JPH06168807A - Magnetic material and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide high magnetic characteristic by specifying a composition of each component element of R Fe-M-N magnetic alloy and by specifying a crystal structure of polycrystal which forms a main phase of the alloy as rhombohedral or hexagonal mainly composed of R, Fe and N. CONSTITUTION:This material is composed of a substance which is expressed by RwFexMyNz wherein, R is at least one kind of element selected from rare earth elements containing Y, M is at least one kind of element selected from Cu and In, and w, x, y, z show atomic percentage of each component element and satisfy 3<=w<=20, 25<=x<=93.95, 0.05<=y<=50, 3<=z<=30, simultaneously.) and its main phase forms a rhombohedron or a hexagon R, Fe, N-based polycrystal. It is a magnetic material whose average distance between crystal grains is 0.01 to 3mum having a fine structure wherein an M element-based phase exists between crystal grains. Thereby, a magnetic material having both high magnetic characteristic and good oxidation resistance can be acquired.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is particularly applicable to small motors,
The present invention relates to a rare earth-based magnetic material that has high magnetic properties and is excellent in oxidation resistance, which is optimal for applications such as actuators.

[0002]

2. Description of the Related Art Magnetic materials are used for home appliances, acoustic products,
It is used in a wide range of fields including automobile parts and peripheral devices for computers, and its importance as an electronic material is increasing year by year. In particular, recently, there has been a demand for miniaturization and high efficiency of various electric / electronic devices, so that a magnetic material with higher performance is required.

In response to the demands of this era, Sm-Co type, N
The demand for rare earth magnetic materials such as d-Fe-B is rapidly increasing. However, the Sm-Co based magnetic material has a problem that the raw material supply is unstable and the raw material cost is high, and the Nd-Fe-B based magnetic material is inferior in heat resistance and corrosion resistance.
On the other hand, as a new rare earth magnetic material, rare earth-Fe-
N magnetic materials have been proposed (for example, JP-A-2-57).
663). This material has a magnetization, an anisotropic magnetic field,
The Curie point is high, and the above-mentioned Sm-Co system and Nd-Fe-
It is expected as a magnetic material that supplements the drawbacks of B-based magnetic materials.

However, when this rare earth-Fe-N-based material is used after being finely pulverized, the surface is oxidized and the coercive force is lowered, and the high magnetic characteristics originally possessed by this material are sufficiently exhibited. There was a problem that I could not.
As a countermeasure against this, rare earth-Fe-N-based materials are added to Cu, In
A method of improving the coercive force by incorporating a metal component M such as the above is considered, and regarding this rare earth-Fe-M-N-based material, JP-A-62-269303 and JP-A-62-136551. It is disclosed in the gazette and the like.

[0005]

However, in the rare earth-Fe-M-N based magnetic materials disclosed in the above-mentioned respective publications, only the contents of the respective component elements are specified,
Its crystal structure and microstructure are not specified. Further, according to the disclosure of the above-mentioned publication, since these magnetic materials are manufactured by melting and sintering each component element and their nitrides, iron nitride, α-iron, rare earth nitrides are actually used. , M,
And those containing a large amount of M nitride are obtained. Therefore, magnetic properties such as coercive force were often not improved as expected, but rather deteriorated.

According to the present invention, not only the content of each component element in the alloy constituting the magnetic material is specified, but also the crystal structure and the microstructure are specified so that high magnetic properties and excellent oxidation resistance can be obtained. It is an object of the present invention to provide a rare earth-Fe-MN magnetic material and a method for producing the same.

[0007]

In order to achieve the above object, the magnetic material according to claim 1 has the general formula R _w Fe _x M _y N _z.
(Wherein R is at least one element selected from rare earth elements including Y, M is at least one element selected from Cu and In, w,
x, y, and z represent atomic percentages of each component element, and simultaneously satisfy the following expressions (1) to (4). ) 3 ≦ w ≦ 20 (1) 25 ≦ x ≦ 93.95 (2) 0.05 ≦ y ≦ 50 (3) 3 ≦ z ≦ 30 (4) The main phase is R Is a rhombohedral or hexagonal polycrystal having Fe, Fe, and N as main components, and has an average distance between crystal grains of 0.01 to 3 μm, and mainly includes the M component between crystal grains. It is characterized by having a microstructure in which phases are present.

The magnetic material according to claim 2 is characterized in that 0.01 to 50 atomic% of the Fe component is replaced with Co. Further, claim 3 provides a method for producing such a magnetic material, which is represented by the general formula _{Rw / (100-z)} Fex _{/ (100-z) My / (100-z)} . Is
(However, R is at least one element selected from rare earth elements including Y, M is at least one element selected from Cu and In, and w, x, and y represent the atomic percentage of each component element, z represents the content [atomic percentage] of N added later, and w, x, y, and z are the following (1) to (4).
Satisfy the formula at the same time. ) 3 ≦ w ≦ 20 (1) 25 ≦ x ≦ 93.95 (2) 0.05 ≦ y ≦ 50 (3) 3 ≦ z ≦ 30 (4) The main phase is R Is a rhombohedral or hexagonal polycrystal having Fe, Fe, and N as main components, and has an average distance between crystal grains of 0.01 to 3 μm, and mainly includes the M component between crystal grains. R-Fe- having a microstructure in which phases are present
It is characterized in that the M-based alloy is subjected to nitriding treatment under a temperature condition of 200 to 650 ° C. in an atmosphere containing at least one of nitrogen gas and ammonia gas.

The rare earth element (R) which is a component element of the magnetic material according to claims 1 and 2 is Y, La or C.
e, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
Examples include y, Ho, Er, Tm, Yb, and Lu. This magnetic material must contain at least one of these elements. Therefore, a substance containing two or more kinds of rare earth elements such as misch metal or didymium may be used. Preferred rare earth elements are Y and C
e, Pr, Nd, Sm, Gd, Dy, and Er. More preferred are Y, Ce, Pr and N.
d, and Sm.

The rare earth element (R) used here may be of a purity that can be obtained by industrial production, and impurities such as O, H, C, A which cannot be mixed in during production are inevitable.
It does not matter even if 1, 1, Si, F, Na, Mg, Ca, Li or the like is present. Iron (Fe), which is a component element of the magnetic material, is a basic component responsible for ferromagnetism in this magnetic material, and it is necessary to contain 25 atomic% or more of this iron component. In addition, 0.01% of this iron component
˜50 atomic% can be replaced by Co, and the introduction of Co can raise the Curie point and the magnetization and also improve the oxidation resistance. In the following, when expressed as an iron component, 0.01 to 50 atomic% of Fe is replaced with Co.

Metal (M) which is a component element of the magnetic material
Is at least one element selected from Cu and In, but as M ′ component, Ga, Al, Zn, Sn,
Mn, Cr, Ni, Li, Na, K, Mg, Ca, S
r, Ba, Ti, Zr, Hf, V, Nb, Ta, Mo,
W, Pd, Ag, B, C, Si, Ge, Pb, and B
One or more of the elements of i may be contained together with Cu and / or In. in this case,
The content of these does not exceed the total amount of Cu and In, and the total amount of Cu and / or In is 0.
It should be in the range of 05 to 50 atomic%.

The composition of the rare earth element, the iron component, M, and nitrogen in the magnetic material is such that the rare earth element component is 3 to 3.
The content is 20 at%, the iron content is 25 to 93.95 at%, the M content is at 0.05 to 50 at%, and the nitrogen content is at 3 to 30 at%, which are simultaneously satisfied. When the rare earth element component is less than 3 atomic%, the soft magnetic phase containing a large amount of iron component is separated, and the coercive force of the nitride is lowered, so that a practical permanent magnet cannot be obtained. If the rare earth element content exceeds 20 atom%,
The residual magnetic flux density is lowered, which is not preferable.

The effect of adding the M component to the R-Fe-N system magnetic material is mainly to improve the oxidation resistance. M component is 0.
If it is less than 05 atom%, the effect of adding M as described above cannot be exhibited, which is not preferable. When it exceeds 50 atom%, the saturation magnetization is lowered, which is not preferable, and the preferable range of the amount of M component is 0.1 to 30 atom%. In addition, M
Depending on the preparation method and conditions of the mother alloy, the addition of the component causes the M component to be condensed in the subsurface phase exhibiting soft magnetism, such as the grain surface, the vicinity of the grain boundary, or the R-rich nitride phase such as the RFe ₃ phase. By making the sub-phase non-magnetic, the squareness ratio and coercive force of the nitride may be improved.

As will be described later, by introducing nitrogen into the R-Fe-M alloy, expansion occurs in the crystal lattice of the R-Fe-M alloy, and oxidation resistance and magnetic properties can be improved. When the nitrogen component is less than 3 atomic%, such an effect cannot be sufficiently exhibited, which is not preferable. If it exceeds 30 atomic%, the magnetization becomes low, and the practical use as a magnet material becomes small, which is not preferable. A more preferable range for the content of the nitrogen component is 5 to 25 atom%, and a particularly preferable range is 10 to 23 atom%.

The optimum content of nitrogen component is the target R
In the case where Pr _12.2 Fe _79.0 In _8.8 having a rhombohedral structure is selected as the raw material alloy, it depends on the R-Fe-M composition ratio of the -Fe-MN magnetic material, the abundance ratio of the main phase, and the crystal structure. The optimum nitrogen content is 1
It is around 4 to 15 atom%. The optimum nitrogen amount here depends on the purpose, but the optimum amount of nitrogen is the oxidation resistance and some of the many magnetic properties of the resulting magnetic material. , The temperature change rate of coercive force, the absolute value of the thermal demagnetization rate, and the magnetic anisotropy ratio are minimum, and other magnetic characteristics are maximum.

On the other hand, in the magnetic materials of claims 1 and 3, the crystal structure of the main phase is specified as a rhombohedral or hexagonal crystal containing R, Fe, and N as main components. The main phase of such a crystal structure is obtained by introducing nitrogen into an R-Fe-M alloy (mother alloy) having a crystal structure having almost the same symmetry as that of a rhombohedral crystal or a hexagonal crystal, that is, nitrogen is added to the crystal of the above crystal. Either enter the interstitial lattice or one of the constituent elements (mainly M)
It is obtained by substituting

By introducing nitrogen into such a master alloy,
The crystal lattice often expands. The expansion of the crystal lattice improves the oxidation resistance and at least one of the following magnetic characteristics. The magnetic properties include the saturation magnetization (4πIs) of the material, the residual magnetic flux density (Br), the magnetic anisotropic magnetic field (Ha), the magnetic anisotropic energy (Ea),
Magnetic anisotropy ratio, Curie point (Tc), intrinsic coercive force (iH
c), squareness ratio (Br / 4πIs), maximum energy product [(BH) max], thermal demagnetization rate (α), and coercive force temperature change rate (β). Here, the magnetic anisotropy ratio is
It is the ratio (a / b) of the magnetization (a) in the difficult magnetization direction and the magnetization (b) in the easy magnetization direction when an external magnetic field of 15 kOe is applied. The smaller the magnetic anisotropy ratio, the greater the magnetic anisotropy. It is evaluated as high in energy.

For example, when Sm _17.1 Fe _74.6 Cu _8.3 having a rhombohedral structure is selected as the mother alloy, by introducing nitrogen, the crystal magnetic anisotropy is suitable as a hard magnetic material due to its in-plane anisotropy. Uniaxial anisotropy, and the magnetic characteristics including the magnetic anisotropy energy and the oxidation resistance are improved. The magnetic material according to claims 1 and 2 must contain 50% by volume or more of the main phase having the above-described crystal structure,
In addition to this, R and F having another crystal structure as a subphase
A phase mainly composed of e and N or a phase having a different composition may be contained.

For example, it is possible to include a highly magnetic nitride phase having a tetragonal structure, such as the RFe _12-y M ′ _y N _z phase, but in order to fully exert the action of the main phase. , It is necessary to keep its content lower than that of the main phase. It is extremely preferable for practical purposes that the content of the main phase exceeds 75% by volume. Further, by selecting the production conditions of the master alloy, the main phase of the master alloy is made to be a rhombohedral or hexagonal polycrystal having R and Fe as the main components, and its microstructure is described above between the crystal grains. A phase mainly composed of the M component may be present.

R obtained by producing a master alloy having such a structure under specific production conditions and introducing nitrogen into the master alloy
Among the —Fe—M—N magnetic materials, those having an average distance between crystal grains of 0.01 to 0.2 μm are pinning type magnetic materials. The pinning type magnetic material is a material having extremely high oxidation resistance because it can reduce a decrease in coercive force even if a soft magnetic component is generated on the grain surface due to slight oxidation.

Among the R-Fe-M-N based magnetic materials, those having an average distance between crystal grains of 0.2 to 3 μm may generate an M component between crystal grains even if the surface of the powder is oxidized. Since the main phase is present, it is presumed that the presence of this M component suppresses the oxidation inside the crystal grains, so that the material has extremely high oxidation resistance. The average distance between crystal grains is 3 μm.
If it exceeds, the absolute value of the coercive force becomes small and the oxidation resistance becomes poor, which is not preferable.

Therefore, in the magnetic materials according to the first and second aspects, the average distance between the crystal grains is 0.01 to 3 μm. A more preferable range of the average distance between crystal grains is 0.03 to 1 μm. The average distance between the crystal grains described above is a value obtained by measuring the distance connecting the centers of one crystal grain and the crystal grain closest to the crystal grain for n crystal grains and calculating the arithmetic mean.

Further, the magnetic materials according to claims 1 and 2 may have a microstructure in which inclusions mainly composed of the M component are dispersed in the main phase. Magnetic force and oxidation resistance are improved. Such R-Fe-M-N
The magnetic material preferably contains hydrogen (H) in the range of 0.01 to 15 atomic%, and further contains oxygen (O) in the range of 0.
It is preferably contained in the range of 01 to 15 atomic%. More preferable hydrogen content and oxygen content are both 0.1 to 10
It is in the atomic% range.

Therefore, R in claims 1 and 2
A particularly preferable composition of the —Fe—MN magnetic material is R _w
When expressed in _{Fe x M y N z H u} O v, w representing the atomic percentage of each component element, x, y, z, u , v are the following (5)
To (10) are satisfied at the same time. 3 ≦ w ≦ 20 (5) 25 ≦ x ≦ 92 (6) 0.1 ≦ y ≦ 30 (7) 10 ≦ z ≦ 23 (8) 0.1 ≦ u ≦ 10 ... (9) 0.1 ≦ v ≦ 10 (10) In the manufacturing method according to claim 3, the main phase is a rhombohedral or hexagonal polycrystal containing R and Fe as main components, and a crystal. The average distance between grains is 0.01 to 3 μm,
An R-Fe-M-based alloy having a microstructure in which a phase mainly composed of the M component is present between crystal grains is used in an atmosphere containing at least one of nitrogen gas and ammonia gas.
The nitriding treatment is performed under a temperature condition of 0 to 650 ° C., but more specific methods will be described below for each item. <Preparation of mother alloy> As a method for producing the R-Fe-M alloy,
A) High frequency melting method in which all component metals are melted by high frequency and cast in a mold, b) Arc melting method in which all component metals are charged in a boat made of copper and melted by arc discharge, c) High frequency molten metal A superquenching method to obtain a ribbon-shaped alloy by dropping it on a rotated copper roll.
D) Gas atomization method of spraying a high-frequency molten metal with a gas to obtain an alloy powder, e) Fe component and / or M component powder, or Fe-M alloy powder, and R and / or M oxide The powder and the reducing agent are reacted at high temperature,
R / D method of diffusing R or R and M into Fe and / or Fe-M alloy powder while reducing R or R and M, f) simple substance and / or alloy of each component metal, ball mill, etc. Mechanical alloying method of reacting while finely pulverizing with, g) heating the alloy obtained by any of the above methods under a hydrogen atmosphere, and once with R and / or M hydride, Fe and / or M or Fe- Any of the HDDR methods of decomposing into an M alloy and then recombining while decompressing hydrogen at a high temperature under low pressure to form an alloy may be used.

When the high frequency melting method or the arc melting method is used, when the alloy is solidified from the molten state, the soft magnetic component mainly composed of Fe tends to be precipitated. This soft magnetic component causes a decrease in coercive force especially after the nitriding step.
Therefore, it is desirable to appropriately adjust the melting conditions, the material of the mold and the thickness of the voids, and the like, and it is desirable to take a method of sufficiently increasing the cooling rate.

Further, annealing in an inert gas such as argon or helium or in vacuum at a temperature range of 600 ° C. to 1300 ° C. eliminates the soft magnetic component and controls the microstructure of the obtained alloy. be able to. The alloy produced by this method has better crystallinity and higher residual magnetic flux density than those produced by the ultra-quenching method.

When the ultraquenching method is used, fine crystal grains are obtained, and submicron particles can be prepared depending on the conditions. However, when the cooling rate is high, the alloy becomes amorphous and the magnetic properties such as magnetization are deteriorated even after nitriding. Also in this case, the annealing after the alloy preparation as described above is effective. Since alloys obtained by the gas atomization method often have spherical crystal grains, the grain size can be adjusted in a wide range from fine powder to coarse powder depending on the gas flow rate and the temperature condition of the molten metal. It is possible. Also in this case, depending on the conditions, it is necessary to perform the above-mentioned annealing to improve the crystallinity.

In the alloy prepared by the R / D method, the mechanical alloying method, and the HDDR method, the grain size is 0.0
Since it is possible to adjust to a fine size of 1 to 3 μm and to arbitrarily adjust the composition and distribution state of the M-component main phase, a phase mainly composed of the M component between the crystal grains of the main phase. Easy to exist. The conditions for annealing the mother alloy are selected within the above range depending on the composition of the mother alloy and the characteristics of the target magnetic material. For example, in order to prevent the coercive force from being deteriorated by oxidation by allowing a phase mainly composed of the M component to exist between the crystal grains of the Sm ₂ Fe ₁₇ N _x main phase, 600 to 1100 in an inert gas atmosphere can be used. It is desirable to perform heat treatment within the temperature range of ° C. <Coarse crushing and classification> It is possible to directly nitride and heat treat the alloy ingot produced by the above method, but if the crystal grain size is larger than 500 μm, the nitriding time will be longer, so after performing coarse crushing, nitriding is performed. It is more efficient to do so.

The coarse pulverization is carried out by using a jaw crusher, a hammer, a stamp mill, a rotor mill, a pin mill, a coffee mill or the like. Even if a crusher such as a ball mill or a jet mill is used, an alloy powder having a size suitable for nitriding can be prepared depending on the conditions. In addition, after coarsely pulverizing, if the particle size is adjusted with a sieve, a vibrating or sonic classifier, a cyclone, or the like, the nitriding treatment is performed more uniformly.

If the magnetic powder obtained by coarse pulverization and classification is annealed in an inert gas or hydrogen, it may be possible to remove structural defects. <Nitriding / annealing> R-Fe-M obtained by the above method
A gas containing a nitrogen source such as ammonia gas or nitrogen gas is brought into contact with the alloy powder or ingot to introduce nitrogen into the crystal structure.

At this time, coexistence of hydrogen in the nitriding atmosphere gas is preferable because the nitriding efficiency is high and the nitriding can be performed while the crystal structure remains stable. Moreover, in order to control the nitriding reaction, an inert gas such as argon, helium, or neon may be allowed to coexist. The nitriding reaction can be controlled by changing conditions such as gas composition, heating temperature, heat treatment time, and pressure.

The heating temperature varies depending on the composition of the mother alloy and the nitriding atmosphere, but is in the range of 200 to 650 ° C. A preferable temperature range is 250 to 600 ° C. Further, after nitriding, annealing in an inert gas and / or hydrogen gas can further improve the magnetic characteristics. Examples of the nitriding / annealing device include a horizontal or vertical tubular furnace, a rotary reaction furnace, and a closed reaction furnace. In particular, it is preferable to use a rotary reactor in order to obtain a powder having a uniform nitrogen composition distribution.

The gas used for the reaction may be supplied by an air flow system in which a gas flow of 1 atm or more is fed into the reaction furnace while keeping the gas composition constant, or an encapsulation system in which the gas is sealed at 0.01 to 70 atm. Alternatively, there is a method that combines them. The optimum treatment conditions in such nitriding treatment depend on whether the mother alloy is an ingot or a powder, and when it is a powder, it depends on the surface condition, the crystal grain size, the pulverized grain size, and the microstructure. In the case of an ingot, it depends on the surface condition, the microstructure, and the like.

In particular, in order to obtain a practical hard magnetic material, the following treatment may be followed by the following pulverization, magnetic field molding, and magnetization. <Fine pulverization> The fine pulverization method is selected according to the amount of hydrogen or oxygen contained in the magnetic material and the target pulverized particle size. The crushing device used includes a rotary ball mill, a vibrating ball mill, a planetary ball mill, a wet mill, a jet mill, a cutter mill, a pin mill, and an automatic mortar. These may be combined and pulverized in two or more stages.

In this step, M component is further added,
By performing heat treatment before or after the next <magnetic field forming> step to obtain various magnet materials, the squareness ratio and the absolute value of the coercive force can be improved. <Magnetic field molding> When the magnetic powder thus obtained is applied to an anisotropic bonded magnet, it is mixed with a thermosetting resin or a metal binder and then compression-molded in a magnetic field or a thermoplastic resin. Magnetic field molding is performed by, for example, performing injection molding in a magnetic field after kneading. Such magnetic field shaping is preferably 10 kO in order to obtain sufficient magnetic field orientation.
e or more, and more preferably in a magnetic field of 15 kOe or more.

When producing an anisotropic bonded magnet, the M component is also used as a metal binder or a surface treatment agent. <Magnetization> The sintered magnet material or the anisotropic bonded magnet material obtained as described above is usually magnetized to enhance its magnet performance.

This magnetization is performed using, for example, an electromagnet that generates a static magnetic field, a condenser magnetizer that generates a pulsed magnetic field, and the like. In order to perform sufficient magnetization, set the magnetic field strength to
Preferably 15 kOe or more, more preferably 30 kOe
e or more.

[0038]

According to the present invention, the composition of each component element in the R-Fe-MN magnetic material is specified by the equations (1) to (4), and the main phase of the alloy is defined. By specifying the crystal structure of the crystal as a rhombohedral crystal or a hexagonal crystal containing R, Fe, and N as the main components, high magnetic characteristics can be imparted to the R-Fe-MN magnetic material.

Further, the average distance between crystal grains in this polycrystal is 0.01 to 3 μm, and a microstructure in which a phase mainly composed of the above-mentioned M component is present between crystal grains is used to obtain the following: For that reason, the oxidation resistance can be made extremely high. That is, the average distance between crystal grains is 0.01 to 0.
Those having a thickness of 2 μm are pinning type magnetic materials.
The pinning type magnetic material is a material having extremely high oxidation resistance because it can reduce a decrease in coercive force even if a soft magnetic component is generated on the grain surface due to slight oxidation.

When the average distance between the crystal grains is 0.2 to 3 μm, even if the surface of the powder is oxidized, a phase mainly containing the M component exists between the crystal grains. Since it is assumed that the presence of the components suppresses the oxidation inside the crystal grains,
The material has extremely high oxidation resistance. According to claim 2,
By introducing Co, the Curie point and the magnetization are increased, and the oxidation resistance can be improved.

According to the third aspect, the main phase is a rhombohedral or hexagonal polycrystal containing R and Fe as main components, and the average distance between crystal grains is 0.01 to 3 μm.
An R-Fe-M-based alloy having a microstructure in which a phase mainly composed of the M component is present between crystal grains is used in an atmosphere containing at least one of nitrogen gas and ammonia gas.
Nitrogen infiltrates between the crystal lattices of the main phase composed of R-Fe by performing a nitriding treatment under a temperature condition of ~ 650 ° C.
It is replaced by the element that forms the component.

As a result, the main phases are R, Fe and N.
Is a rhombohedral or hexagonal polycrystal having as a main component, an average distance between crystal grains of 0.01 to 3 μm, and a phase mainly containing the M component is present between the crystal grains. It is possible to obtain an R-Fe-M-N alloy having a fine structure.

[0043]

EXAMPLES Examples of the present invention will be shown below. The measuring method and the evaluating method of each characteristic are as follows. << Magnetic Properties >> The intrinsic coercive force was evaluated.

That is, R-Fe- having an average particle size of about 7 μm
MN magnetic powder in an external magnetic field of 15 kOe for 12 to
Molded to a size of 5 mm x 10 mm x 2 mm at n / cm ² ,
The molded body was pulse-magnetized under a magnetic field of 60 kOe at room temperature, and then the intrinsic coercive force (iHc / kOe) was measured by a vibrating sample magnetometer (VSM). <Nitrogen amount, oxygen amount, and hydrogen amount> The nitrogen amount and oxygen amount are
Si ₃ N ₄ (containing a fixed amount of SiO ₂ ) as a standard sample,
It was quantified by the inert gas melting method. The amount of hydrogen was quantified by an inert gas melting method using high-purity hydrogen gas (99.999%) as a standard gas. << Average particle size >> Measured using a Lee-Nurse specific surface area meter. << Oxidation resistance-1 >> The intrinsic coercive force retention rate (%) before and after holding at 110 ° C. for 200 hours was evaluated.

That is, the molded product whose intrinsic coercive force (A) was evaluated as described above was placed in a thermostatic chamber at 110 ° C. and held for 200 hours, and then the intrinsic coercive force (B) was measured in the same manner as described above. Then, B / A was calculated. The higher the retention rate, the higher the oxidation resistance performance. In particular, in this test, evaluation was performed without adding various binders, so that a material having a retention rate of more than 70% can be determined to be a material that can be sufficiently used as a practical physical property when used as a bonded magnet, for example. << Oxidation resistance-2 >> 10 mg of a coarse powder sample adjusted to have an average particle size of 15 μm was placed in a thermobalance and heated from 50 ° C. to 250 ° C. at a rate of 10 ° C./min in an air stream of 50 ml / min. The rate of change in weight (% by weight) was measured. The smaller the weight change rate, the less likely it is to be oxidized. <Example 1> Sm having a purity of 99.9%, Fe having a purity of 99.9%, and Cu having a purity of 99.9% were melt-mixed in a high-frequency melting furnace under an argon gas atmosphere, and further in an argon atmosphere. , 940 ° C for 7 hours, then 900 ° C for 10 hours
By annealing for 0 hour, Sm _13.2 Fe _78.1 Cu _8.7
An alloy of composition was prepared.

This alloy was crushed by a jaw crusher and then further crushed by a rotor mill in a nitrogen atmosphere, and the particle size was adjusted by a sieve to obtain a powder having an average particle size of about 50 μm. This Sm-Fe-Cu alloy powder was charged into a horizontal tubular furnace and the ammonia partial pressure was 0.32 at 450 ° C.
After heat treatment in a mixed gas flow of atm and hydrogen gas of 0.68 atm, followed by annealing in an argon gas flow, the average particle size was adjusted to about 15 μm. Next, this coarse powder was pulverized by a jet mill to an average particle size of about 7 μm.

At this time, as the crushing gas, a gas mainly containing nitrogen and partially mixed with oxygen and water vapor was used.
Table 1 also shows the composition of the obtained Sm-Fe-Cu-N-based powder and the evaluation result of the oxidation resistance performance. The molded product of the Sm-Fe-Cu-N-based powder pulverized to 7 μm had an intrinsic coercive force of 10.5 kOe and a residual magnetic flux density of 7.4 kG.
As a result of analysis by an X-ray diffraction method, this material was a polycrystal composed mainly of rhombohedral crystals.

As a result of analysis by SEM and TEM photographs, the average distance between crystal grains was 0.1 μm, and a phase mainly composed of Cu was recognized between crystal grains. Example 2 Sm having a purity of 99.9%, Fe having a purity of 99.9%, and In having a purity of 99.9% were melt-mixed in a high-frequency melting furnace under an argon gas atmosphere, and further in an argon atmosphere. 1050 ° C for 1 hour, then 800 ° C for 5 hours
By annealing for 0 hour, Sm _12.8 Fe _81.1 In _6.1
An alloy of composition was prepared.

Thereafter, in the same manner as in Example 1, the average particle size is 15
A coarse powder of μm was obtained, and an Sm—Fe—In—N-based powder having the composition shown in Table 1 and an average particle size of 7 μm was obtained. The molded product made of 7 μm powder had an intrinsic coercive force of 7.3 kOe and a residual magnetic flux density of 6.5 kG. As a result of analysis by an X-ray diffraction method, this material was a polycrystal composed mainly of rhombohedral crystals.

As a result of analysis by SEM and TEM photographs, the average distance between the crystal grains was 2.3 μm, and a phase mainly composed of In was recognized between the crystal grains. <Example 3> Sm having a purity of 99.9%, Fe having a purity of 99.9%, Co having a purity of 99.9%, and I having a purity of 99.9%.
n is melted and mixed in a high-frequency melting furnace in an argon gas atmosphere, and further annealed in an argon atmosphere at 980 ° C. for 1 hour and then at 900 ° C. for 96 hours to obtain S.
An alloy having a composition of m _12.8 Fe _60.8 Co _20.3 In _6.1 was prepared.

Thereafter, in the same manner as in Example 1, the average particle size is 15
A coarse powder of μm was obtained, and an Sm—Fe—Co—In—N powder having the composition shown in Table 1 and an average particle size of 7 μm was obtained. The intrinsic coercive force of the molded body made of 7 μm powder was 9.0 kOe and the residual magnetic flux density was 9.2 kG. As a result of analysis by an X-ray diffraction method, this material was a polycrystal composed mainly of rhombohedral crystals.

As a result of analysis by SEM and TEM photographs, the average distance between crystal grains was 0.07 μm, and a phase mainly composed of In was recognized between crystal grains. <Example 4> Sm with a purity of 99.9%, Fe with a purity of 99.9%, and In with a purity of 99.9% were dissolved and mixed in the same manner as in Example 1 to form an Sm-Fe-In alloy. Obtained.

This alloy was charged into a quartz nozzle and subjected to high-frequency melting under an argon gas atmosphere, and then the melt was rotated at a rotation speed of 1000 rpm to have a diameter of 25 cm and a width of 2.
A flaky sample was prepared by dropping it onto a copper roll of cm. Furthermore, this sample was placed in an argon atmosphere at 1
An alloy of Sm _12.8 Fe _81.0 In _6.2 composition was prepared by annealing at 000 ° C. for 15 minutes and then at 750 ° C. for 3 hours.

This flaky sample was nitrided, annealed and pulverized in the same manner as in Example 1 to give an average particle size of about 15
A coarse powder of μm and a powder having an average particle size of about 7 μm were obtained. Table 1 also shows the composition of the obtained Sm-Fe-In-N-based powder and the evaluation result of the oxidation resistance performance. The intrinsic coercive force of the Sm-Fe-In-N-based powder compact pulverized to 7 μm was 10.5 kOe, and the residual magnetic flux density was 7.0 kG. As a result of analysis by an X-ray diffraction method, this material was a polycrystal composed mainly of rhombohedral crystals.

As a result of analysis by SEM and TEM photographs, the average distance between crystal grains was 0.03 μm, and a phase mainly composed of In was recognized between crystal grains. <Comparative Example 1> Sm-Fe-N-based powder having the composition shown in Table 1 was obtained in the same manner as in Example 1 except that Cu was not added. Table 1 also shows the evaluation results of the oxidation resistance of the obtained powder.

The intrinsic coercive force of the Sm-Fe-N-based powder compact pulverized to 7 μm was 2.7 kOe and the residual magnetic flux density was 8.2 kG. The above results are also shown in Table 1 below.

[0057]

[Table 1]

From the results shown in Table 1, in Examples 1 to 4, the retention rate of the intrinsic coercive force was as high as 90% or more, and the weight change rate was 0.0.
It was as small as 4-0.07% by weight. On the other hand, in Comparative Example 1, the intrinsic coercive force retention rate was as low as 64%, and the weight change rate was as large as 0.26% by weight. <Comparative Example 2> Sm-F having an average particle size of 7 μm obtained in Comparative Example 1
The eN powder was further pulverized to 2 μm. Retention rate of intrinsic coercive force of the obtained fine powder (oxidation resistance-1)
Is 53%, and the intrinsic coercive force of the formed body is 9.5.
The kOe and the residual magnetic flux density were 7.6 kG. <Comparative Example 3> Sm obtained in Example 2 having a particle size of about 7 μm
A powder having a composition of _10.6 Fe _67.3 In _5.1 N _15.2 H _0.5 O _1.3 was magnetically molded under the conditions of ² ton / cm ² and 15 kOe, and then heat-treated under an argon atmosphere at 1100 ° C. for 1 hour. The intrinsic coercive force of the molded body after quenching was 0.1 kOe or less. This molded body is again about 7
The intrinsic coercive force of the powder pulverized to μm was 0.1 kOe or less.

As a result of analyzing the crystal structure of this material by X-ray diffraction, diffraction lines mainly corresponding to α-iron and iron nitride were detected.

[0060]

As described above, according to claim 1, the composition of each component element in the R-Fe-MN magnetic material is specified, and the polycrystalline crystal that forms the main phase of the alloy. By specifying the structure as a rhombohedral crystal or a hexagonal crystal containing R, Fe, and N as the main components, high magnetic characteristics can be imparted to the R-Fe-MN magnetic material.

Further, the average distance between crystal grains in this polycrystal is 0.01 to 3 μm, and the microstructure in which the phase mainly composed of the M component is present between the crystal grains is used to prevent oxidation. The sex can be made extremely high. As a result, a rare earth element that has both high magnetic properties and excellent oxidation resistance
An Fe-M-N based magnetic material can be provided.

According to the second aspect, it is possible to obtain a magnetic material in which the Curie point and the magnetization are increased and the oxidation resistance is further improved. According to claim 3, the main phase is a rhombohedral or hexagonal polycrystal containing R and Fe as main components, and
An average distance between crystal grains is 0.01 to 3 μm, and an R—Fe—M-based alloy having a microstructure in which a phase mainly composed of the M component is present between crystal grains is prepared by using nitrogen gas and ammonia. 200 to under an atmosphere containing at least one of the gases
By nitriding under the temperature condition of 650 ° C, rare earth-Fe-M- having both high magnetic properties and excellent oxidation resistance.
An N-based magnetic material is obtained.

Claims (3)

[Claims] 1. A substance represented by the general formula R _w Fe _x M _y N _z , wherein R is at least one element selected from rare earth elements including Y, and M is selected from Cu and In. W, x, y, and z are at least one element, and w, x, y, and z represent the atomic percentage of each component element and simultaneously satisfy the following formulas (1) to (4).) 3 ≦ w ≦ 20 (1) 25 ≦ x ≦ 93.95 (2) 0.05 ≦ y ≦ 50 (3) 3 ≦ z ≦ 30 (4) A rhombohedron whose main phase contains R, Fe, and N as the main components. It is a polycrystal of hexagonal crystal or hexagonal crystal and has a microstructure in which the average distance between crystal grains is 0.01 to 3 μm and the phase mainly composed of the M component is present between crystal grains. Characteristic magnetic material. 2. 0.01 to 50 atomic% of the Fe component is C
The magnetic material according to claim 1, which is substituted with o. 3. The general formula R _{w / (100-z)} Fe _{x / (100-z)} M
_{y / (100-z)} (wherein R is at least one element selected from rare earth elements including Y, M is Cu and I
at least one element selected from n, w, x,
y represents the atomic percentage of each component element, z represents the content [atomic percentage] of N added later, and w, x, y, z
Satisfy the following expressions (1) to (4) at the same time. ) 3 ≦ w ≦ 20 (1) 25 ≦ x ≦ 93.95 (2) 0.05 ≦ y ≦ 50 (3) 3 ≦ z ≦ 30 (4) The main phase is R And a rhombohedral or hexagonal polycrystal containing Fe as a main component, an average distance between crystal grains of 0.01 to 3 μm, and a phase mainly containing the M component exists between crystal grains. R-Fe-M having a fine structure
A method for producing a magnetic material, comprising nitriding a system alloy under a temperature condition of 200 to 650 ° C. in an atmosphere containing at least one of nitrogen gas and ammonia gas.