JPS63282239A - Permanent magnet alloy - Google Patents

Abstract

PURPOSE:To produce a permanent magnet provided with high coercive force by preparing the permanent magnet having the phase consisting of specific ratios of rare earth elements, Fe, B and Co as the main phase and having specific grain size of said phase. CONSTITUTION:The permanent magnet is prepared by a power metallurgy method from the plural phases in which the phase consisting of R2 (Fe14-xCox)14 B (where R denotes the rare earth elements in the combination of or more kinds thereamong in which Nd and Pr are essentially composed, and 0<=X<=8) is regulated as the main phase. Said permanent magnet is then applied to warm working in which the magnet is pressurized in the temp. range of about 600-1,000 deg.C to provide it a strain, and the grain size of R2 (Fe14-xCox) B phase is regulated to 200-10,000Angstrom . The permanent magnet alloy provided with high coercive force is obtd., by such a simple process.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to an R-Fe-B rare earth R magnet alloy, and in particular, to an R-Fe-B rare earth magnet alloy.
This invention relates to an improved permanent magnet alloy in which the crystal grain size of the zFe+4B phase is within a specific range.

"Prior art" R-Fe-B permanent magnet alloy has a high residual magnetic flux density (Br
) and a high intrinsic coercive force (1Hc), it is attracting attention as a new permanent magnet material to replace conventional alnico, hard ferrite, and 5ll-Go magnets (Japanese Patent Application Laid-Open No.
(See Publication No. 9-46008).

The basic composition of this R-Fe-B field magnet alloy is 8 to 30 at% of one type or mixture of R and 2 to 28 at% of B1 with the balance being Fe. In addition to this basic composition, additives include: Co, A/, Dy, Nb+ Ti, Mo
It is also known that compositions with the addition of
(See Publication No. 453).

Generally, the following manufacturing methods are known as methods for manufacturing Nd-Fe-B permanent magnets. That is, after weighing and blending raw materials to a predetermined composition, they are melted in a high frequency induction furnace or the like to form an ingot, which is then crushed. Powder average particle size 0.
In the range of 3 to 50 μm, the intrinsic coercive force (, Hc) is 3 kO
It becomes more than e. When pulverization is performed wet, alcohol solvents, hexane, trichloroethane, trichloroethylene, xylene, toluene, fluorine solvents, paraffin solvents, and the like can be used. The thus obtained alloy powder having a predetermined particle size is compacted in a magnetic field of 7 to 13 kOe. Molding pressure is 0.5-8 tons/cIlz
It is preferable to carry out the test within the range of .

The obtained molded body is sintered at 1000 to 1180°C. A two-stage type heat treatment is used after sintering. 900'C
After heating for X 2 hrs, heat to room temperature at approximately 1°C/min.
Controlled cooling in the range of 550 to 700℃
Keep heated and quench in oil. The resulting structure is shown in Figure 1.
As shown in R2FezB main phase, RzFetB.

It can be classified into three types: a second phase, Ndrich, and a third phase, and the crystal grain size of the R2Fe+J main phase, which provides magnetism, is 10 μm or more. This is because when the powder alloy method is used as the manufacturing method, a reduction in the pulverized particle size due to excessive pulverization leads to an increase in the amount of oxidation due to an increase in the specific surface area, so the particle size of the pulverized powder is 2.
The limit is 5 to 4.5 II m (F, S, S, S). Therefore, the crystal grain size of the sintered body must be 10 μm or more.

On the other hand, by using ultra-quenching technology and heat treatment,
It is possible to realize microcrystals of 1,000 and obtain high Hc (see Japanese Patent Application Laid-Open No. 59-64739.211549°60-9852). However, these alloys are isotropic, and the obtained (B)I)max is also LOMG
Oe is the limit. Further, in order to impart anisotropy, warm working is required, which limits the number of man-hours and the shape of the product (see Japanese Patent Laid-Open No. 100402/1982).

"Problems to be Solved by the Invention" R constituting the R-Fe-B rare earth magnet is mainly Nd, but the single magnetic domain particle diameter of the NdzFezB intermetallic compound is 0.
It is reported to be 26 μm (M, Sagawa et
alProc, of 8th International
nal Workshop on R,E.

magnets and their applica
tion pp, 587-611). Therefore, the grain size of the sintered type can be obtained to be 10 to 10'' times as large as that desired from single domain grain theory.

It has the disadvantage of small Hc.

On the other hand, R-Fe-B magnets produced using ultra-quenching have crystal grain sizes as small as 200 to 1000
(Although c is high, manufacturing costs are high because processes such as hot pressing and warming swaging are required to impart anisotropy, and there are restrictions on the final product shape (J, Lee)
, Appl, Phys, Lett, vo46. Na
8790 (1985)).

"Means for Solving the Problems" In order to solve the above problems, the present invention provides R2 (Fe14
-xCox)+nB (Here, R is one or a combination of two or more rare earth elements centered around Nd+Pr, 0
≦x≦8) as the main phase, and the particle size of the Rz(Fe+4-xcox)+aB phase is 200
~10,000 people.

In other words, in order to extract the original +I(c) of the R-Fe-B rare earth magnet, the present inventors reduced the crystal grain size to 2.
We thought it was important to have 00 to 10,000 people.

As mentioned above, it is impossible to achieve this crystal grain size using normal powder metallurgy, and although it is possible to achieve this using ultra-quenching technology, it is not economical due to problems in terms of man-hours.

Therefore, in order to economically realize a crystal grain size of 200 to 10,000, the present invention uses a method in which a sample prepared by powder metallurgy is warm-processed, strained, and recrystallized.

[For production]

Warm working is performed at a temperature range of 600 to 1000°C.

For warm processing, die forging, warm extrusion, hydrostatic uniaxial compression, etc. can be used.

Primary recrystallization is used as the recrystallization phenomenon, and the warm working temperature, working degree, and aging temperature that affect the recrystallized grain size vary depending on the composition, but the maximum value for working strain is used within the range that does not cause physical racking. Should.

The reason for the limitation regarding crystal grain size will be explained. Grain size is 200
If it is less than 10,000 Å, there is insufficient dust around the Ndrich phase and sufficient mechanical properties cannot be obtained, and if it is more than 10,000 Å, high 1t (C) cannot be obtained.

(Example) The present invention will be explained in more detail with reference to Examples below.

Example I Na(Fed, llIc0O,0IBO,os)s,
An alloy named o was produced by high frequency melting, and the obtained melted ingot was coarsely ground using a jaw cracker, a 7 shear, and a disc mill. Further, fine pulverization was performed using a jet mill to obtain a powder of 3.7 microns (FSSS). The pressure medium of the jet mill was N2 gas, and the pressure was 7 kg/cm''. The Honhui pulverized powder was molded in a vertical magnetic field. The magnetic field strength applied during molding was 8 KOe.
It is.

The compact formed by vertical magnetic field was sintered in vacuum at 1080°C for 2 hours. The sintered body was processed to obtain a sintered body of 15φ×10t. The magnetic properties obtained after sintering are Br-10400G
, mHc~80000e, +)Ic-82000e
, (Bit)max~25.9MGOe.

This magnet was heated to 1000°C and subjected to warm compression processing. Figure 1 shows the relationship between the load and the amount of deformation during the main warm working. The amount of deformation indicates the change in height in %. After 20% deformation, it was taken out from the warm processing machine.

A sample of approximately 16.8φ×Bt was obtained. This magnet is 7
The mixture was heated at 50°C for 10 minutes and cooled to room temperature at a cooling rate of 2°C/min. Thereafter, it was heated at 620° C. for 10 minutes and then rapidly cooled in water. The obtained magnetic properties are Br-10600G, J
c~100000e, +Hc''178000e.

(BH)max ~27. It was IMGOe. The average crystal grain size of this magnet was 8,200.

Example 2 (Ndo, J)'o, +) (Feo, '11
sBo, otssio, oυ3. . The alloy was melted, crushed, formed in a magnetic field, and sintered in the same manner as in Example 1. The magnetic properties obtained were Br-10200G.

Jc~97000e, +Hc~132000e, (
BH) max~23.9MGOe. This magnet was warm worked in the same manner as in Example 1. The deformation was approximately 25%, and a sample of 1.73φ x 7.5t was obtained. This magnet is 75
The mixture was heated at 0° C. for 15 minutes and cooled to room temperature at a rate of 3° C./win. After further heating at 580° C. for 15 minutes, the mixture was rapidly cooled in water.

The obtained magnetic properties are Br-10500G, Jc~10
0000e.

+Hc~245000e, (BH)max ~26.
It was 7MGOe.

The crystal grain size of this magnet was 7200.

(Example 3) An alloy having the composition shown in Table 1 was melted, crushed, formed in a magnetic field, and sintered in the same manner as in Example 1. The obtained magnetic properties are shown in Table 2. The obtained sintered body was processed at 1000°C for 1 hour. The amount of deformation was kept constant at 20%.

The obtained magnet was heated at 800°C for 1 hr and then rapidly cooled in water.
The mixture was further heated at 600° C. for 10 minutes and quenched in water. The obtained magnetic properties are shown in Table 3.

The following margin is "Effects of the Invention" The present invention is a permanent magnetic alloy that can impart high coercive force through a simple process by adjusting the crystal grain size to 200 to 10,000.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between load and deformation amount during warm working.

Claims (4)

[Claims] (1) R_2(Fe_1_4_-_xCo_x)_1_
4B (here, R is one or a combination of two or more rare earth elements mainly Nd and Pr, 0≦x≦8), and the R_2 (Fe_1
_4_-_xCo_x)_1_4B phase particle size is 200
A permanent magnetic alloy characterized in that it has a diameter of ~10,000 Å. (2) The composition of the permanent magnet alloy is R(Fe_1_-_y
＿−＿zCo_yB_z)_A(Here, R is Nd, Pr
One type or a combination of two or more rare earth elements, mainly 0≦x≦0.57, 0.04≦z≦0.15, 4≦
The permanent magnet alloy according to claim 1, characterized in that A≦7.5). (3) The composition of the permanent magnet alloy is R(Fe_1_-_y_-_z_-_vCo_yB_z
M_v)_A (here, R is one type or a combination of two or more rare earth elements, mainly Nd and Pr, and 0≦x≦0.
57, 0.04≦z≦0.15, 0≦v≦0.05, 4
≦A≦7.5, M is Nb, Ga, Si, Al, W, Mo
2. The permanent magnet alloy according to claim 1, wherein the permanent magnet alloy is one type or a combination of two or more types. (4) A patent claim characterized in that, in the method for manufacturing the permanent magnet alloy, an alloy having the composition according to claim 2 is subjected to pulverization, forming in a magnetic field, sintering, cold working, and heat treatment for recrystallization growth. Permanent magnetic alloy according to item 1.