JP2019040927A - Magnetic compound, method for manufacturing the same, and magnetic powder - Google Patents

Abstract

To provide a rare earth-iron based magnetic compound having ThMntype crystal structure, a method for manufacturing the same and magnetic powder which enable further improvement of an anisotropic magnetic field and saturation magnetization.SOLUTION: A magnetic compound, a method for manufacturing the same and a magnetic powder are disclosed. The magnetic compound has a composition represented by the formula (NdRZr)(FeCo)TMA(where R represents one or more rare earth elements other than Nd, T represents one or more elements selected from a group consisting of Ti, V, Mo and W, M represents an inevitable impurity element, etc. A represents one or more elements selected from a group consisting of N, C, H and P; and 0<x≤0.3, 0≤y≤0.1, 0≤z≤0.3, 7.7<a≤9.4, b=100-a-c-d, 3.1≤c<7.7, 0≤d≤1.0 and 1≤e≤18), has ThMntype crystal structure, and satisfies the relations given by the following expressions in the above formula: a≥1.6x+7.7; and c≥-14x+7.3.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a magnetic compound, a method for producing the same, and a magnetic powder. The present disclosure particularly relates to a magnetic compound, a manufacturing method thereof, and a magnetic powder having both a high anisotropic magnetic field and a high saturation magnetization.

  The application of permanent magnets covers a wide range of fields such as electronics, information communication, medical care, machine tool fields, industrial and automotive motors. In addition, there is an increasing demand for suppression of carbon dioxide emissions. In recent years, expectations for the development of permanent magnets with even higher characteristics have increased due to the spread of hybrid cars, energy saving in the industrial field, and improvement of power generation efficiency. .

  At present, Nd—Fe—B magnets, which are dominating the market as high-performance magnets, are also used in drive motor magnets for HV / EHV. Recently, new permanent magnet materials are being developed in response to the demand for further miniaturization and higher output of motors (increase in residual magnetization of magnets).

As one of the development of materials having performance exceeding that of Nd—Fe—B based magnets, research on rare earth-iron based magnetic compounds having a ThMn ₁₂ type crystal structure is underway.

For example, Patent Document 1 discloses that the formula (R _(1-x) Zr _x ) _a (Fe _(1-y) Co _y ) _b T _{cM d} A _e (R is one or more rare earth elements, and T Is one or more elements selected from the group consisting of Ti, V, Mo and W, and M is one or more elements selected from the group consisting of inevitable impurity elements and Al, Cr, Cu, Ga, Ag and Au. A is one or more elements selected from the group consisting of N, C, H and P, and 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.6, 4 ≦ a ≦ 20, b = 100-acd, 0 <c <7, 0 ≦ d ≦ 1, and 1 ≦ e ≦ 18), and a magnetic material having a ThMn ₁₂ type crystal structure Compounds are disclosed.

Japanese Patent Laid-Open No. 2006-58707

In the magnetic compound disclosed in Patent Document 1, the content of the α-Fe phase is not sufficiently reduced, and there is a limit to further improvement of the anisotropic magnetic field and saturation magnetization. Accordingly, the present inventors have found that a rare earth-iron-based magnetic compound having a ThMn ₁₂ type crystal structure is desired to further improve the anisotropic magnetic field and saturation magnetization.

The present disclosure has been made in order to solve the above-described problems. A rare earth-iron-based magnetic compound having a ThMn ₁₂ type crystal structure, an anisotropic magnetic field and a saturation magnetization are further improved, a method for producing the same, and magnetism The purpose is to provide powder.

In order to achieve the above object, the present inventors have made extensive studies and completed the magnetic compound of the present disclosure, a method for producing the same, and a magnetic powder. The summary is as follows.
<1> formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d A e
(In the above formula, R is one or more rare earth elements other than Nd,
T is one or more elements selected from the group consisting of Ti, V, Mo and W,
M is an inevitable impurity element and one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au,
A is one or more elements selected from the group consisting of N, C, H and P, and
0 <x ≦ 0.3,
0 ≦ y ≦ 0.1,
0 ≦ z ≦ 0.3,
7.7 <a ≦ 9.4,
b = 100-acd,
3.1 ≦ c <7.7,
0 ≦ d ≦ 1.0, and
1 ≦ e ≦ 18)
Having a composition represented by
In the above formula, the relationship of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 is satisfied, and
It has a ThMn ₁₂ type crystal structure,
Magnetic compound.
<2> The magnetic compound according to <1>, wherein 3.1 ≦ c ≦ 7.3.
<3> The magnetic compound according to <1> or <2>, wherein 7.7 <a ≦ 8.7 in the formula.
<4> formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d
(In the above formula, R is one or more rare earth elements other than Nd,
T is one or more elements selected from the group consisting of Ti, V, Mo and W,
M is an inevitable impurity element and one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au, and
0 <x ≦ 0.3,
0 ≦ y ≦ 0.1,
0 ≦ z ≦ 0.3,
7.7 <a ≦ 9.4,
b = 100-acd,
3.1 ≦ <c <7.7, and
(0 ≦ d ≦ 1.0)
And having a composition represented by:
Preparing a molten metal satisfying the relationship of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 in the formula,
Quenching the molten metal at a rate of 1 × 10 ² to 1 × 10 ⁷ K / sec to obtain flakes; and
Intruding A (one or more elements selected from the group consisting of N, C, H and B) into the flakes;
The manufacturing method of the magnetic compound as described in <1> containing.
<5> The method according to <4>, further comprising grinding the flakes before the intrusion to obtain a powder.
<6> The method according to <5>, further comprising heat-treating the flakes at 800 to 1300 ° C. for 2 to 120 hours.
<7> The method according to <5> or <6>, further comprising heat-treating the powder at 800 to 1300 ° C. for 2 to 120 hours.
<8> The method according to any one of <4> to <7>, wherein 3.1 ≦ c ≦ 7.3.
<9> The method according to any one of <4> to <8>, wherein 7.7 <a ≦ 8.7 in the formula.
<10> formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d A e
(In the above formula, R is one or more rare earth elements other than Nd,
T is one or more elements selected from the group consisting of Ti, V, Mo and W,
M is an inevitable impurity element and one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au,
A is one or more elements selected from the group consisting of N, C, H and P, and
0 <x ≦ 0.3,
0 ≦ y ≦ 0.1,
0 ≦ z ≦ 0.3,
7.7 <a ≦ 9.4,
b = 100-acd,
3.1 ≦ c <7.7,
0 ≦ d ≦ 1.0, and
1 ≦ e ≦ 18)
Having a composition represented by
In the above formula, the relationship of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 is satisfied, and
It has a ThMn ₁₂ type crystal structure,
Magnetic powder.

  According to the present disclosure, the content of the α-Fe phase in the magnetic compound can be minimized by specifying the overall composition of the magnetic compound in consideration of the component composition in the magnetic phase. And according to this indication, coupled with the effect of nitriding, it is possible to provide a magnetic compound in which both the anisotropic magnetic field and the saturation magnetization are further improved, its manufacturing method, and magnetic powder.

FIG. 1 shows that the Zr content ratio x, the rare earth site content a, and the Ti content c for the entire compositions of Examples 1 to 7 and Comparative Examples 1 to 8 are shown in Table 1. It is a graph summarizing the relationship. FIG. 2 is a ternary phase diagram of Nd—Fe—Ti. Figure 3 is a graph showing the stable region of the T component of R'Fe _{12-v T} v compound. FIG. 4 is a schematic view of an apparatus used in the strip casting method. FIG. 5 is a view showing an SEM image of the sample of Comparative Example 5. FIG. 6 is a graph summarizing the relationship between the content ratio x ′ of Zr and the content p of rare earth sites for the compositions of the magnetic phases of Examples 1 to 7 and Comparative Examples 1 to 8 from Table 4.

  Hereinafter, embodiments of the magnetic compound, the manufacturing method thereof, and the magnetic powder of the present disclosure will be described in detail. In addition, embodiment shown below does not limit the magnetic compound of this indication, its manufacturing method, and a magnetic powder.

The magnetic compound of the present disclosure has a ThMn ₁₂ type crystal structure. Since the magnetic compound of the present disclosure contains Nd, Fe, and Ti as main elements, a composition that facilitates stabilization of the ThMn ₁₂ type crystal structure will be described using a ternary system of Nd—Fe—Ti.

FIG. 2 shows a ternary phase diagram of Nd—Fe—Ti (Source: A. Margarian, et al., Journal of Applied Physics 76, 6153 (1994)). As can be seen from FIG. 2, in the ternary system of Nd—Fe—Ti, there are NdFe _12-w Ti _w phase, Nd ₃ Fe _29-w Ti _w phase, and Nd ₂ Fe _17-w Ti _w phase. obtain. These phases are represented in FIG. 2 by “1:12”, “3:29”, and “2:17”, respectively. Among these phases, the NdFe _12-w Ti _w phase has a ThMn ₁₂ type crystal structure. Examples of the NdFe _12-w Ti _w phase include an NdFe ₁₁ Ti phase. Hereinafter, the NdFe _12-w Ti _w phase, the Nd ₃ Fe _29-w Ti _w phase, and the Nd ₂ Fe _17-w Ti _w phase are respectively referred to as a 1-12 phase, a 3-29 phase, and a 2-17 phase. Sometimes expressed as a phase.

  In these phases, the content ratio (molar ratio) of Nd when the Fe and Ti contents are set to 1 is 0.083 for the 1-12 phase, the 3-29 phase, and the 2-17 phase, respectively. 0.103 and 0.118. That is, the 3-29 phase and the 2-17 phase have a higher Nd content ratio than the 1-12 phase.

  As can be seen from FIG. 2, in the ternary system of Nd—Fe—Ti, an α-Fe phase can also exist in addition to the 1-12 phase, the 3-29 phase, and the 2-17 phase. When the Nd content is 7.7 atomic%, the stability of the 1-12 phase is most easily achieved, and the content of the α-Fe phase is likely to decrease. When the Nd content is less than 7.7 atomic%, the 3-19 phase, the 2-17 phase, and the like are unlikely to exist, and the α-Fe phase content is likely to increase. On the other hand, when the content of Nd is more than 7.7 atomic%, the content of the 3-29 phase, the 2-17 phase, etc. is likely to increase, and the content of the α-Fe phase is likely to decrease. “3-29 phase, 2-17 phase, etc.” means a generic term for phases having a higher Nd content than the 1-12 phase. As such a phase, in addition to the 3-29 phase and the 2-17 phase, for example, a phase in which a part of Nd is missing in the 3-29 phase and the 2-17 phase, and the 3-29 phase In addition, a phase in which a smaller number of Nd atoms have intruded into the 2-17 phase can be exemplified.

  As shown in FIG. 2, the composition region in which the 1-12 phase stably exists is very narrow. For this reason, if the Nd content is reduced in the entire magnetic compound, the 1-12 phase is not stabilized, and the content of the α-Fe phase tends to increase. On the other hand, when the content of Nd is increased, the 1-12 phase is not stabilized, and the contents of the 3-29 phase, the 2-17 phase and the like are likely to increase.

  In order to stabilize the 1-12 phase, Zr is conventionally added to the ternary system of Nd—Fe—Ti. However, with regard to the Zr content, in order to prevent the effects of Nd from being inhibited, the Zr content ratio (molar ratio) is only considered to be higher than the Nd content ratio (molar ratio). It wasn't. Therefore, for example, in the magnetic compound disclosed in Patent Document 1, the content of the α-Fe phase cannot be sufficiently reduced.

  A magnetic compound has a magnetic phase and a grain boundary phase. The grain boundary phase is complicated by various phases. In addition, the magnetic properties of magnetic compounds are often derived from the magnetic phase. Therefore, first, the content ratio of Zr in the magnetic phase was investigated.

  Without being bound by theory, it is believed that most of Zr in the magnetic compound is substituted for a part of Nd. Therefore, the relationship between the content ratio (molar ratio) x ′ of Zr when the total content of Nd and Zr in the magnetic phase is 1, and the total content (atomic%) p of Nd and Zr with respect to the entire magnetic phase. investigated.

  As a result, the present inventors have found the following.

The numerical values in the magnetic phase, x ′ and p, are in a linear relationship (proportional relationship), and the slope thereof is positive. From this, it can be said that when the Zr ratio x ′ in the magnetic phase is increased, the content p of the rare earth site represented by Nd _(1-xy) R _y Zr _x in the magnetic phase increases.

Further, x ′ in the magnetic phase and x in the overall composition are substantially equal. From this, the content ratio (molar ratio) of Zr, where the total content of Nd and Zr in the overall composition is 1, is x, and the total content (atomic%) of Nd and Zr in the overall composition is a. , Investigated the relationship. As a result, as in the case of the magnetic phase, when the Zr ratio x in the overall composition is increased, the content a of the rare earth site represented by Nd _(1-xy) R _y Zr _x in the overall composition is increased. It turned out to increase.

  Furthermore, in the relationship between x and a, it was found that when a <1.6x + 7.7, the magnetic phase is not stable and many α-Fe phases exist in the grain boundary phase. This is a state diagram of the ternary system of Nd—Fe—Ti (not containing Zr) shown in FIG. 2 and corresponds to the fact that the content of α-Fe phase tends to increase when the content of Nd is small. To do.

  On the other hand, when a ≧ 1.6x + 7.7, the content of the α-Fe phase existing in the grain boundary phase is reduced. Moreover, it turned out that a small amount of 3-29 phase, 2-17 phase, etc. exist in a grain boundary phase. This is a phase diagram of the ternary system of Nd—Fe—Ti (not containing Zr) shown in FIG. 2. When the content of Nd is large, the content of the α-Fe phase tends to decrease. This corresponds to the 29 phase and the 2-17 phase easily existing.

  Until now, in order to stabilize the 1-12 phase, the knowledge when adding Zr to the ternary system of Nd—Fe—Ti has been described. The knowledge obtained by examining the Ti content in order to further stabilize the 1-12 phase will now be described.

  A magnetic compound has a magnetic phase and a grain boundary phase. The grain boundary phase is complicated by various phases. In addition, the magnetic properties of magnetic compounds are often derived from the magnetic phase. Therefore, first, the content ratio of Zr in the magnetic phase was investigated.

  Therefore, the relationship between the Zr content ratio (molar ratio) x ′ when the total content of Nd and Zr in the magnetic phase is 1 and the Ti content (atomic%) q with respect to the entire magnetic phase was investigated.

  As a result, the present inventors have found the following.

X ′ in the magnetic phase and x in the overall composition are approximately equal. From this, it is assumed that the content ratio (molar ratio) of Zr when the total content of Nd and Zr in the overall composition is 1, and the content (atomic%) of Ti in the overall composition is c, and the relationship. investigated. As a result, it was found that the content c of the rare earth site represented by Nd _(1-xy) R _y Zr _x in the overall composition changes with the change in the Zr ratio x in the overall composition.

  Furthermore, in the relationship between x and c, it was found that when c <−14x + 7.3, the magnetic phase was not stable and many α-Fe phases existed in the grain boundary phase. This is a state diagram of the ternary system of Nd—Fe—Ti (not containing Zr) shown in FIG. 2 and corresponds to the fact that the content of α-Fe phase tends to increase when the content of Nd is small. To do.

  On the other hand, when c ≧ −14x + 7.3, the content of the α-Fe phase existing in the grain boundary phase is reduced. Moreover, it turned out that a small amount of 3-29 phase, 2-17 phase, etc. exist in a grain boundary phase. This is a phase diagram of the ternary system of Nd—Fe—Ti (not containing Zr) shown in FIG. 2. When the content of Nd is large, the content of the α-Fe phase tends to decrease. This corresponds to the 29 phase and the 2-17 phase easily existing.

  The constituents of the magnetic compound of the present disclosure, the manufacturing method thereof, and the magnetic powder, which have been completed based on the knowledge described so far, will be described below.

《Magnetic compound》
Magnetic compounds of the present disclosure, having a composition represented by the formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d A e. This formula represents the overall composition of the magnetic compound of the present disclosure.

  In the above formula, Nd is neodymium, R is one or more rare earth elements other than Nd, Zr is zirconium, Fe is iron, and Co is cobalt. T is one or more elements selected from the group consisting of Ti, V, Mo and W. Ti represents titanium, V represents vanadium, Mo represents molybdenum, and W represents tungsten. M is an inevitable impurity element and at least one element selected from the group consisting of Al, Cr, Cu, Ga, Ag, and Au. Al is aluminum, Cr is chromium, Cu is copper, Ga is gallium, Ag is silver, and Au is gold. A is one or more elements selected from the group consisting of N, C, H and P. N represents nitrogen, C represents carbon, H represents hydrogen, and P represents phosphorus.

x and y are content ratios (molar ratios) of Zr and R, respectively, where the entire rare earth site represented by Nd _(1-xy) R _y Zr _x is 1. At the rare earth site, Nd is the balance of R and Zr.

z is the content ratio (molar ratio) of Co when the entire iron group site represented by Fe _(1-z) Co _z is 1. At the iron group site, Fe is the balance of Co.

a, b, c, and d, respectively, of the magnetic compound of the present _{disclosure, (Nd (1-x-} y) R y Zr x) a (Fe (1-z) Co z) b T c M d The content (atomic%) of rare earth sites, iron group sites, T, and M, when the entire magnetic compound precursor represented by formula (1) is 100 atomic%. In the above formula, since b = 100-acd, the iron group sites are the remainder of rare earth sites, T, and M in the entire magnetic compound precursor. _Then, A is an element that is entering the magnetic compound precursor represented by _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d is there. e is the content (atomic%) of A with respect to the whole magnetic compound precursor. Therefore, a + b + c + d + e exceeds 100 atomic%.

  Next, the constituent elements of the above formula will be described.

<Nd>
Nd is a rare earth element and is an essential component for the magnetic compound of the present disclosure because it exhibits permanent magnet characteristics.

<R>
R is one or more rare earth elements other than Nd. In the present specification, unless otherwise specified, the rare earth elements are Y, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

The magnetic compound of the present disclosure specifies the rare earth element in the magnetic compound as Nd, specifies the content of Nd, and minimizes the content of the α-Fe phase in the magnetic compound. It is difficult to eliminate the rare earth element R other than Nd from the Nd raw material. However, if the value of y is 0 to 0.1 at a rare earth site represented by Nd _(1-xy) R _y Zr _x , the characteristics of the magnetic compound of the present disclosure are as follows. And may be considered substantially equivalent.

  The value of y is ideally 0, but excessively increasing the purity of the raw material of Nd leads to an increase in manufacturing cost, so the value of y is 0.01 or more, 0.02 or more, It may be 0.03 or more, 0.04 or more, or 0.05 or more. On the other hand, since the value of y is preferably low as long as the purity of the raw material of Nd does not increase excessively, the value of y is 0.09 or less, 0.08 or less, 0.07 or less, or 0.06 or less. It may be.

<Zr>
A part of Nd and / or R is substituted with Zr, and contributes to the stability of the ThMn ₁₂ type crystal structure. Substitution of Nd and / or R in the ThMn type ₁₂ crystal with Zr causes crystal lattice shrinkage. Thereby, even when the magnetic compound is heated to a high temperature (600 ° C. or higher) or nitrogen atoms are allowed to enter the crystal lattice, the ThMn ₁₂ type crystal structure is easily maintained. On the other hand, in terms of magnetic characteristics, strong magnetic anisotropy derived from Nd is weakened by replacing a part of Nd with Zr. Therefore, the Zr content is determined from both the stability and magnetic properties of the ThMn ₁₂ type crystal structure.

Zr is essential for stabilizing the ThMn ₁₂ type crystal structure and suppressing decomposition of the magnetic compound at high temperatures. Even if Zr is a small amount, its effect is recognized. Therefore, the value of x should be greater than 0 at the rare earth site represented by Nd _(1-xy) R _y Zr _x . From the viewpoint of clearly enjoying the effect of Zr, the value of x may be 0.02 or more, 0.04 or more, 0.06 or more, or 0.08 or more. On the other hand, if the value of x is 0.3 or less, the anisotropic magnetic field will not be significantly reduced. Moreover, it is difficult to produce an Fe ₂ Zr phase. When the magnetic compound is nitrided, the Fe ₂ Zr phase inhibits the expression of the coercive force. If the Fe ₂ Zr phase is difficult to generate, the expression of the coercive force is difficult to be inhibited. From these viewpoints, the value of x may be 0.28 or less, 0.26 or less, 0.24 or less, or 0.22 or less.

The total content of Nd, R, and Zr that has been described so far is represented by the content a of rare earth sites represented by Nd _(1-xy) R _y Zr _x . If the content a of the rare earth site exceeds 7.7 atomic%, the ThMn ₁₂ type crystal structure will be decomposed even if the magnetic compound is heated to a high temperature (600 ° C. or higher) or nitrogen atoms enter the crystal lattice. It becomes difficult. When the ThMn ₁₂ type crystal structure is decomposed, the content of the α-Fe phase increases. Therefore, if the ThMn ₁₂ type crystal structure is difficult to be decomposed, the content of the α-Fe phase is difficult to increase. In this respect, the rare earth site content a is preferably 7.8 atomic% or more, more preferably 7.9 atomic% or more, and even more preferably 8.0 atomic%. On the other hand, if the content a of the rare earth site is 9.4 atomic% or less, the magnetic anisotropy of the magnetic compound is unlikely to decrease. This is because when a large amount of Nd is substituted with Zr, a large amount of phases other than the magnetic phase are generated, and the strong magnetic anisotropy derived from Nd is remarkably reduced. From the viewpoint of suppressing a decrease in magnetic anisotropy, the content a of rare earth sites is preferably 9.2 atomic% or less, more preferably 8.7 atomic% or less, and even more preferably 8.5 atomic% or less. .

  Furthermore, as described above, in the overall composition of the magnetic compound, when the Zr content ratio x at the rare earth site and the rare earth site content a satisfy the relationship of a ≧ 1.6x + 7.7, the α-Fe phase The content of can be 2% by volume or less with respect to the entire magnetic compound. In addition, both the saturation magnetization and the anisotropic magnetic field of the magnetic compound after nitriding can be improved.

  In the present specification, the content of the α-Fe phase is represented by volume% measured in the following manner. The magnetic compound is resin-filled and polished, and is observed at a plurality of locations using an optical microscope or SEM-EDX, and the average area ratio of the α-Fe phase on the observation surface is measured by image analysis. An average area ratio means the average of the area ratio measured in each observation location.

  Assuming that the structure in the magnetic compound is not oriented in a specific direction, a relationship of S≈V is established between the average area ratio S and the volume ratio V. From this, regarding the content of the α-Fe phase, the value of the average area ratio (area%) of the α-Fe phase measured in the manner described above is defined as the content (volume%) of the α-Fe phase. .

<T>
T is one or more elements selected from the group consisting of Ti, V, Mo and W. Ti, V, Mo, and W may each be considered to have the same effect. 3, R'Fe _{12-v T} v compound (R 'is a rare earth element.) Is a diagram showing the stabilization region of T in (Source:... K.H.J Buschow, Rep Prog Phys 54, 1123 (1991)). By adding Ti, V, Mo, and W as the third element to the R′—Fe binary system, the ThMn ₁₂ type crystal structure becomes stable and exhibits excellent magnetic properties. Known by.

Conventionally, in order to obtain the stabilization effect of the T component, a ThMn ₁₂ type crystal structure has been formed by adding T in a larger amount than necessary. Therefore, the content rate of the Fe component constituting the magnetic compound is lowered, and the occupied site of Fe atoms that most affects the magnetization is replaced with, for example, T atoms, and the entire magnetization is lowered. Moreover, when the content of T increases, Fe ₂ T is easily generated.

When the content c of T is less than 7.7 atomic%, the magnetization is difficult to decrease and Fe ₂ Ti is difficult to be generated. From these viewpoints, the content c of T is preferably 7.5 atomic percent or less, more preferably 7.3 atomic percent or less, and even more preferably 7.0 atomic percent or less.

On the other hand, when the content c of T is 3.1 atomic% or more, the ThMn ₁₂ type crystal structure is easily stabilized. From this viewpoint, it is preferably 3.5 atomic percent or more, more preferably 4.0 atomic percent or more, and even more preferably 5.0 atomic percent or more.

  Furthermore, as described above, when the Zr content ratio x at the rare earth site and the T content c satisfy the relationship of c ≧ −14x + 7.3 in the overall composition of the magnetic compound, the α-Fe phase is contained. The amount can be 2% by volume or less based on the entire magnetic compound. In addition, both the saturation magnetization and the anisotropic magnetic field of the magnetic compound after nitriding can be improved.

<M>
M is an inevitable impurity element and at least one element selected from the group consisting of Al, Cr, Cu, Ga, Ag, and Au. Inevitable impurities mean that impurities contained in the raw materials of magnetic compounds or impurities mixed in during the manufacturing process cannot be avoided. Impurities that lead to Inevitable impurity elements include Si and Mn.

M (excluding incidental impurity elements), the viscosity of the suppression of grain growth of the _12-inch ThMn crystal, or a phase other than the phase with the crystal structure of _12-inch ThMn (e.g., the grain boundary phase), which contributes to the melting point However, it is not essential in the magnetic compound of the present disclosure.

  The content d of M is 1.0 atomic% or less. When the M content d is 1.0 atomic% or less, the content of the Fe component constituting the magnetic compound is lowered, and as a result, the entire magnetization is unlikely to decrease. From this viewpoint, the M content d is preferably 0.8 atomic percent or less, more preferably 0.6 atomic percent or less, and even more preferably 0.4 atomic percent or less.

  On the other hand, from the viewpoint of clearly enjoying the effect of M (excluding inevitable impurity elements), the content of M is preferably 0.1 atomic% or more, more preferably 0.2 atomic% or more, and 3 atomic% or more is even more preferable. Further, when not containing one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au, M is the content of unavoidable impurities. The content of unavoidable impurities is preferably as low as possible. However, excessively reducing the content of unavoidable impurities causes an increase in production cost and the like, so that the magnetic properties of the magnetic compound are not substantially affected. In the range, a small amount of inevitable impurities may be contained. From this viewpoint, the lower limit of the M content d may be 0.05 atomic%, 0.1 atomic%, or 0.2 atomic%.

<Fe and Co>
The magnetic compound of the present disclosure uses Fe other than the above elements, but a part of Fe may be substituted with Co. When a part of Fe is substituted with Co, a part of Fe in the α-Fe phase is substituted with Co. In this specification, when expressed as an α-Fe phase, unless otherwise specified, the α-Fe phase includes a phase in which a part of Fe in the α-Fe phase is substituted with Co.

  By replacing a part of Fe with Co, spontaneous magnetization increases due to the Slater poling rule, and both the anisotropic magnetic field and saturation magnetization characteristics are improved. In addition, since a part of Fe is substituted with Co, the Curie point of the magnetic compound is increased, which has an effect of suppressing a decrease in magnetization at a high temperature.

In order to enjoy these effects clearly, the Co content ratio (molar ratio) z when the entire iron group site represented by Fe _(1-z) Co _z is 1 is 0.05 or more. Preferably, 0.10 or higher is preferable, and 0.15 or higher is even more preferable.

On the other hand, even if the Co content is excessive, it is difficult to obtain the effect of the Slater poling law. If the Co content ratio (molar ratio) z is 0.30 or less, the effect of the slater poling rule is difficult to weaken. From this viewpoint, the Co content ratio (molar ratio) z is preferably 0.26 or less, more preferably 0.24 or less, and still more preferably 0.20 or less.
(A)
A is one or more elements selected from the group consisting of N, C, H and P. A can is enlarged grating ThMn ₁₂ phase by entering between crystal lattice of ThMn ₁₂ phase, the anisotropic magnetic field to improve the both characteristics of the saturation magnetization. The content e of M is 1 atomic% or more and 18 atomic% or less. When the content e of M is 1 atomic% or more, the lattice of the ThMn ₁₂ phase can be expanded. From the viewpoint of expanding the lattice of the ThMn ₁₂ phase, the M content e is preferably 5 atomic% or more, more preferably 7 atomic% or more, and even more preferably 8 atomic% or more. If the content e of M is 18 atomic% or less, the content of the Fe component constituting the magnetic compound will not be excessively lowered. If there is no excessive decrease in the content of the Fe component, the stability of the ThMn ₁₂ phase is impaired, a part of the magnetic compound is decomposed, and the magnetization does not decrease. From the viewpoint of suppressing the decrease in magnetization, the M content e is preferably 14 atomic percent or less, more preferably 12 atomic percent or less, and even more preferably 10 atomic percent or less.

<Crystal structure>
The magnetic compound of the present disclosure has a ThMn ₁₂ type crystal structure. The crystal structure of the ThMn ₁₂ type is tetragonal. The ThMn ₁₂ type crystal structure shows the strongest X-ray diffraction intensity when 2θ is 42.36 ° ((321) plane) by X-ray diffraction (XRD) of a Cu source. Further, when 2θ is 33 ° ((310) plane), weak X-ray diffraction intensity is exhibited.

In the ThMn ₁₂ type crystal structure, the X-ray diffraction intensity at 2θ is 42.36 ° ((321) plane) and the X-ray diffraction intensity at I _c (321) and 2θ is 33 ° ((310) plane). I _c (310) is represented by I _c (310), and I _c (321) is 100, I _c (310) is 13.2.

It is known that when the ThMn ₁₂ type crystal structure collapses (disorders), it changes to a Th ₃ Mn ₂₉ type crystal structure. The Th ₃ Mn ₂₉ type crystal structure shows the strongest X-ray diffraction intensity when 2θ is 42.35 ° ((−133) plane) by X-ray diffraction (XRD) of a Cu source. Further, when 2θ is 33 ° ((302) plane), it shows weak X-ray diffraction intensity.

In the Th ₃ Mn ₂₉ type crystal structure, the X-ray diffraction intensity at 2θ of 42.35 ° ((−133) plane) is expressed as I _c (−133) and X at 2θ of 33 ° ((302) plane). When the line diffraction intensity is represented by I _c (302) and I _c (-133) is 100, I _c (302) is 5.9.

From this, the ThMn ₁₂ type crystallinity indicating the proportion of the ThMn ₁₂ type crystal structure in the magnetic compound is {I _m (310) −I _c (302)} / {I _c (310) −I _c (302)}. Here, I _m (310) is a measured value of X-ray diffraction intensity on the (310) plane of the magnetic compound. If the crystal structure is a complete ThMn ₁₂ type, the ThMn ₁₂ type crystallinity is 100%, and if the crystal structure is a complete Th ₃ Mn ₂₉ type, the ThMn ₁₂ type crystallinity is 0%.

In the magnetic compound of the present disclosure, the ThMn ₁₂ type crystal structure preferably occupies 50% or more, that is, the ThMn ₁₂ type crystallinity is preferably 50% or more. If the ThMn ₁₂ crystallinity is 50% or more, the ThMn ₁₂ crystal structure is stable in the magnetic compound, and the α-Fe phase hardly increases. From the viewpoint of stability of the ThMn ₁₂ type crystal structure, the ThMn ₁₂ type crystallinity is preferably as high as possible, and is preferably 60% or more, 70% or more, 80% or more, or 90% or more. On the other hand, the ThMn type ₁₂ crystallinity need not be 100%, but may be 98% or less, 96% or less, 94% or less, or 92% or less.

  As described so far, according to the magnetic compound of the present disclosure, the content of the α-Fe phase in the magnetic compound is minimized, and after nitriding, both the saturation magnetization and the anisotropic magnetic field are further improved. be able to.

  The magnetic compound of the present invention may be used as a raw material for sintered magnets and bonded magnets, or may be used as a magnetic powder as it is.

<Magnetic powder>
When used as a magnetic powder, the magnetic powder is
Formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d A e
(In the above formula, R is one or more rare earth elements other than Nd,
T is one or more elements selected from the group consisting of Ti, V, Mo and W,
M is an inevitable impurity element and one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au,
A is one or more elements selected from the group consisting of N, C, H and P, and
0 <x ≦ 0.3,
0 ≦ y ≦ 0.1,
0 ≦ z ≦ 0.3,
7.7 <a ≦ 9.4,
b = 100-acd,
3.1 ≦ c <7.7,
0 ≦ d ≦ 1.0, and
1 ≦ e ≦ 18)
Having a composition represented by
In the above formula, the relationship of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 is satisfied, and
It has a ThMn ₁₂ type crystal structure.

"Production method"
The manufacturing method of the magnetic compound of this indication contains a molten metal preparation process, a molten metal quenching process, and A element penetration | invasion process. Hereinafter, each step will be described.

<Melten preparation process>
In the magnetic compound of the present disclosure, the overall composition of the magnetic compound before nitriding and the composition of the melt prepared when the magnetic compound is manufactured are substantially the same. As for the composition of the molten metal, it is not considered that the molten metal component is depleted due to evaporation or the like during the molten metal holding and / or solidification. When the molten metal component is depleted due to manufacturing conditions, raw materials may be blended in consideration of the depleted amount.

If the melt depletion does not need to be considered, the molten metal having a composition represented by the formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d prepare. In the above formula, Nd, R, Zr, Fe, Co, T, and M are the same as those described for the magnetic compound. Moreover, x, y, and z, and a, b, c, and d are the same as the content demonstrated with the magnetic compound. In the above formula, the relations of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 are satisfied.

<Melting quenching process>
The molten metal having the above composition is rapidly cooled at a rate of 1 × 10 ² to 1 × 10 ⁷ K / sec. The rapid cooling stabilizes the ThMn ₁₂ type crystal structure and makes it easy to minimize the content of the α-Fe phase.

  As the rapid cooling method, for example, a rapid cooling device 10 as shown in FIG. 4 can be used, and cooling can be performed at a predetermined speed by a strip casting method. In the rapid cooling apparatus 10, the raw material is melted 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 from the end of the tundish 13 to the cooling roll 14 by its own weight.

  The tundish 13 is made of ceramics or the like, can temporarily store the molten metal 12 continuously supplied from the melting furnace 11 at a predetermined flow rate, and can rectify the flow of the molten metal 12 to the cooling roll 14. 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 made of a material having high thermal conductivity such as copper or chromium, and the surface of the cooling roll 14 is subjected to chromium plating or the like in order to prevent erosion with a high-temperature molten metal. The cooling roll 14 can be rotated in the direction of the arrow at a predetermined rotation speed by a driving device (not shown). By controlling this rotational speed, the cooling rate of the molten metal can be controlled to a speed of 1 × 10 ² to 1 × 10 ⁷ K / sec.

If the cooling rate of the molten metal is 1 × 10 ² K / sec or more, the ThMn ₁₂ type crystal structure can be stabilized and the content of the α-Fe phase can be easily minimized. In this respect, the cooling rate of the molten metal is more preferably 1 × 10 ³ K / sec or more. On the other hand, if the cooling rate of the molten metal is 1 × 10 ⁷ K / sec or less, there is little possibility that the molten metal is cooled at a faster rate than necessary even though the effect obtained by rapid cooling is saturated. The cooling rate of the molten metal may be 1 × 10 ⁶ K / sec or less or 1 × 10 ⁵ K / sec or less.

  The molten metal 12 cooled and solidified on the outer periphery of the cooling roll 14 becomes a thin piece 15 which is peeled off from the cooling roll 14 and recovered by a recovery device. If necessary, the flakes 15 may be pulverized using a cutter mill or the like to obtain a powder.

<A element penetration process>
The element A is invaded into the thin piece 15. The element A is at least one selected from the group consisting of N, C, H and P. In view of the ease of penetration of the A element, the penetration of the A element is preferably performed after the flakes 15 are crushed.

  When the A element is nitrogen, for example, nitrogen gas or a mixed gas of nitrogen gas and hydrogen gas, ammonia gas, or a mixed gas of ammonia gas and hydrogen gas is used as the nitrogen source. In use, the flakes 15 are heated and nitrided at 200-600 ° C. for 1-24 hours.

When the element A is carbon, for example, C ₂ H ₂ (CH ₄ , C ₃ H ₈ , CO) gas, or pyrolysis gas of methanol is used as the carbon source, and the temperature is 300 to 600 ° C. over 1 to 24 hours. The flakes 15 are heated and carbonized. In addition, solid carbonization using carbon powder or molten salt carburization using KCN or NaCN can be performed. H and P can also be subjected to normal hydrogenation and phosphation.

<Heat treatment process>
Furthermore, in the manufacturing method of this indication, you may heat-process the flake 15 obtained at the said process at 800-1300 degreeC for 2 to 120 hours. By this heat treatment, a phase having a ThMn ₁₂ type crystal structure (hereinafter sometimes referred to as “ThMn ₁₂ phase”) is homogenized, and both the anisotropic magnetic field and saturation magnetization characteristics are further improved. The pulverization of the flakes 15 may be performed before the heat treatment or after the heat treatment.

If the heat treatment temperature is 800 ° C. or higher, the ThMn ₁₂ phase can be homogenized. From the viewpoint of homogenizing the ThMn ₁₂ phase, 900 ° C or higher is preferable, 1000 ° C or higher is more preferable, and 1100 ° C or higher is even more preferable. On the other hand, when the heat treatment temperature is 1300 ° C. or lower, there is little possibility that the structure of the magnetic compound is decomposed and an α-Fe phase is generated. From this viewpoint, 1250 ° C. or lower is preferable, 1200 ° C. or lower is more preferable, and 1150 ° C. or lower is even more preferable.

  Hereinafter, the magnetic compound of the present disclosure, the production method thereof, and the magnetic powder will be described more specifically with reference to Examples and Comparative Examples. In addition, the magnetic compound of this indication, its manufacturing method, and a magnetic powder body are not limited to the conditions used in the following Examples.

《Sample preparation》
A sample of the magnetic compound was prepared as follows.

A melt having the composition shown in Table 1 was prepared, quenched at a rate of 10 ⁴ K / sec by a strip casting method, a quenched flake was prepared, and heat treatment was performed at 1200 ° C. for 4 hours in an Ar atmosphere. Next, the flakes were pulverized using a cutter mill in an Ar atmosphere, and particles having a particle size of 20 μm or less were collected. These particles were placed in nitrogen gas having a purity of 99.99% and subjected to nitriding at 450 ° C. for 4 hours.

<< Evaluation of Sample >>
From the SEM image (reflected electron image) of the obtained particles (before nitriding), the size and area ratio of the α-Fe phase were measured, and the content ratio (volume%) of the α-Fe phase as area ratio = volume ratio. Was calculated. Further, X-ray diffraction (XRD) of the obtained particles (before nitriding) was performed, and ThMn ₁₂ crystallinity was calculated by the method described above. Further, the nitrogen amount and magnetic properties of the obtained particles (after nitriding) were measured. The amount of nitrogen was calculated from the change in weight before and after nitrogenation.

  The saturation magnetization and anisotropic magnetic field of the obtained particles (after nitriding) were measured based on the saturation asymptotic rule using a vibrating sample magnetometer (VSM). For the vibrating sample magnetometer (VSM), a magnetometer capable of applying a magnetic field up to 9T (7.2 MA / m) was used. About the measurement sample, the particles after nitriding were filled in an acrylic resin container (inner dimensions: diameter 5 mm, height 5 mm), and solidified with paraffin resin.

  The results (before nitriding) are shown in Table 1. In Table 1, with respect to the overall composition of the magnetic compound, a sample was taken from the magnetic compound and analyzed by ICP emission spectroscopy. Since a small amount of inevitable impurities were detected as M, the breakdown of the content of M is shown in Table 2. In addition, ppm in Table 2 is ppm by mass. The analysis results in Table 1 were almost the same as the charged composition of the molten metal. From the analysis results in Table 1, the relationship between the Zr content ratio x, the rare earth site content a, and the Ti content c was summarized for the overall compositions of Examples 1-7 and Comparative Examples 1-8. The graph is shown in FIG.

As can be seen from Table 1 and FIG. 1, in the samples of Examples 1 to 7, the entire composition of the magnetic compound is in an appropriate range, so the content of the α-Fe phase is 2% by volume or less. I was able to confirm that. In Example 1-7, it was confirmed that ThMn ₁₂ type crystallinity is equal to or greater than 50% by volume.

  On the other hand, in the samples of Comparative Examples 2 to 4 and 6 to 8, it was confirmed that the content of the α-Fe phase exceeded 2% by volume because the overall composition of the magnetic compound was not in the proper range. .

  In the sample of Comparative Example 1, although the content of the α-Fe phase is 2% by volume or less, the magnetic compound does not contain Zr (z = 0), and the magnetic compound is exposed to a high temperature (600 ° C.). , And may decompose to produce an α-Fe phase.

In the sample of Comparative Example 2, the content ratio x of Zr exceeds the upper limit of the present invention at the rare earth site represented by Nd _(1-xy) R _y Zr _x , and an Fe ₂ Zr phase is generated. It had been. FIG. 5 is a view showing an SEM image of the sample of Comparative Example 5 (before nitriding). In FIG. 5, the formation of the Fe ₂ Zr phase is observed at the position indicated by the arrow.

  Regarding the entire composition of the magnetic compound, there are a method of displaying the contents of rare earth sites, iron group sites, Ti, and M in atomic% and a method of displaying them in molar ratio. Table 3 shows the overall composition of the magnetic compound (before nitriding) by both methods for reference. In addition, since the content of M is very small, the display of the content of M is omitted in the molar ratio display.

  The magnetic compound has a magnetic phase and a grain boundary phase. When the EPMA ZAF method is used, the composition of the magnetic phase can be measured separately from the composition of the grain boundary phase. Table 4 summarizes the measurement results of the composition of the magnetic phase for the magnetic compound before nitriding. Table 4 shows the overall composition of the magnetic compound shown in Table 1. In Table 4, the composition of the magnetic phase is indicated by both the method of displaying the rare earth site, the iron group site, and the Ti content by atomic% and the method of displaying by molar ratio. Since the content of M is very small, the composition of the magnetic phase is indicated by omitting the content of M.

  From Table 4, FIG. 6 is a graph summarizing the content ratio x ′ of Zr and the content p of rare earth sites for the compositions of the magnetic phases of Examples 1 to 7 and Comparative Examples 1 to 8.

  As can be seen from FIG. 6, the compositions of the magnetic phases of Examples 1 to 7 and Comparative Examples 1 to 8 were in a linear relationship (proportional relationship), and it was confirmed that the inclination was positive.

  Table 5 shows the magnetic properties of the magnetic compound after nitriding.

  As can be seen from Table 5, the samples of Examples 1 to 7 have a high anisotropy of 6.32 to 6.99 (MA / m) while maintaining a high saturation magnetization of 1.55 to 1.61 T. It was confirmed that a magnetic field was achieved. This is presumably because the content of the α-Fe phase in the magnetic compound is 2% by volume or less. In addition, it is thought that the content of the α-Fe phase of the magnetic compound is the same before and after nitriding.

  Further, as can be seen from Table 5, the anisotropic magnetic field is 7.2 MA / m or less for all the samples, and this value is the maximum applied magnetic field 9T (7. 2 MA / m) or less, it is considered that saturation magnetization and anisotropic magnetic field were correctly measured in all samples.

For reference, the values measured using a vibrating sample magnetometer with a maximum applied magnetic field of 5 T (4 MA / m) are extrapolated from the results of samples with known saturation magnetization and anisotropic magnetic field, and Comparative Example 7 and When the saturation magnetization and anisotropic magnetization of 8 were obtained, the following results were obtained.
Comparative Example 7: Saturation magnetization 1.56T, anisotropic magnetic field 7.6 MA / m
Comparative Example 8: Saturation magnetization 1.57 T, anisotropic magnetic field 7.8 MA / m
In either case, the values were higher than those measured using a vibrating sample magnetometer (VSM) having a maximum applied magnetic field of 9 T (7.2 MA / m).

  From the contents described so far, the effects of the magnetic compound of the present disclosure, the production method thereof, and the magnetic powder have been confirmed.

DESCRIPTION OF SYMBOLS 10 Quench apparatus 11 Melting furnace 12 Molten metal 13 Tundish 14 Cooling roll 15 Thin piece

Claims (10)

Formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d A e
(In the above formula, R is one or more rare earth elements other than Nd,
T is one or more elements selected from the group consisting of Ti, V, Mo and W,
M is an inevitable impurity element and one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au,
A is one or more elements selected from the group consisting of N, C, H and P, and
0 <x ≦ 0.3,
0 ≦ y ≦ 0.1,
0 ≦ z ≦ 0.3,
7.7 <a ≦ 9.4,
b = 100-acd,
3.1 ≦ c <7.7,
0 ≦ d ≦ 1.0, and
1 ≦ e ≦ 18)
Having a composition represented by
In the above formula, the relationship of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 is satisfied, and
It has a ThMn ₁₂ type crystal structure,
Magnetic compound.   The magnetic compound according to claim 1, wherein 3.1 ≦ c ≦ 7.3.   The magnetic compound according to claim 1, wherein 7.7 <a ≦ 8.7 in the formula. Formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d
(In the above formula, R is one or more rare earth elements other than Nd,
T is one or more elements selected from the group consisting of Ti, V, Mo and W,
M is an inevitable impurity element and one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au, and
0 <x ≦ 0.3,
0 ≦ y ≦ 0.1,
0 ≦ z ≦ 0.3,
7.7 <a ≦ 9.4,
b = 100-acd,
3.1 ≦ <c <7.7, and
(0 ≦ d ≦ 1.0)
And having a composition represented by:
Preparing a molten metal satisfying the relationship of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 in the formula,
Quenching the molten metal at a rate of 1 × 10 ² to 1 × 10 ⁷ K / sec to obtain flakes; and
Intruding A (one or more elements selected from the group consisting of N, C, H and B) into the flakes;
The manufacturing method of the magnetic compound of Claim 1 containing this.   The method of claim 4, further comprising grinding the flakes prior to the intrusion to obtain a powder.   The method of claim 5, further comprising heat treating the flakes at 800-1300 ° C. for 2-120 hours.   The method according to claim 5 or 6, further comprising heat-treating the powder at 800 to 1300 ° C for 2 to 120 hours.   The method according to any one of claims 4 to 7, wherein 3.1≤c≤7.3 in the formula.   The method according to any one of claims 4 to 8, wherein 7.7 <a ≦ 8.7 in the formula. Formula _{(Nd (1-x-y} ) R y Zr x) a (Fe (1-z) Co z) b T c M d A e
(In the above formula, R is one or more rare earth elements other than Nd,
T is one or more elements selected from the group consisting of Ti, V, Mo and W,
M is an inevitable impurity element and one or more elements selected from the group consisting of Al, Cr, Cu, Ga, Ag and Au,
A is one or more elements selected from the group consisting of N, C, H and P, and
0 <x ≦ 0.3,
0 ≦ y ≦ 0.1,
0 ≦ z ≦ 0.3,
7.7 <a ≦ 9.4,
b = 100-acd,
3.1 ≦ c <7.7,
0 ≦ d ≦ 1.0, and
1 ≦ e ≦ 18)
Having a composition represented by
In the above formula, the relationship of a ≧ 1.6x + 7.7 and c ≧ −14x + 7.3 is satisfied, and
It has a ThMn ₁₂ type crystal structure,
Magnetic powder.