JP2016134498A - Method of manufacturing magnetic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing magnetic material having an excellent magnetic characteristic.SOLUTION: A magnetic material manufacturing method comprises a preparation step of preparing Sm-Fe-based alloy containing Sm and Fe, a magnetic field heat treatment processing step of performing a heat treatment on the Sm-Fe-based alloy at a temperature of not less than 250°C to not more than 350°C under an atmosphere or pressure-reduced atmosphere in which Sm and Fe do not react with each other while applying a magnetic field of not less than 2T to not more than 4T, and a rapid heat treatment step for subjecting the Sm-Fe-based alloy to a heat treatment of rapidly heating the temperature from the heating temperature in the magnetic field heat treatment step to a temperature of not less than 600°C to not more than 800°C within 5 minutes under the atmosphere or pressure-reduced atmosphere in which Sm and Fe do not react with each other after the magnetic field heat treatment step, holding the Sm-Fe-based allot at this temperature for a time of not less than 2 minutes to not more than 10 minutes, and then rapidly cooling the temperature to 500°C or less within 5 minutes.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a magnetic material that is a material for a rare earth magnet. In particular, the present invention relates to a method for producing a magnetic material having excellent magnetic properties.

As a permanent magnet used in motors and generators, a rare earth-iron alloy (RE-Fe alloy) containing a rare earth-iron compound containing rare earth elements (RE) and iron (Fe) as a main phase is used. The rare earth magnets used are widely used. A typical rare earth magnet is an Nd—Fe—B magnet (neodymium magnet) using an Nd ₂ Fe ₁₄ B alloy having a Nd ₂ Fe ₁₄ B phase as a main phase (see Patent Documents 1 and 2). _Other, Sm 2 _{Fe 17} phase is a _Sm 2 _{Fe 17} alloy as a main phase raw material, Sm-Fe with _Sm 2 _Fe 17 _{N 3} alloy of which main phase _Sm 2 _Fe 17 _{N 3} phase This was nitrided -N magnets are known (see Patent Documents 1 and 2).

  In addition, research on nanocomposite magnets is underway with the aim of improving the performance of rare earth magnets (see Patent Document 1). The nanocomposite magnet has a nano-sized fine soft magnetic phase and hard magnetic phase, and has, for example, a nanocomposite structure in which both phases are periodically arranged at intervals of nanometer order. In nanocomposite magnets, the soft magnetic phase is bound to the hard magnetic phase by the exchange interaction between the soft magnetic phase and the hard magnetic phase, and the soft magnetic phase and the hard magnetic phase behave as if they were a single-phase magnet. . As a result, it is possible to have both the high magnetization of the soft magnetic phase and the high coercivity of the hard magnetic phase, which is expected as a magnetic material having excellent magnetic properties.

JP-A-11-97222 JP 2014-146655 A

  There is a demand for higher performance of rare earth magnets, and the development of magnetic materials with excellent magnetic properties is strongly desired.

  The present invention has been made in view of the above circumstances, and one of the objects of the present invention is to provide a method for producing a magnetic material having excellent magnetic properties.

  The manufacturing method of the magnetic material which concerns on 1 aspect of this invention is equipped with a preparatory process, a magnetic field heat treatment process, and a rapid heat treatment process. The preparation step is a step of preparing an Sm—Fe-based alloy containing Sm and Fe. The magnetic field heat treatment step is a step of heat-treating the Sm—Fe-based alloy at a temperature of 250 ° C. or higher and 350 ° C. or lower while applying a magnetic field of 2T or more and 4T or less in an atmosphere that does not react with Sm and Fe or in a reduced pressure atmosphere. It is. In the rapid heat treatment step, after the magnetic field heat treatment step, the Sm—Fe-based alloy is subjected to 5 minutes from the heating temperature in the magnetic field heat treatment step to 600 ° C. to 800 ° C. in an atmosphere that does not react with Sm and Fe or in a reduced pressure atmosphere. The temperature is rapidly increased within 5 minutes, held at that temperature for 2 minutes to 10 minutes, and then subjected to a heat treatment for rapidly cooling to 500 ° C. or less within 5 minutes.

  The method for producing a magnetic material can produce a magnetic material having excellent magnetic properties.

FIG. 3 is a process explanatory view schematically showing an example of a manufacturing process of a magnetic material according to the first embodiment.

[Description of Embodiment of the Present Invention]
The present inventors selected an Sm—Fe alloy as the rare earth-iron-based alloy and focused on a rare earth magnet using an Sm ₅ Fe ₁₇ alloy having a Sm ₅ Fe ₁₇ phase as a main phase as a magnetic material. This is because the Sm ₅ Fe ₁₇ alloy has a high coercive force as a rare earth magnet. Therefore, with the aim of further improving the performance of rare earth magnets, we have developed a magnetic material having a nanocomposite structure including a soft magnetic phase composed of Fe phase and a hard magnetic phase composed of Sm ₅ Fe ₁₇ phase.

In Patent Document 1, an amorphous quenched ribbon alloy is manufactured by a rapid cooling method, and then the alloy is subjected to a heat treatment at a temperature of 600 ° C. or higher to produce a nanocomposite magnet including a soft magnetic phase and a hard magnetic phase. How to do is described. However, in the manufacturing method described in Patent Document 1, a nanocomposite magnet including a soft magnetic phase composed of Fe phase and a hard magnetic phase composed of Sm ₅ Fe ₁₇ phase cannot be produced at present. The reason is that when crystallized by heat treatment, stable Sm ₂ Fe ₁₇ phase and SmFe ₃ phase are mainly precipitated.

Therefore, the inventors have intensively studied to make a nanocomposite structure including a soft magnetic phase composed of Fe phase and a hard magnetic phase composed of Sm ₅ Fe ₁₇ phase. As a result, the Fe phase and Sm ₅ are obtained by performing a two-stage heat treatment of a magnetic field heat treatment step in which heat treatment is performed at a low temperature while applying a magnetic field and a rapid heat treatment step in which the temperature is rapidly raised to a high temperature and then rapidly cooled. The present invention was completed upon obtaining the knowledge that a magnetic material having a nanocomposite structure mixed with Fe ₁₇ phase can be obtained. The contents of the embodiments of the present invention will be listed and described below.

  (1) The manufacturing method of the magnetic material which concerns on embodiment is equipped with a preparatory process, a magnetic field heat treatment process, and a rapid heat treatment process. The preparation step is a step of preparing an Sm—Fe-based alloy containing Sm and Fe. The magnetic field heat treatment step is a step of heat-treating the Sm—Fe-based alloy at a temperature of 250 ° C. or higher and 350 ° C. or lower while applying a magnetic field of 2T or more and 4T or less in an atmosphere that does not react with Sm and Fe or in a reduced pressure atmosphere. It is. In the rapid heat treatment step, after the magnetic field heat treatment step, the Sm—Fe-based alloy is subjected to 5 minutes from the heating temperature in the magnetic field heat treatment step to 600 ° C. to 800 ° C. in an atmosphere that does not react with Sm and Fe or in a reduced pressure atmosphere. The temperature is rapidly increased within 5 minutes, held at that temperature for 2 minutes to 10 minutes, and then subjected to a heat treatment for rapidly cooling to 500 ° C. or less within 5 minutes.

When heat-treating the raw material Sm-Fe alloy, a nanocomposite structure including a fine and highly crystalline Fe phase and a Sm ₅ Fe ₁₇ phase can be obtained by performing a two-step process of a magnetic field heat treatment step ⇒ a rapid heat treatment step. The magnetic material which has can be obtained. First, in the magnetic field heat treatment step, by performing heat treatment while applying a magnetic field, an Fe phase having high energy stability in the magnetic field is precipitated. At this time, since the heat treatment is performed at a low temperature of 250 ° C. or more and 350 ° C. or less, coarsening of the Fe phase can be suppressed and a fine Fe phase can be precipitated. By applying a magnetic field even at a low temperature, the Fe phase can be precipitated by the energy of the magnetic field because it cannot be precipitated by the thermal energy. By adjusting the heating temperature and the applied magnetic field in this magnetic field heat treatment step, the amount of precipitation of the Fe phase can be controlled, and the remaining Sm ₅ Fe ₁₇ phase can be obtained. Next, in the rapid heat treatment process, rapid tempering ⇒ keeping high temperature in a short time ⇒ rapid cooling promotes crystallization of Fe phase and Sm ₅ Fe ₁₇ phase without coarsening Fe phase Therefore, a fine and highly crystalline Fe phase and Sm ₅ Fe ₁₇ phase can be produced. Since a Sm ₅ Fe ₁₇ phase can be generated, a magnetic material having a high coercive force can be obtained.

  (2) As a manufacturing method of the magnetic material of the embodiment, the Sm—Fe-based alloy in the preparation step is in an amorphous state, and the Sm content is 10% by mass or more and 45% by mass or less. .

According to the above configuration, the raw material Sm—Fe-based alloy is in an amorphous state, and the Sm content is within the above range, so that it is easy to generate the Sm ₅ Fe ₁₇ phase, and the Fe phase and the Sm ₅ Fe _{It is} easy to produce a magnetic material having a nanocomposite structure containing ₁₇ phases.

[Details of the embodiment of the present invention]
Details of the embodiment of the present invention will be described below. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

<Embodiment 1>
[Method of manufacturing magnetic material]
The manufacturing method of the magnetic material of Embodiment 1 includes a preparation step, a magnetic field heat treatment step, and a rapid heat treatment step. Hereafter, each process is demonstrated in detail based on FIG.

(Preparation process)
The preparation step is a step of preparing an Sm—Fe-based alloy containing Sm and Fe. In the Sm—Fe-based alloy, the Sm content is 10% by mass or more and 45% by mass or less. When the Sm content is 10% by mass or more, the Sm ₅ Fe ₁₇ phase is easily generated, and the coercive force can be improved. On the other hand, when the Sm content is 45% by mass or less, the Fe content is relatively increased, and the residual magnetization can be improved. The Sm content is further 12% to 27% by mass, particularly 18% to 25% by mass. The Sm-Fe alloy may contain about 5% by mass or less of B, C, F, Nb, and Zr in addition to Sm and Fe. Further, a part of Fe may be substituted with other transition metal elements such as Co and Cu, Al and Si. The content of Fe (including those obtained by substituting part of Fe) is 71 to 88% by mass.

It can be mentioned that the Sm—Fe-based alloy is in an amorphous state. If the Sm-Fe-based alloy is in an amorphous state and the Sm content is within the above range, a crystalline Sm ₅ Fe ₁₇ phase can be easily formed by a two-stage heat treatment process described later. easy to manufacture a magnetic material having a nanocomposite structure containing ₅ Fe ₁₇ phase.

The Sm-Fe-based alloy can be obtained by quenching a molten alloy blended so as to be in the above composition range by a super rapid cooling method. Examples of the ultra-quenching method include a melt span method. The cooling rate is, for example, 2 × 10 ⁵ ° C./second or more, preferably 1 × 10 ⁶ ° C./second or more. As shown in the left diagram of FIG. 1, the Sm—Fe-based alloy (quenched ribbon 30) obtained by the melt span method may be appropriately pulverized to obtain the Sm—Fe-based alloy powder 20. The average particle diameter of the Sm—Fe-based alloy powder 30 is, for example, 5 μm to 50 μm, preferably 10 μm to 30 μm. The “average particle diameter” is a particle diameter (D50: 50 volume% particle diameter) at which the cumulative volume is 50% from the small diameter side in the volume-based particle size distribution measured by the laser diffraction method. For the pulverization of the Sm—Fe alloy, a known pulverizer such as a jet mill, a ball mill, a hammer mill, a brown mill, a pin mill, a disk mill, or a jaw crusher can be used. The magnetic material may be pulverized into powder after the magnetic material is manufactured without being pulverized at the stage of the Sm-Fe alloy.

(Magnetic heat treatment process)
As shown in the middle diagram of FIG. 1, the magnetic field heat treatment step is performed at 250 ° C. or higher and 350 ° C. or lower while applying a magnetic field of 2T or more and 4T or less to the Sm—Fe-based alloy powder 20 in an inert atmosphere or a reduced pressure atmosphere. This is a step of performing heat treatment at a temperature of. By performing heat treatment while applying a magnetic field at a low temperature of 250 ° C. or higher and 350 ° C. or lower, the Fe phase does not become coarse, and an Fe phase with high energy stability in the magnetic field is precipitated.

  The atmosphere is an atmosphere that does not react with Sm and Fe or a reduced pressure atmosphere. The atmosphere that does not react with Sm and Fe is an atmosphere that does not contain oxygen, hydrogen, or nitrogen, and includes Ar. The reduced pressure atmosphere refers to a vacuum state in which the pressure is lower than that of a standard air atmosphere, and the final vacuum is preferably 10 Pa or less, and more preferably 1 Pa or less.

  The heating temperature is 250 ° C. or higher and 350 ° C. or lower. When the heating temperature is 250 ° C. or higher, the Fe phase can be precipitated. On the other hand, when the heating temperature is 350 ° C. or less, coarsening of the Fe phase can be suppressed. The rate of temperature increase to the heating temperature is not particularly limited. Examples of the heat treatment holding time include 30 minutes or more and 10 hours or less. Since the Fe phase is difficult to precipitate due to the low heating temperature, the holding time is 30 minutes or more. On the other hand, when the time is 10 hours or less, the Fe phase can be sufficiently precipitated without excessively increasing the holding time. This holding time is preferably 1 hour or more and 3 hours or less.

  The applied magnetic field is 2T or more and 4T or less. When the heating temperature is low, the Fe phase is hardly precipitated by thermal energy, but by applying a magnetic field of 2T or more, the Fe phase is precipitated by the magnetic field energy. That is, the Fe phase can be deposited by the energy of the magnetic field as much as it cannot be deposited by thermal energy. Therefore, the Fe phase can be sufficiently precipitated even at a low temperature. On the other hand, when the magnetic field is 4T or less, coarsening of the Fe phase can be suppressed. Such a magnetic field can be stably formed by using, for example, a high-temperature superconducting magnet.

In the magnetic field heat treatment step, by adjusting the heating temperature and the applied magnetic field, the precipitation amount of the Fe phase can be controlled, and the remaining Sm ₅ Fe ₁₇ phase can be obtained. The heating temperature and the applied magnetic field are such that the applied magnetic field is increased when the heating temperature is low, and the applied magnetic field is decreased when the heating temperature is high, so that the Fe phase is not effectively coarsened by the heat energy and magnetic field energy. The desired amount can be deposited in

  The average particle size of the Fe phase is substantially determined by this magnetic field heat treatment step. The average particle diameter of the Fe phase is 150 nm or less, preferably 100 nm or less.

(Rapid heat treatment process)
As shown in the right diagram of FIG. 1, the rapid thermal process is performed by rapidly increasing the temperature of the Sm—Fe-based alloy powder 20 (low temperature T ₁ → high temperature T ₂ ) → high temperature holding in a short time (high temperature T ₂ ) → This is a step of rapid cooling (500 ° C. or less). This rapid heat treatment step is performed continuously after the magnetic field heat treatment step. That is, the low temperature T ₁ of the before performing rapid heating, is that the heating temperature in the magnetic field heat treatment step. By rapid Atsushi Nobori and short time high temperature holding, without coarsening the Fe phase, can facilitate the Fe phase and _Sm of 5 _{Fe 17} phase crystallization, fine and highly crystalline Fe phase and _Sm 5 _{Fe 17} A phase can be generated.

  As in the magnetic field heat treatment step, the atmosphere is an atmosphere that does not react with Sm and Fe or a reduced pressure atmosphere. The atmosphere that does not react with Sm and Fe is an atmosphere that does not contain oxygen, hydrogen, or nitrogen, and includes Ar. The reduced pressure atmosphere refers to a vacuum state in which the pressure is lower than that of a standard air atmosphere, and the final vacuum is preferably 10 Pa or less, and more preferably 1 Pa or less.

First, the Sm—Fe-based alloy powder 20 is rapidly heated within 5 minutes from the heating temperature T ₁ (250 ° C. to 350 ° C.) in the magnetic field heat treatment step to the high temperature T _{2 of} 600 ° C. to 800 ° C. Examples of the heating rate include 50 ° C./min or more, 70 ° C./min or more, 90 ° C./min or more, 110 ° C./min or more. Heating time t ₁ is not particularly limited if it is within 5 minutes.

When a high temperature _{T 2,} holding the temperature _{T 2} in 10 minutes or less than 2 minutes (between _t 1 -t ₂ of Fig. 1 right panel). Then, crystallization of the Fe phase and the Sm ₅ Fe ₁₇ phase occurs, and a composite structure containing a crystal phase including the soft magnetic phase 11 composed of the Fe phase and the hard magnetic phase 12 composed of the Sm ₅ Fe ₁₇ phase is formed. A structure in which a soft magnetic phase and a hard magnetic phase are composited is obtained. The rapid heat treatment step is preferably performed without applying a magnetic field. This is because the Fe phase becomes coarse when a magnetic field is applied.

Then, it cools rapidly within 5 minutes to 500 degrees C or less. By doing so, the coarsening of the composite Fe phase and Sm ₅ Fe ₁₇ phase can be suppressed, and the fine and highly crystalline Fe phase (soft magnetic phase 11) and Sm ₅ Fe ₁₇ phase (hard magnetic phase 12) Thus, a magnetic material 10 having a composite structure can be obtained. Examples of the cooling rate include 20 ° C./min or more, and further 60 ° C./min. Cooling time t ₃ until the 500 ° C. or less is not particularly limited if it is within 5 minutes. If it becomes 500 degrees C or less, the cooling rate after that will not be ask | required in particular.

Rapid thermal process is cooled to room temperature after the magnetic field annealing process may be a high temperature T _2, and then re-heated from room temperature. Even in such a case, it is essential to raise the temperature from room temperature and then rapidly raise the temperature to T ₂ after reaching temperature T ₁ ⇒ hold the high temperature in a short time ⇒ rapid cooling. As described above, it is more efficient to perform the rapid heat treatment step continuously after the magnetic field heat treatment step.

[Magnetic material]
The magnetic material 10 obtained by the magnetic material manufacturing method described above includes a soft magnetic phase 11 made of Fe phase and a hard magnetic phase 12 made of Sm ₅ Fe ₁₇ phase, as shown in the right enlarged view of FIG. Containing a crystalline phase comprising The Fe phase is, for example, an α-Fe phase. The hard magnetic phase 12 is a crystal grain of the Sm ₅ Fe ₁₇ phase. In FIG. 1, the soft magnetic phase 11 is hatched to clarify the distinction between the soft magnetic phase 11 and the hard magnetic phase 12.

The magnetic material 10 has a composite structure (composite structure) containing a soft magnetic phase 11 composed of an Fe phase and a hard magnetic phase 12 composed of an Sm ₅ Fe ₁₇ phase as crystal phases. Since it is a composite structure in which an Fe phase having a high magnetization (soft magnetic phase 11) and an Sm ₅ Fe ₁₇ phase having a high coercive force (hard magnetic phase 12) are mixed, both of them are exchanged due to exchange interaction between the two phases. The phases can be exchange-coupled to have magnetic characteristics having both high magnetization and high coercive force, and magnetic characteristics can be improved.

  In particular, the magnetic material 10 preferably has a nano-sized soft magnetic phase 11 and a hard magnetic phase 12 and has a nanocomposite structure of the soft magnetic phase 11 and the hard magnetic phase 12. By having a nanocomposite structure, a strong exchange interaction works between the soft magnetic phase and the hard magnetic phase, and both the high-magnetization and high coercive force can be achieved by the exchange coupling of both phases, thereby further improving the magnetic properties. . “Nanosize” means that the average crystal grain size (crystal grain size) is 300 nm or less, more preferably 150 nm or less, and particularly 100 nm. The average crystal grain size (crystal grain size) of the magnetic phase in the magnetic material 10 can be obtained from the half-value width of the diffraction peak by X-ray diffraction (XRD) using the Scherrer equation. Examples of the nanocomposite structure include a form having a periodic structure in which soft magnetic phases and hard magnetic phases are alternately arranged in layers, and a form having a dispersed structure in which granular soft magnetic phases are dispersed in the hard magnetic phase. As the texture structure of the magnetic material, it is considered that the periodic structure is preferable to the magnetic characteristics because the periodic interval of the hard magnetic phase is smaller than the dispersed structure.

When the magnetic material 10 is a magnet, nitriding treatment is performed. In the nitriding treatment, heat treatment is performed on the magnetic material at a temperature equal to or higher than the nitriding temperature in an atmosphere containing nitrogen. The nitriding temperature is set to a temperature at which the Sm ₅ Fe ₁₇ phase of the crystal phase is nitrided to generate the Sm ₅ Fe ₁₇ N _x (X = 0.5 to 3) phase. The nitriding temperature is, for example, 300 ° C. or more and 500 ° C. or less. By setting the heating temperature to 300 ° C. or higher, nitriding can be promoted and an Sm ₅ Fe ₁₇ N _x (X = 0.5 to 3) phase can be easily formed. On the other hand, by setting the heating temperature to 500 ° C. or less, it is possible to suppress coarsening of the Fe phase and to suppress excessive nitridation and decomposition of Sm ₅ Fe ₁₇ N _x .

<Test example>
Magnetic materials (sample Nos. 1 to 20) were prepared by the following preparation process ⇒ magnetic field heat treatment process ⇒ rapid heat treatment process, and the magnetic properties of the obtained magnetic material and average crystal grains of the Fe phase (α-Fe phase) The diameter was examined. In addition, as a comparative example, a magnetic material (sample Nos. 21 to 33) was prepared by a procedure of preparation step ⇒ rapid heat treatment step without performing a magnetic field heat treatment step, and the magnetic properties and Fe phase (α− The average crystal grain size of (Fe phase) was examined.

In the preparation step, a raw material Sm—Fe alloy is prepared. A melt of an alloy containing 13% by mass of Sm and having the balance of Fe and inevitable impurities is quenched by a melt span method (cooling rate of 5 × 10 ⁵ ° C./second or more), and a quenched ribbon having a thickness of about 10 μm. The Sm—Fe-based alloy was prepared. This Sm—Fe based alloy is an amorphous alloy.

In the magnetic field heat treatment step, heat treatment was performed on the Sm—Fe-based alloy at a temperature T ₁ shown in Tables 1 and 2 while applying a magnetic field shown in Tables 1 and 2 in an argon atmosphere. Retention time of the heating temperatures T ₁ was 3 hours. Sample No. In 21-33, this process was not performed.

The rapid thermal process, continuous heat treatment at a heating temperature T _1, the temperature was raised to within 5 minutes temperature T ₂ shown in Table 1 and Table 2, the retention time indicated by the temperature T ₂ in Table 1 and Table 2 And cooled to 500 ° C. or lower within 5 minutes. Sample No. In 21 to 33, and the temperature was raised within 5 minutes from room temperature to the temperature _{T 2.} As described above, the sample Nos. Shown in Tables 1 and 2 were used. 1-No. 33 magnetic materials were produced.

  Sample No. 1-No. The magnetic properties of 33 magnetic materials were evaluated. Specifically, residual magnetization (T) and coercive force (kA / m) were measured using a vibration sample type magnetometer (VSM-5SC-5HF type manufactured by Toei Kogyo Co., Ltd.). Tables 1 and 2 show the remanent magnetization and coercive force of each sample.

  Sample No. 1-No. For 33 magnetic materials, the crystal phase was analyzed using an XRD apparatus (SmartLab, manufactured by Rigaku Corporation), and the average of the Fe phase (α-Fe phase) was calculated using the Scherrer formula from the half-value width of the diffraction peak by XRD. The crystal grain size (crystal grain size) was determined. Tables 1 and 2 show the average crystal grain size of the Fe phase of each sample.

From the results of crystal phase analysis by XRD, heat treatment from 250 ° C. to 350 ° C. while applying a magnetic field of 2T or more and 4T or less ⇒Raise the temperature rapidly from 600 ° C. to 800 ° C.⇒Hold for 2 minutes or more and 10 minutes or less⇒500 ° C. Sample No. which was rapidly cooled to below 1 to 9 can confirm the presence of the Fe phase and the Sm ₅ Fe ₁₇ phase as crystal phases, and a structure in which the Fe phase (soft magnetic phase) and the Sm ₅ Fe ₁₇ phase (hard magnetic phase) coexist (composite structure). It was. On the other hand, Sample No. with a small magnetic field in the magnetic field heat treatment. 12, 13 and sample Nos. 1 and 2 that do not undergo magnetic field heat treatment and have a low heating temperature in rapid heat treatment. No. 21 was not a nanocomposite structure.

Sample No. 1 to 9 had a residual magnetization of 0.72 T or more and a coercive force of 1000 kA / m or more. On the other hand, Sample No. with a low heating temperature of the magnetic field heat treatment. 10. Sample No. with high heating temperature of magnetic field heat treatment 11, Sample Nos. 12, 13 with small applied magnetic field of magnetic field heat treatment, Sample No. 12, with large applied magnetic field of magnetic field heat treatment. 14, 15 and sample No. 1 with a short holding time for rapid thermal processing. 16. Sample No. No. 16 having a long holding time for rapid thermal processing 17, 18 and sample No. with low heating temperature of rapid thermal processing. 19, Sample No. with high heating temperature of rapid thermal processing 20, sample no. 21 to 33 had a low residual magnetization of less than 0.70 T and a coercive force of less than 950 kA / m. This is probably because the fine and highly crystalline Fe phase and Sm ₅ Fe ₁₇ phase could not be sufficiently precipitated. Sample No. Nos. 1 to 9 have a composite structure in which the Fe phase and the Sm ₅ Fe ₁₇ phase are mixed, so that the residual magnetization can be improved by the Fe phase and the coercive force can be improved by the Sm ₅ Fe ₁₇ phase. .

Sample No. In Nos. 1 to 9, the average crystal grain size of the Fe phase was 150 nm or less, and the average crystal grain size of the Sm ₅ Fe ₁₇ phase was 120 nm or less. In particular, sample no. In Nos. 1 to 8, the average crystal grain size of the Fe phase was 100 nm or less, and a finer structure was obtained. This is probably because the heating temperature in the magnetic field heat treatment is low, the magnetic field is small, and the heating temperature in the rapid heat treatment is low, so that coarsening of the Fe phase is further suppressed. On the other hand, in the case of performing the two-stage heat treatment from magnetic field heat treatment to rapid heat treatment, the sample No. 14, 15 and sample No. with high heating temperature in rapid thermal processing. 20, Sample No. with a long holding time in rapid thermal processing. 17 and 18, the average crystal grain size of the Fe phase was coarsened to be over 150 nm. In the case of performing the two-stage heat treatment from magnetic field heat treatment to rapid heat treatment, the sample No. 10, Sample No. with a short holding time in rapid thermal processing. 16, Sample No. with low heating temperature in rapid heat treatment 19, the average grain size of the Fe phase is as small as less than 100 nm, but the remanent magnetization is small because the Fe phase is not sufficiently precipitated and crystallized, and the coercive force is small because the Sm ₅ Fe ₁₇ phase is not generated. It is thought.

  The magnetic material manufacturing method of the present invention is preferably used for manufacturing raw materials and materials for permanent magnets used in various motors, particularly high-speed motors used in hybrid vehicles (HEV) and hard disk drives (HDD). Can do.

10 Magnetic material 11 Soft magnetic phase (Fe phase)
12 Hard magnetic phase (Sm ₅ Fe ₁₇ phase)
20 SM-Fe alloy powder 30 Quenched ribbon

Claims (2)

A preparation step of preparing an Sm-Fe-based alloy containing Sm and Fe;
A magnetic field heat treatment step in which heat treatment is performed at a temperature of 250 ° C. or higher and 350 ° C. or lower while applying a magnetic field of 2T or higher and 4T or lower to the Sm—Fe-based alloy in an atmosphere that does not react with Sm and Fe or in a reduced pressure atmosphere;
After the magnetic field heat treatment step, the Sm—Fe alloy is rapidly increased within 5 minutes from the heating temperature in the magnetic field heat treatment step to 600 ° C. to 800 ° C. in an atmosphere that does not react with Sm and Fe or in a reduced pressure atmosphere. And a rapid heat treatment step of performing a heat treatment of holding the temperature for 2 minutes to 10 minutes and then rapidly cooling to 500 ° C. or less within 5 minutes.   The method for producing a magnetic material according to claim 1, wherein the Sm—Fe-based alloy in the preparation step is in an amorphous state, and the Sm content is 10% by mass or more and 45% by mass or less.

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