JP3298219B2 - Rare earth-Fe-Co-Al-V-Ga-B based sintered magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, -Fe- rare earth has excellent energy product and heat resistance and heat treatability Co
-Al-V-Ga- B based sintered magnet.

[0002]

2. Description of the Related Art Nd-Fe-B sintered magnets are made of SmCo.
_Since it has a higher energy product (BH) max than a _5- based sintered magnet or a Sm ₂ Co _17- based sintered magnet, it has been used for various applications. However,
Nd-Fe-B based sintered magnets are inferior in thermal stability to these Sm-Co based sintered magnets, and various attempts have been made to increase the thermal stability. The JP 64-7503 Publication as an example, the general formula as a good permanent magnet thermal _{stability: R (Fe 1-xyz Co} x B y Ga z) A ( Here, R is selected from rare earth elements 0 ≦ x ≦ 0.7, 0.02 ≦ y ≦ 0.3, 0.001
≦ z ≦ 0.15,4.0 a ≦ A ≦ 7.5), _{and, R (Fe 1-xyz Co} x B y Ga z M u) A ( provided that at least R is selected from rare earth elements M is one selected from Nb, W, V, Ta and Mo
A kind or two or more kinds of elements, 0 ≦ x ≦ 0.7, 0.0
2 ≦ y ≦ 0.3, 0.001 ≦ z ≦ 0.15, u ≦ 0.1,
4.0 ≦ A ≦ 7.5. ) Are disclosed.

[0003]

Recently, there has been a demand for further downsizing of a device using a permanent magnet, and accordingly, a permanent magnet having excellent thermal stability and a high energy product has been required. Appearance is desired. JP-A-64-
The permanent magnet described in No. 7503 improves the coercive force iHc by adding Ga and realizes excellent thermal stability, but cannot satisfy the above requirement with respect to the energy product. That is, in practice, the coercive force iHc is 12K
Although it is required to have Oe or more, the energy product (BH) max of the magnet having this level of coercive force is 40 M
GOe or less. Therefore, the present invention provides the above-mentioned rare earth (Nd
And Dy, optionally containing Pr) -Fe-Co-Al
-V-Ga-B based alloy composition is selected and contained Ga
Is concentrated to a rare earth rich phase over a predetermined amount,
Rare earth having 42MGOe or more high maximum energy product (BH) ma x, coercive force iHc practicable above 12 kOe, and excellent heat treatability at room temperature -Fe-
It is an object to provide a Co-Al-V-Ga- B based sintered magnet.

[0004]

Means for Solving the Problems The present inventors have found that the composition and Mi of Nd-Fe-B magnets in order to solve the problem
The following findings were obtained when the black tissue was examined in detail. (1) If the Nd content is reduced, the energy product (BH)
Although the max increases, the coercive force iHc decreases. (2) Coercive force iHc by reducing Nd content
It is effective to add Ga in order to compensate for the decrease in the coercive force iHc, but the effect of improving the coercive force iHc of Ga saturates with a certain amount of addition, and the decrease in the coercive force iHc cannot be sufficiently compensated. (3) To improve the coercive force iHc that cannot be compensated by the addition of Ga, D
The addition of y is valid, by adding in a range not less decreased residual magnetic flux density Br, 42M at room temperature
GOe higher than energy product (BH) max, and also have a coercive force iHc of withstanding more practical 12KOe
The can be obtained. The important thing here is that the good magnetic
Characteristic is that the contained Ga is more than a predetermined amount in the rare earth rich phase
Is realized when it becomes a concentrated microstructure.
You. The present invention has been made based on the above findings,
Substantially Nd and Dy or Nd, Dy and Pr
Ranaru rare earth element 28~32wt% (where Dy is 0.
4 to 3 wt%), Co 6 wt% or less (excluding 0) , A
l0.5 wt % or less (excluding 0) , B0.9 to 1.3w
t%, V 0.05-2.0 wt%, Ga 0.02-0.5 w
t%, oxygen 500Ppm～5000ppm, and a balance of Fe and unavoidable impurities, coercivity iH at room temperature
c is 12 kOe or more, maximum energy product (BH) max
Rare earth but Ri der more than 42MGOe, which is excellent in heat treatment of -
A Fe- Co-Al-V-Ga- B based sintered magnet ,
The average Ga content in the rare earth rich phase is equal to the total Ga content of the sintered magnet.
Rare earth- Fe characterized by being at least twice the content
-Co-Al-V-Ga- B based sintered magnet.

The reasons for limiting the components of the sintered magnet of the present invention are described below. Nd and Dy or Nd, Dy and Pr
In the present invention, Nd and Dy or Nd, Dy and
Pr is in the range of 28 to 32 wt% (however, Dy is 0.4 to
3 wt%). As will be described later in the examples, the smaller the amount of Nd is, the more effective it is to improve (BH) max and the residual magnetic flux density Br, but lower the coercive force iHc. In the present invention, Dy is added to improve the coercive force iHc. This Dy increases the Curie point Tc and increases the anisotropic magnetic field (HA), thereby contributing to the improvement of the coercive force iHc. However, when the content increases, the residual magnetic flux density Br decreases and the maximum energy product (BH) max also decreases. Therefore, the content of Dy is in the range of 0.4 to 3.0 wt%. The most desirable amount of Dy is 0.7-1.5w
t%. When the content of Nd decreases, it is difficult to expect an increase in (BH) max due to generation of α-Fe in the ingot, while when it increases, the (BH) max decreases due to an increase in the Nd-rich phase. Nd
And Dy , or the total amount of Nd, Dy and Pr is 2
8 to 32 wt%. Note that a part of Nd can be replaced with another rare earth element (excluding Dy and Pr ).

In the present invention, Co is the residual magnetic flux density Br
In addition to improving the corrosion resistance of the magnetic alloy itself without substantially reducing the corrosion resistance, there is an effect of improving the corrosion resistance by improving the adhesion of Ni plating, which is a corrosion-resistant coating. Further, there is also an effect of increasing the Curie point Tc by replacing Fe in the main phase (Nd ₂ Fe ₁₄ B) with Co. However, when the substitution amount of Co is increased, coarse crystal grains are generated due to abnormal grain growth during sintering, and the coercive force iHc and the squareness of the hysteresis curve are reduced.
Therefore, the Co content is set to 6.0 wt% or less.

In the present invention, Co and Al are added in appropriate amounts.
The allowable range of the secondary heat treatment temperature
Can be. Attachment of Co only to the rare earth -Fe-B based sintered magnet
If you pressure, variation of the magnetic characteristics against the variations in the secondary heat treatment temperature is large Kunar. (Not including 0) 0.5 wt% or less Al with containing a predetermined amount of Co-containing Accordingly, the
Even if the secondary heat treatment temperature fluctuates, the fluctuation in magnetic properties is suppressed to a small extent
As a result , products of stable quality can be produced.
If the Al content exceeds 0.5 wt% , the decrease in the residual magnetic flux density Br becomes remarkable. Therefore, the content of Al is 0.5
% or less ( not including 0 ) is preferred .

[0008] B is an essential element in the rare earth- Fe-B based magnet. If B is less than 0.9 wt%, a high coercive force cannot be obtained, while if it exceeds 1.3 wt%, the B-rich nonmagnetic phase increases and the residual magnetic flux density Br decreases.
Therefore, the content is set to 0.9 to 1.3 wt%. The preferred B content is 0.95 to 1.1 wt%.

[0009] Ga has the effect of improving the coercive force iHc without substantially reducing the residual magnetic flux density Br. If the Ga content is less than 0.02 wt%, the effect of improving the coercive force iHc is not sufficient. If the Ga content exceeds 0.5 wt%, the effect of improving the coercive force iHc is saturated and the residual magnetic flux density B
r decreases, and a desired high energy product cannot be obtained. Therefore, the Ga content is set to 0.02 to 0.5 wt%. A desirable range of Ga is 0.03 to 0.2 wt%. Ga exhibits its effect by being present in the Nd-rich Nd- rich phase in the magnet body. In particular, when the average Ga amount in the Nd- rich phase is twice or more the total Ga addition amount, the effect is exhibited. Remarkable. The amount of Ga in the Nd- rich phase depends on the sintering conditions,
It varies depending on the heat treatment conditions.

[0010] The sintered magnet of the present invention has a content of 0.1% in addition to the above components.
It contains 0.5 to 2.0 wt% V. V is periodic table number V
Addition of a metal element belonging to group a has an effect of suppressing the crystal grains from becoming coarse during sintering. By this effect, the coercive force iHc is improved, and the squareness of the hysteresis curve is improved. In addition, Nd-F with good magnetizability
The eB-based magnet has excellent heat resistance, but when the crystal grains of the sintered body are made fine, the magnetization is improved. Therefore, V is an element effective for improving heat resistance. V content is 0.05wt
%, The effect of suppressing coarse grains is insufficient.
On the other hand, when the content of V exceeds 2.0 wt%, V
Alternatively, a large amount of nonmagnetic boride of V-Fe is generated, and the residual magnetic flux density Br and the Curie point Tc are remarkably reduced, which is not preferable. Therefore, the content of V is set to 0.05 to 2.0 wt%. Preferably, it is 0.1 to 1.0 wt%.

In the present invention, the oxygen content is set to 500 p
pm to 5000 ppm. If the amount of oxygen is less than 500 ppm, the magnet powder and its compact are liable to catch fire, which is dangerous for industrial production. On the other hand, when it is more than 5000 ppm, oxygen is Nd, Dy or Nd, Dy and Pr.
N that effectively acts on magnetism by forming oxides with
The amount of d, Dy or Nd, Dy and Pr is reduced, making it difficult to obtain a magnet with high coercive force and high energy product.

The sintered magnet of the present invention can be manufactured as follows. That is, an ingot having a certain component composition is produced by vacuum melting, and then the ingot is roughly pulverized to obtain a coarse powder having a particle size of about 500 μm. The coarse powder is finely pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder having an average particle size of 3.0 to 6.0 μm (FSSS). Next, this fine powder was press-molded in a magnetic field under the conditions of an orientation magnetic field of 15 kOe and a molding pressure of 1.5 ton / cm ² ,
Sintering is performed in a temperature range of 000 to 1150 ° C.

The heat treatment after sintering can be performed as follows. The sintered body obtained by sintering the compact is once cooled to room temperature. The cooling rate after sintering depends on the coercive force i of the final product.
Has little effect on Hc. Then, 800-1000
Heat to a temperature of ° C. and hold for 0.2-5 hours. This is the first heat treatment. Heating temperature less than 800 ° C or 10
If the temperature exceeds 00 ° C., a sufficiently high coercive force cannot be obtained. After the heating and holding, it is cooled to a temperature of from room temperature to 600 ° C. at a cooling rate of 0.3 to 50 ° C./min. When the cooling rate exceeds 50 ° C./min, an equilibrium phase required for aging cannot be obtained, and a sufficiently high coercive force cannot be obtained. On the other hand, a cooling rate of less than 0.3 ° C./minute requires a long time for heat treatment, which is not economical for industrial production. Preferably, a cooling rate of 0.6 to 2.0 ° C / min is selected. The cooling end temperature is desirably room temperature, but may be up to 600 ° C. if the coercive force iHc is somewhat sacrificed, and may be rapidly cooled below that temperature. Preferably, it cools to the temperature of normal temperature-400 degreeC.

The heat treatment is further performed at a temperature of 500 to 650 ° C. for 0.2 to 3 hours. This is a second heat treatment. Although it depends on the composition, a heat treatment at 540 to 640 ° C. is preferably effective. When the heat treatment temperature is lower than 500 ° C. or higher than 650 ° C., the irreversible demagnetization rate decreases even if a high coercive force is obtained. After the heat treatment, cooling is performed at a cooling rate of 0.3 to 400 ° C./min, as in the first heat treatment. Cooling can be performed in water, in silicon oil, in a stream of argon, or the like. When the cooling rate exceeds 400 ° C./min, the sample is cracked by rapid cooling, and an industrially valuable permanent magnet material cannot be obtained. When the temperature is lower than 0.3 ° C./minute,
An unfavorable phase appears in the coercive force iHc during the cooling process.

[0015]

The present invention will be described in more detail with reference to the following examples. (Example 1) Metal Nd, metal Dy, Fe, Co, ferro-B, f
Erro-V and metal Ga were weighed to a predetermined weight and were melted in vacuum to produce an ingot weighing 10 kg. The composition of this ingot was as follows by weight. _{Nd a -Dy b -B 1.04 -V 0.59} -Ga C -Co 0.20 -A
l _0.35 -Fe _bal. (wt%) After crushing this ingot with a hammer, it was further coarsely crushed in an inert gas atmosphere by using a coarse crusher to obtain 500 μm.
A coarse powder having a particle size of not more than m was obtained. The coarse powder was similarly pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder. This fine powder had an average particle size of 4.0 μm (FSSS) and an oxygen content of 5300 ppm. Next, this fine powder was subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 ton.
Press molding in a magnetic field under the condition of n / cm ² , 20 × 20
A molded body of × 15 was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum conditions, and the resulting sintered body was subjected to a first heat treatment at 900 ° C. × 2 hr, and then to 530 ° C.
A second heat treatment was performed at 2 ° C. × 2 hours. The density of the obtained sintered body is 7.55 to 7.58 g / cc, and the oxygen content is 1
It was 100 to 4000 ppm. At room temperature, the magnetic properties of these samples were measured, and the results shown in FIGS. 1, 2 and 3 were obtained. FIG. 1 shows Dy = 1.0 wt%, Ga =
It is the graph which showed the relationship between the amount of Nd and magnetic characteristics as 0.06 wt%. As the Nd amount increases, the coercive force iHc
, But the residual magnetic flux density Br tends to decrease. FIG. 2 is a graph showing the relationship between the amount of Ga and the magnetic characteristics when Dy = 1.0 wt% and Nd = 29 wt%. G
The coercive force iHc increases with an increase in the amount a, but is 0.08.
The effect saturates at about wt%. During this time, the decrease in the residual magnetic flux density Br is slight. FIG. 3 shows Nd
7 is a graph showing the relationship between the Dy amount and the magnetic properties when = 29 wt% and Ga = 0.06 wt%. Although the coercive force iHc increases as the Dy amount increases, the decrease in the residual magnetic flux density Br becomes remarkable, and the maximum energy product (BH) max also deteriorates. As described above, from FIGS. 1 to 3, it is necessary to optimize the amount of Nd and to add an appropriate amount of Dy and Ga in combination to optimize both the maximum product of energy (BH) max and the coercive force iHc. Understand.

Example 2 Metal Nd, metal Dy, Fe, Co, ferro-B, f
Erro-V and metal Ga were weighed to a predetermined weight and were melted in vacuum to produce an ingot weighing 10 kg. The composition of this ingot was as follows by weight. Composition: Nd _29.5 -Dy _1.2 -B _1.03 -V _0.35 -Ga
_0.06 -Co _0.30 -Al _0.33 -Fe _bal. (Wt%) After crushing this ingot with a hammer, it was further coarsely crushed in an inert gas atmosphere by using a coarse crusher to obtain 500 μm _.
A coarse powder having a particle size of not more than m was obtained. The coarse powder was similarly pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder. At this time, by adding a small amount of oxygen to the inert gas, fine powders of various oxygen contents were obtained. The fine powder had an average particle size of 4.0 μm (FSSS). Next, this fine powder was subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 to.
Press molding in a magnetic field under the condition of n / cm ² , 20 × 20
A molded body of × 15 was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum conditions, and the resulting sintered body was subjected to a first heat treatment at 900 ° C. × 2 hr, and then to 530 ° C.
A second heat treatment was performed at 2 ° C. × 2 hours. The density of the obtained sintered body is 7.55 to 7.58 g / cc, and the oxygen content is 1
000-5800 ppm. Room-temperature magnetic properties of these samples were measured. The results are shown in FIG. 4. When the oxygen content exceeds 5000 ppm, the coercive force iHc is significantly reduced, so the oxygen content is set to 1000 to 5000 ppm. FIG. 5 shows that the oxygen content is 5400 ppm and 2000p.
EPMA of Nd and oxygen of two sintered bodies different from pm
(Electron beam microanalyzer) shows the results of line analysis.
In the sintered body containing a large amount of oxygen, most of the peaks of Nd overlap with the peaks of oxygen, and it is considered that a large amount of Nd oxide is formed. On the other hand, in the sintered body having a small oxygen content, the Nd peak and the oxygen peak overlap with each other, but the Nd peak present alone is considerably observed. That is, while the sintered body having a large oxygen content is present as an oxide in which Nd does not contribute to the magnetic properties,
A sintered body having a small oxygen content contains a large amount of Nd which effectively contributes to magnetic properties. In FIG. 5, the circles indicate peaks in which Nd exists independently of oxygen.

(Example 3) Didymium metal (Nd 70 wt% -Pr 30 wt%), metal Dy, Fe, Co, ferro-B, ferro-
V and metal Ga were weighed to a predetermined weight, and were vacuum-dissolved to produce an ingot weighing 10 kg. The composition of this ingot was as follows by weight. Composition: (Nd + Pr) _28.5 -Dy _0.6 -B _1.05 -V _x
-Ga _0.05 -Co _2.25 -Al _0.35 -Fe _bal. (Wt%) After crushing this ingot with a hammer, it was further coarsely crushed in an inert gas atmosphere by using a coarse crusher and 500 µm _.
A coarse powder having a particle size of not more than m was obtained. The coarse powder was similarly pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder. At this time, by adding a small amount of oxygen to the inert gas, fine powders of various oxygen contents were obtained. The fine powder had an average particle size of 4.0 μm (FSSS). Next, this fine powder was subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 to.
Press molding in a magnetic field under the condition of n / cm ² , 20 × 20
A molded body of × 15 was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum conditions, and the resulting sintered body was subjected to a first heat treatment at 900 ° C. × 2 hr, and then to 530 ° C.
A second heat treatment was performed at 2 ° C. × 2 hours. The density of the obtained sintered body was 7.55 to 7.58 g / cc, and the oxygen content was 2
It was 600 to 4400 ppm. With respect to these samples, the room temperature magnetic characteristics and the average particle size were measured, and the results as shown in FIG. 6 were obtained. As shown in FIG. 6, by adding V, crystal grain growth during sintering can be suppressed, and as a result, the average grain size of the sintered body can be reduced. In addition, this effect can be expected to improve the coercive force iHc. Even with a content of 2.0 wt% or more, a decrease in the average particle size cannot be expected so much.
Further, since the reduction of the maximum energy product (BH) max becomes large, the addition of 0.1 to 2.0 wt% is an appropriate amount.

(Embodiment 4) Metal Nd, metal Dy, Fe, Co, ferro-B, f
Erro-V and metal Ga were weighed to a predetermined weight and were melted in vacuum to produce an ingot weighing 10 kg. The composition of this ingot was as follows by weight. Nd _27.5 -Dy _0.8 -B _1.00 -V _0.34 -Ga _0.20 -Co _y -Al _z -Fe _bal. Y = 0 z = 0 y = 1.57 z = 0 y = 1.60 z = 0.35 (wt%) After crushing with a hammer, coarse crushing is performed in an inert gas atmosphere using
A coarse powder having a particle size of not more than μm was obtained. The coarse powder was similarly pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder. This fine powder has an average particle size of 3.8 μm (FSSS).
And the oxygen content was 4200 to 5300 ppm. Next, this fine powder was press-molded in a magnetic field under the conditions of an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 ton / cm ² .
A 30 × 20 × 15 compact was produced. This molded body is subjected to sintering at 1100 ° C. × 2 hours under a substantially vacuum condition,
The obtained sintered body was subjected to a first heat treatment at 900 ° C. × 2 hr, and then to a second heat treatment at 500 to 600 ° C. × 2 hr. The density of the obtained sintered body is 7.56 to 7.59 g / c.
c and the oxygen content was 2100 to 3300 ppm. The magnetic properties at room temperature were measured for these samples, and the results shown in FIG. 7 were obtained. As shown in FIG.
o alone (△) has magnetic properties of Co and A
l The temperature dependency of the second heat treatment is larger than that of the case without (o) . That is, the temperature of the second heat treatment fluctuates.
In this case, the decrease in iHc is remarkable. Next , the composite addition of Co and Al (□) was obtained by adding Co alone.
I for the same second heat treatment temperature as compared to
Hc could be increased and secondary heat treatment temperature fluctuated
It can be seen that the iHc in the case is moderate. in this way
It is useful to add Al and Co in combination.

Next, Ni was added to the magnet having the composition of (Co-free), (Co-added), (Co, Al-added).
After plating, the adhesion was evaluated. Ni plating was performed to a film thickness of 10 μm by electrolytic plating using a Watts bath.
After the plating treatment, the plate was washed with water, dried at 100 ° C. for 5 minutes, and then subjected to a plating adhesion test. The results are as follows, and show that the Co additive has excellent plating adhesion. Material Adhesion strength (Kgf / cm2) (no Co added) 150 (Co added) 660 (Co, Al added) 685

(Embodiment 5) Metal Nd, metal Dy, Fe, Co, ferro-B, f
Erro-V and metal Ga were weighed to a predetermined weight and were melted in vacuum to produce an ingot weighing 10 kg. The composition of this ingot was as follows by weight. _{Nd 28.5 -Dy 0.80 -B 1.20 -V 1.05} -Ga c -Co 0.15 -Al 0.32 -Fe bal. (Wt%) The ingot was crushed by a hammer, further crusher used in an inert gas atmosphere 500μ
A coarse powder having a particle size of not more than m was obtained. The coarse powder was similarly pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder. This fine powder had an average particle size of 4.0 μm (FSSS) and an oxygen content of 4300 ppm. Next, this fine powder was subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 ton.
Press molding in a magnetic field under the condition of n / cm ² , 20 × 20
A molded body of × 15 was produced. This compact was sintered at 1070 ° C. × 3 hrs under substantially vacuum conditions, and the obtained sintered compact was subjected to a first heat treatment at 930 ° C. × 2 hrs, followed by 52 hrs.
A second heat treatment at 0 ° C. × 2 hr was performed. The density of the obtained sintered body was 7.54 to 7.57 g / cc, and the oxygen content was 1000 to 3200 ppm. For these samples, the relationship between the Ga content of the entire sample, the Ga content in the Nd- rich phase and the coercive force iHc was investigated. Table 1 shows the results.

[0021]

[Table 1]

Example 6 Metal Nd, metal Dy, Fe, Co, ferro-B, f
Erro-V and metal Ga were weighed to a predetermined weight and were melted in vacuum to produce an ingot weighing 10 kg. The composition of this ingot was as follows by weight. Nd _28.0 -Dy _1.0 -B _1.03 -V _0.67 -Ga _0.1 -Co _0.21 -Al _0.35 -Fe _bal. (Wt%) After crushing this ingot with a hammer, further using a coarse crusher in an inert gas atmosphere. 500μ
A coarse powder having a particle size of not more than m was obtained. The coarse powder was similarly pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder. This fine powder had an average particle size of 4.0 μm (FSSS) and an oxygen content of 4800 ppm. Next, this fine powder was subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 ton.
Press molding in a magnetic field under the condition of n / cm ² , 20 × 20
A molded body of × 15 was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum conditions, and the resulting sintered body was subjected to a first heat treatment at 900 ° C. × 2 hr, and then to 530 ° C.
A second heat treatment was performed at 2 ° C. × 2 hours. The density of the obtained sintered body is 7.55 to 7.58 g / cc, and the oxygen content is 1
000-3600 ppm. For these samples, the relationship between the average Ga content in the Nd- rich phase and the coercive forces iHc and Hk was investigated. Results are illustrated in Table 2, Nd ripple
When the average Ga content in the h phase is 1.7 times or less of the total Ga content , the coercive force iHc is 11.7 KOe or less and 12 KO
e is not reached.

[0023]

[Table 2]

(Example 7) Metal Nd, metal Dy, Fe, Co, ferro-B, f
Erro-V and metal Ga were weighed to a predetermined weight and were melted in vacuum to produce an ingot weighing 10 kg. The composition of this ingot was as follows by weight. Nd _27.5 -Dy _2.0 -B _{1.1 / 1.4} -V _1.6 -Ga _0.08 -Co _0.22 -Al _0.30 -Fe _bal. (Wt%) After crushing this ingot with a hammer, further use a coarse crusher and inert gas atmosphere. 500μ
A coarse powder having a particle size of not more than m was obtained. The coarse powder was similarly pulverized in an inert gas atmosphere using a jet mill to obtain a fine powder. This fine powder had an average particle size of 4.0 μm (FSSS) and an oxygen content of 4800 ppm. Next, this fine powder was subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 ton.
Press molding in a magnetic field under the condition of n / cm ² , 20 × 20
A molded body of × 15 was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum conditions, and the resulting sintered body was subjected to a first heat treatment at 900 ° C. × 2 hr, and then to 530 ° C.
A second heat treatment was performed at 2 ° C. × 2 hours. The density of the obtained sintered body is 7.55 to 7.58 g / cc, and the oxygen content is 1
000-3600 ppm. For these samples, the relationship between the volume% of the B-rich phase, the residual magnetic flux density Br, and the maximum energy-product (BH) max was investigated. Table 3 shows the results
, The residual magnetic flux density B increases as the B-rich phase increases.
r, the maximum energy product (BH) max is reduced to 2.4
When the volume% is reached, the maximum energy product (BH) max is 42
It is less than MGOe.

[0025]

[Table 3]

[0026]

As described in the foregoing, especially according to the present invention
It has a chromatic microstructure, rare earth having a maximum energy product 42MGOe higher than at normal temperature (BH) ma x, coercive force iHc practicable above 12 kOe, and excellent heat treatability <br/> -Fe- Co- Al-V-Ga- B based firing
A magnet can be provided .

[Brief description of the drawings]

[1] Nd content of the sintered magnet of the present invention and the maximum energy - which is a view to graph an example of correlation between product (BH) max, the residual magnetic flux density Br and coercive force iHc.

Ga content of the sintered magnet of the present invention; FIG and maximum energy - which is a view to graph an example of correlation between product (BH) max, the residual magnetic flux density Br and coercive force iHc.

[Figure 3] Dy content of the sintered magnet of the present invention and the maximum energy - which is a view to graph an example of correlation between product (BH) max, the residual magnetic flux density Br and coercive force iHc.

[4] the oxygen content of the sintered magnet of the present invention and the maximum energy - which is a view to graph an example of correlation between product (BH) max, the residual magnetic flux density Br and coercive force iHc.

FIG. 5 shows that the oxygen content is 5600 ppm and 2000 pp.
EPMA of Nd and oxygen of two sintered bodies different from m
It is a graph which shows the result of the line analysis of (electron beam microanalyzer).

6 is a view to graph an example of correlation between the V content and sintered average grain size of the sintered magnet of the present invention.

FIG. 7 shows the coercive force iHc of the sintered magnet of the present invention and
An example of a composite added <br/> effect of addition of Co and Al on the correlation between the second heat treatment temperature is shown to graph.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-7503 (JP, A) JP-A-5-47529 (JP, A) JP-A-63-18603 (JP, A) JP-A-1- 304713 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 1/032-1/08 C22C 33 / 02,38 / 00

Claims (3)

(57) [Claims] 1. The method according to claim 1 , wherein said Nd and Dy are substantially Nd and Dy.
And Pr rare earth elements of 28 to 32 wt% (Dy is 0.4 to 3 wt%), Co 6 wt% or less (0
Not including) , Al 0.5 wt % or less (not including 0) , B0.
9 to 1.3 wt%, V 0.05 to 2.0 wt%, Ga 0.0
2 to 0.5 wt%, oxygen 500 ppm to 5000 pp
m, the balance being Fe and unavoidable impurities .
There coercive force iHc is more than 12kOe, the maximum energy product (BH) max Ri der least 42MGOe, the heat treatability
An excellent rare earth- Fe- Co-Al-V- Ga - B based sintered magnet , wherein the average Ga content in the rare earth rich phase
Rare earth -Fe- Co-Al-V-Ga- B based sintered magnetic <br/> stone, characterized in that at least twice the total Ga content of sintered magnets. 2. The rare earth- Fe- Co-Al- VG according to claim 1, wherein the B-rich phase is 2 vol.% Or less.
a- B-based sintered magnet. 3. A process according to claim 1 also coated with Ni plating on the surface
Is a rare earth- Fe- Co-Al- VG according to claim 2.
a- B-based sintered magnet.