JPS62128504A - R-b-fe group sintered magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain and R-B-Fe group sintered magnet having larger coercive force (iHc) and excellent magnetic characteristics by compounding a specific quantity of at least one kind of the borides of Al and C to R-B-Fe group alloy powder and mixing, molding, sintering and thermally treating the whole. CONSTITUTION:R-B-Fe group alloy powder or mixed powder capable of being brought to the same composition as said powder is prepared. 0.05-3.5wt% boride powder of Al and C is compounded to the powder, and molded and consolidated by a compression press, etc. Molding pressure of 0.5-10t/cm<2> is preferable for molding and consolidation. A non-oxidizing atmosphere is desirable as an atmosphere, and said process may also be executed in the atmosphere, such as a vacuum, an inert gas or a reducing gas. A molded shape acquired is sintered at a temperature of 900-1,200 deg.C. It is desirable that sintering is conduct in the non-oxidizing atmosphere for preventing the oxidation of an R element. That is, the atmosphere of the vacuum, the inert gas or the reducing gas is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is an R-B-Fe sintered magnet whose coercive force (iHc) is improved by adding boride.

[Conventional technology]

In recent years, Nd-B-Fe permanent magnets have been invented that have higher magnetic properties than conventional Sm-Co magnets and do not necessarily contain Sm or Co, which are expensive resources. It was done.

(Sayo et al., J. Appl. Phys., 55(6), 1
5 March 1984, p2083-2087. and Japanese Unexamined Patent Publication No. 59-46008, No. 59-20420
(Refer to Publication No. 9) They disclose that as a manufacturing method, an alloy ingot obtained by melting and casting is crushed, press-formed while applying a magnetic field as necessary, and further sintered.

[Problem that the invention seeks to solve]

However, with these conventional manufacturing methods, it has not been possible to obtain a sufficiently satisfactory coercive force (iHc) in terms of magnetic properties.

The present invention solves the above-mentioned problems of the prior art and has a coercive force (
It is an object of the present invention to provide a manufacturing method capable of obtaining an R-B-Fe-based sintered magnet with a large iHc) and excellent magnetic properties.

[Means for solving problems]

That is, the present invention provides an R-
Further, borides of AA and C, that is, A i B2. B
It is characterized by blending 0.05 to 3.5% by weight of at least one type of C, followed by mixing, molding, sintering, and heat treatment.

To explain the present invention in detail, first, an R-B-Fe alloy powder having a predetermined component or a mixed powder that can have the same composition is prepared by known means. For example, lysis.

The alloy powder is produced by a method of casting an ingot into powder, a method of melting and atomizing, or a reduction diffusion method using a rare earth oxide as a starting material. A small amount of the above-mentioned alloy powder (transition metal powder representing a portion of Fe).

Even if a mixed powder substituted with one or more of boron powder, rare earth metal powder, B-transition metal alloy powder, R-transition metal alloy powder, etc. is used as a substitute, the effects of the present invention are not lost.

Add Aj2 to the above powder. The boride powder of C is 0.05~
3.5wt% is blended.

If it is less than 0.05% or more than 3.5%, the effect will be small, so it is set at 0.05 to 3.5 wt%.

The mixed powder obtained by the above method is molded and compacted using a compression press or the like.

For the above-mentioned molding-consolidation, a molding pressure of 0.5 to 10 t/cnl is best, and if necessary, a magnetic field (5 t/cnl) is applied during molding.
By applying KOe or more), the magnetic properties are improved. The series of molding and compaction may be performed wet or dry, and may be performed at a high temperature other than room temperature.

The atmosphere is preferably a non-oxidizing atmosphere, and may be carried out, for example, in a vacuum, an inert gas, or a reducing gas. The obtained molded body is sintered at a temperature of 900 to 1200''C. If the temperature is less than 900°C, the density will not increase and Br will not be sufficient, and if it exceeds 1200°C, Br and squareness will decrease.

Sintering is preferably performed in a non-oxidizing atmosphere to prevent oxidation of the R element. That is, a vacuum, an inert gas, or a reducing gas atmosphere is preferable. Note that the rate of temperature increase from room temperature during sintering is not particularly specified, but
By maintaining the temperature in the 800° C. range for at least 0.5 hours, it becomes possible to improve the temperature uniformity of the heated portion and to perform degassing treatment in a vacuum. Or cracking (such as stearate used as a lubricant)
Hydropyrolysis) can also be carried out in a hydrogen gas atmosphere. Therefore, the atmosphere for sintering should be vacuum, inert gas (e.g. Ar), or reducing gas (e.g. H,
) is preferable. The cooling rate after heating and holding is not particularly specified, but it is 0.5 to b. This is because the variation in magnetic properties due to treatment is reduced. Further, cooling may be performed once to room temperature, or sintering and heat treatment may be performed continuously, such as cooling to about 500° C. and raising the temperature again for the next heat treatment.

After the above sintering, in order to further improve the magnetic properties,
Aging treatment is performed at 00 to 700°C, but if necessary, an intermediate heat treatment of holding and slow cooling at 800 to 1000°C is performed before aging to further improve the magnetic properties. Heat treatments such as aging treatment and intermediate heat treatment are preferably performed in a non-oxidizing atmosphere, as in the case of sintering.

The aging treatment may be carried out by holding at 500 to 700°C for at least 0.5 hours and then rapidly cooling. This is because if the temperature is less than s o o'c, the effect will be small, and if it exceeds 700''C, the magnetic properties will deteriorate.

Next, to explain the reason for limiting the components of the rare earth/boron/iron based sintered magnet to which the present invention is applied, the magnet of the present invention contains one or more rare earth elements. (However, R is at least one rare earth element including Y.
species), boron and iron are essential elements. To explain in more detail, R is neodymium (Nd), praseodymium (
Pr) or a mixture thereof (didim) is preferred; other examples include lanthanum (La), cerium (Ce), terbium (Tb), dysprosium (031), holmium (Ho), erbium (Er), europium (CEu), samarium ( Sm), gadolinium (Gd)
.

May contain rare earth elements such as promethium (Pm), thulium (Tm), ytterbium (Yb), lutetium (U), and indolium (Y), with a total amount of 8
~30 atomic%. This is because if it is less than 8 atomic %, sufficient coercive force cannot be obtained, and if it exceeds 30 atomic %, the residual magnetic flux density decreases. Boron B is contained in an amount of 2 to 28 atomic %. This is because if it is less than 2 atomic %, a sufficient coercive force cannot be obtained, and if it exceeds 28 atomic %, the residual magnetic flux density decreases and excellent magnetic properties cannot be obtained. Fe is essential as an element other than R and B, and is contained in an amount of 40 to 90 atom %.

If it is less than 40 at%, the residual magnetic flux density (Br) decreases, and 9
This is because if it exceeds 0 atomic %, a high coercive force (iHc) cannot be obtained.

Rare earth/boron/iron based sintered magnets can be created using the above R-B and Fe as essential elements, but as described below, even if some of the iron is replaced with other elements or even if impurities are included, the present invention will still work. The effect will not be lost.

That is, Go of 50 atomic % or less is used instead of Fe0.

It may be replaced with 8 atomic % or less of Ni. This is because if Co exceeds 50 atomic %, high iHc cannot be obtained, and if Ni exceeds 8 atomic %, high Br cannot be obtained. In addition, as elements other than the above, one or more of the Fe elements other than the specified atomic percent below (however, if two or more types are included, the total amount of Fe elements is less than or equal to the value of the element with the maximum value among the contained elements) is considered to be Fe element. Even if substituted, the effects of the present invention will not be lost. The elements are listed below.

Next, examples of the present invention will be described, but the present invention is not limited to these examples.

〔Example〕

Example 1 An alloy ingot was obtained by melting to obtain 16 Nd-88-remaining Fe (atomic %). The alloy ingot was made into a fine powder with an average particle size of 3.5 μm using a show crusher, a brown mill, and a jet mill, and then AIB was applied to this powder.

(average particle size 2.2 μm) were blended and mixed as shown in Table 1 to obtain raw material powder.

Table 1 The obtained raw material powder was molded under a molding pressure of 3t/co! in a magnetic field (10
KOe), and the obtained molded body was molded in vacuum (10”3T
After sintering at 1100°C for 2 hours, the sample was cooled in a furnace, and then heat treated again at 610°C for 1 hour, then rapidly cooled and evaluated for magnetic properties. The results are shown in Table 1.

As shown in Table 1, compared to Aj282 without additive (1), Ajl! By adding B2 (squares 2 to 7),
It can be seen that the coercive force (iHc) is significantly improved. However, the residual magnetic flux density (Br) significantly decreases when using the H/823.8% additive material (N[L?).

Cooling implementation 2 As shown in Table 2, boride powder (average particle size 1.6-2.
2 μm) were blended and mixed, molded, sintered, and heat treated in the same manner as in Example 1, and the magnetic properties were evaluated. The results are shown in Table 2.

Table 2 As shown in Table 2, BC addition (N [L8, 9.10°1
1) as well, an improvement in coercive force is observed as in the case of 8βB2.

In addition, combined addition of BC and 8JB (Il&l12,13
Similar results were observed for ゜14).

However, when the amount added is excessive (Kan 11.N114), a significant decrease in Br occurs as in Example 7.

〔Effect of the invention〕

As described above, the present invention improves the coercive force by adding at least one of AN and C borides, and its industrial application is extremely large.

Claims (1)

[Claims] 1. R-B-Fe alloy powder containing R (where R is at least one rare earth element including Y), B and Fe, or a mixed powder having the same composition. further A
lB_2, at least one type of BC 0.0% by weight
Manufacturing method 2 of R-B-Fe based sintered magnet characterized by blending 5 to 3.5%, mixing, molding, sintering and heat treatment, at least one of AlB_2 and BC by weight R-B- characterized in that it is blended in an amount of 0.05 to 3.5%.
Fe-based sintered magnet.