KR20200079514A - Permanent magnet, manufacturing method of permanent magnet, and rotator - Google Patents

Abstract

The permanent magnet of this invention has a tetragonal R ₂ Fe ₁₄ B crystal structure. This permanent magnet has a composition formula (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B. Here, x is in the range of 0.01≤x≤0.16, and y is in the range of 0.01≤y≤0.16.

Description

Permanent magnet, manufacturing method of permanent magnet, and rotator

The present invention relates to an R-T-B permanent magnet, a method for manufacturing the permanent magnet, and a rotor having the permanent magnet.

RTB-based permanent magnets having a tetragonal R ₂ T ₁₄ B intermetallic compound as a main phase have excellent magnetic properties in that they have a high coercive force, and are used in various high value-added parts including industrial motors. Here, R is a rare earth element, and T is a transition element. Conventionally, a RTB-based permanent magnet to which Dy, a heavy rare earth element is added, is known (for example, see Patent Document 1). In addition, an RTB-based permanent magnet in which a plurality of rare earth elements containing Y and La are added is also known (see Patent Document 2, for example).

Japanese Patent Publication No. Hei 6-13211 Japanese Patent Publication No. Hei 9-115713

When a permanent magnet is used in an industrial motor, the operating temperature environment is often at a high temperature exceeding 100°C. However, in the conventional permanent magnets shown in Patent Documents 1 and 2, there is a fear that the coercive force is remarkably lowered as the temperature increases.

This invention was made|formed in order to solve the said subject, and it aims at providing the permanent magnet which suppressed the fall of the coercive force accompanying temperature rise, the manufacturing method of a permanent magnet, and a rotating machine.

In the permanent magnet according to the present invention, it has a tetragonal R ₂ Fe ₁₄ B crystal structure, the composition formula is (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B, x is 0.01≤x≤0.16, y is , 0.01≤y≤0.16.

According to the permanent magnet according to the present invention, the absolute value of the temperature coefficient of the coercive force of the permanent magnet can be reduced. Thereby, the permanent magnet which suppressed the fall of the coercive force accompanying temperature rise can be provided. Further, it is possible to provide a method for manufacturing such a permanent magnet, and a rotor having a permanent magnet.

1 is a flowchart of a method for manufacturing a permanent magnet according to the first embodiment.
2 is a view for explaining a raw material alloy manufacturing process in the method of manufacturing the permanent magnet of the first embodiment.
3 is a view for explaining a melting step and a cooling step in the method of manufacturing the permanent magnet according to the first embodiment.
4 is a table showing the relationship between the absolute value of the composition formula and the temperature coefficient of the coercive force in the sample of the permanent magnet of the first embodiment.
[FIG. 5] (Nd _1-xy La _x Sm _y ) _{2 It} is a graph showing the relationship between x and y in Fe ₁₄ B and the absolute value |α| of the temperature coefficient of the coercive force.
It is a figure which showed the atomic site in tetragonal Nd ₂ Fe ₁₄ B.
7 is a table showing the stabilization energy of La at each substitution site when the environmental temperature is changed.
8 is a table showing the stabilization energy of Sm at each substitution site when the environmental temperature is changed.
[Fig. 9] Fig. 9 is a schematic cross-sectional view of a rotator equipped with the permanent magnet of the first embodiment in a direction perpendicular to the axial direction of the rotator.
[Fig. 10] In the second embodiment, (Nd _1-xy La _x Sm _y ) ₂ The relationship between x/y in Fe ₁₄ B and the effect of the effect on the absolute ratio of the coercive temperature coefficient It is a table to show.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings. On the other hand, in each drawing, the same or equivalent parts are denoted by the same reference numerals, and overlapping descriptions are omitted.

Embodiment 1.

The RTB-based permanent magnet according to Embodiment 1 of the present invention is a permanent magnet having a tetragonal R ₂ T ₁₄ B structure as a main product phase. Here, R is a rare earth element. T is a transition element. B is boron. In the permanent magnet of the tetragonal R ₂ T ₁₄ B structure according to the first embodiment, a part of neodymium (Nd) is substituted by lanthanum (La) and samarium (Sm) to become R, and iron (Fe) is It is made of T. Therefore, in Embodiment 1, the composition formula of the permanent magnet is represented by (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B. Here, a method of manufacturing the RTB permanent magnet will first be described.

1 is a flow chart showing a procedure when manufacturing the R-T-B permanent magnet according to the first embodiment. As shown in FIG. 1, the manufacturing method of the R-T-B permanent magnet includes a raw material alloy manufacturing process, a melting process, a cooling process, a crushing process, a molding process, and a magnetizing process.

(Material alloy manufacturing process)

When manufacturing an R-T-B type permanent magnet, first, in a raw material alloy manufacturing process, a raw material alloy is produced. In the raw material alloy manufacturing process, first, raw materials having a weight according to the composition ratio of each element of the permanent magnet are respectively prepared, and these raw materials are mixed. As a raw material, Nd, La, Sm, Fe and ferrovoron (FeB) are used. Thereby, a mixed raw material in which Nd, La, Sm, Fe, and FeB are mixed is obtained. Next, the mixed raw material is melted. Thereby, a raw material alloy is obtained.

2 is a configuration diagram showing a state when the mixed raw material is melted in the raw material alloy production process of FIG. 1. When the mixed raw material is melted, an arc 22 is generated in the base plate 23 from the electrode 21 in a state where the mixed raw material 24 is disposed on the copper base plate 23. The mixed raw material 24 is melted on the saucer 23 by the arc 22. The melting of the mixed raw material 24 by the arc 22 is performed in a reduced pressure atmosphere containing argon (Ar) as an inert gas, for example. On the other hand, the raw material alloy can also be produced using a method other than melting of the mixed raw material 24 by arcing.

(Melting process)

After the raw material alloy manufacturing process, as shown in FIG. 3, in the melting process, the raw material alloy 26 is melted by the high frequency induction heating coil 25.

(Cooling process)

Thereafter, the raw material alloy 26 melted in the melting step is cooled in the cooling step. In the cooling step, the raw material alloy 26 is cooled using a liquid quenching method. In the liquid quenching method, the raw material alloy 25 in the molten state is injected from the nozzle 27 to the cooling roll 28. When the raw material alloy 26 is injected into the cooling roll 28, the cooling roll 28 is rotated. Thereby, the raw material alloy 26 in a molten state is cooled by the cooling roll 28 to become a ribbon-like alloy 29. The ribbon-like alloy 29 can also be produced using a method other than the liquid quenching method.

(Crushing process)

Thereafter, in the grinding step, the ribbon-like alloy 29 is crushed. As a result, the ribbon-like alloy 29 is a raw material powder having a particle size of about 200 μm or less. The pulverization of the ribbon-like alloy 29 is performed, for example, by using agate mortar. In addition to the induction, a stamp mill, a jaw crusher, a jet mill, or the like may be used to crush the ribbon-like alloy 29. The pulverization of the ribbon-like alloy 29 is preferably performed in an inert gas when the particle diameter of the raw material powder is particularly small. By pulverizing the ribbon-like alloy 29 in an inert gas, oxygen mixing into the raw material powder can be suppressed. When the atmosphere in pulverization does not affect the magnetic properties of the permanent magnet, it is not necessary to pulverize the ribbon-like alloy 29 in an inert gas.

(Forming process)

Thereafter, a molding step for molding the raw material powder is performed. In the molding process, the raw material powder and an epoxy resin having a heat resistance temperature of 200°C or higher are mixed with stirring. At this time, the volume content ratio of the raw material powder is set to about 20 vol%. Thereafter, the resin is cured to form a bond magnet. Meanwhile, only the raw material powder may be compression molded. Further, a mixture of an organic binder and a raw material powder may be compression molded. In the above-mentioned molding method, any method may be performed while applying a magnetic field.

(Sintering process)

In the case of compression molding only the raw material powder or compression molding of a mixture of an organic binder in the raw material powder, a sintering step is performed after the molding process. The sintering step is performed in a vacuum or an inert gas atmosphere to suppress oxidation. The sintering step may be performed while applying a magnetic field. Further, in the sintering process, for example, in order to improve magnetic properties, that is, to improve anisotropy or coercive force of the magnetic field, a process of hot working or aging treatment may be added. In addition, in the sintering step, a step in which a compound containing copper or aluminum is allowed to permeate into a grain boundary that is a boundary between the main phases may be added.

(Magnetic process)

The alloy that has undergone the molding process or the sintering process is subjected to cutting, polishing, or surface treatment to form an alloy in the shape of a product. The product-shaped alloy is magnetized by, for example, a condenser type magnetizing power supply, and becomes a permanent magnet.

Next, a method of analyzing the composition of the column in the RTB permanent magnet will be described. In general, the composition of the permanent magnet can be quantified by using a wavelength dispersive x-ray spectroscopy (WDS) device installed on a scanning electron microscope. However, in the analysis by the WDS device, since the analysis precision of the light element is low, it is difficult to quantify B in the RTB permanent magnet. Therefore, an X-ray diffraction (XRD) device is used in combination. It is confirmed by the XRD apparatus that the main product phase of the permanent magnet is a tetragonal R ₂ Fe ₁₄ B crystal structure. This confirms that the main composition of the RTB permanent magnet is R:T:B=2:14:1. With the WDS device, the composition ratio of elements other than B, that is, the composition ratio of Nd, La, and Sm constituting R, and the composition ratio of Fe constituting T can be obtained. From the above two results, it is possible to find the overall composition ratio of the production phase. In addition, with the XRD device, it can also be confirmed whether the element is not included in the tetragonal R ₂ Fe ₁₄ B crystal structure and does not exist as another structure.

Next, a method for evaluating magnetic properties will be described. The magnetic properties were evaluated by measuring the coercive force of a plurality of samples using a pulse-excited B-H tracer. The maximum applied magnetic field by the B-H tracer is 5T or more. The atmosphere at the time of measurement is nitrogen. The coercive force of each sample was measured at different temperatures of the first measurement temperature T1 and the second measurement temperature T2, which are different from each other. The temperature coefficient α[%] of the coercive force is a value obtained by dividing the ratio of the coercive force at T1 and the coercive force at T2 and the coercive force at T1 by the difference in temperature (T2-T1). Therefore, the smaller the absolute value |α| of the temperature coefficient of the coercive force is, the lowering of the coercive force of the permanent magnet against temperature rise is suppressed.

In the first embodiment, samples of a plurality of permanent magnets having different columnar compositions are produced by the above-described production method as samples of Examples 1 to 7 and Comparative Examples 1 to 8. Each sample was prepared by changing x and y in the composition formula (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B. Therefore, the combination of x and y in (Nd _1-xy La _x Sm _y ) of each sample is different for each of Examples 1 to 7 and Comparative Examples 1 to 8. Each sample was prepared in the form of a bonded magnet formed by mixing the raw material powder and the resin and curing the resin. The shape of each sample is a block shape having a vertical, horizontal, and height of 7 mm.

In addition, various conditions in the production of each sample according to Examples 1 to 7 and Comparative Examples 1 to 8 are as follows. The temperature at which the raw material alloy 26 in the melting step was melted was 1000°C to 1500°C. In the cooling step, the rotational speed of the cooling roll 28 was 10 m/s to 40 m/s. In this case, the cooling rate of the raw material alloy 26 is 10 ² °C/s to 10 ⁷ °C/s. However, the cooling rate of the raw material alloy 26 is preferably 10 ⁴ °C/s to 10 ⁷ °C/s. In addition, the injection of the raw material alloy 26 from the nozzle 27 to the cooling roll 28 was performed in a reduced pressure atmosphere containing Ar.

First, the analysis results for each sample according to Examples 1 to 7 and Comparative Examples 1 to 8 will be described. The analysis by the WDS apparatus was conducted by irradiating an electron beam to the surface of the ribbon-like alloy 29. In the analysis by the WDS device, the acceleration voltage of the electron beam was 15 kV, the irradiation current of the electron beam was 100 nA, and the spot diameter was 300 μm. In addition, the crystal structure analysis by the XRD apparatus was performed on the raw material powder. In the XRD apparatus, Cu was used for the tube. In the analysis by the XRD apparatus, the tube voltage was 40 kV, the tube current was 25 mA, and the measurement range 2θ was set to 20° to 70°.

According to the XRD apparatus, in each sample according to Examples 1 to 7 and Comparative Examples 1 to 8, crystal phases other than the tetragonal R ₂ Fe ₁₄ B crystal structure could not be confirmed. Thereby, it was confirmed that each sample according to Examples 1 to 7 and Comparative Examples 1 to 8 had a tetragonal R ₂ Fe ₁₄ B crystal structure. Therefore, the values of x and y in each sample according to Examples 1 to 7 and Comparative Examples 1 to 8 can be obtained by the WDS device. The obtained values of x and y are as shown in Fig. 4 to be described later.

Next, measurement results of magnetic properties in each sample according to Examples 1 to 7 and Comparative Examples 1 to 8 will be described. In the measurement of the coercive force, the first measurement temperature T1 was set to 23°C, and the second measurement temperature T2 was set to 200°C. 23°C is room temperature. 200°C is an environment during motor operation in automobiles and industries, and is a temperature that can occur. The temperature coefficient α of the coercive force was calculated using the coercive force at a temperature of 23°C and the coercive force at a temperature of 200°C.

4 is a table showing the relationship between the composition formula of the column in each sample according to Examples 1 to 7 and Comparative Examples 1 to 8 and the absolute value |α| of the temperature coefficient of the coercive force.

First, compared to the case when the base material for the alloy Nd ₂ Fe ₁₄ B, the addition of La and Sm at the same time, if with respect to the parent alloy Nd ₂ Fe ₁₄ B, adding only La. In this case, for samples having the same Nd addition ratio in (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B, the absolute value |α| of the temperature coefficient of the coercive force is compared. When comparing Example 1 and Comparative Example 3 in which the addition ratio of Nd = 0.980, in Example 1 in which La and Sm are added simultaneously, compared to Comparative Example 3 in which only La is added, the absolute value of the temperature coefficient of the coercive force ｜α｜ is small. When Example 3 and Comparative Example 4 in which the ratio of Nd addition = 0.950 are compared, in Example 3, the absolute value |α| is small. Similarly, when comparing Example 4 and Comparative Example 5, in which the addition ratio of Nd = 0.906, Example 4 has a smaller absolute value |α|. According to compare three or more sets, in the case where with respect to the parent alloy Nd ₂ Fe ₁₄ B, the addition of La and Sm at the same time, as compared with the case when for the parent alloy Nd ₂ Fe ₁₄ B, adding only La, the temperature coefficient of coercive force The absolute value |α| is small.

With respect to the following, if the base material for the alloy Nd ₂ Fe ₁₄ B, the addition of La and Sm and at the same time, the parent alloy Nd ₂ Fe ₁₄ B, and compares the If adding only Sm. In this case, the absolute value |α| of the temperature coefficient of the coercive force is compared with respect to the sample having the same addition ratio of Nd in (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B. When comparing Example 1 and Comparative Example 6 in which the addition ratio of Nd = 0.980, Example 1 in which La and Sm were added simultaneously, compared with Comparative Example 6 in which only Sm was added, the absolute value of the temperature coefficient of the coercive force ｜α｜ is small. Addition ratio of Nd=0. When comparing Example 3 and Comparative Example 7, which are 950, in Example 3, the absolute value |α| is small. Similarly, the addition ratio of Nd=0. When Example 4 and Comparative Example 8, which are 906, are compared, the absolute value |α| of Example 4 is small. According to compare three or more sets, in the case where with respect to the parent alloy Nd ₂ Fe ₁₄ B, the addition of La and Sm at the same time, as compared with the case when for the parent alloy Nd ₂ Fe ₁₄ B, adding only Sm, the temperature coefficient of coercive force The absolute value |α| is small.

By comparison of these measurement results, when La and Sm were simultaneously added to the base material alloy Nd ₂ Fe ₁₄ B, compared to the case where only either La or Sm was added to the base material alloy Nd ₂ Fe ₁₄ B, , It was found that the absolute value of the coercive force temperature coefficient |α| becomes smaller.

Next, the ranges of x and y in (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B will be described with reference to FIG. 5. 5 is a graph showing the relationship between x and y in (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B and the absolute value |α| of the temperature coefficient of the coercive force. In FIG. 5, x is equivalent to y. As shown in Fig. 5, the absolute value |α| of the temperature coefficient of the coercive force decreases as x increases from 0. In the case of x=0.086, the absolute value |α| of the temperature coefficient has a minimum value. In the case of x>0.086, the absolute value |α| of the temperature coefficient increases with increasing x. In the case of x>0.16, the absolute value |α| of the temperature coefficient exceeds the absolute value |α| of the temperature coefficient when x=0. If the above, the x and y of 0.01≤x≤0.16 and 0.01≤y≤0.16, the absolute value of the temperature coefficient of coercive force | α | is, La and Sm in the one without addition of the temperature coefficient of the coercive force of the Nd ₂ Fe ₁₄ B It is smaller than the absolute value |α|.

As a result of the measurement of magnetic properties, the absolute value |α| of the temperature coefficient of the coercive force in Comparative Example 2 in which x=y=0.186 is in Comparative Example 1 in which La and Sm are not added to the base alloy Nd ₂ Fe ₁₄ B. Is larger than the absolute value of the coercive force temperature coefficient |α|. As the factor, the following is considered. According to the crystal structure analysis by the XRD apparatus, the peak related to tetragonal Nd ₂ Fe ₁₄ B was detected in the sample of Comparative Example 2, but the peak intensity was lower than that of each of the samples of Examples 1 to 7. Therefore, in the sample of Comparative Example 2, the crystallinity of the tetragonal Nd ₂ Fe ₁₄ B crystal structure was lowered due to the excessive addition of La and Sm to the base alloy Nd ₂ Fe ₁₄ B. It is thought that magnetic properties were not obtained.

Next, the atomic sites of the tetragonal R ₂ Fe ₁₄ B crystal structure in which La and Sm are substituted will be described with reference to FIGS. 6 to 8. The site to be substituted is determined by the numerical value of the energy obtained by obtaining the stabilization energy by substitution by band calculation and approximation of the molecular field of the Heisenberg model.

First, the method of calculating the stabilization energy in La will be described. The stabilization energy can be determined by the energy difference between (Nd ₇ La ₁ )Fe ₅₆ B ₄ +Nd and Nd ₈ (Fe ₅₅ La ₁ )B ₄ +Fe using an Nd ₈ Fe ₅₆ B ₄ crystal cell. The smaller the value, the more stable the atom is when an atom is substituted at the site. That is, La is easily substituted with the atomic site where the energy is the smallest among the atomic sites. In this calculation, when La is substituted with the original atom, the lattice constant in the tetragonal R ₂ Fe ₁₄ B crystal structure does not change due to the difference in the atomic radius. 6 is a view showing the atomic sites in tetragonal Nd ₂ Fe ₁₄ B used in FIGS. 7 and 8 (Source: JF Herbst et al.: PHYSICAL REVIEW B, Vol. 29, No. 7, pp. 4176-4178, 1984).

7 is a table showing the stabilization energy of La at each substitution site when the environmental temperature is changed. According to FIG. 7, the stable substitution site of La is an Nd(f) site at a temperature of 1000 K or more, and a Fe(c) site at temperatures 293K and 500K. In Embodiment 1, as explained in the manufacturing method, the raw material alloy of the permanent magnet is quenched after being melted at a temperature of 1000°C or higher. Therefore, it is considered that the raw material alloy maintains a state of 1000K or more, that is, 727°C or more. Therefore, when a permanent magnet is produced by the above-described manufacturing method, it is considered that La is substituted at the Nd(f) site even at room temperature. This means that when the La-Fe-B alloy is melted at 1073K (800°C) and cooled with ice water, tetragonal La ₂ Fe ₁₄ B is formed, that is, La enters the Fe(c) site. There is a research report (source: YAO Qingrong et al.: JOURNAL OF RARE EARTHS, Vol. 34, No. 11, pp. 1121-1125, 2016) that enters a site equivalent to the Nd(f) site in FIG. 6 without going It is supported from things.

Next, a method of calculating the stabilization energy in Sm will be described. For Sm, the energy difference between (Nd ₇ Sm ₁ )Fe ₅₆ B ₄ +Nd and Nd ₈ (Fe ₅₅ Sm ₁ )B ₄ +Fe is determined. The fact that the lattice constant does not change due to the substitution of atoms is the same as in the case of La.

8 is a table showing the stabilization energy of Sm at each substitution site when the environmental temperature is changed. According to FIG. 8, it can be seen that the stable substitution site of Sm is an Nd(g) site at any temperature. From the above, in each sample of Examples 1 to 7 and Comparative Examples 1 to 8, La is substituted at the Nd(f) site, and Sm is substituted at the Nd(g) site. La is substituted for the energy-stable Nd(f) site, and Sm is substituted for the energy-stable Nd(g) site. Therefore, with respect to the base material alloy Nd ₂ Fe ₁₄ B, in the permanent magnet to which La and Sm are added, stability of magnetic properties between products can be maintained.

Next, a rotator equipped with a permanent magnet according to the first embodiment will be described with reference to FIG. 9. Fig. 9 is a schematic cross-sectional view of a rotator equipped with a permanent magnet according to the first embodiment in a direction perpendicular to the axial direction of the rotator. In Fig. 9, the clarity of the drawing is given priority, and details of hatching and the rotating shaft are omitted.

The rotor includes a rotor 30 and an annular stator (not shown). The configuration of the stator is not particularly limited, and is an existing configuration. The rotor 30 is rotatable about the rotation shaft 31. The rotor 30 includes a rotor core 32 and six permanent magnets 33. The rotor core 32 is formed by laminating a plurality of disk-shaped electronic steel sheets in the axial direction of the rotating shaft 31. The rotor core 32 is provided with six magnet insertion holes 34 along the main direction of the rotor 30.

The six permanent magnets 33 are manufactured by the above-described manufacturing method. Each of the six permanent magnets 33 is inserted into a corresponding magnet insertion hole 34, respectively. The six permanent magnets 33 are magnetized so that magnetic poles of the permanent magnets 33 on the outer side in the radial direction of the rotor 30 are different from neighboring permanent magnets 33. The six permanent magnets 33 have a tetragonal R ₂ Fe ₁₄ B crystal structure in the main production phase, and the composition formula is (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B, and x and y are, for example, For all, it's all 0.025.

The number of magnetic poles of the rotor 30 may be two or more poles, that is, two or more permanent magnets 33. Further, the rotor 30 is a magnet-embedded rotor, but may be a surface magnet-type rotor in which a permanent magnet is fixed with an adhesive on the outer circumference of the rotor.

When the coercive force of the permanent magnet decreases at a high temperature, the operation of the rotor 30 becomes unstable. When the permanent magnet 33 according to the first embodiment is used, since the absolute value of the temperature coefficient of the coercive force is small, a decrease in the coercive force is suppressed even at a high temperature. Therefore, even at a high temperature, the operation of the rotor 30 can be stabilized.

As described above, the permanent magnet according to the first embodiment has a tetragonal R ₂ Fe ₁₄ B crystal structure, a compositional formula (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B, and x is 0.01≤x≤ 0.16, and y is 0.01≤y≤0.16. Therefore, a permanent magnet material having a small absolute value of the temperature coefficient of the coercive force can be obtained. Therefore, the fall of the coercive force of the permanent magnet accompanying temperature rise can be suppressed.

In addition, La is substituted at the Nd(f) site, and Sm is substituted at the Nd(g) site. Therefore, in the permanent magnet, stability of magnetic properties between products can be maintained.

In the method for manufacturing a permanent magnet according to the first embodiment, the raw material alloy 26 of the permanent magnet is melted to melt the raw material alloy 26 in a molten state, and the molten raw material alloy 26 is cooled. It has a cooling process. Thereby, the permanent magnet which can suppress the fall of the coercive force accompanying temperature rise can be obtained easily.

In the manufacturing method of the permanent magnet according to the first embodiment, in the cooling step, the cooling rate is 10 ² to 10 ⁷ °C/s. Thereby, the state in which La substituted for the Nd(f) site can be maintained.

In the manufacturing method of the permanent magnet in the first embodiment, in the melting step, the temperature at which the raw material alloy 26 is melted is 727°C or higher, that is, 1000K or higher. Thereby, La can be substituted for the Nd(f) site.

In addition, the rotator has a tetragonal R ₂ Fe ₁₄ B crystal structure, the composition formula is (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B, x is 0.01≤x≤0.16, and y is 0.01≤ It has a permanent magnet 33 with y≤0.16. Therefore, even at high temperature, it is possible to construct a rotating machine with stable operation.

Embodiment 2.

Next, the permanent magnet according to Embodiment 2 of the present invention will be described with reference to FIG. 10. In the first embodiment, x and y were equivalent values. In the second embodiment, x and y are different.

Fig. 10 shows the presence or absence of an effect in the ratio x/y of x and y and the ratio C1/C0 of the temperature coefficient of the coercive force in the composition formula (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B It is a table showing the relationship. x is 0.01≤x≤0.16, and y is 0.01≤y≤0.16. C0 is the absolute value of the temperature coefficient of the coercive force in Nd ₂ Fe ₁₄ B. C1 is the absolute value of the temperature coefficient of the coercive force in the composition formula (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B (0.01≤x≤0.16, 0.01≤y≤0.16). When C1/C0 is less than 1, the effect of the complex addition of La and Sm with respect to the temperature coefficient of the coercive force is shown, and an o is given to the corresponding column in FIG. In addition, when C1/C0 is 1 or more, it is assumed that the effect of the complex addition of La and Sm does not appear with respect to the temperature coefficient of the coercive force. The sample of the permanent magnet used for the measurement was produced by the manufacturing method described in Embodiment 1.

As shown in Fig. 10, the permanent magnet of the composition formula (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B having a tetragonal R ₂ Fe ₁₄ B crystal structure is 0.5≤x/y≤ in x and y. In the range of 2.0, the absolute value of the temperature coefficient of the coercive force can be reduced by the effect of the complex addition of La and Sm to the base alloy Nd ₂ Fe ₁₄ B.

Thus, in the permanent magnet according to the second embodiment, the ratio x/y of x and y is 0.5≦x/y≦2.0. Thereby, a permanent magnet with a small absolute value of the temperature coefficient of the coercive force can be obtained.

In the present invention, since the expensive heavy rare earth elements of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are not used, it is inexpensive to manufacture a permanent magnet with a small absolute value of the coercive temperature coefficient. It is possible.

26 raw alloys, 33 permanent magnets.

Claims (7)

Tetragonal R ₂ Fe ₁₄ B has a crystal structure,
The composition formula is (Nd _1-xy La _x Sm _y ) ₂ Fe ₁₄ B,
x is 0.01≤x≤0.16,
y is 0.01≤y≤0.16 permanent magnet. According to claim 1,
La is substituted at the Nd(f) site,
Sm is a permanent magnet substituted at the Nd(g) site. The method according to claim 1 or 2,
The ratio x/y of x and y is 0.5≤x/y≤2.0. A method for manufacturing the permanent magnet according to any one of claims 1 to 3,
A melting step of melting the raw material alloy of the permanent magnet to make the raw material alloy in a molten state, and
And a cooling step of cooling the raw material alloy in the molten state. The method of claim 4,
In the cooling process, and the method for producing a permanent magnet for a cooling rate of ² to 10 ⁷ ~10 ℃ / s. The method of claim 4 or 5,
In the said melting process, the manufacturing method of the permanent magnet whose melting|fusing temperature is 727 degreeC or more. A rotating machine having the permanent magnet according to any one of claims 1 to 3.

Images