JP6510088B2 - Permanent magnet and motor, generator and car using the same - Google Patents

Description

  Embodiments of the present invention relate to a permanent magnet and a motor, a generator, and a car using the same.

  As high-performance permanent magnets, rare earth magnets such as Sm-Co based magnets and Nd-Fe-B based magnets are known. When a permanent magnet is used for a motor of a hybrid electric vehicle (Hybrid Electric Vehicle: HEV) or an electric vehicle (Electric Vehicle: EV), heat resistance is required for the permanent magnet. As a motor for HEV and EV, a permanent magnet in which part of Nd (neodymium) of an Nd-Fe-B magnet is replaced with Dy (dysprosium) to improve heat resistance is used. Since Dy is one of the rare elements, there is a need for a permanent magnet with improved heat resistance without using Dy.

It is known that Sm-Co based magnets exhibit excellent heat resistance in a composition system not using Dy because they have a high Curie temperature, and it is expected to realize good operating characteristics at high temperatures. The Sm-Co based magnet has lower magnetization than the Nd-Fe-B based magnet, and the maximum magnetic energy product ((BH) _max ) has not been realized to a sufficient value. In order to increase the magnetization of the Sm-Co based magnet, it is effective to replace a part of Co with Fe and to increase the Fe concentration. However, in the composition region where the Fe concentration is high, the coercivity of the Sm—Co based magnet tends to decrease. Furthermore, with regard to the magnetization of the Sm--Co based magnet as well, a sufficient improvement can not be obtained simply by substituting a part of Co with Fe, and thus further improvement is required.

JP, 2010-034522, A JP 2012-069750 A

  Problem to be solved by the invention is providing the permanent magnet which improved magnetic characteristics, such as magnetization and coercive force of a Sm-Co type sintered magnet, and a motor and a generator using the same.

The permanent magnet of the embodiment is
Composition formula: R _p Fe _q M _r Cu _s Co _100-pqrs
(Wherein, R is at least one element selected from rare earth elements, M is at least one element selected from Zr, Ti and Hf, and p, q, r and s are each at atomic%, 10.7. 5 ≦ p ≦ 12.5, 24 ≦ q ≦ 40, 0.88 ≦ r ≦ 4.5, 3.5 ≦ s ≦ 10.7)
And a sintered body having a composition represented by The sintered body constituting the permanent magnet of the embodiment has a structure having crystal grains composed of a main phase containing a Th ₂ Zn ₁₇ crystal phase and crystal grain boundaries of the crystal grains. In the structure of the sintered body, the average grain size of the crystal grains is 25 μm or more. In the permanent magnet of the embodiment, when indexed to the Th ₂ Zn ₁₇ crystal phase as the TbCu ₇ crystal phase, said the TbCu ₇ crystal phase [0001] shift of the crystal orientation angle to the direction of 45 degrees or more The average distance between certain crystal grains is 120 μm or more. The coercive force of the permanent magnet is 1010 kA / m or more.

It is a SEM-reflection electron image which shows the structure | tissue of a Sm-Co type sintered magnet. It is a figure which shows typically the azimuth | direction mapping figure which measured the same part as the SEM-reflection electron image of FIG. 1 by SEM-EBSP. It is a frequency distribution figure which shows the shift | offset | difference of the crystal orientation angle | corner of the [0001] direction of the crystal grain from the magnetization easy axis of a Sm-Co type sintered magnet. It is a figure which shows typically the frequency distribution mapping figure based on frequency distribution of the shift | offset | difference of the crystal orientation angle | corner shown in FIG. It is a figure showing a permanent magnet motor of an embodiment. It is a figure showing a variable magnetic flux motor of an embodiment. It is a figure showing a permanent magnet generator of an embodiment.

Hereinafter, the permanent magnet of the embodiment will be described. The permanent magnet of this embodiment is
Composition formula: R _p Fe _q M _r Cu _s Co _100-pqrs (1)
(Wherein, R is at least one element selected from rare earth elements, M is at least one element selected from Zr, Ti and Hf, and p, q, r and s are each at atomic%, 10.7. 5 ≦ p ≦ 12.5, 24 ≦ q ≦ 40, 0.88 ≦ r ≦ 4.5, 3.5 ≦ s ≦ 10.7)
And a sintered body having a composition represented by Sintered body constituting the permanent magnet has a structure having a crystal grain and crystal grain boundaries consisting of the main phase containing Th ₂ Zn ₁₇ crystal phase.

  In the above composition formula (1), as the element R, at least one element selected from rare earth elements including yttrium (Y) is used. All of the elements R impart large magnetic anisotropy to the permanent magnet and impart high coercivity. As the element R, it is preferable to use at least one selected from samarium (Sm), cerium (Ce), neodymium (Nd) and praseodymium (Pr), and in particular, it is desirable to use Sm. By setting at least 50 atomic% of the element R to Sm, the performance of the permanent magnet, in particular, the coercivity can be reproducibly enhanced. Furthermore, it is desirable that 70 atomic% or more of the element R is Sm.

  In order to increase the coercive force of the permanent magnet, the content p of the element R is set in the range of 10.5 to 12.5 atomic%. If the content p of the element R is less than 10.5 atomic%, a large amount of α-Fe phase precipitates, and a sufficient coercive force can not be obtained. When the content p of the element R exceeds 12.5 atomic%, the decrease in saturation magnetization becomes remarkable. The content p of the element R is preferably in the range of 10.7 to 12.3 atomic percent, and more preferably in the range of 10.9 to 12.1 atomic percent.

  Iron (Fe) is an element mainly responsible for the magnetization of permanent magnets. By containing Fe in a relatively large amount, the saturation magnetization of the permanent magnet can be enhanced. However, if too much Fe is contained, the α-Fe phase precipitates and it becomes difficult to obtain a desired two-phase separation structure described later, which may lower the coercive force. Therefore, the content q of Fe is set in the range of 24 to 40 atomic percent. The content q of Fe is preferably in the range of 27 to 36 at%, more preferably in the range of 29 to 34 at%.

  As the element M, at least one element selected from titanium (Ti), zirconium (Zr), and hafnium (Hf) is used. By blending the element M, a large coercive force can be expressed at a composition with a high Fe concentration. The content r of the element M is set in the range of 0.88 to 4.5 atomic percent. By setting the content r of the element M to 0.88 at% or more, the Fe concentration can be increased. On the other hand, when the content r of the element M exceeds 4.5 atomic%, a different phase rich in the element M is generated, and both the magnetization and the coercivity decrease. The content r of the element M is preferably in the range of 1.14 to 3.58 atomic percent, and more preferably in the range of 1.49 to 2.24 atomic percent.

  The element M may be any of Ti, Zr and Hf, but preferably contains at least Zr. In particular, by setting 50 atomic% or more of the element M to Zr, the effect of enhancing the coercive force of the permanent magnet can be further improved. On the other hand, among the elements M, Hf is particularly expensive, so even when using Hf, it is preferable to reduce its amount used. The content of Hf is preferably less than 20 atomic% of the element M.

  Copper (Cu) is an element for causing a permanent magnet to exhibit high coercivity. The blending amount s of Cu is set in the range of 3.5 to 10.7 atomic%. If the blending amount s of Cu is less than 3.5 atomic%, it becomes difficult to obtain high coercivity. On the other hand, if the compounding amount s of Cu exceeds 10.7 atomic%, the decrease in magnetization becomes remarkable. The compounding amount s of Cu is preferably in the range of 3.9 to 9 atomic percent, and more preferably in the range of 4.3 to 5.8 atomic percent.

  Cobalt (Co) is an element that is responsible for the magnetization of permanent magnets and is necessary to develop high coercivity. Furthermore, when a large amount of Co is contained, the Curie temperature is increased, and the thermal stability of the permanent magnet is improved. If the content of Co is too low, these effects can not be obtained sufficiently. However, when the content of Co becomes excessive, the content ratio of Fe relatively decreases and the magnetization decreases. Therefore, the content of Co is set such that the content q of Fe satisfies the above-described range, in consideration of the respective contents of the element R, the element M, and the Cu.

  A part of Co is nickel (Ni), vanadium (V), chromium (Cr), manganese (Mn), aluminum (Al), silicon (Si), gallium (Ga), niobium (Nb), tantalum (Ta) And at least one element A selected from tungsten (W). These substitution elements A contribute to the improvement of the magnet characteristics, for example, the coercivity. However, since excessive substitution of Co by the element A may cause a decrease in magnetization, the amount of substitution by the element A is preferably 20 atomic% or less of Co.

The permanent magnet of this embodiment is a sintered magnet made of a sintered body having the composition represented by the above-described composition formula (1). The sintered magnet (sintered body) has a region including a Th ₂ Zn ₁₇ crystal phase as a main phase. The main phase of the sintered magnet is the phase having the largest area ratio in the observation image (SEM image) when the cross section or the like of the sintered body is observed with a scanning electron microscope (SEM). The main phase of the sintered magnet is a phase-separated structure formed by subjecting a TbCu ₇ type crystal phase (1-7 phase / high temperature phase) formed by solution treatment as a precursor to an aging treatment, that is, Th ₂ Zn It is preferable to have a phase separation structure of a cell phase consisting of _17- type crystal phase (2-17 phase) and a cell wall phase consisting of CaCu ₅ type crystal phase (1-5 phase) or the like. Since the domain wall energy of the cell wall phase is larger than that of the cell phase, the difference in the domain wall energy serves as a barrier to domain wall movement. That is, it is considered that the coercivity of the domain wall pinning type is expressed by the cell wall phase with large domain wall energy acting as a pinning site.

The sintered magnet of the embodiment has crystal grains consisting of a main phase including a Th ₂ Zn ₁₇ crystal phase, and is made of a polycrystalline body (sintered body) of such crystal grains. Grain boundaries exist between the crystal grains constituting the sintered body. The size (grain size) of the crystal grains constituting the sintered body is generally on the micron order, and the thickness of the grain boundaries existing between such crystal grains is also on the micron order. The size of the cell phase in the main phase is nano order (for example, about 50 to 400 nm), and the thickness of the cell wall phase surrounding such cell phase is also nano order (for example, about 2 to 30 nm). The phase separation structure by the cell phase and the cell wall phase is present in the crystal grains consisting of the main phase including the 2-17 phase.

  As described above, the sintered body constituting the permanent magnet of the embodiment has the crystal grains consisting of the main phase containing the 2-17 phase and the crystal grain boundaries which are the boundaries between these crystal grains. In the permanent magnet of the embodiment, the average crystal grain size of the crystal grains consisting of the main phase is 25 μm or more, and the volume fraction of crystal grain boundaries is 14% or less. By applying a sintered body having a structure having such crystal grains and grain boundaries, it is possible to further increase the magnetization of the permanent magnet (sintered magnet). The relationship between the structure and magnetization of the permanent magnet according to the embodiment will be described in detail below.

  That is, the Sm-Co based sintered body constituting the permanent magnet is compression molded while crystal orientation of the alloy powder finely pulverized to a few μm level in a magnetic field, and this compression molded body is maintained at a predetermined temperature It is obtained by sintering. Furthermore, in the production process of the Sm--Co based sintered magnet, it is general to carry out solution treatment which is maintained at a temperature slightly lower than the sintering temperature after the sintering and then quenched. The sintering step and the solution treatment step are often performed continuously, and a sintered body is often obtained in the sintering-solution treatment step. Since the magnetization of the sintered body is in proportion to the density of the sintered body, it is desirable to obtain a sintered body density as high as possible. In addition, the higher the degree of orientation, the higher the residual magnetization. That is, in order to obtain a high residual magnetization, it can be said that it is a general method to obtain a sintered body having a high sintered body density and a high degree of crystal orientation while increasing the iron concentration of the raw material composition ratio. However, if the iron concentration is excessively increased, the coercivity is lowered. Furthermore, there is a limit to the improvement of the sintered body density and the degree of crystal orientation, and it is desirable to create a new method of improving the magnetization.

  The characteristics of the Sm--Co based sintered magnet largely depend on the above-described sintering-solution treatment process. For example, when the sintering temperature is too low, pores are generated, and a sufficient sintered body density can not be obtained. If sufficient sintered body density can not be obtained, high magnetization can not be obtained as described above. In addition, if the treatment temperature is too high, the element R such as Sm, which is a constituent element, evaporates to cause an extreme composition deviation. In such a case, there is a high possibility that sufficient coercivity can not be obtained. From this point of view, the inventors of the present invention conducted intensive investigations on the relationship between the sintering conditions and the sintered body structure and magnetic properties, and the magnetization is improved when the sintering-solution treatment is carried out under certain conditions. I found out.

  In the sintering process, each atom of the magnetic powder (alloy powder) diffuses and bonds, and sintering progresses while filling the voids. At this time, grain boundaries are formed while the magnetic powder is bonded. The sintered body is a polycrystal, and if the pulverized magnetic powder is in a state close to a single crystal, many single crystals are gathered. Each single crystal can be called a crystal grain, and the boundary between single crystals can be called a grain boundary. As the sintering progresses, the grains grow while being eaten, and the grain size increases. The present inventors found that the residual magnetization tends to increase as the crystal grain size of the sintered body increases. However, it has also been found that simply increasing the grain size does not increase the remanent magnetization.

  As a result of intensive investigation into the cause, it has been found that the improvement of the remanent magnetization is not due to the increase of the grain size itself but to the reduction of grain boundaries as the grain size increases. That is, even if the grain size of the sintered body is large, for example, the aspect ratio of the crystal grains is large, the crystal grains are in an intricate form, or the like, and the ratio of crystal grain boundaries in the sintered body is high. Residual magnetization is not improved. Heretofore, since the grain boundaries have a very small thickness, it has not been thought that the ratio of the grain boundaries affects the magnetization. Contrary to this point, the present inventors have found that the ratio of grain boundaries affects the magnetization, and came to complete the permanent magnet of the embodiment. Here, considering the grain boundaries, the grain boundaries are locations where the arrangement of atoms is disordered, that is, defects. Such grain boundaries are considered not to contribute to the magnetization. That is, the loss of magnetization can be reduced by reducing the ratio of grain boundaries even if it is slight.

  The ratio (volume fraction) of the grain boundaries in the sintered magnet (sintered body) can be determined by electron backscattering pattern (SEM-EBSP). The specific calculation method will be described later. The present inventors have found that when the ratio of grain boundaries in the sintered magnet (sintered body) is 14% or less, the magnetization of the sintered magnet is significantly improved. In order to reduce the ratio of grain boundaries, it is effective to grow crystal grains constituting the sintered body. From such a point, in the sintered body constituting the permanent magnet of the embodiment, the average crystal grain size of the crystal grains consisting of the main phase is 25 μm or more. If the ratio of crystal grain boundaries (volume fraction) exceeds 14% or the average crystal grain size of the crystal grains is less than 25 μm, the effect of improving the magnetization can not be sufficiently obtained in any case.

  That is, when the ratio of grain boundaries exceeds 14%, the effect of suppressing the loss of magnetization can not be effectively obtained by reducing the ratio of grain boundaries that do not contribute to the magnetization. The ratio of grain boundaries in the sintered magnet (sintered body) is preferably 12% or less, more preferably 10% or less. However, in order to maintain the shape of the sintered body and obtain practical strength and the like, a certain amount of crystal grain boundaries are required in the sintered body. From such a point, the ratio of grain boundaries in the sintered magnet (sintered body) is preferably 5% or more. In addition, when the average grain size of the crystal grains is less than 25 μm, the reduction effect of the crystal grain boundaries can not be sufficiently obtained. The average grain size of the crystal grains is more preferably 35 μm or more. However, if the average crystal grain size of the crystal grains is too large, the strength and the like of the sintered body (sintered magnet) are likely to decrease, so the average crystal grain size of the crystal grains is preferably 200 μm or less.

  As described above, in the permanent magnet of the embodiment, the crystal grains constituting the sintered body are sufficiently grown (average crystal grain size is 25 μm or more), and the ratio of crystal grain boundaries is decreased (volume fraction is 14% or less) ) To further improve the magnetization. In order to grow crystal grains and reduce the ratio of grain boundaries, it is generally effective to raise the sintering temperature. However, as described above, in the Sm—Co based sintered magnet, the element R such as Sm is evaporated by sintering at a high temperature, and control of the composition becomes difficult. From the viewpoint of composition control, the sintering temperature is desirably 1190 ° C. or less. However, at a sintering temperature of 1190 ° C. or less, the diffusion rate of atoms becomes slow, and crystal growth can not be performed sufficiently. With respect to such a point, the present inventors not only increase the sintering time but also increase the solution treatment time as conditions for suppressing excessive evaporation of Sm and the like and sufficiently causing crystal growth. I found that it was effective. Specific conditions will be described later.

Furthermore, when the degree of orientation of the crystal grains is evaluated by SEM-EBSP, the sintered body obtained by the sintering-solution heat treatment process, in which both the sintering time and the solution heat treatment time described above are extended, is evaluated. It is clear that the degree of orientation is also improved. It is considered that the improvement of the degree of orientation also contributes to the improvement of the magnetization. The degree of orientation of crystal grains is evaluated by the degree of deviation of the crystal orientation angle from the magnetization easy axis. In the permanent magnet of the embodiment, the Th ₂ Zn ₁₇ crystal phase in the main phase has a rhombohedral structure, but the magnetization easy axis thereof is a Th ₂ Zn ₁₇ crystal phase (2-17 phase) which is a hexagonal TbCu ₇ phase. When indexed as a crystalline phase (1-7 phase), it is parallel to the [0001] orientation of the 1-7 phase. Therefore, the degree of orientation of the crystal grains can be evaluated by measuring the degree of deviation of the [0001] orientation of the 1-7 phase between the crystal grains.

  The degree of orientation of crystal grains and the improvement effect of magnetization based on that largely depend on the existence of crystal grains in which the [0001] orientation of 1-7 phase is inclined 45 degrees or more, and the distance between such crystal grains. It became clear. That is, it has been found that the magnetization is further improved when the distance between crystal grains in which the [0001] orientation of the 1-7 phase is inclined 45 degrees or more is large. Specifically, when the 2-17 phase is indexed as the 1-7 phase, the average distance between crystal grains having a deviation of the crystal orientation angle of 45 degrees or more with respect to the [0001] orientation of the 1-7 phase is 120 μm. In the above case, it is possible to further improve the magnetization of the Sm—Co based sintered magnet. If the average distance between crystal grains having a crystal orientation angle deviation of 45 degrees or more is less than 120 μm, this means that the degree of orientation of the crystal grains is not sufficiently enhanced. Therefore, the effect of improving the magnetization based on the improvement of the degree of orientation of the crystal grains can not be effectively obtained. It is more preferable that the average distance between crystal grains having a crystal orientation angle deviation of 45 degrees or more is 180 μm or more.

  The measurement method of the average grain size of the crystal grain mentioned above, the ratio of the grain boundary, and the degree of orientation of the crystal grain will be described in detail below. In general, grain boundaries can be observed with an optical microscope or a scanning microscope (SEM). However, here, the average grain size (average grain size) of the crystal grains constituting the sintered body (sintered magnet), the ratio of crystal grain boundaries, and the degree of orientation of the crystal grains are measured and evaluated by SEM-EBSP. The reason is that when grain boundaries are observed by a secondary electron image or a backscattered electron image of SEM, the grain boundaries generally appear in a linear shape. FIG. 1 shows an example of an SEM-reflected electron image of a Sm--Co based sintered magnet. As shown in FIG. 1, the image may appear to have no grain boundaries. That is, in the secondary electron image and the backscattered electron image of the SEM, the ratio of grain boundaries may be estimated to be very small at first glance.

  In order to recognize the grain boundaries, first, the misorientation (standard misorientation) to be recognized is designated. Misorientation is specified by an angle. Then, if the misorientation between adjacent pixels (measurement points) is larger than a specified reference, it can be recognized that there is a grain boundary. For example, when the misorientation from the (0001) plane of the 1-7 phase is specified as 5 degrees or more, it is possible to recognize a portion with disordered crystal orientation (orientation difference is 5 ° C. or more) as a grain boundary. The azimuth | direction mapping figure which measured by SEM-EBSP the same part as the SEM-reflection electron image of FIG. 1 in FIG. 2 is shown typically. Although the azimuth mapping map is displayed in color, it is shown here as a gray scale image for convenience. It can be seen that grain boundaries that are difficult to observe in the SEM-reflected electron image (FIG. 1) have a certain area in the orientation mapping diagram (FIG. 2) of the SEM-EBSP. That is, it is understood that crystal defects which do not contribute to the magnetization exist at the boundaries of crystal grains. The present inventors have found a method for improving the magnetization by focusing on the ratio of grain boundaries which are crystal defects as described above and examining the correlation with the magnetic characteristics.

  The structure observation by SEM and the measurement by SEM-EBSP are performed on the inside of the sintered body. The measurement inside the sintered body is as follows. That is, in the central part of the longest side in the plane having the largest area, measurement is made on the surface part and the inside of the cross section perpendicular to the side (perpendicular to the tangent of the central part in the case of a curve). The measurement points are the reference line 1 drawn inward to the end perpendicularly to the side starting from the position of 1/2 of each side in the above-mentioned cross section, and the center of each corner as a start point A reference line 2 drawn inward toward the end at 1/2 of the internal angle is provided, and a position of 1% of the length of the reference line from the start point of these reference lines 1 and 2 is a surface portion Define the position of% as internal. When a corner has a curvature by chamfering etc., let the intersection which extended the adjacent side be the edge part (center of a corner) of a side. In this case, the measurement point is not from the intersection but from the part in contact with the reference line.

  By setting the measurement points as above, for example, when the cross section is a quadrangle, the reference lines 1 and 2 become 4 in total each with 4 lines, and the measurement points are 8 points each on the surface and inside. Become. In this embodiment, it is preferable that all eight portions in the surface portion and in the inside satisfy the above-mentioned definitions of the crystal grain diameter and the grain boundary ratio, but at least four portions in each of the surface portion and the inside It suffices to meet the requirements. In this case, the relationship between the surface portion and the inside of one reference line is not defined. After observing and smoothing the observation surface inside the sintered body defined in this way, observation is performed.

  Below, the concrete procedure which calculates | requires the average particle area and average particle diameter (average crystal grain diameter) of the crystal grain which exist in a measurement area is shown. The observation is performed on a cross-section perpendicular to the magnetization easy axis ([1 1 1] orientation of the 1-7 crystal phase / c axis direction) of the 2-17 phase which is the cell phase with respect to the sintered body subjected to the magnetic field orientation. This cross section is defined as an ND surface. In the sample oriented ideally, the (0001) planes of all the crystal grains are in parallel with the ND plane (that is, the [0001] orientation is perpendicular to the ND plane).

  First, as pretreatment of the observation surface of the sample, the sample is embedded in an epoxy resin, mechanically polished and buffed, and then water washing and water sprinkling by air blow are performed. The sample after water sprinkling is surface-treated with a dry etching apparatus. Next, the sample surface is observed with a scanning electron microscope S-4300SE (manufactured by Hitachi High-Technologies Corporation) to which EBSD system-Digiview (manufactured by TSL Corporation) is attached. The observation conditions are an acceleration voltage of 30 kV and a measurement area of 500 μm × 500 μm. It is desirable that the observation magnification be based on 150 times. However, when the number of crystal grains is less than 15 in the measurement area (500 μm × 500 μm), it is desirable to set the observation magnification to 250 times and the measurement area to 800 μm × 800 μm. From the observation results, the average grain area and the average grain diameter of the crystal grains present in the measurement area range are determined under the following conditions.

  At a step size of 2 μm, the orientation of all pixels in the measurement area range is measured, and a boundary where the misorientation between adjacent pixels is 5 ° or more is regarded as a grain boundary. However, crystal grains whose measurement points included in the same crystal grain are less than 5 points and crystal grains reaching the end of the measurement area range are not regarded as crystal grains. The grain area is the area in the same crystal grain surrounded by grain boundaries, and the average grain area is the average value of the areas of the crystal grains present in the measurement area range. The grain size is the diameter of a perfect circle having the same area as the area in the same crystal grain, and the average grain size is the average value of the grain sizes of the crystal grains present in the measurement area range.

  The ratio of grain boundaries in any region within the observation area is determined under the following conditions. First, with the step size of 2 μm, the orientations of all the pixels in the measurement area range are measured, and boundaries where the orientation difference between adjacent pixels is 5 ° or more are regarded as grain boundaries. Note that crystal grains are those in which two or more pixels are connected. Next, in an arbitrary region, the ratio of crystal grain boundaries is calculated by image analysis using the contrast difference with the inside of the crystal grain. The pixels in which the contrast difference between the inside of the crystal grain and the crystal grain boundary can not be distinguished may be corrected beforehand in software.

  Furthermore, the degree of orientation of crystal grains can be evaluated by evaluating the deviation of the crystal orientation angle obtained when the measurement is performed by the above-described SEM-EBSP. First, in the orientation mapping diagram of SEM-EBSP in which the above-mentioned ND plane is the observation plane, a large number of crystal grains in which the (0001) plane is parallel to the ND plane (that is, the [0001] orientation is perpendicular to the ND plane) It should occupy Next, the deviation of the [0001] orientation of the 1-7 phase from the magnetization easy axis direction (ND direction) is evaluated. FIG. 3 shows an example of a graph in which the deviation of the crystal orientation angle of the [0001] orientation of the crystal grain from the easy magnetization axis direction (ND direction) is represented as a frequency distribution. In this figure, crystal grains having a crystal orientation angle deviation of 45 degrees or more are defined as non-oriented grains (non-oriented grains). When the spacing between unoriented grains is large, residual magnetization tends to be large.

  Unoriented particles can be eliminated by being corroded by surrounding particles in the process of sintering or solution treatment. However, when many unoriented grains are densely present in the initial stage of sintering, the grains around the unoriented grains are rather dragged to the unoriented grains, and the degree of orientation may be deteriorated. That is, a long distance between unoriented grains means that the degree of orientation of crystal grains is high. Specifically, when the average distance between unoriented grains (the average distance between crystal grains in which the [0001] orientation is inclined 45 degrees or more) L is 120 μm or more, improvement of residual magnetization by improvement of the degree of orientation of crystal grains The effect can be obtained more clearly. The average distance L between unoriented grains is determined as follows.

  First, the deviation of the crystal orientation angle of the [0001] orientation from the ND direction is mapped. FIG. 4 schematically shows a frequency distribution mapping chart based on a frequency distribution of deviation of crystal orientation angle shown in FIG. 3. Next, one arbitrary unoriented grain on the frequency distribution mapping chart is selected. This is referred to as unoriented particles 1. Next, unoriented grains at the shortest distance from unoriented grains 1 are searched for. The unoriented grains at this shortest distance are referred to as unoriented grains 2. Next, the distance between the non-oriented particles 1 and the non-oriented particles 2 is measured. Next, except for the non-oriented particles 1, the non-oriented particles at the shortest distance from the non-oriented particles 2 are searched for. The unoriented grains at this shortest distance are referred to as unoriented grains 3. The distance between the non-oriented particles 2 and the non-oriented particles 3 is measured. This operation is performed until the unoriented grains 15 are obtained, and the average value of the measurement distances is made the distance L1 between the unoriented grains. This operation is carried out at three different places in the field of view, and an average value of the obtained distances L1 to L3 between the non-oriented grains is defined as an average distance L between the non-oriented grains.

  The permanent magnet of this embodiment is produced, for example, as follows. First, an alloy powder containing a predetermined amount of elements is prepared. The alloy powder is prepared, for example, by casting a molten alloy melt by an arc melting method or a high frequency melting method to form an alloy ingot, and crushing the alloy ingot. Other methods of preparing the alloy powder include a strip casting method, a mechanical alloying method, a mechanical grinding method, a gas atomizing method, a reduction diffusion method and the like, and the alloy powder prepared by these methods may be used. The alloy powder thus obtained or the alloy before grinding may be subjected to heat treatment as necessary to be homogenized. Pulverization of flakes and ingots is carried out using a jet mill, ball mill or the like. The grinding is preferably carried out in an inert gas atmosphere or in an organic solvent in order to prevent the oxidation of the alloy powder.

  The average particle size of the crushed alloy powder is preferably in the range of 2 to 5 μm, and more preferably, the volume ratio of particles having a particle size in the range of 2 to 10 μm is 80% or more of the whole powder. The alloy powder having such a particle size is easy to be magnetically oriented. The grinding is preferably carried out in a jet mill. In the case of a ball mill, fine particles generated during grinding can not be removed, so even if the average particle diameter is in the range of 2 to 5 μm, many particles at the submicron level are included. The aggregation of such fine particles makes it difficult to orient the magnetic field. Furthermore, the fine particles cause an increase in the amount of oxide in the sintered body, which may lower the coercive force.

  When the iron concentration in the magnet composition is 24 atomic% or more, the alloy powder after grinding preferably has a volume fraction of particles having a particle size exceeding 10 μm of 10% or less. When the iron concentration is 24 atomic% or more, the amount of heterophases in the alloy ingot increases. Not only the amount of heterophase but also the size tends to increase, and may be 20 μm or more. When such an ingot is crushed, for example, if particles of 15 μm or more are present, these particles may become heterophase particles as they are. Such heterophase particles remain even after sintering, causing a decrease in coercive force, a decrease in magnetization, a decrease in squareness, and the like. From such a point, it is preferable to reduce the ratio of coarse particles.

  Next, the alloy powder is filled in a mold placed in an electromagnet or the like, and compression molding is performed while applying a magnetic field to produce a compression molded body in which crystal axes are oriented. By sintering the compression-molded body under appropriate conditions, a sintered body having a high density can be obtained. In order to increase the density of the sintered body, it is preferable that sintering of the compression-molded product be performed by combining baking in a vacuum atmosphere and baking in an inert gas atmosphere such as Ar gas. In this case, first, the compression molded body is heated to a predetermined temperature in a vacuum atmosphere, and then the sintering atmosphere is switched from a vacuum atmosphere to an inert gas atmosphere, and then heated to a predetermined sintering temperature for sintering. Is preferred.

  The sintering temperature is preferably in the range of 1110 to 1190 ° C. The holding time (sintering time) at the sintering temperature is preferably in the range of 6 to 20 hours. When the sintering temperature exceeds 1190 ° C., evaporation of Sm and the like tends to occur. If the sintering temperature is less than 1110 ° C., a dense sintered body can not be obtained. If the sintering temperature exceeds 1190 ° C., the Sm and the like in the alloy powder are excessively evaporated, resulting in a compositional deviation, which may result in failure to obtain good magnetic properties. As for sintering temperature, 1150 degreeC or more is more preferable, More preferably, it is 1165 degreeC or more. Moreover, as for sintering temperature, 185 degrees C or less is more preferable.

  The sintering time is preferably 6 hours or more in order to grow crystal grains and reduce the ratio of grain boundaries. If the sintering time is less than 6 hours, the crystal grains can not be sufficiently grown, and the ratio of grain boundaries tends to increase accordingly. Due to these, there is a possibility that the magnetization of the sintered magnet can not be sufficiently increased. Furthermore, density non-uniformity occurs, which also tends to reduce the magnetization. If the sintering time exceeds 20 hours, the evaporation amount of Sm or the like may increase, which may make it difficult to control the composition. The sintering time is more preferably 8 hours or more, still more preferably 10 hours or more. The sintering time is more preferably 16 hours or less, still more preferably 14 hours or less. Sintering is preferably performed in vacuum or in an inert gas atmosphere also from the viewpoint of preventing oxidation.

  Next, the obtained sintered body is subjected to a solution treatment to control the crystal structure. The solution treatment may be performed continuously with the sintering. The solution treatment is preferably carried out by holding at a temperature in the range of 1100 to 1190 ° C. for 6 to 28 hours in order to obtain a 1-7 phase which is a precursor of a phase separated structure. At temperatures below 1100 ° C. and temperatures above 1190 ° C., the proportion of the 1-7 phase in the sample after solution treatment is small, and good magnetic properties can not be obtained. The solution treatment temperature is more preferably in the range of 1120 ° C. to 1180 ° C., further preferably in the range of 1120 ° C. to 1170 ° C.

  The solution treatment time also affects grain growth, and if the time is short, the ratio of grain boundaries can not be sufficiently reduced. Furthermore, there is a possibility that the coercivity may be reduced due to the non-uniform constituent phase. For this reason, it is preferable to set the holding time according to the solution treatment temperature to 6 hours or more. However, if the holding time by the solution treatment temperature is too long, the evaporation amount such as Sm may increase and the composition control may become difficult. Therefore, the holding time by the solution treatment temperature is preferably 28 hours or less. The solution treatment time is more preferably in the range of 12 to 24 hours, further preferably in the range of 14 to 18 hours. The solution treatment is preferably performed in vacuum or in an inert gas atmosphere such as argon gas to prevent oxidation.

  As described above, in order to grow crystal grains and reduce the ratio of grain boundaries, it is preferable to extend the solution treatment time as well as to prolong the sintering time. Therefore, it is preferable to set the sintering time and the solution treatment time to 6 hours or more. In addition, it is preferable to set the total of the sintering time and the solution treatment time to 16 hours or more. That is, when the sintering time is 6 hours, the solution treatment time is preferably 10 hours or more. When the solution treatment time is 6 hours, the sintering time is preferably 10 hours or more. If the total time is less than 16 hours, the ratio of grain boundaries can not be sufficiently reduced, and the degree of orientation may not be sufficiently increased. The total time of the sintering time and the solution treatment time is more preferably 19 hours or more, still more preferably 22 hours or more.

The solution treatment step is preferably maintained at the above-mentioned temperature for a certain period of time and then quenched. This quenching is carried out to maintain the metastable 1-7 phase even at room temperature. When the sintering or solution treatment is performed for a long time, the 1-7 phase may be difficult to be stabilized. At this time, by setting the cooling rate to −170 ° C./min or more, the 1-7 phase is easily stabilized and the coercive force is easily developed. Furthermore, when the cooling rate is less than -170 ° C./min, a Ce ₂ Ni ₇ crystal phase (2-7 phase) may be generated during cooling. This phase may be a factor that reduces the magnetization and the coercivity. The 2-7 phase is often enriched with Cu, which lowers the concentration of Cu in the main phase, making it difficult for the aging treatment to cause phase separation into the cell phase and the cell wall phase.

  Next, the sintered body after the solution treatment is subjected to an aging treatment. The aging treatment is a treatment that controls the crystal structure to increase the coercivity of the magnet. The aging treatment is maintained at a temperature of 700 to 900 ° C. for 0.5 to 80 hours, and then gradually cooled to a temperature of 400 to 650 ° C. at a cooling rate of 0.2 to 2 ° C./min. Cooling is preferred. The aging treatment may be carried out by a two-step heat treatment. For example, the coercivity may be improved by setting the heat treatment described above as the first step and then maintaining the heat treatment for the second step at a temperature of 400 to 650 ° C. for a certain period of time and subsequently cooling to room temperature by furnace cooling. is there. The holding time is preferably in the range of 1 to 6 hours. The aging treatment is preferably performed in vacuum or in an inert gas atmosphere to prevent oxidation.

  If the aging temperature is lower than 700 ° C. or higher than 900 ° C., it is impossible to obtain a mixed structure of homogeneous cell phase and cell wall phase, and the magnetic properties of the permanent magnet may be degraded. The aging treatment temperature is more preferably 750 to 880 ° C., further preferably 780 to 850 ° C. If the aging treatment time is less than 0.5 hours, there is a possibility that the precipitation of the cell wall phase may not be sufficiently completed from the 1-7 phase. On the other hand, when the aging treatment time exceeds 80 hours, there is a possibility that the volume fraction of the cell phase may decrease because the thickness of the cell wall phase is increased. This is a factor that reduces the magnetic properties. The aging treatment time is more preferably in the range of 4 to 60 hours, still more preferably in the range of 8 to 40 hours.

  In addition, when the cooling rate after the aging heat treatment is less than 0.2 ° C./min, the volume fraction of the cell phase may decrease due to the increase in the thickness of the cell wall phase. On the other hand, when the cooling rate after the aging heat treatment exceeds 2 ° C./min, there is a possibility that a homogeneous cell phase and cell wall phase mixed structure can not be obtained. In any case, the magnetic properties of the permanent magnet may not be sufficiently enhanced. The cooling rate after the aging heat treatment is more preferably in the range of 0.4 to 1.5 ° C./minute, still more preferably in the range of 0.5 to 1.3 ° C./minute.

  The aging treatment is not limited to the two-step heat treatment, but may be a multi-step heat treatment, and it is also effective to carry out multi-step cooling. In addition, it is also effective to apply a preliminary aging treatment (pre-aging treatment) at a temperature lower than that of the aging treatment and for a short time as a pretreatment for the aging treatment. This is expected to improve the squareness of the magnetization curve. Specifically, the temperature of the pre-aging treatment is 650 to 790 ° C., the treatment time is 0.5 to 4 hours, and the slow cooling rate after the aging treatment is 0.5 to 1.5 ° C./minute. An improvement in the squareness of the magnet is expected.

  The permanent magnet of this embodiment can be used for various motors and generators. Moreover, it is also possible to use as a fixed magnet or variable magnet of a variable magnetic flux motor or a variable magnetic flux generator. Various motors and generators are configured by using the permanent magnet of this embodiment. When the permanent magnet of this embodiment is applied to a variable magnetic flux motor, the techniques disclosed in JP 2008-29148 A and JP 2008-43172 A are applied to the configuration and drive system of the variable flux motor. be able to.

  Next, the motor and the generator of the embodiment will be described with reference to the drawings. FIG. 5 shows a permanent magnet motor according to an embodiment. In the permanent magnet motor 11 shown in FIG. 5, a rotor 13 is disposed in a stator 12. In the iron core 14 of the rotor 13, the permanent magnet 15 of the embodiment is disposed. Based on the characteristics and the like of the permanent magnet of the embodiment, it is possible to achieve high efficiency, downsizing, cost reduction, and the like of the permanent magnet motor 11.

  FIG. 6 shows a variable flux motor according to an embodiment. In the variable magnetic flux motor 21 shown in FIG. 6, a rotor 23 is disposed in a stator 22. In the iron core 24 of the rotor 33, the permanent magnets of the embodiment are disposed as the fixed magnet 25 and the variable magnet 26. The variable magnet 26 is capable of changing the magnetic flux density (the amount of magnetic flux). Since the direction of magnetization of the variable magnet 26 is orthogonal to the direction of the Q axis, the variable magnet 26 can be magnetized by the D axis current without being affected by the Q axis current. The rotor 23 is provided with a magnetization winding (not shown). The magnetic field directly acts on the variable magnet 26 by passing a current from the magnetization circuit to the magnetization winding.

  According to the permanent magnet of the embodiment, for example, the fixed magnet 25 having a coercive force exceeding 500 kA / m and the variable magnet 26 having a coercive force of 500 kA / m or less are obtained by changing various conditions of the manufacturing method described above. Can. In the variable magnetic flux motor 21 shown in FIG. 6, the permanent magnet of the embodiment can be used for both the fixed magnet 25 and the variable magnet 26, but the permanent magnet of the embodiment is used for either one of the magnets. You may use. The variable magnetic flux motor 21 can output a large torque with a small device size, and thus is suitable for a motor such as a hybrid car or an electric car that requires high output and small size of the motor.

  FIG. 7 shows a generator according to an embodiment. The generator 31 shown in FIG. 7 includes a stator 32 using the permanent magnet of the embodiment. A rotor (rotor) 33 disposed inside the stator (stator) 32 is connected to a turbine 34 provided at one end of the generator 31 via a shaft 35. The turbine 34 is rotated by, for example, an externally supplied fluid. It is also possible to rotate the shaft 35 by transmitting dynamic rotation such as regenerative energy of a car instead of the turbine 34 rotated by fluid. Various known configurations can be adopted for the stator 32 and the rotor 33.

  The shaft 35 is in contact with a commutator (not shown) disposed on the side opposite to the turbine 34 with respect to the rotor 33, and the electromotive force generated by the rotation of the rotor 33 is phase separated as an output of the generator 31. It is boosted to the grid voltage and transmitted via a bus and a main transformer (not shown). The generator 31 may be either a normal generator or a variable flux generator. The rotor 33 is charged with static electricity from the turbine 34 and axial current accompanying power generation. For this reason, the generator 31 is provided with a brush 36 for discharging the charge of the rotor 33.

  Next, Examples and their evaluation results will be described.

(Examples 1-2)
Each raw material was weighed to have a composition shown in Table 1, and then arc melted in an Ar gas atmosphere to produce an alloy ingot. The alloy ingot was roughly crushed and further finely ground by a jet mill to prepare an alloy powder. The alloy powder was press-molded in a magnetic field to prepare a compression molded body. The compact of the alloy powder was placed in the chamber of the firing furnace, and evacuated until the degree of vacuum in the chamber was 9.5 × 10 ⁻³ Pa. In this state, the temperature in the chamber was raised to 1165 ° C. and held at that temperature for 5 minutes, and then Ar gas was introduced into the chamber.

  Next, the temperature in the chamber in an Ar atmosphere is raised to 1190 ° C., sintering is performed by holding for 6 hours at that temperature, and subsequently solution processing is performed by holding for 12 hours at 1160 ° C. It cooled to room temperature with the cooling rate of 240 degrees C / min. After the solution treatment, the sintered body was held at 710 ° C. for 1 hour and then gradually cooled to room temperature. Subsequently, the sintered body was held at 810 ° C. for 42 hours. The sintered body subjected to the aging treatment under such conditions was gradually cooled to 450 ° C., held at that temperature for 3 hours, and then furnace cooled to room temperature to obtain a target sintered magnet. The preparation conditions of the sintered body (processing conditions of the sintering step and the solution treatment step) are shown in Table 2.

  The composition of the sintered magnet is as shown in Table 1. Composition analysis of the magnet was performed by inductively coupled plasma (ICP) method. Moreover, according to the method mentioned above, the average grain size of a sintered magnet (sintered body), the volume fraction of a grain boundary, and the average distance L between non-oriented grains were measured. Furthermore, the magnetic properties of the sintered magnet were evaluated by BH tracer to measure the coercivity and residual magnetization. The measurement results are shown in Table 3. The composition analysis by the ICP method was performed according to the following procedure. First, a predetermined amount of the ground sample is weighed and placed in a quartz beaker. Add mixed acid (containing nitric acid and hydrochloric acid) and heat on a hot plate to about 140 ° C to completely dissolve the sample. After allowing to cool, transfer to a PFA measuring flask for volumetric adjustment and use as a sample solution. Such components of the sample solution are quantified by a calibration curve method using an ICP emission spectrophotometer. As the ICP emission spectrometer, SPS 4000 (trade name) manufactured by SII Nano Technology Inc. was used.

(Examples 3 to 5)
Each raw material was weighed to have a composition shown in Table 1, and then high frequency melting was performed in an Ar gas atmosphere to produce an alloy ingot. The alloy ingot was roughly crushed, heat-treated at 1170 ° C. for 2 hours, and then rapidly cooled to room temperature. The alloy powder was prepared by pulverizing with a jet mill. The alloy powder was press-molded in a magnetic field to prepare a compression molded body. The compact of the alloy powder was placed in the chamber of the sintering furnace, and evacuated until the degree of vacuum in the chamber was 9.0 × 10 ⁻³ Pa. In this state, the temperature in the chamber was raised to 1160 ° C., held at that temperature for 10 minutes, and then Ar gas was introduced into the chamber. The temperature in the chamber in an Ar atmosphere is raised to 1180 ° C., and held at that temperature for 16 hours for sintering, and subsequently held at 1120 ° C. for 10 hours for solution treatment, and then −250 ° C. It cooled to room temperature with the cooling rate of / min.

  Next, the sintered body after solution treatment was maintained at 750 ° C. for 1.5 hours and then gradually cooled to room temperature. Subsequently, the sintered body was held at 800 ° C. for 38 hours. The sintered body subjected to the aging treatment under such conditions was gradually cooled to 350 ° C., held at that temperature for 2 hours, and then furnace cooled to room temperature to obtain a target sintered magnet. The preparation conditions of the sintered body (processing conditions of the sintering step and the solution treatment step) are shown in Table 2. The composition of the sintered magnet is as shown in Table 1. The average grain size of the sintered magnet (sintered body), the volume fraction of grain boundaries, the average distance L between unoriented grains, the coercivity, and the residual magnetization were measured in the same manner as in Example 1. The measurement results are shown in Table 3.

(Examples 6 to 7)
Each raw material was weighed to have a composition shown in Table 1, and then high frequency melting was performed in an Ar gas atmosphere to produce an alloy ingot. The alloy ingot was roughly crushed and heat treated under the conditions of 1130 ° C. × 2 hours and then quenched to room temperature. The alloy powder was prepared by pulverizing with a jet mill. The alloy powder was press-molded in a magnetic field to prepare a compression molded body. The compact of the alloy powder was placed in the chamber of the firing furnace, and evacuated until the degree of vacuum in the chamber was 7.5 × 10 ⁻³ Pa. In this state, the temperature in the chamber was raised to 1150 ° C., held at that temperature for 25 minutes, and then Ar gas was introduced into the chamber. The temperature in the chamber in an Ar atmosphere is raised to 1180 ° C., and held at that temperature for 13 hours for sintering, and subsequently held at 1130 ° C. for 24 hours for solution treatment, and then to −260 ° C. It cooled to room temperature with the cooling rate of / min.

  Next, the sintered body after solution treatment was maintained at 690 ° C. for 1 hour and then gradually cooled to room temperature. Subsequently, the sintered body was held at 830 ° C. for 45 hours. The sintered body subjected to the aging treatment under such conditions was gradually cooled to 300 ° C., held at that temperature for 4 hours, and then furnace cooled to room temperature to obtain a target sintered magnet. The composition of the sintered magnet is as shown in Table 1. The average grain size of the sintered magnet (sintered body), the volume fraction of grain boundaries, the average distance L between unoriented grains, the coercivity, and the residual magnetization were measured in the same manner as in Example 1. The measurement results are shown in Table 3.

(Examples 8 to 11)
Each raw material was weighed to have a composition shown in Table 1, and then high frequency melting was performed in an Ar gas atmosphere to produce an alloy ingot. The alloy ingot was roughly crushed, heat-treated at 1170 ° C. for 2 hours, and then rapidly cooled to room temperature. The alloy powder was prepared by pulverizing with a jet mill. The alloy powder was press-molded in a magnetic field to prepare a compression molded body. The compact of the alloy powder was placed in the chamber of the sintering furnace, and evacuated until the degree of vacuum in the chamber was 9.0 × 10 ⁻³ Pa. In this state, the temperature in the chamber was raised to 1160 ° C. and held at that temperature for 5 minutes, and then Ar gas was introduced into the chamber. Then, the sintering step and the solution treatment step were performed under the conditions shown in Table 2. The cooling rate after solution treatment was -180 ° C / min.

  Next, the sintered body after solution treatment was maintained at 720 ° C. for 2 hours and then gradually cooled to room temperature. Subsequently, the sintered body was held at 820 ° C. for 35 hours. The sintered body subjected to the aging treatment under such conditions was gradually cooled to 350 ° C., held at that temperature for 1.5 hours, and then furnace cooled to room temperature to obtain a target sintered magnet. The composition of the sintered magnet is as shown in Table 1. The average grain size of the sintered magnet (sintered body), the volume fraction of grain boundaries, the average distance L between unoriented grains, the coercivity, and the residual magnetization were measured in the same manner as in Example 1. The measurement results are shown in Table 3.

(Comparative Examples 1 and 2)
A sintered magnet was produced in the same manner as in Example 1 except that the composition shown in Table 1 was applied. In Comparative Example 1, the Sm concentration in the alloy composition is set to a concentration exceeding 12.5 atomic percent, and in Comparative Example 2, the Zr concentration in the alloy composition is set to a concentration exceeding 4.5 atomic percent. The average grain size of the sintered magnet (sintered body), the volume fraction of grain boundaries, the average distance L between unoriented grains, the coercivity, and the residual magnetization were measured in the same manner as in Example 1. The measurement results are shown in Table 3.

(Comparative example 3)
Each raw material was weighed to have a composition shown in Table 1, and then high frequency melting was performed in an Ar gas atmosphere to produce an alloy ingot. The alloy ingot was roughly crushed, heat-treated at 1170 ° C. for 2 hours, and then rapidly cooled to room temperature. The alloy powder was prepared by pulverizing with a jet mill. The alloy powder was press-molded in a magnetic field to prepare a compression molded body. The compact of the alloy powder was placed in the chamber of the sintering furnace, and evacuated until the degree of vacuum in the chamber was 9.0 × 10 ⁻³ Pa. In this state, the temperature in the chamber was raised to 1160 ° C. and held at that temperature for 5 minutes, and then Ar gas was introduced into the chamber. The temperature in the chamber in an Ar atmosphere is raised to 1210 ° C., and held at that temperature for 6 hours for sintering, and subsequently held at 1130 ° C. for 12 hours for solution treatment, and then −180 ° C. It cooled to room temperature with the cooling rate of / min.

  Next, the sintered body after solution treatment was maintained at 720 ° C. for 2 hours and then gradually cooled to room temperature. Subsequently, the sintered body was held at 820 ° C. for 35 hours. The sintered body subjected to the aging treatment under such conditions was gradually cooled to 350 ° C., held at that temperature for 1.5 hours, and then furnace cooled to room temperature to obtain a target sintered magnet. The composition of the sintered magnet is as shown in Table 1. The average grain size of the sintered magnet (sintered body), the volume fraction of grain boundaries, the average distance L between unoriented grains, the coercivity, and the residual magnetization were measured in the same manner as in Example 1. The measurement results are shown in Table 3.

(Comparative Examples 4 to 6)
An alloy powder was prepared in the same manner as in Example 8 using the raw material mixture weighed to have the same composition as Example 8. Next, the alloy powder was press-molded in a magnetic field to prepare a compression-molded body, and then the sintering step and the solution treatment step were performed under the conditions shown in Table 2. Furthermore, aging treatment was performed under the same conditions as in Example 8 to prepare a sintered magnet. The average grain size of the sintered magnet (sintered body), the volume fraction of grain boundaries, the average distance L between unoriented grains, the coercivity, and the residual magnetization were measured in the same manner as in Example 1. The measurement results are shown in Table 3.

  As is apparent from Table 3, all of the sintered magnets of Examples 1 to 11 have appropriate average grain sizes and volume fractions of grain boundaries, whereby high magnetization and high coercivity can be obtained. It is understood that it has both. The composition of the permanent magnets of Comparative Examples 1 and 2 deviates, so that sufficient magnetic characteristics are not obtained. Since the comparative example 3 is hold | maintained for too long at the sintering temperature which is too high, since Sm concentration fell, coercivity is small. Further, when the Sm concentration decreases, the density of the sintered body also decreases, so the residual magnetization is also small. In Comparative Examples 4 to 6 in which the sintering temperature and solution treatment time are short, the ratio of crystal grain boundaries is large and the degree of orientation of crystal grains is also low, so the magnetization is not sufficiently improved as compared with Examples 8 to 11. .

  While certain embodiments of the invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in other various forms, and various omissions, replacements and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

  11: permanent magnet motor, 12: stator, 13: rotor, 14: iron core, 15: permanent magnet, 21: variable magnetic flux motor, 22: stator, 23: rotor, 24: iron core, 25: fixed magnet, 26: variable magnet , 31 ... variable magnetic flux generator, 32 ... stator, 33 ... rotor, 34 ... turbine, 35 ... shaft, 36 ... brush.

Claims (10)

Composition formula: R _p Fe _q M _r Cu _s Co _100-pqrs
(Wherein, R is at least one element selected from rare earth elements, M is at least one element selected from Zr, Ti and Hf, and p, q, r and s are each at atomic%, 10.7. 5 ≦ p ≦ 12.5, 24 ≦ q ≦ 40, 0.88 ≦ r ≦ 4.5, 3.5 ≦ s ≦ 10.7)
The composition represented by,
A permanent magnet comprising a sintered body comprising a crystal grain comprising a main phase containing a Th ₂ Zn ₁₇ crystal phase and a structure having crystal grain boundaries of the crystal grain,
The average grain size of the crystal grains is 25 μm or more,
When indexed the Th ₂ Zn ₁₇ crystal phase as the TbCu ₇ crystal phase, an average of between said the TbCu ₇ crystal phase [0001] shift of the crystal orientation angle to the direction of 45 degrees or more above the grain The distance is more than 120 μm,
Permanent magnet having a coercive force of at least 1010 kA / m . Composition formula: R _p Fe _q M _r Cu _s Co _100-pqrs
(Wherein, R is at least one element selected from rare earth elements, M is at least one element selected from Zr, Ti and Hf, and p, q, r and s are each at atomic%, 10.7. 5 ≦ p ≦ 12.5, 24 ≦ q ≦ 40, 0.88 ≦ r ≦ 4.5, 3.5 ≦ s ≦ 10.7)
The composition represented by,
A permanent magnet comprising a sintered body comprising a crystal grain comprising a main phase containing a Th ₂ Zn ₁₇ crystal phase and a structure having crystal grain boundaries of the crystal grain,
When indexed the Th ₂ Zn ₁₇ crystal phase as the TbCu ₇ crystal phase, an average of between said the TbCu ₇ crystal phase [0001] shift of the crystal orientation angle to the direction of 45 degrees or more above the grain The distance is more than 120 μm,
Permanent magnet having a coercive force of at least 1010 kA / m .   The permanent magnet according to claim 1, wherein the residual magnetization is 1.150 T or more.   The permanent magnet according to any one of claims 1 to 3, wherein an average crystal grain size of the crystal grains is 200 μm or less. Said main phase, a cell phase having the Th ₂ Zn ₁₇ crystal phase, and a cell wall phase present so as to surround the cell phase, according to any one of claims 1 to 4 permanent magnet.   The permanent magnet according to any one of claims 1 to 5, wherein 50 atomic% or more of the element R in the composition formula is Sm and 50 atomic% or more of the element M is Zr.   The method according to claim 1, wherein 20 atomic percent or less of Co in the composition formula is substituted with at least one element A selected from Ni, V, Cr, Mn, Al, Si, Ga, Nb, Ta, and W. The permanent magnet according to any one of claims 6.   A motor comprising the permanent magnet according to any one of claims 1 to 7.   A generator comprising the permanent magnet according to any one of claims 1 to 7.   A vehicle comprising the motor according to claim 8 or the generator according to claim 9.

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