KR102513836B1 - Method of manufacturing multiple main phase magnet and multiple main phase magnet therefrom - Google Patents

Abstract

The present invention provides a method for manufacturing a multi-phase magnet having excellent coercive force and a multi-phase magnet manufactured therefrom.

Description

Manufacturing method of multi-phase structure magnet and multi-phase structure magnet manufactured therefrom

The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2020-0104389 filed with the Korean Intellectual Property Office on August 20, 2020, all of which are included in the present invention.

The present invention relates to a method for manufacturing a multi-phase magnet. Specifically, it relates to a method for manufacturing a multi-phase magnet having high coercive force, saturation magnetic flux density, and residual magnetic flux density.

Recently, as research and development of various devices and devices become active, demand for magnets used as parts is explosively increasing. In particular, the demand for Nd-Fe-B magnets is gradually increasing due to their excellent magnetic properties.

However, in the case of Nd, as a rare earth metal, the Earth's reserves are very small, and accordingly, its price is very high, resulting in an increase in magnet prices. In addition, as the demand for Nd magnets increases, Nd supply is expected to become increasingly difficult in the future. 1 is a graph showing the production and price of rare earth elements in China. It can be seen that the price of Nd, whose production is relatively small, is on the high side.

In order to solve this problem, attempts to add other rare earth metals, such as La and Ce, which have higher production and are inexpensive, instead of Nd, are increasing. However, when other light rare earth metals other than Nd are added, the magnetic properties of the magnet are very inferior, making it difficult to replace the Nd-Fe-B magnet.

Publication No. 10-2017-0076166 (2017.07.04.)

A technical problem to be achieved by the present invention is to provide a method for manufacturing a multi-phase magnet having excellent coercive force.

However, the problem to be solved by the present invention is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to one aspect of the present invention, preparing a mixed powder by mixing a first powder having a composition of Re ¹ -Fe-B and a second powder having a composition of Re ² -Fe-B; and anisotropic bulking of the mixed powder to produce an anisotropic bulk magnet, wherein the rare earth metal included in the Re ¹ is selected from the rare earth metal and the type of the metal included in the Re ² . A method for manufacturing a multi-phase structured magnet in which at least one of the contents is different from each other is provided.

According to one aspect of the present invention, the first phase crystal grains containing Re ¹ -Fe-B; Phase 2 grains containing Re ² -Fe-B; and intergranular phase; Including, the rare earth metal included in the Re ¹ is different from each other at least one of the type and content of the rare earth metal included in the Re ² and the metal, and the maximum diameter of the first-phase crystal grain and the second-phase crystal grain is 1 μm or less, and the grain boundary phase includes a space between crystal grains of the first phase; a space between the crystal grains of the second phase; and a space between the first-phase crystal grains and the second-phase crystal grains; present at one or more positions of the first phase crystal grains, the first phase crystal grains include a first diffusion region formed by diffusion of Re ² from the outer surface of the first phase grains toward the center, and the second phase grains include the second phase grains. There is provided a multi-phase structured magnet manufactured by the method according to claim 1, including a second diffusion region formed by diffusion of Re ¹ from the outer surface of the crystal grain toward the center.

The method for manufacturing a multi-phase magnet according to an embodiment of the present invention may provide a multi-phase magnet having excellent magnetic properties due to a small crystal grain diameter.

The method for manufacturing a multi-phase magnet according to an embodiment of the present invention can provide a multi-phase magnet having excellent magnetic properties by improving coercive force and residual magnetic flux density.

The multi-phase magnet according to one embodiment of the present invention can be manufactured at a low price while having excellent magnetic properties.

A magnet with a multi-phase structure according to an embodiment of the present invention may have better magnetic properties than a magnet with a single-phase structure.

Effects of the present invention are not limited to the above-mentioned effects, and effects not mentioned will be clearly understood by those skilled in the art from the present specification.

1 is a graph showing the production and price of rare earth elements in China.
2 is a schematic cross-sectional view of a magnet with a multi-phase structure manufactured by a method according to an embodiment of the present invention.
Figure 3 is a schematic diagram showing the magnetic interaction of the multi-phase structure magnet manufactured by the method according to an embodiment of the present invention.
4 is a SEM image of a cut surface of a magnet with a multi-phase structure prepared in Example 1-1.
5 is a SEM image of a cut surface of a magnet with a multi-phase structure manufactured in Example 2-1.
6 is a graph comparing demagnetization curves of single-phase magnets prepared in Comparative Example 1 and multi-phase magnets prepared in Examples 1-4.
7 is a graph comparing demagnetization curves of single-phase magnets prepared in Comparative Example 2 and multi-phase magnets prepared in Examples 2-4.
8 is a graph of coercive force, residual magnetization, and maximum magnetic energy of the multi-phase magnets prepared in Examples 1-1 to 1-5.
9 is a graph of coercive force, residual magnetization, and maximum magnetic energy of the multi-phase magnets prepared in Examples 2-1 to 2-5.
10 is a graph of coercive force and remanent magnetization of the multi-phase structured magnets prepared in Examples 3-1 to 3-5.
11 is a graph of coercive force and residual magnetization of the multi-phase magnets prepared in Examples 4-1 to 4-5.
12 is a graph of coercive force and residual magnetization of the multi-phase magnets prepared in Examples 5-1 to 5-5.
13 shows SEM images (a), mapping images (b, c) and line scan results (d) of Ce and Nd composition distributions of the multi-phase magnets prepared in Examples 1-1 and 1-4.

In this specification, when a part is said to "include" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

Hereinafter, the present invention will be described in more detail.

According to one embodiment of the present invention, preparing a mixed powder by mixing a first powder having a composition of Re ¹ -Fe-B and a second powder having a composition of Re ² -Fe-B; and anisotropic bulking of the mixed powder to produce an anisotropic bulk magnet, wherein the rare earth metal included in the Re ¹ is selected from the rare earth metal and the type of the metal included in the Re ² . A method for manufacturing a multi-phase structured magnet in which at least one of the contents is different from each other is provided.

According to one embodiment of the present invention, the multi-phase structure magnet manufactured by the manufacturing method of the multi-phase structure magnet is prepared from the first powder and the second powder including crystal grains of different compositions, and the first crystal grains and the second powder of different composition Since it includes two crystal grains, and the first crystal grain and the second crystal grain include diffusion regions formed by diffusion of other elements from the outer surface, magnetic properties such as coercive force and saturation magnetization may be excellent.

Hereinafter, each step will be described in detail.

According to one embodiment of the present invention, a step of preparing a first powder having a composition of Re ¹ -Fe-B and a second powder having a composition of Re ² -Fe-B may be performed first.

According to one embodiment of the present invention, the first powder and the second powder may be prepared by independently grinding an alloy ribbon or by performing a HDDR process on an alloy powder.

Specifically, the first powder and the second powder each independently preparing an alloy having a composition of Re ¹ -Fe-B or Re ² -Fe-B; Manufacturing a ribbon by melting the alloy and then rapidly cooling it; and pulverizing the ribbon into powder. It can be manufactured using, and the manufacturing method is not limited to the above-listed methods.

According to one embodiment of the present invention, in the step of preparing the alloy, the alloy may be prepared by adding a non-rare earth metal to improve properties in addition to the rare earth metal, iron, and boron. For example, Ga, Co, Al, Cu, Nb, Ti, Si, Zr, Ta, V, Mo, Mn, Zn, Ni, Cr, Pb, Sn, In, Mg, Ag, Ge, etc. may be added, , The non-rare earth metal may be included in an amount of about 10 mol% or less.

Alternatively, an alloy powder having a composition of Re ¹ -Fe-B or Re ² -Fe-B is obtained and hydrogenation, disproportionation, desorption, and recombination are performed according to the HDDR process. The first powder and the second powder may be manufactured through a process. Through the HDDR process, crystal grains of powder having large crystal grains can be refined and used as a raw material for multi-phase magnetic powder.

According to one embodiment of the present invention, the first powder and the second powder may be crystalline or amorphous, preferably amorphous. Each powder can be made crystalline or amorphous by controlling the manufacturing process, and for example, crystalline or amorphous powder can be produced by controlling the cooling rate.

According to one embodiment of the present invention, the first powder and the second powder may be amorphous. When the first powder and the second powder are amorphous powders, fewer ReFe ₂ phases, an impurity phase included in the manufactured multi-phase magnet, may be formed, resulting in excellent magnetic properties.

According to one embodiment of the present invention, when the first powder and the second powder are crystalline powders, they may be formed of crystal grains having a maximum diameter of 1 μm or less. By being made of small crystal grains having a maximum diameter of 1 μm or less, the magnetic properties of the multi-phase structured magnet may be excellent.

According to one embodiment of the present invention, the first powder and the second powder may be isotropic powder or anisotropic powder. Specifically, in the anisotropic bulking process performed after mixing the powders later, isotropic or anisotropic powders may be selected and used according to the anisotropic bulking method.

For example, an anisotropic bulking step of aligning the mixed powder in a magnetic field; And pressure sintering; In the case of including, the first powder and the second powder included in the mixed powder may be an anisotropic powder.

According to one embodiment of the present invention, the rare earth metal included in the Re ¹ is different from the rare earth metal included in the Re ² and at least one of the type and content of the metal.

Specifically, Re ¹ and Re ² are each independently 1 selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu It may include more than one kind of rare earth metal, and Re ¹ and Re ² may include different types of rare earth metals, include the same type of rare earth metal in different amounts, or include different types of rare earth metals and their respective amounts. can be different Preferably, Re ¹ includes Nd and Pr, and Re ² may include Nd, Ce, and La. Alternatively, both Re ¹ and Re ² may include Nd and Ce, but may have different contents. The rare earth metal element is not limited to the chemical species listed above, and other rare earth metal elements other than the chemical species listed above may be used if necessary.

According to one embodiment of the present invention, Re ² has a composition of Nd _1-x Ce _x , wherein x is 0.2 to 1, 0.3 to 1, 0.2 to 0.8, 0.3 to 0.8, 0.2 to 0.6, 0.3 to 0.6 or It may be from 0.4 to 0.6. In the case of having a composition within the above range, the magnetic properties of the manufactured magnet may be excellent.

According to one embodiment of the present invention, the particle diameters of the first powder and the second powder may be 3 to 500 μm, specifically, the particle diameters of the first powder and the second powder are 3 μm or more and 10 μm It may be 50 μm or more, 125 μm or more, 500 μm or less, 300 μm or less, or 200 μm or less.

According to one embodiment of the present invention, a mixed powder is prepared by mixing a first powder having a composition of Re ¹ -Fe-B and a second powder having a composition of Re ² -Fe-B.

The mixing may be performed through a method commonly used in the art, and may be performed, for example, using a device such as a 3D mixer, a magnetic stirrer, or an acoustic resonance mixer. In addition, the mixing may be performed until the first powder and the second powder are uniformly mixed, and the mixing time may vary depending on the mixing method and the device used.

According to one embodiment of the present invention, the first powder and the second powder are 1:9 to 9:1, 1:9 to 7:3, 2.5:7.5 to 9:1, 2.5:7.5 to 7:3 , 5:5 to 9:1, 5:5 to 7:3 or 5:5 to 6.25: may be mixed in a weight ratio of 3.75. The multi-phase magnet of the present invention includes crystal grains having different compositions, and has a multi-phase structure due to a diffusion region formed thereby, and thus can have excellent magnetic properties. First powder and second powder are mixed at a weight ratio within the above range. In the case of mixing, there may be an effect of improving magnetic properties due to the magnetic exchange interaction between crystal grains or crystal grains having different compositions and the diffusion region.

According to one embodiment of the present invention, the first powder and the second powder may be mixed so that the atomic ratio of Nd: Ce is 7:3 to 3:7 in the total composition of the multi-phase structured magnet to be manufactured. . That is, the weight ratio of the first powder and the second powder may be adjusted in consideration of the composition of each powder and the composition of the magnet to be manufactured. For example, when Re ¹ of the first powder is composed of Nd and Re ² of the second powder is composed of Nd _0.5 Ce _0.5 , the weight ratio of the first powder to the second powder may be 4:6 or more. .

Next, the mixed powder is anisotropically bulked to produce an anisotropic bulk magnet.

According to one embodiment of the present invention, the anisotropic bulking means a process in which the raw material powder is processed into an anisotropic bulk magnet by sintering in a state in which the crystallographic easy direction of magnetization of crystal grains is aligned in one direction.

According to one embodiment of the present invention, the anisotropic bulking comprises aligning the mixed powder in a magnetic field; And pressure sintering; may include, or the step of pressure sintering the mixed powder first; and hot-deforming.

The step of aligning the magnetic field is a process of aligning the easily magnetized direction of the mixed powder in one direction. Specifically, it may be to fill a molding mold with mixed powder and apply a magnetic field of 100 G to 70,000 G to align a direction in which magnetization of the mixed powder is easy in the direction of the applied magnetic field. In addition, the powder may be molded by applying a pressure of 1 GPa or less when the magnetic field is applied, but the pressure is not necessarily applied.

According to one embodiment of the present invention, the mixed powder may be first pressure-sintered. The pressurized sintering is not particularly limited in the method as long as sintering can be performed, but is performed by any one method selected from the group consisting of, for example, hot press sintering, hot isostatic pressure sintering, discharge plasma sintering, and microwave sintering it could be The pressure sintering process is a step of densely binding the magnetic powder, which can be referred to as a step of bulking the magnet.

The pressurized sintering may be performed, for example, using hot press equipment, and specifically, after inserting the powder into a mold in the chamber, raising the temperature to a specific temperature in a vacuum or inert gas atmosphere, applying pressure to the powder to sinter the device may be using

The pressure sintering may be performed by pressing at 50 to 1000 MPa at a temperature of 500 to 900 °C. In the pressure sintering step, the mixed powder may be processed into a bulk form.

According to one embodiment of the present invention, the hot deformation process is not limited to a specific method, and may be performed by a method selected from hot extrusion, hot rolling, and hot forging, preferably by hot forging. . Crystal grains may be aligned and anisotropic in the hot deformation process.

According to one embodiment of the present invention, the hot deformation process is performed at a temperature of 500 to 900 ° C, 500 to 800 ° C, or 500 to 650 ° C, under a pressure of 20 to 500 MPa, 50 to 300 MPa, or 50 to 150 MPa. it may be When the hot deformation process is performed within the temperature and pressure ranges within the above ranges, bulking of the powder and crystallographic anisotropy of crystal grains may be possible, and there may be an effect of improving magnetic properties.

According to one embodiment of the present invention, the hot deformation may be a process of deforming the bulk magnet, and the bulk magnet may be deformed by hot deformation such that the strain rate is 1 to 2. The strain can be expressed by Equation 1 below.

[Equation 1]

ε = ln(h ₀ /h)

In Equation 1, ε means strain, h ₀ is the height of the initial sample, and h is the height of the sample after deformation.

When the strain satisfies a value within the above range, the residual magnetic flux density may be increased by grain anisotropy. Specifically, during the hot deformation process, the shape of the spherical crystal grains may be changed into a plate shape along with the crystal grain growth. The plate-shaped shape may correspond to a shape elongated in a direction perpendicular to a direction in which magnetization is easy. The melting point of the grain boundary phase is lower than the process temperature, so the grain boundary phase exists in a liquid phase during the process. At this time, when the sample is pressed, the internal crystal grains rotate, and the direction of easy magnetization of each crystal grain is horizontally aligned with the pressing direction, resulting in crystallographic may be anisotropic.

In addition, the hot deformation may transform the bulk magnet at a strain rate of 0.001/s to 1.0/s, and the strain rate may be expressed by Equation 2 below.

[Equation 2]

는 변형 속도이고, 상기 ε는 변형률이고, 상기 t는 시간이다. remind

is the strain rate, ε is the strain rate, and t is the time.

The strain rate may vary depending on conditions such as powder composition, crystal grain diameter, and process temperature.

According to one embodiment of the present invention, after manufacturing the anisotropic bulk magnet as described above, post-heat treatment may be performed to manufacture a multi-phase magnet.

Through the post-heat treatment process, Re ¹ or Re ² is diffused to increase the diffusion area, and to increase the magnetic interaction between the first-phase crystal grains and the second-phase crystal grains included in the multi-phase magnet, so that the coercive force, residual magnetic flux density, etc. characteristics can be improved.

According to one embodiment of the present invention, the post-heat treatment may be performed at a temperature of 400 to 800 °C, 500 to 800 °C, or 700 to 800 °C for 10 to 600 minutes, 30 to 500 minutes, or 50 to 200 minutes. . When the post-heat treatment is performed under conditions within the above temperature and time ranges, the magnetic interaction of the multi-phase structured magnet may be increased more efficiently.

A multi-phase magnet manufactured by the manufacturing method according to an embodiment of the present invention includes a first phase crystal grain including Re ¹ -Fe-B; Phase 2 grains containing Re ² -Fe-B; and intergranular phase; Including, the rare earth metal included in the Re ¹ is different from each other at least one of the type and content of the rare earth metal included in the Re ² , and the maximum diameter of the first-phase crystal grains and the second-phase crystal grains is 1 μm Hereinafter, the grain boundary phase includes a space between crystal grains of the first phase; a space between the crystal grains of the second phase; and a space between the first-phase crystal grains and the second-phase crystal grains; present at one or more positions of the first phase crystal grains, the first phase crystal grains include a first diffusion region formed by diffusion of Re ² from the outer surface of the first phase grains toward the center, and the second phase grains include the second phase grains. A second diffusion region formed by diffusion of Re ¹ from the outer surface of the crystal grain toward the center thereof is included.

The multi-phase structure (Multi Main Phase; MMP) includes various phases including a first diffusion region including Re ² and a second diffusion region including Re ¹ in each of the first phase crystal grains and the second phase crystal grains. can mean structure. Due to this multi-phase structure, the multi-phase structure magnet manufactured by the method according to one embodiment of the present invention may have excellent magnetic properties.

2 is a schematic cross-sectional view of a magnet having a multi-phase structure according to an embodiment of the present invention. Hereinafter, a multi-phase structure magnet according to an embodiment of the present invention will be described in detail with reference to FIG. 2 .

A multi-phase structure magnet 1 according to an embodiment of the present invention includes a first phase crystal grain 10; Phase 2 crystal grains 20; and a grain boundary phase 30, wherein the first phase grains 10 may include a first diffusion region 110, and the second phase grains 20 may include a second diffusion region 210. there is.

The first phase grains 10 include Re ¹ -Fe-B, and the second phase grains 20 include Re ² -Fe-B. Re ¹ and Re ² include rare earth metals, and the type of rare earth metal included in Re ¹ is different from the type of rare earth metal included in Re ² by at least one type. That is, the Re ¹ and the Re ² may each include a single type of rare earth metal different from each other, or may include one or more types of different rare earth metals in different compositions, and may include the first phase crystal grains and the second type of rare earth metal. The composition of the phase grains can be different for rare earth metals.

According to one embodiment of the present invention, the Re ¹ and the Re ² may each independently include one or more rare earth metals. Specifically, Re ¹ and Re ² include one or more of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu For example, Re ¹ may include Nd, and Re ² may include Nd and Ce. Preferably, Re ¹ may include Nd and Pr, and Re ² may include Nd, Ce, and La. The rare earth metal element is not limited to the chemical species listed above, and other rare earth metal elements may be used as needed.

According to one embodiment of the present invention, the multi-phase magnet has a composition of Nd _a R _b Fe _100-abcd M _c B _d , wherein R is Sc, Y, La, Ce, Pr, Pm, Sm, Eu, Gd , Tb, Dy, Ho, Er, Tm, Yb, and Lu, wherein M is Ga, Co, Al, Cu, Nb, Ti, Si, Zr, Ta, V, Mo, Mn, Zn , includes at least one of Ni, Cr, Pb, Sn, In, Mg, Ag, and Ge, wherein a is 0 or more and 20 or less, b is 0 or more and 20 or less, c is 0 or more and 15 or less, and d may be greater than or equal to 0 and less than or equal to 15. The composition may be a total composition including all of the first-phase crystal grains, the second-phase crystal grains, and the composition of the grain boundary phase, and may satisfy the above composition formula.

According to one embodiment of the present invention, the first-phase crystal grains 10 may include a first diffusion region 110, and the second-phase crystal grains 20 may include a second diffusion region 210. . The first diffusion region 110 and the second diffusion region 210 may be formed as Re ² and Re ¹ diffuse from outer surfaces of the first-phase grains and the second-phase grains toward the center, respectively. . That is, the first diffusion region 110 and the second diffusion region 210 may have structures formed by penetration and diffusion of rare earth metals of different phases during the manufacturing process of a multi-phase magnet.

The first-phase crystal grains 10 and the second-phase crystal grains 20 included in the multi-phase structure magnet manufactured by the manufacturing method according to the embodiment of the present invention have an aspect ratio of greater than 1 and less than or equal to 10, 2 to 5, or 3 to 4 may be in the form of That is, the first-phase crystal grains 10 and the second-phase crystal grains 20 are pressurized while being manufactured according to the manufacturing method according to one embodiment of the present invention, and can be molded into a flat shape while pressure is applied to the crystal grains, and the aspect ratio is A multi-phase structured magnet having a form within the above range can be manufactured.

The multi-phase structure magnet 1 according to one embodiment of the present invention may include a grain boundary phase 30, wherein the grain boundary phase 30 includes a space between the first phase crystal grains, a space between the second phase grains, and/or Alternatively, it may be located in a space between the first-phase crystal grains and the second-phase crystal grains. That is, the grain boundary phase 30 may be located in a space between distinct and independent crystal grains.

The grain boundary phase 30 may be a region melted by high temperature or high pressure during the manufacturing process of the multi-phase structured magnet 1, and accordingly, Re ¹ and the second phase included in the first phase crystal grain 10 It may serve as a passage through which Re ² included in the crystal grains 20 diffuses.

3 shows a schematic diagram of a magnetic interaction of a multi-phase structure according to an embodiment of the present invention.

Referring to FIGS. 2 and 3 , in the multi-phase structure magnet manufactured by the method according to an embodiment of the present invention, the first diffusion region 110, the second diffusion region 210, and the grain boundary phase 30 are It can affect the magnetic interaction, and thus the magnetic properties of the multi-phase magnet can be excellent. Specifically, in the case of a multi-phase structure magnet including the first diffusion region 110 and the second diffusion region 210, the center of the first phase crystal grain (not shown) and the first diffusion region 110 are located at a short distance. The magnetic exchange interaction can be excellent, and the magnetic exchange interaction according to the short distance between the center of the second phase crystal grain (not shown) and the second diffusion region 110 is excellent, so that the magnetic properties of the multi-phase structure magnet can be improved. It can be excellent (Fig. 3 (a)), and at the same time, the magnetic exchange interaction is excellent even between the first phase grains 10 and the second phase grains 20 of different compositions (Fig. 3 (b)) The magnetic properties of the structured magnet may be better. The magnetic exchange interaction may mean that a relatively strong magnetic material interacts with a magnetic material having a lower magnetic property in a form of preventing magnetization reversal among magnetic materials having different compositions.

The multi-phase magnet manufactured by the method according to an embodiment of the present invention may have a coercive force of 5 to 50 kOe or more. Specifically, the multi-phase magnet may have a coercive force of 5 kOe or more, 10 kOe or more, or 15 kOe or more, and 50 kOe or less, 40 kOe or less, or 35 kOe or less.

Hereinafter, examples will be described in detail to explain the present invention in detail. However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention is not construed as being limited to the embodiments described below. The embodiments herein are provided to more completely explain the present invention to those skilled in the art.

Preparation Example 1

After manufacturing Fe, Nd, FeB, Ga, and Co metal into an ingot with a composition of Nd _13.6 Fe _73.6 B _5.6 Ga _0.6 Co _6.6 by arc-melting, the ingot is melt-spun at a speed of 28 m/s made of ribbon. The prepared ribbon was pulverized into particles having a maximum diameter of 100 μm to prepare a first crystalline powder.

Preparation Example 2

In Preparation Example 1, a second crystalline powder was prepared in the same manner as in Preparation Example 1, except that an ingot having a composition of (Nd _0.6 Ce _0.4 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

Preparation Example 3

In Preparation Example 1, a third crystalline powder was prepared in the same manner as in Preparation Example 1, except that an ingot having a composition of (Nd _0.8 Ce _0.2 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

Production Example 4

In Preparation Example 1, a fourth crystalline powder was prepared in the same manner as in Preparation Example 1, except that an ingot having a composition of (Nd _0.7 Ce _0.3 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

Preparation Example 5

In Preparation Example 1, a fifth amorphous powder was manufactured in the same manner as in Preparation Example 1, except that the ingot was melt-spun at a speed of 35 m/s to produce a ribbon.

Preparation Example 6

In Preparation Example 5, a sixth amorphous powder was prepared in the same manner as in Preparation Example 5, except that an ingot having a composition of (Nd _0.6 Ce _0.4 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

Preparation Example 7

In Preparation Example 5, a seventh amorphous powder was prepared in the same manner as in Preparation Example 5, except that an ingot having a composition of (Nd _0.7 Ce _0.3 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

Preparation Example 8

In Preparation Example 5, an amorphous eighth powder was prepared in the same manner as in Preparation Example 5, except that an ingot having a composition of (Nd _0.4 Ce _0.6 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

Preparation Example 9

In Preparation Example 5, a ninth amorphous powder was prepared in the same manner as in Preparation Example 5, except that an ingot having a composition of (Nd _0.2 Ce _0.8 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

Preparation Example 10

In Preparation Example 5, a tenth amorphous powder was prepared in the same manner as in Preparation Example 5, except that an ingot having a composition of Ce _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 was used.

The manufacturing conditions of Preparation Examples 1 to 10 are summarized in the table below.

Furtherance crystalline Preparation Example 1 Nd _13.6 Fe _73.6 B _5.6 Ga _0.6 Co _6.6 crystalline Preparation Example 2 (Nd _0.6 Ce _0.4 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 crystalline Preparation Example 3 (Nd _0.8 Ce _0.2 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 crystalline Production Example 4 (Nd _0.7 Ce _0.3 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 crystalline Preparation Example 5 Nd _13.6 Fe _73.6 B _5.6 Ga _0.6 Co _6.6 amorphous Preparation Example 6 (Nd _0.6 Ce _0.4 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 amorphous Preparation Example 7 (Nd _0.7 Ce _0.3 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 amorphous Preparation Example 8 (Nd _0.4 Ce _0.6 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 amorphous Preparation Example 9 (Nd _0.2 Ce _0.8 ) _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 amorphous Preparation Example 10 Ce _13.6 Fe _bal B _5.6 Ga _0.6 Co _6.6 amorphous

Example 1-1

A mixed powder was prepared by mixing the first powder prepared in Preparation Example 1 and the second powder prepared in Preparation Example 2 at a weight ratio of 1:3. The mixed powder was put into a mold of a pressure sintering equipment, mounted, and pressed and sintered at 700 ° C. at 100 MPa for 3 minutes to manufacture a bulk magnet. The prepared bulk magnet was hot deformed at a strain rate of 0.1 s ⁻¹ at 700° C. so that the strain was 1.5 to prepare an anisotropic bulk magnet.

Example 2-1

In Example 1-1, an anisotropic bulk magnet was manufactured in the same manner as in Example 1-1, except that the fifth powder was used instead of the first powder and the sixth powder was used instead of the second powder.

Example 3-1

In Example 2-1, in the same manner as in Example 2-1, except that the eighth powder was used instead of the sixth powder and mixed so that the weight ratio of the fifth powder to the eighth powder was 1:1. An anisotropic bulk magnet was prepared.

Example 4-1

In Example 2-1, the same method as in Example 2-1 except that the ninth powder was used instead of the sixth powder and mixed so that the weight ratio of the fifth powder to the ninth powder was 5:3. An anisotropic bulk magnet was prepared.

Example 5-1

In Example 2-1, the same method as in Example 2-1 was used except that the 10th powder was used instead of the 6th powder and the mixture was mixed so that the weight ratio of the 5th powder to the 10th powder was 7:3. An anisotropic bulk magnet was prepared.

Example 1-2, 2-2, 3-2, 4-2, 5-2

The multi-phase magnets prepared in Examples 1-1, 2-1, 3-1, 4-1 or 5-1 were post-heat treated at 600° C. for 1 hour to prepare multi-phase magnets.

Example 1-3, 2-3, 3-3, 4-3, 5-3

The multi-phase magnets prepared in Examples 1-1, 2-1, 3-1, 4-1 or 5-1 were post-heat treated at 600° C. for 3 hours to prepare multi-phase magnets.

Example 1-4, 2-4, 3-4, 4-4, 5-4

The multi-phase structure magnets prepared in Examples 1-1, 2-1, 3-1, 4-1 or 5-1 were post-heat treated at 700° C. for 1 hour to prepare multi-phase structure magnets.

Example 1-5, 2-5, 3-5, 4-5, 5-5

The multi-phase magnets prepared in Examples 1-1, 2-1, 3-1, 4-1 or 5-1 were post-heat treated at 700° C. for 3 hours to prepare multi-phase magnets.

Comparative Example 1

After preparing the fourth powder prepared in Preparation Example 4, it was put into a pressure sintering equipment and mounted, and pressure sintered at 700 ° C. at 100 MPa for 3 minutes to manufacture a bulk magnet. The prepared bulk magnet was hot deformed at a strain rate of 0.1 s ⁻¹ at 700° C. so that the strain was 1.5 to prepare an anisotropic bulk magnet. The prepared magnet was post-heat treated at 700° C. for 1 hour to prepare a single-phase structured magnet.

Comparative Example 2

In Comparative Example 1, a single-phase structured magnet was manufactured in the same manner as in Comparative Example 1, except that the seventh powder was used instead of the fourth powder.

Confirmation of SEM images

The multi-phase structured magnets prepared in Examples 1-1 and 2-1 were cut, and the cut surfaces were photographed at x5000 to x50000 magnification using a scanning electron microscope (SEM, JEOL Ltd., 7001F).

4 and 5 show SEM images of cut surfaces of the multi-phase magnets prepared in Examples 1-1 and 2-1, respectively.

Referring to FIG. 4 , it can be observed that the multi-phase magnet manufactured in Example 1-1 includes crystal grains having a diameter of about 200 nm. In addition, referring to FIG. 5 , it can be confirmed that the multi-phase structure magnet manufactured in Example 2-1 also includes crystal grains of a similar shape, and the internal crystal grains are better aligned in a single direction. As will be described later, depending on the crystal grain shape, the magnetic properties of the magnet, such as the residual magnetization value, may be comparatively better, and the magnetic exchange interaction may be more effective.

Measurement and evaluation of coercivity and remanent magnetization

The multi-phase magnets prepared in Examples 1-1 to 5-5 and the single-phase magnets prepared in Comparative Example 1 were processed to a size of 3 cm x 3 cm x 1 cm, and then magnetized using a pulse magnetic field of 7T. The magnetized sample was swept by applying a magnetic field ranging from -1.8 T to 1.8 T using a vibration sample analyzer (VSM, LakeShore), and magnetic properties of coercive force and remanent magnetization were measured.

6 shows the demagnetization curves of the magnets prepared in Examples 1-4 (red) and Comparative Example 1 (black), and FIG. 7 shows magnets manufactured in Examples 2-4 (red) and Comparative Example 2 (black). The demagnetization curve of a magnet is shown.

Referring to FIGS. 6 and 7 , it can be seen that the magnetic properties of the multi-phase magnet are superior to those of the single-phase magnet. In addition, in the case of multi-phase structured magnets, it can be confirmed that the magnetic properties (residual magnetization) of the magnets when amorphous powder is used are superior to those when crystalline powder is used.

8 to 12, Examples 1-1 to 1-5, Examples 2-1 to 2-5, Examples 3-1 to 3-5, Examples 4-1 to 4-5, and Example 5- Graphs of coercive force, residual magnetization, and maximum magnetic energy of the multi-phase structured magnets prepared in 1 to 5-5 are shown.

Referring to FIGS. 8 to 12 , it can be seen that the coercive force, residual magnetization, and maximum magnetic energy product of the multi-phase magnet are improved by post-heat treatment. Specifically, in most of the examples, it can be confirmed that the magnetic properties are improved most excellently when post-heat treatment is performed at 600° C. for 3 hours or 700° C. for 1 hour. In particular, it can be confirmed that the magnetic properties of Examples 3-4 are the best.

Confirmation of expansion of diffusion area by post-heat treatment

Scanning electron microscope (SEM) images of the multi-phase magnets prepared in Examples 1-1 and 1-4 were taken. Specifically, SEM images of the multi-phase magnets prepared in Examples 1-1 and 1-4 were taken using a scanning electron microscope (SEM, JEOL Ltd., 7001F) at x5000 magnification, and powder on the SEM images The boundary curve of the liver is shown. In addition, mapping images of Ce and Nd elements were taken with an energy dispersive spectrometer (EDS), and contents of Ce and Nd elements were measured by line scan on a straight line between crystal grains (a straight line on the SEM image).

13 shows SEM images (a), mapping images (b, c) of the Ce and Nd composition distributions, and line scan results (d) of the multi-phase magnets prepared in Examples 1-1 and 1-4. was In Examples 1-4, it can be seen that the diffusion area of Ce and Nd is wider at the interface between the first powder and the second powder. That is, it can be seen that the rare earth metals having different compositions can be diffused to a deeper region through the post-heat treatment, and thus the manufactured multi-phase structured magnet has excellent magnetic properties.

8 to 13, the area in which the Re ¹ component of the first powder and the Re ² component of the second powder diffuse each other increases through post-heat treatment at an appropriate temperature and time, thereby forming a multi-phase structure having better magnetic properties. It can be confirmed that the post-heat treatment temperature and time have a great influence on the magnetic properties of the multi-phase structured magnet.

Summarizing the above, it can be confirmed that the multi-phase structured magnet manufactured by the manufacturing method according to an embodiment of the present invention has excellent coercive force and residual magnetization including first-phase crystal grains, second-phase crystal grains, and diffusion regions.

1: multi-phase structure magnet
10: phase 1 crystal grains
20: phase 2 crystal grains
30: granular phase
110: first diffusion region
210: second diffusion region

Claims (18)

preparing a mixed powder by mixing a first powder having a composition of Re ¹ -Fe-B and a second powder having a composition of Re ² -Fe-B;
Anisotropic bulking of the mixed powder to produce an anisotropic bulk magnet; and
post-heating the prepared anisotropic bulk magnet;
As a method of manufacturing a multi-phase structure magnet comprising a,
Re ¹ and Re ² are each independently one or more rare earths selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu contains metal;
Re ² includes at least Ce,
The rare earth metal included in Re ¹ is different from the rare earth metal included in Re ² and at least one of the metal type and metal content.
Manufacturing method of multi-phase structured magnet.
According to claim 1,
The method of manufacturing a multi-phase structured magnet, wherein the first powder and the second powder are crystalline.
According to claim 1,
The method of manufacturing a multi-phase structured magnet in which the first powder and the second powder are amorphous.
According to claim 2,
The method of manufacturing a multi-phase structure magnet, wherein the first powder and the second powder are made of crystal grains having a diameter of 1 μm or less.
According to claim 1,
Wherein the first powder and the second powder are mixed in a weight ratio of 1:9 to 9:1.
According to claim 1,
The first powder and the second powder are each independently preparing an alloy having a composition of Re ¹ -Fe-B or Re ² -Fe-B; Manufacturing a ribbon by melting the alloy and then rapidly cooling it; and crushing and pulverizing the ribbon.
delete According to claim 1,
Wherein Re ² has a composition of Nd _1-x Ce _x , where x is 0.2 to 1.
According to claim 1,
The first powder and the second powder are mixed so that the atomic ratio of Nd: Ce is 7: 3 to 3: 7 in the total composition of the multi-phase structure magnet to be manufactured.
According to claim 1,
The anisotropic bulking step of pressure sintering; And hot-deforming; method of manufacturing a multi-phase structured magnet comprising a.
According to claim 10,
The pressure sintering is a method for producing a multi-phase structured magnet that is performed by pressing at a temperature of 500 to 900 ° C. at 50 to 1000 MPa.
According to claim 10,
The hot deformation process is a method of manufacturing a multi-phase structured magnet that is performed at a temperature of 500 to 900 ° C. and under a pressure of 20 to 500 MPa.
According to claim 10,
The hot deformation is a method for producing a multi-phase structured magnet selected from hot rolling, hot forging and hot extrusion.
According to claim 10,
The hot deformation is a method for manufacturing a multi-phase structured magnet that is performed so that the strain expressed by Equation 1 below is 1 to 2.
[Equation 1]
ε = ln(h ₀ /h)
In Equation 1, ε means strain, h ₀ is the height of the initial sample, and h is the height of the sample after deformation.
delete According to claim 1,
The post-heat treatment is performed at a temperature of 400 to 800 ° C. for 10 to 600 minutes.
Phase 1 grains containing Re ¹ -Fe-B; Phase 2 grains containing Re ² -Fe-B; and intergranular phase; including,
Re ¹ and Re ² are each independently one or more rare earths selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu contains metal;
Re ² includes at least Ce,
The rare earth metal included in Re ¹ is different from the rare earth metal included in Re ² and at least one of the metal type and metal content,
The maximum diameter of the first-phase crystal grains and the second-phase crystal grains is 1 μm or less,
The grain boundary phase may include a space between crystal grains of the first phase; a space between the crystal grains of the second phase; and a space between the first-phase crystal grains and the second-phase crystal grains; present in one or more positions of
The first-phase crystal grains include a first diffusion region formed by diffusion of Re ² from an outer surface of the first-phase crystal grain in a central direction;
The multi-phase structure magnet manufactured by the method according to claim 1, wherein the second-phase crystal grains include a second diffusion region formed by diffusion of Re ¹ from the outer surface of the second-phase crystal grain toward the center.
According to claim 17,
The multi-phase magnet has a composition of Nd _a R _b Fe _100-abcd M _c B _d , where R is Sc, Y, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, It includes at least one of Tm, Yb, and Lu, wherein M is Ga, Co, Al, Cu, Nb, Ti, Si, Zr, Ta, V, Mo, Mn, Zn, Ni, Cr, Pb, Sn, A multi-phase structure comprising at least one of In, Mg, Ag, and Ge, wherein a is greater than 0 and less than 20, b is greater than 0 and less than 20, c is greater than 0 and less than 15, and d is greater than 0 and less than 15 magnet.

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