JPH06275414A - Nd-fe-b based permanent magnet - Google Patents

Abstract

PURPOSE:To provide a title magnet having a maximum energy product (BH)max of 42MGOe or more and a coercive force iHc of l2KOe or more. CONSTITUTION:An in-field press-molded compact of a powder obtained from an ingot of the composition of Nda-Dyb-B1.04-V0.59-Gac-Co0.20-Al0.35-Feba1(wt%) is sintered at 1080 deg.C X 3hr sintering under vacuum and heat-treated at 900 deg.C X2hr, 530 deg.C X 2hr, so that a sinter of 7.55-7.58g/cc density, 1100-4000ppm oxygen content is obtained. An examination result of the relation Nd content between magnetic characteristics with Dy=1.0wt.%, Ga=0.06wt.% with regard to that sinter shows that coercive force iHc increases with an increase in Nd content, but residual flux density Br decreases, and that lowering Dy+Nd content down to 32wt.% or less by complex addition of Nd, Dy, Ga can provide an excellent maximum energy product (BH)max and coercive force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet containing neodymium (Nd), iron (Fe), cobalt (Co) and boron (B) as main components, and particularly Nd- which has excellent energy product and heat resistance. The present invention relates to a Fe-B system sintered permanent magnet.

[0002]

2. Description of the Related Art Sintered Nd-Fe-B magnets are SmCo
_Since it has a high energy product (BH) max as compared with a ₅ series sintered magnet or a Sm ₂ Co ₁₇ series sintered magnet, it has come to be used in various applications. However,
Since Nd-Fe-B system sintered magnets are inferior in thermal stability to these Sm-Co system sintered magnets, various attempts have been proposed 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 And at least one, 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 1 type, M is selected from Nb, W, V, Ta and Mo 1
Element or two or more elements, 0 ≦ x ≦ 0.7, 0.0
2 ≦ y ≦ 0.3, 0.001 ≦ z ≦ 0.15, u ≦ 0.1,
4.0 ≦ A ≦ 7.5. ) Is disclosed.

[0003]

Recently, there has been a demand for further miniaturization of a device using a permanent magnet. Along with this, a permanent magnet having excellent thermal stability and a high energy product is required. Appearance is desired. JP-A-64-
The permanent magnet described in No. 7503 has improved coercive force iHc and excellent thermal stability by adding Ga, but cannot satisfy the above requirement with respect to 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 a magnet having this level of coercive force is 40M.
It is less than or equal to GOe. Therefore, the present invention has a high maximum energy product (BH) max of 42 MGOe or more, and
Coercive force iH that can be practically used with 2 KOe or more
An object is to provide an Nd-Fe-B system magnet having c.

[0004]

Means for Solving the Problems In order to solve the above problems, the present inventor has studied the composition of the Nd-Fe-B magnet in detail, and has obtained the following findings. (1) Energy product (BH) ma if Nd amount is reduced
Although x increases, its coercive force iHc decreases. (2) Although it is effective to add Ga in order to compensate for the decrease in coercive force iHc caused by decreasing the amount of Nd,
The effect of improving the coercive force iHc of a is saturated by the addition of a fixed amount, and the decrease in the coercive force iHc cannot be sufficiently compensated. (3) To improve the coercive force iHc that cannot be compensated by adding Ga, add D
Nd-Fe-B system having a high energy product (BH) max of 42 MGOe or more and a coercive force iHc of 12 KOe or more by adding y in a range in which y is effective and the residual magnetic flux density Br is not so lowered. A magnet is obtained. The present invention has been made based on the above findings, and Nd
And Dy 28 to 31 wt% (where Dy is 0.4 to 3
wt%), Co6 wt% or less, Al 0.5% or less, B0.
9-1.3 wt%, V0.1-2.0 wt%, Ga0.02
~ 0.5 wt%, oxygen 500 ppm ~ 5000 ppm,
Nd-Fe-B consisting of balance Fe and unavoidable impurities
Nd- which is a system magnet and has a coercive force iHc of 12 kOe or more and a maximum energy product (BH) max of 42 MGOe or more.
Fe-B type magnet.

The reasons for limiting the components of the Nd-Fe-B system permanent magnet of the present invention will be described below. Nd and Dy In the present invention, Nd and Dy are contained in the range of 28 to 32 wt% (however, Dy is 0.4 to 3 wt%). As shown in Examples described later, the smaller the Nd amount, the (BH) ma
x is effective in improving the residual magnetic flux density Br, but the coercive force i
Decrease Hc. In the present invention, Dy is added to improve the coercive force iHc. This Dy raises the Curie point Tc and increases the anisotropic magnetic field (H _A ) to contribute to the improvement of the coercive force iHc. However, as the content increases, the residual magnetic flux density Br decreases and the maximum energy product (B
H) max is also reduced. Therefore, the content of Dy is set in the range of 0.4 to 3.0 wt%. The most desirable amount of Dy is 0.7 to 1.5 wt%. When the Nd content decreases, α-Fe is generated in the ingot and it is difficult to expect an increase in (BH) max. On the other hand, when the Nd content increases, the Nd rich phase increases and (BH) max decreases. From the above, the total amount of Nd and Dy is 28 to 32.
wt%. Note that a part of Nd can be replaced with another rare earth element (excluding Dy) such as Pr.

In the present invention, Co is the residual magnetic flux density Br.
The effect of improving the corrosion resistance of the magnet alloy itself with almost no decrease in the corrosion resistance and improving the corrosion resistance by improving the adhesion of the Ni plating which is the corrosion resistant coating. Further, Fe in the main phase (Nd2Fe14B) is replaced with Co, which also has the effect of raising the Curie point Tc. 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 deteriorated.
Therefore, the Co content is 6.0 wt% or less.

In the present invention, Al has the effect of relaxing the temperature conditions during the heat treatment of the Co-added material. That is, Co
The material containing P has large fluctuations in magnetic properties with respect to fluctuations in heat treatment conditions. If an appropriate amount of Al is added thereto, the magnetic characteristics will not change even if the heat treatment conditions change to some extent. As a result, the production management of the permanent magnets becomes easy, and the permanent magnets with stable quality can be efficiently produced. When the Al content exceeds 0.5 wt%, the residual magnetic flux density Br is significantly reduced. Therefore, the Al content is 0.5 wt%
Below.

B is an essential element in Nd-Fe-B system magnets. When B is less than 0.9 wt%, a high coercive force cannot be obtained, while when it exceeds 1.3 wt%, the B-rich nonmagnetic phase increases and the residual magnetic flux density Br decreases. Therefore, it is set to 0.9 to 1.3 wt%. The preferable content of B is 0.95 to 1.1 wt%.

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. When 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 the desired high energy product cannot be obtained. Therefore, the Ga content is 0.02 to 0.5 wt%. The desirable range of Ga is 0.03 to 0.2 wt%. Ga exerts its effect by being present in the Nd-rich Nd phase in the magnet body, and in particular, the average Ga amount in the Nd phase is the total G
The effect is remarkable when the amount added is twice or more. The Ga content in the Nd phase varies depending on the sintering conditions and heat treatment conditions.

The permanent magnet of the present invention has a composition of 0.1
05-2.0 wt% V is contained. V is the periodic table V
Addition of a metal element belonging to group a has an effect of suppressing coarsening of crystal grains during sintering. This effect improves the coercive force iHc and improves the squareness of the hysteresis curve. In addition, Nd-F with good magnetizability
Although the e-B magnet has excellent heat resistance, the magnetizability is improved by making the crystal grains of the sintered body fine. Therefore, V is an element effective for improving heat resistance. V content is 0.05wt
If it is less than%, the effect of suppressing coarse particles is insufficient.
On the other hand, if the V content exceeds 2.0 wt%, V
Alternatively, a large amount of non-magnetic boride of V-Fe is generated, and the residual magnetic flux density Br and the Curie point Tc are significantly lowered, 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 500 p
pm-5000 ppm. If the oxygen content is less than 500 ppm, the magnet powder and its compacted body are easily ignited, which is dangerous in industrial production. On the other hand, when it is more than 5000 ppm, the amount of Nd and Dy that effectively acts on magnetism is reduced by the formation of oxides with oxygen and Nd and Dy, which makes it difficult to obtain a magnet with high coercive force and high energy product. Become.

The sintered magnet of the present invention can be manufactured as follows. That is, an ingot having a constant composition is manufactured by vacuum melting, and then the ingot is roughly crushed to obtain a coarse powder having a particle size of about 500 μm. This coarse powder is finely pulverized in an inert gas atmosphere using a jet mill to obtain 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 , and then 1
Sinter in the 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.
It has almost no 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 is less than 800 ℃ or 10
If it exceeds 00 ° C, a sufficiently high coercive force cannot be obtained. After the heating and holding, the temperature is cooled from room temperature to 600 ° C. at a cooling rate of 0.3 to 50 ° C./min. If the cooling rate exceeds 50 ° C./minute, the equilibrium phase required for aging cannot be obtained, and a sufficiently high coercive force cannot be obtained. Further, a cooling rate of less than 0.3 ° C./minute requires a long time for heat treatment, which is not economical in industrial production. Preferably, a cooling rate of 0.6 to 2.0 ° C./min is selected. The cooling end temperature is preferably room temperature, but if the coercive force iHc is sacrificed to some extent, the temperature may be up to 600 ° C., and the temperature below that temperature may be rapidly cooled. Preferably, the temperature is cooled to room temperature to 400 ° C.

The heat treatment is further carried out at a temperature of 500 to 650 ° C. for 0.2 to 3 hours. This is the secondary heat treatment. Although it depends on the composition, heat treatment at 540 to 640 ° C. is 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, as in the first heat treatment, cooling is performed at a cooling rate of 0.3 to 400 ° C./min. Cooling can be performed in water, in silicone oil, in an argon stream, or the like. If the cooling rate exceeds 400 ° C./minute, the sample is cracked by the rapid cooling and an industrially valuable permanent magnet material cannot be obtained. If less than 0.3 ° C / min,
An unfavorable phase appears in the coercive force iHc during the cooling process.

[0015]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Example 1) Metal Nd, metal Dy, Fe, Co, fer
A predetermined weight of ro-B, ferro-V, and metallic Ga was weighed and melted in vacuum to produce an ingot having a weight of 10 kg. When the composition of this ingot was analyzed, it had the following composition by weight ratio. _{Nd a -Dy b -B 1.04 -V 0.59} -Ga C -Co 0.20 -A
l _0.35- Fe _bal. (wt%) This ingot was crushed with a hammer and then coarsely crushed in an inert gas atmosphere using a coarse crusher to obtain 500 μm.
A coarse powder having a particle size of m or less was obtained. This coarse powder was finely pulverized in the same inert gas atmosphere using a jet mill to obtain fine powder. This fine powder had an average particle size of 4.0 μm (FSSS) and contained oxygen of 5300 ppm. Next, this fine powder is subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 to.
Press-molded in a magnetic field under the condition of n / cm ² , 20 × 20
A × 15 molded body was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum condition, and the obtained sintered compact was subjected to a first heat treatment at 900 ° C. × 2 hr, and then 530
A second heat treatment of ° C x 2 hours was performed. The density of the obtained sintered body is 7.55 to 7.58 g / cc, and the oxygen content is 1
It was 100-4000 ppm. The ambient temperature magnetic characteristics of these samples were measured, and the results shown in FIGS. 1, 2 and 3 were obtained. Figure 1 shows Dy = 1.0 wt% and Ga =
6 is a graph showing the relationship between the amount of Nd and the magnetic characteristics as 0.06 wt%. The coercive force iHc increases as the amount of Nd increases.
, But the residual magnetic flux density Br tends to decrease. FIG. 2 is a graph showing the relationship between the Ga amount and the magnetic characteristics when Dy = 1.0 wt% and Nd = 29 wt%. G
The coercive force iHc improves as the amount of a increases, but it is 0.08.
The effect is saturated at about wt%. Further, the decrease of the residual magnetic flux density Br during this period is slight. Figure 3 shows Nd
6 is a graph showing the relationship between the amount of Dy and the magnetic characteristics, where = 29 wt% and Ga = 0.06 wt%. Although the coercive force iHc increases as the amount of Dy increases, the residual magnetic flux density Br decreases remarkably, and the maximum energy product (BH) max also deteriorates. 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 in order to combine excellent maximum energy product (BH) max and coercive force iHc. Recognize.

(Example 2) Metal Nd, metal Dy, Fe,
A predetermined weight of Co, ferro-B, ferro-V, and metallic Ga was weighed and melted under vacuum to produce an ingot having a weight of 10 kg. When the composition of this ingot was analyzed, it had the following composition by weight ratio. 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, coarse crushing was further performed in an inert gas atmosphere using a coarse crusher to obtain 500μ _.
A coarse powder having a particle size of m or less was obtained. This coarse powder was finely pulverized in the same inert gas atmosphere using a jet mill to obtain fine powder. At this time, a minute amount of oxygen was mixed into the inert gas to obtain fine powder with various oxygen contents. The fine powder had an average particle size of 4.0 μm (FSSS). Next, this fine powder is subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 to.
Press-molded in a magnetic field under the condition of n / cm ² , 20 × 20
A × 15 molded body was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum condition, and the obtained sintered compact was subjected to a first heat treatment at 900 ° C. × 2 hr, and then 530
A second heat treatment of ° C x 2 hours was performed. The density of the obtained sintered body is 7.55 to 7.58 g / cc, and the oxygen content is 1
It was 000-5800 ppm. The ambient temperature magnetic properties of these samples were measured. The results are shown in FIG. 4, and when the oxygen content exceeds 5000 ppm, the coercive force iHc decreases remarkably, so the oxygen content is set to 1000 to 5000 ppm. Fig. 5 shows oxygen content of 5400ppm and 2000p
EPMA of Nd and oxygen of two sintered bodies different from pm
The result of the line analysis of (electron beam microanalyzer) is shown.
Most of the Nd peaks and oxygen peaks of the sintered body containing a large amount of oxygen overlap each other, and it is considered that a large amount of Nd oxide is formed. On the other hand, in the sintered body containing a small amount of oxygen, the Nd peak and the oxygen peak overlap with each other, but the Nd peak which exists alone is considerably observed. That is, in the sintered body containing a large amount of oxygen, Nd exists a lot as an oxide that does not contribute to the magnetic properties.
A sintered body containing a small amount of oxygen has a large amount of Nd that effectively contributes to the magnetic properties. In FIG. 5, the circled portion is a peak where Nd exists independently of oxygen.

(Example 3) Didymium metal (Nd 70 wt)
% -Pr30wt%), metal Dy, Fe, Co, fer
A predetermined weight of ro-B, ferro-V, and metallic Ga was weighed and melted in vacuum to produce an ingot having a weight of 10 kg. When the composition of this ingot was analyzed, it had the following composition by weight ratio. _{Composition: (Nd + Pr) 28.5 -Dy} 0.6 -B 1.05 -Vx
-Ga _0.05 -Co _2.25 -Al _0.35- Fe _bal. (Wt%) After crushing this ingot with a hammer, coarse crushing was further performed in an inert gas atmosphere using a coarse crusher to obtain 500μ _.
A coarse powder having a particle size of m or less was obtained. This coarse powder was finely pulverized in the same inert gas atmosphere using a jet mill to obtain fine powder. At this time, a minute amount of oxygen was mixed into the inert gas to obtain fine powder with various oxygen contents. The fine powder had an average particle size of 4.0 μm (FSSS). Next, this fine powder is subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 to.
Press-molded in a magnetic field under the condition of n / cm ² , 20 × 20
A × 15 molded body was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum condition, and the obtained sintered compact was subjected to a first heat treatment at 900 ° C. × 2 hr, and then 530
A second heat treatment of ° C x 2 hours was performed. The density of the obtained sintered body was 7.55 to 7.58 g / cc, and the oxygen content was 2
It was 600-4400 ppm. The magnetic properties at room temperature and the average particle size of these samples were measured, and the results shown in FIG. 6 were obtained. As shown in FIG. 6, by containing V, crystal grain growth during sintering can be suppressed, and as a result, the average grain size of the sintered body can be reduced. Further, this effect can be expected to improve the coercive force iHc. Even if the content is 2.0 wt% or more, the average particle size cannot be expected to be reduced so much.
Further, since the maximum energy product (BH) max also decreases greatly, addition of 0.1 to 2.0 wt% is an appropriate amount.

(Example 4) Metal Nd, metal Dy, Fe,
A predetermined weight of Co, ferro-B, ferro-V, and metallic Ga was weighed and melted under vacuum to produce an ingot having a weight of 10 kg. When the composition of this ingot was analyzed, it had the following composition by weight ratio. 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 each ingot with a hammer, further using a coarse crusher and inert gas atmosphere Coarse crushing in 500
A coarse powder with a particle size of less than μm was obtained. This coarse powder was finely pulverized in the same inert gas atmosphere using a jet mill to obtain 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 molded body was produced. This compact was sintered at 1100 ° C. × 2 hr under a substantially vacuum condition, and the obtained sintered compact was subjected to a first heat treatment at 900 ° C. × 2 hr and then a second heat treatment at 500 to 600 ° C. × 2 hr. Was applied. The density of the obtained sintered body is 7.56 to 7.59 g /
The cc content and oxygen content were 2100 to 3300 ppm. The room temperature magnetic characteristics of these samples were measured, and the results shown in FIG.
The results are shown in. As shown in FIG.
The magnetic properties of the alloys containing Co alone have a greater dependence on the secondary heat treatment temperature than those of the alloys without Co and Al. In this case, it is difficult to produce a product having stable characteristics in industrial production. Therefore, the combined addition of Co and Al can reduce the temperature dependence of the secondary heat treatment as shown in FIG. 7, and this problem can be avoided.

Next, Ni is added to the magnet having the above composition (no addition of Co), (addition of Co) and (addition of Co, Al).
Plating was performed and the adhesion was evaluated. The Ni plating was electrolytically plated with a watt bath to a film thickness of 10 μm.
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 it can be seen that the Co additive has excellent plating adhesion. Material Adhesion strength (Kgf / cm ² ) (No Co added) 150 (Co added) 660 (Co, Al added) 685

(Example 5) Metal Nd, metal Dy, Fe,
A predetermined weight of Co, ferro-B, ferro-V, and metallic Ga was weighed and melted under vacuum to produce an ingot having a weight of 10 kg. When the composition of this ingot was analyzed, it had the following composition by weight ratio. Nd _28.5 -Dy _0.80 -B _1.20 -V _1.05 -Gac-Co
_0.15- Al _0.32- Fe _bal. (Wt%) After crushing this ingot with a hammer, coarse crushing was further performed in an inert gas atmosphere using a coarse crusher to obtain 500 μm.
A coarse powder having a particle size of m or less was obtained. This coarse powder was finely pulverized in the same inert gas atmosphere using a jet mill to obtain fine powder. This fine powder had an average particle size of 4.0 μm (FSSS) and contained oxygen of 4300 ppm. Next, this fine powder is subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 to.
Press-molded in a magnetic field under the condition of n / cm ² , 20 × 20
A × 15 molded body was produced. This compact was sintered at 1070 ° C. × 3 hr under a substantially vacuum condition, and the resulting sintered compact was subjected to a primary heat treatment at 930 ° C. × 2 hr, then 5
A second heat treatment was performed at 20 ° C. for 2 hours. 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 amount of Ga in the Nd phase and the coercive force iHc was investigated. The results are shown in Table 1.

[0021]

[Table 1]

(Example 6) Metal Nd, metal Dy, Fe,
A predetermined weight of Co, ferro-B, ferro-V, and metallic Ga was weighed and melted under vacuum to produce an ingot having a weight of 10 kg. When the composition of this ingot was analyzed, it had the following composition by weight ratio. 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, coarse crushing was further performed in an inert gas atmosphere using a coarse crusher to obtain 500 μm.
A coarse powder having a particle size of m or less was obtained. This coarse powder was finely pulverized in the same inert gas atmosphere using a jet mill to obtain fine powder. This fine powder had an average particle diameter of 4.0 μm (FSSS) and contained oxygen of 4800 ppm. Next, this fine powder is subjected to an orientation magnetic field strength of 15 kOe and a molding pressure of 1.5 to.
Press-molded in a magnetic field under the condition of n / cm ² , 20 × 20
A × 15 molded body was produced. This compact was sintered at 1080 ° C. × 3 hr under substantially vacuum condition, and the obtained sintered compact was subjected to a first heat treatment at 900 ° C. × 2 hr, and then 530
A second heat treatment of ° C x 2 hours was performed. The density of the obtained sintered body is 7.55 to 7.58 g / cc, and the oxygen content is 1
It was 000-3600 ppm. For these samples, the relationship between the average Ga amount in the Nd phase and the coercive forces iHc and Hk was investigated. The results are shown in Table 2, and when the average Ga amount in the Nd phase is 1.7 times the Ga addition amount, the coercive force iHc is 11.
It can be seen that it has not reached 7 KOe and 12 KOe.

[0023]

[Table 2]

(Example 7) Metal Nd, metal Dy, Fe,
A predetermined weight of Co, ferro-B, ferro-V, and metallic Ga was weighed and melted under vacuum to produce an ingot having a weight of 10 kg. When the composition of this ingot was analyzed, it had the following composition by weight ratio. Nd _27.5- D
y _2.0 -B _{1.1 / 1.4} -V _1.6 -Ga _0.08 -Co _0.22- Al
_0.30- Fe _{b al.} This ingot was disintegrated with a hammer and then coarsely pulverized in an inert gas atmosphere using a coarse pulverizer to obtain coarse powder having a particle size of 500 μm or less. This coarse powder was finely pulverized in the same inert gas atmosphere using a jet mill to obtain fine powder. This fine powder has an average particle size of 4.0 μm
(FSSS) and oxygen content is 4800ppm
Met. Next, this fine powder is applied with an orientation magnetic field strength of 15 kOe,
Press molding was performed in a magnetic field under a molding pressure of 1.5 ton / cm ² to prepare a 20 × 20 × 15 compact. This molded body was sintered at 1080 ° C. for 3 hours under substantially vacuum conditions, and the obtained sintered body was subjected to a first heat treatment at 900 ° C. for 2 hours and then a second heat treatment at 530 ° C. for 2 hours. did.
The density of the obtained sintered body was 7.55 to 7.58 g / cc, and the oxygen content was 1000 to 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. The results are shown in Table 3, and the residual magnetic flux density Br and the maximum energy product (BH) max decrease as the B-rich phase increases, and the maximum energy product (B
H) max is less than 42 MGOe.

[0025]

[Table 3]

[0026]

As described above, according to the present invention, 4
N having a high energy product (BH) max of 2 MGOe or more and a coercive force (iHc) of 12 KOe or more
A d-Fe-B system magnet is obtained.

[Brief description of drawings]

FIG. 1 is an Nd content, maximum energy product (BH) max, and residual magnetic flux density B of an Nd-Fe-Co-B system sintered magnet.
A graph showing changes in r, coercive force iHc, and squareness ratio.

FIG. 2 is a Ga content, maximum energy product (BH) max, and residual magnetic flux density B of an Nd-Fe-Co-B system sintered magnet.
The graph which showed the relationship of r, coercive force iHc, and squareness ratio.

FIG. 3 is a graph showing the Dy content, the maximum energy product (BH) max, and the residual magnetic flux density B of the Nd-Fe-Co-B system sintered magnet.
The graph which showed the relationship of r, coercive force iHc, and squareness ratio.

FIG. 4 is a graph showing the relationship between the oxygen content, the maximum energy product (BH) max, and the coercive force iHc of the Nd-Fe-Co-B system sintered magnet.

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

FIG. 6 is an average crystal grain size of the sintered body and a maximum energy product (B) with respect to the V content of the Nd-Fe-Co-B system sintered magnet.
H) A graph showing changes in max.

FIG. 7: Co and A of Nd-Fe-Co-B system sintered magnet
The graph which showed the change of the secondary heat treatment temperature dependence by 1 addition.

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[Procedure amendment]

[Submission date] October 12, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Added

[Correction content]

[Figure 7]

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // H01F 7/02 Z

Claims (6)

[Claims] 1. Nd and Dy 28 to 32 wt% (where Dy is 0.4 to 3 wt%), Co 6 wt% or less, Al
0.5% or less, B 0.9 to 1.3 wt%, V 0.05 to 2.
0 wt%, Ga 0.02-0.5 wt%, oxygen 500 pp
An Nd-Fe-B based permanent magnet, characterized in that it has a coercive force iHc of 12 kOe or more and a maximum energy product (BH) max of 42 MGOe or more and is composed of m to 5000 ppm, the balance Fe and unavoidable impurities. 2. The Nd—Fe—B system permanent magnet according to claim 1, wherein the Ga content is 0.03 to 0.2 wt%. 3. The Nd- according to claim 1, wherein the average Ga amount in the Nd phase is at least twice the total Ga addition amount.
Fe-B system permanent magnet. 4. The Nd—Fe—B system permanent magnet according to claim 1, wherein the B-rich phase is 2 vol.% Or less. 5. The method according to claim 1, wherein a part of Nd is replaced with Pr.
4. The Nd-Fe-B based permanent magnet according to any one of 4 above. 6. The surface of the plate is plated with Ni.
Nd-Fe-B type | system | group sintered magnet in any one of.