KR102077147B1 - Rare-earth magnet - Google Patents

Abstract

Provided is a rare earth magnet in which a 1-5 phase is stabilized even when a part of Co is substituted with Fe by using Ce as at least a part of the rare earth elements, and a manufacturing method thereof.
Formula (Ce _x La _(1-xw) R ' _w ) _v (Co _y Fe _(1-y) ) _(100-vz) M _z (In the formula, R' is one or more rare earths other than Ce and La. Is an element, and M is one or more selected from the group consisting of transition metal elements other than Co and Fe, and Ga, Al, Zn, and In, and is an unavoidable impurity element, and 0 <x <1.0, 0 a rare earth magnet having a composition represented by <y <1.0, 0≤w≤0.17, 1≤v≤20.9, and 0≤z≤8.0, and satisfying the relationship of y≥-3x + 1.7 in the above formula, and Its manufacturing method.

Description

Rare Earth Magnets {RARE-EARTH MAGNET}

The present disclosure relates to a rare earth magnet and a manufacturing method thereof. The present disclosure relates to a rare earth magnet including a magnetic phase having a composition represented by RT ₅ (R is a rare earth element and T is a transition metal element) and a method of manufacturing the same.

The application of permanent magnets extends to a wide range of fields such as electronics, information and communication, medical care, machine tool fields, and industrial and automotive motors. In addition, the demand for suppression of carbon dioxide emissions is increasing, and in recent years, the expectation for the development of permanent magnets having high characteristics is increasing due to the spread of hybrid cars, energy saving in industrial fields, and improvement in power generation efficiency.

At present, Nd-Fe-B magnets, which are dominant in the market as high-performance magnets, are also used in magnets for drive motors for HV / EHV. In recent years, in response to the further miniaturization and high output of motors being pursued, the development of new permanent magnet materials is in progress.

As one of the developments of materials having a performance superior to that of Nd-Fe-B magnets, research on rare earth magnets having a binary magnetic phase of rare earth elements and transition metal elements has been conducted.

For example, Patent Document 1 has a composition of R (Fe _(1-p) Co _p ) _q A _r (R is one or more of Sm or Ce, 0.1≤p≤0.6, 4≤q≤6, 0.1≤ A rare earth magnet is disclosed, which has a hexagonal CaCu ₅ structure whose main phase is a hexagonal CaCu ₅ structure and has interstitial intercalating atoms.

Japanese Patent Laid-Open No. 4-371556

In the binary system of the rare earth element and the transition metal element, magnetic phases in which the molar ratio of the rare earth element and the transition metal element are 1: 2, 1: 5, 1:12, 2: 7, 2:17 and the like are known. In addition, in the following description, these magnetic phases may respectively be called 1-2 phase, 1-5 phase, 1-12 phase, 2-7 phase, 2-17 phase, etc., respectively.

In the binary system of the rare earth element and the transition metal element, when the rare earth element is Sm and the transition metal element is Co, phases 1-5 are 1-2, 1-12, 2-7, and 2-17. It is known that it is thermally stable than a phase. Therefore, the rare earth magnet containing Sm and Co contains many SmCo ₅ phases.

Since Sm has high scarcity among the rare earth elements, it has been attempted to replace a part or all of Sm with a rare earth element having a lower scarcity than Sm.

In the rare earth magnet disclosed in Patent Document 1, at least a part of Sm is substituted with Ce. However, (Sm, Ce) Co ₅ has a lower saturation magnetization than SmCo ₅ . In order to compensate for the saturation magnetization lowered by the substitution of Sm by Ce, at least part of Co is substituted with Fe. However, when Co is substituted with Fe, (Sm, Ce) (Co, Fe) ₅ becomes remarkably unstable than (Sm, Ce) Co ₅ . As a result, in the rare earth magnets, the content of the 1-5 phase represented by (Sm, Ce) (Co, Fe) ₅ is significantly reduced, and the 1-2 phase represented by (Sm, Ce) (Co, Fe) ₂ is remarkably reduced. Increases. As a result, both the saturation magnetization and the anisotropic magnetic field are lowered. Therefore, in the rare earth magnet of Patent Document 1, even when at least a part of Co is substituted with Fe, C and N are introduced into the 1-5 phases in an invasive manner in order to stabilize the 1-5 phases.

However, since it is difficult to introduce C and N to the core portion of the 1-5 phase, it is difficult to stabilize the 1-5 phase as a whole of the rare earth magnet. In addition, since the 1-5 phase into which C and N are introduced is easy to decompose when it becomes 400 degreeC or more, it is inferior to high temperature stability.

From these, when Ce is used for at least a part of the rare earth elements and a part of Co is substituted with Fe, 1-5 phase becomes an unstable phase, 1-2 phase becomes a stable phase, and 1-5 phase in a rare earth magnet MEANS TO SOLVE THE PROBLEM The present inventors discovered the subject that it is difficult to contain this. In addition, even if C and N are introduced into the magnetic phase in order to stabilize the 1-5 phase, the 1-5 phase cannot be sufficiently stabilized, and at the high temperature, the 1-5 phase is decomposed. The inventors have discovered.

Disclosure of Invention The present disclosure has been made to solve the above problems, and provides a rare earth magnet in which 1-5 phases are stabilized even when Ce is used for at least a part of the rare earth elements and a part of Co is replaced with Fe, and a method of manufacturing the same For the purpose of

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined and completed the rare earth magnet of this indication, and its manufacturing method in order to achieve the said objective. The gist is as follows.

<1> Formula (Ce _x La _(1-xw) R ' _w ) _v (Co _y Fe _(1-y) ) _(100-vz) M _z

(In the formula, R 'is one or more rare earth elements other than Ce and La,

M is a transition metal element other than Co and Fe, at least one selected from the group consisting of Ga, Al, Zn, and In, and an unavoidable impurity element,

0 <x <1.0,

0 <y <1.0,

0≤w≤0.1,

7.1≤v≤20.9, and

0≤z≤8.0)

Has the composition represented by

In the above formula, satisfying the relationship of y≥-3x + 1.7,

Rare earth magnets.

<2> The rare earth magnet according to <1>, further satisfying the relationship of y≤-1.25x + 1.25 in the above formula.

<3> The rare earth magnet according to <1> or <2>, in which x satisfies 0.3 ≦ x ≦ 0.9.

<4> The rare earth magnet according to <1> or <2>, in which x satisfies 0.6≤x≤0.9.

<5> The rare earth magnet according to any one of <1> to <4>, in which y is 0.1 ≦ y ≦ 0.9.

<6> The rare earth magnet according to any one of <1> to <4>, in which y satisfies 0.1≤y≤0.7.

<7> The rare earth magnet according to any one of <1> to <4>, in which y satisfies 0.3 ≦ y ≦ 0.9.

<8> The rare earth magnet according to any one of <1> to <4>, in which y satisfies 0.3 ≦ y ≦ 0.7.

<9> Formula (Ce _x La _(1-xw) R ' _w ) _v (Co _y Fe _(1-y) ) _(100-vz) M _z

(In the formula, R 'is one or more rare earth elements other than Ce and La,

M is a transition metal element other than Co and Fe, at least one selected from the group consisting of Ga, Al, Zn, and In, and an unavoidable impurity element,

0 <x <1.0,

0 <y <1.0,

0≤w≤0.1,

7.1≤v≤20.9, and

0≤z ≤8.0)

Preparing a molten metal having a composition represented by the above formula and satisfying a relationship of y≥-3x + 1.7 in the above formula, and

A method for producing a rare earth magnet, which comprises rapidly cooling the molten metal at a rate of 1 × 10 ² to 1 × 10 ⁷ K / sec to obtain a thin ribbon.

<10> The method according to <9>, wherein, in the above formula, the relationship of y≤-1.25x + 1.25 is further satisfied.

<11> The method according to <9> or <10>, in which x satisfies 0.3 ≦ x ≦ 0.9.

<12> The method according to <9> or <10>, in which x satisfies 0.6 ≦ x ≦ 0.9.

<13> The method according to any one of <9> to <12>, in which y satisfies 0.1 ≦ y ≦ 0.9.

<14> The method according to any one of <9> to <12>, in which y satisfies 0.1 ≦ y ≦ 0.7.

<15> The method according to any one of <9> to <12>, in which y satisfies 0.3 ≦ y ≦ 0.9.

<16> The method according to any one of <9> to <12>, in which y satisfies 0.3 ≦ y ≦ 0.7.

According to the present disclosure, in a binary rare earth magnet of a rare earth element and a transition metal element, by coexisting Ce and La, a rare earth magnet in which 1-5 phases are stabilized even when a part of Co is substituted with Fe is provided, and a manufacturing method thereof. can do.

1 is a diagram in which the results of Table 1 are written together in the formation energy map.
2 is a diagram in which the results of Table 1 are written together in the total magnetic moment map.
3 is a schematic diagram of an apparatus used for the strip cast method.
4 is a diagram showing an XRD analysis result for samples of Examples 1 to 5. FIG.
It is a figure which shows the XRD analysis result about the sample of Comparative Examples 1-4.
6 is a diagram illustrating a result of calculating formation energy of various magnetic phases.
It is a figure which shows the XRD analysis result about the sample of Examples 6-9.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the rare earth magnet of this indication and its manufacturing method is demonstrated in detail. In addition, embodiment shown below does not limit the rare earth magnet of this indication, and its manufacturing method.

In the binary rare earth magnet of the rare earth element and the transition metal element, when the transition metal element is Co, 1-5 phases are stabilized. When the rare earth elements of the 1-5 phase are rare earth elements other than light rare earth elements such as Sm, Nd, Pr, Dy, and Tb, the 1-5 phase shows good saturation magnetization.

Sm, Nd, Pr, Dy, Tb, and the like have a higher scarcity than light rare earth elements such as Ce. For this reason, Sm, Nd, Pr, Dy, Tb, etc. are substituted by Ce (Hereinafter, it may be called "Ce substitution."). By Ce substitution, the saturation magnetization of the 1-5 phases falls. In order to compensate for this drop in saturation magnetization, Co is substituted with Fe (hereinafter, referred to as "Fe substitution"). Saturation magnetization improves by Fe substitution, but 1-5 phase becomes an unstable phase, 1-2 phase becomes a stable phase, and content of the 1-5 phase in a rare earth magnet falls. The 1-2 phase is inferior to both the saturation magnetization and the anisotropic magnetic field compared to the 1-5 phase.

In view of this, when Ce is used as a rare earth element, it is difficult to obtain a rare earth magnet containing 1-5 phases.

In the rare earth magnets, the present inventors make the CeFe ₂ phase unstable by coexisting Ce and La when a part of Co is substituted with Fe to stabilize the (Ce, La) (Co, Fe) ₅ phase. I found out that I could. Moreover, the present inventors discovered that the ratio (molar ratio) of Ce and La and the ratio (molar ratio) of Co and Fe which 1-5 phases are stabilized from the formation energy of a magnetic phase can be estimated. In addition, the (Ce, La) (Co, Fe) ₅ phase means a CeCo ₅ phase, a part of Ce is substituted by La and a part of Co is substituted by Fe.

In addition, in this specification, when "1-5 phase" shows a magnetic phase as (Ce, La) (Co, Fe) _t phase, for example, the phase whose t is 4-6 as a whole magnetic phase. Say The fact that t is 4-6 means that the magnetic phase may contain incomplete 1-5 phases in part. In this respect, it is preferable that t is 4.5-5.5. In these respects, "(Ce, La) (Co, Fe) _t is a magnetic phase (where t is 4 to 6, preferably 4.5 to 5.5)" and "(Ce, La) (Co, Fe) Magnetic phase containing ₅ ) "means the same.

The rare earth magnet of the present disclosure and its manufacturing method, which have been completed by the findings and the like described so far, will be described next.

<< rare earth magnet >>

Rare-earth magnet of the present disclosure, having a composition represented by the formula _{(Ce x La (1-xw} ) R 'w) v (Co y Fe (1-y)) (100-vz) M z. This formula represents the total composition of the rare earth magnet of the present disclosure.

In the above formula, Ce is cerium, La is lanthanum, R 'is at least one rare earth element other than Ce and La, Co is cobalt, and Fe is iron. M is one or more types selected from the group consisting of transition metal elements other than Co and Fe, and Ga, Al, Zn, and In, and an unavoidable impurity element. Ga represents gallium, Al represents aluminum, Zn represents zinc, and In represents indium. The transition metal element is an element between the Group 3 elements and the Group 11 elements in the periodic table.

x and w, respectively, Ce _x La _(1-xw) the content of the R 'at the time when the rare earth sites in total represented by _w 1, Ce and R' (molar ratio). At the rare earth site, La is the balance of Ce and R '.

y is a content ratio (molar ratio) of Co when the whole iron group site represented by Co _y Fe _(1-y) is 1. At the iron group site, Fe is the balance of Co.

v and z are content (atomic%) of the rare earth site and M, when the whole rare earth magnet of this indication is 100 atomic%, respectively. In the above-described formula, since the content (atomic%) of the iron group site is 100-v-z, the iron group site is the remainder of the rare earth site and M in the entire rare earth magnet.

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

<Ce>

Ce is a rare earth element and is an essential component in the rare earth magnet of the present disclosure in order to express its characteristics as a permanent magnet. Ce is a light rare earth element and has a lower rarity than a medium rare earth element and a heavy rare earth element. In a conventional rare earth magnet, when a light rare earth element such as Ce is used alone, it is difficult to contain 1-5 phases in the rare earth magnet. However, the rare earth magnet of the present disclosure can stabilize 1-5 phase by coexisting Ce and La, and can contain 1-5 phase in a rare earth magnet.

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

<La>

In the rare earth magnet, La coexists with Ce, thereby making the CeFe ₂ phase unstable and making the (Ce, La) (Co, Fe) ₅ phase stable. Accordingly, in the rare-earth magnet, decreasing the content on the CeFe _2, and (Ce, La) (Co, Fe) on the increase in the content _{of 5.} Phase 1-5 has higher saturation magnetization and anisotropic magnetic field than phase 1-2. Moreover, when it is 1-5 phases and the kind of rare earth elements is the same, the more content of Fe, the higher the saturation magnetization. From this point of view, the content of the (Ce, La) (Co, Fe) ₅ phase is increased to compensate for the saturation magnetization reduced by Ce substitution.

<R '>

R is one or more rare earth elements other than Ce and La. The rare earth magnet of the present disclosure is obtained by coexisting Ce and La. In the raw materials of Ce and La, it is difficult to make no rare earth element R 'other than Ce and La. However, in the rare-earth site represented by _{Ce x La (1-xw)} R 'w, if the value of w 0 to 0.1, and also think that characteristics of the rare-earth magnet of the present disclosure, w is the time 0, substantially equal to do.

Excessively increasing the purity of the raw materials of Ce and La causes an increase in the manufacturing cost, so the value of w may be 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more. In addition, the value of w may be low as long as the purity of the raw materials of Ce and La does not rise excessively, and the value of w may be 0.09 or less, 0.08 or less, 0.07 or less, or 0.06 or less.

<Rare earth site>

The total content of Ce, La, and R 'is represented by the content v (atomic%) of the rare earth site represented by Ce _x La _(1-xw) R'.

The rare earth magnet of the present disclosure is a binary system of a rare earth element and a transition metal element. In such binary systems, known magnetic phases include 1-2 phases, 1-5 phases, 1-12 phases, 2-7 phases, and 2-17 phases. When these magnetic phases are arranged in order of the high content of rare earth elements (in the order of rare earth rich), they are 1-2 phase, 2-7 phase, 1-5 phase, 2-17 phase, and 1-12 phase.

In the rare earth magnet of the present disclosure, the content v (atomic%) of the rare earth site is determined to contain 1-5 phases.

When the value of v is 7.1 atomic% or more, it is difficult to form magnetic phases containing less rare earth elements than the 1-5 phases, that is, 2-17 phases and 1-12 phases, and as a result, the 1-5 phases are stable. It becomes easy to be. From the viewpoint of making it difficult to form a magnetic phase with less content of rare earth elements than 1-5 phase, the value of v is preferably 9.0 atomic% or more, more preferably 12.0 atomic% or more, and more preferably 14.0 atomic% or more Preferably, 16.0 atomic% or more is more preferable, and 17.0 atomic% or more is further more preferable. In addition, by setting the value of v in this manner, the content of the iron group site can be reduced. As a result, the α-Co phase, the α-Fe phase, and the α- (Co, Fe) phase also become difficult to form. In addition, the (alpha)-(Co, Fe) phase shows the phase by which one part of Co of the (alpha) -Co phase is substituted by Fe.

On the other hand, if the value of v is 20.9 atomic% or less, it is difficult to form magnetic phases containing more rare earth elements than the 1-5 phases, that is, 1-2 phases and 2-7 phases, and as a result, 1-5 The phase becomes easy to stabilize. From the viewpoint of making it difficult to form a magnetic phase having a higher content of rare earth elements than 1-5 phase, the value of v is preferably 20.0 atomic% or less, more preferably 19.0 atomic% or less, and further 18.0 atomic% or less desirable.

<Co>

As described above, the rare earth magnet of the present disclosure is a binary system of a rare earth element and a transition metal element. As a transition metal element, Co is included with Fe demonstrated next. The rare earth element and the transition metal element can form an intermetallic compound phase (1-5 phase) in a molar ratio of 1: 5. Since 1-5 phase is especially stable when Co is a transition metal element, Co is essential in the rare earth magnet of this indication. By making Co essential, 1-5 phases become easy to contain in a rare earth magnet. Moreover, Co can also improve the Curie point of a rare earth magnet.

However, in the rare earth magnet of the present disclosure, in addition to Co, Fe is essential as a transition metal element. The reason is explained next.

<Fe>

As mentioned above, 1-5 phase has higher saturation magnetization and anisotropic magnetic field than 1-2 phase. In addition, in the 1-5 phase, if the kind of rare-earth element R is the same, RFe ₅ phase has larger saturation magnetization than RCo ₅ phase. In the rare earth magnet of the present disclosure, since both Ce and La are contained as rare earth elements, even if a part of Co in the RCo ₅ phase is replaced with Fe, the 1-2 phase is not stabilized, and the 1-5 phase is stable. In this manner, in the rare earth magnet, the content of the 1-5 phases with high saturation magnetization and anisotropic magnetic field can be increased.

<Tribal site>

The sum total content of Co and Fe demonstrated so far is represented by content of the iron group site represented by Co _y Fe _(1-y) . Since the iron group site is the remainder of the rare earth site and M, when the content of the rare earth site is v atomic% and the content of M is z atomic%, the content of the iron group site is expressed as (100-vz) atomic%.

Since the rare earth magnet of the present disclosure mainly contains binary elements of the rare earth element and the transition metal element, M is an ancillary component contained in a range that does not impair the effects of the rare earth magnet of the present disclosure. M will be described later.

The iron group site is the remainder of the rare earth site and M, and since M is an accessory component, the content of the iron group site is substantially controlled by the content v of the rare earth site. As the lower limit of the content v of the rare earth site is determined as described above, the α-Co phase, the α-Fe phase, and the α- (Co, Fe) phase are less likely to be formed, and as a result, the stability of the 1-5 phase is inhibited. There is no case. On the other hand, when the upper limit of the content v of the rare earth site is determined as described above, the transition metal elements (Co and Fe) for forming the 1-5 phases become difficult to be insufficient, and as a result, the stability of the 1-5 phases is inhibited. It doesn't work.

<M>

M is one or more types selected from the group consisting of transition metal elements other than Co and Fe, and Ga, Al, Zn, and In, and an unavoidable impurity element.

In M, transition metal elements other than Co and Fe, and Ga, Al, Zn, and In are elements which may contain in the range which does not impair the effect of this invention. In addition to these elements, M may contain an unavoidable impurity element. An unavoidable impurity element is an inevitable impurity element contained in the raw material of the rare earth magnet, or an impurity element that is mixed in the manufacturing process. Impurity element.

M (excluding unavoidable impurity elements) other than Mn (manganese), Ti (titanium), and Zr (zirconium) is present as a nonmagnetic phase at the interface of grains of the 1-5 phase, and the crystal grains of the 1-5 phase are magnetic. By dividing into pieces, the coercive force of the rare earth magnet is improved.

Ga, Al, Zn, and In and Cu among the transition metal elements lower the melting point of the grain boundary of the magnetic phase. Thereby, since a grain boundary becomes a liquid phase easily during temperature rising, sintering (including liquid phase sintering) temperature can be reduced.

Mn and Ti can be substituted with a part of Fe in 1-5 phase, and can further stabilize 1-5 phase.

Zr may be substituted with a part of the rare earth elements in the 1-5 phase to further stabilize the 1-5 phase.

If the value of the content z of M (including an unavoidable impurity element) is 8.0 atomic% or less, the content of rare earth sites and iron group sites is not excessively reduced. For this reason, if the value of z is 8.0 atomic% or less, the effect of the rare earth magnet of this indication will not be impaired. From this viewpoint, the value of z may be 7.0 atomic% or less, 5.0 atomic% or less, 3.0 atomic% or less, 1.0 atomic% or less, or 0.5 atomic% or less.

On the other hand, although the value of z may be 0 atoms, it is difficult to make no inevitable impurity element, or it causes a significant increase in manufacturing cost. In this respect, the value of z may be 0.1 atomic% or more, 0.2 atomic% or more, or 0.4 atomic% or more.

<relationship of x and y>

As described above, the overall composition of the rare-earth magnet of the present disclosure, formula _{(Ce x La (1-xw} ) R 'w) v indicated by _{(Co y Fe (1-y} )) (100-vz) M z . As described above, in the rare earth magnet of the present disclosure, even if a part of Co is substituted with Fe, 1 to 5 phases are stabilized by replacing part of Ce with La.

Stabilization of the 1-5 phase is achieved by i) determining the value of v in the range in which the 1-5 phase can be formed, and ii) having x and y in a predetermined relationship so that the 1-5 phase is stabilized. In addition, you may think that the value of w and z is small so that it does not affect the predetermined relationship of x and y mostly.

By creating a Formation Energy map of Ce-La-Fe-Co, the relationship between x and y when the 1-5 phases are stabilized can be obtained. The formation energy map calculates each formation energy when x and y of (Ce _x La _(1-x) ) (Co _y Fe _(1-y) ) ₅ are changed by the first principle calculation. For all formation energies of, it can be created using a normal solution approximation.

As a method of 1st principle calculation, the package (AkaiKKR) to which the Coherent Potential Approximation (CPA) of the Koringa-Kohn-Rostoker (KKR) method was applied is used. That is, each formation energy is calculated with respect to a total of 121 points when x and y of (Ce _x La _(1-x) ) (Co _y Fe _(1-y) ) ₅ are increased by 10%, respectively. do. And about 121 calculation results, formation energy map is created using a regular solution approximation formula. In addition, a regular solution approximation formula is as follows.

ΔE _RE5 (x, y) = E _RE5 (x, y)-( _{xyE CeCo5} + (1-x) yE _LaCe5 + (1-x) (1-y) E _LaFe5 + x (1-y) E _CeFe5 }

However, ΔE _RE5 (x, y) is the change in formation energy at x, y

E _RE5 (x, y) is the formation energy when x, y

E _{CeCo5 is,} the formation of the energy CeCo ₅

E _LaCe5 is, the formation of the energy LaCe ₅

E _{LaFe5 is} formed of ₅ energy LaFe

E _CeFe5 is, the formation of the energy CeFe ₅

In the formation energy map created in this way, 1-5 phases are stabilized in the area | region where formation energy is small. The boundary between the region where the 1-5 phase is stabilized and the region where the 1-5 phase becomes unstable has a relationship that y decreases as x increases, and the boundary is represented by y = -3x + 1.7. Moreover, the area | region where 1-5 phases are stabilized is an area | region where y is larger than the boundary. In this regard, the region where the 1-5 phase is stabilized is an region represented by y ≧ -3 × + 1.7.

In the region represented by y≥-3x + 1.7, the larger x and y, the smaller the formation energy. On the other hand, the region represented by y ≦ -1.25x + 1.25 is a region in which 1-5 phases are stabilized as Ce increases. As an area | region where 1-5 phases are stabilized, the area | region represented by y <= x + 1.00 may be sufficient.

In the region represented by y ≧ -3x + 1.7, since Ce and La coexist and Co and Fe coexist, it is necessary to satisfy 0 <x <1 and 0 <y <1.

In the region represented by y≥-3x + 1.7, since the formation energy becomes smaller as both x and y are larger, x may be 0.3 or more, 0.6 or more, or 0.7 or more, and y may be 0.1 or more and 0.2 or more. In the above, 0.3 or more may be sufficient. Although not limited by theory, in particular, when y is 0.3 or more, since the content of Fe decreases, the CeFe ₂ phase is less likely to be produced, and the improvement of saturation magnetization can be further stabilized. On the other hand, the smaller the formation energy, the more easily the 1-5 phases are stabilized. However, when the formation energy is somewhat small, the formation energy is stable enough for practical use. In this respect, x may be 0.9 or less, 0.85 or less, or 0.80 or less, and y may be 0.9 or less, 0.8 or less, or 0.7 or less.

6 shows the results of calculating the formation energy Er of various magnetic phases in the same manner. As can be seen from FIG. 6, the LaFe ₅ phase is unstable because the formation energy Er is positive. Further, formed on the energy Er CeFe ₅ is a section (負), but formed on the energy CeFe ₂ are, due to the low energy of formation than CeFe _5, it is preferentially formed in CeFe than ₂ different CeFe ₅ phase. 6 also shows that Ce and La need to coexist.

Moreover, the structural parameters (distance between Fe-Fe, distance between Fe-Co, etc.) based on the lattice constants of CeCo ₅ , LaCe ₅ , LaFe ₅ , and CeFe ₅ are calculated by the first principle calculation. The total magnetic moment map can be created by using the constant solution approximation equation for the structural parameter. Thereby, the relationship between formation energy and total magnetization moment can be examined. Since the formation energy is related to the stability of the 1-5 phase and the total magnetization moment is proportional to the magnetization, the relationship between the stability and the magnetization of the 1-5 phase can be examined from the formation energy map and the total magnetization moment map. In addition, as a method of 1st principle calculation, the result computed using the KKR-CPA (AkaiKKR) package was calculated using the Vienna ab initio simulation package (VASP) or Full potential local orbital minimum-base. It is supplemented by a calculation using code (FPLO).

In addition, from the total magnetization moment map, in order to prevent the fall of magnetization, it is understood that an area in which the content of La is not excessively small relative to the content of Ce is good, which is represented by y≤-1.25x + 1.25. to be. Although not bound by theory, it is thought that the reason is as follows. Ce has trivalent and tetravalent, and there are many tetravalent Ce among rare earth magnets. In comparison, La is only trivalent. In the tetravalent, the magnetization tends to disappear because 4f electrons are not localized, but La is trivalent and 4f electrons localize, so that magnetization is improved by La. From this point of view, when Ce and La coexist, increasing the La content is thought to improve magnetization. From this viewpoint, the area | region represented by y <= x + 1.00 is more preferable.

<< production method >>

The method for producing a rare earth magnet of the present disclosure includes a melt preparation step and a melt quenching step. Hereinafter, it demonstrates by these processes.

<Melting preparation process>

In the manufacturing method of this indication, the molten metal which has the composition similar to the whole composition of a rare earth magnet is prepared. The composition of the molten metal is made into the composition just before solidification end. When the molten metal component by evaporation etc. wears in the middle of molten metal holding | maintenance and / or coagulation | solidification, a raw material may be mix | blended and a molten metal may be prepared in consideration of the weight loss. In order to prevent oxidation of the molten metal and the like, it is preferable to prepare the molten metal in an inert gas atmosphere.

When it is not necessary to consider the abrasion of the melt component, the raw material so as to have a composition represented by the formula (Ce _x La _(1-xw) R ' _w ) _v (Co _y Fe _(1-y) ) _(100-vz) M _z To prepare a molten metal. In this equation, Ce, La, R ', Co, Fe, and M are the same as those described for the rare earth magnet. In addition, x, w, and y, and v and z are the same as the content demonstrated about the rare earth magnet. In this equation, similarly to the description of the rare earth magnet, the relationship of y≥-3x + 1.7 is satisfied. Moreover, you may satisfy | fill the relationship of y <= 1.25x + 1.25.

<Melt quenching process>

The molten metal having the composition described above is quenched at a speed of 1 × 10 ² to 1 × 10 ⁷ K / sec to obtain a thin ribbon. By doing in this way, a thin ribbon becomes the rare earth magnet of this indication. In thin ribbon, 1-5 phase exists and the ratio (molar ratio) of x, w, and y in 1-5 phase becomes substantially the same as x, w, and y at the time of molten metal. Although not bound by theory, the remaining balance during solidification, which does not become such a 1-5 phase, becomes a grain boundary phase and exists in the rare earth magnet. In other words, the rare-earth magnet of the present disclosure has 1-5 phases that satisfy 0 <x <1, 0 <y <1, and y≥-3x + 1.7, that is, (Ce _x La _(1-xw) R ' _w ) (Co _y Fe _(1-y) ) _t phase (but 0 ≦ w ≦ 0.1, 4 ≦ _t ≦ 6, preferably 4.5 ≦ _t ≦ 5.5). In the production method of the present disclosure, (Ce _x La _(1-xw) R ' _w ) (Co _y Fe _(1-y) ) _t phase (but 0≤w≤0.1, 4≤t≤6, preferably Sets x and y so that 4.5 ≦ t ≦ 5.5). Further, "0 <x <1, 0 < y <1, and y≥-3x + 1.7 which _{satisfies, (Ce x La (1-} xw) R 'w) (Co y Fe (1-y)) t The phase (but 0≤w≤0.1, 4≤t≤6, preferably 4.5≤t≤5.5) satisfies "0 <x <1, 0 <y <1, and y≥-3x + 1.7" _{to, (Ce x La (1-} xw) R 'w) is the same meaning as that of _{(Co y Fe (1-y} )) 5 a (but, 0≤w≤0.1) magnetic phase "containing.

As the quenching method, for example, the quenching device 10 as shown in FIG. 3 can be used to cool at a predetermined speed by the strip casting method. In the quench apparatus 10, raw materials are dissolved in the melting furnace 11, and a molten metal 12 having the above composition is prepared. The molten metal 12 is supplied to the tundish 13 at a constant supply amount. The molten metal 12 supplied to the tundish 13 is supplied to the cooling roll 14 by its own weight from the end part of the tundish 13.

The tundish 13 is made of a ceramic or the like, and temporarily melts the molten metal 12 continuously supplied from the melting furnace 11 at a predetermined flow rate, so that the molten metal 12 is cooled to the cooling roll 14. The flow can be rectified. In addition, the tundish 13 also has a function of adjusting the temperature of the molten metal 12 immediately before reaching the cooling roll 14.

The cooling roll 14 is formed of a material with high thermal conductivity, such as copper and chromium, and the surface of the cooling roll 14 is chromium-plated etc. in order to prevent erosion with high temperature molten metal. The cooling roll 14 can be rotated in the arrow direction at a predetermined rotational speed by the drive device not shown in the figure. By controlling this rotational speed, the cooling rate of a molten metal can be controlled by the speed of 1 * 10 <^2> -1 * 10 <^7> K / sec.

If the cooling rate of a molten metal is 1 * 10 <^2> K / sec or more, 1-5 phases are contained in thin ribbons. From this viewpoint, the cooling rate of the molten metal is more preferably 1 × 10 ³ K / sec or more. On the other hand, when the cooling rate of a molten metal is 1 * 10 <^7> K / sec or less, although the effect obtained by rapid cooling is saturated, there is little possibility of cooling a molten metal at a faster speed than necessary. The cooling rate of the molten metal may be 1 × 10 ⁶ K / sec or less, or 1 × 10 ⁵ K / sec or less.

In order to obtain the above-mentioned cooling rate, the temperature of the molten metal when supplied to the cooling roll 14 from the end of the tundish 13 may be 1300 ° C or more, 1350 ° C or more, or 1400 ° C or more, and 1600 ° C or less. 1550 degrees C or less, or 1500 degrees C or less is good. In addition, the circumferential speed of the cooling roll 14 may be 10 m / s or more, 14 m / s or more, or 18 m / s or more, and may be 30 m / s or less, 28 m / s or less, or 24 m / s or less. .

The molten metal 12 cooled and cooled on the outer circumference of the cooling roll 14 becomes a thin plate 15 and is peeled off from the cooling roll 14 to be recovered by a recovery apparatus. As needed, you may grind | pulverize thin ribbon 15 using a cutter mill etc., and may obtain powder. In the molten metal quenching step described so far, an inert gas atmosphere is preferable in order to prevent oxidation of the molten metal and the like.

Since the thin ribbon 15 has crystal grains and grain boundaries of 1-5 phases, only the thin ribbon 15 has a function as a permanent magnet. It is good also as a bond magnet or a sintering (including liquid phase sintering) magnet using the thin ribbon 15 or the pulverized powder of the thin ribbon 15.

EXAMPLE

Hereinafter, the rare earth magnet of the present disclosure and a manufacturing method thereof will be described in more detail with reference to Examples and Comparative Examples. In addition, the rare earth magnet of this indication and its manufacturing method are not limited to the conditions used by the following example.

<< preparation of the sample >>

A sample of the rare earth magnet was prepared in the following manner.

The molten metal of the composition shown in Table 1 was prepared using the arc melting method, and 1450 degreeC molten metal was supplied to the surface of the cooling roll rotating at 20 m / s circumference | rates using the strip casting method, and the ribbon was obtained. The cooling rate of the molten metal was 10 ⁶ K / s.

<< evaluation of the sample >>

The thin ribbon was roughly pulverized to obtain a powder, and the powder was analyzed by X-ray diffraction (XRD) to confirm the presence or absence of a 1-5 phase.

Further, the thin ribbon was roughly pulverized and resin molded, and the magnetization characteristics were measured using a 9T vibration sample magnetometer (VSM). The measurement was performed at normal temperature (20 degreeC). The saturated magnetization Ms and the anisotropic magnetic field Ha were calculated by the saturation asymptotic method.

The results are shown in Table 1. Reference Example 1 in Table 1 is described in JJZhang et al. Cited from JMMM 324 (2012) p.3272-3275. In addition, FIG. 1 shows the figure which recorded the result of Table 1 in the formation energy map, and FIG. 2 shows the figure which recorded the result of Table 1 in the total magnetic moment map. The formation energy map and the total magnetic moment map are created by the above-described method. In addition, the XRD analysis result about the sample of Examples 1-5 and Comparative Examples 1-4 is shown to FIG. 4 and FIG. 5, respectively. For the analysis of the respective samples of FIGS. 4 and 5, the upper side the XRD patterns of the samples shows the XRD pattern on the lower side is CeCo _5. 4 and 5, the horizontal axis is 2θ, and the vertical axis is X-ray intensity. In addition, the XRD analysis result about the sample of Examples 6-9 is shown in FIG. For the analysis of the samples of Figure 7, the upper side the XRD patterns of the samples shows the XRD pattern on the lower side is CeCo _5. In addition, the peak positions of the CeCo ₅ phase and the (Ce, La) (Co, Fe) ₅ phase are substantially the same.

As can be seen from Table 1 and FIGS. 4 to 5, in Examples 1 to 5, it was confirmed from the XRD analysis results that the peaks of phases 1-5 were clearly recognized. As can be seen from FIG. 1 and FIG. 2, it was confirmed that the correlation between the formed energy map and the total magnetic moment map created by the calculation and the results in Table 1 was found. In addition, in FIG. 1, y = -3x + 1.7 is a straight line which passes through the value of Example 1 and Example 2, and y = -x + 1.00 is a straight line which passes through Example 1 and Example 3. In FIG.

In addition, as can be seen from Table 1 and Fig. 7, in Examples 6 to 9, it was confirmed from the XRD analysis results that the peaks of phases 1-5 were clearly recognized. And from Table 1, it was confirmed that in the area of y≤-1.25x + 1.25, the saturation magnetization tends to be improved. In addition, when y was 0.3 or more, it was confirmed that the improvement of saturation magnetization was stabilized.

Although not bound by theory, it is thought that the reason why the improvement of saturation magnetization is stabilized in the region where y is 0.3 or more is as follows. 4 and 7, in Examples 1 to 9, even if 2θ is a position of 35 degrees, a peak is confirmed. This is considered to be because in Examples 1-9, some phases other than the 1-5 phase exist. And, when y is more than 0.3, it is considered that because of less content of Fe, other than the 1-5 phase, a low potential CeFe ₂ lowering the saturation magnetization.

From these results, the effect of the rare earth magnet of this indication and its manufacturing method was confirmed.

10 quenching device
11 melting furnace
12 molten metal
13 tundish
14 cooling rolls
15 beats

Claims (16)

Formula (Ce _x La _(1-xw) R ' _w ) _v (Co _y Fe _(1-y) ) _(100-vz) M _z (In the formula, R' is one or more rare earths other than Ce and La. Elemental,
M is a transition metal element other than Co and Fe, at least one selected from the group consisting of Ga, Al, Zn, and In, and an unavoidable impurity element,
0 <x <1.0,
0 <y <1.0,
0≤w≤0.1,
7.1≤v≤20.9, and
0≤z≤8.0)
Has the composition represented by
In the above formula, a rare earth magnet that satisfies the relationship of y≥-3x + 1.7. The method of claim 1,
In the above formula, a rare earth magnet that satisfies the relationship of y≤-1.25x + 1.25. The method according to claim 1 or 2,
Rare earth magnet wherein x satisfies 0.3≤x≤0.9. The method according to claim 1 or 2,
Rare earth magnet wherein x satisfies 0.6≤x≤0.9. The method according to claim 1 or 2,
The rare earth magnet wherein y satisfies 0.1 ≦ y ≦ 0.9. The method according to claim 1 or 2,
The rare earth magnet wherein y satisfies 0.1 ≦ y ≦ 0.7. The method according to claim 1 or 2,
The rare earth magnet wherein y satisfies 0.3 ≦ y ≦ 0.9. The method according to claim 1 or 2,
The rare earth magnet wherein y satisfies 0.3 ≦ y ≦ 0.7. Formula (Ce _x La _(1-xw) R ' _w ) _v (Co _y Fe _(1-y) ) _(100-vz) M _z (wherein R' is one or more rare earths other than Ce and La) Elemental,
M is a transition metal element other than Co and Fe, at least one selected from the group consisting of Ga, Al, Zn, and In, and an unavoidable impurity element,
0 <x <1.0,
0 <y <1.0,
0≤w≤0.1,
7.1≤v≤20.9, and
0≤z≤8.0)
Preparing a molten metal having a composition represented by and satisfying a relationship of y≥-3x + 1.7 in the above formula, and
A method for producing a rare earth magnet, comprising rapidly cooling the molten metal at a rate of 1 × 10 ² to 1 × 10 ⁷ K / sec to obtain a thin ribbon. The method of claim 9,
In said formula, the manufacturing method which satisfy | fills the relationship of y <= 1.25x + 1.25 further. The method according to claim 9 or 10,
The manufacturing method in which said x satisfies 0.3 <= x <= 0.9. The method according to claim 9 or 10,
The said manufacturing method in which x satisfy | fills 0.6 <= <= 0.9. The method according to claim 9 or 10,
The manufacturing method in which said y satisfies 0.1 <= y <= 0.9. The method according to claim 9 or 10,
The manufacturing method in which said y satisfies 0.1 <= y <= 0.7. The method according to claim 9 or 10,
The manufacturing method in which said y satisfies 0.3 <= y <= 0.9. The method according to claim 9 or 10,
Said y satisfies 0.3≤y≤0.7.

Images