JPS5886706A - Manufacture of permanent magnet - Google Patents

Abstract

PURPOSE:To form a permanent magnet having excellent magnetic characteristics by a method wherein a magnetic alloy composed of rare-earth elements, cobalt, etc. is melted and then cooled down rapidly so that it has a prescribed crystal structure. CONSTITUTION:A magnetic alloy composed of one or two or more kinds of rare- earth elements and other elements such as cobalt is melted. This melted magnetic alloy is cooled down rapidly, and thereby a TbCu7 or Th2Ni17 type phase is picked out in a single-phase state of a 2-17 type crystal structure from a high- temperature phase down to a room temperature. Next, aging is applied in the temperature ranging from 350 to 900 deg.C, and thereby a 1-5 type phase is educed in a 2-17 type phase. By this method, a permanent magnet having excellent magnetic characteristics and, in particular, having a large coercive force can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a rare earth-cobalt permanent magnet, and more particularly, to a method for producing a rare earth-cobalt permanent magnet, which has excellent magnetic properties, especially magnetic retention force (IHo
The present invention relates to a method for producing a rare earth-cobalt permanent magnet having a large value.

Conventionally, in the production of rare earth-cobalt permanent magnets, magnetic alloys with varying compositions consisting of at least 18 of rare earth elements and at least 1111 of other elements have been prepared using, for example, open-wave induction heating means. The magnetic alloy is prepared by a melting method, and then the magnetic alloy is crushed into a fine powder, the fine powder is compacted in a magnetic field, and the resulting compact is sintered, followed by solution treatment and aging treatment. A manufacturing method called
9191, Japanese Patent Publication No. 55-r5096), ■ A magnetic alloy prepared by the melting method is subjected to solution treatment and then aging treatment, and then crushed to make a fine powder.Finally, this fine powder is magnetically (See Japanese Patent Application Nos. 50-59884 and 1982-13070)
etc. are known.

Among the methods described above, method (■) produces a permanent magnet with excellent magnetic properties, but the whole is hard and brittle, so machinability is desired and it is not suitable for manufacturing magnets that require dimensional accuracy. Not suitable. In addition, the method (2) has the disadvantage that it is superior in terms of workability, but it is inferior in magnetic properties. Both methods also have the economical disadvantage that the manufacturing cost is high because the alloy components contain large amounts of expensive rare earth elements and cobalt.

Now, in order to improve the magnetic properties of cloth-based permanent magnets, especially 5nuCO+y-based permanent magnets,
c. Elements other than rare earth elements include copper (Cu), iron (Fe), titanium (Ti), norconium (Zr), hafnium (Hf), and niobium (N) in addition to cobalt (co).
b) A magnetic alloy containing manganese (KIN) or the like as a composition component is subjected to a generalization treatment at a high temperature range of 1000°C or above and below the melting point to form a single phase state with a so-called 2-17 type crystal structure, and then 2-1 above after applying the prescribed aging treatment.
7a! ! Among the phases, S+r+, which is called the 1-5 type phase,
A method of finely precipitating a CuVC-rich phase is known.

On the other hand, in order to improve the magnetic properties of a permanent magnet, particularly IHO, it is necessary to increase the effective composition ratio of Fe in the alloy to increase the saturation magnetic flux density (Bs).

However, when the Fe concentration in the magnetic alloy increases,
The range of solution treatment temperatures in the above-mentioned sieve temperature range is extremely narrow, and conventional manufacturing methods, especially the cooling speeds of air cooling, water cooling, or forced gas cooling applied when rapidly cooling magnetic alloys from a molten state, do not exceed the above range. high temperature single
It is difficult to supercool the phases below the two-phase decomposition temperature (the spinodal decomposition temperature). As a result, suitable magnetic properties,
In particular, it is not possible to obtain a large IHO. Also, α
) method also has the problem that the cooling rate applied for electrification treatment after forming and sintering the shaped body must also be determined by taking into account the thermal shock resistance of the shaped body. arise.

The present inventors have discovered that the sharpening force mechanism of the 2-17 type magnet is made of SmCu.
In order to solve the above problems, we rely on the spinodal decomposition in the a-8m2Copy pseudo-binary system phase diagram and the fact that the magnetic alloy phase before the spinodal decomposition must be in a single phase state. After extensive research and detailed examination of the single phase state, we found that the single phase state of 2-17 phase has three different crystal structures depending on the composition and temperature of the alloy: TbCuy hexagonal, Th2N
Take i+y type hexagonal crystal and Thg Zr1t type orthorhombic crystal,
Furthermore, among these crystal structure phases, the TbCu7 type phase and the ThN1ty m! The method of the present invention was completed based on the new finding that excellent magnetic properties with a large IHO can be obtained by extracting the phase as it is from a high-temperature phase state to a temperature at least below the spinodal decomposition temperature in a single phase state. reached.

First, SmCu, -8mz C, discovered by the present inventors
An example of a high-temperature phase diagram of the o17 pseudobinary system is shown in Figure 1. As is clear from this phase diagram, the solid phase of Sm2Co+y existing on the right side of the curve
It can be seen that it has a Zr1+y type phase. In addition, the composition ratio of Cu decreases (or conversely, the composition ratio of Fe increases).
Then, the solution treatment temperature range of the '1'bCu7 type phase and the ThxNj+y type phase gradually narrows, and finally the TbCuy type phase disappears and only the narrow ThzNi+y type phase exists.

Both of these TbCuy type and Th heavy N1ty type phases are hexagonal, and if these high-temperature single phases are subjected to single-phase treatment and extracted to at least the spinodal decomposition temperature or below, the resulting alloy The magnetic properties of are improved.

The present invention is based on the above findings, and the present invention is based on the above findings.
It is an object of the present invention to provide a method for producing a rare earth-cobalt permanent MB with a high O content.

The method of the present invention involves melting a magnetic alloy consisting of at least tm of a rare earth element and at least one other element; rapidly cooling the melted magnetic alloy to form a crystal structure of TbCu7 type or ThzNitt type. - The 17-type high-temperature phase is drawn out to room temperature; then, an aging treatment is performed in a temperature range of 350 to 900C to finely precipitate the 1-5 type phase in the 2-17 type phase. It is.

In the method of the present invention, first, in order to make it a conventional method, Sm
, Pr, Ce, Sc, Y, La, Nd,
Pm, Eu, Gd, Dy.

A magnetic alloy consisting of one or more than 2s of rare earth elements such as Ho, Er, Yb, Lu, Tb, and Tm and other elements is melted. Here, other elements are Co, F
e, Cu, Mn.

The main component is 1, 11, or 2 or more of Cr, Ni, etc., but in order to improve the magnetic properties, Ti, Zr, etc.
.

Transition metals such as Hf, Nb, Ta, W, Au,
Precious metals such as Pt, Zn, In, Sn, S
A low melting point metal such as Be.

Periodic law & llA group metals such as Mg, B, A1.8
1. Te.

It is preferable to add a semimetal such as C or a semiconductor element.

Bath melt, row on top +! Powders or lumps of rare earth elements and other necessary elements are blended to a predetermined composition ratio, placed in a quartz container, and then heated with a high-frequency induction coil; carbon or metal Heating methods include resistance heating using a heating element; heating by infrared rays of xeno-nolan f#; heating by electron beam; and heating by arc radiation. At this time, since rare earth elements are easily oxidized or evaporated, it is necessary to evacuate the entire system and then melt it in an atmosphere in which an inert gas such as argon is introduced into the system. The feature of TbCuy is that the magnetic alloy melted by the method described above is rapidly cooled and the high temperature phase is converted to TbCuy.
The purpose is to extract the mold phase or ThaNiry type phase to a single phase illumination to room temperature.

As is clear from the high-temperature phase diagram in Fig. 1, as the Fe composition ratio increases, the CCuff1g ratio decreases) and the TbC
A of the target temperature for u7 type phase and Tb2Ni+y type phase
Since the IL range is extremely narrow, these TbCu7 type phases,
It can be seen that an extremely high cooling rate is required to extract the Th2 Ni17 type phase to room temperature in a single phase state.

Therefore, in the method of the present invention, TbCu
Type 7 or Th, Ni,? In order to extract the pattern,
It is preferable to apply the so-called bath water quenching method, which is a method in which the molten H1 alloy is jetted onto the rotating surface of a drum or roll with good thermal conductivity that rotates at a screening speed.

The cooling rate applied in the method of the invention is typically 1000c
/see or higher, and if the cooling rate is lower than this, solidification segregation occurs and the TbCu7 type phase or 'l'h2
It becomes difficult to extract the Ni+y type phase as a single phase to room temperature, which does not meet the purpose of the present invention. This cooling rate is determined by the material of the rotating body, the rotation speed, etc., but if the material of the rotating body is
Materials with excellent thermal conductivity such as Ag, Cu, Fe, or their alloys, and a rotation speed of 100 rpm
It is preferable that it is above.

In this way, most of the TbCuy [phase or Th*
Ribbons and flakes of supercooled alloys composed of Ni+y type phase (
flakes) or powder are obtained.

The second feature of the method of the present invention is that the ribbon, flake, or powder of the above-mentioned supercooled alloy is subjected to an aging treatment to finely precipitate the 1-5 type phase in the 2-17 type phase.

The aging treatment temperature at this time is in the range V of 350 to 900C.
It is necessary to have a certain value of C, and if it is outside this range, the IHO cannot be increased. The aging treatment time is not particularly limited, but it is preferably about 0.1 to 100 hours.

One example of a preferred aspect of aging treatment in the present invention is aging at 850C for 30 minutes, followed by four-stage aging treatment at 100C intervals for 1 hour, 2 hours, and 4 hours.

The permanent magnet according to the present invention is manufactured by a conventional method using the ribbon, flake, or powder thus obtained. That is, as an example of the method, a method of pulverizing the above-mentioned aging-treated material into fine powder, magnetically arranging the fine powder, and press-molding the fine powder is preferably applied.

As described above, even if the method of the present invention has a large Fe composition ratio and a low Cu composition ratio, it is possible to produce a rare earth permanent magnet with a large IHO, so its industrial value is extremely large. Furthermore, the obtained permanent magnet is useful because it has superior machinability compared to magnets produced by conventional sintering methods. Furthermore, since the present invention extracts the T b CuT type phase or ThzNity type phase from the SmzCo+7 phase in a single phase state, the composition ratio of expensive rare earth elements and CO can be reduced, and the resulting permanent magnet is inexpensive. Become. Another advantage is that it can be manufactured without considering thermal shock resistance as described above.

The method of the present invention will be explained below based on examples.

Example 1) Production sample 1 of permanent magnet: Sm 25.4 mm%, Fe 30.0
Weight %, Cu 3.0 weight %, T 12.0 weight %, balance C.

An alloy material consisting of was placed in a quartz container equipped with a nozzle at the tip and melted in an alcohol atmosphere by high frequency induction heating.

The above bath alloy held at 1350°C was heated at 11000r
It was ejected onto the rotating surface of a roll made of copper with a diameter of 300φ rotating at speed p. The cooling rate was approximately 10'C/see. Flaky flakes were obtained.

The crystal structure of this thin piece was investigated by XS diffraction method. The diffraction pattern is shown in Figure @2. As is clear from Fig. 2, the flakes are mostly composed of hexagonal crystals of TbCu7 type phase, and 'l'hl ZnIy type orthorhombic crystals around -38 to 39 degrees 2θ (024). +2
) Almost no peak was observed. That is, it was confirmed that the TbCuty m phase was extracted in a single phase state in the thin section.

Next, the above flakes were aged at 8500 for 30 minutes, and then aged at 100
A four-stage aging treatment was performed at intervals of 1 hour, 2 hours, and 4 hours at °C.

The aged flakes were then coarsely ground to the extent that they could pass through a 20-mesh sieve, and then ground in a jet mill with an average particle size of 4 μm.
It was made into a powder. After mixing this fine powder with 4% nylon-methanol fga, it was filled into a predetermined pressing mold and
．． Apply a magnetic field of 000 ersteg 2 ton/
Pressure molding was carried out at a pressure of -. This green compact was placed in a rubber container and further subjected to isostatic pressing at 5 tons/aj. The obtained permanent magnet was designated as Sample 1.

Sample 2: An alloy material 20F with the same composition as Sample 1 was heat-treated at 1200C for 1 hour in argon, and then heated to 1000C/
It was rapidly cooled at a cooling rate of -.

After cooling, the alloy material was analyzed by X-ray diffraction, and the diffraction/4' turn showed a characteristic Thx Zn1t-type orthorhombic (024) peak around 20-38 to 39 degrees. .

Next, this alloy was subjected to the same aging treatment as Sample 1, and then crushed and compacted in the same manner to obtain a permanent magnet. This was designated as sample 2.

Sample 3: Sm 13.5 weight kk%, Cet 2.8
11[mm%, Fe25.0 Mm%, Cu2.6 heavy weight%, Mn1.0 weight-1%, 'rt i, o 1%, the balance was except that an alloy material consisting of CO was used. Well,
A permanent magnet was manufactured under the same conditions as for sample 1. This was designated as sample 3. Note that the X-ray diffraction/lean analysis of the obtained thin section showed a typical TbCu7 type pattern.

Material 1: A permanent magnet was manufactured under the same conditions as Sample 2, except that the composition of the alloy material was the same as that used in Sample 3. This was designated as sample 4.

Sample 5: Pr25.7 heavy lid%, Fe28. OX amount%
, Cu2.0) [mm%, Nb l , 0 wt%, Zr
A permanent magnet was manufactured under the same conditions as in the case of Sample 1, except that an alloy material consisting of t, Ol [mm%, stt, o*electron%, and the balance was CO was used. This was designated as sample 5.

Sample 6: A permanent magnet was manufactured under the same conditions as Sample 2, except that the alloy material was the same as the composition used in Sample 5, and this was designated as Sample 6. Sample 7: Ce2B , 0% by weight, Fe 25.0 *
mm%, Cu3.0]! L amount J16, V l
, 0 weight t%, Ni 1.0jfet%, balance or Co
A permanent magnet was manufactured under the same conditions as Sample 1, and was designated as Sample 7, except that an alloy I material obtained from the above was used.

Trial 08: A permanent magnet was manufactured under the same conditions as Sample 2, except that the composition of the alloy material was the same as that used in Sample 7, and this was designated as Sample 8.

Among the above samples, Samples 1, 3, and 5.7 were obtained by the method of the present invention, and Samples 2, 4, and 6.8 were comparative examples.

2) Magnetic properties of each sample Accordingly, the residual magnetic flux density, coercive force, and maximum energy product of each sample were measured. The results are shown in the table.

[Brief explanation of the drawing]

Is the 1i81 diagram SmCua -3m2 COI? The high-temperature phase diagram of the pseudo-binary system, FIG. 2, is the X-diffraction pattern of a thin piece of sample 1 in the example. Cu (w%) 2θ □

Claims (1)

[Claims] A magnetic alloy consisting of at least one rare earth element and at least 1 m of other elements is melted; the molten #magnetic alloy is rapidly cooled so that the crystal structure is
U7 type or ThtNi+ type 2-17! ! ! The high-temperature phase is drawn out to room temperature; then, an aging treatment is performed in a temperature range of 350 to 900 C, and #
A method for manufacturing a permanent magnet characterized by finely precipitating a K1-5 type phase in a 2-17 type phase.