JP3303044B2 - Permanent magnet and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth cobalt magnet, and more particularly, it mainly comprises an R (where R is at least one rare earth metal containing Y) -cobalt intermetallic compound, The main components are Cu, Fe and Zr
The present invention relates to an R ₂ Co ₁₇ precipitation hardening type permanent magnet having a specific composition added.

[0002]

2. Description of the Related Art It has long been well known that many intermetallic compounds exist between a rare earth metal and Co.
It has been pointed out that among the metal compounds, a ferromagnetic compound centered on RCo ₅ has an extremely large crystal magnetic anisotropy and a high saturation magnetic flux density, and thus is an excellent permanent magnet. This has led to the commercialization of rare earth cobalt magnets, which have much higher properties than conventional magnets, through much research. Of RCo ₅ alloys, in particular having a high coercive force that leads to 30KOe in SmCo _{5 (i} H _c), the maximum energy product {(BH) m} also reached 25 MGOe.

On the other hand, an R ₂ Co _17- based alloy, which is a precipitation hardening type permanent magnet, has a low ratio of R to Co, is inexpensive, has a high saturation magnetic flux density, and has a high energy product. Since then, many studies have shown that Cu, Fe,
In the specific composition to which Zr is added, a characteristic of 30 MGOe is obtained at the maximum energy product. For example, Tokuho 1
No. 46575 (hereinafter referred to as Conventional Example 1) states that
4 to 28 wt% rare earth metal R, 1 to 5 wt% copper C
u, 1-35 wt% iron Fe, 0.5-6 wt% (M
= Nb, Zr, Ta, Hf, Ti, V), and 22-7
A precipitation hardening type permanent magnet containing 3.5 wt% Co and having a cell structure with a cell-to-cell distance of 500 Å or more is shown as a microstructure. In addition, 2-5
No. 2413 (hereinafter referred to as Conventional Example 2) discloses Ce-
Co-Cu-Zr-Fe system, Ce-Sm-Co-Cu-
In a Zr—Fe-based permanent magnet (where Sm is 80% or less of the total weight of Ce and Sm), a zirconium-containing phase exists parallel to the c-plane of the crystal at an average distance of 5000 Å or less from each other. Magnets are shown.

[0004]

However, R ₂ CO ₁₇
The RCo ₅ phase and the R ₂ Co ₁₇ phase are separated into two phases by aging, and are magnetically hardened to exhibit preferable magnetic properties.
It is known that R ₂ Co ₁₇ alloy has a cell structure as a fine structure. In the cell structure, the boundaries between cells are clearly distinguished, and analysis results of electron beam diffraction patterns show that the inside of the cell has 2/17 phase of rhombohedral structure and that the cell boundary has 1/5 phase of hexagonal structure. Have been.

In Conventional Example 1, it is known that the coercive force of the R ₂ Co ₁₇ alloy is caused by the size of the cell structure. In a system in which Cu, Fe and Zr are added to R ₂ Co ₁₇ , the aging time is prolonged and the cell size is coarsened. It is said that the coercive force decreases with an increase in the cell diameter when the length is increased. The value of this limit has been shown to be around 6000 angstroms. However, in Conventional Example 1, no mention is made of the phase structure other than the RCo ₅ phase and the R ₂ Co ₁₇ phase.

In the R ₂ Co ₁₇ -based alloy containing Ce as an essential component in the conventional example 2, a zirconium-containing phase is described, and the average distance between the zirconium-containing phases parallel to the c-plane whose characteristics are deteriorated is described. The upper limit is 5000
Angstrom. However, only the phase structure of the zirconium-containing phase within the composition range containing Ce is described, and no details of the phase structure not containing Ce or other phase structures are given.

[0007] Therefore, the technical problem of the present invention is a rare earth cobalt-based precipitation hardenable magnet composed mainly of Sm as the rare earth, consider the microstructure, a permanent magnet makes it possible high coercivity, and high energy product It is to provide a manufacturing method thereof.

[0008]

According to the present invention, 23 to 27% of R (where R is at least one of rare earth metals including Y) and 3 to 6% (not including 6) are expressed by weight percentage. ) C
An alloy having a composition consisting of u, 10 to 25% Fe, 1.5 to 4% Zr, and the balance substantially Co, wherein the alloy contains an intermetallic compound mainly composed of rare earth cobalt. With cell center distance of 500 angstroms
A microstructure having a cell structure of less than or equal to the cell size, wherein in the cell structure, the inside of the cell has a main component phase of R ₂ Co ₁₇ , and the cell boundary has a phase of RCo 5 as a main component and a crystal of an intermetallic compound. And a microstructure surrounded by two phases with a Zr-containing plate-like phase parallel to the c-plane.

The reasons for limiting the composition of the permanent magnet of the present invention are as follows. When the R content of at least one of the rare earth metals containing Y exceeds 27 wt%, the saturation magnetic flux density (Br) decreases. The R is a constant coercive force is less than 23wt% _{(i H c)} is obtained, because the squareness of demagnetization curve is deteriorated deteriorated magnetic properties. In addition, Cu
Amount lower _i H _c is less than 3 wt%, because the Curie point and the Br decreases becomes more than 6 wt%. Also, F
As for the amount of e, Br is reduced when the content is less than 10 wt%, and 2
5 exceeds wt% when _i H _c is lowered. Further, the outside Zr amount is 1.5~4wt% _i H _c and energy product {(BH) m} is lowered.

The permanent magnet of the present invention having such a composition has a cell structure whose fine structure can be observed with a transmission electron microscope.
_{It has} a main phase of ₂ Co ₁₇ and the cell boundary is RCo ₅
And a Zr-containing plate-like phase, and has a microstructure surrounded by two phases, and the distance between cell centers of adjacent cells is less than 500 Å. Preferably, the distance between the cell centers is in the range of 200 to 400 angstroms.

In the present invention, whether or not the above-described cell structure is provided can be easily observed and verified by a scanning electron microscope or a transmission electron microscope.

The permanent magnet of the present invention having such a configuration is manufactured as follows. Each raw material is blended so as to have the composition shown above, and melted by a high-frequency melting furnace in a vacuum of 1 × 10 ⁻² Torr or less to obtain a mother alloy ingot. Next, the obtained master alloy ingot is roughly pulverized, and further finely pulverized in an inert atmosphere using a jet mill or the like to obtain a powder having an average particle diameter of 1 to 5 μm. This powder is 7 ~
Vertical to the magnetic field in a magnetic field of 22KOe, or press formed shape <br/> by pressure of 0.5 to 2.0 t / cm ² in a parallel direction. Thereafter, the molded body is sintered at a temperature of 1150 to 1250 ° C. in a vacuum of 1 × 10 ⁻² Torr or less, or in an inert atmosphere, or an atmosphere of a combination of these. The solution treatment is also performed at a temperature lower by 10 to 50C. After the solution treatment, it is rapidly cooled at a cooling rate of 60 ° C./min or more. After quenching, 1 × 10 ^-2 To
700 to 87 in a vacuum of rr or less or in an inert atmosphere
Aging treatment is performed by heating and holding at a temperature of 0 ° C. for 1 hour or more.

In the present invention, these melting, pulverizing, sintering, and solution treatments are all performed in a vacuum or in an inert atmosphere, so that the carbon content of the alloy is 700 ppm or less and the oxygen content is 700 ppm or less. To 3000 ppm or less, and a permanent magnet having excellent magnetic properties can be obtained.

Magnetic hardening is performed by such a manufacturing process, and the permanent magnet of the present invention is obtained.

Incidentally, the permanent magnet of the present invention can be widely used for watches, electric motors, instruments, communication devices, computer terminals, speakers, video disks, and other various components.

[0016]

In the present invention, in addition to the cell structure seen in the microstructure of the precipitation hardening type magnet, a Zr-containing plate-like phase is precipitated parallel to the c-plane of the crystal of the rare earth cobalt intermetallic compound.
A high coercive force and a high energy product can be obtained by providing not only the pinning effect of the domain wall at the cell boundary but also the pinning effect of the domain wall by the plate-like phase.

[0017]

Embodiments of the present invention will be described below.

Example 1 First, as shown in Table 1 below , Sm, Ce, Cu,
The respective raw materials were blended so as to be alloys of six kinds of compositions of Fe, Zr, and Co, and were melted by a high frequency melting furnace in a vacuum of 1 × 10 ⁻² Torr or less to obtain six kinds of mother alloy ingots. , These master alloy ingots are roughly pulverized and finely pulverized in an inert atmosphere using a jet mill to obtain an average particle size of 4 μm.
m were obtained. This powder was dried under a magnetic field of 15 KOe.
By pressure of 0 tons / cm ² to obtain a press-formed shape molded body. The molded body obtained in this manner is 1 × 10 ⁻² T
In vacuum at or below orr and in an inert atmosphere, 1
Sintering at a temperature of 200-1250 ° C, then 1180
Solution treatment was performed at 1230 ° C., and rapid cooling was performed at a cooling rate of 100 ° C./min. After quenching, 800 in an inert atmosphere
Isothermal aging treatment was performed by heating and holding at a temperature of 300 ° C. for 300 minutes.

Observation of the six kinds of magnets thus hardened by a transmission electron microscope revealed that the permanent magnets had a cell structure as a fine structure, the inside of the cell had an R ₂ CO ₁₇ phase, and the cell boundary was It was confirmed that it had a microstructure surrounded by two phases of the RCo ₅ phase and the Zr-containing plate-like phase. When the magnetic properties of each permanent magnet material were measured, the results shown in Table 1 below were obtained.

[0020]

[Table 1] As is apparent from Table 1, the permanent magnet according to the first embodiment of the present invention, Br for practical use, i H _c, it can be seen that with the _(BH) m.

Example 2 Sm 25.9 wt%, Cu 4.5 wt%, Fe 15.0
In the same manner as in Example 1, melting, pulverizing, forming, and
Shape , sintering and solution treatment were sequentially performed.

Next, aging treatment was performed in an inert atmosphere at an isothermal aging temperature of 800 ° C. within the range of five types of isothermal aging time shown in Table 2 below, a minimum of 6 minutes and a maximum of 900 minutes. The results are shown in Table 2 below.

[0023]

[Table 2] Next, using a transmission electron microscope equipped with an energy dispersive X-ray analyzer, the microstructures of the test materials having different coercive forces were observed, and the Zr-containing plate-like phase was identified. It is confirmed that it has a cell structure as a microstructure, the cell interior has an R ₂ Co ₁₇ phase, and the cell boundary has a microstructure surrounded by two phases of an RCo ₅ phase and a Zr-containing plate-like phase. Was done.

FIGS. 1 and 2 show microstructure photographs (a-plane of the crystal) of the permanent magnets of the test materials 9 and 11 according to the present invention, respectively.
The nanostructure photographs showing the lattice image at that time are shown in FIGS. 3 and 4, respectively. The distance between the cell centers of adjacent cells is 1
00 to 400 angstroms. It can be seen that there is coercivity _i H _c is also largely related with the increase of the isothermal aging time. The Zr-containing plate-like phase is perpendicular to the c-axis direction,
There are many parallel to the plane. The results of the energy dispersive X-ray analysis of the Zr-containing plate phase and the R ₂ Co ₁₇ phase inside the cell are shown in FIGS. 5 and 6, respectively.

As shown in FIG. 5, a large amount of Zr is detected from the portion where the Zr-containing plate-like phase exists, but almost no Zr is detected from the R ₂ Co ₁₇ phase in the cell shown in FIG. .

(Example 3) Sm 25.7 wt%, Cu
4.3 wt%, Fe 14.9 wt%, Zr 3.0 wt%
The alloy having the composition consisting of Co and the balance Co was subjected to melting, pulverization, molding, sintering, solution treatment, and aging treatment in the same manner as in Example 1. The gas content of each permanent magnet material was measured. The results are shown in Table 3 below together with the magnetic properties.

[0027]

[Table 3] As shown in Table 3, the permanent magnet according to Example 3 of the present invention has a carbon content of 700 ppm or less and an oxygen content of 3000 pp.
m when: Br for practical use, _i H _c, show the (BH) m, it can be seen that a very high squareness ratio.

(Example 4) Sm 25.8 wt%, Cu 4.5 wt%, Fe15.0
wt%, Zr3.0 wt%, and the balance of Co, the alloy was melted, pulverized and formed in the same manner as in Example 1.
Shape , sintering and solution treatment were sequentially performed. Next, the quenching after the solution treatment was performed by using five types of cooling rates shown in Table 4 below.
The test was performed within a range of 30 ° C. to 300 ° C./min. After quenching, an isothermal aging treatment was performed by heating and holding at 800 ° C. for 300 minutes in an inert atmosphere. The results are shown in Table 4 below.

[0029]

[Table 4] Permanent magnets according to a fourth embodiment of the present invention as a result of the above Table 4 shows Br subjecting quench rate after the solution practically 60 ° C. / min or more when, _i H _c, the (BH) m, It turns out that it shows a very high squareness ratio.

[0030]

As described above, the present invention has a cell structure as a fine structure by quenching after melting, pulverizing, sintering, and solution treatment, and performing isothermal aging. It has a main phase of R ₂ Co ₁₇ and the cell boundary is RCo
Provided is a permanent magnet having a microstructure surrounded by two phases of a phase containing ₅ as a main component and a Zr-containing plate-like phase, and having excellent magnetic properties such as a high coercive force and a high energy product, and a method for producing the same. Became possible.

[Brief description of the drawings]

FIG. 1 is a transmission electron micrograph showing a metal structure of a permanent magnet having a fine structure according to Example 2 of the present invention.

FIG. 2 is a transmission electron micrograph showing a metal structure of a permanent magnet having a fine structure according to Example 2 of the present invention.

FIG. 3 is a transmission electron micrograph showing a metal structure for explaining a nanostructure of the permanent magnet of FIG. 1;

FIG. 4 is a transmission electron micrograph showing a metal structure for explaining a nanostructure of the permanent magnet of FIG. 2;

5 is an energy dispersion analysis diagram of the Zr-containing plate-like phase of the permanent magnet of FIG. 1 and the R ₂ Co ₁₇ phase inside the cell.

FIG. 6 is an energy dispersion analysis diagram of the Zr-containing plate-like phase of the permanent magnet of FIG. 2 and the R ₂ Co ₁₇ phase inside the cell.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-50441 (JP, A) JP-A-6-17184 (JP, A) JP-A-58-139406 (JP, A) 52413 (JP, B2) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01F 1/032-1/08

Claims (4)

(57) [Claims] (1) a weight percentage of 23 to 27% of R (R is at least one of rare earth metals including Y) and 3 to 6%
(Excluding 6) is an alloy composed of Cu, 10 to 25% of Fe, 1.5 to 4% of Zr, and the balance substantially Co, and the alloy is mainly composed of rare earth cobalt. Contains an intermetallic compound and has a cell center distance of 500
Microstructure with cell structure less than Angstroms
The rice cake, said permanent magnet, characterized in that parallel to Zr-containing plate-like phase to the c-plane of the crystal of the intermetallic compound in the microstructure is present. Wherein Oite permanent magnet according to claim 1, cell interior definitive before SL cell structure has and cell boundary portion main ingredient phase of R ₂ Co ₁₇ the phase composed mainly of RCo ₅ wherein A permanent magnet having a microstructure surrounded by two phases of a plate-like phase. 3. The permanent magnet according to claim 1, wherein the content of carbon in the alloy is at most 700 ppm, and the content of oxygen is at most 3000 ppm. 4. A method for producing a permanent magnet according to claim 1.
A is, in weight percent, of 23 to 27% R (R is at least one of rare earth metals including Y) and 3-6% (however, 6 is not included) of Cu and 10% to 25% of Fe and 1.
A method for producing a permanent magnet having an alloy composition consisting of 5 to 4% of Zr and the balance being substantially Co, wherein raw materials are blended so as to have the alloy composition, and at most 1 × A melting step of obtaining a master alloy ingot by melting in a vacuum of 10 ^-2 Torr, a coarse pulverizing step of coarsely pulverizing the obtained mother alloy ingot to obtain a coarsely pulverized powder,
A finely pulverizing step in which the coarsely pulverized powder is finely pulverized in an inert atmosphere to obtain a finely pulverized powder having an average particle size of 1 to 5 μm, and the finely pulverized powder is perpendicular or parallel to the magnetic field in a magnetic field of 7 to 22 KOe. Pressing in a direction with a pressing force of 0.5 to 2.0 ton / cm ² to obtain a compact, and pressing the compact in a vacuum of at most 1 × 10 ⁻² Torr, in an inert atmosphere, A sintering step of sintering at a sintering temperature of 1150 to 1250 ° C. in any one of the atmospheres of these combinations to obtain a sintered body; A solution treatment step of performing heat treatment at a temperature lower by ５０50 ° C., and after the solution treatment step, at least 60 ° C.
Quenching step of quenching at a cooling rate of / min, and after the quenching step, heating and holding at a temperature of 700 to 870 ° C. for at least 1 hour in a vacuum or an inert atmosphere of at most 1 × 10 ⁻² Torr. An aging treatment step of performing aging treatment.