JP2023132665A - Fcc magnet, fcc magnet manufacturing method, fcc composite magnet, and method for adjusting magnetic properties of fcc magnet - Google Patents

Abstract

To provide FCC magnets with various magnetic properties.SOLUTION: An FCC magnet has a density of 3.0 to 7.1 g/cm3, preferably has a void, and preferably has a residual magnetic flux density Br of 0.5 to 1.3T. The FCC magnet is obtained by producing a shaped body having a void portion using an additive manufacturing method and heat-treating the shaped body to obtain the FCC magnet according to claim 1, and the energy density in the additive manufacturing method is preferably 50 to 95 J/mm3.SELECTED DRAWING: Figure 5

Description

The present invention relates to an FCC magnet, a method for manufacturing an FCC magnet, an FCC composite magnet, and a method for adjusting magnetic properties of an FCC magnet.

Magnetic materials are classified into hard magnetic materials and soft magnetic materials. Among these, hard magnetic materials refer to magnetic materials that have a large coercive force and are difficult to demagnetize in response to external magnetic fields. Typical examples include permanent magnets such as ferrite magnets, NdFeB magnets, SmCo magnets, and metal magnets. be. Among these, metal magnets have the advantage of being excellent in corrosion resistance and suitable for mass production of relatively small items and complex shapes. Examples of metal magnets with such advantages include magnets whose main components are iron, chromium, and cobalt (iron-chromium-cobalt alloy magnets, hereinafter referred to as FCC magnets), and magnets containing iron, aluminum, nickel, and cobalt. There is a magnet (hereinafter referred to as an alnico magnet) as a main component.

Compared to alnico magnets, FCC magnets have higher residual magnetic flux density and maximum energy product, so they have excellent magnetic performance.Furthermore, because they contain less cobalt, they can reduce the risk of price fluctuations. In addition, like alnico magnets, FCC magnets have a small temperature coefficient of residual magnetic flux density, so they have excellent temperature stability, and because they do not use rare earths as raw materials, they have excellent procurement stability and are easy to apply to products. be. Note that FCC magnets are used in stepping motors, relays, torque limiters, magnetic sensors, etc.

FCC magnets can be manufactured by melting a metal material containing Fe, Cr, and Co, solidifying it by cooling, and then performing a heat treatment process such as solution treatment, heat treatment in a magnetic field, and aging treatment. These heat treatment steps cause spinodal decomposition in the Fe--Cr--Co alloy, and single-domain fine particles of the ferromagnetic phase are precipitated in the non-magnetic matrix. When spinodal decomposition occurs, magnetic anisotropy can be imparted to the Fe-Cr-Co alloy by applying a magnetic field in a specific direction. Conventional FCC magnets are manufactured by casting or rolling methods.

In addition, as a manufacturing method for FCC magnets other than the casting method or the rolling method, Patent Document 1 and Non-Patent Document 1 disclose that an additive manufacturing method (three-dimensional additive manufacturing method) is used using an iron-chromium-cobalt alloy material. It has been shown that an iron-chromium-cobalt laminated alloy can be obtained which can contribute to reducing cracking and chipping during processing.

JP2021-42456A Japanese Patent Application Publication No. 7-201623 International Publication No. 2007/135981

Onuma, et al.: Application of metal additive manufacturing method in production of iron-chromium-cobalt magnets, Hitachi Metals Technical Report, vol. 37, p54-61

Although FCC magnets have a high residual magnetic flux density B _r , the B _r is limited to about 1.3 to 1.4 T for anisotropic and around 0.9 T for isotropic, and 1 to 1 in between. It is thought that an FCC magnet with a _Br of about .2T has not been put into practical use. If it is desired to obtain a magnet with desired magnetic properties using an FCC magnet, it is conceivable to adjust the magnet composition and consider the conditions of the heat treatment process accordingly. However, desired magnetic properties cannot be uniquely obtained by adjusting them, and many hurdles are expected before an FCC magnet with such magnetic properties can be obtained and put into practical use.

Therefore, an object of the present invention is to provide FCC magnets having various magnetic properties.

As for the technique of reducing the density of magnets, attempts have been made to manufacture NdFeB-based magnets having voids. For example, Patent Document 2 discloses a low-density sintered magnet, and Patent Document 3 discloses a porous magnet produced by the HDDR method. By forming both structures with voids, the purpose is to suppress shrinkage during sintering, and the purpose is not to adjust magnetic properties. Regarding FCC magnets manufactured by casting or rolling methods, no attempt has been made to adjust the magnetic properties by lowering the density.

The inventors used an additive manufacturing method to fabricate FCC magnet shapes with various densities lower than that of conventional FCC magnets, and by heat-treating them, they easily produced FCC magnets with various magnetic properties. For example, it has been found that an FCC magnet having a coercive force H _cB of around 50 kA/m and a residual magnetic flux density B _r lower than 1.3 T can be obtained.

The FCC magnet in an embodiment of the present invention is characterized by a density of 3.0 to 7.1 g/cm ³ .

Preferably, the FCC magnet has a gap.

The residual magnetic flux density B _r of the FCC magnet is preferably 0.5 to 1.3T.

In an embodiment of the present invention, a method for manufacturing an FCC magnet body uses an additive manufacturing method to produce a shaped body having voids, and heat-treats the shaped body to achieve a density of 3.0 to 7.1 g/cm ³ . The present invention is characterized in that an FCC magnet body is obtained.

The energy density in the additive manufacturing method is preferably 50 to 95 J/mm ³ .

The FCC magnet body in another embodiment of the invention is characterized by a density of 6.0 to 7.1 g/cm ³ .

Preferably, the FCC magnet body does not have any voids designed as a modeling drawing.

The residual magnetic flux density B _r of the FCC magnet is preferably 1.0 to 1.3T.

In another embodiment of the present invention, a method for manufacturing an FCC magnet body uses an additive manufacturing method to produce shaped bodies with an energy density of 20 to 45 J/mm ³ , and heat-treats them to have a density of 6.0 J/mm 3 . The present invention is characterized by obtaining an FCC magnet body having a weight of ~7.1 g/cm ³ .

The FCC composite magnet in an embodiment of the present invention has at least a low-density part having a void and a density of 3.0 to 7.1 g/cm ³ or less, and a high-density part having a density of more than 7.1 g/cm ³ . It is characterized by having a density part.

The FCC composite magnet according to another embodiment of the present invention has at least a low-density portion that does not have any voids and has a density of 6.0 to 7.1 g/cm 3 or less as designed as a modeling drawing, and a low-density portion that has a density of 7.0 g/cm ³ or less. It is characterized by having a high density portion exceeding .1 g/cm ³ .

Preferably, the FCC composite magnet has a structure in which the high-density portion and the low-density portion change periodically.

A method for adjusting the magnetic properties of an FCC magnet according to an embodiment of the present invention includes manufacturing an FCC alloy shaped body having a void and a density of 3.0 to 7.0 g/cm ³ using an additive manufacturing method, and heat-treating the shaped body. Accordingly, the residual magnetic flux density B _r of the FCC magnet body is set to 0.5 to 1.3T.

A method for adjusting the magnetic properties of an FCC magnet according to another embodiment of the present invention is to manufacture an FCC alloy shaped body having a density of 6.0 to 7.0 g/cm ³ using an additive manufacturing method, and heat-treat the body. , the residual magnetic flux density B _r of the FCC magnet is 1.0 to 1.3T.

According to the present invention, FCC magnets having various magnetic properties can be provided.
For example, it is possible to provide an FCC magnet with a coercive force H _cB of around 50 kA/m and a residual magnetic flux density B _r lower than 1.3 T, which has not been easily available in the past.
Furthermore, an FCC magnet can be provided that is less dense than conventional FCC magnets, ie, lighter than conventional FCC magnets.

It is a photograph of a shaped object in an example of the present invention. It is a graph showing the relationship between the density and magnetic properties of an FCC magnet body in an example of the present invention. It is a figure showing the composition of the test piece in the example of the present invention. 4 is a photograph of a test piece in an example of the present invention viewed from the Z direction in FIG. 3. 4 is a photograph of a test piece in an example of the present invention viewed from the Y direction in FIG. 3.

First, the FCC magnet will be explained in detail. FCC magnets can be manufactured by melting a metal material containing Fe, Cr, and Co, solidifying it by cooling, and then performing a heat treatment process such as solution treatment, heat treatment in a magnetic field, and aging treatment. These heat treatment steps cause spinodal decomposition in the Fe--Cr--Co alloy, and single-domain fine particles of the ferromagnetic phase are precipitated in the non-magnetic matrix. When spinodal decomposition occurs, magnetic anisotropy can be imparted to the Fe-Cr-Co alloy by applying a magnetic field in a specific direction. Conventional FCC magnets are manufactured by casting or rolling methods. Details of the casting method and rolling method are omitted in this specification.

Hereinafter, the Fe-Cr-Co alloy before the heat treatment process will be simply referred to as "FCC alloy" to distinguish it from the "FCC magnet" after the heat treatment process. Further, in this specification, an FCC alloy shaped by the additive manufacturing method is referred to as an "FCC alloy shaped body" or simply a "shaped body", and an FCC magnet obtained by heat-treating the FCC alloy shaped body is referred to as an "FCC magnet body". It is called. Further, the FCC alloy shaped body and the FCC magnet body include those that have been subjected to cutting, cutting, etc. Further, an FCC magnet body having partially different densities, which will be described later, will be referred to as an FCC composite magnet body.

Further, in this specification, "density" refers to "apparent density" including voids in the alloy and magnet. The density of the FCC magnet is calculated as (mass/volume of external shape) of the FCC magnet, and is distinguished from the partial magnet density inside the FCC magnet. Furthermore, the term "void" in the present invention refers to a void designed as a modeling drawing, such as a minute void that is normally included in an alloy or a magnet, or a molded object formed by changing the additive manufacturing conditions described below. It is distinguished from minute voids that may be created by reducing the density of On the other hand, in the present invention, "having no voids designed as a modeling drawing" refers to voids designed as a modeling drawing, that is, open voids designed as a modeling drawing (3D CAD data) as described below. This means that there are no closed voids, including microscopic voids that are normally included in alloys and magnets, and microscopic voids that may occur when the density of the modeled object is reduced by changing the additive manufacturing conditions described below. It is assumed that there may be voids.

The FCC magnet of the present invention can be manufactured by an additive manufacturing method (specifically, sometimes referred to as an additive manufacturing method or a three-dimensional additive manufacturing method). Unlike subtractive processing through cutting or molding processing where material is poured into a mold and hardened, additive manufacturing methods can easily and accurately produce shapes that were previously difficult to manufacture, such as mesh shapes and porous shapes. Can be manufactured. There are various methods of additive manufacturing, but for example, in the powder bed fusion additive manufacturing method, powder material is spread layer by layer over the entire printing stage, and each layer is irradiated with a laser at a predetermined location corresponding to the 3D CAD data. etc., to melt and solidify the powder materials and integrate them. By repeating this process, the desired shaped object can be obtained. In the additive manufacturing method, not only resin but also metal can be used as the material. In Patent Document 1 and Japanese Patent Application No. 2021-019881, the applicant discloses a method of manufacturing an FCC alloy and an FCC magnet using a powder bed fusion additive manufacturing method as a representative example.

Hereinafter, a method for manufacturing an FCC magnet using an additive manufacturing method will be described in detail.

[Raw material powder]
In the present invention, a powdered FCC alloy is used as a raw material. More specifically, it is an FCC alloy consisting of 17 to 45% Cr, 3 to 35% Co, 5% or less of additional elements, and the remainder is Fe and unavoidable impurities, and the additional elements include, for example, Ti, Mo, etc. , V, Si, and Al. It is preferable that the additive element contains at least Ti, and for example, the composition may be made of 17 to 45% Cr, 3 to 35% Co, 0.1 to 5% Ti, and the balance is Fe and unavoidable impurities in terms of mass ratio. More preferably, the composition is 20 to 40% Cr, 5 to 14% Co, 0.1 to 0.6% Ti, and the balance is Fe and unavoidable impurities. It is also possible to contain elements other than Ti in combination. In order to obtain an FCC alloy with the desired composition, a predetermined amount of feed materials for each element are weighed and mixed. The raw materials are loaded into a crucible, melted by high frequency, and the molten alloy is dropped from a nozzle under the crucible and heated under high pressure. A gas atomized powder is produced by atomizing with argon. The FCC alloy powder obtained by classifying this gas atomized powder is used as the raw material powder for the additive manufacturing method.

[Additive manufacturing]
In producing a shaped body of FCC alloy, first, three-dimensional CAD data in which the shaped body is divided into layers is created. Next, using a powder bed fusion type additive manufacturing machine, the raw material powder supplied onto the base plate in each divided layer is rapidly melted and rapidly solidified by laser irradiation, and then layered to form a three-dimensional model on the base plate. Create a body. Finally, the FCC alloy shaped body is obtained by separating the shaped body from the base plate.

There are two main methods for producing shaped bodies of various densities. One method is to create a modeling drawing with voids using 3D CAD data and thereby create a modeled object with voids, and the other method is to change the additive manufacturing conditions to apply energy to the powder. This is a method of lowering the density of a shaped object by lowering the density and creating an unfused state in the powder.

Since there is almost no change in the density of the shaped body produced by the additive manufacturing method and the density of the FCC magnet body after heat treatment, in the present invention, a shaped body of FCC alloy with a density of 3.0 to 7.1 g/cm ³ is used. Create. The true density of an FCC magnet is about 7.7 g/cm ³ , and the density of conventional FCC magnets currently on the market and FCC magnets manufactured by the additive manufacturing method described in Patent Document 1 is close to the true density, and is 7.5 to 7.6 g/cm 3 . ^cm3 , and the density of the FCC magnet of the present invention is lower than these.

Here, the additive manufacturing conditions are appropriately determined in consideration of the particle size and composition of the raw material powder, the size, shape, and characteristics of the molded object, production efficiency, and the like. Regarding the FCC alloy of the present invention, the energy density (heat source energy density: J/mm ³ ) input by laser irradiation in order to melt the raw material powder at high speed is in the range of 20 to 95 J/mm ³ and the method described below is used. , a shaped body with a density of 3.0 to 7.1 g/cm ³ can be produced. If the energy density is less than 20 J/mm ³ , the strength of the shaped body will be low and it will be difficult to put it to practical use as a magnet. On the other hand, if the energy density is too high, the raw material powder will melt over a wide range around the laser irradiation position, making it difficult to maintain the shape of the shaped object. In consideration of magnetic properties, particularly a decrease in squareness ratio and an increase in defect rate, the energy density is more preferably in the range of 35 J/mm ³ or more and 70 J/mm ³ or less. Furthermore, in order to achieve such an energy density, it is preferable that the thickness of each raw material powder layer during additive manufacturing is 10 to 80 μm. The laser irradiation beam diameter is preferably about 0.1 mm. The laser output is preferably 50 to 400W. The laser scanning speed is preferably 400 to 2500 mm/s. The laser scanning pitch is preferably 0.04 to 0.15 mm. Here, the energy density E (J/ ^mm3 ) is determined by the laser output P (W), the laser scanning speed v (mm/s), the laser scanning pitch a (mm), and the layer thickness d (mm) of the raw material powder layer. It is obtained from equation (1) using

E=P/(v×a×d) (1)

[Method of producing a shaped object having a void]
Methods for designing a void as a modeling drawing (three-dimensional CAD data) include a method for designing an open void and a method for designing a closed void.

The method of designing an open void is a design in which the surface of the modeled object and the surface of the void are continuous, that is, the void is not independent from the inside but communicates with the outside, and powder does not remain inside the model after the object is removed. It's a method. Thereby, the density of the shaped body can be reduced.

In addition, the method of designing a closed cavity means that the surface of the modeled object and the surface of the cavity are not continuous, that is, the cavity is independent inside and does not communicate with the outside, and after the object is taken out, the powder is This is a design method that allows it to remain inside the body. This method also allows the density of the shaped body to be reduced.

In either case, the shape and arrangement of the voids may be arbitrary. For example, in the example described later, a plurality of through holes with a uniform diameter are provided in the test piece, but the shape of the holes is not limited to circular, but can be irregular, the diameter does not have to be uniform, and the holes do not have to be penetrating. It's okay. A three-dimensional lattice shape or a mesh shape may also be used.

In this case, the additive manufacturing conditions are such that the energy density is preferably in the range of 50 to 95 J/mm ³ , more preferably 60 to 80 J/mm ³ . As a result, the density of the shaped body in parts other than the voids is equal to that of conventional FCC alloys, and the average density of the entire shaped body including the voids is 3.0 to 7.1 g/cm ³ . Further, as described later, the density of the shaped body may be adjusted by changing the energy density within the above range.

According to the method of producing a shaped body having a void, the density of the alloy in the portion other than the void is equivalent to the density of a conventional FCC alloy, so only the residual magnetic flux density B _r is lower than that of a conventional FCC magnet. This makes it possible to suppress a decrease in coercive force _HcB and squareness ratio _Hk as much as possible.

[Method of reducing the density of the modeled object by changing the additive manufacturing conditions]
In this method, by changing the energy density of the additive manufacturing conditions, the density of the shaped body can be changed by lowering the energy density applied to the powder and creating an unmolten state in the powder. The energy density E (J/mm ³ ) is expressed as E=P/(v×a×d) as described above, and the energy density can be changed by lowering the laser output P, increasing the speed v, etc. .

In this case, by changing the energy density in the range of 25 to 45 J/mm ³ , the density of the shaped body can be set to 6.0 to 7.1 g/cm ³ . Considering the strength of the shaped body, the reduction in squareness ratio, etc., it is preferable to vary the energy density in the range of 30 to 45 J/mm ³ and set the density of the shaped body to 6.5 to 7.1 g/cm ³ . .

According to the method of changing the additive manufacturing conditions, the molded object does not have a void designed as a molding drawing inside. However, the above method of changing the layered manufacturing conditions to reduce the density of the molded object and the method of designing the above-mentioned void portion as a molding drawing may be combined. That is, as mentioned above, the additive manufacturing conditions when molding a shaped body having voids may be varied within the energy density range of 50 to 95 J/mm ³ to form shaped bodies with various densities. .

[Heat treatment]
After modeling, the shaped body is subjected to solution treatment, heat treatment in a magnetic field, and aging treatment.

The solution treatment is performed in a vacuum or reduced pressure atmosphere, or in an oxidizing atmosphere (typically in the air), at a temperature of 600°C or more and 950°C or less, preferably 700°C or more and 850°C or less, for example, 10 Maintain for at least 20 minutes. Through this solution treatment, the FCC alloy becomes a state composed of a solid solution (α phase) of a ferromagnetic element and a nonmagnetic element.

The heat treatment in a magnetic field is performed by maintaining the temperature of the shaped object in a magnetic field of 200 kA/m or higher, for example, in a range of 600° C. or higher and 700° C. or lower, preferably 620° C. or higher and 660° C. or lower, for example, for 60 minutes or more and 90 minutes or less. . By this heat treatment in a magnetic field, spinodal decomposition progresses in the FCC alloy, and the alloy changes into a state where it is separated into two phases: α1 phase (FeCo ferromagnetic phase) and α2 phase (Cr nonmagnetic phase). Since a magnetic field is applied when spinodal decomposition progresses, the ferromagnetic α1 phase grows long in alignment with the direction of the magnetic field. As a result, shape magnetic anisotropy can be developed. The atmosphere for the magnetic field heat treatment may also be air.

The aging treatment is performed at a temperature range of 400°C or higher and 670°C or lower. In the aging treatment, the aging treatment is performed at 1 to 7 degrees Celsius per hour, preferably from an aging treatment start temperature (for example, 570 to 670 degrees Celsius) that is about 5 to 30 degrees Celsius lower than the temperature of the heat treatment in a magnetic field, to an aging treatment end temperature (for example, 400 to 600 degrees Celsius). Preferably, a controlled cooling process is included at a rate of temperature drop of 2 to 6° C. per hour. The temperature may be lowered from the temperature of heat treatment in a magnetic field to below the aging treatment start temperature. In that case, cooling is started after the temperature is raised to the aging treatment start temperature. This increases the compositional difference between the α1 phase and α2 phase, allowing them to be separated into a FeCo-rich phase and a Cr-rich phase, making it possible to grow the α1 phase more in the direction of the magnetic field and increase the coercive force. It becomes possible. The atmosphere for the aging treatment may also be air.

As mentioned above, the magnet density is almost unchanged before and after heat treatment, and by the above method, an FCC magnet body with a density of 3.0 to 7.1 g/cm ³ can be produced. Although it depends on the magnet composition, the magnetic properties after heat treatment are such that the coercive force H _cB is maintained at about 48 to 50 kA/m, and the residual magnetic flux density B _r is about 0.5 to 1.3 T. FCC magnet bodies with various magnetic properties can be produced without adjusting heat treatment conditions to various conditions.

[FCC composite magnet]
According to the additive manufacturing method, FCC composite magnets with partially different densities can be created by changing the energy density during lamination or by modeling using CAD data that combines parts with and without voids. is possible. For example, according to a method of changing energy density during lamination, there is at least a low-density portion with a density of 6.0 to 7.1 g/cm ³ and a high-density portion with a density of more than 7.1 g/cm ³ An FCC composite magnet can be obtained. Furthermore, according to the method of combining parts with and without voids, at least a low-density part with voids and a density of 3.0 to 7.1 g/cm ³ and a density of 7.1 g/cm ³ It is possible to obtain an FCC composite magnet having a high-density portion exceeding . Furthermore, it is possible to produce an FCC composite magnet having a structure in which these high-density portions and low-density portions change periodically. Such an FCC composite magnet can be expected to be applied to, for example, a magnetic scale of an encoder.

In Example 1, test pieces with different densities were produced by changing the laser irradiation conditions to produce shaped test pieces with different energy densities.

A predetermined amount of the feed material of each element was weighed so that the composition was 10.1% Co, 24.5% Cr, 0.2% Ti, 0.5% C, and the balance Fe in mass%. The mixed raw materials were loaded into a crucible, subjected to high frequency melting in a vacuum, and the molten alloy was dropped from a 5 mm diameter nozzle under the crucible and sprayed with high pressure argon to produce gas atomized powder. This gas atomized powder was classified to obtain FCC alloy powder of 10 to 60 μm. This was used as a raw material powder.

Using a powder bed fusion type three-dimensional additive manufacturing machine (EOS-M290 manufactured by EOS), the raw material powder supplied onto the S45C base plate is rapidly melted and rapidly solidified by laser irradiation, and the laser output (W) and energy density are determined. J/mm ³ is shown in Table 1, other conditions are: Thickness of raw material powder layer/0.04mm
・Laser beam diameter/approx. 0.1mm
・Laser scanning speed/800mm/s
・Scanning pitch/0.09mm
A shaped body having a side of approximately 10 mm was produced under the following additive manufacturing conditions.

As for the heat treatment of the shaped body, first, solution treatment was performed at 900°C for 1.3 hours, then in a magnetic field of 260 kA/m, 620°C for 2.5 hours, and further aging treatment was performed at 625°C for 1.2 hours. . Thereafter, it was cooled at a rate of about 5° C./min.

[Magnetic properties]
After magnetization, the magnetic properties of the shaped body were evaluated using a BH tracer. The BH curve of each shaped body was determined, and the results were as shown in Table 1 from the BH curve. Note that the densities in Table 1 were determined from the exact dimensions and weight of the shaped bodies after heat treatment.

As shown in Table 1, when the energy density was less than 25 J/mm ³ , there were conditions in which the molded object collapsed during modeling and the molded object could not be formed (Nos. 1-1 and 1-3). Furthermore, No. No. 1-2 had low squareness (H _k =14.1 kA/m), a value that made it difficult to put it to practical use as an anisotropic FCC magnet (the above are comparative examples). When the energy density is 25 to 42 J/cm ³ , the printing results are good, B _r can be lowered to 1 T, and other magnetic properties have no practical problems, and when the density is 6.0 to 7.1 g/cm ³ . It was confirmed that FCC magnets with magnetic properties that could not be easily obtained in the past were obtained (Nos. 1-4 to 8, Examples). Further, when the energy density was 45 J/mm ³ or more, the modeling results were good, but the density and magnetic properties were not much different from conventional FCC magnets (reference example).

In Example 2, modeling drawings (three-dimensional CAD data) with different hole diameters in the void portion are created as shown in Figure 1, and penetrating holes with different diameters are formed inside the shaped object test piece as shown in Table 2. Test specimens with three different densities (average densities) were prepared. Table 2 shows, in addition to the hole diameter, the volume ratio of the void portion calculated from the hole diameter, and the density determined from the exact dimensions and weight of the shaped body after heat treatment. In Example 2, the laser output was 200 W, the energy density was 69.4 J/mm ³ , and other modeling conditions were the same as in Example 1. After modeling, heat treatment and evaluation of magnetic properties were performed in the same manner as in Example 1.

As shown in FIG. 1 and Table 2, test pieces with different densities (average densities) could be produced by designing the voids as modeling drawings (three-dimensional CAD data). All of the molding results were good, and it was found that the magnetic properties could be reduced to around 0.5T with almost no decrease in coercive force or _squareness .

FIG. 2 is a graph showing the relationship between magnet density and _Br in Examples 1 and 2. In both Examples 1 and 2, there is a correlation between magnet density and B _r , but the slope is gentler in Example 2. As can be seen in the comparison, it was confirmed that an FCC magnet body with a higher _Br could be produced with the same density. Furthermore, as seen in the comparison between Examples 1-4 and 1-5 and Example 2-2, it was confirmed that a lower density (lighter) FCC magnet can be produced with the same amount of _Br . Furthermore, in Example 2, it is possible to print to a lower density than in Example 1, and by adjusting the size of the void, the density is 3.0 to 7.1 g/cm ³ and B _r is 0.5 to 7.1 g/cm 3 . It was confirmed that a 1.3T FCC magnet could be produced.

In Example 3, as shown in FIG. 3, a test piece was prepared in which a low-density part 1 and a high-density part 2 of different densities were combined. For the test piece, first, a high-density part 1 having a dimension in the X direction of x2 was formed, and then a low-density part 2 and a high-density part 1 each having a dimension in the X direction of x3 were alternately formed in the direction of the arrow. The modeling conditions are shown in Table 3. The high-density portion 1 was molded under the same molding conditions as in Example 1-16, and the low-density portion 2 was molded by lowering the energy density or by providing a void under the same molding conditions as in Example 1-16. FIG. 4 is a photograph of the prepared test piece viewed from the Z direction of FIG. 3, and FIG. 5 is a photograph of the prepared test piece viewed from the Y direction of FIG.

Here, in order to accurately measure the density of each of the high-density part 1 and the low-density part 2, it is necessary to break the test piece and divide it into high-density part 1 and low-density part 2, and these densities cannot be measured. Although it is difficult, since the printing conditions for high-density part 1 are the same as those in Example 1-16, its density is around 7.55 g/ ^cm3 , and for low-density part 2, the printing conditions are the same as for high-density part 1. and has a hole, and the volume ratio of the void calculated from the hole diameter is between Examples 2-2 and 2-3 (density 3.68 to 5.70 g/cm ³ ), or Since the energy density of the modeling conditions is the same as in Example 1-4 (density 6.24 g/cm ³ ), their density is considered to be lower than that of high-density part 1, and high-density part 1 and low-density part 2 are It was confirmed that an FCC composite magnet with a periodically changing structure could be produced.

The present invention has industrial applicability in that, for example, an FCC magnet having a coercive force H _cB of around 50 kA/m and a residual magnetic flux density B _r lower than 1.3 T can be obtained.

1 High density part 2 Low density part

Claims (14)

An FCC magnet having a density of 3.0 to 7.1 g/cm ³ . The FCC magnet according to claim 1, characterized in that it has a cavity. The FCC magnet according to claim 1 or 2, wherein the residual magnetic flux density B _r is 0.5 to 1.3T. 2. A method for producing an FCC magnet, which comprises producing a shaped body having a void using an additive manufacturing method, and heat-treating the shaped body, thereby obtaining the FCC magnet according to claim 1. 5. The method for manufacturing an FCC magnet according to claim 4, wherein the energy density in the additive manufacturing method is 50 to 95 J/mm ³ . An FCC magnet having a density of 6.0 to 7.1 g/cm ³ . 7. The FCC magnet according to claim 6, characterized in that it does not have any voids designed as a modeling drawing. The FCC magnet according to claim 6, wherein the residual magnetic flux density B _r is 1.0 to 1.3T. Production of an FCC magnet body, characterized in that the FCC magnet body according to claim 6 is obtained by producing shaped bodies with an energy density of 20 to 45 J/mm ³ using an additive manufacturing method and heat-treating them. Method. FCC composite characterized by having at least a low-density part having voids and a density of 3.0 to 7.1 g/cm ³ or less, and a high-density part having a density of more than 7.1 g/cm ³ magnetic body. An FCC composite magnet having at least a low-density part with a density of 6.0 to 7.1 g/cm ³ or less and a high-density part with a density of more than 7.1 g/cm ³ . The FCC composite magnet according to claim 9 or 10, wherein the high-density portion and the low-density portion have a structure that changes periodically. By manufacturing an FCC alloy shaped body having a density of 3.0 to 7.0 g/cm ³ with voids using an additive manufacturing method and heat treating it, the residual magnetic flux density B _r of the FCC magnet body can be reduced to 0.5 to 7.0 g/cm 3 . A method for adjusting the magnetic properties of an FCC magnet, characterized by setting it to 1.3T. By manufacturing an FCC alloy shaped body with a density of 6.0 to 7.0 g/cm ³ using an additive manufacturing method and heat treating it, the residual magnetic flux density B _r of the FCC magnet body can be reduced to 1.0 to 1.3 T. A method for adjusting magnetic properties of an FCC magnet, characterized by: