JP2010031308A - Cermet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cermet excellent in defect resistance and abrasion resistance, a cutting tool using the cermet, and a manufacturing method of the cermet. <P>SOLUTION: The cermet has a constitution where hard phases, which each include a cored particle 10a composed of a core part 11 essentially comprising TiCN and a peripheral part 12 surrounding the core part 11 and comprises a titanium composite compound, are bound to each other via a binder phase 20 essentially composed of an iron group metal such as Co. A W-enriched phase containing a large amount of W exists in a region near the core part, i.e. within 200 nm from a boundary 13 between the core part 11 and the peripheral part 12. The cermet is excellent in abrasion resistance due to the presence of cored particle 10a and is excellent in toughness because propagation of cracks formed near the boundary 13 can be suppressed due to the presence of the W-enriched phase near the boundary 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cermet containing cored particles in a hard phase, a method for producing the same, and a cutting tool based on the cermet. In particular, the present invention relates to a cermet capable of producing a cutting tool having excellent fracture resistance and wear resistance.

  Conventionally, cermets with titanium carbide (TiC) and titanium carbonitride (TiCN) as the main hard phase and bonded with iron group elements such as cobalt (Co) and nickel (Ni) have been used as base materials for cutting tools. . As the hard phase, those containing cored particles having a double structure in which the periphery of the TiC (N) phase (core part) is surrounded by a composite solid solution phase (peripheral part) such as (Ti, W) CN are known ( Patent Document 1 0004).

  The cermet tool based on cermet is superior in wear resistance compared to cemented carbide tools made of cemented carbide with tungsten carbide (WC) as the main hard phase. It has the advantages of being beautiful, 3. capable of high-speed cutting, 4. lightweight, 5. abundant raw materials and inexpensive.

Japanese Unexamined Patent Publication No. 2006-131975

  However, since TiC (N) is inferior in fracture toughness compared to WC, cermet tools generally have low toughness and inferior fracture resistance. Therefore, the conventional cermet tool is not suitable for cutting with high mechanical load, for example, intermittent cutting, and improvement of toughness is desired.

  Accordingly, an object of the present invention is to provide a cermet suitable for a cutting tool material that is excellent in wear resistance but also in toughness (breakage resistance). Moreover, the other object of this invention is to provide the manufacturing method of the said cermet. Furthermore, the other object of this invention is to provide the cutting tool which was excellent in both abrasion resistance and toughness using the said cermet as a base material.

  The present inventors conducted a cutting test using a cermet tool having cored particles as a main hard phase, and observed a tool in which chipping occurred, and the crack tends to be easily formed near the boundary between the core and the peripheral part. I got the knowledge that there is. Based on this knowledge, the present invention allows the cored particles to be present in the hard phase, and causes a phase that easily suppresses the progress of cracks in the vicinity of the boundary between the core portion and the peripheral portion, specifically, a phase rich in W to exist. To improve the toughness.

  The cermet of the present invention has a hard phase containing a compound of at least one element selected from Group 4, 5, 6 metals of the periodic table and at least one element of carbon (C) and nitrogen (N) as an iron group metal. This relates to a cermet that is bonded by a bonded phase containing as a main component. The hard phase includes cored particles having a core part mainly composed of titanium carbonitride (TiCN) and a peripheral part which is present around the core part and is made of a titanium composite compound. The titanium composite compound is a solid solution containing titanium (Ti), tungsten (W), and at least one element of C and N. In the peripheral portion, when the region within 200 nm from the boundary between the core portion and the peripheral portion is the core vicinity region, and the region more than 200 nm from the boundary is the outer region, It has a W-rich phase containing 1.6 times or more of the average W content (atomic%).

  The cermet of the present invention contains cored particles having TiCN as a core in the hard phase, so that it has excellent wear resistance, high toughness, and excellent fracture resistance. In particular, the cored particles in the cermet of the present invention have a large amount of W near the boundary between the core part and the peripheral part. According to this configuration, for example, the progress of cracks in the vicinity of the boundary between the core portion and the peripheral portion can be suppressed without making the hard phase particles ultrafine. Therefore, the defect | deletion by the progress of a crack can be suppressed. Therefore, the cutting tool based on the cermet of the present invention can ensure wear resistance by the presence of cored particles, and toughness can be achieved by the presence of a W-rich phase while maintaining high wear resistance. (Fracture resistance) can be further improved, and the tool life can be extended. Hereinafter, the present invention will be described in more detail.

<Cermet>
《Hard phase》
The hard phase is a compound of at least one metal element selected from Group 4,5,6 metals of the periodic table and at least one element of C and N, that is, carbide, nitride, carbonitride of the above metal element including. Typically, the hard phase is substantially constituted by the above compound. Furthermore, oxygen or metal elements in the order of ppm, which are contained in the raw materials or mixed in the manufacturing process, may be included as inevitable impurities.

<Cored particles>
In particular, the hard phase includes cored particles having a core part mainly composed of TiCN (atomic ratio occupies 95% or more of the whole core part) and a peripheral part existing around the core part. When the cored particles are contained in the hard phase in an amount of 60% or more, preferably 80% or more, the wear resistance is further improved.

  The peripheral portion is a solid solution containing Ti, W, and at least one element of C and N, that is, a carbide of Ti and W, a nitride of Ti and W, and a carbonitriding of Ti and W Consists of at least one kind. This peripheral part may further contain at least one metal selected from Group 4, 5, 6 metals (except Ti and W) of the periodic table. That is, the peripheral portion is composed of at least one of carbides of Ti, W and the above metals, nitrides of Ti, W and the above metals, carbonitrides of Ti, W and the above metals, and the above carbides. In addition, it is allowed to contain a constituent element of a binder phase such as Co and Ni in nitride and carbonitride. Specific compositions of the peripheral part include, for example, (Ti, W) CN, (Ti, W, Mo) CN, (Ti, W, Nb) CN, and (Ti, W, Mo, Ni) CN.

  A W-rich phase exists in the vicinity of the boundary between the core portion and the peripheral portion. As described above, the core portion is substantially composed of TiCN, so the content of W is very small, and the peripheral portion uses W as an essential element. Therefore, the boundary is a portion where the W content changes abruptly. When the annular region within 200 nm from the boundary in the peripheral portion is the core vicinity region, and the region outside the core vicinity region, that is, the region more than 200 nm from the boundary is the outer region, the W-rich phase is In the region in the vicinity of the part, the region contains W that is 1.6 times or more the average W content (atomic%) in the outer region. This W-rich phase may be present in a part along the periphery of the core, but if it continuously exists so as to cover the entire circumference of the core, the growth of cracks in the vicinity of the boundary described above is caused. Furthermore, it is easy to suppress. In addition, if a W-rich phase containing 1.8 times or more of the average W content in the outer region is present, the toughness is further improved.

  When the perpendicular line of a tangent line passing through an arbitrary point on the boundary between the core part and the peripheral part is taken, and the perpendicular direction is the width direction of the W-rich phase, the width L of the W-rich phase is not less than 5 nm and not more than 50 nm. And excellent in both toughness and wear resistance. If the width L of the W-rich phase is too small, the effect of suppressing the crack growth due to the presence of the W-rich phase cannot be obtained sufficiently, and if the width L of the W-rich phase is too large, the W-rich phase is too much, Abrasion tends to decrease. A more preferable width L of the W-rich phase is 10 nm or more and 30 nm or less.

  The size of the cored particle is not particularly limited, but it is preferable that the average particle size is 0.3 μm or more and 1.0 μm or less because of excellent wear resistance and toughness. The average particle size can be easily measured by analyzing the acquired image using commercially available image analysis software using SEM and EBSD. The particle diameter of the cored particles includes the peripheral part.

<< Binder Phase >>
The content of the binder phase tends to increase toughness and sinterability as the content increases, and if the content is small, the strength and wear resistance are less likely to decrease. Therefore, the content is preferably 15% by mass to 25% by mass with respect to the entire cermet. . The binder phase is mainly composed of an iron group metal such as Co and Ni (mass ratio is 65% or more of the whole binder phase, and the iron group metal element is the most in the binder phase). In particular, the iron group metal is preferably contained in an amount of 10% by mass or more based on the entire cermet. In addition, the binder phase allows inclusion (solid solution) of other elements considered to be caused by the raw material powder in addition to the iron group metal.

《Other elements and compounds》
When the cermet of the present invention contains molybdenum (Mo), the wet phase between the hard phase and the binder phase, in particular, the Ti compound and Ni can be improved, so that the constituent components of the binder phase are sufficiently around the hard phase particles. Can exist and can improve toughness. In particular, when the average content (atomic%) of Mo in the outer region of the peripheral portion is α and the average content (atomic percent) of W in the outer region is β, the content ratio α / β of Mo and W is 0.5. When <(α / β) <1.5 is satisfied, it is difficult to change the composition having the W-rich phase, the effect of suppressing the progress of cracks due to the presence of the W-rich phase, and the effect of improving wettability due to the presence of Mo The toughness improvement effect by both of these is obtained.

<Cutting tools>
The cermet of the present invention having the above-described configuration has core particles that are excellent in wear resistance and difficult to progress in cracks, and therefore are desired to be excellent in both wear resistance and fracture resistance. Can be suitably used. In particular, the cutting tool of the present invention using the cermet of the present invention hardly reacts with steel and can be suitably used for steel processing.

<Hard film>
The base material may include a hard film coated on at least a part of the surface thereof. The hard film is preferably provided at least at the blade edge and in the vicinity thereof, and may be provided over the entire surface of the substrate. The hard film may be a single layer or multiple layers, and the total thickness is preferably 1 to 20 μm. As a method for forming the hard film, either a chemical manual vapor deposition method (CVD method) such as a thermal CVD method or a physical vapor deposition method (PVD method) such as a cathode arc ion plating method can be used.

The hard film is one or more elements selected from the group consisting of metals of Group 4, 5, 6 of the periodic table, Al, Si and B, and one type selected from the group consisting of carbon, nitrogen, oxygen and boron It is preferable to have a compound film made of a compound with the above elements. Specific film quality includes TiCN, Al ₂ O ₃ , TiAlN, TiN, AlCrN and the like.

<Method for producing cermet>
The cermet is generally produced by a process of raw material preparation → grinding and mixing of raw materials → molding → sintering. The raw material includes a compound powder composed of a compound of at least one element selected from Group 4, 5, 6 metals of the periodic table and at least one element of carbon (C) and nitrogen (N), and an iron group metal. Powder is used. The method for producing the cermet of the present invention is particularly characterized by raw materials. Specifically, in the method for producing the cermet of the present invention, the compound powder and the iron group metal powder are used, and the hard phase containing the compound is bound by the binder phase mainly composed of the iron group metal. This method relates to a method for producing a cermet, and includes a step of preparing raw material powder and a step of sintering the obtained molded body after mixing and forming the raw material powder. Then, tungsten carbide (WC) powder, carbon powder, and tungsten (W) powder are used as the raw material powder.

  When particles containing W are present in the hard phase of the cermet, WC powder is usually used as a raw material. The present inventors replaced a part of this WC powder with carbon powder (e.g., carbon black) and W powder so as to cover the periphery of the core part, that is, at the boundary between the core part and the peripheral part. As a result, it was found that W is likely to precipitate along the boundary and that W is present in the vicinity of the boundary, thereby suppressing the progress of cracks in the vicinity of the boundary. Based on this finding, the production method of the present invention uses carbon powder and W powder (hereinafter referred to as combination powder) in addition to WC powder. According to the production method of the present invention, cored particles in which a W-rich phase exists so as to cover almost the entire periphery of the periphery of the core part can be obtained. Further, according to the production method of the present invention, many of the cored particles tend to have the W-rich phase.

  The combined powder is preferably added so that the total amount of the carbon powder and the W powder is 15% or more and less than 60% by mass relative to the total amount of the WC powder, the carbon powder, and the W powder. . If the combination powder is too small, the WC powder becomes relatively large, and WC particles grow and hardly exist as a W-rich phase, and if it is too much, it is difficult to generate a W-rich phase. The combination powder is preferably blended so that the elemental ratio of W and C is 1: 1 (mass ratio is 183.8: 12.01). By using a combination powder that has been subjected to such blending adjustment, the cermet of the present invention having a W-rich phase containing W that is 1.6 times or more the average content of W in the outer region in the region near the core is produced. Can do.

  General conditions can be used for the above production process: pulverization / mixing, molding, sintering and the like. For example, sintering is performed by holding at 1400 to 1550 ° C. for 0.5 to 1.5 hours in a nitrogen atmosphere. In particular, in the sintering step, when cooling the molded body that is heated while maintaining the predetermined temperature for a predetermined time, the cooling rate in the temperature range of 1000 ° C to 1400 ° C is 1.0 ° C / min to 3.0 ° C / min. It is preferable that During cooling, W can be positively precipitated by relatively slowing the cooling rate in the high temperature region of 1400 to 1000 ° C. If the cooling rate in this high-temperature region is too slow, the width of the W-rich phase becomes thick and the wear resistance tends to decrease. If it is too fast, W is difficult to precipitate, and the W-rich phase cannot be sufficiently produced. Preferably, it is 2 ° C./min or more and 3 ° C./min or less.

  The cermet of the present invention has a good balance of both wear resistance and fracture resistance (toughness). Since the cutting tool of the present invention based on the cermet of the present invention is excellent in wear resistance and fracture resistance, the tool life can be extended. The cermet production method of the present invention can produce the cermet with high productivity.

(Test Example 1)
A cutting tool including a base material composed of a TiCN-based cermet containing TiCN-containing particles as a main hard phase was prepared, and the structure and cutting performance (fracture resistance) of the cermet were investigated.

The base material was produced as follows. As raw material powders, powders of WC, W, carbon black (C), TiC, TiCN, NbC, TaC, Mo ₂ C, Ni, and Co were prepared so as to have the composition shown in Table 1. In this test, a sample in which a part of the WC powder was replaced with W powder and carbon black, a sample using only the WC powder, and a sample in which all of the WC powder was replaced with W powder and carbon black were prepared. Table 2 shows the blending ratio (mass ratio) of the total amount w _{(W + C)} of W powder and carbon black to the total amount w _total of WC powder, W powder, and carbon black. For example, when the blending ratio is 60%, if the composition is I, the total amount w _total of the three powders w _total : 20% by mass, and the total amount w _{(W + C)} of the two powders is 20% by mass × 60 % = 12% by mass. Commercially available powders were used.

  The prepared powder was pulverized and wet mixed, then dried and press-molded to obtain a green compact. The compacted body was sintered (10 Torr (about 1333 Pa), nitrogen atmosphere, 1500 ° C. × 1 hour) to obtain a sintered body. In the sintering process, when the green compact heated to the above temperature was cooled, the cooling rate in the temperature range of 140 to 1000 ° C. was set to 2.5 ° C./min.

  About each obtained sintered compact, the cross section was observed with the transmission electron microscope (10,000-30,000 times). FIG. 1 is a schematic diagram of an observed image, (A) is an overall view, (B) shows cored particles, and FIG. 2 shows a transmission electron micrograph of sample No. 4 observed at 30,000 times. . As shown in FIGS. 1 and 2, each sample has a structure in which particles 10a, 10b, and 10c of a compound constituting a hard phase are bonded by a bonding phase 20. In particular, the hard phase includes cored particles 10a having a multilayer structure having a core part 11 mainly composed of TiCN and a peripheral part 12 present around the core part 11 and made of a titanium composite compound. In the micrograph shown in FIG. 2, the background portion that appears whitish is the binder phase 20, and the particles that appear gray or blackish (dark gray) dispersed in the background are hard phase particles. The titanium composite compound appears gray, and the compound mainly composed of TiCN appears dark. A multi-layered particle having dark particles in a gray particle is a cored particle.

In the hard phase of each sample, select an arbitrary cored particle 10a, take an arbitrary point on the boundary 13 between the core part 11 and the peripheral part 12, orthogonal to the tangent line of this point, and this point is almost the center A vertical line xy (length: 450 nm) crossing the tangent line was taken so as to be located at E, and EDX analysis was performed along this vertical line xy. More specifically, arbitrary 10 locations are selected in one cross section (10,000 times), and there are 10 or more cored particles (multilayered particles) in one field of view (50 to 100 μm ² ) at each location. Check whether or not. If 10 or more cored particles cannot be observed, remeasure the measurement location. Arbitrary one cored particle is selected from each field in 10 fields (10 places) where 10 or more cored particles exist. Then, each selected cored particle is subjected to TEM-EDX analysis at 30,000 times. Line analysis is performed by taking a perpendicular line xy with the boundary between the portion that appears dark and the portion that appears gray as a temporary boundary between the core and the peripheral portion.

Fig. 3 shows the results of line analysis of sample No. 4, with the upper part being a micrograph showing the vicinity of the boundary between the core part and the peripheral part, the middle part being a line analysis graph of the entire composition, and the lower part being a line analysis graph of trace elements It is. As shown in FIG. 3, it can be seen that the dark portion has a large amount of Ti, C, N and is substantially composed of TiCN. The gray part contains a small amount of elements such as W, Nb, Ta, and Mo in addition to Ti, C, and N, and is composed of a composite carbonitride (solid solution) containing Ti, W, and other elements. I understand. In addition, a white portion is seen between the dark portion and the gray portion, and the W content changes relatively greatly in this white portion (see the lower part of FIG. 3). Specifically, there is a peak of W content near the dark core in the gray periphery, that is, near the boundary between the core and the periphery, and the W content immediately enters the core from the boundary. Decreases rapidly. The portion where W is reduced is taken as a true boundary between the core portion and the peripheral portion, and the boundary is re-established. Then, the maximum W content in the region near the core (the peak peak content, atomic%) and the average W content in the outer region (atomic%, average amount of analysis on the line) are measured. To do. Further, for each cored particle, the maximum W content W _max in the core vicinity region is determined to be several times the average W content W _{ave in} the outer region. W peak height Satoshi of W _max / W _ave the cored particles, determine the W peak height of ten cored particles, obtained further ten average value (average W peak height). The results are shown in Table 2.

  A sintered body (chip) of JIS standard shape SNGN120408 was produced as described above, and a chipping resistance test was performed using this chip. The results are shown in Table 2. For the test, a chip (with no film) as a sintered body and a coated chip (with a film) in which a TiAlN film (thickness 4 μm) was formed on the surface of the chip by an arc ion plating method were prepared. The test conditions (milling) were as follows: work material: SCM435 (3 sheets stacked), cutting speed: 174 m / min, cutting: 1.5 mm, feed: 0.3 mm / blade, Dry. The chipping resistance was evaluated by measuring the average cutting length until the chip reached the chipping.

As shown in Table 2, when the blending ratio of the total amount w _{(W + C)} of W powder and carbon black to the total amount w _total of WC powder, W powder and carbon black is 15% or more and less than 60%, the core It can be seen that a cermet having a hard phase with cored particles in which a portion (W rich phase) containing 1.6 times or more of the average W content in the peripheral portion is present in the vicinity of the portion is obtained. And when the cermet provided with the cored particle which has a W rich phase is utilized for a cutting tool, it turns out that it is excellent in fracture resistance.

  When the cored particles having the W-rich phase were further examined, the W-rich phase was present so as to cover substantially the entire circumference of the core. Further, when the cross section was further measured for the sample having the W-rich phase, substantially all the cored particles present in each visual field had the W-rich phase (the cored particles with respect to the entire hard phase). Is more than 60% by mass). Furthermore, the hard phase was composed of a compound substantially composed of elements constituting the raw material powder, and the binder phase was composed substantially of Co and Ni. Component analysis can be performed using EPMA, X-ray fluorescence, IPC-AES, etc. in addition to TEM-EDX analysis.

(Test Example 2)
A cutting tool base material made of TiCN-based cermet was prepared by changing the sintering conditions (cooling rate), and the structure and cutting performance (wear resistance) of the cermet were investigated.

  In this test, the same raw material powder (Composition I) as Sample No. 4 used in Test Example 1 was prepared, and after pulverization and wet mixing as in Test Example 1, press molding was performed to form a green compact. Was sintered under the same conditions as in Test Example 1. In particular, in this test, when the molded body heated to a predetermined temperature was cooled in the sintering process, the cooling rate in the temperature range of 1400 to 1000 ° C. was changed as shown in Table 3.

For each of the obtained sintered bodies, the cross section was observed with a transmission electron microscope in the same manner as in Test Example 1. As a result, cored particles were confirmed in all the samples. Next, in the same manner as in Test Example 1, with respect to the cored particles, a perpendicular line xy was drawn near the boundary between the core part and the peripheral part (length: 450 nm), and line analysis was performed by TEM-EDX analysis. And the width (W peak width) where the W content (atomic%) is 1.6 times or more of the average W content (atomic%) in the outer area in the area near the core of each cored particle L) was measured, and the average of 10 cored particles (average W peak width L _ave ) was determined. The results are shown in Table 3. The W peak width L is the length in the perpendicular xy direction used for the line analysis.

  In addition, except for changing the cooling rate as described above, in the same manner as in Test Example 1, a sintered body (chip) of JIS standard shape SNGN120408 was produced, and using this chip (without film), A wear resistance test was conducted. The results are shown in Table 3. The test conditions (milling) were as follows: Work material: SCM435 (Square material), Cutting speed: 200 m / min, Cutting: 2.0 mm, Feeding: 0.22 mm / tooth, Dry, Cutting length of 1 pass: 300 mm. The wear resistance was evaluated by measuring the flank wear amount (mm) for each pass and calculating the average after cutting 5 passes.

  As shown in Table 3, it is understood that when raw material powder having the same composition is used, cermets having a W-rich phase cannot be obtained when the cooling rate in the sintering step exceeds 3.0 ° C./min. Examination of sample No. 24 that does not have a W-rich phase revealed that a crack was generated near the boundary between the core and the peripheral part, and the amount of wear increased due to this defect. it is conceivable that. On the other hand, the slower the cooling rate, the thicker the W-rich phase, but the wear resistance tends to decrease. Considering the wear resistance and fracture resistance, it is considered that the width L of the W-rich phase is preferably 5 to 50 nm.

(Test Example 3)
By varying the amount of Mo ₂ C powder added, a cutting tool substrate made of TiCN-based cermet with varying Mo content in the cermet was prepared, and the structure and cutting performance (fracture resistance) of the cermet were improved. Examined.

In this test, raw material powders based on the composition of Sample No. 4 (Composition I) used in Test Example 1 and different amounts of addition of Mo ₂ C powder were prepared as shown in Table 4. The amount of increase / decrease in Mo ₂ C powder in the raw material powder was increased or decreased in WC powder. The prepared raw material powder was pulverized and wet-mixed in the same manner as in Test Example 1 and then press-molded to produce a compacted body, and sintered under the same conditions as in Test Example 1 (1400 to 1000 ° C. Cooling rate in the temperature range: 2.5 ° C / min).

For each of the obtained sintered bodies, the cross section was observed with a transmission electron microscope in the same manner as in Test Example 1. As a result, cored particles were confirmed in all the samples. Next, in the same manner as in Test Example 1, with respect to the cored particles, a perpendicular line xy was drawn near the boundary between the core part and the peripheral part (length: 450 nm), and line analysis was performed by TEM-EDX analysis. And in the region near the core of each cored particle, the location where the W content (atomic%) is 1.6 times or more of the average W content (atomic percent) in the outer region (W rich phase) When examined, the W-rich phase was confirmed in all the samples. Next, for each of the 10 cored particles selected in the same manner as in Test Example 1, the average Mo content α (atomic%) in the outer region of the peripheral part and the average W content β (atomic%) in the outer region (Both were the average of the analytical amounts on the line), the content ratio α / β of Mo and W was determined, and the average content ratio (α / β) _{ave of 10} was determined. The results are shown in Table 4.

Further, except for the points that the addition amount of Mo ₂ C powder as described above using different raw material powder, in the same manner as in Test Example 1 to prepare a sintered body of JIS standard shape SNGN120408 (the chip), the chip Using (without film), a fracture resistance test was performed. The results are shown in Table 4. The cutting conditions and fracture resistance evaluation methods are the same as in Test Example 1.

As shown in Table 4, as the amount of Mo ₂ C added is increased and the content of Mo in the cermet is increased, the content ratio α / β is increased. It can be seen that when the content ratio α / β is 0.5 or more and 1.5 or less, the chipping resistance is excellent.

  The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the composition of the raw material powder and the composition and thickness of the coating film can be appropriately changed.

  The cermet of the present invention can be suitably used as a cutting tool material. The cutting tool of the present invention can be suitably used for milling, particularly for cutting steel because it hardly reacts with steel. The method for producing the cermet of the present invention can be suitably used for producing the cermet.

2 is a schematic diagram of a cermet containing cored particles having a W-rich phase in a hard phase, (A) is an overall view, and (B) shows cored particles. FIG. It is a transmission electron micrograph of sample No. 4. It is explanatory drawing which shows the TEM-EDX analysis result of sample No. 4, the upper part is a micrograph showing the vicinity of the boundary between the core part and the peripheral part, the middle part is a line analysis graph of the whole composition, and the lower part is a line analysis of trace elements It is a graph.

Explanation of symbols

10a Core particles 10b, 10c Compound particles 11 Core 12 Peripheral 13 Boundary
20 bonded phase

Claims (9)

A hard phase containing a compound of at least one element selected from Group 4, 5, 6 metals and at least one element of carbon (C) and nitrogen (N) is mainly composed of an iron group metal. A cermet bonded by a binder phase,
The hard phase includes cored particles having a core mainly composed of titanium carbonitride (TiCN) and a peripheral part that is present around the core and is made of a titanium composite compound.
The titanium composite compound is a solid solution containing titanium (Ti), tungsten (W), and at least one element of C and N,
In the peripheral portion, when a region within 200 nm from the boundary between the core portion and the peripheral portion is a core portion vicinity region, and a region more than 200 nm from the boundary is an outer region, the core portion vicinity region is in the outer region A cermet having a W-rich phase containing 1.6 times or more of the average W content (atomic%).   2. The cermet according to claim 1, wherein the titanium composite compound further contains at least one element selected from metals of Group 4, 5, 6 (excluding Ti and W) of the periodic table.   3. The cermet according to claim 1, wherein the width L of the W-rich phase satisfies 5 nm ≦ L ≦ 50 nm. The cermet contains molybdenum (Mo),
When the average content (atomic%) of Mo in the outer region is α and the average content (atomic%) of W is β,
4. The cermet according to claim 1, wherein the content ratio α / β of Mo and W satisfies 0.5 <(α / β) <1.5.   A cutting tool comprising a base material comprising the cermet according to any one of claims 1 to 4.   6. The cutting tool according to claim 5, further comprising a hard film coated on the surface of the base material. As a raw material powder, a compound powder comprising a compound of at least one element selected from Group 4, 5, 6 metals of the periodic table and at least one element of carbon (C) and nitrogen (N), and an iron group metal powder And a cermet production method for producing a cermet in which a hard phase containing the compound is bonded by a binder phase mainly composed of the iron group metal,
Preparing a raw material powder;
After mixing and molding the raw material powder, comprising the step of sintering the obtained molded body,
A method for producing a cermet, wherein tungsten carbide (WC) powder, carbon powder, and tungsten (W) powder are used as the raw material powder.   8. The total amount of the carbon powder and the W powder is 15% or more and less than 60% by mass ratio with respect to the total amount of the WC powder, the carbon powder, and the W powder. Cermet manufacturing method.   9. In the sintering step, when cooling the heated molded body, a cooling rate in a temperature range of 1000 ° C. or more and 1400 ° C. or less is set to 1.0 ° C./min or more and 3.0 ° C./min or less. The method for producing cermet according to 1.