composed of TiCN, Secondary hard particles mainly composed of (Ti, M)(C, N)(M is one or more elements selected from groups 4-6 of the periodic table (excluding the element Ti), A third hard particle comprising a core mainly composed of TiCN, and a peripheral part enclosing the core mainly composed of (Ti, M)(C, N) (where M is one or more elements selected from groups 4-6 of the periodic table (excluding the element Ti), Particles containing at least one of Al, Zr, and Si, A sintered body comprising a binder phase containing at least one of Co and Ni, The aforementioned bonded phase is Furthermore, it includes at least one of Re and Ru, At least a portion of the grain boundaries between adjacent third hard particles, the thickness is 5 nm or less. At least one of the third hard particles is The core contains particles comprising at least one selected from Co, Ni, Re, and Ru, A sintered body in which at least one dislocation exists in both the core and the peripheral portion. 【0006】 [2] The sintered body according to [1], wherein the bonding phase further comprises Mo. 【0007】 [3] The particles comprising at least one of Al, Zr, and Si are sintered bodies according to [1] or [2], with AlN as the main component. 【0008】 [4] A cutting tool using a sintered body as described in any one of items [1] to [3]. 【0009】 A cutting tool as described in [5] and [4], wherein a coating layer is formed on the surface. [Effects of the Invention] 【0010】 According to this disclosure, it is possible to provide a sintered body with excellent wear resistance and fracture resistance under high-speed machining conditions. If the binding phase also contains Mo, high-temperature softening of the binding phase can be suppressed. Therefore, the sintered body becomes less susceptible to plastic deformation. Furthermore, a portion of the Mo dissolves into the second and third hard particles, improving the bonding strength between the binding phase and the hard particles, thereby further improving wear resistance and fracture resistance. When particles containing at least one of Al, Zr, and Si are primarily composed of AlN, thermal conductivity can be improved and the coefficient of thermal expansion can be reduced. As a result, wear resistance and fracture resistance can be further improved under high-speed machining conditions. By using the sintered body of this disclosure as a cutting tool, a cutting tool with excellent wear resistance and fracture resistance can be provided. When a coating layer is formed on the surface of a cutting tool, the surface can be hardened and oxidation of the substrate covered by the coating layer can be suppressed, thereby further improving the wear resistance of the cutting tool. [Brief explanation of the drawing] 【0011】 [Figure 1] This is a perspective view of an example of a sintered body (cutting tool). [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This figure shows a STEM image of a sintered body. [Figure 4] This figure schematically shows a STEM image of a sintered body. [Figure 5] This diagram explains why the propagation of cracks in sintered bodies is blocked. [Figure 6] This figure shows a STEM image of a sintered body. [Figure 7] This diagram schematically shows the grain boundaries between adjacent third-order hard particles. [Figure 8]It is a graph obtained by measuring the concentration of cobalt element at the periphery of the grain boundary between adjacent third hard particles by EDS. [Figure 9] It is a graph obtained by measuring the concentration of rhenium element at the periphery of the grain boundary between adjacent third hard particles by EDS. 【Embodiments for Carrying out the Invention】 【0012】 Hereinafter, the present disclosure will be described in detail. In this specification, for a description using "~" for a numerical range, unless otherwise specified, it includes the lower limit value and the upper limit value. For example, in the description "10~20", it includes both the lower limit value "10" and the upper limit value "20". That is, "10~20" has the same meaning as "10 or more and 20 or less". 【0013】 1. Sintered body (1) Structure of the sintered body The sintered body 2 includes first hard particles 10 mainly composed of TiCN, second hard particles 20 mainly composed of (Ti, M)(C, N) (M is one or more selected from elements belonging to Groups 4 to 6 of the periodic table (excluding Ti element)), a core part 31 mainly composed of TiCN, third hard particles 30 that enclose the core part 31 and are composed of a peripheral part 32 mainly composed of (Ti, M)(C, N) (M is one or more selected from elements belonging to Groups 4 to 6 of the periodic table (excluding Ti element)), particles 40 containing at least one of Al, Zr, and Si, and a bonding phase 50 containing at least one of Co and Ni. The bonding phase 50 further includes at least one of Re and Ru, and has a thickness of 5 nm or less at at least a part of the grain boundary between adjacent third hard particles 30. At least one of the third hard particles 30 has particles containing at least one selected from Co, Ni, Re, and Ru in the core part 31, and at least one or more dislocations 34 exist in both the core part 31 and the peripheral part 32. 【0014】 (2) First hard particles The first hard particle 10 mainly consists of TiCN (titanium carbonitride). Here, "main component" means that when the first hard particle 10 is considered as 100% by volume, TiCN accounts for 60% or more by volume. The content (volume %) of each substance in sintered body 2 can be calculated by determining the amount of each element using methods such as X-ray fluorescence analysis. (3)Second hard particles The second hard particle 20 mainly consists of (Ti, M)(C, N) (where M is one or more elements selected from groups 4-6 of the periodic table (excluding the element Ti)). Here, "main component" means that when the second hard particle 20 is considered as 100% by volume, the above Ti compound accounts for 60% or more by volume. M is preferably at least one element selected from Ta (tantalum), Nb (niobium), W (tungsten), V (vanadium), Cr (chromium), Zr (zirconium), Mo (molybdenum), and Hf (hafnium). Among these, at least one element selected from Ta (tantalum), Nb (niobium), and W (tungsten) is more preferred, and Ta and / or Nb is even more preferred. The second hard particle 20 may be of one type or multiple types. The presence of multiple types means that particles with different elements M (Ti, M) (C, N) are present together, as well as particles with the same element M but with different compositional ratios of Ti, M, C, N that constitute the particle (Ti, M) (C, N) are present together. Furthermore, from the viewpoint of reactivity with iron contained in the workpiece, the carbon composition ratio XC and the nitrogen composition ratio XN are preferably in the range of 0.10 to 0.90, more preferably in the range of 0.20 to 0.80, and even more preferably in the range of 0.30 to 0.70, as expressed in the ratio (XN / (XC+XN)). From the viewpoint of hardness, the ratio of titanium (XTi) to the composition ratio of metal element M (XM), expressed as (XTi / (XTi+XM)), is preferably in the range of 0.40 to 0.95, more preferably in the range of 0.50 to 0.95, and even more preferably in the range of 0.70 to 0.95. (4) Third hard particles The third hard particle 30 is composed of a core portion 31 and a peripheral portion 32 that encloses the core portion 31. The core 31 is mainly composed of TiCN. In other words, the core 31 is composed of the same components as the first hard particles 10. The explanation of the components of the core 31 will be omitted as it overlaps with the explanation of the components of the first hard particles 10. The peripheral region 32 is mainly composed of (Ti, M)(C, N) (where M is one or more elements selected from groups 4-6 of the periodic table (excluding the element Ti)). In other words, the peripheral region 32 is composed of the same components as the second hard particle 20. The explanation of the components of the peripheral region 32 will be omitted as it overlaps with the explanation of the components of the second hard particle 20. 【0015】 (5) Content of first hard particles, second hard particles, and third hard particles The content of each hard particle 10, 20, and 30 is not particularly limited, but the content of the third hard particle 30 is preferably 10 area% or more when the area occupied by the hard particles 10, 20, and 30 is taken as 100 area%. Furthermore, it is more preferable that the content of the third hard particle 30, which has particles containing at least one selected from Co, Ni, Re, and Ru in the core portion 31 and has at least one dislocation 34 present in both the core portion 31 and the peripheral portion 32, is 5 area% or more relative to the same 100 area%. When the content (area%) of the third hard particle 30 is within the above range, the wear resistance and fracture resistance of the tool using this sintered body 2 can be improved. The content (area %) of the third hard particle 30 can be confirmed by observing the STEM image of the sintered body 2 obtained by STEM (Scanning Transmission Electron Microscope). This observation is to be performed in a 15 μm square area on the cross-section of the sintered body 2. By measuring the area occupied by the observed first hard particle 10, second hard particle 20, and third hard particle 30, the content (area %) of the third hard particle 30 can be calculated. The content of each hard particle 10, 20, and 30 can be adjusted by changing the composition of the raw materials for the sintered body 2 and the sintering conditions. 【0016】 (6) Particles (dispersed particles) containing at least one of Al, Zr, and Si Particles 40 containing at least one of Al (aluminum), Zr (zirconium), and Si (silicon) are dispersed in the sintered body 2 and suppress the growth of first hard particles 10, second hard particles 20, third hard particles 30, etc. Hereinafter, particles 40 containing at least one of Al, Zr, and Si will also be referred to as dispersed particles 40. The dispersed particles 40 are exemplified by particles consisting of one or more of the nitrides, oxides, carbides, and oxynitrides of Al, Zr, and Si. For example, it is shown that they consist of one or more of the following: AlN particles (aluminum nitride particles), Al2O3 particles (aluminum oxide particles), AlON particles (aluminum oxynitride particles), ZrO2 particles (zirconium oxide particles), SiC particles (silicon carbide particles), and Si3N4 particles (silicon nitride particles). 【0017】 The content of the dispersed particles 40 is not particularly limited. When the total volume of the sintered body 2 is considered to be 100 volume%, the content of the dispersed particles 40 is preferably 3 to 20 volume%, and more preferably 5 to 15 volume%. If the content of the dispersed particles 40 is above the lower limit of the above range, the grain growth of the hard particles 10, 20, and 30 can be effectively suppressed. If the content of the dispersed particles 40 is below the upper limit of the above range, the structure of the sintered body 2 can be easily densified, ensuring hardness and improving wear resistance. 【0018】 (7) Bonded phase The bonding phase 50 contains at least one of Co (cobalt) and Ni (nickel). For example, the graph in Figure 8 shows the concentration of cobalt element around the bonding phase 50 between adjacent third hard particles 30, 30, measured using an EDS (Energy Dispersive X-ray Spectrometer). The horizontal axis of the graph in Figure 8 represents the positions on a straight line crossing the bonding phase 50 shown in Figure 7, from position A1 on one third hard particle 30, through position A2 on the bonding phase 50, to position A3 on the other third hard particle 30. The vertical axis of the graph in Figure 8 represents the concentration of cobalt element. From the graph, it can be seen that cobalt is distributed in the bonding phase 50 between adjacent third hard particles 30, 30. Thus, by including at least one of Co and Ni in the binding phase 50, the bonding between particles in each of the hard particles 10, 20, 30 and the dispersed particles 40 can be strengthened. As a result, the wear resistance and fracture resistance of the sintered body 2 can be improved. 【0019】 The total content of Co (cobalt) and Ni (nickel) in the binding phase 50 is preferably 40% to 90% by mass, and more preferably 50% to 70% by mass, when the total binding phase 50 is considered to be 100% by mass. This configuration further strengthens the bonding between particles. As a result, the wear resistance and fracture resistance of the sintered body 2 can be further improved. 【0020】 (8) Requirements concerning the bonded phase The bonded phase 50 contains at least one of Re (rhenium) and Ru (ruthenium). For example, the graph in Figure 9 shows the concentration of rhenium element around the bond phase 50 between adjacent third hard particles 30, 30, measured by EDS. The horizontal axis of the graph in Figure 9 represents the positions on the straight line crossing the bond phase 50 shown in Figure 7, from position A1 on one third hard particle 30, through position A2 on the bond phase 50, to position A3 on the other third hard particle 30. The vertical axis of the graph in Figure 9 represents the concentration of rhenium element. From the graph, it can be seen that rhenium is distributed in the bond phase 50 between adjacent third hard particles 30, 30. 【0021】 Re and Ru are high-melting-point metals. By including at least one of Re and Ru in the bonding phase 50, high-temperature softening of the bonding phase 50 can be suppressed. As a result, the sintered body 2 becomes less susceptible to plastic deformation. The total content of Re and Ru in the bonding phase 50 is preferably 5% to 50% by mass, and more preferably 10% to 25% by mass, when the total bonding phase 50 is considered to be 100% by mass. 【0022】 The thickness of the bonding phase 50 is 5 nm or less in at least a portion of the grain boundaries between adjacent third hard particles 30. If the thickness of the bonding phase 50 is below the above upper limit, high-temperature softening under high-speed cutting can be suppressed, making it difficult for the sintered body 2 to undergo plastic deformation. The thickness of the bonding phase 50 is usually 1 nm or more, but it may be a value closer to "0". The thickness of the binder phase 50 can be determined by observing STEM images and measuring the thickness T1 at the grain boundary between adjacent third hard particles 30 where the thickness of the binder phase 50 is minimized (see Figure 6). 【0023】 (9) Requirements concerning third hard particles At least one of the third hard particles 30 has a core portion 31 containing at least one element selected from Co, Ni, Re, and Ru (hereinafter also referred to as an internal particle 33), and at least one dislocation 34 is present in both the core portion 31 and the peripheral portion 32. In this disclosure, a dislocation 34 means a linear lattice defect due to a misalignment of crystal planes. 【0024】 The internal particles 33 contain at least one of the same components as those contained in the bonding phase 50. The internal particles 33 have a greater coefficient of thermal expansion than the core 31, which is mainly composed of TiCN. Furthermore, the core 31, which is mainly composed of TiCN, has a greater coefficient of thermal expansion than the peripheral 32, which is mainly composed of (Ti, M)(C, N) (where M is one or more elements selected from groups 4-6 of the periodic table (excluding the element Ti)). In other words, the third hard particle 30 having internal particles 33 has a structure in which the coefficient of thermal expansion of the core 31 is greater than that of the peripheral 32, and the coefficient of thermal expansion of the internal particles 33 is greater than that of the core 31. 【0025】 The dislocations 34 present in the core 31 may be located around the internal particles 33 contained in the core 31. Multiple dislocations 34 present in the core 31 may extend radially from the internal particles 33 contained in the core 31. The dislocations 34 present in the peripheral portion 32 may be located around the core portion 31. Multiple dislocations 34 present in the peripheral portion 32 may extend radially from the core portion 31. The number, location, and shape of dislocation 34 can be identified by observing the STEM images described later. 【0026】 The internal particles 33 and the dislocations 34 in the core 31 and peripheral 32 can be confirmed by observing STEM (Scanning Transmission Electron Microscope) images of the sintered body 2. This observation is performed within a 15 μm square area in the cross-section of the sintered body 2. For example, in the STEM image of the sintered body 2 shown in Figure 3, images of approximately circular internal particles 33 can be observed near the center of the image. In addition, linear images of dislocations 34 can be observed in the core 31 and peripheral 32 of this STEM image. The presence or absence of such images of internal particles 33 and dislocations 34 can be confirmed. A schematic diagram illustrating a STEM image is shown in Figure 4. 【0027】 By having internal particles 33 containing at least one selected from Co, Ni, Re, and Ru in the core portion 31, dislocations 34 can be retained in the core portion 31 and the peripheral portion 32. The dislocations 34 present in the core portion 31 and the peripheral portion 32 are thought to act like grain boundaries. As a result, the third hard particles 30 are made into a pseudo-fine state, and it is presumed that the third hard particles 30 become harder compared to the state without dislocations 34, improving wear resistance. In addition, the inclusion of internal particles 33 with a relatively large coefficient of thermal expansion within the third hard particles 30 results in residual compressive stress at the grain boundaries surrounding the third hard particles 30. In Figure 5, the compressive stress is indicated by white arrows. It is presumed that the sintered body 2 will have excellent wear resistance and fracture resistance because the crack propagation is blocked by the effect of this residual stress. In Figure 5, the direction of crack propagation is indicated by black arrows, and the blocked propagation is represented by cross marks. 【0028】 (10) Preferred requirements for sintered bodies Preferably, the sintered body 2 contains Mo (molybdenum) in the binding phase 50. Mo is a high-melting-point metal. By further including Mo in the bonding phase 50, the high-temperature softening of the bonding phase 50 can be further suppressed. As a result, the sintered body 2 becomes less susceptible to plastic deformation. In addition, a portion of the Mo dissolves into the second hard particles 20 and the third hard particles 30, improving the bonding strength between the bonding phase 50 and the second hard particles 20, and between the bonding phase 50 and the third hard particles 30, thereby further improving the wear resistance and fracture resistance of the sintered body 2. The presence of Mo in the bonding phase 50 can be confirmed by measurement using EDS. The molybdenum (Mo) content in the bonded phase 50 is preferably 10% to 30% by mass, and more preferably 15% to 25% by mass, when the total bonded phase 50 is considered to be 100% by mass. 【0029】 In the sintered body 2, it is preferable that the dispersed particles 40 are AlN particles (aluminum nitride particles). AlN particles (aluminum nitride particles) can increase the thermal conductivity and decrease the thermal expansion coefficient of the cutting tool 1 made using the sintered body 2. Therefore, by including AlN particles (aluminum nitride particles) as dispersed particles 40, better wear resistance and fracture resistance can be achieved under high-speed machining conditions, and the tool life is improved. 【0030】 2. Method for manufacturing a sintered body The method for manufacturing the sintered body 2 is not particularly limited. An example of a method for manufacturing the sintered body 2 is shown below. 【0031】 (1) Raw materials The following raw material powders are used as raw materials. ·Ti carbonitride raw material powder Raw material powders such as TaC powder (tantalum carbide powder), NbC powder (niobium carbide powder), and WC powder (tungsten carbide powder). Raw material powders such as AlN powder (aluminum nitride powder), Al2O3 powder (aluminum oxide powder), ZrO2 powder (zirconium oxide powder), SiC powder (silicon carbide powder), and Si3N4 powder (silicon nitride powder). Raw material powders such as Co powder (cobalt powder), Ni powder (nickel powder), Re powder (rhenium powder), Ru powder (ruthenium powder), Mo powder (molybdenum powder), etc. 【0032】 (2) Preparation of the powder for calcination The raw material powders are weighed to the predetermined mixing ratio. The raw material powders, spheres (e.g., Al2O3 spheres), and solvent (e.g., acetone) are placed in a container (e.g., a resin pot) and mixed and ground. The resulting slurry is dried by water bath to obtain a dried mixed powder. 【0033】 (3) Firing After press molding the dried mixed powder, a sintered body 2 is produced by atmospheric firing. Atmospheric firing is performed under an Ar or N2 atmosphere. 【0034】 Furthermore, the dislocations 34 within the third hard particles 30 can be controlled by the firing conditions (heating rate). These dislocations 34 are generated when internal particles 33, which have a larger coefficient of thermal expansion than the third hard particles 30, are incorporated into the third hard particles 30. Therefore, by increasing the mutual solid solution rate of the Ti carbonitride-based raw materials mentioned above, the same components as the binding phase 50 incorporated into the third hard particles 30 can precipitate as internal particles 33, generating dislocations 34. In this embodiment, the persistence of dislocations 34 can be controlled by adjusting the heating rate between 10°C and 20°C / min. 【0035】 In addition, the thickness of the bonding phase 50 at the grain boundaries between adjacent third hard particles 30 can be controlled by the particle sizes of the first hard particles 10, the second hard particles 20, and the third hard particles 30. Specifically, if these hard particles 10, 20, and 30 are fine, the grain boundary area increases, causing the bonding phase 50 to spread out and its thickness to be reduced. On the other hand, if these hard particles 10, 20, and 30 are coarse, the grain boundary area decreases, resulting in a thicker bonding phase 50. The particle sizes of the hard particles 10, 20, and 30 described above can be controlled by adding raw materials that form the dispersed particles 40 (for example, raw material powders such as AlN powder and Al2O3 powder) and by the firing temperature. Specifically, by firing at a relatively low firing temperature (for example, below 1800°C) and suppressing grain growth by the dispersed particles 40, the thickness of the binding phase 50 can be made 5 nm or less. 【0036】 3.Cutting tools As shown in Figures 1 and 2, the cutting tool 1 is made using the sintered body 2 described above. The shape of the cutting tool 1 is not particularly limited. 【0037】 The sintered body 2 can be shaped and its surface finished by at least one of the following processing methods: cutting, grinding, and polishing, to become a cutting tool 1. Of course, if these finishing processes are unnecessary, the sintered body 2 can be used as a cutting tool 1 as is. 【0038】 The cutting tool 1 may use a sintered body 2 as a base material, with a coating layer 7 formed on the surface of the base material. The coating layer 7 is not particularly limited, but preferably consists of at least one compound selected from titanium, zirconium, chromium, and aluminum carbides, nitrides, oxides, carbonitrides, carbonoxides, oxynitrides, and carbonitrides. When the coating layer 7 is formed, the surface hardness of the cutting tool 1 increases, and oxidation of the base material covered by the coating layer 7 is suppressed, thereby improving the wear resistance of the cutting tool 1. The at least one compound selected from titanium, zirconium, chromium, and aluminum carbides, nitrides, oxides, carbonitrides, carbonoxides, oxynitrides, and carbonitrides is not particularly limited, but TiN, TiAlN, TiCrAlN, and CrAlN are preferred examples. From the viewpoint of oxidation resistance and lubricity, Cr-based compounds (e.g., TiCrAlN, CrAlN) are more preferred. The coating layer 7 may be a single layer or a laminated layer in which multiple layers of films are stacked. The thickness of the coating layer 7 is not particularly limited. From the viewpoint of wear resistance, the thickness of the coating layer 7 is preferably 0.02 μm or more and 30 μm or less. [Examples] 【0039】 The present disclosure will be further described in detail below with reference to examples. Experimental Examples 1, 3, and 7-17 are examples, while Experimental Examples 2, 4-6 are comparative examples. In the table, experimental examples are indicated using "No.". Additionally, if an asterisk (*) is used, such as "*2", it indicates that it is a comparative example. 【0040】 1. Experimental Examples 1-17 Each of the sintered bodies in Experimental Examples 1 to 17 was prepared, and these sintered bodies were then processed to create each of the cutting tools in Experimental Examples 1 to 17. 【0041】 (1) Raw material powder The following raw material powders were used. TiCN powder: average particle size 1.5μm or less TiN powder: average particle size 1.5μm or less TaC powder: average particle size 1.5μm or less NbC powder: average particle size 1.5μm or less WC powder: Average particle size 1.5μm or less Al2O3 powder: Average particle size 0.7μm or less AlN powder: average particle size 0.7μm or less ZrO2 powder: average particle size 0.7μm or less SiC powder: average particle size 0.7μm or less Si3N4 powder: average particle size 0.7μm or less Co powder: Average particle size 5.0μm or less Ni powder: Average particle size 5.0μm or less Re powder: Average particle size 5.0μm or less Ru powder: Average particle size 5.0μm or less Mo powder: Average particle size 5.0μm or less 【0042】 (2) Fabrication of sintered bodies (Experimental Examples 1-17) A mixed powder was prepared using the raw material powder, and acetone was added to the mixed powder and ground and mixed for 72 hours. After grinding and mixing, the obtained slurry was dried in a water bath to remove the acetone and prepare a dried mixed powder. Using the obtained dried mixed powder, a sintered body was produced by press molding followed by atmospheric firing. The atmospheric firing conditions were a firing temperature of 1600°C to 1750°C, a heating rate of 10°C / min to 20°C / min, and an Ar or N2 atmosphere. For materials that were difficult to densify, HIP treatment was performed as appropriate. The HIP treatment conditions were 1500°C to 1700°C, 150 MPa, and an Ar atmosphere. The composition (vol%), firing temperature, and heating rate for each experimental example are shown in Table 1. Dislocations within the third hard particle were controlled by the heating rate. Specifically, by increasing the rate of mutual solid solution of the Ti carbonitride-based raw materials, the binding phase components incorporated into the third hard particle precipitated as internal particles, generating dislocations. By adjusting the heating rate, a sintered body was obtained in which at least one dislocation was present in both the core and the periphery. For example, in Experimental Example 1, the heating rate was set to 10°C / min. The thickness of the bonding phase at the grain boundaries between adjacent third-order hard particles was controlled by the addition of dispersed particle raw materials and the firing temperature. Specifically, firing was performed at a relatively low firing temperature (e.g., below 1800°C) to suppress grain growth by dispersed particles, resulting in a sintered body with a bonding phase thickness of 5 nm or less. For example, in Experimental Example 1, AlN powder was added as the dispersed particle raw material, and firing was performed at a firing temperature of 1650°C. 【0043】 [Table 1] 【0044】 (3) Presence or absence of internal particles, and presence or absence of dislocations within the third hard particle The sintered body obtained as described above was examined using STEM to observe the third hard particles present in a 15 μm square area. Then, the presence or absence of internal particles and the presence or absence of dislocations within the third hard particles were confirmed using the method described in the embodiment. In Table 2, in the "Internal Particles" column, "Present" indicates that a third hard particle containing at least one element selected from Co, Ni, Re, and Ru is observed in its core, while "Absent" indicates that such a third hard particle is not observed. In Table 2, in the "Dislocations" column, "Present" indicates that a third hard particle with at least one dislocation present in both its core and periphery is observed, while "Absent" indicates that such a third hard particle is not observed. 【0045】 (4) Thickness of the bonded phase The sintered body obtained as described above was examined using STEM to observe the third hard particles present in a 15 μm square area. The thickness (nm) of the region where the thickness of the bonding phase was minimal at the grain boundaries between adjacent third hard particles was then measured. The measurement results are shown in the "Bonding Phase Thickness" column of Table 2. 【0046】 (5) Manufacturing of cutting tools The sintered bodies from Experimental Examples 1-17 were polished to the specified dimensions to produce cutting tools. 【0047】 (6) Abrasion resistance performance evaluation test for carbon steel (6.1) Test conditions Cutting tests were conducted using each cutting tool. The test conditions were as follows: • Chip shape: CNGN120408T00520 ·Work material: S45C (JIS) ·Cutting speed: 500m / min • Cutting depth: 3.0 mm Feed rate: 0.4mm / rev. • Cutting environment: Dry cutting test (6.2) Rating The following criteria were used to evaluate the lifespan, based on the cutting distance until the end of its lifespan. A cutting distance of 1 km or more was considered acceptable. A long lifespan is one indicator of superior wear resistance and fracture resistance. ·Lifespan judgment criteria The cutting distance at which "damage" or "plastic deformation" occurred was determined as the lifespan (km). Furthermore, "plastic deformation" was determined to have occurred when the deformation of the cutting edge exceeded 0.01 mm, with the flank surface as the reference plane. (7) Evaluation results The evaluation results are shown in Table 2. 【0048】 [Table 2] 【0049】 (7.1) Presence or absence of internal particles and presence or absence of dislocations within the third hard particle Experimental Examples 1-3 were compared and examined. Experimental Example 2, which lacked internal particles and dislocations within the third hard particle, had a lifetime of 0.5 km and was deemed unsatisfactory. Experimental Example 1, which had internal particles and dislocations within the third hard particle, had a lifetime of 3.0 km and was deemed satisfactory. Experimental Example 3, which had internal particles and dislocations within the third hard particle, had a lifetime of 2.2 km and was deemed satisfactory. In other words, Experimental Example 2, which did not meet the requirements for the third hard particle, showed poor fracture resistance, while Experimental Examples 1 and 3, which did meet the requirements for the third hard particle, showed improved fracture resistance. (7.2) Regarding the thickness of the bonding phase Experimental examples 1, 3, and 4 were compared. Experimental example 4, with a binder phase thickness of 8 nm (greater than 5 nm), had a lifetime of 0.8 km and was deemed unsatisfactory. Experimental example 1, with a binder phase thickness of 2 nm (less than or equal to 5 nm), had a lifetime of 3.0 km and was deemed satisfactory. Experimental example 3, with a binder phase thickness of 5 nm (less than or equal to 5 nm), had a lifetime of 2.2 km and was deemed satisfactory. Experimental example 4 showed inferior resistance to plastic deformation, while experimental examples 1 and 3 showed improved resistance to plastic deformation. (7.3) Regarding the formulation of Re or Ru raw materials Experimental examples 1, 3, and 5 were compared. Experimental example 5, which did not contain Re or Ru raw materials, had a lifespan of 0.3 km and was unsatisfactory. Experimental example 1, which contained Re raw materials, had a lifespan of 3.0 km and was satisfactory. Experimental example 3, which contained Re raw materials, had a lifespan of 2.2 km and was satisfactory. Experimental example 5 showed poor resistance to plastic deformation, while experimental examples 1 and 3 showed improved resistance to plastic deformation. It is presumed that the plastic deformation resistance of experimental example 5 decreased due to a decrease in the heat resistance of the binder phase. (7.4) Regarding the presence or absence of dispersed particles Experimental examples 1, 3, and 6 were compared. Experimental example 6, which did not contain dispersed particles, had a lifetime of 0.4 km and was unsuccessful. Experimental example 1, which contained dispersed particles, had a lifetime of 3.0 km and was successful. Experimental example 3, which also contained dispersed particles, had a lifetime of 2.2 km and was successful. Experimental example 6 had poor fracture resistance, while experimental examples 1 and 3 showed improved fracture resistance. Furthermore, it was found that experimental example 6 had worse fracture resistance than experimental example 4, which had a similar thickness of binder phase. From this, it is inferred that the lifetime of experimental example 6 was shortened due to a decrease in fracture resistance associated with the coarsening of the first to third hard particles. (7.5) Composition of the second and third hard particles From the test results of Experimental Examples 7 and 8, it can be seen that elements belonging to groups 4-6 of the periodic table other than Ta (excluding the element Ti) may be used as the carbonitride components of the second and third hard particles. (7.6) Regarding the components of the conjugate phase The test results from Experimental Examples 9 and 10 show that Ru and Ni can be used as components of the bonded phase. The test results of Experimental Example 11 show that the bond phase component does not necessarily need to contain Mo. However, when comparing Experimental Example 11 (without Mo) with Experimental Example 1 (with Mo), Experimental Example 1 showed superior fracture resistance. Therefore, including Mo is preferable because it improves the lifespan. It was confirmed that both AlN (Experimental Example 1) and Al2O3 (Experimental Example 17) used as dispersed particles exhibited excellent wear resistance and fracture resistance. However, when comparing Experimental Example 11, which used AlN as dispersed particles, with Experimental Example 17, which used Al2O3 as dispersed particles, Experimental Example 1 showed superior fracture resistance. Therefore, it was suggested that using AlN is particularly preferable because, in addition to improved wear resistance due to the increased thermal conductivity and improved iron reactivity of the sintered body, fracture resistance is significantly improved due to the reduction in the coefficient of thermal expansion. (7.7) Regarding the composition of dispersed particles Comparing experimental examples 11-15, it can be seen that dispersion particles other than AlN and Al2O3 are also acceptable. Specifically, ZrO2, SiC, and Si3N4 can also be used. (7.8) Regarding the amount of the binding phase component Comparing experimental examples 1, 3, 7-12 with experimental examples 16 and 17, it can be seen that tool performance remains sufficient even when the amount of the binder phase component changes. Experimental Example 16 had a total amount of 3.0 vol% of the binder phase component, while Experimental Example 17 had a total amount of 8.0 vol% of the binder phase component. This suggests that a binder phase component concentration of 3.0 vol% to 8.0 vol% is preferable for achieving a long tool life. 【0050】 In experimental examples 1, 3, 7-17, sintered bodies and cutting tools exhibited excellent wear resistance and fracture resistance under high-speed machining conditions. Such cutting tools can improve the cutting speed in steel processing and increase the efficiency of machining. 【0051】 This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of the claims of this disclosure. [Explanation of Symbols] 【0052】 1...Cutting tools 2 ... Sintered body 7...Covering layer 10...First hard particle 20…Second hard particle 30…Third hard particle 31... Core part 32… Peripheral area 33…Internal particles (particles containing at least one selected from Co, Ni, Re, and Ru) 34...Transposition 40... Dispersed particles (particles containing at least one of Al, Zr, and Si) 50…bonded phase

Claims

[Claim 1] First hard particles mainly composed of TiCN, Secondary hard particles mainly composed of (Ti, M)(C, N) (where M is one or more elements selected from groups 4-6 of the periodic table (excluding the element Ti)), A third hard particle comprising a core mainly composed of TiCN, and a peripheral part enclosing the core mainly composed of (Ti, M)(C, N) (where M is one or more elements selected from groups 4 to 6 of the periodic table (excluding the element Ti), Particles containing at least one of Al, Zr, and Si, A sintered body comprising a bonding phase containing at least one of Co and Ni, The aforementioned bonded phase is Furthermore, it includes at least one of Re and Ru, At the grain boundaries between adjacent third hard particles, the thickness of the region where the thickness of the binding phase is minimized is 5 nm or less. At least one of the third hard particles is The core portion contains particles comprising at least one selected from Co, Ni, Re, and Ru, A sintered body in which at least one dislocation exists in both the core and the peripheral portion. [Claim 2] The sintered body according to claim 1, wherein the bonding phase further comprises Mo. [Claim 3] The sintered body according to claim 1 or 2, wherein the particles containing at least one of Al, Zr, and Si are mainly composed of AlN. [Claim 4] A cutting tool using a sintered body according to any one of claims 1 to 3. [Claim 5] A cutting tool according to claim 4, wherein a coating layer is formed on the surface of the cutting tool.

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