JP2019169507A - Alloy for rare earth magnet - Google Patents

Abstract

To provide anisotropic magnetic powder with improved magnetic properties and thermal stability with high efficiency.SOLUTION: An alloy for a rare earth magnet according to the present disclosure has a main phase and one or more subphases, and the composition of the entire alloy is represented by the following composition formula (1). R(Fe,Co)TiCuSn(1). R is at least one rare earth element, and w, z, and α respectively satisfy 8≤w≤13, 0.42≤z<0.70, 0.35≤α≤0.82, and 0<β≤0.10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an alloy for rare earth magnets.

In recent years, there has been a demand for the development of a magnet with a reduced content of rare earth elements. In this specification, the rare earth element refers to at least one element selected from the group consisting of scandium (Sc), yttrium (Y), and lanthanoid. Here, the lanthanoid is a generic name of 15 elements from lanthanum (La) to lutetium (Lu). As a ferromagnetic alloy in which the composition ratio of the rare earth element is relatively small, RT ₁₂ having a body-centered tetragonal ThMn ₁₂ type crystal structure (where R is at least one rare earth element and T is Fe, Co or Ni) is Are known. RT ₁₂ has high magnetization, but has a problem that its crystal structure is thermally unstable.

  Patent Document 1 discloses a rare earth permanent magnet in which part of Fe as a T element is partially replaced by Ti as a structure stabilizing element, and the thermal stability is improved in exchange for high magnetization. Yes.

In Patent Document 2, the R element of the RFe _12- based compound is partially substituted with a substitution element M1 such as Zr or Hf, so that the amount of substitution element M2 such as Ti that substitutes the transition metal element is reduced and saturated. A rare earth permanent magnet is disclosed in which the ThMn ₁₂ structure is stabilized while maintaining the magnetization.

Patent Document 3 discloses an R′—Fe—Co based ferromagnetic alloy in which Y or Gd is selected as part of the R element of RFe ₁₂ , and this R′—Fe—Co based ferromagnetic alloy is disclosed. It is described that the alloy exhibits a high magnetic property because it has a ThMn ₁₂ type crystal structure formed by a rapid quenching method.

Patent Document 4 describes that addition of Cu produces a non-magnetic and low melting point 1-4 composition (SmCu ₄ phase), which enables sintering and high coercivity. .

Patent Document 5 discloses at least one of an Sm ₅ Fe ₁₇ phase, an SmCo ₅ phase, an Sm ₂ O ₃ phase, and an Sm ₇ Cu ₃ phase as a subphase with respect to a ThMn ₁₂ type main phase. It is described that inclusion thereof can increase the coercive force.

  Patent Document 6 describes that by adding Cu, a liquid phase is generated and a dense bulk body can be formed.

JP-A 64-76703 JP-A-4-322406 Japanese Patent Laying-Open No. 2015-156436 JP 2001-189206 A JP 2017-112300 A International Publication No. 2016/162990

  Single-crystal-like main phase particles used in anisotropic magnets that are widely used as high-performance magnets are obtained by high-efficiency pulverization of raw material alloys (substances to be crushed) to single-crystal units. . Furthermore, in consideration of a general processing temperature in the sintering step, the main phase compound is also required to be stably present at least 900 ° C. or more, preferably 1000 ° C. or more.

  Although the rare earth permanent magnet described in Patent Document 1 has improved thermal stability due to elemental substitution of Fe by Ti, since the amount of Fe substitution by Ti is large, magnetization is reduced by that amount, and sufficient magnetic properties are obtained. I can't get it.

On the other hand, in the rare earth permanent magnet described in Patent Document 2, although the ThMn ₁₂ structure is stabilized by substituting the transition metal element with Ti or the like, the effect is not necessarily sufficient.

  Since the R′-Fe—Co based ferromagnetic alloy described in Patent Document 3 does not substitute the Fe element with the structural stabilizing element M (Ti or the like), it has high magnetization, large magnetic anisotropy, and high Curie temperature. Although it is obtained, since it is a non-equilibrium phase, the main phase compound may decompose in a densification process at a high temperature such as sintering.

  In the rare earth magnet described in Patent Document 4, the magnetic property value may not be high due to the large amount of Ti added. Furthermore, since Cu dissolves in the main phase, there is a concern that saturation magnetization and magnetic anisotropy will decrease.

In the rare earth magnet described in Patent Document 5, when the rare-earth-rich subphase Sm ₇ Cu ₃ is used, there is a concern that the equilibrium state shifts to a rare-earth-rich composition rather than the main phase during heat treatment, and the main phase ratio decreases. Is done.

  In the rare earth magnet described in Patent Document 6, since the Fe element is not substituted with the structural stabilizing element M, high magnetization, large magnetic anisotropy and high Curie temperature can be obtained, and the density as a bulk body is high. Because of the non-equilibrium phase, the main phase compound may decompose in a process at a high temperature such as sintering at 1000 ° C. or higher. Furthermore, it is difficult to obtain anisotropic sintered magnetic powder.

  Accordingly, an object of the present disclosure is to provide a rare earth magnet alloy suitable for obtaining anisotropic sintered magnetic powder.

The rare earth magnet alloy of the present disclosure is an alloy for a rare earth magnet having a main phase and one or more subphases, and the composition of the entire alloy is represented by the following composition formula (1):
_{R (Fe, Co) w-} z Ti z Cu α Sn β (1)
R is at least one rare earth element, and w, z, and α are 8 ≦ w ≦ 13, 0.42 ≦ z <0.70, 0.35 ≦ α ≦ 0.82, and 0 <β, respectively. ≦ 0.10 is satisfied.

In one embodiment, R is composed of R1 and R2.
The overall composition is represented by the following composition formula (2):
_{R1 1-x R2 x (Fe} 1-y Co y) w-z Ti z Cu α Sn β (2)
R1 is Y or Y and Gd, Y is 50 mol% or more of R1 as a whole, R2 is at least one selected from the group consisting of Sm, La, Ce, Nd, and Pr, and necessarily includes Sm, Sm is 50 mol% or more of the entire R2, and x and y satisfy 0.5 ≦ x ≦ 1.0 and 0 ≦ y ≦ 0.4, respectively.

In one embodiment, the main phase has a crystal structure of ThMn ₁₂ type,
The composition of the main phase is represented by the following composition formula (3):
R1 _{1-x ′} R2 _{x ′} (Fe _{1-y ′} Co _{y ′} ) _{12-z′-α ′ Tiz ′} Cu _{α ′} (3)
x ′, y ′, z ′, and α ′ are 0.5 ≦ x ′ ≦ 1.0, 0 ≦ y ′ ≦ 0.4, 0.48 ≦ z ′ <0.91, and 0, respectively. .15 ≦ α ′ ≦ 0.30 is satisfied.
In some embodiments, z ′ satisfies 0.48 ≦ z ′ <0.74.

In one embodiment, the main phase is a phase having a ThMn ₁₂ type crystal structure, and the subphase is mainly composed of a crystal phase having a Cu composition and an Sn group crystal phase of 50 mol% or more of the total subphase.

In one embodiment, the subphase includes at least a Cu-based KHg ₂ type crystal structure phase or a Cu-based phase of a rare earth element and a 3d transition element in a molar ratio of 1: 4, and at least Sn. It includes a phase of the basic NdPtSb type crystal structure.

In one embodiment, the phase of KHg type ₂ crystal structure is 50% or more of the subphase by volume ratio.

  In one embodiment, the subphase includes R atoms, and the R atoms present in the subphase have a [R2] / ([R1] + [R2]) molar ratio higher than the composition of the entire alloy.

  In an embodiment, the composition formula ratio of the Cu-based subphase is 9 mol% or more and 27 mol% or less, and the Sn-based phase is less than the Cu-based phase.

  According to the embodiment of the present invention, anisotropic magnetic powder having improved magnetic properties and thermal stability can be obtained with high efficiency.

It is a figure which shows the observation result and composition analysis result of a polarization microscope cross-sectional structure | tissue after heat processing for 20 minutes at 1050 degreeC about the rare earth magnet alloy of Example 1 in embodiment of this indication. It is a figure which shows the backscattered electron (BSE) image obtained with the scanning electron microscope (SEM) after the heat processing for 20 minutes at 1050 degreeC about the rare earth magnet alloy of Example 1 in embodiment of this indication.

[Composition of rare earth magnet alloy]
In an exemplary and non-limiting embodiment, the rare earth magnet alloy of the present disclosure has a main phase and a subphase, and the overall composition is represented by the following composition formula (1).
_{R (Fe, Co) w-} z Ti z Cu α Sn β (1)
Here, R is at least one rare earth element. Further, w, z, and α satisfy 8 ≦ w ≦ 13, 0.42 ≦ z <0.70, 0.35 ≦ α ≦ 0.82, and 0 <β ≦ 0.10, respectively.

In an embodiment, the entire composition is represented by the following composition formula (2).
_{R1 1-x R2 x (Fe} 1-y Co y) w-z Ti z Cu α Sn β (2)
Here, R is composed of R1 and R2. R1 is Y or Y and Gd, Y is 50 mol% or more of R1 as a whole, R2 is at least one selected from the group consisting of Sm, La, Ce, Nd, and Pr, and necessarily includes Sm, Sm is 50 mol% or more of the entire R2. R1 is preferably only Y (excluding inevitable impurities), and R2 is preferably only Sm (excluding inevitable impurities). x, y, z, and w are 0.5 ≦ x ≦ 1.0, 0 ≦ y ≦ 0.4, 8 ≦ w ≦ 12, 0.42 ≦ z <0.70, and 0.35 ≦ α, respectively. ≦ 0.82 and 0 <β ≦ 0.10 are satisfied.

  By including Sm in the rare earth element R, the magnetic anisotropy of the main phase, which is important for increasing the coercive force, can be improved.

  As a result of intensive studies by the present inventors, as shown in the above composition formulas (1) and (2), by adding Cu to the raw material alloy, the molten alloy of the raw material alloy is rapidly cooled and solidified in the alloy. It was found that a rare earth-rich phase (subphase) coexisting with the main phase (hard magnetic phase having high magnetization and magnetic anisotropy) was formed. It has been found that the generation of a sub-phase rich in rare earth than the main phase makes it possible to easily grow the main phase by heat treatment performed on the rapidly solidified alloy. In addition, this heat treatment makes it possible to easily reduce foreign phases during melting and solidification of the raw material alloy. Furthermore, when the rare earth-rich subphase absorbs and releases hydrogen, cracks occur between the main phase and the subphase or in the subphase, and the single crystal unit can be efficiently pulverized. These are extremely useful in obtaining anisotropic sintered magnetic powder, and can enable mass production of highly sintered anisotropic sintered magnetic powder.

  The amounts of R1, R2 and Ti affect the magnetic properties and high temperature stability of the main phase. From the viewpoint of magnetic anisotropy, R2 is desirably half or more than R1 (half or more of the entire R), and a preferable range of x is 0.5 ≦ x ≦ 1.0. Further, Ti is preferably as small as possible from the viewpoint of saturation magnetization, but more is desirable from the viewpoint of high-temperature stability. A range of 0.42 ≦ z <0.70 is appropriate. In particular, when z is 0.70 or more, the saturation magnetization, the magnetic anisotropy magnetic field, and the Curie temperature all decrease. Note that 50 mol% or less of Ti may be substituted with tungsten (W), vanadium (V), or the like.

  Moreover, it is preferable to replace a part of Fe with Co from the viewpoints of an increase in magnetic moment and an increase in magnetization at a practical temperature accompanying an increase in Curie temperature and an improvement in magnetic anisotropy. However, if the amount of substitution by Co is too large, the magnetization and magnetic anisotropy are reduced. Specifically, the Co substitution amount y is preferably 0 ≦ y ≦ 0.4, and more preferably 0.1 ≦ y ≦ 0.3.

  The amount of Cu is set so that the amount of the subphase to be generated becomes an appropriate value. When the amount of the subphase is small, not only the heterogeneous phase at the time of melting and solidifying the raw material alloy cannot be lost, but also it is not easy to grow the crystal to a size sufficient to obtain anisotropic sintered magnetic powder. Moreover, since the ratio of a main phase will fall when there is much quantity of a subphase, the magnetization as a magnet body will fall. According to the inventor's experiment, the appropriate amount of Cu is in the range of 0.35 ≦ α ≦ 0.82.

  The amount of Sn is important because it determines the amount of Cu dissolved in the main phase to be generated. Addition of Sn generates a phase having a crystal structure of at least NdPtSb type (1-1-1 phase), and changes in Cu distribution. If the added amount of Sn is small, the amount of Cu solid solution in the main phase is large, which is not preferable in terms of saturation magnetization and magnetic anisotropy, and if the added amount of Sn is large, the 1-1-1 phase that does not dissolve the main phase is large. It is not easy to inhibit crystal growth and reduce heterogeneous phases. Therefore, the range of 0 <β ≦ 0.10 is appropriate.

The subphases generated are 50 mol% or more of the total subphase being a crystalline phase having a Cu composition (that is, a Cu group that is R richer than the main phase) and a Sn group. In an embodiment, the phase of the subphase Cu group is mainly a phase having a crystal structure of KHg ₂ type (hereinafter referred to as 1-2 phase). The subphase may also include a phase having a composition (hereinafter referred to as a 1-4 composition) in which the ratio of “R” to “Cu, Fe, and / or Co” is 1: 4. On the other hand, the phase of the Sn group mainly includes a phase having a crystal structure of NdPtSb type. Regarding the R element constituting the subphase, in both phases, the molar ratio [R2] / ([R1] + [R2]) is higher than the composition of the entire alloy. In the subphase, Fe and Co may be slightly dissolved. Ti dissolves in a very small amount in the Sn group phase.

  The appropriate amount of w varies depending on the amount of Cu added to the raw material alloy, but 8 ≦ w ≦ 13. If w is too large, a soft magnetic α- (Fe, Co, Ti) phase is generated. If w is too small, a 2-17 phase or a 3-29 phase is generated. Neither of these phases is preferred for obtaining a magnet with high magnetic properties.

Thus the main phase of the _RT w Ti _z Cu _α Sn _β of the rare earth magnet alloy obtained, in embodiments, has a ThMn ₁₂ type crystal structure. The TnMn ₁₂ type compound phase in the alloy in the present disclosure can typically exist stably even at 1000 ° C. or higher. For this reason, the embodiments of the alloy of the present disclosure can be suitably used to adopt a high-performance magnet manufacturing process such as a sintering method.

In general, the “ThMn ₁₂ type crystal structure” is a tetragonal crystal. However, in the present invention, the tetragonal crystal lattice is slightly distorted to have orthorhombic symmetry, and the atoms in the crystal. Even when the periodicity is slightly disturbed, it is regarded as a “ThMn _12- type crystal structure”.

Since the main phase to be produced contains Cu, the magnetic property values are different even with the same Ti substitution amount when compared with the main phase not containing Cu. However, the amount of Cu solid solution in the main phase can be suppressed by adding Sn during dissolution. First, the saturation magnetization is lowered by at least a solid solution of Cu and Ti. The magnetic anisotropy magnetic field exhibits complicated behavior as co-substitution of Cu and Ti. Specifically, contrary to the general characteristics of a compound of ThMn ₁₂ type crystal structure in which Cu is not substituted, the magnetic anisotropic magnetic field tends to decrease with the addition of Ti. Therefore, both Cu and Ti are preferably as small as possible from the viewpoint of magnetic property values for both elements. However, from the viewpoint of high temperature stability, a larger amount of Ti is desirable. Specifically, when the main phase is expressed by the composition formula R1 _{1-x ′} R2 _{x ′} (Fe _{1−y ′} Co _{y ′} ) _{12−z′−α ′ Tiz ′} Cu _{α ′} , 0.5 ≦ x ′ ≦ 1.0, 0 ≦ y ′ ≦ 0.4, 0.48 ≦ z ′ <0.91, 0.15 ≦ α ′ ≦ 0.30 are appropriate, and the substitution amount of Cu and Ti is More preferably, 0.48 ≦ z ′ <0.74 and 0.15 ≦ α ′ ≦ 0.30.

[Production method of rare earth magnet alloy]
<Step A> Step of melting and solidifying Known methods such as a die casting method, a centrifugal casting method, a strip casting method, and a liquid ultra-quenching method as a method for producing an R-Fe-Co-Ti-Cu rare earth magnet alloy The method can be adopted. In these methods, after preparing a molten alloy, the molten metal is cooled and solidified. It is desirable to suppress as much as possible the generation of an unfavorable phase (heterophase) as a raw material alloy for magnets such as an α- (Fe, Co, Ti) phase during solidification of the molten alloy. By adopting a method of producing a ribbon or flake-like alloy by supplying molten metal onto a rotating roll and solidifying it, such as a strip casting method or a liquid ultra-quenching method, which has a relatively high cooling rate. Generation can be suppressed. When the cooling rate at the time of solidification is low, the grain size of the different phase that precipitates increases. When the grain size of the heterogeneous phase contained in the alloy becomes large, it is difficult for the heterogeneous phase to disappear in the heat treatment step of the next step B.

  When the molten alloy is rapidly cooled and solidified at a high cooling rate as in the liquid superquenching method, “nanocrystals” having a size on the order of nanometers are formed in the alloy after solidification. In the “nanocrystal” state, anisotropic magnetic powder cannot be obtained even when the solidified alloy is pulverized. However, even nanocrystals can be easily grown into crystal grains having a size of 10 μm or more suitable for obtaining anisotropic magnetic powder by performing the heat treatment step of the subsequent step B.

<Step B> Heat treatment step By applying a heat treatment to the alloy of the present invention, the following can be realized.
(1) Reduce the amount of heterogeneous phase generated during the solidification process.
(2) The crystal grains are coarsened. This is effective for easily obtaining a powder composed of single crystal-like particles useful as a raw material for an anisotropic sintered magnet by a pulverization method.

  Although it depends on the composition of the alloy, the melting point of the 1-2 phase is around 860 ° C., and the melting point of the phase of the 1-4 composition is around 880 ° C. The melting point of the 1-1-phase of the Sn group is 1000 ° C. or higher. In addition, since the phase of Sn group hardly dissolves the main phase, it does not contribute to the crystal growth of the main phase. Therefore, the heat treatment temperature is preferably 900 ° C. or higher and 1250 ° C. or lower, and more preferably 1000 ° C. or higher and 1100 ° C. or lower.

  The heat treatment time is preferably from 5 minutes to 50 hours, depending on the heat treatment temperature. If the time is too short, the reaction may not be sufficient to eliminate the heterogeneous phase, or the grain growth may be insufficient. If the time is too long, evaporation and oxidation of rare earth elements occur, and the operational efficiency is poor. At this heat treatment temperature, at least a part of the subphase becomes a liquid phase and a part of the main phase is dissolved and reprecipitated. For this reason, crystal grains grow dramatically in the main phase compared to the case where no liquid phase is generated. Also, the heterogeneous phase generated during the rapid solidification of the molten alloy can be easily eliminated if the grain size is not large.

  The amount of the subphase in the alloy before performing Step B is desirably 9 mol% or more and 27 mol% or less. If the amount of the subphase is small, not only the heterogeneous phase in the alloy cannot be lost even by the heat treatment in Step B, but it is not easy to grow the crystal to a size sufficient to obtain anisotropic sintered magnetic powder. Moreover, since the ratio of a main phase will fall when there is much quantity of a subphase, the magnetization as a magnet body will fall. The alloy thus obtained can be used as a rare earth magnet alloy that can be efficiently pulverized into single crystal units by hydrogen embrittlement.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

[Example 1]
<Process A>
Y, Sm, Fe, Co, Ti, Cu, and Sn raw metals having a purity of 99.9% or more were weighed in steps, taking into account the evaporation of rare earth elements during melting. These raw metals are sufficiently melted in a tapping pipe of a liquid ultra-quenching device (melt spinning device) to form a molten alloy, and then the molten metal is tapped onto a Cu roll rotating at a roll peripheral speed of 15 m / s. did. The molten metal contacted the surface of the roll rotating at a high speed and was quickly removed from the heat, and extended into a ribbon shape and solidified. In Example 1 and Comparative Example 2, the molten metal was discharged on a Cu roll rotating at 15 m / s, and in Comparative Example 1, the molten metal was discharged on a Cu roll rotating at 40 m / s. Thus, ultra-quenched ribbons having the compositions shown in Table 1 were produced.

<Process B>
The ultra-quenched ribbon produced in step A was included in the Nb foil, and heat treatment was performed at 1050 ° C. for 20 minutes in an Ar flow.

  Tables 1 and 2 show the composition of the alloy, the composition of the main phase identified by SEM-EDX analysis, and the saturation magnetization Ms (T), magnetic anisotropy field Ha (T), and Curie temperature Tc (° C.) at room temperature. Indicates. However, the saturation magnetization and the magnetic anisotropic magnetic field were evaluated using a vibrating sample magnetometer capable of applying a magnetic field up to 10T. Since the magnetic powder is isotropic, the saturation magnetization was identified using the square law saturation asymptotic law, and the magnetic anisotropy field was identified using the singular point detection method. The Curie temperature was defined as the inflection point of the temperature change of magnetization using a thermomagnetic balance.

  As shown in Table 2, the main phase of Comparative Example 1 has a high saturation magnetization and a magnetic anisotropic magnetic field. However, since Cu is not added as described above, a rare earth-rich phase that coexists with the main phase is not generated, and crystal growth of the main phase by heat treatment becomes difficult. Furthermore, cracks cannot be generated between the main phase and the subphase, and the single crystal unit cannot be efficiently pulverized. Therefore, it is not possible to produce anisotropically sintered magnet powder that can be highly oriented. Further, by adding Cu, an anisotropic sintered magnet powder that can be highly oriented can be produced. However, as shown in Comparative Example 2 of Table 2, the saturation magnetization and the magnetic anisotropic magnetic field of the main phase are reduced. End up. On the other hand, in Example 1 of the present invention, the amount of Cu solid solution in the main phase is reduced by adding Sn as compared with Comparative Example 1 in which Sn is not added, and the main phase has high saturation magnetization and high magnetic properties. It becomes possible to have an anisotropic magnetic field.

  FIG. 1 shows the observation result of the cross-sectional structure of the polarizing microscope after the heat treatment at 1050 ° C. for 20 minutes for the rare earth magnet alloy of Example 1. FIG. 2 shows a backscattered electron (BSE) image obtained by a scanning electron microscope (SEM) after the heat treatment at 1050 ° C. for 20 minutes for the rare earth magnet alloy of Example 1. Table 3 shows the result of composition analysis by SEM-EDX.

  From this result, it can be seen that by heat treatment, microcrystals on the order of several hundred nm grow into coarse crystal grains of 10 μm or more. Moreover, it turns out that the subphase contains the 1-2 phase of Cu group, the phase of 1-4 composition, and the 1-1-1 phase of Sn group. At least the three subphases described above have a composition richer in Sm than the Y / Sm ratio of the entire alloy. From powder X-ray diffraction, it was confirmed that the 1-1-1 phase was an NdPtSb type phase.

[Examples 2 to 5]
<Process A>
Evaporation of rare earth elements during melting so that the raw materials of Y, Sm, Fe, Co, Ti, Cu and Sn having a purity of 99.9% or more have the compositions shown in Comparative Examples 3 to 5 and Examples 2 to 5 And weighed in increments. After sufficiently dissolving in the tapping pipe, the molten metal was poured out on a Cu roll rotating at 15 m / s, and ultra-quenched ribbons were respectively produced.

<Process B>
The ultra-quenched ribbon produced in step A was included in the Nb foil, and heat treatment was performed at 1050 ° C. for 20 minutes in an Ar flow.

  Table 4 shows the amount of the main phase, the amount of the secondary phase and the alloy composition after the heat treatment, the Cu intrinsic amount of the main phase after the heat treatment, and the presence / absence of a different phase after the heat treatment. In each of Examples 2 to 5 of the present invention, the Cu intrinsic amount of the main phase is smaller than those of Comparative Examples 3 to 5. In Comparative Examples 3 to 5, it can be seen that the volume magnetization and the magnetic anisotropic magnetic field are not high because the amount of Cu solid solution in the main phase is large. When Example 2 and Example 3 are compared with each other, the amount of Cu solid solution in the main phase is small and the volume magnetization and magnetic anisotropy field are large. In Example 2, the Sn-based phase is more than half of the Cu-based phase. Therefore, the foreign phase cannot be lost. This can also be seen by comparing Example 4 and Example 5 with a large amount of subphase. Therefore, the Sn group phase is preferably less than half of the Cu group phase.

  The rare earth magnet alloy of the present disclosure includes a main phase with improved magnetic properties and thermal stability and a rare earth-rich subphase, and therefore can be suitably used for the production of anisotropic sintered magnetic powder. The anisotropic sintered magnetic powder can be suitably used for producing a sintered magnet. Sintered magnets are used in various motors and actuators and have various industrial applications.

Claims (9)

An alloy for a rare earth magnet having a main phase and one or more subphases, wherein the composition of the entire alloy is represented by the following composition formula (1):
_{R (Fe, Co) w-} z Ti z Cu α Sn β (1)
R is at least one rare earth element,
w, z, and α are respectively 8 ≦ w ≦ 13,
0.42 ≦ z <0.70,
0.35 ≦ α ≦ 0.82, and 0 <β ≦ 0.10
Satisfying rare earth magnet alloys. R is composed of R1 and R2,
The overall composition is represented by the following composition formula (2):
_{R1 1-x R2 x (Fe} 1-y Co y) w-z Ti z Cu α Sn β (2)
R1 is Y or Y and Gd, Y is 50 mol% or more of the entire R1,
R2 is at least one selected from the group consisting of Sm, La, Ce, Nd and Pr, Sm is necessarily included, and Sm is 50 mol% or more of the entire R2,
x and y are respectively
0.5 ≦ x ≦ 1.0,
0 ≦ y ≦ 0.4,
The alloy for rare earth magnets according to claim 1, wherein The main phase has a ThMn ₁₂ type crystal structure,
The composition of the main phase is represented by the following composition formula (3):
R1 _{1-x ′} R2 _{x ′} (Fe _{1-y ′} Co _{y ′} ) _{12-z′-α ′ Tiz ′} Cu _{α ′} (3)
x ′, y ′, z ′, and α ′ are respectively
0.5 ≦ x ′ ≦ 1.0,
0 ≦ y ′ ≦ 0.4,
0.48 ≦ z ′ <0.91, and
The alloy for rare earth magnets according to claim 1 or 2, satisfying 0.15≤α'≤0.30. z ′ is 0.48 ≦ z ′ <0.74.
The alloy for rare earth magnets according to claim 3, wherein: The main phase is a phase having a ThMn ₁₂ type crystal structure,
5. The rare earth magnet alloy according to claim 1, wherein the subphase is mainly composed of a Cu-composition crystal phase and a Sn-based crystal phase at 50 mol% or more of the total subphase. The subphase includes at least a Cu-based KHg ₂ type crystal structure phase or a Cu-based phase in which the composition of a rare earth element and a 3d transition element is 1: 4 in a molar ratio, and at least a Sn-based NdPtSb type. The rare earth magnet alloy according to claim 5, comprising a phase having a crystal structure. The rare earth magnet alloy according to claim 6, wherein the phase of the KHg ₂ type crystal structure is 50% or more of the subphase by volume ratio.   The subphase includes R atoms, and the R atoms present in the subphase have a molar ratio [R2] / ([R1] + [R2]) higher than the composition of the entire alloy. The alloy for rare earth magnets according to claim 1.   9. The rare earth magnet alloy according to claim 5, wherein the composition formula ratio of the Cu-based subphase is 9 mol% or more and 27 mol% or less, and the Sn-based phase is smaller than the Cu-based phase.