JPH10340806A - Rare earth-iron magnetic material and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nanocomposite magnet, whose practical use is expected and the manufacture by providing a hard magnetic phase composed of R(TM,M)12 Nx phase (x)=0.5-2.0} and an extremely fine soft magnetic phase composed of Fe and/or FeCo. SOLUTION: This material is constituted of a hard magnetic phase provided with a composition of R (R is one or two or more kinds of rare earth elements including Y) for 2-10 atomic %, M (M is one or two or more kinds of V, Ti and Mo) for 1-18 atomic % and RM (TM is Fe or Fe and Co) and unavoidable impurities for a remaining part indicated by R(TM,M)12 Nx (x)=0.5-2.0} and the soft magnetic phase composed of Fe and/or Fe and Co, for which an average crystal grain size is 0.1-70 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rare earth-iron magnet material useful as, for example, a bonded magnet and a method for producing the same.

[0002]

2. Description of the Related Art In order to reduce the size and weight of electronic devices, there is a demand for higher performance of bonded magnet materials. At present, nanocomposite magnets that combine a hard magnetic phase and a soft magnetic phase are expected as high-performance materials of magnet powder to be mixed with a bonded magnet. The coercive force of the nanocomposite magnet is generated by the magnetization of the hard magnetic phase fixing the magnetization of the soft magnetic phase by exchange coupling and preventing the magnetization reversal of the soft magnetic phase. In order to make this mechanism work effectively and obtain sufficient coercive force as a magnet material,
It is considered necessary that the size (particle size) of each phase that plays a role in magnet properties is a nano-level size. For the hard magnetic phase of the Nd ₂ Fe ₁₄ B type, see JP-A-8-162312, J. Appl.
hys. 73,6488 (1993), J. Appl. Phys. 76, 7065 (1
994). For Sm ₂ Fe ₁₇ N _x system, JP-A-6-251918, SmFe ₇
The N _x system Hei 8-316018, there is JP-A-6-342706.

[0003]

The nanocomposite magnet can be made into a magnet in a composition range in which the content of expensive rare earth elements is small, and has the advantage that the material cost can be kept lower than conventional rare earth-iron magnets. . However, Nd ₂ Fe ₁₄ B system,
Subjecting the Sm ₂ Fe ₁₇ N _x system or SmFe ₇ N _x less expensive possible ThMn ₁₂ type rare earth nitride phase to less raw material cost the content of the rare earth element than the system in practical use in the nanocomposite magnet according to a hard magnetic phase No excellent magnet properties have been found to be obtained. Therefore, an object of the present invention is to provide an image processing apparatus comprising:
_A hard magnetic phase of ₁₂ N _x (x = 0.5 to 2.0);
An object of the present invention is to provide a nanocomposite magnet having excellent magnet properties that can be put to practical use by including a very fine soft magnetic phase made of e and / or FeCo, and a method for producing the same.

[0004]

Means for Solving the Problems The present inventors have proposed a rare earth element.
In producing an iron-based magnet material, for example, it has been found that the above-described subject can be achieved when a super-quenching method described later, which is excellent in productivity, is employed and a characteristic microstructure is obtained. The details are described below. The rare earth-iron magnet material of the present invention can be obtained, for example, as follows. R (R is one or more of rare earth elements including Y) is 2 to 10 atomic%, and M (M is one or more of Ti, V, and Mo) is 1 to 18 atomic%. Atomic% (preferably 2 to 14 atomic%),
The remainder having a composition of TM (TM is Fe or Fe and Co) and inevitable impurities is melted by, for example, arc melting. Then, ultra-quenched by a liquid quenching method, the obtained ribbon is mechanically pulverized into a powder of several tens of μm, heat treatment for crystallization is performed, and then the rare earth-iron magnet material of the present invention is subjected to nitriding treatment. A powder is obtained. The super-quenching means is not limited, but the single-roll method is preferable in terms of productivity and stability. The roll peripheral speed is desirably 30 m / sec or more in order to obtain a fine crystalline phase after the subsequent nitriding treatment. In the present invention, after preparing a master alloy ingot by arc melting, a homogenization treatment is performed in which the master alloy ingot is kept in an Ar gas atmosphere or in a vacuum at 1000 to 1200 ° C. for 0.5 to 50 hours, followed by homogenization. It is preferable to perform a mechanical pulverization, a heat treatment for crystallization, and a nitriding treatment in this order after ultra-quenching the melt of the master alloy thus formed. Under these manufacturing conditions, a magnet powder having a target composition can be obtained with high accuracy, and existing melting equipment and ultra-quenching equipment can be used, which is highly practical. Heat treatment of the ribbon powder in a non-oxidizing atmosphere such as Ar gas or vacuum from 600 ° C to 1100 ° C
By performing at temperature, a collection of fine crystal grains of ThMn ₁₂ structure. When the heat treatment temperature is less than 600 ° C, Th
Since no Mn _12- type crystal phase is generated, no coercive force is exerted even after nitriding. If the temperature exceeds 1100 ° C., the deterioration of the squareness on the demagnetization curve and the decrease of the coercive force, which are presumed to be due to the coarsening of crystal grains, after the nitriding treatment in the later step become remarkable. After the heat treatment, a nitride phase having a ThMn ₁₂ structure is obtained by performing a nitriding treatment in a temperature range of 300 ° C. to 650 ° C., for example, in a mixed gas of N ₂ or NH ₃ + H ₂ . This nitride phase becomes a hard magnetic phase. To obtain a high coercive force in a state where soft magnetic phases such as Fe and / or FeCo are mixed, Fe
And / or the average crystal grain size of the soft magnetic phase composed of the FeCo phase is 0.1 to 70 nm, preferably 0.1 to 30 nm.
It is good to do. If the average crystal grain size exceeds 70 nm, the squareness and coercive force are significantly reduced. Average grain size is 0.1
If it is less than nm, the soft magnetic phase may substantially disappear after the heat treatment or nitriding treatment. In addition,
After the nitriding treatment, an amorphous phase may be mixed in some cases, but this is included in the present invention. The crystal grain size can be controlled by appropriately adjusting the composition, heat treatment conditions for crystallization, and the like, in addition to the super-quenching speed (roll peripheral speed).
If the nitriding temperature is lower than 300 ° C., nitrogen hardly diffuses into the alloy particles after the heat treatment, so that the formation of a nitride phase is insufficient and a high coercive force is not exhibited. If the temperature exceeds 650 ° C., the coercive force decreases significantly. The magnetizing behavior of the rare earth-iron based alloy magnet powder of the present invention is a hard magnetic phase single phase type, and is a so-called nanocomposite magnet.

Next, a method of calculating the average crystal grain size in the present invention will be described. In a cross-sectional image of the structure of the magnet material of the present invention obtained by a transmission electron microscope, the number (n) of crystal grains included in an optional region is set to n> 40, and the number of crystal grains included in the optional region is n> 40. When the total cross-sectional area is A, the diameter of a circle having a cross-sectional area corresponding to the average cross-sectional area per crystal grain (A / n) is defined as the average crystal grain size D.
That is, from π (D / 2) ² = A / n, it is defined as D = 2 (A / (nπ)) ^1/2 .

Next, the reasons for limiting the composition will be described. R is 2-1
The content of 0 atomic% is preferable because a fine composite structure in which a hard magnetic phase and a very fine soft magnetic phase composed of Fe and / or FeCo are mixed can be stably obtained. If R is less than 2 atomic%, the volume ratio of the hard magnetic phase becomes extremely small, and a sufficient square shape and coercive force cannot be obtained. If R exceeds 10 atomic%, a soft magnetic phase may not be generated, and it is difficult to reliably realize the present invention. As the rare earth element R,
Y, La, Ce, Pr, Nd, Sm, Gd, Tb, D
y, Ho, Er, Tm, and Lu are included. Furthermore, P
It is more preferred that r and / or Nd contain at least 50 atomic% of R, and all of R is Pr and / or Nd
Is particularly preferred. The reason that 50 atomic% or more of R is Nd and / or Pr is that when Nd and / or Pr is less than 50 atomic%, sufficient remanent magnetization cannot be obtained, and the use of Pr and / or Nd causes This is because raw material costs can be reduced. M (one or more of V, Ti, and Mo) in order to provide a practically usable residual magnetic flux density (Br), square shape, and coercive force (Hc)
Is preferably 1 to 18 atomic%. 18 atomic%
Is exceeded, the saturation magnetization and Br decrease significantly. When M is less than 1 atomic%, the magnet structure of the present invention becomes unstable. In addition,
In the composition of the magnet material of the present invention in which a hard magnetic phase and a soft magnetic phase are mixed, a soft magnetic phase mainly composed of Fe and M elements and / or a soft magnetic phase mainly composed of Fe, Co and M elements Is the hard magnetic phase, Fe and / or
Alternatively, it may be mixed with a soft magnetic phase made of FeCo, but is of course included in the present invention. The hard magnetic phase of the present invention has an average crystal grain size of 2 to 500.
nm, which is preferable for obtaining a high coercive force as isotropic magnet powder.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples, but the present invention is not limited by the following. (Examples 1 to 5, Comparative Examples 1 to 4)
After preparing a mother alloy ingot (corresponding to Examples 1 to 5 and Comparative Examples 1 to 4 in Table 1) having a composition of Nd _y Fe _bal V _{11.0 in} atomic%, in a Ar gas atmosphere for homogenization treatment. 105
It was kept at 0 ° C. × 5 hours and cooled. Next, the liquid was rapidly quenched by a liquid quenching single roll method at a roll peripheral speed of 50 m / sec to produce a super quenched ribbon. The composition of each of the obtained ribbons was the same as that of the mother alloy used. Next, each of the ribbons was mechanically pulverized into a powder having a size of 75 μm or less.
Heat treatment was performed for a period of one minute to obtain fine crystalline powder. Thereafter, a nitriding treatment was performed at 500 ° C. for 5 hours in a nitrogen gas at 1 atm. Table 1 shows typical examples of the average crystal grain size (D _Fe ) of the crystal phase and the soft magnetic phase (Fe) of each of the obtained magnet powders, and the magnetic properties. The magnetic characteristics were as follows. An appropriate amount of each magnet powder was put in a copper capsule, and solid paraffin wax was covered thereon, followed by heating and sealing. Place this sample between the pole pieces of the BH tracer and
It was magnetized by applying the magnetic field e. These are VS
M (Vibration sample type magnetometer manufactured by Toei Industry Co., Ltd .: VSM-3
And applying a magnetic field of 14 kOe at 20 ° C. to draw a demagnetization curve. From the obtained data (emu / g) corresponding to Br, the data (emu / g) × (4π / 1
0 ⁴ ) × (theoretical density 7.7 g / cm ³ ) = Br (T), and the coercive force (Hc) and the maximum energy product ((BH) ma
x) was evaluated. From Table 1 and the related examination results, the Nd content (y) of the rare-earth-iron-based magnet powder is y =
When the content is 2 to 10 atomic%, Nd (F
e, V) A hard magnetic phase having a composition of ₁₂ N _x (x = 1.0 to 1.5) and an average crystal grain size (D _Fe ) of 0.1 to 70 nm.
It is suggested that a magnet powder composed of Fe (soft magnetic phase) is formed and can be put to practical use. In Table 1, the magnetic properties of Comparative Example 1 including only the soft magnetic phase are very low. Further, the magnet powder of the present invention has magnetic properties equal to or higher than those of Comparative Examples 2 to 4 including only the hard magnetic phase,
Each magnetization curve was a hard magnetic phase single phase type. Therefore, the magnet powder of the present invention suggested that Nd (Fe, V) ₁₂ N _X (X = 1.0 to 1.5) and Fe were exchange-coupled to form a nanocomposite magnet.

[0008]

[Table 1]

(Examples 6 to 11 and Comparative Example 5) A _master alloy ingot having a composition of Nd _5.5 Fe _bal V _11.0 in atomic% was prepared by arc melting, and then 1050 in an Ar gas atmosphere for homogenization treatment. A heat treatment of keeping at 5 ° C. × 5 hours was performed. Next, the homogenized master alloy was ultra-quenched by a liquid quenching single roll method at a roll peripheral speed of 50 m / sec to obtain a ribbon.
The composition of the obtained ribbon was similar to that of the mother alloy. Next, after the ribbon was mechanically pulverized into powder having a size of 75 μm or less, 500 to 1100 ° C. × 10 4 in an Ar gas atmosphere to check the correlation between the degree of crystallization of the ribbon and the magnetic properties of the final magnet powder.
Heat treatment for a minute. Thereafter, a nitriding treatment was performed under a condition of 500 ° C. × 5 hours in a nitrogen gas atmosphere at 1 atm. Table 2 shows typical examples of the crystal phase, D _Fe of each of the obtained powders, and the magnetic properties evaluated in the same manner as described above. From Table 2 and the like, when the heat treatment temperature is 600 to 1100 ° C., Nd (Fe, V) ₁₂ N _X (X
= 1.0-1.5) and an average crystal grain size of 0.1.
It can be seen that a magnetic powder having high magnetic properties in which Fe in the range of 1 to 70 nm is exchange-coupled can be obtained. However, in the case of Comparative Example 5, the heat treatment temperature was too low, and almost no ThMn ₁₂ type crystal phase was generated. For this reason, the coercive force was very small even after the subsequent nitriding treatment.

[0010]

[Table 2]

(Examples 12 and 13) A _master alloy ingot having a composition of Nd _5.5 Fe _bal M _11.0 (M is Ti or Mo) in atomic% by arc melting was produced by arc melting, and then 1050 for homogenization treatment. Heat treatment was performed in an Ar gas atmosphere at 5 ° C. for 5 hours. Next, each homogenized master alloy was ultra-quenched by a liquid quenching single roll method at a roll peripheral speed of 50 m / sec to produce a ribbon. The compositions of the two obtained ribbons were similar to the mother alloy composition. Next, each of the ribbons was pulverized into powder having a size of 75 μm or less, and then heat-treated at 850 ° C. for 10 minutes in an Ar gas atmosphere for crystallization. After that, 50 atmospheres in 1 atmosphere of nitrogen gas
A nitriding treatment was performed at 0 ° C. × 5 hours. Table 3 shows the crystal phases, D _Fe, and magnetic properties of the two types of nitride magnet powders obtained, which were evaluated in the same manner as described above. As shown in Table 3, the case where the crystal phase after nitriding is composed of Fe and Nd (Fe, Ti) ₁₂ N _X (x = 1.0 to 1.5) having an average crystal grain size of 0.1 to 70 nm. ,
Or, if consisting of Fe and _{Nd (Fe, Mo) 12 N} X and (x = 1.0 to 1.5), it is possible to form a magnetic powder of the present invention. Further, W, Zr, M are used instead of V, Ti, and Mo as M elements.
It is expected that the magnet material of the present invention can be formed also when one or more of n, Ga, Cr, Nb, Hf, Ta, and Al are used. That is, when the crystal phase after nitriding is composed of Fe and Nd (Fe, W) ₁₂ N _X (x = 0.5 to 2.0),
Or, Fe and Nd (Fe, Zr) ₁₂ when consisting N _X and (x = 0.5~2.0), or, Fe and Nd (Fe, Mn) if composed of a _{12 N X (x = 0.5~2.0)} , Alternatively, Fe and Nd (Fe, Ga) ₁₂ N _X (x = 0.5 to 2.
0) or Fe and Nd (Fe, Cr) ₁₂ N _X (x = 0.
5 to 2.0), or Fe and Nd (Fe, Nb) ₁₂ N _X
(X = 0.5-2.0), or Fe and Nd (Fe, H
f) ₁₂ when consisting N _X and (x = 0.5~2.0), or, Fe and Nd
(Fe, Ta) ₁₂ N _X (x = 0.5-2.0) or F
e and Nd (Fe, Al) ₁₂ N _X (x = 0.5 to 2.0).

[0012]

[Table 3]

(Examples 14 to 17) Examples in which the substitution amount of Co is set to 20 atom% or less in order to suppress the material cost will be described. First, Nd _5.5 Fe _{bal in} atomic% by arc melting
A total of four types of mother alloys having a composition of Co _Z V _11.0 (Z = 2.0 to 8.0%) were produced. Next, 1050 ° C. × 5 for homogenization
It was kept in an Ar gas atmosphere under the condition of time and cooled. Next, each of the homogenized master alloys was ultra-quenched by the liquid quenching single roll method under the condition of a roll peripheral speed of 50 m / sec to be thinned.
The composition of each of the obtained four ribbons was the same as the composition of the mother alloy. Next, each of the obtained ribbons was pulverized into powder having a size of 75 μm or less, and then heat-treated at 850 ° C. for 10 minutes in an Ar gas atmosphere. After that, 500 ° C x 1 atmosphere of nitrogen gas
The nitriding treatment was performed for 5 hours. The crystal phase of each of the obtained magnet powders, the average crystal grain size (D _FeCo ) of the FeCo soft magnetic phase,
Table 4 shows the magnetic properties evaluated in the same manner as above. Table 4
For example, when the Co substitution amount is 20 atomic% or less, the crystal phase after nitriding has a soft magnetic phase FeCo phase having an average crystal grain size of 0.1 to 70 nm and a hard magnetic phase Nd (Fe, Co, V). ) ₁₂ N
_A magnet powder consisting of _X (x = 1.0 to 1.5) was obtained, showing good magnet properties.

[0014]

[Table 4]

(Example 18) Nd _5.0 Fe _bal V in atomic%
75 μm in the same manner as in Example 1 except that the composition was _11.0.
m or less was prepared. Next, heat treatment was performed at 850 ° C. for 10 minutes in an Ar gas atmosphere to perform crystallization. Subsequently, 500 ° C. × 5 in nitrogen gas at 0.1 to 10 atm or a mixed gas of ammonia and hydrogen.
Perform nitriding treatment with holding for Nd (Fe, V) ₁₂ N _X (x = 0.1 ~ 2.
4) Hard magnetic phase and the average crystal grain size is in the range of 0.1-70nm
A magnet powder composed of an Fe phase (soft magnetic phase) was obtained. FIG.
The correlation between x of the obtained magnet powder and Hc evaluated in the same manner as above was plotted. From FIG. 1, x = 0.5 to 2.0
Thus, a high coercive force (Hc) expected to be put to practical use can be obtained.

[0016]

According to the present invention, it is possible to provide a rare earth-iron based magnet material excellent in cost performance and a method for producing the same. For example, mass production is possible by applying a super-quenching method, and the usefulness as a raw material magnetic powder of an isotropic rare earth bonded magnet is greatly expected.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a correlation between x and Hc in the present invention.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01F 1/053 H01F 1/04 H

Claims (2)

[Claims] 1. R (R is one or more of rare earth elements including Y) is 2 to 10 atomic%, and M (M is V,
One or two or more of Ti and Mo) has a composition of 1 to 18 atomic%, and the balance is TM (TM is Fe or Fe and Co) and unavoidable impurities, and R (TM, M ) ₁₂ N _x (x = 0.5-2.
0) and an average crystal grain size of 0.1
A rare-earth-iron-based magnet material substantially constituted by Fe and / or a soft magnetic phase composed of Fe and Co of up to 70 nm. 2. R (R is one or more of rare earth elements including Y) is 2 to 10 atomic%, and M (M is V,
One or two or more of Ti and Mo) have a composition of 1 to 18 atomic%, and the balance is TM (TM is Fe or Fe and Co) and unavoidable impurities.
(M, M) ₁₂ N _x (x = 0.5 to 2.0), a hard magnetic phase, and a soft magnetic phase composed of Fe and / or Fe and Co having an average crystal grain size of 0.1 to 70 nm. The method for producing a rare earth-iron magnet material substantially composed of: a rare earth-iron magnet material, comprising: after preparing a super-quenched alloy ribbon having the above composition, sequentially performing pulverization, heat treatment, and nitriding treatment. Manufacturing method of magnet material.