JP7167665B2 - Rare earth magnet and manufacturing method thereof - Google Patents

Description

The present disclosure relates to an R—Fe—B system rare earth magnet (R is a rare earth element) and a method for producing the same. In particular, the present disclosure relates to an R—Fe—B rare earth magnet whose coercive force is suppressed from decreasing at high temperatures, and a method for producing the same.

An R--Fe--B rare earth magnet comprises a main phase and grain boundary phases around the main phase. The main phase has a composition represented by R ₂ Fe ₁₄ B and is a magnetic phase. This main phase exhibits strong magnetism. On the other hand, the grain boundary phase exists around the main phase and separates the main phases magnetically. This magnetic division enhances the coercive force of the R—Fe—B system rare earth magnet.

Various attempts have been made to enhance this magnetic separation effect. For example, Patent Document 1 discloses a rare earth magnet obtained by using a rare earth magnet having a main phase and a grain boundary phase as a precursor and infiltrating a modifier into the interior of the precursor.

In the rare earth magnet disclosed in Patent Document 1, the coercive force of the entire rare earth magnet is enhanced by having an intermediate phase between the main phase and the grain boundary phase.

International Publication No. 2014/196605A1

Due to their high performance, R--Fe--B rare earth magnets are being used in a wide variety of fields. Therefore, the use of R--Fe--B rare earth magnets in high-temperature environments is also increasing. Also, when an R--Fe--B rare earth magnet is used in a high-output motor and the high output is maintained for a long period of time, the temperature of the R--Fe--B rare earth magnet may rise due to self-heating of the motor. be.

It is known that the coercive force of an R--Fe--B rare earth magnet may decrease when the temperature is high.

Accordingly, the present inventors have found that there is a demand for an R--Fe--B rare earth magnet which is capable of suppressing a decrease in coercive force even at high temperatures. In this specification, high temperature means a temperature range of 100 to 170°C, particularly 140 to 160°C. Further, room temperature means a range of 20 to 25°C. An R--Fe-- _B rare earth magnet comprises a main phase and a grain boundary phase existing around the main phase, and the main phase contains a phase having a composition represented by _{R.sub.2Fe.sub.14B} . It refers to a magnet that has

The present disclosure has been made to solve the above problems. An object of the present disclosure is to provide an R--Fe--B rare earth magnet in which a decrease in coercive force is suppressed even at high temperatures, and a method for producing the same.

In order to achieve the above object, the present inventors have made intensive studies and completed the rare earth magnet of the present disclosure and the method for producing the same. The rare earth magnet of the present disclosure and its manufacturing method include the following embodiments.
<1> The overall composition is (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _(100-pqrstu) Co _q B _r Ga _{s Cut} M ¹ _u ·(R ² _a R ³ _b M ² _(1-a-b) ) _v (R ¹ is one or more rare earth elements other than Nd, Pr, Ce, and La, and M ¹ is one or more elements selected from the group consisting of Al, Au, Ag, Zn, In, and Mn, and an unavoidable impurity element, and R ² is Nd, Pr, Pm, Sm, Eu, and from the group consisting of Gd R ³ is one or more selected elements, R ³ is one or more rare earth elements other than R ² , and M ² is R ² _a R ³ _b M ^{2 (} _1- one or more alloying elements and unavoidable impurity elements that lower the melting point of _ab) below the melting point of ^R2 ,
p, q, r, s, t, u, and v in atomic %,
5.0≦p≦20.0,
0≤q≤8.0,
4.0≦r≦6.5,
0≤s≤0.5,
0≤t≤0.5,
0≤u≤2.0, and 0≤v≤10.0
and
x, y, z, w, a, and b, in molar ratios,
0.200≦x≦0.400,
0≤y≤0.100,
0.100≦z≦0.200,
0≤w≤0.100
0.50≦a≦0.80 and 0≦b≦0.10
is ), and
It has a main phase and a grain boundary phase existing around the main phase,
The main phase contains rare earth elements in a molar ratio of Nd:Pr:Ce:La:R ¹ =(1- _xm - _ym - _zm - _wm ): _xm : _ym : _zm : _wm and having a phase with a (Nd, Pr, Ce, La, R ¹ ) ₂ (Fe, Co) ₁₄ B-type crystal structure,
The grain boundary phase comprises rare earth elements in _a molar ratio of _Nd :Pr:Ce:La:R ¹ =(1- _xb - _yb - _zb - _{wb ) :} and wherein said z, said z _m and said z _b have a relationship of z _m < z < z _b ;
Rare earth magnet.
<2> The rare earth magnet according to <1>, wherein ^R2 is Nd.
<3> The rare earth magnet according to <1> or < ² >, wherein M2 is at least one element selected from the group consisting of Cu, Al and Co.
<4> The rare earth magnet according to any one of <1> to <3>, wherein ^M2 is Cu.
<5> The rare earth magnet according to any one of <1> to <4>, wherein z satisfies 0.100≦z≦0.150.
<6> The rare earth magnet according to any one of <1> to <5>, wherein x satisfies 0.250≦x≦0.350.
<7> The rare earth magnet according to any one of <1> to <6>, wherein the main phase has an average particle size of 1 to 1000 nm.
<8> (Nd _(1-x-y-z-w) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-p-q-r-stu)} Co _q B _{r Gas} Cu _t M ¹ _u (R ¹ is one or more rare earth elements other than Nd, Pr, Ce, and La; M ¹ is one or more selected from the group consisting of Al, Au, Ag, Zn, In, and Mn; elements and unavoidable impurity elements,
p, q, r, s, t, and u in atomic %,
5.0≦p≦20.0,
0≤q≤8.0,
4.0≦r≦6.5,
0≤s≤0.5,
0≤t≤0.5, and 0≤u≤2.0
and
x, y, z, and w, in molar ratios,
0.200≦x≦0.400,
0≤y≤0.100,
0.100≦z≦0.200, and 0≦w≦0.100
preparing a magnetic ribbon or magnetic powder having a composition of ), and hot-compressing the magnetic ribbon or the magnetic powder to obtain a compact,
A method for producing a rare earth magnet, comprising:
<9> The method according to <8>, wherein the magnetic ribbon or the magnetic powder is compressed in a magnetic field to obtain a compact.
<10> The method according to <8> or <9>, wherein the magnetic ribbon or the magnetic powder is prepared by a strip casting method or an HDDR method.
<11> The method according to <8> or <9>, wherein the magnetic ribbon or the magnetic powder is prepared by a liquid quenching method.
<12> The method according to any one of <8> to <11>, further comprising subjecting the molded body to plastic working in a hot state to obtain a plastically deformed body.
<13> (R ² _a R ³ _b M ² _(1-a-b) ) _v (R ² is one or more elements selected from the group consisting of Nd, Pr, Pm, Sm, Eu, and Gd, R ³ is one or more rare earth elements other than R ² , and M ² is alloyed with R ² and R ³ to increase the melting point of R ² _a R ³ _b M ² _(1-ab) to R ² one or more alloying elements and unavoidable impurity elements that lower the melting point of , and a and b are 0.50 ≤ a ≤ 0.80 and 0 ≤ b ≤ 0.10, respectively) preparing a modified material containing an alloy with a composition
bringing the molded body and the modifier into contact with each other to obtain a contact body; and heat-treating the contact body to allow the melt of the modifier to permeate the interior of the molded body;
The method according to any one of <8> to <11>, comprising
<14> (R ² _a R ³ _b M ² _(1-a-b) ) _v (R ² is one or more elements selected from the group consisting of Nd, Pr, Pm, Sm, Eu, and Gd, R ³ is one or more rare earth elements other than R ² , and M ² is alloyed with R ² and R ³ to increase the melting point of R ² _a R ³ _b M ² _(1-ab) to R ² one or more alloying elements and unavoidable impurity elements that lower the melting point of , and a and b are 0.50 ≤ a ≤ 0.80 and 0 ≤ b ≤ 0.10, respectively) preparing a modified material containing an alloy with a composition
bringing the plastically deformable body and the modifying material into contact with each other to obtain a contacting body, and heat-treating the contacting body to allow the melt of the modifying material to permeate the inside of the plastically deforming body;
The method according to <12>, comprising
<15> The method according to any one of <8> to <14>, wherein R ² is Nd.
<16> The method according to any one of <8> to <15>, wherein ^M2 is one or more elements selected from the group consisting of Cu, Al and Co.
<17> The method according to any one of <8> to <16>, wherein ^M2 is Cu.
<18> The method according to any one of <8> to <17>, wherein z is 0.100≦z≦0.150.
<19> The method according to any one of <8> to <18>, wherein x is 0.250≦x≦0.350.

According to the present disclosure, by coexisting Nd, Pr, and La in the rare earth magnet, it is possible to provide a rare earth magnet that suppresses a decrease in coercive force at high temperatures, and a method for producing the same.

FIG. 1 is a schematic diagram showing an example of the structure of the rare earth magnet of the present disclosure. FIG. 2 is a schematic diagram showing an example of the structure of a conventional rare earth magnet. FIG. 3 is a schematic diagram illustrating a method of preparing a magnetic ribbon by liquid quenching. FIG. 4 is a schematic diagram illustrating a method of preparing a magnetic ribbon by strip casting. FIG. 5 is a schematic diagram illustrating a method of hot-compressing magnetic powder using a punch and a die. FIG. 6 is a schematic diagram illustrating a method of hot plastic working of a compact using a punch and a die. FIG. 7 is a graph showing the relationship between the type of rare earth element and the lattice constant (a-axis and c-axis) of the R ₂ Fe ₁₄ B phase. FIG. 8 is a schematic diagram showing the crystal structure of the R ₂ Fe ₁₄ B phase at room temperature. FIG. 9 is a schematic diagram showing the crystal structure of the R ₂ Fe ₁₄ B phase at high temperatures.

Hereinafter, embodiments of a rare earth magnet and a method for manufacturing the same according to the present disclosure will be described in detail. It should be noted that the embodiments shown below do not limit the rare earth magnet and the manufacturing method thereof according to the present disclosure.

When a molten metal having the overall composition of an R—Fe—B rare earth magnet solidifies, an R ₂ Fe ₁₄ B phase is formed as a main phase, and an R-rich phase is formed as a grain boundary phase around the main phase. In this specification, unless otherwise specified, the R ₂ Fe ₁₄ B phase means a phase having a crystal structure represented by R ₂ Fe ₁₄ B, and the R-rich phase means a phase having a higher R content than the main phase. It means a phase with a large content ratio.

In R—Fe—B rare earth magnets, the coercive force is improved by 1) increasing the anisotropic magnetic field of the main phase, 2) reducing the grain size of the main phase, and 3) magnetically separating the main phases. . Therefore, it is important to improve the anisotropic magnetic field of the main phase to improve the coercive force. Also, the anisotropic magnetic field of the main phase generally decreases as the temperature of the magnet increases. Therefore, in order to suppress the decrease in coercive force at high temperatures, it is important to suppress the decrease in the anisotropic magnetic field at high temperatures.

Among the R ₂ Fe ₁₄ B phases, the Nd ₂ Fe ₁₄ B phase is excellent at room temperature and exhibits relatively little decrease in anisotropic magnetic field even at high temperatures. Therefore, Nd is often selected as R for R—Fe—B based rare earth magnets. However, due to various circumstances, part of Nd may be replaced with a rare earth element other than Nd. When part of Nd is replaced with Pr, the anisotropic magnetic field is lowered especially at high temperatures. However, even if part of Nd is replaced with Pr, if part of Nd is further replaced with La, the decrease in the anisotropic magnetic field at high temperatures can be suppressed. Although not bound by theory, possible reasons for this will be explained with reference to the drawings as follows.

FIG. 7 is a graph showing the relationship between the type of rare earth element and the lattice constant (a-axis and c-axis) of the R ₂ Fe ₁₄ B phase. It should be noted that the source of FIG. Burzo, Rep. Prog. Phys. , 61 (1998), 1099-1266. FIG. 8 is a schematic diagram showing the crystal structure of the R ₂ Fe ₁₄ B phase at room temperature. FIG. 9 is a schematic diagram showing the crystal structure of the R ₂ Fe ₁₄ B phase at high temperatures. Table 1 summarizes the lattice constants (a-axis and c-axis) of the R ₂ Fe ₁₄ B phase for each type of rare earth element from FIG.

The anisotropic magnetic field of the R ₂ Fe ₁₄ B phase mainly depends on the magnitude of the exchange coupling between R and Fe. As shown in FIGS. 8 and 9, in the R ₂ Fe ₁₄ B phase, as the temperature rises, the crystal lattice shrinks in the a-axis direction and expands in the c-axis direction. When the crystal lattice shrinks in the a-axis direction, the distance between R and Fe is shortened, so the magnitude of exchange coupling increases. However, in conventional R--Fe--B rare earth magnets, fluctuations occur in the electron spins of R and Fe due to temperature rise, and exchange bond size is reduced. As a result, the anisotropy field of the R ₂ Fe ₁₄ B phase is significantly reduced at high temperatures.

As shown in Table 1, the lattice constants of both the a-axis and the c-axis have a relationship of La ₂ Fe ₁₄ B phase>Pr ₂ Fe ₁₄ B phase>Nd ₂ Fe ₁₄ B phase>Ce ₂ Fe ₁₄ B phase. have Therefore, when part of Nd is replaced with Pr and/or La, the distance between R and Fe is extended, but the anisotropy field of the (Nd, Pr, La) ₂ Fe ₁₄ B phase is expected does not drop as much.

When the R of the molten metal having the overall composition of the R—Fe—B rare earth magnet mainly contains Nd and Pr, when the molten metal is solidified, the (Nd, Pr) ₂ Fe ₁₄ B phase is produced, and the main phase is A (Nd, Pr) rich phase is generated as a grain boundary phase around the . At this time, regarding the respective molar ratios of Nd and Pr with respect to the total content of Nd and Pr, the respective molar ratios in the main phase and the respective molar ratios in the grain boundary phase are substantially the same.

On the other hand, when the R of the molten metal having the overall composition of the R—Fe—B rare earth magnet mainly contains Nd, Pr, and La, the (Nd, Pr, La) ₂ Fe ₁₄ B phase is produced. , a (Nd, Pr, La) ₂ Fe ₁₄ B phase is generated as a grain boundary phase around the main phase. As for the molar ratio of Pr to the total content of Nd, Pr and La, the molar ratio of Pr in the main phase and the molar ratio of Pr in the grain boundary phase are substantially the same. However, the molar ratio of La to the total content of Nd, Pr and La is higher in the grain boundary phase than in the main phase. This is because the stability of the crystal lattice is Nd ₂ Fe ₁₄ B>Pr ₂ Fe ₁₄ B>La ₂ Fe ₁₄ B, so when a melt containing Nd, Pr and La solidifies, Nd is mainly This is because La tends to become an element constituting a phase, and La is preferentially discharged to the grain boundary phase. As a result, the Nd content in the (Nd, Pr, La) ₂ Fe ₁₄ B phase increases. Since the anisotropic magnetic field at high temperature is Nd ₂ Fe ₁₄ B phase > Pr ₂ Fe ₁₄ B phase > La ₂ Fe ₁₄ B phase, the molar ratio of Nd in the (Nd, Pr, La) ₂ Fe ₁₄ B phase is When is high, the entire rare earth magnet can suppress a decrease in the anisotropic magnetic field at high temperatures.

When R contains a small amount of Ce in addition to Nd, Pr, and La, a (Nd, Pr, Ce, La) ₂ Fe ₁₄ B phase is produced as the main phase, and grains are formed around the main phase. A (Nd, Pr, Ce, La) ₂ Fe ₁₄ B phase is produced as an interfacial phase. And the molar ratio of Ce to the total content of Nd, Pr, Ce and La is slightly higher in the grain boundary phase than in the main phase. This is because the stability of the crystal lattice is Nd ₂ Fe ₁₄ B phase > Pr ₂ Fe ₁₄ B phase > Ce ₂ Fe ₁₄ B phase > La ₂ Fe ₁₄ B phase. This is because, when the molten metal containing is solidified, Nd tends to become an element constituting the main phase, and Ce is also preferentially discharged into the grain boundary phase, though not as much as La. Therefore, in the (Nd, Pr, Ce, La) ₂ Fe ₁₄ B phase, the Nd content is increased, and the decrease in the anisotropic magnetic field at high temperatures can be suppressed in the rare earth magnet as a whole. In addition, as described above, the lattice constant of the a-axis has a relationship of La ₂ Fe ₁₄ B phase>Pr ₂ Fe ₁₄ B phase>Nd ₂ Fe ₁₄ B phase>Ce ₂ Fe ₁₄ B phase. When the moieties are replaced with Ce, the distance between R and Fe is reduced, which contributes to suppressing the decrease in the anisotropic magnetic field.

Furthermore, since there is a large difference in lattice constant between the La ₂ Fe ₁₄ B phase and the Nd ₂ Fe ₁₄ B phase, substituting a portion of Nd with La increases the distortion of the crystal lattice. However, the lattice constant of the Pr ₂ Fe ₁₄ B phase is between the lattice constant of the La ₂ Fe ₁₄ B phase and the lattice constant of the Nd ₂ Fe ₁₄ B phase. When the portion is replaced with La and Pr, strain is relaxed by Pr, which contributes to suppressing a decrease in the anisotropic magnetic field.

Constituent requirements of the rare earth magnet according to the present disclosure and the method for producing the same based on the matters described above will now be described.

《Rare earth magnet》
First, the constituent elements of the rare earth magnet of the present disclosure will be described.

<Overall composition>
The overall composition of the rare earth magnet of the present disclosure has the formula (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-pqrstu )} Co _q B _{r Gas Cut M 1 u ·} ⁽ _R ² _a R ³ _b M ² _(1-ab) ) _v . A rare earth magnet of the present disclosure has a main phase and a grain boundary phase existing around the main phase. "Overall composition" means the composition of the entire rare earth magnet including the main phase and the grain boundary phase.

The rare earth magnet of the present disclosure has (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _(100-pqrstu) Co _q B It is based on ^a _{rare earth magnet} represented by _rGasCutM1u . The rare earth magnet of the present disclosure may optionally be impregnated with a modifier containing an alloy represented by R ² _a R ³ _b M ² _(1-ab) in this base rare earth magnet. When the modifier is impregnated, the base rare earth magnet is a rare earth magnet precursor. The function of the modifier will be described later.

In the formula representing the overall composition of the rare earth magnet of the present disclosure, (R ² _a R ³ _b M ² _(1-ab) ) _v represents the composition derived from the modifier. When no modifier is permeated, v=0 and the overall composition of the rare earth magnet of the present disclosure is (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{( 100-pqrstu)} Co _q B _r Ga _s Cu _t M ¹ _u . On the other hand, when the modifier is permeated, v is a non-zero positive value, and the overall composition of the rare earth magnet of the present disclosure is (Nd _(1-x-y-zw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-pqrstu) Co qBrGasCut} M _{1 u} (R ² _a R ³ _b M ² ( ¹ _{-ab) ) v} is represented by

where Nd is neodymium, Pr is praseodymium, Ce is cerium, La is lanthanum, and ^R1 is one or more rare earth elements other than Nd, Pr, Ce, and La. Fe is iron, Co is cobalt, B is boron, Ga is gallium, and Cu is copper. M1 is ^one or more elements selected from the group consisting of Al, Au, Ag, Zn, In, and Mn, and unavoidable impurity elements. Al is aluminum, Au is gold, Ag is silver, Zn is zinc, In is indium, and Mn is manganese. ^R2 is one or more elements selected from the group consisting of Nd, Pr, Pm, Sm, Eu, and Gd. Nd is neodymium, Pr is praseodymium, Pm is promethium, Sm is samarium, Eu is eurobium and Gd is gadolinium. M ² is one or more alloying elements that lower the melting point of R ² _a R ³ _b M ² _(1-a-b) below the melting point of R ² by alloying with R ² and R ³ and unavoidable impurity element.

In this specification, the rare earth elements are the 17 elements of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Sc is scandium, Y is yttrium, La is lanthanum, Ce is cerium, Pr is praseodymium, Nd is neodymium, Pm is promethium, Sm is samarium, Eu is eurobium, Gd is gadolinium, Tb is terbium, Dy is dysprosium, and Ho is Holmium, Er is erbium, Tm is thulium, Yb is ytterbium, and Lu is ruthenium. Among these, Sc, Y, La, and Ce are light rare earth elements. Pr, Nd, Pm, Sm, Eu, and Gd are middle rare earth elements. Tb, Dy, Ho, Er, Tm, Yb, and Lu are heavy rare earth elements. In general, heavy rare earth elements are highly rare, and light rare earth elements are relatively rare. The rarity of the medium rare earth elements is between the heavy rare earth elements and the light rare earth elements.

Next, p, q, r, s, t, u, and v, and x, y, z, w, a, and b are described.

p, q, r, s, t, and u indicate the following contents of rare earth magnets, respectively. p is the total content of Nd, Pr, Ce, La, and ^R1 , q is the content of Co, r is the content of B, s is the content of Ga, and t is Cu and u is the content of ^M1 . Also, v indicates the amount of penetration of the alloy in the modifier into the rare earth magnet precursor. That is, v represents the total content of R ² , R ³ and M ² . The values of p, q, r, s, t, u, and v are each atomic %.

The values of x, y, z, and w are the following molar ratios (content ratios) of the rare earth magnet, respectively. x indicates the molar ratio of Pr to the total content of Nd, Pr, Ce, La and ^R1 . y indicates the molar ratio of Ce to the total content of Nd, Pr, Ce, La and ^R1 . z indicates the molar ratio of La to the total content of Nd, Pr, Ce, La and ^R1 . w indicates the molar ratio of ^R1 to the total content of Nd, Pr, Ce, La and ^R1 . The values of a and b are the following molar ratios (content ratios) of the modifier, respectively. a indicates the molar ratio of R ² to the total content of R ² , R ³ and M ² . b indicates the molar ratio of R ³ to the total content of R ² , R ³ and M ² .

The constituent elements of the rare earth magnet represented by the above formula will be explained below.

<Nd>
Nd is an essential major component of the rare earth magnets of the present disclosure. A portion of Nd in the rare earth magnets of the present disclosure is replaced with Pr and La. Also, a portion of Nd in the rare earth magnets of the present disclosure is optionally replaced with Ce and ^R1 . The molar ratio of Nd in the rare earth magnet is expressed as 1-xyzw with respect to the total content of Nd, Pr, Ce, La and ^R1 .

<Pr>
Pr is an essential component of the rare earth magnets of the present disclosure. Even if a portion of Nd in the rare earth magnet of the present disclosure is replaced with Pr, the decrease in magnetization is relatively small both at room temperature and at high temperature. On the other hand, when a portion of Nd in the rare earth magnet of the present disclosure is replaced with Pr, the anisotropy field of the main phase is reduced, especially at high temperatures. In order to suppress the decrease in the anisotropic magnetic field at high temperatures, part of the Nd in the rare earth magnet of the present disclosure is further replaced with La. As described above, utilizing the fact that the lattice constant value of the Pr ₂ Fe ₁₄ B phase is between the lattice constant value of the La ₂ Fe ₁₄ B phase and the lattice constant value of the Nd ₂ Fe ₁₄ B phase, It suppresses the harmful effects of the large difference in lattice constant between the La ₂ Fe ₁₄ B phase and the Nd ₂ Fe ₁₄ B phase.

If the molar ratio x of Pr with respect to the total content of Nd, Pr, Ce, La, and ^R1 is 0.200 or more, the molar ratio of La is not relatively excessive, and in the crystal lattice of the main phase R and Fe are not separated excessively, and the strain in the crystal lattice is small. As a result, a decrease in the anisotropic magnetic field of the main phase can be suppressed, especially at high temperatures. From this point of view, x may be 0.220 or greater, 0.240 or greater, 0.250 or greater, 0.260 or greater, or 0.280 or greater. On the other hand, if the molar ratio x of Pr to the total content of Nd, Pr, Ce, La, and ^R1 is 0.400 or less, the molar ratio of La is not relatively too small, and the composition of the rare earth magnet is At the time of solidification of the molten metal, a large amount of La is preferentially discharged into the grain boundary phase, and the molar ratio of Nd in the main phase increases. As a result, a decrease in the anisotropic magnetic field of the main phase can be suppressed, especially at high temperatures. From this point of view, x may be 0.380 or less, 0.360 or less, 0.350 or less, 0.340 or less, 0.335 or less, or 0.330 or less.

<La>
La is an essential component of the rare earth magnets of the present disclosure. As described above, even if part of Nd is replaced with Pr, further replacing part of Nd with La can suppress the decrease in the anisotropic magnetic field of the main phase at high temperatures.

If the molar ratio z of La to the total content of Nd, Pr, Ce, La, and ^R1 is 0.100 or more, a large amount of La preferentially exists in the grain boundary phase during solidification of the molten metal having the composition of the rare earth magnet. , increasing the molar ratio of Nd in the main phase. As a result, a decrease in the anisotropic magnetic field of the main phase can be suppressed, especially at high temperatures. From this point of view, z may be 0.110 or greater, 0.115 or greater, or 0.120 or greater. On the other hand, if the molar ratio z of La to the total content of Nd, Pr, Ce, La, and ^R1 is 0.200 or less, R and Fe are not excessively separated in the crystal lattice of the main phase, and the crystal The strain in the lattice is also small. From this point of view, z may be 0.190 or less, 0.170 or less, 0.150 or less, 0.130 or less, or 0.125 or less.

〈Ce〉
Ce is a component that may optionally be contained in the rare earth magnets of the present disclosure. As described above, during the solidification of the molten metal having the composition of the rare earth magnet, Ce is preferentially discharged to the grain boundary phase, and the molar ratio of Nd increases in the main phase. As a result, it contributes to suppressing a decrease in the anisotropic magnetic field of the main phase, especially at high temperatures. On the other hand, since the lattice constant of the Ce ₂ Fe ₁₄ B phase is very small as described above, the difference between the lattice constant of the Nd ₂ Fe ₁₄ B phase and the lattice constant of the Nd 2 Fe 14 B phase is large. There is little risk of causing strain and, as a result, reducing the anisotropic magnetic field of the main phase.

Even a very small amount of Ce contributes to suppressing a decrease in the anisotropic magnetic field of the main phase. It is substantially recognized that if the molar ratio y of Ce to the total content of Nd, Pr, Ce, La, and ^R1 is 0.005 or more, the decrease in the anisotropic magnetic field of the main phase is suppressed. can. From this point of view, y may be 0.010 or greater, 0.020 or greater, or 0.030 or greater. On the other hand, if the molar ratio y of Ce to the total content of Nd, Pr, Ce, La and ^R1 is 0.100 or less, the main phase is less likely to be distorted. From this point of view, y may be 0.080 or less, 0.060 or less, 0.050 or less, or 0.045 or less. Note that Ce may not be contained in the rare earth magnet of the present disclosure, and y is 0 in that case.

<R ¹ >
R ¹ is one or more rare earth elements other than Nd, Pr, Ce, and La. It is difficult to eliminate rare earth elements ^R1 other than Nd, Pr, Ce, and La from the raw materials of Nd, Pr, Ce, and La. However, when the value of the molar ratio w of R ¹ is 0 to 0.10, the properties of the rare earth magnets of the present disclosure may be considered to be substantially the same as when the value of y is 0.

Since excessively increasing the purity of raw materials leads to an increase in manufacturing costs, the value of w is 0.010 or more, 0.020 or more, 0.030 or more, 0.040 or more, or 0.050 or more. It's okay. On the other hand, the value of w is preferably as low as possible, and may be 0.090 or less, 0.080 or less, 0.070 or less, or 0.060 or less, as long as it does not increase the manufacturing cost.

<Total content of Nd, Pr, Ce, La, and ^R1 >
If the total content p of Nd, Pr, Ce, La, and ^R1 is 5.0 atomic % or more, the main phase represented by ₍ Nd, Pr, Ce, La, ^R1 ) _2Fe14B is easily generated. From this point of view, p may be 7.0 atomic % or more, 9.0 atomic % or more, 11.0 atomic % or more, or 13.0 atomic % or more. On the other hand, when p is 20.0 atomic % or less, the grain boundary phase content (volume fraction) does not become excessive. From this point of view, it may be 19.0 atomic % or less, 18.0 atomic % or less, or 17.0 atomic % or less.

<B>
B affects the content of the main phase and the content of the magnetic phase containing Fe in the grain boundary phase. If the B content is too low, the main phase represented by (Nd, Pr, Ce, La) ₂ Fe ₁₄ B will be difficult to generate. When the content r of B is 4.0 atomic % or more, the main phase represented by (Nd, Pr, Ce, La) ₂ Fe ₁₄ B is not difficult to be generated. From this point of view, r may be 4.5 atomic % or more, 5.0 atomic % or more, or 5.5 atomic % or more. On the other hand, when the B content r is excessive, magnetic phases containing Fe such as the RFe ₄ B ₄ phase are likely to be generated in the grain boundary phase. If r is 6.5 atomic % or less, it is difficult to generate a large amount of α-Fe phase. From this point of view, r may be 6.3 atomic % or less or 6.0 atomic % or less.

〈Co〉
Co is an element that can be substituted for Fe in the main phase and grain boundary phase. In this specification, when Fe is described, part of Fe can be replaced with Co. For example, part of Fe in the (Nd, Ce, La) ₂ Fe ₁₄ B phase is replaced with Co to form the (Nd, Ce, La) ₂ (Fe, Co) ₁₄ B phase. Also, the magnetic phase containing Fe in the grain boundary phase (R ₂ Fe ₁₇ phase, etc.) becomes a magnetic phase (R ₂ (Fe, Co) ₁₇ phase, etc.) in which a part of the Fe is substituted with Co.

By substituting a part of Fe with Co in this way, the Curie point of each phase is improved. If the Curie point is not desired to be improved, Co may be omitted, and the inclusion of Co is not essential. When the Co content q is 0.5 atomic % or more, the Curie point is substantially improved. From the viewpoint of improving the Curie point, it may be 1.0 atomic % or more, 2.0 atomic % or more, 3.0 atomic % or more, or 4.0 atomic % or more. On the other hand, since Co is expensive, from an economical point of view, the Co content q may be 8.0 atomic % or less, 7.0 atomic % or less, or 0.6 atomic % or less.

<Ga>
Ga is an element that lowers the melting point of the grain boundary phase and may optionally be contained in the rare earth magnet of the present disclosure. When a magnetic ribbon or the like is obtained by a liquid quenching method or the like and a compact is obtained from the magnetic ribbon or the like, and/or a plastically deformed compact is obtained from the compact, the melting point of the grain boundary phase is lowered by the inclusion of Ga. This contributes to the improvement of mold life, etc. From this point of view, the Ga content s may be 0 atomic % or more, 0.1 atomic % or more, 0.2 atomic % or more, or 0.3 atomic % or more, and 0.5 atomic % or less or 0 .4 atomic % or less. The molded body and the plastic deformation body will be described later.

<Cu>
Cu is an element that lowers the melting point of the grain boundary phase and may optionally be contained in the rare earth magnet of the present disclosure. When a magnetic ribbon or the like is obtained by a liquid quenching method or the like and a compact is obtained from the magnetic ribbon or the like, and/or a plastically deformed compact is obtained from the compact, the melting point of the grain boundary phase is lowered by the inclusion of Cu. This contributes to the improvement of mold life, etc. From this point of view, the Cu content t may be 0 atomic % or more, 0.1 atomic % or more, 0.2 atomic % or more, or 0.3 atomic % or more, and 0.5 atomic % or less or 0 .4 atomic % or less. The molded body and the plastic deformation body will be described later.

< ^M1 >
M1 can be contained within ^a range that does not impair the properties of the rare earth magnet of the present disclosure. ^M1 may contain unavoidable impurity elements. Unavoidable impurity elements are impurity elements contained in the raw materials of rare earth magnets, or impurity elements mixed in during the manufacturing process. Impurity elements that increase costs. Impurity elements and the like that are mixed in during the manufacturing process include elements that are contained within a range that does not affect the magnetic properties due to manufacturing circumstances.

Elements that can be contained within a range that does not impair the properties of the rare earth magnet of the present disclosure include Al, Au, Ag, Zn, In, and Mn.

Al, Zn, In, Au, and Ag lower the melting point of the grain boundary phase present inside the magnetic ribbon obtained by the liquid quenching method or the like. This is advantageous in improving the life of the mold when obtaining a molded article from a magnetic ribbon or magnetic powder and/or when obtaining a plastically deformed article from a molded article, but the inclusion of these elements is not essential. do not have. These elements do not substantially affect the magnetic properties if the content of M1 is below the ^upper limit. These elements may be regarded as unavoidable impurity elements from the viewpoint of magnetic properties. The molded body and the plastic deformation body will be described later.

Mn replaces part of Fe in the (Nd, Ce, La) ₂ Fe ₁₄ B phase and contributes to stabilization of the (Nd, Ce, La) ₂ Fe ₁₄ B phase.

^If the content u of M1 is 2.0 atomic % or less, the magnetic properties of the rare earth magnet of the present disclosure are not impaired. From this point of view, the content u of M ¹ may be 1.5 atomic % or less, 1.0 atomic % or less, or 0.5 atomic %.

Even if M ¹ does not contain Al, Au, Ag, Zn, In, and Mn, the unavoidable impurity elements cannot be completely eliminated, so the lower limit of the content u of M ¹ is 0.05 atomic % , 0.10 atomic %, or 0.20 atomic %, there is no practical problem.

When M ¹ is two or more elements, the content u of M ¹ is the total content of each of those elements.

Each of the values of p, q, r, s, t, and u explained so far are equivalent to those of a normal R--Fe--B rare earth magnet.

〈Fe〉
Fe is the remainder of Nd, Pr, Ce, La, R ¹ , Co, B, Ga, Cu, and M ¹ explained so far, and the Fe content (atomic %) is (100-pq -rstu). When p, q, r, s, t, and u are within the ranges described above, a main phase and a grain boundary phase are obtained.

<R ² , R ³ , and M ² >
Formula representing the overall composition of the rare earth magnet of the present disclosure (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-pqrstu )} Co _q B _{r Gas Cut M 1 u (} ^R ₂ ^a _R ³ _b M ² _(1-a-b) ) in _v , (R ² _a R ³ _b M ² _(1-a-b) ) _v represents the composition derived from the modifier. Also, R ² _a R ³ _b M ² _(1-ab) represents the composition of the alloy in the modifier. Further, v indicates the permeation amount (atomic %) of the modifier with respect to the rare earth magnet (rare earth magnet precursor) before permeation of the modifier.

^R2 is one or more elements selected from the group consisting of Nd, Pr, Pm, Sm, Eu, and Gd. Also, R ³ is one or more rare earth elements other than R ² . M2 is one or more alloying elements and unavoidable impurity elements that, by being alloyed with ^R2 and R3 ^, make the melting point of the alloy in the modifier lower ^than the melting point of ^R2 . An unavoidable impurity element is an impurity element such as an impurity element contained in a raw material, which cannot be avoided, or whose avoidance causes a significant increase in manufacturing cost.

Regarding R ² and M ² , Nd is preferable as R ² from the viewpoint of facilitating the formation of a eutectic alloy, and M ² is a superior element selected from the group consisting of Cu, Al, and Co. is preferred, and Cu is particularly preferred as ^M2 . Also, Cu, Al, and Co have little adverse effect on the magnetic properties of rare earth magnets.

The composition of the alloy in the modifier may be appropriately determined so that the melting point of the alloy in the modifier is lower than the melting point of ^R2 . The melting point of the alloy in the modifier depends on the molar ratio a of ^R2 of the alloy in the modifier. In order to lower the melting point of the alloy in the modifier below the melting point of ^R2 , the molar ratio a of ^R2 may be 0.50 or more, 0.55 or more, or 0.60 or more. 0.80 or less, 0.75 or less, or 0.70 or less.

The main rare earth element contained in the alloy in the modifier is ^{R2 ,} but it is difficult to completely eliminate the rare earth element R3 other than ^R2 . However, if the value of the molar ratio b of R ³ is 0 to 0.10, the properties as a modifier can be considered to be substantially the same as when the value of b is 0.

Ideally, the value of b is close to 0, but the value of b may be 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more. On the other hand, the value of b is preferably low as long as it does not increase the manufacturing cost, and may be 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, or 0.06 or less. .

The coercive force can be further improved by optionally impregnating the base rare earth magnet (rare earth magnet precursor) with a modifier. On the other hand, if the amount of permeation of the modifier is excessive, the magnetization will decrease due to the ^M2 in the modifier. For this reason, the permeation amount of the modifying material may be appropriately determined according to the balance between the improvement in coercive force and the reduction in magnetization. The permeation amount v of the modifier to the rare earth magnet (rare earth magnet precursor) before the modifier is permeated is 0 atomic % or more, 1.0 atomic % or more, 3.0 atomic % or more, or 5.0 atoms. % or more, and may be 10.0 atomic % or less, 8.0 atomic % or less, or 6.0 atomic % or less. Note that 0 for y means that the modifier does not permeate.

<Main phase and grain boundary phase>
The structure of the rare earth magnet of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the structure of the rare earth magnet of the present disclosure. FIG. 2 is a schematic diagram showing an example of the structure of a conventional rare earth magnet. Both FIGS. 1 and 2 show the case where the modifier is not permeated.

As shown in FIG. 1 , the rare earth magnet 10 of the present disclosure has a main phase 11 and a grain boundary phase 12 . The grain boundary phase 12 exists around the main phase 11 .

The main phase 11 has a (Nd, Pr, Ce, La, R ¹ ) ₂ (Fe, Co) ₁₄ B type crystal structure (hereinafter referred to as “(Nd, Pr, Ce, La, R ¹ ) ₂ ( Fe, Co) ₁₄ B" phase). “(Nd, Pr, Ce, La, R ¹ ) ₂ (Fe, Co) ₁₄ B type crystal structure” means that in the crystal, M ¹ and unavoidable impurities and a small amount of elements constituting the modifier It means that it may contain

The grain boundary phase 12 is a (Nd, Pr, Ce, La, R ¹ ) rich phase. The (Nd, Pr, Ce, La, R ¹ )-rich phase is a phase containing more Nd, Pr, Ce, La, and R ¹ than the main phase 11 . Since the main phase 11 is magnetically divided by the grain boundary phase 12, the coercive force is improved.

The main phase 11 contains rare earth elements in a molar ratio of Nd:Pr:Ce:La:R ¹ =(1- _xm - _ym - _zm - _wm ): _xm : _ym : _zm : _wm . have. In addition, the grain boundary phase 12 has _a molar ratio of Nd:Pr:Ce:La:R ¹ =(1- _xb -yb- _zb - _wb ): _xb : _yb : _zb : _wb It has rare earth elements.

(Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-p-q-r-stu)} Co _q B _{r Gas Cu t M} ¹ When the melt having the composition represented by _u solidifies, it produces a main phase 11 and a grain boundary phase 12 . At this time, La and Ce, particularly La, are preferentially discharged to the grain boundary phase 12 as described above. Therefore, when the molar ratio of La in the rare earth magnet 10 of the present disclosure is z, the molar ratio of La in the main phase 11 is _zm , and the molar ratio of La in the grain boundary phase 12 is _zb , then _zm <z< _zb have a relationship of The molar ratio z of La in the rare earth magnet 10 of the present disclosure may be considered equal to the molar ratio of La in the molten metal.

Further, as described above, when the molten metal solidifies, Ce is preferentially discharged to the grain boundary phase 12, though not as much as La. Therefore, if y is the molar ratio of Ce in the rare earth magnet 10 of the present disclosure, y _m is the molar ratio of Ce in the main phase 11, and y _b is the molar ratio of Ce in the grain boundary phase 12, y _m <y<y _b have a relationship of The molar ratio y of Ce in the rare earth magnet 10 of the present disclosure may be considered equal to the molar ratio of Ce in the molten metal.

Regarding the rare earth magnet 10 of the present disclosure described so far, for example, (Nd _0.500 Pr _0.335 Ce _0.045 La _0.012 ) _13.11 Fe _80.43 B _5.99 Ga _0.37 Cu ₀ The case when the molten metal having the composition represented by _.10 is solidified will be described with reference to FIG. In order to simplify the explanation, the case where R ¹ , Co, and M ¹ are not contained will be explained. Ga and Cu are contained in the main phase 11 and the grain boundary phase 12 in minute amounts.

When the molten metal of this example solidifies, a rare earth magnet 10 of the present disclosure is obtained having the same composition as the molten metal. That is, the overall composition of the rare earth magnet 10 of the present disclosure is (Nd _0.500 Pr _0.335 Ce _0.045 La _0.120 ) _13.11 Fe _80.43 B _5.99 Ga _0.37 Cu _0.10 is. The rare earth magnet 10 of the present disclosure has the main phase 11 and the grain boundary phase 12 . As shown in FIG. ₁ , the main phase 11 is the _{( Nd0.519Pr0.335Ce0.043La0.103 ) 2Fe14B} phase, and the grain _boundary phase ₁₂ is the ( _{Nd0.485Pr0 .335} Ce _0.047 La _0.133 ) rich phase. From this, the molar ratio z of La in the rare earth magnet 10 of the present disclosure is 0.120, the molar ratio _zm of La in the main phase 11 is 0.103, and the molar ratio z of La in the grain boundary phase 12 _b is 0.133 and has a relationship of z _m <z<z _b . Further, the molar ratio y of Ce in the rare earth magnet 10 of the present disclosure is 0.045, the molar ratio _ym of Ce in the main phase 11 is 0.043, and the molar ratio _yb of Ce in the grain boundary phase 12 is 0.047 and has a relationship of y _m <y<y _b . On the other hand, the Nd molar ratio in the rare earth magnet 10 of the present disclosure is 0.500, the Nd molar ratio in the main phase 11 is 0.519, and the Nd molar ratio in the grain boundary phase 12 is 0.485. , the Nd molar ratio is high in the main phase 11 which greatly affects the anisotropic magnetic field at high temperatures.

For comparison with FIG. 1, for a conventional rare earth magnet, for example, Nd, Pr, and La do not coexist (Nd _0.750 Pr _0.250 ) _13.11 Fe _80.43 B _5.99 Ga _0.37 Cu FIG. 2 is used to explain when the molten metal having the composition represented by _0.10 solidifies.

When the molten metal in this example solidifies, a conventional rare earth magnet 50 is obtained having the same composition as the molten metal. That is, the overall composition of the conventional rare earth magnet 50 is (Nd _0.750 Pr _0.250 ) _13.11 Fe _80.43 B _5.99 Ga _0.37 Cu _0.10 . A conventional rare earth magnet 50 has a main phase 51 and a grain boundary phase 52 . As shown in FIG. 2, the main phase 51 is the (Nd _0.750 Pr _0.250 ) ₂ Fe ₁₄ B phase, and the grain boundary phase 12 is the (Nd _0.750 Pr _0.250 ) rich phase. Therefore, when Nd, Pr, and La do not coexist, neither Nd nor Pr is preferentially discharged into the grain boundary phase. Therefore, the molar ratio of Nd in the main phase and the molar ratio of Nd in the grain boundary phase are the same at 0.75. Also, the molar ratio of Pr in the main phase and the molar ratio of Pr in the grain boundary phase are the same at 0.25.

The rare earth magnet 10 of the present disclosure may or may not be nanocrystallized. Being nanocrystallized means that the main phase 11 is nanocrystallized, and means that the average grain size of the main phase 11 is 1 to 1000 nm. Being nano-crystallized means that the main phase 11 has an average grain size of 1 to 1000 nm. The average particle size of the main phase 11 may be 10 nm or more, 50 nm or more, or 100 nm or more, and may be 900 nm or less, 700 nm or less, 500 nm or less, or 300 nm or less. In this specification, unless otherwise specified, the “average particle size” means the average of the projected area circle equivalent diameters of the main phase 11 .

"Production method"
Next, a method for manufacturing the rare earth magnet of the present disclosure will be described.

<Preparation of magnetic ribbon or magnetic powder>
(Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-p-q-r-stu)} Co _q B _{r Gas Cu t M} ¹ A magnetic ribbon or magnetic powder having a composition of _u is prepared. Nd, Pr, Ce, La, ^R1 , Fe, Co, B, Ga, Cu, and M1 are the same as the rare earth ^magnets of the present disclosure. Also, p, q, r, s, t, and u, and x, y, z, and w are the same as those described for the rare earth magnets of the present disclosure. If a specific component is worn during the preparation of the magnetic ribbon or magnetic powder or in subsequent steps, it may be possible to allow for that amount.

The method of preparing the magnetic ribbon or magnetic powder is not particularly limited. Methods for preparing the magnetic ribbon or magnetic powder include liquid quenching, strip casting, and HDDR (Hydrogen Disproportion Desorption Recombination). A magnetic ribbon or magnetic powder may be obtained by heat-treating the amorphous ribbon or powder. Liquid quenching is preferable from the viewpoint of nanocrystallization of the rare earth magnet of the present disclosure. By nanocrystallizing the rare earth magnet of the present disclosure, magnetization and coercive force, especially coercive force, can be further improved. Although it is difficult to nanocrystallize the rare earth magnet of the present disclosure using the strip casting method, a large amount of magnetic ribbon or magnetic powder can be prepared relatively easily. When using the magnetic ribbon or magnetic powder obtained by the strip casting method, the average particle size of the main phase of the rare earth magnet of the present disclosure can be 2 to 50 μm. When using the HDDR method, the main phase does not become finer than when using the liquid quenching method, but the rare earth magnet of the present disclosure can be nano-crystallized to some extent. In addition, since the magnetic powder obtained by the HDDR method has anisotropy, it contributes to improving the magnetization of the rare earth magnet of the present disclosure.

The liquid quenching method will be briefly explained. FIG. 3 is a schematic diagram illustrating a method of preparing a magnetic ribbon by liquid quenching. For example, (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-pq -rstu)} An alloy having a composition of Co _q B _r Ga _s Cu _t M ¹ _u is melted by high frequency to obtain a molten metal. This molten metal is injected from a nozzle 60 onto a cooling roll 62 to obtain a magnetic strip 64 . Although FIG. 3 shows the manner in which the magnetic ribbon 64 is obtained, magnetic powder can be obtained depending on the peripheral speed of the cooling roll 62 and the like.

The cooling rate of the molten metal may be appropriately determined so as to nanocrystallize the magnetic ribbon or magnetic powder. The cooling rate of the melt may typically be 1×10 ² K/sec or higher, 1×10 ³ K/sec or higher, or 1×10 ⁴ K/sec or higher, and 1×10 ⁷ K/sec. 1×10 ⁶ K/sec or less, or 1×10 ⁵ K/sec or less.

The melt injection temperature may typically be 1300° C. or higher, 1350° C. or higher, or 1400° C. or higher, and may be 1600° C. or lower, 1550° C. or lower, or 1500° C. or lower.

The peripheral speed of the cooling roll 62 is typically 20 m/s or more, 24 m/s or more, or 28 m/s or more, and 40 m/s or less, 36 m/s or less, or 32 m/s or less. It's okay.

The strip cast method will be briefly explained. FIG. 4 is a schematic diagram illustrating a method of preparing a magnetic ribbon by strip casting. For example, (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-pq -rstu)} An alloy having a composition of Co _q B _{r Gas Cu t M} ¹ _u is melted using a high-frequency furnace 61 or the like to obtain a molten metal 63 . This molten metal 63 is supplied to the chill roll 62 from the end of the tundish 66 . The molten metal 63 is cooled and solidified on the outer periphery of the cooling roll 62 to form the magnetic ribbon 64 . Then, the magnetic ribbon 64 is separated from the cooling roll 62 and recovered by a recovery device (not shown). FIG. 4 shows the manner in which the magnetic ribbon 64 is obtained.

The cooling rate of the molten metal may be appropriately determined so that the magnetic ribbon or the like can be obtained continuously. The cooling rate of the melt may typically be 1×10 ⁰ K/sec or more, 1×10 K/sec or more, 3×10 K/sec or more, or 5×10 K/sec or more, and 9×10 K/sec or less. , 8×10 K/s or less, or 6×10 K/s or less.

The melt injection temperature may typically be 1300° C. or higher, 1350° C. or higher, or 1400° C. or higher, and may be 1600° C. or lower, 1550° C. or lower, or 1500° C. or lower.

The peripheral speed of the cooling roll 62 is typically 1 m/s or more, 5 m/s or more, or 10 m/s or more, and is 18 m/s or less, 16 m/s or less, or 14 m/s or less. It's okay.

The HDDR method will be briefly described. HDDR is a concatenated acronym for Hydrogenation, Disproportionation, Desorption, and Recombination.

The HDDR method is (Nd _{(1- xyzw} ) Pr _x Cey La _z R ¹ _w ) _p Fe _(100-pqrstu) Co _q B _r Ga _s An alloy having a composition of Cu _t M ¹ _u is subjected to HD treatment and DR treatment separately to obtain magnetic powder. Each treatment will be described by simplifying the composition of the alloy to R--Fe--B (where R is a rare earth element). In HD treatment, the R ₂ Fe ₁₄ B phase is decomposed by a disproportionation reaction with hydrogen. In the DR treatment, the R ₂ Fe ₁₄ B phase is obtained by the reverse reaction (recombination reaction) of the disproportionation reaction.

The disproportionation reaction can be represented by a chemical formula as follows.
R2Fe14B _{+ 2H2} →2RH2 ₊ 12Fe _{+ Fe2B}

The recombination reaction is represented by a chemical reaction formula as follows.
2RH2 ₊ 12Fe ₊ Fe2B→ _{R2Fe14B + 2H2}

The temperature of the HD treatment may typically be 750°C or higher, 775°C or higher, 800°C or higher, or 825°C or higher, and 950°C or lower, 925°C or lower, 900°C or lower, 875°C or lower, or 850°C or higher. °C or lower. The hydrogen partial pressure during the HD treatment may typically be 10 kPa or more, 15 kPa or more, 20 kPa or more, or 25 kPa or more, and may be 40 kPa or less, 35 kPa or less, or 30 kPa or less.

The temperature of the DR treatment may typically be 750° C. or higher, 775° C. or higher, 800° C. or higher, or 825° C. or higher, and 950° C. or lower, 925° C. or lower, 900° C. or lower, 875° C. or lower, or 850° C. or higher. °C or lower. The atmosphere during the DR process may typically be a vacuum or an inert gas atmosphere.

<Formation of compact>
A compact is obtained by hot-compressing the magnetic ribbon or magnetic powder. Before hot-compressing the magnetic ribbon, the magnetic ribbon may be pulverized to 10 μm or less.

The temperature at which the magnetic ribbon or magnetic powder is hot-compressed may be any temperature at which a compact can be obtained. It may be a temperature at which a part of the grain boundary phase in the magnetic ribbon or magnetic powder melts. That is, the magnetic ribbon or magnetic powder may be liquid-phase sintered. The atmosphere in which the magnetic ribbon or magnetic powder is hot-pressed is preferably an inert gas atmosphere in order to prevent oxidation of the magnetic ribbon or magnetic powder and the compact. Alternatively, the magnetic powder obtained by pulverizing the magnetic ribbon may be compacted to obtain a compact, and then the compact may be sintered (including liquid phase sintering).

The heating temperature for hot compression of the magnetic ribbon or magnetic powder is typically 550° C. or higher, 570° C. or higher, 600° C. or higher, or 630° C. or higher. °C or lower, 700 °C or lower, or 670 °C or lower.

The pressure when the magnetic ribbon or magnetic powder is hot compressed is typically 200 MPa or more, 300 MPa or more, or 350 MPa or more, and may be 600 MPa or less, 500 MPa or less, or 450 MPa or less. .

The pressing time when hot-compressing the magnetic ribbon or magnetic powder may typically be 1 second or longer, 5 seconds or longer, 20 seconds or longer, or 40 seconds or longer, and 350 seconds or shorter. It may be 250 seconds or less, 150 seconds or less, 100 seconds or less, or 80 seconds or less.

There are no particular restrictions on the method of hot-compressing the magnetic ribbon or magnetic powder, but examples include a method using a die and a punch.

A method using dies and punches will be briefly described. FIG. 5 is a schematic diagram illustrating a method of hot-compressing magnetic powder using a punch and a die. First, the die 70 and the punch 72 are prepared. Punch 72 slides within the cavity of die 70 . A magnetic powder 74 is charged into a cavity surrounded by a die 70 and a punch 72 and pressed by the punch 72 in the direction of the arrow in FIG. Before and/or after charging the magnetic powder 74, the die 70 is heated. The die 70 may be heated during pressurization. Although FIG. 5 shows an aspect in which the magnetic powder 74 is hot-compressed, the magnetic ribbon 64 may be hot-compressed.

Hot compression of the magnetic ribbon or magnetic powder may be performed in a magnetic field. This can impart anisotropy to the rare earth magnet of the present disclosure. Hot compaction in a magnetic field is particularly effective when magnetic ribbons or magnetic powders are prepared by strip casting or HDDR methods. The magnitude of the applied magnetic field may typically be 0.3 T or more, 0.5 T or more, or 1.0 T or more, and 5.0 T or less, 3.0 T or less, or 2 .0T or less. The magnitude of the applied magnetic field may be 1.0 T or more, 2.0 T or more, or 3.0 T or more in the case of a pulse magnetic field, and may be 7.0 T or less, 6.0 T or less, or 5.0 T or less. you can

A compact obtained by hot-pressing a magnetic ribbon or magnetic powder (including a compact hot-pressed in a magnetic field) may be used as the rare earth magnet of the present disclosure, and subsequent steps may be performed. .

<Formation of plastic deformation body>
A magnetic ribbon or magnetic powder may be hot-compressed to obtain a molded body, and then the molded body may be subjected to hot plastic working to obtain a plastically deformed body. This can impart anisotropy to the anisotropic magnet of the present disclosure. Hot plastic working of the compact is particularly effective when the magnetic ribbon or magnetic powder is prepared by liquid quenching. This is because the magnetic ribbon or magnetic powder prepared by the liquid quenching method is nano-crystallized. Also, when a compact is obtained by hot-compressing the magnetic ribbon or magnetic powder in a magnetic field, the compact may be further subjected to hot plastic working to obtain a plastically deformed product.

The rolling reduction during hot plastic working may be appropriately set so as to obtain desired anisotropy. The rolling reduction during hot plastic working is typically 10% or more, 30% or more, 50% or more, or 60% or more, and 75% or less, 70% or less, or 65%. may be:

The temperature during the hot plastic working may be appropriately set so that the compact is not destroyed and crystal grains in the compact are not coarsened. The temperature during hot plastic working may be 650° C. or higher, 700° C. or higher, or 750° C. or higher, and may be 850° C. or lower, 820° C. or lower, or 800° C. or lower.

In order to avoid coarsening of crystal grains in the compact during hot plastic working, the strain rate during hot plastic working should be fast. On the other hand, if the strain rate during hot plastic working is excessively high, the wear of dies, punches, etc. used in hot plastic working becomes noticeable. The strain rate during hot plastic working is typically 0.001/s or more, 0.005/s or more, 0.01/s or more, 0.1/s or more, or 1.0/s or more. s or greater, and may be 10.0/s or less, 5.0/s or less, 3.0/s or less, or 2.0/s or less.

There are no particular restrictions on the method of plastic working the molded article in a hot state, but examples thereof include upsetting and backward extrusion. Here, a method using a die and a punch will be briefly described as an example of a method for hot plastic working of a compact.

FIG. 6 is a schematic diagram illustrating a method of hot plastic working of a compact using a punch and a die. First, the die 70 and the punch 72 are prepared. Punch 72 slides within the cavity of die 70 . A punch 72 is brought into contact with the end face of the molded body 76 , and the molded body 76 is plastically worked while being pressed by the punch 72 to obtain a plastically deformed body 78 . The die 70 is heated before and/or after the punch 72 is brought into contact with the end surface of the compact 76 . The die 70 may be heated during pressurization.

A plastically deformed body obtained by hot plastic working of the molded body may be used as the rare earth magnet of the present disclosure, and subsequent steps may be performed.

<Preparation of modifier>
A modifier containing an alloy having a composition represented by R ² _a R ³ _b M ² _1-ab is prepared. The details of R ² , R ³ and M ² and the details of a and b are the same as those of the rare earth magnet.

An alloy with a composition represented by R ² _a R ³ _b M ² _1-ab is R ² _z R ³ _w M ² _1-zw because M ² is alloyed with R ² and R ³ is lower than that of ^R2 . As a result, the alloy in the reforming material can be melted without excessively increasing the temperature of the heat treatment described later. As a result, the alloy in the modifier can permeate into the molded body and/or the plastically deformed body without coarsening the structure of the molded body and/or the plastically deformed body.

Examples of alloys having compositions represented by R ² _z R ³ _w M ² _1-zw include Nd--Cu alloys, Pr--Cu alloys, Nd--Pr--Cu alloys, Nd--Al alloys, Pr--Al alloys, Nd--Pr--Al alloy, Nd--Co alloy, Pr--Co alloy, Nd--Pr--Co alloy and the like.

The method for producing the modifier is not particularly limited. Examples of methods for manufacturing the reforming material include a casting method and a liquid quenching method. The liquid quenching method is preferable from the viewpoints that there are few impurities such as oxides and that variations in the alloy composition depending on the part of the modifier are small.

The permeation amount of the alloy in the modifier is represented by v (atomic %) in the overall composition formula. Regarding v, the explanation for the rare earth magnet is the same.

<Formation of contact body>
A contact body is obtained by bringing the compact or plastic deformation body and the modifier into contact with each other. As described above, the compact is obtained by hot-compressing a magnetic ribbon or magnetic powder. A magnetic ribbon or magnetic powder may be hot-pressed in a magnetic field. The plastic deformable body is obtained by hot plastic working.

When obtaining the contact body, at least one surface of the molded or plastically deformed body and at least one surface of the modifier are brought into contact with each other. As a result, the melt of the modifier permeates through the contact surface between the compact or plastically deformed body and the modifier.

<Heat treatment>
A rare earth magnet of the present disclosure is obtained by heat-treating the above-mentioned contact body and infiltrating the melt of the modifier into the inside of the molded body or the plastically deformed body. Permeation of the modifier improves the magnetization and coercive force, especially the coercive force, of the rare earth magnet of the present disclosure. This is because the permeation of the modifier promotes magnetic separation between the main phases.

The heat treatment temperature may be appropriately determined so that the melt of the modifier penetrates into the inside of the molded body or plastically deformed body and the coarsening of the structure of the molded body or plastically deformed body is suppressed. The higher the heat treatment temperature, the easier it is for the melt of the modifier to permeate into the compact or plastically deformed body. From this point of view, the heat treatment temperature is preferably 580° C. or higher, more preferably 600° C. or higher, and even more preferably 620° C. or higher. On the other hand, the lower the heat treatment temperature, the easier it is to suppress coarsening of the structure of the compact or plastically deformed body. From this point of view, the heat treatment temperature is preferably 800° C. or lower, more preferably 775° C. or lower, and even more preferably 725° C. or lower.

The heat treatment atmosphere is not particularly limited, but an inert gas atmosphere is preferable from the viewpoint of suppressing oxidation of the compact, the plastically deformed body, and the modifier.

EXAMPLES The rare earth magnet of the present disclosure and the method for producing the same will be described more specifically with reference to examples and comparative examples. It should be noted that the rare earth magnet of the present disclosure and its manufacturing method are not limited to the conditions used in the following examples.

<Preparation of sample>
A molten metal having a composition represented by R _13.11 Fe _80.43 Cu _0.10 B _5.99 Ga _0.37 was liquid quenched to obtain a magnetic ribbon. R is as shown in Tables 2 and 3 below. The liquid quenching conditions were a melt temperature (discharge temperature) of 1450° C. and a roll peripheral speed of 30 m/s. At this time, the cooling rate of the molten metal was 10 ⁶ K/sec. Liquid quenching was performed under an argon gas reduced pressure atmosphere. It was confirmed by observation with a transmission electron microscope (TEM) that the magnetic ribbon was nano-crystallized.

The magnetic ribbon was put into a die and hot-compressed to obtain a compact. As the pressurization and heating conditions, the pressurization force was 400 MPa, the heating temperature was 650° C., and the holding time of the pressurization and heating was 300 seconds.

The molded body was subjected to hot plastic working to obtain a plastically deformed body. The hot plastic working compressed a sample with a height of 15 mm to 4.5 mm. The hot plastic working conditions were a working temperature of 780° C., a strain rate of 0.01/s, and a rolling reduction of 70%. Scanning electron microscopy (SEM) confirmed that the plastically deformed bodies had oriented nanocrystals.

An alloy having a composition represented by Nd _0.7 Cu _0.3 was prepared as a modifier. Nd powder and Cu powder manufactured by Kojundo Chemical Co., Ltd. were weighed, arc-melted, and liquid-quenched to obtain a ribbon.

The plastically deformable body and the reforming material were brought into contact with each other and heat-treated in a heating furnace. The amount of permeation of the modifier was 0 atomic %, 3.7218 atomic %, and 5.3184 atomic % with respect to the plastic deformation body. When the amount of the modifier permeated is 0 atomic %, it means that the plastically deformed body is used as the rare earth magnet without the modifier being permeated into the plastically deformed body. As the heat treatment conditions, the heat treatment temperature was 625° C., and the heat treatment time was 165 minutes.

<evaluation>
Coercive force and remanent magnetization were measured for each sample. For the measurement, a pulse excitation type magnetic property measuring device manufactured by Toei Industry Co., Ltd. (maximum applied magnetic field: 15 T) was used. Both coercivity and remanent magnetization were measured at 23°C, 100°C, 140°C and 160°C. In addition, for the plastically deformed body before permeation of the modifier, component analysis (EDX point analysis) was performed using a scanning transmission electron microscope (STEM), and Pr, Ce, and La of the main phase and grain boundary phase, respectively was measured to obtain _xm , _xb , _ym , _yb , _zm , and _zb .

Tables 3 and 4 show the results. In Table 4, the gradient ΔHc between 23 and 160° C. for the coercive force and the gradient ΔBr between 23 and 160° C. for the residual magnetization are also shown.

From Table 3, for Examples 1 to 5 in which Nd, Pr, and La coexist, z _m <z < _zb , indicating that La is preferentially discharged to the grain boundary phase. It can be understood. As a result, it can be understood that the molar ratio of Nd is increased in the main phase. Further, from Table 4, for Examples 1 to 5 in which Nd, Pr, and La coexist, the absolute value of ΔHc is smaller than Comparative Examples 1 to 8, and the decrease in coercive force at high temperatures can be suppressed. It is understandable that

From the above results, the effects of the rare earth magnet of the present disclosure and the method for producing the same have been confirmed.

10 Rare earth magnet of the present disclosure 11, 51 Main phase 12, 52 Grain boundary phase 50 Conventional rare earth magnet 60 Nozzle 61 High frequency furnace 62 Cool roll 63 Molten metal 64 Magnetic ribbon 66 Tundish 70 Die 72 Punch 74 Magnetic powder 76 Formed body 78 plastic deformation

Claims (19)

The overall composition is (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _(100-pqrstu) Co _q B _r Ga _s Cu _t M ¹ _u (R ² _a R ³ _b M ² _(1-ab) ) _v ,
R ¹ is one or more rare earth elements other than Nd, Pr, Ce, and La;
M ¹ is one or more elements selected from the group consisting of Al, Au, Ag, Zn, In, and Mn and an unavoidable impurity element,
R2 is ^one or more elements selected from the group consisting of Nd, Pr, Pm, Sm, Eu, and Gd, R3 ^is one or more rare earth elements other than ^R2 ,
M ² is one or more alloying elements and unavoidable impurities that lower the melting point of R ² _a R ³ _b M ² _(1-a-b) below the melting point of R ² by alloying with R ² and R ³ is an element,
p, q, r, s, t, u, and v in atomic %,
5.0≦p≦20.0,
0≤q≤8.0,
4.0≦r≦6.5,
0≤s≤0.5,
0≤t≤0.5,
0≦u≦2.0, and
0≤v≤10.0
and
x, y, z, w, a, and b, in molar ratios,
0.200≦x≦0.400,
0≤y≤0.100,
0.100≦z≦0.200,
0≤w≤0.100
0.50≦a≦0.80, and
0≤b≤0.10
and
It has a main phase and a grain boundary phase existing around the main phase,
The main phase contains rare earth elements in a molar ratio of Nd:Pr:Ce:La:R ¹ =(1- _xm - _ym - _zm - _wm ): _xm : _ym : _zm : _wm and having a phase with a (Nd, Pr, Ce, La, R ¹ ) ₂ (Fe, Co) ₁₄ B-type crystal structure,
The grain boundary phase comprises rare earth elements in _a molar ratio of _Nd :Pr:Ce:La:R ¹ =(1- _xb - _yb - _zb - _{wb ) :} and wherein said z, said z _m and said z _b have a relationship of z _m < z < z _b ;
Rare earth magnet. A rare earth magnet according to claim 1, wherein said ^R2 is Nd. ^3. The rare earth magnet according to claim 1, wherein said M2 is one or more elements selected from the group consisting of Cu, Al and Co. A rare earth magnet according to any one of claims 1 to 3, wherein said ^M2 is Cu. The rare earth magnet according to any one of claims 1 to 4, wherein z satisfies 0.100≤z≤0.150. The rare earth magnet according to any one of claims 1 to 5, wherein said x satisfies 0.250≤x≤0.350. The rare earth magnet according to any one of claims 1 to 6, wherein the main phase has an average particle size of 10 nm or more and 900 nm or less . (Nd _(1-xyzw) Pr _x Ce _y La _z R ¹ _w ) _p Fe _{(100-p-q-r-stu)} Co _q B _{r Gas Cu t M} ¹ _u , R ¹ is one or more rare earth elements other than Nd, Pr, Ce, and La; M ¹ is one or more selected from the group consisting of Al, Au, Ag, Zn, In, and Mn; elements and unavoidable impurity elements,
p, q, r, s, t, and u in atomic %,
5.0≦p≦20.0,
0≤q≤8.0,
4.0≦r≦6.5,
0≤s≤0.5,
0≤t≤0.5, and 0≤u≤2.0
and
x, y, z, and w, in molar ratios,
0.200≦x≦0.400,
0≤y≤0.100,
0.100≦z≦0.200, and 0≦w≦0.100
Preparing a magnetic ribbon or magnetic powder having a composition of and hot-compressing the magnetic ribbon or the magnetic powder to obtain a compact,
A method for producing a rare earth magnet, comprising: 9. The method according to claim 8, wherein the magnetic ribbon or the magnetic powder is compressed in a magnetic field to obtain a compact. 10. A method according to claim 8 or 9, wherein said magnetic ribbon or said magnetic powder is prepared by strip casting method or HDDR method. 10. A method according to claim 8 or 9, wherein said magnetic ribbon or said magnetic powder is prepared by a liquid quenching method. 12. The method according to any one of claims 8 to 11, further comprising subjecting the molded body to hot plastic working to obtain a plastically deformed body. (R ² _a R ³ _b M ² _(1-a-b) ) _v , wherein R ² is one or more elements selected from the group consisting of Nd, Pr, Pm, Sm, Eu, and Gd; R ³ is one or more rare earth elements other than R ² , and M ² is alloyed with R ² and R ³ to increase the melting point of R ² _a R ³ _b M ² _(1-ab) to R ² one or more alloying elements and unavoidable impurity elements that lower the melting point of preparing a modified material containing the alloy;
bringing the molded body and the modifier into contact with each other to obtain a contact body; and heat-treating the contact body to allow the melt of the modifier to permeate the interior of the molded body;
A method according to any one of claims 8 to 11, comprising (R ² _a R ³ _b M ² _(1-a-b) ) _v , wherein R ² is one or more elements selected from the group consisting of Nd, Pr, Pm, Sm, Eu, and Gd; R ³ is one or more rare earth elements other than R ² , and M ² is alloyed with R ² and R ³ to increase the melting point of R ² _a R ³ _b M ² _(1-ab) to R ² one or more alloying elements and unavoidable impurity elements that lower the melting point of preparing a modified material containing the alloy;
bringing the plastically deformable body and the modifying material into contact with each other to obtain a contacting body, and heat-treating the contacting body to allow the melt of the modifying material to permeate the inside of the plastically deforming body;
13. The method of claim 12, comprising: 15. The method of claim 13 or 14 , wherein said ^R2 is Nd. The method according to any one of claims 13 to 15 , wherein said ^M2 is one or more elements selected from the group consisting of Cu, Al and Co. A method according to any one of claims 13 to 15 , wherein said ^M2 is Cu. A method according to any one of claims 8 to 17, wherein said z is 0.100≤z≤0.150. A method according to any one of claims 8 to 18, wherein said x is 0.250≤x≤0.350.

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