KR102677932B1 - Rare earth magnet and its manufacturing method - Google Patents

Abstract

The present invention is a rare earth produced by discharge plasma sintering and then hot pressing magnetic powder containing 20 to 40% by weight of Re, 0.1 to 1.0% of B, 0.1 to 10% of M, and the balance being Fe and inevitable impurities. In the magnet, Re includes a rare earth element, M includes a metal, and the rare earth magnet has an orientation coefficient (f) defined by the following relational equation 1 exceeding 0.15.
[Relationship 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.)

Description

Rare earth magnet and its manufacturing method

The technical idea of the present invention is to discharge plasma sintered magnetic powder containing 20 to 40% by weight, 0.1 to 1.0% of B, 0.1 to 10% of M, and the balance of Fe and inevitable impurities, and then hot compress and orient the powder. It relates to a rare earth magnet with a coefficient (f) exceeding 0.15 and a method of manufacturing the same.

Rare earth magnets containing rare earth elements such as Nd, Ce, and Pr have excellent magnetic properties such as coercivity, magnetic flux density, and maximum magnetic energy, and are used in various electromagnetic devices. Recently, they have been included in motors and mechanical devices, so demand continues. is increasing.

For this reason, a number of prior documents, such as Republic of Korea Patent Publication No. 10-2014-0053326 and Republic of Korea Patent Publication No. 10-2022-0115773, describe rare earth magnets with improved magnetic properties and their manufacturing methods.

However, rare earth magnets have large changes in magnetic properties depending on the grain size, degree of refinement, and degree of anisotropy, making it difficult to optimize the magnetic properties. For this reason, a method for manufacturing rare earth magnets with fine grains and excellent anisotropy is required.

Republic of Korea Patent Publication No. 10-2014-0053326 (2014.05.07) Republic of Korea Patent Publication No. 10-2022-0115773 (2022.08.18) Republic of Korea Patent Publication No. 10-2015-0033423 (2015.04.01)

The technical problem to be achieved by the technical idea of the present invention is to provide a rare earth magnet with excellent anisotropy and suppressed coarsening of crystal grains by discharging and plasma sintering magnetic powder and then hot compressing the magnetic powder, and a method for manufacturing the same, in manufacturing a rare earth magnet. will be.

However, these tasks are illustrative, and the technical idea of the present invention is not limited thereto.

The present invention to achieve the above technical problem is to discharge plasma sintering a magnetic powder containing 20 to 40% by weight, 0.1 to 1.0% of B, 0.1 to 10% of M, and the balance of Fe and inevitable impurities, In the rare earth magnet manufactured by hot compression, Re includes a rare earth element, M includes a metal, and the rare earth magnet has an orientation coefficient (f) defined by the following relational equation 1 exceeding 0.15. .

[Relational Expression 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.)

In one embodiment of the present invention, Re includes one or more rare earth elements selected from Nd, Ce, and Pr, and M includes one or more metals selected from Co, Al, Cr, Cu, Ga, Ag, and Au. may include.

In one embodiment of the present invention, the crystal grains of the rare earth magnet may have an aspect ratio of 3 to 8.

In one embodiment of the present invention, the magnetic flux density may be 12.5 kG or more.

In one embodiment of the present invention, the maximum magnetic energy product may be 40 MGOe or more.

The present invention for achieving the above technical problem is preparing a magnetic powder containing 20 to 40% by weight, B 0.1 to 1.0%, M 0.1 to 10% and the balance Fe and inevitable impurities, the magnetic A step of manufacturing a rare earth sintered body by spark plasma sintering the powder and manufacturing a rare earth magnet by hot compressing the rare earth sintered body, wherein the rare earth magnet has an orientation coefficient (f) defined by the following relational equation 1: It relates to a method of manufacturing a rare earth magnet with a value exceeding 0.15.

[Relationship 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.)

In one embodiment of the present invention, Re includes one or more rare earth elements selected from Nd, Ce, and Pr, and M includes one or more metals selected from Co, Al, Cr, Cu, Ga, Ag, and Au. may include.

In one embodiment of the present invention, the discharge plasma sintering may be performed by pressing the magnetic powder at 30 to 70 MPa for 3 to 7 minutes at 600 to 800°C.

In one embodiment of the present invention, the hot compression may be performed by pressing the rare earth sintered body at 50 to 80 MPa for 8 to 15 minutes at 600 to 1,000°C.

The present invention is manufactured by discharge plasma sintering of magnetic powder containing 20 to 40% by weight, 0.1 to 1.0% of B, 0.1 to 10% of M, and the balance of Fe and inevitable impurities, and then hot pressing to produce crystal grains. Rare earth magnets with growth suppressed and anisotropy improved can be manufactured.

The effects of the present invention described above have been described as examples, and the scope of the present invention is not limited by these effects.

1 is a flowchart illustrating a method of manufacturing a rare earth magnet according to an embodiment of the present invention.
Figure 2 shows the results of XRD diffraction analysis of rare earth magnets manufactured according to Examples and Comparative Examples of the present invention.
Figure 3 is a graph comparing the crystallographic properties of rare earth magnets manufactured according to Examples and Comparative Examples of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments of the present invention are provided to more completely explain the technical idea of the present invention to those skilled in the art, and the following examples may be modified into various other forms, and the embodiments of the present invention may be modified. The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the technical idea of the present invention to those skilled in the art. In this specification, like symbols refer to like elements throughout. Furthermore, various elements and areas in the drawings are schematically drawn. Accordingly, the technical idea of the present invention is not limited by the relative sizes or spacing drawn in the attached drawings.

The present invention relates to a rare earth magnet, and more preferably, magnetic powder containing 20 to 40% by weight, B 0.1 to 1.0%, M 0.1 to 10% and the balance Fe and inevitable impurities is subjected to discharge plasma. It relates to a rare earth magnet manufactured by sintering and then hot pressing.

According to an embodiment, the Re may include a rare earth element, preferably one or more rare earth elements selected from Nd, Ce, and Pr, and even more preferably may include Nd.

According to an embodiment, M may include one or more metals selected from Co, Al, Cr, Cu, Ga, Ag, and Au, and more preferably may include Co, Ga, and Al.

According to an embodiment, the magnetic powder contains, in weight percent, 20 to 40% Nd, 0.1 to 1.0% B, 3 to 8% Co, 0.1 to 1.0% Ga, 0.1 to 1.0% Al, and the balance includes Fe and inevitable impurities. can do.

According to an embodiment, the present invention can manufacture a rare earth magnet by performing discharge plasma sintering of the above-described magnetic powder and then hot pressing it. A method for manufacturing a rare earth magnet according to an embodiment of the present invention will be described later.

According to an embodiment, the present invention can produce anisotropic rare earth magnets only by hot compression without applying an external magnetic field in the process of manufacturing the rare earth magnets. Typically, in order to improve the performance of magnets, a process of converting isotropic magnetic powder to anisotropic is required. In this process, the present invention can manufacture anisotropic rare earth magnets by sintering magnetic powder with discharge plasma and then hot compressing it to align crystal grains in one direction even without applying an external magnetic field during molding. At this time, the direction in which the crystal grains are aligned may be perpendicular to the hot compression direction.

According to an embodiment, the orientation coefficient (f) may be defined to determine the degree of anisotropy of the rare earth magnet. The orientation coefficient (f) is given in equation 1 below.

[Relationship 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.)

The orientation coefficient (f) refers to the statistical distribution of tissues arranged along the c-axis when the hot compression direction is defined as the c-axis, which is the easy magnetization axis. For example, as the orientation coefficient (f) approaches 1, it means that the tissue arranged along the c-axis increases and the degree of anisotropy increases. Conversely, the closer the orientation coefficient (f) is to 0, the less tissue is arranged along the c-axis, meaning that the degree of isotropy is high.

According to an embodiment, the rare earth magnet may have an orientation coefficient (f) defined by Equation 1 above 0.15. If the orientation coefficient is less than 0.15, the anisotropy of the rare earth magnet may be reduced, thereby reducing magnetic performance. For this reason, the orientation coefficient (f) may exceed 0.15, and more preferably 0.17 or more.

The rare earth magnet according to an embodiment of the present invention has been described above. Hereinafter, a method for manufacturing a rare earth magnet according to an embodiment of the present invention will be described with reference to FIG. 1.

1 is a flowchart illustrating a method of manufacturing a rare earth magnet according to an embodiment of the present invention.

Referring to Figure 1, the manufacturing method (S100) of a rare earth magnet according to an embodiment of the present invention is 20 to 40% by weight, Re 20 to 40%, B 0.1 to 1.0%, M 0.1 to 10%, and the balance is Fe and inevitable impurities. A step of preparing magnetic powder comprising (S110), a step of producing a rare earth sintered body by spark plasma sintering of the magnetic powder (S130), and a step of manufacturing a rare earth magnet by hot compressing the rare earth sintered body (S150). ) may include. In addition, the rare earth magnet manufactured by the above-described process may have an orientation coefficient (f) defined by the following relational equation 1 exceeding 0.15. The description of the orientation coefficient (f) has been described previously and will therefore be omitted.

[Relationship 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.)

S110

In step S110, magnetic powder containing 20 to 40% by weight, 0.1 to 1.0% of B, 0.1 to 10% of M, and the balance of Fe and inevitable impurities can be prepared. More preferably, prepare a magnetic powder containing 20 to 40% by weight of Nd, 0.1 to 1.0% of B, 3 to 8% of Co, 0.1 to 1.0% of Ga, 0.1 to 1.0% of Al, and the balance of Fe and inevitable impurities. can do.

According to an embodiment, the magnetic powder may be prepared by high-frequency melting an alloy ingot of the above-described composition, manufacturing an alloy ribbon by a melt spinning method, and coarsely crushing it, but the present disclosure is not limited thereto. It can be prepared by any method.

S130

In step S130, an isotropic rare earth sintered body can be manufactured by spark plasma sintering of the magnetic powder.

Generally, in order to sinter rare earth magnetic powder, a sintering time of 5 hours or more and a high temperature of 1,100°C or more are required. In some embodiments, a magnetic field must be applied externally to convert isotropic magnetic powder to anisotropic one. However, in the present invention, an isotropic rare earth sintered body can be manufactured by performing spark plasma sintering by applying a direct current pulse while pressurizing a sealed mold to a predetermined pressure in a predetermined vacuum atmosphere. As a result, the sintering temperature can be lowered to 800°C or lower, and the sintering time can also be reduced to less than 10 minutes. Afterwards, an anisotropic rare earth magnet can be manufactured by hot compressing the isotropic rare earth sintered body in step S150, which will be described later.

First, the magnetic powder can be charged into cylindrical graphene molds with a diameter of 10 to 20 mm and a height of 5 to 7 mm, and then the cylindrical graphene mold can be mounted in a discharge plasma sintering device.

Afterwards, a vacuum of 1x10 ^-1 to 1x10 ^-3 torr or less is created, and while the magnetic powder is pressurized at 30 to 70 MPa, a direct current pulse of 0.1 to 2000 A is applied using a pulsed DC generator. Thus, the magnetic powder can be sintered by discharge plasma.

According to an embodiment, the discharge plasma sintering may be performed by pressing the magnetic powder at 30 to 70 MPa for 3 to 7 minutes at 600 to 800°C. If the sintering temperature is less than 600°C, the magnetic powder is not sintered and the sintered body may not be formed or may not have sufficient rigidity and may be easily broken. Conversely, if the sintering temperature exceeds 800°C, the magnetic powder may recrystallize and the crystal grains of the sintered body may become coarse. As a result, the grain size may become non-uniform and the anisotropy may decrease, thereby reducing the magnetic properties of the rare earth magnet.

According to an embodiment, the compression may be performed at a pressure of 30 to 70 MPa. If the pressing pressure is less than 30 MPa, it is difficult to manufacture a high-density sintered body due to the low pressure, and if it exceeds 70 MPa, the grains of the sintered body may become coarse due to excessive pressure, which may reduce magnetic properties. For this reason, the compression can be carried out at 30 to 70 MPa, more preferably at 35 to 65 MPa, and even more preferably at 40 to 60 MPa. In addition, the sintering time may also be performed for less than 10 minutes, more preferably 3 to 7 minutes, and even more preferably 4 to 6 minutes.

S150

In step S150, a rare earth magnet can be manufactured by hot compressing the rare earth sintered body.

According to an embodiment, the hot compression is performed by charging the rare earth sintered body into cylindrical graphite molds with a diameter of 20 to 30 mm and a height of 30 mm, and then pressing at a predetermined pressure at 600 to 1,000 ° C. for 8 to 15 minutes. It can be performed by doing this. The rare earth sintered body may include isotropic first crystal grains and anisotropic second crystal grains, and the isotropic first crystal grains may be rearranged and converted into anisotropic second crystal grains through the hot compression. That is, the isotropic rare earth sintered body can be converted into an anisotropic rare earth magnet through the hot compression.

Depending on the embodiment, the hot compression may be performed by pressing the rare earth sintered body at 50 to 80 MPa for 8 to 15 minutes. If the pressing force during hot compression is less than 50 MPa or less than 8 minutes, the isotropic first crystal grains are not converted into anisotropic second crystal grains, and the first crystal grains remain in the rare earth magnet. As a result, magnetic properties may be reduced. Conversely, if the hot compression exceeds 80 MPa or exceeds 15 minutes, the crystal grains may become coarse due to excessive pressure, resulting in uneven grain size and reduced anisotropy. For this reason, the hot compression can be performed at 50 to 80 MPa, preferably at 55 to 78 MPa, and even more preferably at 60 to 75 MPa.

According to an embodiment, the hot compression may be performed at 50 to 80 MPa for 8 to 15 minutes to transform the rare earth sintered body to a reduction rate of 60 to 80%.

The method for manufacturing rare earth magnets according to an embodiment of the present invention has been described above. Below, an experimental example according to a technical embodiment of the present invention will be described. However, the technical idea of the present invention is not limited to the following experimental examples.

[Example 1]

Magnetic powder consisting of 30% by weight of Nd, 0.9% of B, 5.8% of Co, 0.6% of Ga, 0.1% of Al and the balance of Fe and inevitable impurities was charged into a graphene mold and pressured at 50 MPa at 700℃ 1x10 ^-2 torr. An Nd-Fe-B rare earth sintered body was manufactured by spark plasma sintering (SPS) for 5 minutes.

The prepared sintered body was charged into a graphene mold, and the rare earth sintered body was hot compressed at 700°C at 50 MPa for 10 minutes to produce a rare earth magnet with a reduction ratio of 60%.

[Example 2]

All processes were performed in the same manner as in Example 1 except that the rare earth sintered body was hot compressed until the reduction ratio of the rare earth magnet reached 75%.

[Comparative Example 1]

All processes except the hot compression process were performed in the same manner as in Example 1.

[Comparative Example 2]

All processes were performed in the same manner as in Example 1 except that the rare earth sintered body was hot compressed until the reduction ratio of the rare earth magnet reached 45%.

Experimental Example 1: Confirmation of crystallographic properties of rare earth magnets

Figure 2 shows the results of XRD diffraction analysis of rare earth magnets manufactured according to Examples and Comparative Examples of the present invention, and Figure 3 is a graph for comparing the crystallographic properties of rare earth magnets manufactured according to Examples and Comparative Examples of the present invention. am.

In order to confirm the crystallographic properties of the rare earth magnets manufactured according to the above examples and comparative examples, X-ray diffraction patterns were analyzed using a diffraction analyzer (iniFlex600, RIGAKU). The results are shown in Figure 2.

Referring to FIG. 2, picks of the Nd ₂ Fe ₁₄ B powder were not observed in the magnetic powder state, but the sintered body obtained by discharge plasma sintering (Comparative Example 1) and the rare earth magnet hot compressed with a reduction ratio of 45% (Comparative Example 2), With the rare earth magnets hot-compressed at a reduction ratio of 60% (Example 1) and the rare earth magnets hot-compressed at a reduction ratio of 75% (Example 2), it can be seen that the overall pick becomes clearer as the reduction ratio increases; In particular, you can see that the (006) pick is the sharpest. In other words, it can be seen that as the reduction ratio increases during hot compression, the crystal grains have anisotropy in which they are aligned in one direction.

In order to compare the crystallographic properties of specific rare earth magnets, the length/width ratio and orientation coefficient of the rare earth magnets were calculated. The orientation coefficient is a result of defining the compression direction during hot compression as c-axis, which is an easy magnetization axis, and then calculating the statistical distribution of grains aligned along the c-axis. The aspect ratio and orientation coefficient of the rare earth magnet are shown in Table 1 and Figure 3 below.

[Relational Expression 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.)

Reduction rate (%) Aspect ratio (length/width ratio) Orientation coefficient (f) Example 1
(HD-60) 60 3.2 0.19 Example 2
(HD-75) 75 6.5 0.54 Comparative Example 1
(SPS) - 1.0 0 Comparative Example 2
(HD-45) 40 2.6 0.1

Referring to Table 1 and Figure 3, it can be seen that the rare earth magnets manufactured according to Examples 1 and 2 had an aspect ratio of 3 to 8 and an orientation coefficient exceeding 0.15. This is because when the reduction ratio during hot compression is more than 50%, the isotropic first grains are rearranged and converted into anisotropic second grains.

In addition, since the orientation coefficient exceeds 0.15, it can be confirmed that the second crystal grains are aligned along the c-axis, which is the easy magnetization axis.

Conversely, if the reduction ratio is less than 50%, it can be seen that the first crystal grains remain and the crystallographic orientation is somewhat reduced. This is interpreted to be because the reduction ratio during hot compression is insufficient, so the crystal grains of the rare earth magnet are not aligned in one direction, and isotropy increases.

Experimental Example 2: Confirmation of magnetic properties of rare earth magnets according to hot compression conditions

In order to confirm the magnetic properties of rare earth magnets according to hot compression conditions, in addition to Examples 1 and 2 and Comparative Examples 1 and 2, rare earth magnets were additionally manufactured under the following conditions.

[Comparative Example 3]

All processes were performed in the same manner as in Example 1 except that the rare earth sintered body was hot compressed at 700°C and 50 MPa until the reduction ratio reached 85%.

[Comparative Example 4]

All processes were performed in the same manner as in Example 1 except that the magnetic powder was charged into the graphene mold and spark plasma sintering (SPS) was performed at 700°C and 1x10 ^-2 torr at a pressure of 80 MPa for 5 minutes.

[Comparative Example 5]

All processes were performed in the same manner as in Example 1 except that the magnetic powder was charged into the graphene mold and spark plasma sintering (SPS) was performed at 700°C and 1x10 ^-2 torr at a pressure of 100 MPa for 5 minutes.

In addition, the rare earth magnets manufactured according to the above examples and comparative examples were processed to a size of 10 mm x 10 mm x 4 mm, and then the magnetic flux density (Br), coercive force (H _ci ) and maximum magnetic energy product ((BH) _max ) were The measurements are shown in Table 2 below.

SPS pressure (MPa) Reduction rate (%) Br (kG) H _ci (kOe) (BH) _max (MGOe) Example 1 50 60 12.7 16.3 41.8 Example 2 50 75 13.6 15.8 47.2 Comparative Example 1 50 - 8.5 18.4 15.6 Comparative Example 2 50 40 11.8 14.3 37.7 Comparative Example 3 50 85 10.6 12.6 32.2 Comparative Example 4 80 60 9.4 13.5 28.3 Comparative Example 5 100 60 9.1 12.9 25.7

Referring to Table 2, in Examples 1 and 2, where the reduction ratio during hot compression was 50% or more, the magnetic flux density (Br) increased to 12.5 kG or more, the coercive force (H _ci ) increased to 15.5 kOe or more, and the maximum magnetic energy was also 40MGOe. It was confirmed that there was an abnormality.

However, in Comparative Example 3 where the reduction ratio was 85%, the magnetic flux density (Br) was 10.6kG, the coercive force (H _ci ) was 12.6kOe, and the maximum magnetic energy product was 32.2MGOe, which was reduced compared to Examples 1 and 2. This is because the crystal grains of the rare earth magnet become coarse due to excessive hot compression, resulting in uneven grain size and reduced anisotropy. For this reason, it is preferable that the reduction ratio is 60 to 75%, and more preferably 70 to 75%.

Meanwhile, referring to Comparative Examples 4 and 5, it can be seen that when the pressure exceeds 70 MPa during spark plasma sintering (SPS), the magnetic properties tend to decrease as the pressure increases. This is because the grains of the sintered body became coarse due to excessive pressure, reducing the anisotropy of the rare earth magnet. From this, it can be seen that compression during spark plasma sintering (SPS) is preferably performed at 30 to 70 MPa, more preferably 35 to 65 MPa, and even more preferably 40 to 60 MPa.

In addition, if the reduction ratio during hot compression exceeds 75% or the SPS pressure exceeds 70 MPa, it becomes prone to damage due to excessive pressure. In fact, when rare earth magnets were manufactured according to Comparative Examples 3 to 5, it was confirmed that many rare earth magnets were damaged during the manufacturing process and the defect rate increased.

The present invention described above is performed by discharge plasma sintering of magnetic powder containing 20 to 40% by weight, 0.1 to 1.0% of B, 0.1 to 10% of M, and the balance of Fe and inevitable impurities, and then hot pressing. A rare earth magnet with an orientation coefficient (f) defined by equation 1 exceeding 0.15 can be manufactured.

[Relational Expression 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.)

At this time, Re may include one or more rare earth elements selected from Nd, Ce, and Pr, and M may be provided as one or more metals selected from Co, Al, Cr, Cu, Ga, Ag, and Au.

According to an embodiment, in the method of manufacturing the rare earth magnet, the discharge plasma sintering may be performed by pressing the magnetic powder at 30 to 70 MPa for 3 to 7 minutes at 600 to 800 ° C. Hot compression can be performed by pressing the rare earth sintered body at 30 to 70 MPa for 8 to 15 minutes at 600 to 1,000°C.

As a result, the present invention can produce a rare earth magnet with a grain aspect ratio of 3 to 8, a magnetic flux density of 12.5 kG or more, and a maximum magnetic energy product of 40 MGOe or more.

The technical idea of the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible without departing from the technical idea of the present invention. It will be clear to those skilled in the art.

Claims (9)

In a rare earth magnet manufactured by discharge plasma sintering and then hot pressing magnetic powder containing 20 to 40% by weight, 0.1 to 1.0% of B, 0.1 to 10% of M, and the balance Fe and inevitable impurities,
The Re includes one or more rare earth elements selected from Nd, Ce and Pr,
The M includes one or more metals selected from Co, Al, Cr, Cu, Ga, Ag and Au,
The rare earth magnet has an orientation coefficient (f) defined by the following equation 1 exceeding 0.15,
The crystal grains of the rare earth magnet have an aspect ratio of 3 to 8.
[Relational Expression 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.) delete delete According to paragraph 1,
Rare earth magnets with a magnetic flux density (Br) of 12.5kG or more and 13.6kG or less. According to paragraph 1,
Rare earth magnets with a maximum magnetic energy product ((BH) _max ) of 40 MGOe or less than 47.2 MGOe. Preparing a magnetic powder containing, in weight percent, 20 to 40% of a rare earth metal defined as Re, 0.1 to 1.0% of B, 0.1 to 10% of a metal defined as M, and the balance containing Fe and inevitable impurities;
Pressurizing the magnetic powder at 30 to 70 MPa for 3 to 7 minutes at 600 to 800°C to produce a rare earth sintered body by spark plasma sintering; and
It includes manufacturing a rare earth magnet by hot compression by pressing the rare earth sintered body at 50 to 80 MPa for 8 to 15 minutes at 600 to 1,000°C,
The Re includes one or more rare earth elements selected from Nd, Ce and Pr,
The M includes one or more metals selected from Co, Al, Cr, Cu, Ga, Ag and Au,
A method of manufacturing a rare earth magnet, wherein the rare earth magnet has an orientation coefficient (f) defined by the following relational equation (1) exceeding 0.15.
[Relational Expression 1]

(In equation 1 above, f is the orientation coefficient of the rare earth magnet, p is the ratio of the plane diffraction intensity in the compression direction during hot compression, and p _o is the plane diffraction intensity in the same direction as p in the rare earth magnet that was not hot compressed. It is a ratio.) delete delete delete