JP3108946B2 - Manufacturing method of permanent magnet alloy powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an RxT (100- x-
y) Ny (R is at least one of rare earth elements including Y, and T is at least one of Fe, Co, and Ni and is represented by the formula of 5 ≦ x ≦ 20, 2 ≦ y ≦ 30) The present invention relates to a method for producing a permanent magnet alloy powder obtained over a wide temperature range by nitriding a magnetic alloy powder having excellent magnet properties in a nitrogen plasma.

[0002]

2. Description of the Related Art Permanent magnet materials are electric and electronic components that are widely used in large quantities, such as automobile parts, computer peripherals, speakers, and household appliances.

[0003]

In general, SmCo5, Sm
Sm-Co-based and Nd- containing intermetallic compounds such as m2Co17 and Nd2Fe14B and having excellent magnetic properties
Fe-B based permanent magnet materials, speaker, are often used such as a motor, also contributes weight reduction in size increases the electrical and electronic equipment.

By the way, Nd—Fe—B permanent magnet materials have higher saturation magnetization and maximum energy product than Sm—Co permanent magnet materials, and are relatively inexpensive Nd,
Since Fe is used, it is more widely used than Sm-Co permanent magnets. However, since Nd-Fe-B permanent magnet materials also have disadvantages inferior in thermal stability and corrosion resistance of magnet properties, they are not actually used for a wide range of applications.

As described above, permanent magnet materials are used in many electric and electronic devices, and the demand for higher performance of permanent magnet materials for their reduction in size and weight has been increasing in recent years.
The appearance of post-Nd-Fe-B permanent magnet materials is strongly expected.

[0006] Recently, an R2T17NX-based magnetic compound which has a possibility of becoming a post-Nd-Fe-B-based permanent magnet material is disclosed in J. Irish. M. D. Discovered by Coey et al. In particular, Sm2 Fe17 x magnetic compound has a uniaxial crystalline anisotropy, saturation magnetization 15.4KG and Nd2
Although inferior to 16.2KG of the Fe14B magnetic compound,
Curie temperature is about 470 ° C (Nd2Fe14B is about 30
0 ° C.) and an anisotropic magnetic field of about 140 KOe (Nd2F
e14B has a magnetic property of about 70 KOe) which is superior to that of the Nd2Fe14B magnetic compound.

[0007] Further, since the R2T17NX magnetic compound is synthesized by nitriding the mother alloy R2T17 alloy powder, it can be obtained only in powder form, not in bulk form. Further, the synthesis rate of R2T17Nx is difficult due to the low reaction rate in low-temperature nitriding. At a temperature of about 600 ° C., R2T17Nx decomposes into RN and T, so that R2T17Nx having good characteristics is synthesized only in a narrow nitriding temperature range. .

For this reason, R2 by a conventional method such as sintering is used.
It is very difficult to make a T17Nx magnetic compound into a bulk,
It is expected to be limited to applications in powder form, and it has been desired to increase decomposition temperature, stabilize at high temperature, and synthesize in a wider nitriding temperature range as a way to expand applications.

Therefore, the present inventors have obtained RxT (100 -xy) N obtained by nitriding an RT master alloy containing an R2T17-based magnetic compound in a wide range of nitriding temperature in nitrogen plasma.
Good results were obtained for the magnetic material represented by the equation y. That is, according to the present invention, by nitriding the RT master alloy in a nitrogen plasma, the magnetic properties represented by the formula of RxT (100 -xy) Ny having excellent magnetic properties in a wide range of 200 to 700 ° C. It has been found that a material can be obtained. In the nitrogen plasma, the nitridation reaction of the R2T17Nx magnetic compound may be promoted at a low temperature, and the generated energy may be changed at a high temperature.

[0010]

According to the present invention, a rare earth element-transition metal powder is nitrided in a nitrogen plasma to form an RxT (1
00 -xy) Ny (R is at least one of rare earth elements including Y, T is at least one of Fe, Co, and Ni and 5 ≦ x ≦ 20, 2 ≦ y ≦ 30) It is characterized by being represented by

If x in the above formula is smaller than 5, it is difficult to obtain a coercive force, and if x is larger than 20, the saturation magnetization is undesirably reduced. Y is smaller than 2 and 3
If it is larger than 0, it becomes difficult to obtain a coercive force.

[0012]

EXAMPLES (First Example) It was obtained by melting an alloy having a composition of Sm10.8Fe89.2 in atomic percentage. To compensate for evaporation loss during melting, there was a slight excess of Sm at the start of melting.

The obtained alloy having the composition of Sm10.8Fe89.2 was annealed at 1,100 ° C. for 24 hours in an Ar atmosphere. The obtained alloy was roughly pulverized by a disk mill, and further pulverized by a ball mill to an average particle size of 30 μm.
Furthermore, the obtained powder was discharged at a nitrogen pressure of 500 Pa and a voltage between electrodes of 400 V in a nitriding plasma at 200 ° C. to 70 ° C.
Nitrogen was allowed to enter for 1 hour at a temperature of 0 ° C.

As a comparative example, the same powder was added at 200 ° C.
Nitrogen was allowed to enter for 1 hour at ~ 700 ° C and 1 atm of nitrogen.

The magnetic properties of each of the nitrided alloy powders thus obtained were measured using a vibrating sample magnetometer (V, S, M). Table 1 shows the results.

[0016]

[Table 1]

(Second Embodiment) Sm5.9Fe9 is obtained by the same method as in the first embodiment.
An alloy powder having a composition of 4,1, Sm20.7Fe79.3 was obtained. Nitrogen was introduced into the obtained powder at a temperature of 500 ° C. for 1 hour in a nitrogen plasma discharged at a nitrogen pressure of 500 Pa and a voltage between electrodes of 400 V, and Sm5.3Fe84.0N was used.
A nitrided alloy powder having a composition of 10.7 and Sm19.2Fe73.4N7.4 was obtained.

As a result of measuring the magnetic properties of each nitride alloy powder, the powder having a composition of Sm5.3Fe84.0N10.7 had 4πIs = 16.8KG, IHc = 2.3KOe, and Sm19.2Fe73.4N7.4. The powder of the composition had 4 μIs = 11.0 KG and IHc = 3.1 KOe, and both exhibited excellent magnetic properties.

(Third Embodiment) Sm10.8Fe89.2 obtained in the first embodiment.
Nitrogen pressure 500 Pa, interelectrode voltage 4
1 at 550 ° C. in nitrogen plasma discharged at 00V
Nitrogen was allowed to enter for 0 to 120 minutes. Table 2 shows the results of measuring the magnetic properties of each of the obtained nitrided alloy powders.

[0020]

[Table 2]

Fourth Embodiment A raw material alloy powder was obtained in the same manner as in the first embodiment, using Sm, Ce, Pr, Gd, Dy and Fe having a purity of 99.9%. Further, nitrogen was allowed to penetrate the powder in a nitrogen plasma under the same conditions as in the first embodiment. Table 3 shows the results of measuring the magnetic properties of the obtained nitrided alloy powders of each composition.

[0022]

[Table 3]

Fifth Embodiment Using Sm, Fe , Co and Ni having a purity of 99.9%,
In the same manner as in the first embodiment, Sm10.6Fe70.
6Co18.8, Sm10.3Fe79.9Ni9.8
An alloy powder having the following composition was obtained. A nitrogen pressure of 50 is applied to the obtained powder.
Nitrogen was introduced at 550 ° C. for 1 hour in nitrogen plasma discharged at 0 Pa and a voltage between electrodes of 400 V, and Sm
9.3Fe61.9Co16.5N12.3, Sm9.
A nitrided alloy powder having a composition of 1Fe70.7Ni8.7N11.5 was obtained. As a result of measuring the magnetic properties of each nitrided alloy powder, the powder having the composition of Sm9.3Fe61.9Co16.5N12.3 was 4πIs = 15.5KG and IHc = 3.5.
KOe, Sm9.1Fe70.7Ni8.7N1
The powder having a composition of 1.5 is 4πIs = 13.9KG, IHc
= 2.6 KOe.

[0024]

As described above, according to the present invention, by using a method of nitriding a rare earth element-transition metal material in a nitrogen plasma, a rare earth element having excellent magnetic properties in a wide nitriding temperature range from a low temperature to a high temperature can be obtained. A transition metal-nitrogen permanent magnet can be obtained, which can greatly contribute to reduction in size and weight of electric and electronic devices.

Claims (1)

(57) [Claims] An RxT (100 -x-) is characterized in that a rare earth-transition metal powder is nitrided in a nitrogen plasma.
yy) Ny (R is at least one of rare earth elements including Y, and T is at least one of Fe, Co, and Ni and is represented by the formula of 5 ≦ x ≦ 20, 2 ≦ y ≦ 30) Manufacturing method of permanent magnet alloy powder.