JPS61288047A - Manufacture of permanent magnet alloy - Google Patents

Abstract

PURPOSE:To manufacture a permanent magnet alloy having extremely high maximum energy product by age-treating under specific conditions a rare earth element-B-Fe alloy having specific average grain size. CONSTITUTION:An alloy powder consisting of, as essential elements, R (where R is one or more kinds among rate earth elements including Y), B, and Fe containing inevitable impurities and having 1-50mu average grain size is compacted. The resulting green compact of the above alloy powder is sintered at 900-1,200 deg.C in vacuum or in a gaseous atmosphere containing one kind selected from Ar, He, N2 and a gaseous mixture of N2 and Ar. The sintered compact is then subjected to heating, holding and cooling treatments two or more times under the same atmosphere with adjusting the holding temp. to 400-850 deg.C, followed by age treatment in which final cooling is carried out down to <=350 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a manufacturing method for improving the magnetic properties (particularly the maximum energy product (BH) MAX) of an R-B-re permanent magnet alloy.

[Conventional technology]

In recent years, Nd-B-Fe-based permanent magnets have been invented that have higher magnetic properties than conventional am-Co-based magnets and do not contain Sm or CO, which are expensive resources. (Sayo et al.;
J, Appl, Pkys, 55(6)
15March 1984. P2O83-2087 and JP-A-59-46008, JP-A No. 59-64733
No. 59-217304, No. 59-222
(Refer to Publication No. 564) Among them, the one that mentions in detail the aging treatment after sintering is JP-A No. 59-217.
304, which stipulates that the cooling rate after sintering should be at least 20°C/min, and that the temperature should be raised from K350°C to below the sintering temperature, maintained, and cooled, and the cooling process should be continuous. It is proposed to cool the material directly or in multiple stages (cooling rate 0.2°C/min to 20°C/sec).

[Problem to be solved by the invention]

However, in the aging treatment by these conventional methods, 4πI-
The squareness in the second quadrant of the H curve is still insufficient, but the magnetic properties are sufficiently satisfactory, especially the maximum energy product ((BH)
MAX) has not yet been achieved. (The highest value in Example 1! is 29.2 MGOe, which is still insufficient compared to the potential of 40 MGOe or more of this alloy system.) The present invention solves the problems of the prior art described above.

R-B-Fe with high maximum energy product and excellent magnetic properties
The object of the present invention is to provide a method for producing a permanent magnet alloy.

[Means for solving problems]

The method for producing a permanent magnet alloy of the present invention includes Ru (where Ru is 1211 or more of the rare earth elements including Y), B
An alloy powder made of Fe containing unavoidable impurities with an average particle size of 1 to 50 μm is molded and heated at 900 to 1200°C.
After sintering at a temperature of 400 to 850°C, heating, holding, and cooling treatments are performed at least twice to maintain a temperature of 400 to 850°C, and the final cooling is performed at a temperature of 350°C.
It is characterized by an aging treatment that is carried out to temperatures below ℃.

Furthermore, the aging treatment is performed in vacuum, using Ar, He,
It is carried out in a N2A-rui (Ar+NZ) gas atmosphere.6Also, after sintering and before aging treatment, it is heated to a temperature of 850℃ to below the sintering temperature, and after being held, it is heated to a temperature of 350℃ or below. By performing the cooling process, the magnetic properties are further improved.

[For production]

The manufacturing method of the present invention will be described in detail below. Prior to aging treatment, a magnetic alloy having predetermined components is prepared by a known method (for example, JP-A-59-46008, JP-A-59-64733, JP-A-59-217304). (see official bulletin). That is, electrolytic iron (purity 99.9 wt% or more), B (purity 99 wt% or more), and Nd (purity 99.7 wt%
Weigh the raw materials (above) etc. so that they have the specified ingredients.

The alloy was subjected to high frequency melting and water-cooled copper WVC casting to obtain an alloy ingot. Stamping and milling alloy ingots.

Grind to an average particle size of 1 to 50 μm using a grinding means such as a di-crusher and a jet mill.

This is because if the thickness is less than 1 μm or more than 50 μm, the magnetic properties, especially the coercive force, will deteriorate. Paraffin/stearic acid, stearic acid metal salts (metals include Ca, Mg, Lull, Zn), etc. are added to the obtained fine powder as necessary to form a molding raw material, and the mixture is subjected to 7JO pressure molding. The molding pressure is preferably 0.5 to 10 t/d. In addition, during molding, if necessary, a magnetic field (for example, 5 KOe or more) is applied to create anisotropy in the direction of application, resulting in high magnetic properties. 6. 900 to 1 in a reactive gas atmosphere or a reducing gas atmosphere such as H2.
Sinter at 200°C. Oxidizing gas atmosphere and 900
This is because if the temperature is lower than 1200°C, the basic components will be oxidized or the desired density will not be obtained, making it impossible to obtain high magnetic properties.

After sintering and prior to aging treatment, it is heated to 850°C in a vacuum or in a non-oxidizing gas atmosphere such as an inert gas or a reducing gas.
℃ to a temperature below the sintering temperature, 0.5 to 10
Hold for a period of time and cool down to 350°C or less at a cooling rate of 20°C/min to 80°C.
By performing the cooling process at 0° C./second, the magnetic properties are dramatically improved. This is because when the sintering temperature exceeds 3 and 10 hours, crystal grains grow and the coercive force decreases, and when the sintering temperature is less than 850° C. and less than 0.5 hours, the effect of this treatment is small.

Also, if the cooling rate is less than 20°C/min or more than 800°C/sec, the coercive force will decrease.
C/min to 800°C/sec, and cooling to 350°C or lower is required.

By subjecting the magnetic alloy produced by the method described above to the specific aging treatment according to the present invention, the magnetic properties, particularly the maximum energy product (BH) MAX, are significantly improved compared to conventional manufacturing methods.

In the aging treatment of this invention, first TI = 400 ~
Heat to 850°C. This is because coercive force decreases at temperatures below 400°C and above 850°C. The retention time is t!
=9.5 to 20 hours is good. This is because if the heating time is less than 0.5 hours, the effect will be insufficient, and if the heating time exceeds 20 hours, the sharpness will decrease.

The cooling rate after holding is V1=gQ, 1°C/min to 20°C/
211 seconds is preferable, but outside the above range the characteristics deteriorate. Note that cooling to 350° C. or lower is effective. By performing the above heat treatment two or more times, (BH)M
Although Ax improves, the first heating holding condition (Tx) < t
t), the second heating and holding condition (TzXH) preferably satisfies the conditions T1≧Tz and H≦t2.

Note that heating and cooling after the first heating and cooling heat treatment may be performed continuously, or may be cooled to room temperature.When the product is cooled to room temperature, machining and magnetization work of the product becomes possible. Through the following heating-cooling treatment, rust prevention treatment can be performed at the same time by reaction with atmospheric gas on the surface, and the magnetized state can also be changed to a demagnetized state.The ability of this magnet to be thermally demagnetized is This is because the Chieri temperature is between 300 and 600°C.

After sintering as described above, heat and hold from 850°C to a temperature below the sintering temperature, cool to 350°C or below, and further maintain the temperature at 450°C.
Magnetic properties are improved by aging treatment, which involves heating, holding, and cooling treatments at 00 to 850°C two or more times.

This aging treatment is carried out in a vacuum using Art He
It is preferable to carry out the process in a gas atmosphere of one gas selected from a mixed gas of r N2 tN2 and Ar. This is because, in an oxidizing gas atmosphere, ru in the alloy components is oxidized and the properties deteriorate.

The above-mentioned aging treatment is effective for permanent magnetic alloys such as those disclosed in Japanese Patent Application Laid-Open No. 59-222564. That is, 40 to 90 yen of Fe in terms of atomic percentage
, 2 to 28% B, and 8 to 30% 1 (rare earth metals including Y) as essential components: and one or more of the A elements below the specified amount below (however, A element when containing two or more types) The content of is the core containing A7 (: below the value of the element with the maximum value)
It is a permanent magnet alloy containing.

TI 4.5% or less Ni 8- or less Co
50% or less Bi 5% or less V9.5% or less
Nb 12.5% or less Ta 10.5% or less Cr 8.5%
Below Mo 95% or below W 9.5% or below fV
LN 8% or less AU-95% or less Sb 2.5fi
Ge 7% or less Sn 3.5% or less Zt
5.5% or less Hf 5.5% or less Cu 3.5%
Below 8 2.0% or less C4% or less Ca8% or less M
g 8% or less 8d8% or less 01chi or less P
3.5% or less Within the composition of the permanent magnet alloy mentioned above, characteristics superior to the magnetic q# property (BH) MAx4MGOa of conventional hard ferrite formation can be obtained.

According to the present invention, magnetic properties and <K (BH)MA
) 1 is improved.

〔Example〕

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

Comparative Example 1 Electrolytic iron with purity of 99.9wt and 99.0wt as raw material
%B right and b as l[[99,7wt% or more Nd
Using a composition (atomic Q) of 13%Nd-7%B-remaining F
Weigh and inert gas (Ar) to obtain the final sintered body of e.
) to obtain an alloy ingot. Using an alloy ingot di-3-crusher, Brown mill, and jet mill, Ca4) (20KOe
) Middle Tee G7. shape.

A molded body was obtained. The obtained molded body is true! 2! (10-
Sintering was carried out at 1110°C for 2 hours in a
It was quickly cooled to warm temperature. Next, as shown in Figure 3, ICAr gas (
Conventional aging treatment at room temperature (atmospheric pressure)
) to 700°C x 2 hours at a constant temperature of 700°C for 2 hours.
After processing to a size of 0 x 10 x 10 m), the magnetic properties were measured.

The results are shown in Table 1 as shown in 11kLIK (BH) M 31, 5 MGOc t' az ta.

The following is a margin: Table 2 Example 1 As shown in Fig. 1, after the primary aging treatment, heating at 2°C/min from RT to 700'CXIH, cooling at 5°C/min to RT. Heat again at 2°C/min, 69
Everything was carried out in the same manner as in Comparative Example 1, except that after the 0° C. The results are shown as 1st clothes middle block 2. (BH) MAX is 33.1
MGOe was improved by about 5% compared to the conventional method. In addition, after the primary aging treatment, it is processed to the specified dimensions and attached to ai (30
As a result of secondary aging treatment of KOa) L,
It was confirmed that demagnetization and formation of an appropriate oxide film were possible.

Comparative Examples 2 and 3 First holding temperature (T 1') in aging treatment 2 of Example 1
700°C) and secondary holding temperature IJ [(T2x 69
0'C) In comparative example 2, T1■870℃, T2xg5Q
℃, Comparative Example 3 Te! ITI = 370℃, T2
- The same procedure as in Example 1 was carried out except that the temperature was 1360°C. The results are shown as positive 3 (comparative example 2) and 1k4 (comparative example 3) in Table 1. In this case, the magnetic properties obtained are (
BH) MAX21.5 MCK)e.

21.3 MGOe, which is low.

Example 2 In this example, as shown in Fig. 2, Ar gas (atmospheric pressure) was used after sintering.
Intermediate heat treatment (heated at 2°C/min from RT to 1050°C)
After cooling to RT at 25°C/min after X2H,
The aging treatment performed in Example 1, that is, in Ar gas (atmospheric pressure), heating at 2°C/min from T to 700°C
After the primary aging treatment in which the temperature is cooled at 5°C/min to RT, the temperature is heated again at 2°C/min from RT, and after the treatment at 690°C, the secondary aging is cooled at 5°C/min to approximately T. It performs processing. That is, it is the same as Example 1 except that intermediate heat treatment (1050'CX2H) is performed between sintering and aging treatment.

The results are shown as middle floor 5 in Table 1 (BH) MAX
is 34.5MGOe, compared to the conventional method.
Improved by about 10es.

Comparative Examples 4 and 5 Holding temperature (To) in intermediate heat treatment To -1130°C
(Comparative Example 4), To -800°C (Ratio [Example 5)
The results obtained in the same manner as in Example 2 except that 11 changes were made are shown in the first example.
They are shown as Nakaya 6 (Comparative Example 4) and N17 (Comparative Example 5) in the table.

Compared to the conventional method (Comparative Example 1 31.5 MGOe),
Although the method of the present invention is superior (Example 1 33.1 M
31 compared to GOe Example 2 (34.5MGOe)
．． It is low at 8 to 32.5 MGOe.

Examples 3 to 7 The results were obtained in the same manner as in Example 1 (Ar gas, atmospheric pressure) except that the type of atmospheric gas in aging treatment 2 was changed.
Shown in the table. (BH) MAX is 33.2~33.5MG
Oe and characteristic value 21.3-32.5MGO in comparative example
It is much better than e.

〔Effect of the invention〕

The magnetic properties of the permanent magnet alloy obtained by the heat treatment method of the present invention are the maximum energy product (
BH) MAX is extremely large and its industrial value is great.

[Brief explanation of the drawing]

Claims (1)

[Claims] 1. Fe containing R (where R is one or more rare earth elements including Y), B, and unavoidable impurities as essential elements;
An alloy powder with an average particle size of 1 to 50 μm consisting of
After sintering at 00 to 1200℃, the holding temperature is 400 to 8
A method for producing a permanent magnet alloy, which comprises heating to 50°C, holding, and cooling twice or more, and aging treatment to final cooling to 350°C or lower. 2. Aging treatment in vacuum or Ar, He, N_2,
2. The method for producing a permanent magnet alloy according to claim 1, wherein the process is carried out in an atmosphere of one type of gas selected from a mixed gas of N_2 and Ar. 3. After sintering, the permanent magnet is heated and held at a temperature of 850° C. to below the sintering temperature, cooled to 350° C. or below, and then subjected to the aging treatment. Method. 4. Aging treatment in vacuum or Ar, He, N_2,
4. The method for manufacturing a permanent magnet according to claim 3, wherein the method is carried out in an atmosphere of one type of gas selected from a mixed gas of N_2 and Ar.