JP2020107849A - Rare earth magnet and method for manufacturing the same - Google Patents

Abstract

To provide a rare earth magnet arranged so that the decrease in coercive force at a high temperature can be suppressed in particular, and a method for manufacturing the same.SOLUTION: A rare earth magnet 100 comprises a main phase 10 and a grain boundary phase 20, of which the whole composition is given by the following formula: (NdxLayCezR1w)pFe(100-p-q-r-s-t-u)CoqBrGasCutM1u (R2aR3bM2(1-a-b))v (R1 is one of rare earth elements excluding Nd, La and Ce, R2 is an element selected from Pr, Nd, Pm, Sm, Eu and Gd, R3 is a rare earth element other than R2, M1 is e.g. a predetermined element, and M2 is an alloy element or the like, which lowers a melting point, and 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, where the figures are represented by atom%.)SELECTED DRAWING: Figure 2

Description

The present disclosure relates to an R—Fe—B rare earth magnet (R is a rare earth element) and a method for manufacturing the same. The present disclosure particularly relates to an R—Fe—B rare earth magnet in which a decrease in coercive force at high temperatures is particularly suppressed, and a method for manufacturing the same.

The R-Fe-B rare earth magnet includes a main phase and a grain boundary phase existing 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 develops strong magnetism. On the other hand, the grain boundary phase exists around the main phase and magnetically separates the main phases. Due to this magnetic division, the coercive force of the R-Fe-B rare earth magnet is increased.

Various attempts have been made to enhance this magnetic decoupling effect. For example, Patent Document 1 discloses a rare earth magnet in which a rare earth magnet having a main phase and a grain boundary phase is used as a precursor, and a modifier is impregnated into the precursor.

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

International Publication 2014/196605 A1

Since the R-Fe-B rare earth magnet has high performance, its use is expanding to various fields. Therefore, R-Fe-B rare earth magnets are increasingly used in high temperature environments. In addition, when the R-Fe-B rare earth magnet is used in a high-power motor and the high output is maintained for a long time, the R-Fe-B rare-earth magnet may become high temperature due to self-heating of the motor. is there.

When the temperature of the R-Fe-B rare earth magnet becomes high, the coercive force generally decreases, but there are also applications in which the decrease in coercive force is required to be particularly small even if the temperature rises. From these facts, the present inventors have found a problem that there is a demand for an R-Fe-B rare earth magnet in which a decrease in coercive force at high temperature is particularly suppressed even if the coercive force at room temperature is relatively low. It was In addition, in this specification, a high temperature means a range of 130 to 200° C., particularly 140 to 160° C. Moreover, room temperature means the range of 20-25 degreeC. Then, the R-Fe-B rare earth magnet, the main phase, comprising a grain boundary phase present around the main phase, the main phase, comprises a phase having a composition represented by R 2 _Fe 14 _B It refers to a magnet that exists.

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 and a method for manufacturing the same, in which a decrease in coercive force is particularly suppressed at high temperatures.

The present inventors have conducted intensive studies to achieve the above object, and completed the rare earth magnet and the manufacturing method thereof according to the present disclosure. The rare earth magnet and the manufacturing method thereof according to the present disclosure include the following embodiments.
<1> Main phase,
A grain boundary phase existing around the main phase,
Equipped with
Total composition formula ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u · (R 2 a R ³ _b M ² _(1-ab) ) _v (wherein R ¹ is one or more elements selected from the group consisting of rare earth elements other than Nd, La, and Ce, and R ² is Pr, Nd. , Pm, Sm, Eu, and Gd are one or more elements selected from the group consisting of, R ³ is one or more elements selected from the group consisting of rare earth elements other than R ² , and M ¹ is Al , Au, Ag, Zn, In, and Mn are one or more elements selected from the group consisting of unavoidable impurity elements, and M ² is R ² _a R by alloying with R ² and R ^{3. 3} _b M ² _(1-ab) is one or more alloying elements and unavoidable impurity elements that lower the melting point of R ² than the melting point of R ² ,
p, q, r, s, t, u, and v are 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, and w are molar ratios,
0.20≦x≦0.60,
0.40≦y≦0.70,
0≦z≦0.10,
0≦w≦0.10, and x+y+z+w=1
And, and
a and b are molar ratios,
0.50≦a≦0.80 and 0≦b≦0.10
Is represented by
Rare earth magnets.
<2> where x and y are
0.20≦x≦0.40 and 0.50≦y≦0.70
The rare earth magnet according to item <1>.
<3> An intermediate phase is further provided between the main phase and the grain boundary phase,
V is 0.10≦v≦10.0, and the concentration of R ² is higher in the intermediate phase than in the main phase,
The rare earth magnet according to the item <1> or <2>.
<4> The rare earth magnet according to any one of <1> to <3>, wherein the R ² is Nd.
<5> formula ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u ( provided that, ^{R 1} is, Nd, La, and one or more elements selected from the group consisting of rare earth elements other than Ce, M ¹ is one or more elements selected from the group consisting of Al, Au, Ag, Zn, In, and Mn, And inevitable impurity elements,
p, q, r, s, t, and u are 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, and
x, y, z, and w are molar ratios,
0.20≦x≦0.60,
0.40≦y≦0.70,
0≦z≦0.10,
0≦w≦0.10, and x+y+z+w=1
To prepare a molten metal having a composition represented by
Quenching the melt to obtain a ribbon or powder,
Hot compressing the ribbon or the powder to obtain a molded body, and hot forming the molded body to obtain a plastically deformed body,
including,
Manufacturing method of rare earth magnet.
<6> where x and y are
0.20≦x≦0.40 and 0.50≦y≦0.70
The method according to <5>.
<7> R ² _a R ³ _b M ² _(1-ab) (wherein R ² is one or more elements selected from the group consisting of Pr, Nd, Pm, Sm, Eu, and Gd, R ³ is one or more elements selected from the group consisting of rare earth elements other than R ² , and M ² is alloyed with R ² and R ³ to form R ² _a R ³ _b M ² _{(1- a-b)} is one or more alloying elements and unavoidable impurity elements that lower the melting point of R ² below the melting point of R ² , and a and b are in a molar ratio of 0.50≦a≦0.80 and 0. ≦b≦0. 10) providing a modifier containing an alloy represented by:
Contacting the plastic deformable body and the modifier with each other to obtain a contact body, and heat treating the contact body to allow the melt of the modifier to penetrate into the contact body.
including,
The method according to <5> or <6>.
<8> The method according to <7>, wherein R ² is Nd.

According to the present disclosure, a rare earth magnet and a method for producing the same, in which the crystal stability of the R ₂ Fe ₁₄ B phase is maintained and a relatively large amount of La is contained, thereby particularly suppressing a decrease in coercive force at high temperatures, are provided. can do.

FIG. 1 is a diagram showing an appropriate range of the molar ratio of Nd, La, and Ce. FIG. 2 is a diagram schematically showing one aspect of the structure of the rare earth magnet according to the present disclosure. FIG. 3 is a diagram schematically showing another aspect of the structure of the rare earth magnet according to the present disclosure. FIG. 4 is a schematic diagram for explaining a method for forming a ribbon by the liquid quenching method. FIG. 5: is a schematic diagram explaining the method of compressing powder hot using a punch and a die. FIG. 6 is a schematic diagram for explaining a method of hot plastic working a compact using a punch and a die. FIG. 7 is a diagram showing the compositions of the samples of Examples and Comparative Examples in FIG. FIG. 8 is a diagram showing the results of observation of the structure of the sample of Example 3. FIG. 9 is a diagram showing the result of component analysis of the white line part in FIG.

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

In the R—Fe—B rare earth magnet, when R is Nd and La (hereinafter, such a rare earth magnet may be referred to as “(Nd, La)—Fe—B rare earth magnet”), the main phase. Is a (Nd, La) ₂ Fe ₁₄ B phase. In the (Nd, La) ₂ Fe ₁₄ B phase, Nd makes a large contribution to exhibiting high magnetization and high coercive force at room temperature. However, Nd causes a decrease in coercive force at high temperatures. On the other hand, in the (Nd, La) ₂ Fe ₁₄ B phase, La has a small contribution to exhibiting high magnetization and high coercive force at room temperature. However, La greatly contributes to suppressing the decrease in coercive force at high temperatures.

In the (Nd, La)-Fe-B system rare earth magnet, the coercive force at room temperature does not have to be so high, but if it is desired to suppress the decrease in coercive force as the temperature rises from room temperature, La It is possible to increase the molar ratio. However, among the rare earth elements, La has a particularly large atomic radius, and the crystal stability of the La ₂ Fe ₁₄ B phase is very low, so that it is very difficult for the La ₂ Fe ₁₄ B phase to exist. Also, when a part of La is replaced with Nd to form a (Nd, La) ₂ Fe ₁₄ B phase as a main phase, the crystal stability of the La decreases sharply as the molar ratio of La increases. To do.

However, in the (Nd, La)-Fe-B system rare earth magnet, when the molar ratio of La is set in an appropriate range, the La ₂ Fe ₁₄ B phase secures crystal stability, and a decrease in coercive force at high temperature is particularly caused. The present inventors have found that it can be suppressed. Further, even if a small amount of Ce is added to such a (Nd, La)-Fe-B rare earth magnet, the decrease in coercive force at high temperature is particularly suppressed (Nd, La, Ce)-Fe-. The present inventors have found that a B-based rare earth magnet can be obtained.

Furthermore, the present inventors have found the following. The (Nd, La)-Fe-B rare earth magnet or the (Nd, La, Ce)-Fe-B rare earth magnet is used as a precursor, and a modifying agent containing R ² is added to the inside of the precursor. When infiltrated, an intermediate phase is formed between the main phase and the grain boundary phase depending on the amount of the alloy infiltrated into the modifier. Without being bound by theory, it is believed that this is because some of the Nd, Ce, and/or La present in the main phase of the precursor is replaced with R ² to form the mesophase. Generally, at higher temperatures, the anisotropic magnetic field decreases. However, when the concentration of R ² is higher in the intermediate phase than in the main phase, the anisotropic magnetic field of the intermediate phase becomes higher than the anisotropic magnetic field of the main phase. Therefore, the permeation of the modifier contributes to the improvement of the coercive force at room temperature and the suppression of the decrease of the coercive force at high temperature.

The constituent features of the rare earth magnet and the manufacturing method thereof according to the present disclosure based on these findings will be described below.

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

<Overall composition>
Overall composition of the rare earth magnet of the present disclosure, the formula ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u - represented by ^{_{(R 2 a R 3 b M}} 2 (1-a-b)) v. The rare earth magnet of the present disclosure has a main phase and a grain boundary phase existing around the main phase. The “whole composition” means the composition of the entire rare earth magnet including the main phase and the grain boundary phase.

Rare earth magnet of the present disclosure _is represented by ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u Based on rare earth magnets. Rare earth magnet of the present disclosure, the rare-earth magnet according to this _{^{basic, R 2 a R 3 b M}} 2 (1-a-b) alloys may be optionally impregnated with modifier containing represented by. When the modifier is permeated, the basic 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-a-b)) v represents the composition derived from the modifier. If not impregnated with modifier, v = 0, the overall composition of the rare earth magnet of the present ^{_{disclosure, (Nd x La y Ce z}} R 1 w) p Fe (100-p-q-r-s-t- _u) represented by _{Co q B r Ga s Cu t} M 1 u. On the other hand, when infiltrating a modifier, v is the value of the positive non-zero, the overall composition of the rare earth magnet of the present ^{_{disclosure, (Nd x La y Ce z}} R 1 w) p Fe (100-p-q- represented by _r-s-t-u) Co q B r Ga s Cu t M 1 u · (R 2 a R 3 b M 2 (1-a-b)) v.

In the above formula, Nd is neodymium, La is lanthanum, Ce is cerium, R ¹ is at least one element selected from the group consisting of Nd, La, and rare earth elements other than Ce, Fe is iron, Co is cobalt, B Is boron, Ga is gallium, and Cu is copper. M ¹ is at least one element selected from the group consisting of Al, Au, Ag, Zn, In, and Mn, and an unavoidable impurity element. Al is aluminum, Au is gold, Ag is silver, Zn is zinc, In is indium, and Mn is manganese. R ² is one or more elements selected from the group consisting of Pr, Nd, Pm, Sm, Eu, and Gd. Pr is praseodymium, Nd is neodymium, Pm is promethium, Sm is samarium, Eu is eurobium, and Gd is gadolinium. R ³ is one or more elements selected from the group consisting of rare earth elements other than R ² . M ² is by ^{R 2} and ^{R 3 _{alloyed, R 2 a R 3 b M}} 2 (1-a-b) a melting point of, one or more alloying elements and inevitable lowering than the melting point of the ^{R 2} Is an impurity element.

In the present specification, the rare earth elements are 17 elements of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Of these, Sc, Y, La, and Ce are light rare earth elements. Pr, Nd, Pm, Sm, Eu, and Gd are medium rare earth elements. Tb, Dy, Ho, Er, Tm, Yb, and Lu are heavy rare earth elements. In general, the rarity of heavy rare earth elements is high and the rarity of light rare earth elements is low. The rarity of medium rare earth elements is between heavy rare earth elements and light rare earth elements.

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

p, q, r, s, t, and u represent the following contents of the rare earth magnet, respectively. p is the total content of Nd, Ce, La, and R ¹ , q is the content of Co, r is the content of B, s is the content of Ga, and t is the content of Cu. And u is the content of M ¹ . Further, v indicates the amount of the alloy infiltrated into the modifier with respect to 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 shows the molar ratio of Nd with respect to the total content of Nd, La, Ce, and R ¹ . y represents the molar ratio of La to the total content of Nd, La, Ce, and R ¹ . z represents the molar ratio of Ce to the total content of Nd, La, Ce, and R ¹ . w represents Nd, La, Ce, and to the total content of ^{R 1,} the molar ratio of ^{R 1.} The sum of x, y, z, and w is 1, that is, x+y+z+w=1. The values of a and b are the following molar ratios (content ratios) of the modifier. a ^is to the total content of R 2, ^{R 3,} and ^{M 2,} a molar ratio of ^{R 2.} b ^is to the total content of R 2, ^{R 3,} and ^{M 2,} a molar ratio of ^{R 3.}

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

<Nd>
Nd is an essential component in the rare earth magnet of the present disclosure. Nd forms a (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B phase together with La, Ce, and R ¹ . In the (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B phase, Nd contributes to exhibiting high magnetization and high coercive force at room temperature. However, Nd causes a decrease in coercive force at high temperatures. Therefore, La described below is added.

<La>
La is an essential component in the rare earth magnet of the present disclosure. In the (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B phase, La contributes to suppressing the decrease in coercive force at high temperatures. However, when the molar ratio of La becomes high, the crystal stability of the (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B phase significantly decreases, so the molar ratio of La is set within a predetermined range. The molar ratio of La will be described later.

<Ce>
Ce is an optional component of the rare earth magnets of the present disclosure. A small amount of Ce in the (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B phase contributes to the suppression of the decrease in coercive force at high temperatures. The molar ratio of Ce will be described later.

<R ¹ >
R ¹ is one or more elements selected from the group consisting of rare earth elements other than Nd, La, and Ce. The rare earth magnet of the present disclosure contains Nd and La as essential components and Ce as an arbitrary component. In rare earth magnets, it is difficult to eliminate rare earth elements other than Nd, La, and Ce due to raw materials and the like. Therefore, Nd, La, and the rare earth elements other than Ce as ^{R 1,} and define the acceptable molar ratios. The allowable molar ratio will be described later.

<Molar ratio of Nd, La, Ce, and R ¹ >
The molar ratios of Nd, La, Ce, and R ¹ are represented by x, y, z, and w, respectively. The sum of x, y, z, and w is 1.

The rare earth magnet according to the present disclosure essentially contains Nd and La as rare earth elements, and optionally contains a small amount of Ce. Further, the rare earth magnets of the present disclosure may contain traces of R ¹ . Ce is an element that may be intentionally contained, and R ¹ is an element that is allowed to be contained within a range that does not substantially adversely affect the magnetic characteristics of the rare earth magnet of the present disclosure. If the value of the molar ratio w of R ¹ is in the range of 0 to 0.10. It may be considered that the characteristics of the rare earth magnet of the present disclosure are substantially equivalent to those when the value of w is 0. .. The value of w is preferably as small as possible, and may be 0.08 or less, 0.06 or less, 0.04 or less, 0.02 or less.

R ¹ is a small amount, and it is considered that there is substantially no influence on the magnetic characteristics of the rare earth magnet of the present disclosure. Therefore, regarding the respective molar ratios of Nd, La, and Ce, there is practically no problem considering the ternary system of Nd, La, and Ce. Therefore, the appropriate ranges of the molar ratio x of Nd, the molar ratio y of La, and the molar ratio z of Ce will be described with reference to the ternary composition region diagram of Nd, La, and Ce.

FIG. 1 is a ternary composition region diagram of Nd, La, and Ce, and is a diagram showing an appropriate range of the molar ratio of Nd, La, and Ce. In FIG. 1, the composition of a region surrounded by a straight line AB, a straight line BC, a straight line CD, and a straight line DA (a hatched region, hereinafter, may be referred to as “ABCD region”) has a coercive force at high temperature. Can be particularly suppressed.

In the ABCD region, the molar ratio x of Nd is 0.20≦x≦0.60, the molar ratio y of La is 0.40≦y≦0.70, and the molar ratio z of Ce is 0≦. It is a region where z≦0.10. In the ABCD region, when the molar ratio y of La is higher than that of the straight line AB (when the molar ratio x of Nd is low), the action of La can be fully enjoyed, and the decrease in coercive force at high temperature can be particularly suppressed. In the ABCD region, if the molar ratio y of La is lower than that of the linear CD (the molar ratio x of Nd is higher), the crystallinity of the (Nd, La, Ce) ₂ Fe ₁₄ B phase will not be significantly reduced. Further, the α-Fe phase is rarely formed in place of the (Nd, La, Ce) ₂ Fe ₁₄ B phase. In the ABCD region, if the molar ratio z of Ce is lower than that of the straight line BC, a large amount of CeFe ₂ phase or the like is formed in the grain boundary phase, and the coercive force is less likely to decrease at high temperature.

The outer edge of the ABCD region may be reduced. Specifically, the lower limit value of x may be 0.25, 0.30, or 0.35. The upper limit for x may be 0.55, 0.50, 0.45, or 0.40. The lower limit value of y may be 0.45 or 0.50. The upper limit value of y may be 0.65, 0.60, or 0.55. The lower limit for z may be 0.01, 0.02, 0.03, or 0.04. The upper limit for z may be 0.09, 0.08, 0.07, 0.06, or 0.05.

<Total content of Nd, La, Ce, and R ¹ >
When the total content p of Nd, La, Ce, and R ¹ is 5.0 atom% or more, the main phase is easily formed. From the viewpoint that the main phase is easily formed, p may be 7.0 atom% or more, 9.0 atom% or more, 11.0 atom% or more, or 13.0 atom% or more. On the other hand, if p is 20.0 atomic% or less, the existence ratio (volume ratio) of the grain boundary phase will not be excessive. From the viewpoint that the existence ratio of the grain boundary phase does not become excessive, it may be 19.0 atom% or less, 18.0 atom% or less, or 17.0 atom% 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. When the content of B is too small, the main phase is hard to be generated. When the content r of B is 4.0 atomic% or more, the main phase is not easily generated. From this viewpoint, r may be 4.5 atom% or more, 5.0 atom% or more, or 5.5 atom% or more. On the other hand, when the content r of B is excessive, the magnetic phase containing Fe such as RFe ₄ B ₄ phase and the α-Fe phase are easily generated in the grain boundary phase. When r is 6.5 atomic% or less, it is difficult to produce a large amount of Fe-containing magnetic phase and α-Fe phase. From this viewpoint, r may be 6.3 atomic% or less, or 6.0 atomic% or less.

<Co>
Co is an element that can replace Fe in the main phase, the grain boundary phase, and the intermediate phase. In the present specification, when it is described as Fe, a part of Fe can be replaced with Co. For example, a 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. The magnetic phase containing Fe in the grain boundary phase (R ₂ Fe ₁₇ phase or the like) becomes a magnetic phase (R ₂ (Fe, Co) ₁₇ phase or the like) in which a part of Fe is replaced by Co.

Thus, by substituting a part of Fe with Co, the Curie point of each phase is improved. When it is not desired to improve the Curie point, Co may not be contained and 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 atom% or more, 2.0 atom% or more, 3.0 atom% or more, or 4.0 atom% or more. On the other hand, since Co is expensive, the content q of Co may be 8.0 atom% or less, 7.0 atom% or less, or 6.0 atom% or less from the economical viewpoint.

<Ga>
Ga is an element that lowers the melting point of the grain boundary phase, and may be optionally contained in the rare earth magnet of the present disclosure. When a ribbon or the like is obtained by a liquid quenching method or the like, and a molded body is obtained from the ribbon or the like, and/or when a plastically deformed body is obtained from the molded body, the inclusion of Ga lowers the melting point of the grain boundary phase. Further, since the lubricity is increased, it contributes to the improvement of the mold life and the like. From this viewpoint, 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 atomic% or less. It may be up to 4 atom %. The molded body and the plastically deformable body will be described later.

<Cu>
Cu is an element that lowers the melting point of the grain boundary phase, and may be optionally contained in the rare earth magnet of the present disclosure. When a ribbon or the like is obtained by a liquid quenching method or the like, and a molded body is obtained from the ribbon or the like, and/or when a plastically deformed body is obtained from the molded body, the melting point of the grain boundary phase is lowered by the inclusion of Cu. Further, since the lubricity increases, it contributes to the improvement of the life of the mold. From this viewpoint, 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 It may be up to 4 atom %. The molded body and the plastically deformable body will be described later.

<M ¹ >
M ¹ is an element that can be contained within a range that does not impair the characteristics of the rare earth magnet of the present disclosure. M ¹ may contain an unavoidable impurity element. The unavoidable impurity element is an impurity element contained in the raw material of the rare earth magnet, an impurity element mixed in the manufacturing process, or the like. An impurity element that causes an increase in cost. 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 characteristics due to manufacturing reasons.

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

Al, Au, Ag, Zn, and In lower the melting point of the grain boundary phase existing inside the ribbon or the like obtained by the liquid quenching method or the like. Thereby, when a molded product is obtained from a thin strip and/or when a plastically deformed product is obtained from the molded product, it acts as a lubricant and is advantageous in improving the life of the mold, but the content of these elements is Not required. Then, if the content of M ¹ is not more than the upper limit, these elements do not substantially affect the magnetic characteristics of the rare earth magnet of the present disclosure. From the viewpoint of magnetic properties, these elements may be regarded as unavoidable impurity elements. The molded body and the plastically deformable body will be described later.

Mn _is, (Nd, Ce, La) by replacing a portion of the 2 _{Fe 14} Fe in the B _phase, (Nd, Ce, La) contributes to the stabilization of 2 _{Fe 14} B phase.

When the content u of M ¹ is 2.0 atomic% or less, the magnetic characteristics of the present disclosure are not impaired. From this viewpoint, the content u of M ¹ may be 1.5 atomic% or less, 1.0 atomic% or less, or 0.5 atomic %.

As ^{M 1, Al, Au, Ag} , Zn, In, and even when containing no Mn, because it is not possible to completely eliminate the unavoidable impurity elements, the lower limit of the content u of ^{M 1} is 0.05 atomic% , 0.1 atom %, or 0.2 atom %, there is no practical problem.

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

The values of p, q, r, s, t, and u, which have been described so far, are the same as in the case of a normal R-Fe-B-based rare earth magnet.

<Fe>
Fe is the balance of Nd, La, Ce, R ¹ , Co, B, Ga, Cu, and M ¹ described so far, and the Fe content (atomic %) is (100-pqqr -S-t-u). When p, q, r, s, t, and u are in the ranges described above, the main phase and the grain boundary phase are obtained. Further, when a rare earth magnet having a main phase and a grain boundary phase is used as a precursor and the modifier is sufficiently penetrated into the precursor, an intermediate phase is obtained. Details of the main phase, grain boundary phase, and intermediate phase will be described later.

<R ² , R ³ , and M ² >
Expression for the overall composition of the rare earth magnet of the present disclosure _{^{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u · in _{^{(R 2 a R 3 b M}} 2 (1-a-b)) v, (R 2 a R 3 b M 2 (1-a-b)) v represents the composition derived from the modifier. _{^{Further, R 2 a R 3 b M}} 2 (1-a-b) represents the composition of the alloy in the modifier. Further, v represents the permeation amount (atomic %) of the modifier into the rare earth magnet (rare earth magnet precursor) before the modifier is permeated.

R ² is one or more elements selected from the group consisting of Pr, Nd, Pm, Sm, Eu, and Gd. R ³ is one or more elements selected from the group consisting of rare earth elements other than R ² . Then, ^{M 2} is by ^{R 2} and ^{R 3 _{alloyed, R 2 a R 3 b M}} 2 (1-a-b) a melting point of one or more alloying elements to lower than the melting point of the ^{R 2} And an unavoidable impurity element. The unavoidable impurity element refers to an impurity element such as an impurity element contained in a raw material, which is unavoidable to avoid, or causes a significant increase in manufacturing cost to avoid it.

For R ² and ^{M 2,} from the viewpoint of easily forming these eutectic alloys, Nd is preferred as ^{R 2,} as the ^{M 2} Cu, Al, and an element on one selected from the group consisting of Co Is preferred, and Cu is particularly preferred as M ² . In addition, Cu, Al, and Co have a small adverse effect on the magnetic characteristics and the like of the rare earth magnet.

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 R ² . The melting point of the alloy in the modifier depends on the R ² molar ratio a of the alloy in the modifier. The melting point of the alloy in the modifier, to reduce the melting point of ^{R 2,} the molar ratio a for ^{R 2,} 0.50 or more, may be 0.55 or more, or 0.60 or more, 0 It may be 0.80 or less, 0.75 or less, or 0.70 or less. The molar ratio a is the total of the molar ratios of R ² when two or more kinds of elements are included.

The main rare earth element contained in the alloy in the modifier is R ² , but it is difficult to eliminate the rare earth element R ³ other than R ² . However, when the value of the molar ratio b of R ³ is 0 to 0. 10, it can be considered that the property as the modifier is substantially equal to that 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 as low as possible, 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 arbitrarily penetrating the basic rare earth magnet (rare earth magnet precursor) with the modifier. On the other hand, if the amount of permeation of the modifying material is excessive, the magnetization decreases due to M ² in the modifying material. Therefore, the permeation amount of the modifier may be appropriately determined by the balance between improvement of coercive force and decrease of magnetization. The penetration amount v of the modifier into the rare earth magnet (rare earth magnet precursor) before the modifier is permeated is 0 atom% or more, 1.0 atom% or more, 3.0 atom% or more, or 5.0 atom. % Or more, 10.0 atomic% or less, 8.0 atomic% or less, or 6.0 atomic% or less. Note that v of 0 atomic% means that the modifier does not penetrate. Regarding the penetration of the modifier, Patent Document 1 can be referred to.

<Main phase, grain boundary phase, and intermediate phase>
The structure of the rare earth magnet of the present disclosure will be described with reference to the drawings. FIG. 2 is a diagram schematically showing one aspect of the structure of the rare earth magnet according to the present disclosure. FIG. 3 is a diagram schematically showing another aspect of the structure of the rare earth magnet according to the present disclosure.

In the embodiment shown in FIG. 2, the rare earth magnet 100 of the present disclosure has the main phase 10 and the grain boundary phase 20. In the embodiment shown in FIG. 3, the rare earth magnet 100 of the present disclosure further has an intermediate phase 30 in addition to the main phase 10 and the grain boundary phase 20.

The embodiment shown in FIG. 2 is observed when the modifier is not impregnated or when a very small amount of modifier is impregnated. The rare earth magnet 100 of the embodiment shown in FIG. 2 is used as a rare earth magnet precursor into which a modifier is permeated. The embodiment shown in FIG. 3 is observed when the rare earth magnet precursor is infiltrated with a sufficient amount of the modifier.

The main phase 10 is a (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B phase. The (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B phase means a phase having a (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B type crystal structure. The (Nd, La, Ce, R ¹ ) ₂ Fe ₁₄ B type crystal structure means that a small amount of an element other than Nd, La, Ce, R ¹ , Fe and B may be contained in the crystal. To do. Such elements are typically Ga, Cu, M ¹ and unavoidable impurity elements. The grain boundary phase 20 is a (Nd, La, Ce, R ¹ ) rich phase. ^{(Nd, La, Ce, R} 1) rich phase, than the main phase 10, (Nd, La, Ce, main phase 10 by a phase containing a large amount of ^{R 1.} Grain boundary phase 20 are magnetically separated Therefore, the coercive force is improved.

The rare earth magnet 100 may contain a phase (not shown) other than the main phase 10, the grain boundary phase 20, and the intermediate phase 30. Examples of phases other than the main phase 10, the grain boundary phase 20, and the intermediate phase 30 include oxides, nitrides, and intermetallic compounds.

The characteristics of the rare earth magnet 100 are mainly exerted by the main phase 10, the grain boundary phase 20, and the intermediate phase 30. Most of the phases other than the main phase 10, the grain boundary phase 20, and the intermediate phase 30 are impurities. Therefore, the total content of the main phase 10, the grain boundary phase 20, and the intermediate phase 30 with respect to the rare earth magnet 100 is preferably 95% by volume or more, more preferably 97% by volume or more, and even more preferably 99% by volume or more. ..

The main phase 10 is nanocrystallized. Nanocrystallized means that the main phase 10 has an average particle size of 1 to 1000 nm. The average particle size 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.

The “average particle size” is, for example, the average value of the length t of the main phase 10 in the longitudinal direction shown in FIG. For example, in a scanning electron microscope image or a transmission electron microscope image of the rare earth magnet 100, a fixed region is defined, and an average value of the lengths t of the main phases 10 existing in this fixed region is calculated, The average particle size". When the cross-sectional shape of the main phase 10 is elliptical, the length of its major axis is t. When the cross section of the main phase is quadrangular, the length of the longer diagonal line is t. In the case of the embodiment shown in FIG. 3, t is set including the intermediate phase 30. This is because the intermediate phase 30 is derived from the main phase 10, as described later.

When the rare earth magnet 100 shown in FIG. 2 is used as a rare earth magnet precursor and the modifier is infiltrated therein, the modifier reaches the interface between the main phase 10 and the grain boundary phase 20 through the grain boundary phase 20. .. Then, R ² in the modifier penetrates from the grain boundary phase 20 into the inside of the main phase 10, and a part of La and/or Ce in the main phase 10 is discharged to the grain boundary phase 20. As shown, the interphase 30 is formed.

The grain boundary phase 20 exists around the main phase 10. The intermediate phase 30 is sandwiched between the main phase 10 and the grain boundary phase 20. The formation of the intermediate phase 30 will be described in terms of the composition of the modifier.

The rare earth magnet 100 used as a rare earth magnet precursor (hereinafter, may be referred to as “rare earth magnet precursor”) mainly contains Nd, La, and Ce as rare earth elements. On the other hand, the alloy in the modifier mainly contains R ² which is one or more elements selected from the group consisting of Pr, Nd, Pm, Sm, Eu and Gd as a rare earth element.

The modifier R ² and the rare earth magnet precursors Nd, La, and Ce differ in one or more kinds of rare earth elements. Therefore, without being bound by theory, R ² penetrates into the main phase 10 and forms the intermediate phase 30. Therefore, the concentration of R ² is higher in the intermediate phase 30 than in the main phase 10. Without being bound by theory, it is believed that the reason for the penetration of R ^{2 into} the main phase 10 is as follows.

When the rare earth magnet precursor is infiltrated with the improving material, when the alloy in the modifying material mainly contains the same rare earth element as the main phase 10, the rare earth element in the modifying material is difficult to penetrate into the main phase 10. .. For example, when the Nd-Fe-B rare earth magnet precursor is infiltrated with the modifier containing the Nd-Cu alloy, Nd in the modifier is likely to remain in the grain boundary phase 20 and penetrate into the main phase 10. It's hard to do.

On the other hand, when the alloy in the modifier mainly contains a rare earth element different from the main phase 10, the rare earth element in the modifier is likely to penetrate into the main phase 10. For example, when a modifier containing an Nd-Cu alloy is infiltrated into a (Nd, La, Ce)-Fe-B rare earth magnet precursor, the presence of La and Ce causes the Nd in the modifier to change, It easily penetrates into the main phase 10. This is because La and Ce in the (Nd, La, Ce)-Fe-B based rare earth magnet precursor are replaced with Nd in the Nd-Cu alloy. Thereby, the concentration of R ² is higher in the intermediate phase 30 than in the main phase 10, and the concentrations of La and Ce are higher in the main phase 10 than in the intermediate phase 30. From the viewpoint of improving the saturation magnetization and the anisotropic magnetic field of the intermediate phase 30 in a well-balanced manner, R ² is preferably Nd.

The composition of the alloy in the modifier ^is represented by _{^{R 2 a R 3 b M 2}} (1-a-b). R ³ is one or more selected from rare earth elements other than R ² . The rare earth element contained in the alloy in the modifier is R ² , but it is difficult to eliminate the rare earth element R ³ other than R ² . However, when the value of the content ratio b of R ³ is 0 to 0.1, the property as the modifier may be considered to be substantially equivalent to that 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 as low as possible, as long as it does not increase the manufacturing cost, and may be 0.09 or less, 0.08 or less, 0.07 or less, or 0.06 or less. The value of a will be described later.

Wherein the entire composition ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u · (R 2 a R 3 _{In b} M ² _(1-a-b) ) _v , the value of v corresponds to the amount of penetration (atomic %) of the alloy in the improved material with respect to the precursor 100. Depending on the value of v, the concentration of R ² in the intermediate phase 30 and the thickness of the intermediate phase 30 change.

In FIG. 3, when the R ² concentration is 1.1 times or more higher in the intermediate phase 30 than in the main phase 10, the magnetic fragmentation can be more clearly recognized. On the other hand, even if the concentration of R ² is 2.0 times or more higher in the intermediate phase 30 than in the main phase 10, the effect of magnetic decoupling is not saturated. Therefore, the concentration of R ² is preferably 1.1 to 2.0 times higher in the intermediate phase 30 than in the main phase 10. The concentration of R ² may be 1.1 to 1.8 times higher or 1.1 to 1.5 times higher.

In order to more clearly recognize the function of the intermediate phase 30, the thickness of the intermediate phase 30 is preferably 2 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more. On the other hand, the thickness of the intermediate phase 30 depends on the permeation amount of the modifier. Since the modifier contains M ² that does not contribute to the magnetization, if the permeation amount is too large, the volume fraction of the grain boundary phase increases and the magnetization of the rare earth magnet 100 decreases. From this viewpoint, the thickness of the intermediate phase 30 is preferably 100 nm or less, more preferably 70 nm or less, and even more preferably 40 nm or less.

The rare earth magnet of the present disclosure is suitable for applications in which a decrease in coercive force at high temperatures is particularly suppressed even when the coercive force at room temperature is relatively low. Examples of such applications include auxiliary motors for automobiles, motors for driving electric motorcycles, and motors for driving electric bicycles. Since such a motor has a small maximum rated capacity, it may have a relatively small coercive force at room temperature. However, when the load is high, it is often used in the vicinity of the rated maximum capacity, so that it easily self-heats. Moreover, since it is often used in a narrow space, it is often difficult to provide a cooling means. Therefore, it is particularly important that the coercive force does not easily decrease even at high temperatures. Examples of auxiliary motors for automobiles include motors for electric power steering (Electric Power Steering).

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

<Preparation of molten metal>
Preparing a melt of the formula ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u. Regarding Nd, La, Ce, R ¹ , Fe, Co, B, Ga, Cu, and M ¹ , and regarding x, y, z, w, p, q, r, s, t, and u. The same applies to the description of rare earth magnets. In addition, when a specific component is depleted during the preparation of the molten metal or in the subsequent step, the amount may be estimated.

There is no limitation on the method for preparing the molten metal, and examples thereof include high-frequency melting of the raw materials. The preparation of the molten metal is preferably carried out in an inert gas atmosphere in order to prevent oxidation of the raw material during melting and the molten metal during holding. The inert gas atmosphere includes a nitrogen gas atmosphere.

<Formation of ribbon or powder>
The above melt is rapidly cooled to obtain a ribbon or powder. The quenching method is not particularly limited as long as the main phase in the ribbon or powder can be nanocrystallized. For example, a liquid quenching method can be mentioned.

The liquid quenching method will be briefly described. FIG. 4 is a schematic diagram illustrating a method for forming a ribbon by the liquid quenching method. For example, in an oven at an Ar gas atmosphere under reduced pressure below 50 kPa (not ^{_{shown), (Nd x La y Ce}} z R 1 w) p Fe (100-p-q-r-s-t-u) Co q B obtain a molten high-frequency heating the alloy having a composition expressed in _{^{r Ga s Cu t M 1 u}} . This molten metal is discharged from the nozzle 60 to the cooling roll 62 to obtain the thin strip 64. Although FIG. 4 shows a mode of obtaining the thin strip 64, 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 ribbon or powder. The cooling rate of the melt may typically be 1×10 ² K/sec or more, 1×10 ³ K/sec or more, or 1×10 ⁴ K/sec or more, 1×10 ⁷ K/sec. Hereafter, it may be 1×10 ⁶ K/sec or less, or 1×10 ⁵ K/sec or less.

The molten metal discharge temperature is typically 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 may be 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. You can

<Formation of molded body>
A ribbon or powder obtained by liquid quenching is hot-compressed to obtain a molded body. Before hot pressing the ribbon, the ribbon may be ground to 10 μm or less.

The temperature at which the ribbon or powder is hot-compressed may be appropriately set to a temperature at which the nanocrystal grains do not become coarse and a molded body is obtained. The temperature at which the ribbon or powder is hot compressed may be a temperature at which a part of the grain boundary phase in the ribbon or powder melts. That is, the ribbon or powder may be liquid-phase sintered. The atmosphere when hot compressing the ribbon or powder is preferably an inert gas atmosphere in order to prevent the ribbon or powder and the molded body from being oxidized. The inert gas atmosphere includes a nitrogen gas atmosphere. Alternatively, the powder obtained by crushing the thin strip may be compacted to obtain a compact, and then the compact may be sintered (including liquid phase sintering).

The heating temperature when hot pressing the ribbon or powder may be typically 550°C or higher, 570°C or higher, 600°C or higher, or 630°C or higher, and 750°C or lower, 720°C or lower. , 700°C or lower, or 670°C or lower.

The pressure when hot pressing the ribbon or powder may be appropriately determined so that a molded product having a desired density can be obtained. By applying pressure, a molded product can be obtained without raising the temperature during molding excessively. Therefore, the nanocrystals do not become coarse. The pressure when hot compressing the ribbon or powder may be typically 200 MPa or higher, 300 MPa or higher, or 350 MPa or higher, and may be 600 MPa or lower, 500 MPa or lower, or 450 MPa or lower.

The pressing time for hot pressing the ribbon or powder may be typically 1 second or longer, 5 seconds or longer, 20 seconds or longer, or 40 seconds or longer, and 120 seconds or shorter, 100 seconds. Or less, or 80 seconds or less.

The method for hot-pressing the magnetic ribbon or magnetic powder is not particularly limited, and examples thereof include a method using a die and a punch.

A method of using a die and a punch will be briefly described. FIG. 5: is a schematic diagram explaining the method of compressing powder hot using a punch and a die. First, the die 70 and the punch 72 are prepared. The punch 72 slides in the cavity of the die 70. The powder 74 is charged into the cavity surrounded by the die 70 and the punch 72, and is pressed by the punch 72 in the direction of the arrow in FIG. The die 70 is heated before and/or after the powder 74 is charged. The die 70 may be heated during pressurization. Although the powder 74 is hot-compressed in FIG. 5, the ribbon 64 may be hot-compressed.

<Formation of plastic deformation body>
After the ribbon or powder is hot compressed to obtain a molded body, the molded body is further subjected to hot plastic working to obtain a plastically deformed body. Thereby, anisotropy can be given to the rare earth magnet of this indication.

The rolling reduction during hot plastic working may be appropriately set so as to obtain desired anisotropy. The reduction ratio during hot plastic working may be 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 the nanocrystals are not coarsened. The temperature during the 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 prevent the nanocrystals in the compact from coarsening during the hot plastic working, the strain rate during the hot plastic working is preferably high. On the other hand, if the strain rate during the hot plastic working is excessively high, the wear of the die and punch used for the hot plastic working becomes remarkable. 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. It may be s or more, 10.0/s or less, 5.0/s or less, 3.0/s or less, or 2.0/s or less.

The method of hot plastic working of the molded body is not particularly limited, but examples thereof include upsetting and backward extrusion. Here, a method of using a die and a punch will be briefly described as an example of a method of hot plastic working a compact.

FIG. 6 is a schematic diagram for explaining a method of hot plastic working a compact using a punch and a die. First, the die 70 and the punch 72 are prepared. The punch 72 slides in the cavity of the die 70. The punch 72 is brought into contact with the end surface 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 molded body 76. The die 70 may be heated during pressurization.

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

<Preparation of modifier>
A modifier containing an alloy having a composition represented by the formula R ² _a R ³ _b M ² _(1-a-b) is prepared. The matters concerning R ² , R ³ , and M ² , and the matters concerning a and b are the same as those of the rare earth magnet.

In the alloy having the composition represented by R ² _a R ³ _b M ² _(1-a-b) , M ² is alloyed with R ² and R ^3, and thus R ² _z R ³ _w M ² _(1- The melting point of _ab) is lower than the melting point of R ² . Thereby, the alloy in the modifier can be melted without raising the temperature of the heat treatment described below excessively. As a result, the alloy in the modifier can penetrate into the plastic deformable body without coarsening the nanocrystals in the plastic deformable body.

_Examples of the alloy having the composition represented by R ² _z R ³ _w M ² _(1-a-b) include Nd-Cu alloy, Pr-Cu alloy, Nd-Pr-Cu alloy, Nd-Al alloy, and Pr-Al. Examples thereof include alloys, Nd-Pr-Al alloys, Nd-Co alloys, Pr-Co alloys, and Nd-Pr-Co alloys.

The method for producing the modifier is not particularly limited. Examples of the method of manufacturing the modifier 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 the variation in alloy components depending on the site of the modifier.

The permeation amount of the alloy in the modifier is represented by v (atomic %) in the formula of the overall composition. The matters regarding v are the same as those for the rare earth magnet.

<Formation of contact body>
The plastic deformable body and the modifier are brought into contact with each other to obtain a contact body. At this time, at least one surface of the plastically deformable body and at least one surface of the modifier are brought into contact with each other. As a result, the melt of the modifier penetrates from the contact surface between the plastic deformable body and the modifier during the heat treatment described later.

<Heat treatment>
The above-mentioned contact body is heat-treated to allow the modifier melt to penetrate into the plastically deformable body to obtain the rare earth magnet of the present disclosure. The penetration of the modifier improves the magnetization and coercive force of the rare earth magnet of the present disclosure, especially the coercive force. This is because the penetration 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 is allowed to penetrate into the plastically deformable body and the coarsening of the nanocrystals in the plastically deformable body is suppressed. The higher the heat treatment temperature, the easier it is for the melt of the modifier to penetrate into the plastic deformable body. From this viewpoint, 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 the coarsening of the nanocrystals in the plastically deformable body. From this viewpoint, 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 the oxidation of the molded body, the plastically deformed body, and the modifier. The inert gas atmosphere includes a nitrogen gas atmosphere.

Hereinafter, the rare earth magnet and the method for manufacturing the same according to the present disclosure will be described in more detail with reference to Examples and Comparative Examples. The rare earth magnet and the method for manufacturing the same according to the present disclosure are not limited to the conditions used in the following examples.

<Preparation of sample>
A melt having a composition of R _13.11 Fe _80.43 B _5.99 Ga _0.37 Cu _0.10 was liquid-cooled to obtain a ribbon. Regarding the rare earth elements, the molar ratios of Nd, La, and Ce are as shown in Table 1. The molar ratios of Nd, La, and Ce for each sample of the example and the comparative example are shown in FIG. In each sample, the contents of Co, M ¹ and R ¹ (rare earth elements other than Nd, La and Ce) were below the measurement limit.

As conditions for liquid quenching, the melt temperature (discharge temperature) was 1450° C., and the roll peripheral speed was 30 m/s. At this time, the cold infusion rate of the hot water was 10 ⁶ K/sec. The liquid quench was performed under a reduced pressure atmosphere of argon gas. It was confirmed by transmission electron microscope (TEM) observation that the ribbon was nanocrystallized.

The thin strip was loaded into a die and hot pressed to obtain a molded body. As the hot compression conditions, the applied pressure was 400 MPa, the heating temperature was 650° C., and the holding time for pressurization and heating was 300 seconds.

The molded body was subjected to hot upsetting (hot plastic working) to obtain a plastically deformed body. In the hot upsetting, a sample having a height of 15 mm was compressed to 4.5 mm. As hot upsetting conditions, the processing temperature was 780° C., the strain rate was 0.01/s, and the rolling reduction was 70%. It was confirmed by a scanning electron microscope (SEM) that the plastically deformed body had oriented nanocrystals.

An Nd _0.7 Cu _0.3 alloy was prepared as a modifier. Nd powder and Cu powder manufactured by Kojundo Chemical Co., Ltd. were weighed, arc-melted, and liquid-cooled to obtain a ribbon. The content of R ³ (rare earth elements other than R ² in the modifier was less than or equal to the measurement limit.

The plastic deformable body and the modifier were brought into contact with each other to obtain a contact body, and the contact body was heat-treated in a heating furnace. The permeation amount of the modifier is as shown in Table 1. The permeation amount of 0 atom% means that the modifier is not permeated. As the heat treatment conditions, the heat treatment temperature was 625° C. and the heat treatment time was 165 minutes.

<Evaluation method>
The coercive force and remanent magnetization of each sample were measured. For the measurement, a pulse excitation type magnetic characteristic measuring device (maximum applied magnetic field: 15T) manufactured by Toei Industry Co., Ltd. was used. Both the coercive force and the residual magnetization were measured at 23°C, 100°C, 140°C and 160°C.

The structure of the sample of Example 3 was observed using a scanning transmission electron microscope (STEM), and component analysis (EDX-ray analysis) was performed.

<Evaluation results>
The evaluation results are shown in Table 2. For coercive force, the gradient ΔHc between 23 and 160° C., and for residual magnetization, the gradient ΔBr between 23 and 160° C. are also shown. FIG. 8 is a diagram showing the results of observation of the structure of the sample of Example 3. FIG. 9 is a diagram showing the result of component analysis of the white line part in FIG.

From Tables 1 and 2 and FIG. 7, the samples of Examples 1 to 7 in which the molar ratio x of Nd, the molar ratio y of La, and the molar ratio z of Ce were within the predetermined ranges were particularly high in absolute value of ΔHc. It can be understood that the size is small and the decrease in coercive force can be suppressed particularly at high temperature. Note that the sample of Comparative Example 7 has a relatively small absolute value of ΔHc, but when the samples that did not permeate the modifying material are compared with each other, the samples of Examples 2 and 4 have smaller absolute values of ΔHc. I understand.

Further, it can be understood from FIG. 8 that the concentration of Nd(R ² ) in the sample of Example 3 is higher in the intermediate phase than in the main phase. This has been confirmed for the samples other than Example 3 in which the modifier is permeated.

Then, in the samples of Comparative Examples 9 and 10, it was confirmed that the (Nd, La) ₂ Fe ₁₄ B phase was not formed and the expression of magnetization was hardly observed.

From the above results, the effects of the rare earth magnet and the manufacturing method thereof according to the present disclosure were confirmed.

10 Main Phase 20 Grain Boundary Phase 30 Intermediate Phase 60 Nozzle 62 Cooling Roll 64 Thin Strip 70 Die 72 Punch 74 Powder 76 Molded Body 78 Plastic Deformable Body 100 Rare Earth Magnet

Claims (8)

With the main phase,
A grain boundary phase existing around the main phase,
Equipped with
Total composition formula ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u · (R 2 a R ³ _b M ² _(1-ab) ) _v (wherein R ¹ is one or more elements selected from the group consisting of rare earth elements other than Nd, La, and Ce, and R ² is Pr, Nd , Pm, Sm, Eu, and Gd are one or more elements selected from the group consisting of, R ³ is one or more elements selected from the group consisting of rare earth elements other than R ² , and M ¹ is Al , Au, Ag, Zn, In, and Mn, and one or more elements selected from the group consisting of inevitable impurities, and M ² is R ² _a R by alloying with R ² and R ^{3. 3} _b M ² _(1-ab) is one or more alloying elements and unavoidable impurity elements that lower the melting point of R ² than the melting point of R ² ,
p, q, r, s, t, u, and v are 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, and w are molar ratios,
0.20≦x≦0.60,
0.40≦y≦0.70,
0≦z≦0.10,
0≦w≦0.10, and x+y+z+w=1
And, and
a and b are molar ratios,
0.50≦a≦0.80 and 0≦b≦0.10
Is represented by
Rare earth magnets. Where x and y are
0.20≦x≦0.40 and 0.50≦y≦0.70
The rare earth magnet according to claim 1, wherein Between the main phase and the grain boundary phase, further, an intermediate phase,
V is 0.10≦v≦10.0, and the concentration of R ² is higher in the intermediate phase than in the main phase,
The rare earth magnet according to claim 1. The rare earth magnet according to claim 1, wherein R ² is Nd. Formula ^{_{(Nd x La y Ce z R}} 1 w) p Fe (100-p-q-r-s-t-u) Co q B r Ga s Cu t M 1 u ( provided that, ^{R 1} is, Nd, La , And one or more elements selected from the group consisting of rare earth elements other than Ce, and M ¹ is one or more elements selected from the group consisting of Al, Au, Ag, Zn, In, and Mn; Is an impurity element,
p, q, r, s, t, and u are 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, and
x, y, z, and w are molar ratios,
0.20≦x≦0.60,
0.40≦y≦0.70,
0≦z≦0.10,
0≦w≦0.10, and x+y+z+w=1
To prepare a molten metal having a composition represented by
Quenching the melt to obtain a ribbon or powder,
Hot compressing the ribbon or the powder to obtain a molded body, and hot working the molded body to obtain a plastically deformed body,
including,
Manufacturing method of rare earth magnet. Where x and y are
0.20≦x≦0.40 and 0.50≦y≦0.70
The method of claim 5, wherein R ² _a R ³ _b M ² _(1-a-b) (wherein R ² is one or more elements selected from the group consisting of Pr, Nd, Pm, Sm, Eu, and Gd, and R ³ is , R ² is one or more elements selected from the group consisting of rare earth elements other than R ² , and M ² is alloyed with R ² and R ³ to form R ² _a R ³ _b M ² _{(1-a-b )} Is one or more alloying elements and unavoidable impurity elements that lower the melting point of R ² below the melting point of R ² , and a and b are in a molar ratio of 0.50≦a≦0.80 and 0≦b≦ Providing a modifier containing an alloy of 0.10),
Contacting the plastic deformable body and the modifier with each other to obtain a contact body, and heat treating the contact body to allow the melt of the modifier to penetrate into the contact body.
including,
The method according to claim 5 or 6. The method of claim 7, wherein R ² is Nd.