JPS61157659A - Rare earth magnet - Google Patents

Abstract

PURPOSE:To improve temp. characteristic of magnet without deteriorating magnetic characteristic, by displacing a part of Nd and a part of Fe by Dy and Co respectively in Nd-Fe-B permanent magnet. CONSTITUTION:Conventional Nd-Fe-B permanent magnet is superior in magnetic characteristic such as saturation flux density, coercive force, max. energy product, but has low Curier point and extremely large irrevercible variation ratio, thus is inferior than the other permanent magnet in relation to temp. characteristic. A part of Nd is displaced by Dy of the same rare earth having large anisotropic magnetic field, for improving coercive force dominating irreversible variation ratio for covering the fault. Further a part of Fe is displaced by Co, for preventing deterioration of sintering property and decrease of density due to the displacement of Dy, and improving Curie point and irreversible temp. variation rate, to develop rare earth permanent magnet having compsn. exhibited by a formula (1), superior in both of magnetic and temp. characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnet made of a rare earth metal (R) and a transition metal (T), typified by a Nd-Fe-B permanent magnet.

[Prior art and its problems]

In recent years, reports have been made regarding Nd-Fe-B magnets, and Nd-Fe-B 5-element alloys have a saturation magnetic flux density βr.
is 12.5 to 12.8 (kG), holding force r) (c is 9.0 to 10.0 (koe), maximum energy product (B
-H) m is 35.0 to 38.0 (MGOe), which is far superior to other magnets, but on the other hand, the Curie point Tc is 310°C, which is lower than other permanent magnets.
Also, the reversible temperature change rate (temperature coefficient of βr) is -0,126%
/°C, which is intermediate between Sm-Co magnets and ferrite magnets, and the rate of irreversible change β1 is also extremely large, making it inferior to other magnets in terms of temperature characteristics.

[Purpose of the invention]

In view of the above points, an object of the present invention is to obtain a rare earth magnet whose temperature characteristics are improved without deteriorating the magnetic characteristics.

[Structure of the invention]

In order to achieve the above object, the present invention has an irreversible change rate β
In order to improve Ha, which affects i, the negative part of Nd is replaced with Dy, which has a large anisotropic magnetic field HA, and one key point is to prevent deterioration of sinterability and decrease in density caused by this Dy substitution. In order to improve the reversible temperature change rate β, a part of Fe is replaced with Co.

That is, according to the present invention, the compositional formula of the material is (Nd1-X
DyX)z(Fe1-YcoY)wBl-2-w where X is O~0.5°Y is O~0.512 is 0.1~O3
2 and W are o, 75 to 085, and a rare earth magnet produced by powder metallurgy is obtained.

In the present invention, each subscript XI Yl zIW in the alloy having the above composition
Optimal conditions are defined in the range for the following reasons.

Rare earth component (Nd1-xDyx), o≦X≦0.5
This is because if Dy is replaced by 0.5 or more, HC increases but βr decreases extremely, making it impossible to obtain optimal magnetic properties and resulting in poor sinterability.

Next, the Fe-based component is (Fe 1yCoy), o
The reason for setting ≦Y≦0.5 is that when Y becomes 05 or more, β1 and HC decrease extremely. Regarding the z and w values, when W is within the range of 075 to 085 and Z becomes 0.2 or more, HC increases, but conversely βr decreases;
When it becomes less than 1, βr increases, but conversely Hc decreases.

In other cases, even if 2 is changed, appropriate magnetic characteristics cannot be obtained. Also, in the phase diagram, precipitation of phases other than those involved in magnetic properties can be seen in ranges other than those mentioned above.

Rare earth magnets are made from the above composition using the general powder metallurgy method, which involves melting and pulverizing.

Orientation in a magnetic field, compression molding, sintering and aging are performed in this order.

Melting is performed in a vacuum or inert atmosphere using arc high frequency, etc., and pulverization is divided into coarse pulverization and fine pulverization. This is done using a goal mill, vibration mill, jet mill, etc.

Orientation in a magnetic field and compression molding are usually performed simultaneously in a magnetic field using a mold. Sintering is 1000-1150℃
in vacuum and inert atmosphere in the range of 6.
It is carried out at temperatures ranging from 00 to 900°C.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail.

Example-1 Na with a purity of 98 wt% (the remainder being Ce, Pr, etc.) was 33%. .

Ternary alloy (A) NdO, 45Fe0.79BO, Q6 such that B is 1.0 wt% and the balance is Fe,
Ternary alloy with the remainder being Co (B) NdO, 15
0.79B0.06 was melted by high frequency heating in an argon atmosphere to obtain an ingot.

Next, after coarsely pulverizing this alloy, the mother alloy of (A), 03) was obtained (Fe1-YCoY). ,7. TeY is 0,0.
They were weighed and blended to give a ratio of 2, 0.4, 0.6° and 0.8, 1.0°, and were pulverized to an average particle size of about 3.0 μm using a Golle mill. This fine powder was heated under a magnetic field of 10 koe for 1. It was molded at a pressure of Oton/2m2. This green compact was sintered in a vacuum and argon atmosphere between 1040°C and 1100°C, rapidly cooled, and then aged in a temperature range of 600°C to 900°C.

FIG. 1 is a diagram showing the magnetic characteristics at that time. As shown in Figure 1, when increasing the amount of +Co substitution, β7-Y reaches its maximum around 09-03, but rHc and (B-H)m decrease.

If it becomes 05 or more, it will be extremely degraded. As mentioned above (Fe
1-yCOy), it is found that the optimum range for Y is O to 0.5.

Example-2 Ternary alloy (C) using Dy in place of Nd in the master alloy (A) used in Example-1 DyO, 15FeO, 79B
0.06 was melted by high frequency heating in an argon atmosphere to obtain an ingot. Then, after crushing this alloy, (
A), (c) mother alloy (Nd1-xDyX)O,
+5 and X is 0.0.2, 0.4゜06.
1060°C) 1 aging treatment was performed.

FIG. 2 is a diagram showing the magnetic characteristics at this time. As shown in FIG. 2, when the amount of Dy substitution was increased, βT decreased but rHc increased, and 20 (koe) was obtained when X was 0.2. However, when X becomes 0.5 or more, β, , (B-H)m deteriorates extremely, and the characteristics as a magnet are insufficient to perform one function, and there is also the problem that it is difficult to magnetize. Become.

Note that the density ρ(&/cn1') is almost horizontal, clearly indicating that the sinterability is improved.

As mentioned above, in (Nd1-XDyx), X is O~0
It can be seen that the range of 5 is optimal.

Example-3 The master alloys (A) and (B) used in Example-1 were (F e
1yCOy) and Y is 0, 0.1, 0.2, 0.3
They were weighed and blended so that the following results were obtained, and they were subjected to fine pulverization, molding in a magnetic field, sintering, and aging treatment in the same manner as in Example-1.

Table 1 shows the magnetic properties at that time, y=Q, and the linearity when 0.3.

Table 1 FIG. 3 is a diagram showing the Curie point Tc and the reversible temperature change rate βゎ at that time. From the graph of one point of cucumber in Figure 2, the addition of Co shows a significant improvement.

When Y=03, the temperature was 530°C, which exceeded that of a ferrite magnet. In addition, the reversible temperature change rate βr changes from -0,126%/°C in the case of a ternary system to -o, o due to CO substitution.
Although this value is less than about half of os%/°C, and is somewhat inferior to that of Sm--Co magnets, it has sufficient temperature characteristics to function as a magnet. As described above, CO substitution can significantly improve the Curie point and reversible temperature change rate compared to the 93-element system. However, since the IC was low, the cine reversible temperature change β1 was poor, and this was improved by Dy substitution in the next example, which will be explained later.

Example-4 Ndo, 5(Feo, 7COo,
3) 0.79Bo, part of Nd in 06 wt% ratio is 1
When replaced with 0% Dy, a 5-element alloy υ) (NdO, 9D
y0.1) 0.15 (FeO, 7”0.3) 0.79B
0.06 was melted by high frequency heating in an argon atmosphere to obtain an ingot. After coarsely pulverizing the alloy, it was subjected to fine pulverization, compaction in a magnetic field, sintering, and aging treatment in the same manner as in Example-1.

Table 2 shows the magnetic properties and temperature characteristics at that time together with all the data of Example 3 (right side of Table 1). As shown in Table 2, compared to the four-element system of Example 3, the Dy-substituted product decreases βT but improves tHc, and can obtain 12 (koe). There is almost no difference in the rate of irreversible change βi, but the rate of irreversible change βi has been significantly improved due to the increase in c.In this case, the rate of irreversible change β1
is up to 80° when the permeance coefficient P is 1 and 1
It shows the rate of change in magnetic flux density when heated to 00°C and lowered to room temperature.

Example 5 for the rest of the day The composition is (Ndi-XDyX)0.15(Fe0.7co
0.3) 0.79B0.06 'However, x = Q~0
A sintered magnet was obtained in the same manner as in the example described above so that the magnetic flux was within the range of 6.

Figures 4 and 5 show β1 of the magnet obtained as described above.
+ Note that β1 is P
This is the value obtained when heating to 80° and lowering to room temperature when =1.

What can be said from Figures 4 and 5 is that X, that is, Dy
As the amount of substitution increases, β decreases and rHc increases, showing the same tendency as shown in FIG. 2, but it can be seen that the rate of irreversible temperature change is significantly improved.

〔Effect of the invention〕

As is clear from the above examples, according to the method of the present invention, by replacing a portion of Nd with Dy and a portion of Fe with Co, a reversible temperature change can be achieved at a single Curie point.

We were able to obtain a rare earth magnet with improved temperature characteristics of irreversible temperature change.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the magnetic properties of the rare earth magnet obtained in Example-1, Fig. 2 is a diagram showing the magnetic properties in Example-2,
FIG. 3 is a diagram showing the magnetic characteristics of Example-3, and FIGS. 4 and 5 are diagrams showing the magnetic characteristics of Example-5. Fig. 1 Ndα15 (Hi C1 I・0Y) 079″30 concave Fig. 2 06
Fig. 4 (Nd1-x DVX)O, +5 (Fco7Cca
3) o7q Bo, 06--chiX (Nd 1-7"jX) 0.+5"eo, '7COO3
) 0.7 (l Bo, 06 procedural amendment (voluntary) Showa 17/2θ

Claims (1)

[Claims] The composition of the material is the following compositional formula (Nd_1_-_XDy_X)_Z(Fe_1_-_Y
Co_Y)_wB_1_-_Z_-_W However, 0≦X≦
0.5, 0≦Y≦0.5, 0.1≦Z≦0.2, 0.75≦W≦0.85, and is a permanent magnet manufactured by a powder metallurgy method, and the magnetic properties change with temperature. 1. A rare earth magnet characterized by improved properties such as Curie point, reversible temperature change rate, and irreversible temperature change rate, and improved sinterability during sintering.