JPS58186906A - Permanent magnet and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain composition of metal elements forming a magnet and preparation steps for the same, particularly a rare earth-cobalt system permanent magnet which has excellent magnetic characteristic and a high coercive force and preparation of the same by the quick cooling method for efficiently lowering a high temperature single phase up to a room temperature and combination of such methods. CONSTITUTION:A magnetic alloy having such a composition, in weight percentage, that 20-28% R (one or two kinds of rare earth elements), 1-9% Cu, 14- 40% Fe, 0.5-7% M (one or two kinds selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mn, Mo, W, Si, Al), remainder mainly consisting of Co and containing, as the main elements, an intermetallic compound having the crystal structure of TbCu7 type or Th2Ni17 or mixed crystal structure of them, is fused and the fused said magnetic alloy is quickly cooled to a temperature lower than the room temperature at a cooling rate of 100 deg.C/sec or higher. Thereafter, it is subjected to an aging process for 0.1-500hr within the temperature area of 350- 900 deg.C. As a rare earth element indicated by R, Sm, Ce, Pr, Se, Y, La, Nd, Pm, Eu, Gd, Dy, Ho, Er, Yb, Lu, Tb and Tm etc. can be considered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rare earth-cobalt permanent magnet and a method for combining the same, and more particularly to a rare earth-cobalt permanent magnet with excellent magnetic properties, particularly a large coercive force (lHe), and a method thereof. Regarding the manufacturing method.

[Technical background of the invention and its melting point]

Conventional 8mt Cot? Various compositions of thread permanent magnets have been proposed, but ('Cut part of o)'
e and M (Ti, Zr+ Hft Vt Nbe
Ta, Crs Mn, Mol w.

By replacing K with Si, AI), the coercive force (IHe
'), residual I&magnetic flux density (Br), and maximum energy product ((BH)max) ≠ are intended to improve oxidation resistance. The present invention provides such gm, (Co, Cu,
Fe.

M), relates to the improvement of i-based permanent magnets. Among the above characteristics, (BH) maw and Br are particularly important in applications such as motors, and are desired to be as large as possible, but if IHc does not exceed a certain value (BE)
It is difficult to increase max and Br.

Therefore, it is also necessary to increase Kif and IHc in order to obtain a large-sized permanent magnet of (13H)max and Br.

By the way, 8rn, (('o, Cut Fce M
) It is known that in ty-based magnets, the residual magnetic flux density can be increased by increasing the Fe content or decreasing the Cu content. However, if the Fe content is increased or the Cu content is decreased, the coercive force decreases, so simply increasing the
If the u content is reduced, it is impossible to improve the residual magnetic flux density or the maximum energy product. Therefore, the composition of conventional am, (Co, Cu, Fe, M)ty Ik magnets is determined with the aim of increasing the residual magnetic flux density as much as possible while maintaining a coercive force of K1m above a certain value. Ta. For example, Sml (Co+Cu, F@*M)I described in Japanese Patent Publication No. 55-15096
For y-based magnets, Cu is 5 to 20% by weight and F.2 to ls weight arc. Moreover, in the magnet described in JP-A-52-109191, Cu9 to 13% by weight and Fe 3 to 12% by weight
It is. These compositions are the result of compromising adaptation to the changes in residual magnetic flux density and coercive force that occur with variations in Cu content and Fll content, so they are not necessarily sufficient F.
It was a duck that couldn't stand.

Now, in rare earth-based permanent magnets, especially gmt Co, y-based permanent magnets, in order to improve their magnetic properties, elements other than rare earth elements such as -(Cu) and iron (Li) are used in addition to cobalt (Co). 'e), +*-um (Ti
), zirconium (Zr), hafnium (Hf),
A magnetic alloy containing Nb (Nb), Mn (Mn), etc. is subjected to solution treatment at a high temperature range of 1000°C or higher and lower than the melting point to form a so-called 2-17 type single phase. A method is known in which a bm*CuK-rich phase called a 1-5 type phase is finely precipitated in the 2-17m phase by performing an aging treatment.

On the other hand, in order to further improve the magnetic properties of the permanent magnet, especially IHc, it is necessary to increase the composition ratio of Fe, which is effective in increasing #i and saturation magnetic flux density (Bl).

However, when the F concentration in the magnetic alloy increases,
The range of solution treatment temperatures in the above-mentioned high-temperature range is extremely narrow, and the cooling rate by conventional one-manufacturing methods, especially air cooling, water cooling, or IIi forced gas cooling, which is applied when rapidly cooling magnetic alloys from a molten state. In this case, it becomes difficult to supercool the above-mentioned high-temperature single phase. As a result, it is not possible to obtain suitable magnetic properties and a particularly large Ilc.

In addition, a magnetic alloy is produced by a melting method using high-frequency induction heating means, and then the magnetic alloy is pulverized into a fine powder.
In a manufacturing method in which the fine powder is molded in a magnetic field, the resulting molded body is sintered, and then subjected to solution treatment and aging treatment, after sintering the molded body, a certain amount of Another problem arises in that the cooling rate applied for solution treatment at the same time as sintering must be determined taking into account the thermal shock resistance of the compact.

[Purpose of the invention]

The object of the present invention is to provide a magnetic material with excellent magnetic properties, especially coercive force (
Inc.) provides a large rare earth-cobalt permanent magnet and a method for manufacturing the same.

[Summary of the invention]

The present inventors have developed a coercive force mechanism of a 2-17 type magnet with an 8rrC
Based on the spinodal decomposition in the S-diagram, and the fact that the magnetic alloy phase must be in a single phase state before the spinodal decomposition, the above-mentioned intermelting point can be solved. After extensive research and detailed consideration of the single-phase state, we found that 2
-17 type phase, the single-phase 1iII'1 alloy has three different crystal structures depending on the composition and temperature, namely 'l'b
Cu, type hexagonal, Tht Nl ty type hexagonal and Th
, Zn1. Among these crystal structures, TbCut [! We obtained a new finding that excellent magnetic properties with a large IHc can be obtained by extracting the single-phase and Tht Ni□-type phases from a high temperature state to a temperature at least below the spinodal decomposition temperature, and we have developed the method of the present invention. I have reached the point where I have completed the .

First, SmCu, -sm, (
An example of a high temperature phase diagram of an o,y pseudobinary system is shown in FIG. As is clear from Jin's phase diagram, 8mt Cot exists on the right side of the 1 curve ABCD? It can be seen that the solid phase of is a TbCug II phase, an 'l'hm N11f type phase, and an 'l'ht Znnnn gold phase, depending on the alloy composition and temperature. Moreover, when the composition ratio of Cu decreases (or conversely, the composition ratio of Fe increases), TbCu, gold phase, ThtN1ty
The range of gold phase sFi gradually becomes more and more, and finally TbCu, !
! The Asha disappears, and only the ThtNi and Ma type phases exist.

These TbCu7m I Tht Ni+y II
All of the phases are hexagonal, and when these high-temperature single phases are extracted to a temperature at least below the spinodal decomposition temperature by processing the 11 single phase, the magnetic properties of the obtained particles are improved.

The effects of the present invention are achieved by the combination of the composition of the metal elements constituting the magnet and the manufacturing method, especially the rapid cooling method for effectively drawing out the high temperature single phase at room temperature kn.

That is, the permanent magnet of the present invention has a weight percentage of 20 to 28
%R (represents one or more rare earth elements);
1-9% Cu; 14-40% F; 0.5-7% M (Ti, Zr, Hfe Vt Nb* Ta,
Represents one panicle selected from the group consisting of Cr+Mn, Mo+W+Sit Aj, or ti2111 or more. ); the remainder is mainly C.

The permanent magnet is characterized in that it has a composition consisting of j'bcuy 114 L < is 7b, and is mainly composed of an R1 Co1t intermetallic compound having a crystal structure in which N1ty or a mixture of these types. In the method of the present invention, a magnetic alloy having the above composition is melted, and then the melted magnetic alloy is rapidly cooled to a temperature below room temperature at a cooling rate of 1000°C/sec or more, and then heated at a temperature of 350 to 900°C. 0.1 in temperature range
It is characterized by being aged in brass for ~500 hours.

In the magnetic alloy used in the method of the present invention, the rare earth element represented by R is 8m+ Ce+ Prl 5et
Yt La+ NtL pm, Eue Gd+ Dy
+ Hot gr, yb, Lu+' [b, Ta cram school will be opened. An essential component for forming RFi & Co5t phase, if its content is less than 20% I
)1c does not increase and exceeds 28wt, 13r decreases and (BH)maw also does not increase.
.

It is an element that stabilizes the Ni, y hexagonal crystal) and an element that is effective for 1-spino-unidal decomposition. When the Cu content is 1 weight, it stabilizes the Zn1yll phase, so ll(c does not increase, and if it exceeds 9 weight, gr decreases and (BH) maw also does not increase.

Fe is an effective element for increasing Br, but when its content is less than 14% by weight, Br and (BH) ma
The improvement in
In order to stabilize the nty II phase, IHc is gradually decreased and (B)l) max is also decreased.

M (has the same meaning as above) is similar to Cu,
High temperature phases of magnetic alloys (TbCuvll, Tbv N1ty
It is an element that stabilizes the hexagonal crystal. M content is 0
．． In the case of a 5-weight attack drop, the Th1Zntv type phase comes to be mixed, so the increase in l1ic becomes less noticeable,
When adding 7jusha%, Br decreases and (BH)
The increase in max is also achieved.

In the method of the present invention, first, a magnetic alloy is melted.

Melting is carried out by mixing the powders or lumps of the above-mentioned elements to a predetermined composition ratio, placing the mixture in a quartz container, and then heating it with a high-frequency induction coil; using a curl or a metal heating element. Heating methods such as resistance heating; heating by infrared 11 such as xenon lanthanum; heating by electron beam; and heating by arc discharge are applied. At this time, since rare earth elements are easily oxidized or evaporated, it is necessary to evacuate the entire system and then melt the system in an atmosphere in which an inert gas such as argon is introduced.

Now, the first feature of the method of the present invention is that the magnetic alloy melted by the method described above is rapidly cooled to transform the high temperature phase into TbCu7.
1JJI phase or 'rh, Nt, ll phase is drawn out in a single phase part to room temperature.

High temperature state SIi in Figure 1! As is clear from i1, Fe
As the composition ratio increases (Cu composition ratio decreases), T
Since the range of temperature for incubation treatment of bCu, gold phase, and Thx N1ty type phase is extremely narrow, these TbCuy #I
Since the i-phase, Th, Ni, and gold phases are extracted as a single phase at room temperature Kt, it is understood that K requires an extremely high cooling rate.

Therefore, in the method of the present invention, the above-mentioned TbCu,
In order to extract the ail phase or the ThtNt, II phase, the above-mentioned alloy having a molten state of 11 Vc is jetted onto the rotating surface of a drum or four wheel with good thermal conductivity rotating at high speed, the so-called method. It is preferable to apply a molten metal quenching method.

The cooling rate applied in the method of the invention is usually 1000°C
/sec or more, and if the cooling rate is less than this, solidification segregation occurs, and TbCu, a! I phase or Th
, Ni, it becomes difficult to extract the gold 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, its rotation speed, etc., but the material of the rotating body is usually **
Materials with excellent thermal conductivity such as Ago Cu, Fs, or their alloys, and a rotation speed of 100 r
It is preferable that it is above pm.

In this way, most of the TbCuv ji [phase or T
A thin strip, flake, or powder of a supercooled alloy consisting of h, Ni, and a gold phase is obtained.

The second feature of the method of the present invention is that the supercooled alloy described above is
, flakes, or powders are subjected to aging treatment.

The aging treatment temperature for this dark brown must be in the range of 350 to 900°C, and if it is out of this range, an increase in lHe cannot be achieved. Also, for the same reason, the aging processing time is
It is necessary that the time is in the range of 0.1 to 500 hours.

One example of a preferred aspect of aging treatment in the present invention is aging at 850° C. for 30 minutes, followed by four-stage aging treatment at 100° C. for 1 hour, 2 hours and 24 hours.

A permanent magnet according to the present invention is manufactured using the magnetic alloy thus obtained in accordance with a conventional method. That is, as an example of the method, a method is preferably applied in which the above-mentioned aging-treated material is pulverized into a fine powder, which is magnetically arranged and pressure-molded.

For example, the obtained magnetic alloy is pulverized in a non-oxidizing atmosphere such as nitrogen or argon and liquid ethyl alcohol while preventing the formation of oxides.In this case, the magnet is subjected to IHe aging treatment. Since it is based on the microstructure in the formed alloy, it is preferable to grind to an extent that this structure is not destroyed, that is, to a particle size of 2 to 1 μm. When the particle size is less than 2 μm, the above-mentioned microstructure is destroyed, so IHcif decreases and % or sl
When exceeding o*m, both IHc s Br decrease.

Organic pine paste (for example, nylon dissolved in methyl alcohol) is added and mixed to the obtained fine powder to the extent that it becomes slightly moist, and this is mixed with a non-magnetic material (for example,
10,000 to 30,000 for filling in the golden leprosy of brass
While applying a magnetic field of G to magnetically align the fine powder, press molding is performed at a pressure of 2 to 6 tons/- to form a permanent magnet in the shape of a square.

Further, if necessary, store the above permanent magnet in a water-impermeable flexible container such as plastic or rubber, and store it in a container of 3 to 5 tons.
By applying a three-dimensionally uniform stress by isostatic pressing with on/- pressure, a permanent magnet with no magnetostriction and excellent mechanical strength can be obtained.

The permanent magnet thus obtained is TbCuy ml
Maybe! The main component is a RICOI intermetallic compound having a crystal structure in which these properties are mixed, and it has excellent magnetic properties and especially coercive force.

[Embodiments of the invention]

Examples 1 to 13 Alloy materials having the compositions of Examples 1 to 13 shown in the table were placed in a quartz container equipped with a nozzle at the tip, and melted in an argon atmosphere by high frequency induction heating.

The temperature is maintained at 50℃ higher than the melting point, and the molten alloy is heated to 100O
It was ejected onto the rotating surface of a copper plate 300 m in diameter rotating at rpm. The cooling rate of this rapid cooling process is approximately 10”C/
It was sec. Flaky flakes were obtained.

The crystal structure of this flake was determined using the XMA method. An example of such a diffraction matrix turn is shown in FIG. As is clear from Figure 2, most of one thin section is TbCuy I! It is composed of a hexagonal crystal of the phase, and 7b is located around 2# = 38 to 39 degrees.
The (024') peak of the l Zntv type orthorhombic crystal was hardly observed. That is, in the thin section, Tb
It was found that the Cuy If phase was extracted in a single phase state.

Next, the above flakes were aged at 850°C for 30 minutes, and then aged in four stages at 100°C intervals for 1 hour, 2 hours, and 4 hours 1*. The crystal structure of the obtained flakes was fixed by X-ray diffraction and shown in the table.

Next, this flake was coarsely ground to the extent that it could pass through a 20-mesh Tyler sieve, and then further ground in a mesh mill with an average particle size of 4 μm.
It was made into a fine powder of m. After mixing this fine powder with a 4% nylon-methanol solution, it was filled into a predetermined pressing mold, and
Compression molding was carried out under a pressure of 2 tons/- while applying a magnetic field of 000 oersted.

This green compact was placed in a rubber container and subjected to hydrostatic pressing at 5 tons/csj.

Residual magnetic flux density (Br) and coercive force (IH) of the obtained permanent magnet
c), Maximum energy product ((BH) maw) Table Comparative Examples 1 to 3 For alloys with compositions of Comparative Examples 1 to 3 shown in Table
After creating a thin section using the molten metal quenching method under the same conditions as in case 1-13, (b); Aging treatment at 980'C for 30 minutes, followed by 4 steps of 1 hour, 2 hours, and 4 hours at 100 degrees Celsius. Aging treatment, (c); Aging treatment at 750°C for 750 hours (
d); After aging treatment at 300°C for 500 hours, this flake was coarsely and finely pulverized in the same manner as in Examples 1 to 13 to obtain a fine powder with an average particle size of 4 μm, and in the following Examples 1 to 13 A permanent magnet was obtained under the same conditions.

Comparative Examples 4-8 For the alloys having the compositions of Comparative Examples 4-8, the alloy material 20
I was heat-treated at 1200° C. for 11 hours in Alco, followed by rapid cooling at a cooling rate of 1000° C./min. When the alloy material was subjected to XS diffraction after cooling, the diffraction pattern had a characteristic 'r around Fi2θ=38 to 39 degrees.
h, zntt-type orthorhombic (024') peak was exhibited.Then, this alloy was subjected to the same aging treatment as in Examples 1 to 8, and then crushed and compacted in the same manner as in Examples 1 to 8, and then permanently I used it as a magnet.

Comparative Examples 9-23 For alloys having the compositions of Comparative Examples 9-23, Examples 1-1
Permanent magnets were used in case 3 and under conditions.

Regarding the above comparative examples, composition, manufacturing conditions, crystal structure, Br
s Inc, (BH) max is also listed in the table.

2 [Effects of the Invention] As described above, the method of the present invention can produce rare earth permanent magnets with large IHc even if the F composition ratio is large (Cu composition ratio is small), so its industrial value is high. Furthermore, the obtained permanent magnet is useful because it has superior machinability compared to magnets produced by conventional sintering methods.
tl! In this invention, 8m, Co, 7b Cuy in the phase
Since the type phase metal phase ThtNi1g type phase is extracted as a single phase metal phase, the composition ratio of expensive rare earth elements and CO can be reduced, and the obtained magnet can be made inexpensive. Another advantage is that it can be manufactured without considering the thermal shock resistance mentioned above.

[Brief explanation of drawings]

FIG. 1 is a high-temperature phase diagram of the am Cm, -8fl1mCOsv pseudo-binary system, and FIG. 1g2 is an example of the X-ray diffraction pattern of a thin piece according to an example of the present invention.

Claims (2)

[Claims] (1) In terms of weight percentage, RCs of 20-2B arc represent one or more elements. );l~9-Cu;1
4-40% Fe; 0. -5~7 Ill's M (
Ti, Zlfj V, Nba Tie Cr, M
n# Mo1W, 81. Represents one or more species carried by the group consisting of Aj. ); the remainder is mainly C. It has a composition consisting of ThCuy, TbtNi, type, or a crystal structure in which these types are mixed &CO1? A permanent magnet characterized by a magnet whose main component is an intermetallic compound. (2) R of 20 to 28 (representing one or more rare earth elements) Cu of 11 to 9 in weight percentage; 14
% of ~40%; 0.5-7% M (Ti, Zr
, HL Vs Nb, Tbt Or, Mn, m
Represents one or more types selected from the group consisting of olwlSt, M. ); Melt a magnetic alloy in which the remainder mainly consists of CO, then 1. Rapidly cool the molten magnetic alloy to a temperature below room temperature at a cooling rate of 1000°C/reduction or more, and then cool it in a temperature range of 350 to 900°C. A method for producing a permanent magnet, characterized by subjecting it to aging treatment for 0.1 to 500 hours.