JP2580066B2 - Anisotropic permanent magnet - Google Patents

Description

The present invention relates to an R-Fe (Co) -B anisotropic permanent magnet containing a rare earth element (R), iron (cobalt) and boron as basic components. More specifically, in a low-rare-earth permanent magnet having an R of less than 12 at%, a solidified powder obtained by rapidly cooling an R-Fe (Co) -B-based alloy containing W is plastically deformed and anisotropically formed. The present invention relates to an anisotropic permanent magnet having a product, a high residual magnetic flux density, and good squareness.

<< Conventional Technology >> Conventionally, R-Fe (Co) -B permanent magnets have been developed as rare earth magnets.

Examples of the R-Fe (Co) -B magnet include a sintering method and a quenching method.

The permanent magnet produced by the sintering method is obtained through a complicated process of melting a raw material, casting, coarsely pulverizing an ingot, finely pulverizing, pressing, sintering, and a magnet, so that the manufacturing cost is high.

This sintered magnet is made of R ₂ Fe (Co) with a crystal grain size of about 10 μm.
It is a so-called nucleation magnet in which the crystal of ₁₄ B forms the main phase, and the nucleation of the reverse domain determines the coercive force.

On the other hand, the permanent magnet by the quenching method is obtained through a simple process of dissolving the raw material → high-speed quenching → coarse pulverization → cold pressing (warm pressing) → magnet. It is low.

This quenched magnet is basically the same as the sintered magnet described above.
R ₂ Fe (Co) ₁₄ B compound as main phase, R of about 0.01 to 1 μm
_This is a so-called pinning magnet in which the pinning of the domain wall determines the coercive force by an extremely fine structure in which an amorphous phase surrounds 2Fe (Co) _14B fine particles.

As described above, the coercive force generating mechanism of the quenched magnet is different from the coercive force generating mechanism of the cast magnet as well as the sintered magnet described above.
13% (atomic%, where "%" in this specification means "atomic%"), which is slightly higher than the R content of the main phase (about 11.8%).

When R in the fine particles is less than 12%, the coercive force rapidly deteriorates. JP-A-59-64739 discloses that when R becomes 10%, the coercive force becomes 6 kOe or less.

In order to keep this deterioration of coercive force, R-Fe (C
o) A technique of adding W to a -B quenched magnet has been proposed (see Japanese Patent Application Laid-Open No. 64-703).

<< Problems to be Solved by the Invention >> As described above, R-Fe (C
o) The -B-based quenched magnet can obtain a certain coercive force improving effect by adding W.

By the way, when the R-Fe (Co) -B quenched magnet of a low rare earth element is to be densified or subjected to plastic working, it is necessary to raise the temperature to a considerably high temperature.

For this reason, the high-density anisotropic magnet obtained by plastic working is affected by heat at this high temperature or during the heating process,
Crystal grains of the above R ₂ Fe (Co) ₁₄ B fine particles of about 0.01 to 1 μm grow.

As a result, the pinning effect of the domain wall by the amorphous phase is reduced, and the coercive force of the high-density anisotropic magnet by the plastic working is deteriorated.

However, as the amount of W added increases, the residual magnetic flux density decreases and the squareness also deteriorates, and such a problem cannot be solved by the addition of elements such as Mg and Al.

The present invention has been made in view of the above points, and an object of the present invention is to quench an R-Fe (Co) -B system containing W and having a rare earth element content of less than 12%. An object of the present invention is to propose an anisotropic permanent magnet that can anisotropically magnetize a magnet at a high density by plastic deformation while maintaining a high coercive force, has a high residual magnetic flux density, and has good squareness.

To achieve the "SUMMARY for the" above-mentioned object, an anisotropic permanent magnet according to the present invention, the general formula _{Rx (Fe 1-w Co w} ) 100-xyzuv B y W z T u M
_v (where R is at least one rare earth element including Y,
6 ≦ x ≦ 16, 2 ≦ y ≦ 25, 0 ≦ w ≦ 1.0, z> 0, u>
0, 0 <u + z ≦ 12, 0 <v ≦ 5, T is Nb, Mo, Ti, V, Cr
Wherein M is at least one of Mg, Al, Ga, Sb, Te, Ge, and In), which is a high-density plastically deformed liquid quenched alloy.

 Hereinafter, the anisotropic permanent magnet of the present invention will be described in detail.

As a quenching method for obtaining a liquid quenched alloy having the above general formula, from various methods having various characteristics,
An appropriate method is adopted according to the purpose.

For example, the gun method, piston anvil method, and torsion catapult method can increase the cooling rate.

The centrifugal method, the single-roll method, and the twin-roll method are suitable for industrial production because thin ribbons can be continuously manufactured in large quantities. In these methods, an alloy melted by an electric furnace or a high-frequency furnace is ejected from a nozzle at the tip of a crucible by gas pressure, and is brought into contact with the surface of a cooling rotating body to solidify. For example, in the case of the single roll method, a molten alloy is jetted onto one rotating roll peripheral surface and solidified on the roll peripheral surface.

In addition to these, powder production by a spray method, cavitation method, jetting method in a rotating liquid, spinning method in a water stream, spinning method in a rotating liquid, thin wire manufacturing by a glass-coated spinning method, and the like can also be applied.

The liquid quenched alloy powder, thin ribbon,
A suitable form such as a yarn or a molded body is formed at a temperature of 400 to 1000 ° C., preferably 600 to 850 ° C., at a high density of 70% or more, preferably 90% or more of the theoretical density by HIP (hot isostatic pressing) or hot pressing. Become

After this, 600 ~ 1000 ℃, strain rate 10 ^-4 ~ 1 / sec, processing rate 30
% Or more, preferably 50% or more.

As a result, an anisotropic permanent magnet in which the axes of easy magnetization are aligned in the processing direction can be obtained.

In addition, as the above-mentioned warm plastic working method, any method such as a hot press method and a rolling method can be adopted.

Further, the above strain rate and processing rate are as follows, when the sample thickness after densification is h ₀ , the sample thickness after plastic deformation is h ₁ , and the time required for plastic deformation is t, It shall be expressed as follows.

Next, the reasons for limiting the components of the liquid quenched alloy will be described.

The numerical values of the magnetic properties shown below are values for isotropic powder.

When the amount x of R is less than 6%, the coercive force iHc becomes smaller than 5 kOe, and when it exceeds 16%, the maximum energy product (BH) max becomes 5
MGOe, which is not practically preferable.

When the amount y of B is less than 2%, iHc is small as less than 5 kOe, and when it exceeds 25%, (BH) max is reduced. N as T,
The reason for adding at least one of Mo, Ti, V, and Cr is that all of these elements suppress the decrease in residual magnetic flux density due to the addition of W.

The amount z of W and the amount u of T increase iHc and residual magnetic flux density in very small amounts to improve the squareness.
Both are 0.1% or more, and the effect is remarkable at 0.3% or more. However, when u + z exceeds 12%, (BH) ma
x decreases.

The addition of at least one of Mg, Al, Ga, Sb, Te, Ge and In as M is because all of these elements suppress the growth of crystal grains to suppress the decrease in coercive force and the plastic deformation temperature. It is because it lowers.

The amount v of M is very small and suppresses crystal grain growth and lowers the plastic deformable temperature. However, it is preferably 0.1% or more, and when it exceeds 5%, both (BH) max and iHc decrease.

By replacing Fe with Co, the Curie temperature is improved,
Temperature characteristics are improved. As for the substitution amount w, a magnet having a coercive force of 8 kOe or more can be obtained even when all the Fe is replaced with Co, that is, w = 1 at which a high coercive force can be obtained over the entire area.

The processing conditions at the time of high density and plastic deformation (working) described above are based on the following reasons.

If the temperature at the time of densification is less than 400 ℃, the theoretical density of 7
If it is less than 0%, and if it exceeds 1000 ° C., a decrease in iHc due to crystal grain growth cannot be avoided. In particular, when the temperature is in the range of 600 to 850 ° C., the density becomes 90% or more of the theoretical density, which is more preferable.

If the temperature at the time of plastic deformation is lower than 600 ° C., plastic deformation is impossible in the composition range of the present invention, and if it exceeds 1000 ° C., a decrease in iHc due to crystal grain growth cannot be avoided.

When the strain rate exceeds 1 / sec, uniform plastic deformation is hindered. When the strain rate is lower than 10 ^-4 / sec, a decrease in iHc due to crystal grain growth is inevitable.

The higher the processing rate, the higher the anisotropic ratio,
In order to obtain a residual magnetic flux density Br of 8 kG or more, at least 30
% Or more is required. When the processing rate exceeds 50%
Br of 10 kG or more is obtained, which is more preferable.

<< Operation >> When the molten alloy is quenched and solidified, the structure after quenching generally becomes amorphous or fine crystal grains or a mixed composition thereof, although it differs depending on the alloy composition and quenching conditions.

By subjecting this to a high-density treatment, the structure comprising the microcrystal or amorphous and the microcrystal particles and the size of the microcrystal particles can be further controlled, and the fine crystal particles of about 0.01 to 1 μm are converted into an amorphous phase. A very favorable texture is obtained for the surrounding permanent magnet.

Examining the effects of various additional elements on the R-Fe (Co) -B-based material obtained by the quenching method, it shows a high coercive force even with a composition in which the content of R is less than 12%, especially when W is added, A high-performance magnet suitable for practical use can be manufactured. Also, R
Even when the content is 12% or more, the coercive force is improved by the addition of W.

As described above, although the addition of W contributes to the improvement of the coercive force, the residual magnetic flux density decreases as the content increases, and the squareness deteriorates. With respect to these lowering of residual magnetic flux density and deterioration of squareness, adding an appropriate amount of Nb, Mo, Ti, V, Cr as T is not clear, but the reason is not clear. Deterioration is suppressed. In particular, Mo remarkably expresses this effect. In addition, in the case of a low-earth element R-Fe (Co) -BW four-element quenched magnet, plastic deformation is difficult unless the temperature is about 900 ° C. or more. The coercive force improved by the above addition is drastically reduced.

Mg, Al, Ga, Sb, Te, Ge, M
Addition of an appropriate amount of In lowers the temperature at which plastic deformation is possible, and suppresses crystal grain growth. Therefore, a decrease in coercive force is suppressed. In particular, Al and Ga exhibit this effect remarkably.

<< Examples >> Alloys having the compositions shown in Table 1 were produced by arc melting.

This alloy was ejected by applying a gas pressure of argon through a quartz nozzle to the surface of a roll rotating at 20 m / sec by using a liquid quenching method, and was cooled at a high speed to obtain an amorphous or microcrystalline ribbon.

The ribbon was crushed to 60 mesh or less, and was formed using a hot press at a temperature of 700 ° C. and a pressure of ² ton / cm ² .

The molded body was hot-pressed again in a state where the side surface was free and was subjected to warm plastic deformation. At this time, the strain rate is 10 ^-3
/ sec, temperature was 700 ° C.

 Table 1 shows the magnet properties after plastic working together with the composition.

From Table 1, for the R-Fe (Co) -BWM system, T
(Nb, Mo, etc.) and W are combined to improve coercive force, increase the maximum energy product, increase the residual magnetic flux density, and improve the squareness as compared with the case of adding W alone. It turns out that it becomes.

<< Effect of the Invention >> As described in detail above, according to the present invention, R-Fe (Co)-
Since the composition is such that an appropriate amount of M such as Al or Ga and T such as Nb or Mo is added to the B-based composition in an appropriate amount, even in a region where the content of the rare earth element R is small (less than 12%), the content of the rare earth element is large. Higher coercive force iHc comparable to that obtained and cost reduction can be achieved. Particularly, compared to the case of adding W alone, the amount of added elements can be reduced to achieve the same coercive force. And deterioration of squareness can be suppressed.

Then, in the present invention, after the density is increased, the material is anisotropic due to plastic deformation, so that the maximum energy product (BH) max is improved. In addition, since M (Al, Ga, etc.) is included in the material composition, warm plastic working can be performed at a relatively low temperature, the main phase does not become coarse, and a decrease in coercive force can be prevented.

Thus, according to the present invention, an anisotropic permanent magnet having practically excellent characteristics can be obtained.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Kazuo Matsui 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (56) References JP-A-62-202506 (JP, A) 1963-213316 (JP, A)

Claims (1)

(57) [Claims] 1. A general formula _{R x (Fe 1-w Co} w) 100-xyzuv B y W
_z T _u M _v (where R is at least one kind of rare earth element including Y, 6 ≦ x ≦ 16, 2 ≦ y ≦ 25, 0 ≦ w ≦ 1.0, z>
0, u> 0, 0 <u + z ≦ 12, 0 <v ≦ 5, T is Nb, M
o, at least one of Ti, V, Cr, M is Mg, Al, Ga, S
An anisotropic permanent magnet comprising a high-density plastically deformed liquid quenched alloy of at least one of b, Te, Ge, and In).