JPS62270746A - Manufacture of rare earth-type permanent magnet - Google Patents

Abstract

PURPOSE:To manufacture a permanent magnet improved in temperature characteristics, by mixing specific amounts of powders of nonmagnetic elements with a powder of rare earth-Fe-B-Co alloy having a specific composition and by subjecting the resulting powder mixture to compacting and then to hot compaction. CONSTITUTION:The powders of nonmagnetic elements such as Zn, Al, S, In, Ga, etc., are mixed by <=10%, by volume ratio, with the powder of a magnetic alloy consisting of, by atom, 10-20% R (rare earth elements including Y), 5-15% B, <=50% Co, and the balance Fe. The resulting powder mixture is compacted in a magnetic field, etc., and the green compact is then subjected to hot compaction at about 300-1,100 deg.C in vacuum or in an inert atmosphere, etc. In this way, rare earth-type permanent magnets excellent in temperature characteristics and having high magnetic properties can be obtained and, moreover, the green compact can be made dense by means of low-temp. sintering and improvement in the accuracy of product dimension can be attained.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a rare earth element containing Y (hereinafter abbreviated as R), an intermetallic compound consisting of Fe and B, and a non-magnetic Using R2Fe, 4B-M magnet material consisting of element M.

The present invention relates to an R2T14B-M magnet with improved temperature characteristics and a method for manufacturing the same.

[Conventional technology]

JP-A-59-46 as a document on R-Fe-B permanent magnets
Publication No. 008 and materials from the 35th research meeting of the Japanese Society of Applied Magnetics (
May 1980). In addition, Japanese Patent Application Laid-Open No. 1987-64733 can be mentioned as a document regarding the temperature characteristic improving material.

What is disclosed in these documents are all R2T
This is a method of obtaining R-T-B alloy powder with 4B phase as the main phase by a normal pressureless sintering method. After being molded inside, it is sintered at a temperature of 900 to 1200°C. To explain in more detail, when all RTB permanent magnets are manufactured by pressureless sintering, densification is achieved by liquid phase sintering accompanied by the appearance of a high Nd phase (liquid phase). That is, in the sintered body, R2, which is a magnetic phase and a main phase, is present.
T14B phase, B-rich phase which is a non-magnetic phase,
Besides the oxide phase.

There is a Nd-rich phase which is a liquid phase component phase. In general, in this magnetic alloy, depending on the abundance ratio of each of these phases,
Magnetic properties (particularly Br, (BH)max) vary greatly in sintered bodies obtained by current processes.

The volume composition ratio of these non-magnetic phases is about 10% or more.

Other manufacturing methods include annealing of super-quenched materials by melt spinning (Japanese Patent Application Laid-Open No. 60-100402), injection molding and Punt magnet method (Japanese Patent Application Laid-Open No. 59-21990).
No. 4).

[Problem that the invention seeks to solve]

In the case of the pressureless sintering method, in order to obtain sufficient densification of the product, a liquid phase component of 5% or more by volume is required, so the magnetic properties obtained by pressureless sintering are ,There is a limit.

Furthermore, pressureless sintering of RTB magnets is 900 to 1200
Since the process is carried out at a high temperature of ℃, there is no possibility of deformation due to the high temperature.

There is also a limit to the yield in terms of efficiency.

In addition, R
-Fe-B ribbon has magnetic isotropy.

The magnetic properties are much lower than that of sintered magnets, and even if this ribbon is used to make it anisotropic through plastic deformation.

Since the crystal structure in the ribbon is essentially isotropic, properties equivalent to those of sintered magnets cannot be expected.

Furthermore, in the case of the injection molding method and the Punt magnet method, the amount of non-magnetic binder filling the gaps between the magnetic powders needs to be at least 20% by volume, so the properties are extremely poor compared to other methods.

The purpose of the present invention is to solve these problems and further improve temperature characteristics.

(1) Improved properties by reducing the amount of non-magnetic metal binding phase (2)
Yield improvement by improving product dimensional accuracy (3) R2Fe, 4
The object of the present invention is to provide a manufacturing method for achieving improvement in temperature characteristics by replacing a portion of Fe in phase B with "f!:co."

[Means for solving problems]

In order to achieve the above object, 1 the present invention hot-presses a mixed powder of an R-T-B based magnetic powder and a non-magnetic metal with a volume composition ratio of 0 to 10% (0 is included), and a compact. It is characterized by Here, non-magnetic metals.

It is a low melting point metal containing an R-T-B type non-magnetic compound, and may be a powder or a physical or chemical surface coating layer on a magnetic powder. Further, the hot press forming can be performed by any of the so-called real press, hot isostatic press, and extrusion, but real press and hot extrusion are suitable from the viewpoint of product dimensional accuracy.

In other words, in the present invention.

(1) Using non-magnetic metal to promote densification by pressure forming (2) Increasing the coercive force of the magnet by wrapping magnetic particles in a smooth interface (3) Using hot pressure forming In other words, the reduction of Br due to both the reduction of the non-magnetic phase using the flow of the non-magnetic phase and the plastic deformation of the magnetic phase, and the suppression of the reaction between the non-magnetic metal and the magnetic phase due to short-term densification. Improvement (4) Temperature characteristics can be improved by substituting a part of Fe in the R2F014B phase with Co.

The permanent magnet material applied to the present invention is represented by the general formula %, where R in the formula is Yf: one or more rare earth elements are used. Also, M in the formula
is Zn, At*S, In, FetGa, Sn, Te, G
One or more of e, Cu, and PJ, or an alloy of these elements with a rare earth element or B is used. Also (1
) formula, 0.65≦x+y≦0.85 0<y≦0.5 0.0
5≦2≦0.15. If the amount of FexCoy is too large, Br will improve but He will be extremely reduced, and if it is too small, (BH)m will decrease due to the decrease in Br, so 0
．． 65≦x+y≦0.85. Also, a part of Fe is C
By replacing with o, one Curie point (Tc
) increases, but Hc tends to decrease with the amount of Co substitution. In addition, if the substitution is 0 or 5 or more, the deterioration of the He will be significant, which is not desirable due to the characteristics of the permanent magnet material, so O
It is necessary to satisfy <y≦0.5.

B has a remarkable effect on improving magnetic properties, but 0.15
Exceeding this will result in deterioration of characteristics.

It was set as 0.05≦2≦0.15.

Further, the non-magnetic metal M is set to 0 (t≦10) because if the amount is too large, the Br decreases significantly and is not suitable for the purpose of the present invention.

The magnet material represented by formula (1) is R4-8-y-zFeX
A mixed powder of a powder having a composition of coyBz, a non-magnetic metal element and alloy M, or a mixed powder compact is
It is produced by hot pressing in a vacuum or inert atmosphere at a temperature range of 1100°C.

Here, the temperature during hot pressing is 300 to 11001:
The reason for this is that at temperatures below 300°C, sufficient densification of the compact cannot be obtained, and at temperatures above 1100°C, grain growth of R-Fe-Co-B magnetic fine particles and reaction between the magnetic phase and the non-magnetic element or alloy are significant. This is because good magnetic properties cannot be obtained.

<Example 1> By high-frequency heating in an argon atmosphere using Nd, Fe, Co, B'' with a purity of 95 or higher
1sFe bsCO, Nd with a composition of b B 6
Nine gots having the main phase of 2(FeCo)14B were obtained.

Next, this ingot was subjected to phase pulverization, and then wet pulverized using a goal mill to an average particle size of about 4 μm. Next, the obtained fine powder f is 95 vol 1%, and the remaining 5 vol 1% has a purity of 99
．． 9% or more of non-magnetic elements Zn, AltS + In,
One type of powder among Ga, Ge, Te, Cu, and Pb powder.

The mixed powders were mixed at a volume ratio of 95:5 and uniformly dispersed in a ball mill to produce 10 types of Nd13Fe65Co, 6B as shown in Table 1 as samples 1 to 10.
A mixed powder of No. 6 and non-magnetic powder was obtained. these.

The powder was heated in a 20K11e magnetic field for 1. Molding was carried out at a pressure of Ot/m2. Finally, these molded bodies were heated to 600°C in a vacuum.
At a temperature of 1. A pressure of Ot/6n2 was applied and hot pressing was carried out for 15 minutes. Table 1 shows the characteristics of the magnet thus obtained and the results of measuring V, S, M and Te. Sample A11 is listed in Table 1 as Comparative Example 1, and does not contain any non-magnetic elements, and its magnetic properties are so small that they can hardly be used practically. On the other hand, samples &1 to 10 contain non-magnetic elements, and due to hot pressing, Nd2
(FeCO), sintering is promoted while suppressing grain growth of the 4B phase as much as possible. This makes iHc thicker L, Br
We are also improving (BH) max.
40 (MGMe) or more, and the non-magnetic element is At, it is even better than 48 (MGMe), which can be said to be the highest quality of permanent magnets to date.

Also, as a reference example, Nd 1sF e 62CO16B
The magnetic properties and Tc of the sintered body having the composition of
2 is listed in Table 1.

In the following, the non-magnetic element M is magnetic phase Nd2 (FeCo), 4
Because it has a lower melting point than phase B, it becomes a liquid phase at low temperatures,
Because the surface of the magnetic phase is thinly coated, and the pressure and high temperature are applied, the reaction with the non-magnetic M element mixed with the magnetic phase is suppressed as much as possible, and the magnetic phase produced by the normal sintering method and R- r
This is considered to be because reactions in the ich phase, B-rich phase, or oxide phase do not exist or are suppressed as much as possible.

As a reference example, the composition and data for the normal sintering method are shown for sample &12, but as mentioned above, the composition and data for the normal sintering method are set taking into account the presence of the Nd-Jich phase and the B-rich phase. Therefore, samples 1 to 10 were pruned and rare earth R
It is necessary to increase the number of samples 1 to 1 according to the present invention.
0, it can be said that the magnetic phase should have a composition close to the stoichiometric composition.

<Example 2> Nd 1□, 6Fe 63. obtained in Example 1. o”
, s, 6Bs, a I n 3 (Penni 3) at a temperature of 200 to 1200°C in whole Ar.
．． A pressure of Ot/crn was applied and hot-breathed for 155 minutes. The magnetic characteristics at this time are shown in FIG. 1, and show higher magnetic characteristics than conventional sintered magnets.

As shown in Figure 1, the temperature of the hot press is 400℃.
Until now, as the sintering density d increased, the residual magnetic flux density Br also increased, and at temperatures above 400°C, d was approximately 7.6 (gr/c
c), p is constant, and Br takes a nearly constant value up to 900°C.

On the other hand, iHc becomes magnetic Nd-Fe-
Because the reaction between the Co-B phase and the non-magnetic Co-n phase is insufficient, the size is small, and at temperatures above 900°C, the reaction occurs too much, causing the magnetic phase to be swallowed by the non-magnetic phase, resulting in grain growth. Therefore, as the temperature increases, Br deteriorates,
iHc has also become smaller.

Because of this, (BH)max is also 400℃~9
At a hot press temperature of 00°C, it is large, preferably 50°C.
Temperatures between 0 and 700°C are maximum.

〔effect〕

As explained above, according to the present invention, there is provided a magnetic powder having an R2Fe14B phase as a main phase, and a magnetic powder having an R2 (Fe Co ) 14B phase as a main phase in which a portion of Fe is replaced with CO.

A permanent magnet that has excellent temperature characteristics by hot pressing after mixing non-magnetic metal powder, and has higher magnetic properties than R-T-B magnets manufactured by conventional sintering methods. can be obtained.

Furthermore, according to the present invention, the compact can be densified at a lower temperature than conventional sintering methods, and the dimensional accuracy of the product can be improved.

[Brief explanation of drawings]

Figure 1 shows Nd12.6”e63.0 made by hot pressing.
FIG. 2 is a diagram showing the relationship between hot press temperature and magnetic properties of co15.4B5.8Ins.

Claims (2)

[Claims] (1) An alloy consisting of 10 to 20% R (where R is a rare earth element including Y) in atomic percentage, 5 to 15% B (boron), 50% or less Co (cobalt), and the balance Fe (iron). A method for producing a rare earth permanent magnet, which comprises mixing powder with a powder of a non-magnetic element at a volume ratio of 10% or less (not including zero), forming the mixed powder, and then hot-pressing the mixed powder. (2) The manufacturing method according to claim (1), wherein the hot pressing is performed at a temperature range of 300 to 1100°C in a vacuum or an inert gas atmosphere.