JP2001207202A - Method for producing metallic bulk material having high coercive force and metallic bulk material and target material produced thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method, e.g. capable of producing a target material usable for production of a magnetic thin film having high soft magnetic properties by magnetron sputtering or the like as a metallic bulk material having high coercive force. SOLUTION: As raw material powder those coercive force is made high from a composition having high soft magnetic properties in essence, the raw material powder is subjected to impact compression and is bulked as having the same magnetic properties to obtain a metallic bulk material having high coercive force. It is preferable that the raw material powder is subjected to mechanical alloying treatment before the impact compression, and the raw material is refined and is made into solid solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal bulk material having a high coercive force and a metal bulk material produced thereby, and more particularly to a magnetron sputtering method which usually has a composition having high soft magnetic properties. The present invention relates to a method for producing a metal bulk material having a high coercive force suitable for a target material and the like and a metal bulk material obtained by the method.

[0002]

2. Description of the Related Art Thin films having high soft magnetic properties are used for thin-film magnetic disks and magnetic heads. Such a magnetic thin film is produced by sputtering using an alloy target having substantially the same composition as the thin film. 2. Description of the Related Art Sputtering efficiency is increased by applying a magnetic field at the time of sputtering, and directionality is imparted to a thin film. If the magnetic properties of the target are large during magnetic field sputtering, that is, magnetron sputtering, the magnetic field distribution around the target, particularly near the target surface, will bend. Therefore, the plasma beam at the time of magnetron sputtering may be disturbed near the target, and the characteristics of the target magnetic thin film may be reduced, or the sputtering efficiency may be reduced.

Therefore, when a thin film having high magnetic properties is obtained by sputtering, the target is required to have low magnetic properties, in other words, to have a relatively high coercive force.

The inventor of the present invention obtained a non-equilibrium solid solution powder by applying mechanical alloying to a metal composition system, for example, an iron-copper system and an iron-tungsten system, which are difficult to alloy by a normal melting method. We invented obtaining a non-equilibrium solid solution bulk material by subjecting non-equilibrium solid solution powder to impact compression, and filed a patent application as Japanese Patent Application No. 9-201081 (filed on July 28, 1997). However, there is no mention of how the magnetic properties are changed by the mechanical alloying treatment or the impact compression.

[0005]

According to the present invention, a metal bulk material having a high coercive force can be obtained while having a composition of a metal or alloy (for example, an iron-cobalt alloy) which originally exhibits high soft magnetic characteristics. It is intended to provide a way.

It is another object of the present invention to provide a metal bulk material having a high coercive force while having a metal or alloy composition (eg, an iron-cobalt alloy) that originally exhibits high soft magnetic characteristics.

Further, the present invention provides a manufacturing method capable of obtaining a metal bulk target material having a high coercive force while having a composition of a metal or an alloy which originally exhibits high soft magnetic characteristics, and a target material thereof. Is also aimed at.

The term “high coercive force” used in this specification
The term means that the material has a value that is lower than the soft magnetic properties inherent to the material, that is, a value lower than the permeability or saturation magnetic flux density, and that the material has a value that is relatively larger than the intrinsic coercive force. ing.

[0009]

The inventor of the present invention has reached the present invention by studying the application of the above-described shock compression to an alloy powder having a composition originally exhibiting high soft magnetic properties.

Therefore, the method for producing a metal bulk material having a high coercive force according to the present invention is to compress a metal or alloy powder having a high coercive force, which is originally a composition having a high soft magnetic property, into a bulk material by impact compression. It is characterized by the following.

[0011] The above-mentioned manufacturing method is characterized in that an Fe-based alloy, particularly Fe-
It is suitable for a Co alloy.

Further, the metal bulk material having a high coercive force of the present invention is a bulk material obtained by subjecting a metal or alloy powder having a high coercive force to shock compression while having a composition originally having high soft magnetic properties. Features.

The bulk material is an Fe-based alloy, especially Fe-C
An o-alloy is preferred.

The target material of the present invention is characterized by being composed of a bulk metal material having a high coercive force obtained by subjecting a metal or alloy powder having a high coercive force to shock compression while having a composition originally having a high soft magnetic property. And The bulk material is preferably an Fe-based alloy, particularly an Fe-Co alloy.

In the present invention, shock compression is used to produce a bulk material. In shock compression, an ultra-high pressure state is realized by applying a high stress far exceeding the elastic limit of a material in an extremely short time of about nanoseconds or microseconds. In particular, compression by a plane shock wave is uniaxial compression. In addition, according to the impact compression, it is possible to solidify or bulk while maintaining the non-equilibrium state, so that ultrafine particles (nanocrystals, submicron particles or fine particles) of a metal or its alloy are solidified as they are. It becomes a bulk body having a fine structure.

In the method for producing a metal bulk material having a high coercive force according to the present invention, a metal powder constituting the target alloy or its alloy powder can be used as a starting material. The use of metal powder is more preferred because of lower soft magnetic properties. Here, the metal or alloy powder can be obtained by an atomizing method, a mechanical alloying treatment, or a combination thereof, and a material subjected to a mechanical alloying treatment is particularly preferable. By subjecting the raw material powder to mechanical alloying treatment, the structure of the metal or alloy mainly contained in the raw material powder mainly appears. Due to this mechanical alloying, a non-equilibrium solid solution powder is formed, and as described later, the soft magnetic properties are reduced and the coercive force is increased. The mechanical alloying processing time can be adjusted so that the coercive force becomes a value suitable for the application. A metal or alloy powder having reduced soft magnetic properties and increased coercive force can be subjected to impact compression to obtain a bulk body with the same properties.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION For Fe—Co system, a commercially available metal powder is mixed and subjected to mechanical alloying.
Alternatively, a powder was obtained from an Fe—Co melt by an atomizing method, or the atomized powder was further subjected to mechanical alloying to produce a powder, and a metal bulk material was produced from the powder by impact compression. It is known that Fe-Co alloys form solid solutions in almost all ranges of their composition ratios in molten products and exhibit high soft magnetic properties. Therefore, the following experiment was conducted so that the molar ratio of Fe and Co was about 70:30. Table 1
Atomized powders of Fe powder, Co powder and Fe-30 mol% Co alloy shown in Table 1 were used. Here, in the atomization method, a melt of Fe-30 mol% Co was obtained by high frequency melting or the like, and the melt at about 1600 ° C. was injected into flowing water, argon, and a nitrogen jet stream to make powder.

[0018]

[Table 1]

In the experiment conducted here, a non-equilibrium solid solution powder was obtained by subjecting a mixture of Fe powder and Co powder to a composition ratio (mol%) of about 70:30 by mechanical alloying. The resultant was subjected to impact compression to obtain a metal bulk material (corresponding to (1) to (4) in Table 2). In parallel with this, the atomized powder of the Fe-30 mol% Co alloy in Table 1 was subjected to impact compression to obtain a metal bulk material (corresponding to (5) in Table 2). Further, the metal alloy was mechanically alloyed after the atomizing treatment and subjected to impact compression to obtain a metal bulk material (corresponding to (6) to (8) in Table 2). As a comparative product, a Fe-29.5 mol% Co alloy was produced by a conventional melting method (corresponding to (0) in Table 2).

Here, the impact compression was applied to the powder using a single-stage keyed gun. At that time, the sample was sealed in a metal capsule made of brass and subjected to impact compression at a collision speed of 1.400 Km / s or more using a 2024 aluminum alloy, copper, or tungsten plate as the collision plate. In addition, the mechanical alloying treatment was performed using a planetary ball mill (container 45 ml, processing amount 20 g /
Using a batch, container material S ₃ N ₄ , and ball material ZrO ₂ ), the number of revolutions was set to about 2,000 rpm, and the atmosphere in the ball mill container was Ar, for 10 minutes, 1 hour, and 21 hours, respectively.

Table 2 shows the magnetic properties of the thus obtained metal bulk material. In this table, MA1
0 min indicates that the mechanical alloying process was performed for 10 minutes, and V = 1.471 Km / s and the like indicate the collision speed during impact compression. μm, Hc (Oe), B
(G) at25Oe is the maximum magnetic permeability, coercive force,
e shows the saturation magnetic flux density.

[0022]

[Table 2]

As is clear from this table, the Fe--Co alloy obtained by the conventional melting method has a small coercive force of 4.3 Oe, a maximum magnetic permeability of 840 and a saturation magnetic flux density of 1230.
It showed a large soft magnetic property of 0 G. Each of the metal bulk materials subjected to the impact compression treatment had a large coercive force and a low maximum magnetic permeability μm and a low saturation magnetic flux density B. In particular, those subjected to mechanical alloying for 21 hours and then subjected to impact compression have a maximum magnetic permeability μm of 80, which is 1/1 of the molten product.
0 or less. In particular, the coercive force H of (1) to (4) in Table 2
Looking at (c), they are all larger than the molten product (0), but the mechanical alloying time also increases up to 1 hour, and tends to decrease when the mechanical alloying time is longer than that. I understand.

Each of the atomized powders subjected to impact compression ((5) to (8)) has a larger coercive force Hc, a smaller maximum magnetic permeability μm and a smaller saturation magnetic flux density B than the melted product. Has become. Among them, the one with mechanical alloying added for one hour tends to have a large coercive force,
After 21 hours, the coercive force tends to decrease slightly.

FIGS. 1 and 2 show X-ray diffraction patterns of the metal bulk material under the manufacturing conditions shown in Table 2. FIG.
The mixture of powder and Co powder is subjected to mechanical alloying and then subjected to impact compression to form a bulk material. The upper part of the figure shows the mixture of Fe powder and Co powder used as starting materials and the melted product. Is shown. FIG. 2
Is a mechanical bulking of atomized powder followed by shock compression to form a metal bulk material. Also shown.

From these X-ray diffraction patterns, it can be seen that by performing mechanical alloying treatment, the peak of Co almost disappeared, and the solid solution was formed. It is surprising that the coercive force is increased and the maximum magnetic permeability and the saturation magnetic flux density are reduced as shown in Table 2 despite the solid solution. Further, it can be seen that the half-width of the diffraction line is increased by performing the mechanical alloying treatment for a long time.

FIGS. 3 to 10 show surface micrographs of the metal bulk material obtained above. The photograph (a) at the top of each figure is the one before corrosion and has a scale of 50 μm / 17 mm, and indentations of Vickers hardness appear. The middle photo (b) is a corroded one with a scale of 50 μm / 17 mm,
The lower photograph (c) is a corroded one with a scale of 10μ.
m / 17 mm. It has a single-phase polycrystalline structure of about 100
It can be seen that the crystal grains are μm. A mechanical structure is applied to the powder to give a finer structure, and a long-time mechanical alloying process promotes finer and more solid-solution alloying, resulting in a single-phase fine structure. I understand. It can be seen that the solid solution of any of FIGS. 4 to 10 has progressed and has become a bulk material.

Also, the crystal structure of the metal bulk material obtained above,
The hardness and particle size were determined and are shown in Table 3. What is shown in parentheses in the column of the crystal structure is a little as an X-ray diffraction pattern, and it can be said that almost all but bcc have disappeared due to mechanical alloying. Although the hardness is increased by the impact compression, it is considered that the tissue contains much strain.

[0029]

[Table 3]

The above phenomenon can be considered as follows.

In an Fe—Co alloy, the magnetic properties are determined by the energy contribution of the magnetic anisotropy up to the crystal grain size of about 30 nm, and the magnetization process mainly depends on the crystal anisotropy and the direction of the magnetic arrangement parallel to the axis of easy magnetization. Dominated by The coercive force of the obtained bulk body is increased by magnetic domain pinning at crystal grain boundaries.

At about 30 nm or less, the exchange interaction becomes dominant and hinders the magnetic moment from the orientation parallel to the easy axis of magnetization. As a result, randomly oriented crystal grains interact by exchange interaction. By averaging some crystal grains, the effective anisotropy decreases, and the coercive force decreases.

Therefore, as can be seen from the photograph, the mechanical alloying time is about 1 hour, but the crystal grain boundaries are striped, but the crystal grain size decreases, and the coercive force increases as compared with that obtained by the melting method. . However, over 5 hours, alloying and miniaturization proceed, and the particle size becomes broader in the X-ray pattern,
The crystal grain size obtained by using Scherrer's formula is on the order of several tens of nanometers, and the coercive force decreases. In the photograph, the grain boundaries of the striped pattern disappear, and after 21 hours, the structure is such that relatively large secondary particles composed of ultrafine particles can be seen.

When the alloy powder obtained by the atomizing method is subjected to mechanical alloying, the crystal grain size of the starting material is smaller than that obtained by the melting method.
As in the case of mechanical alloying of e and Co powders, the crystal grain boundaries are striped as shown in the photograph until the mechanical alloying time is about 1 hour, but the crystal grain size decreases and the coercive force increases. To go. However, in 5 hours or more, miniaturization progresses, and the particle size becomes broad in the X-ray pattern,
The crystal grain size obtained by using Scherrer's formula is on the order of several tens of nanometers, and the coercive force is conversely reduced. In the photograph, the grain boundaries of the striped pattern disappear, and at 21 hours, relatively large round secondary particles composed of ultrafine particles can be seen.

Although only the Fe-Co alloy has been described in the above description, the present invention can be applied to other alloys and ternary, quaternary and other multi-element alloys which originally exhibit high magnetic properties. .

[0036]

As described above in detail, according to the present invention, it is possible to obtain a metal bulk material having a high coercive force from a metal or alloy powder having a high coercive force while having a composition having an originally high soft magnetic property. did it.

The metal bulk material manufactured according to the present invention can be used as a target material for magnetron sputtering.

[Brief description of the drawings]

FIG. 1 is a diagram showing X-ray diffraction patterns of a mixture of Fe powder and Co powder, a molten product, and a metal bulk material produced by impact compression according to the present invention, together with mechanical alloying (MA) time.

FIG. 2 is a diagram showing an X-ray diffraction pattern of a Fe—Co alloy atomized powder and a metal bulk material produced by impact compression by treating the atomized powder with changing mechanical alloying (MA) time.

FIG. 3 is a metallographic micrograph of a molten product of an Fe—Co alloy, in which (a) shows a scale of 50 μm / 17 mm before corrosion.
(B) scale 50 μm / 17 mm after corrosion,
(C) is a diagram showing a scale of 10 μm / 17 mm after corrosion.

FIG. 4 is a metal microstructure photograph of a metal bulk material obtained by subjecting a mixed powder of Fe and Co to mechanical alloying according to the present invention for 10 minutes and then performing impact compression, and (a) shows a scale of 50 μm / corrosion before corrosion. 17B is a diagram showing a scale of 50 μm / 17 mm after corrosion, and FIG. 13C is a diagram showing a scale of 10 μm / 17 mm after corrosion.

FIG. 5 is a metallographic micrograph of a metal bulk material obtained by subjecting a mixed powder of Fe and Co to shock compression after one hour of mechanical alloying according to the present invention, wherein (a) shows a scale of 50 μm / 17B is a diagram showing a scale of 50 μm / 17 mm after corrosion, and FIG. 13C is a diagram showing a scale of 10 μm / 17 mm after corrosion.

FIG. 6 is a micrograph of a metal microstructure of a bulk metal material obtained by subjecting a mixed powder of Fe and Co to impact compression after 21 hours of mechanical alloying in accordance with the present invention, and (a) shows a scale of 50 μm / 17B is a diagram showing a scale of 50 μm / 17 mm after corrosion, and FIG. 13C is a diagram showing a scale of 10 μm / 17 mm after corrosion.

FIG. 7 is a metal microstructure photograph of a metal bulk material produced by subjecting Fe—Co alloy atomized powder to impact compression without mechanical alloying according to the present invention, and (a).
FIG. 3B is a diagram showing a scale of 50 μm / 17 mm before corrosion, FIG. 4B is a diagram showing a scale of 50 μm / 17 mm after corrosion, and FIG.

FIG. 8 is a metal microstructure photograph of a metal bulk material produced by subjecting a Fe—Co alloy atomized powder to mechanical alloying according to the present invention for 10 minutes and then performing impact compression.
(A) shows a scale of 50 μm / 17 mm before corrosion,
(B) shows a scale of 50 μm / 17 mm after corrosion,
(C) is a diagram showing a scale of 10 μm / 17 mm after corrosion.

FIG. 9 is a metallographic micrograph of a metal bulk material produced by subjecting one hour after mechanical alloying from Fe—Co alloy atomized powder to mechanical alloying according to the present invention and then performing impact compression;
(A) shows a scale of 50 μm / 17 mm before corrosion,
(B) shows a scale of 50 μm / 17 mm after corrosion,
(C) is a diagram showing a scale of 10 μm / 17 mm after corrosion.

FIG. 10 is a metal microstructure photograph of a metal bulk material produced by subjecting Fe—Co alloy atomized powder to impact compression after 21 hours of mechanical alloying according to the present invention,
(A) shows a scale of 50 μm / 17 mm before corrosion,
(B) shows a scale of 50 μm / 17 mm after corrosion,
(C) is a diagram showing a scale of 10 μm / 17 mm after corrosion.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B22F 9/08 B22F 9/08 M C22C 33/02 C22C 33/02 G C23C 14/34 C23C 14/34 A (72) Inventor Hideo Murata 2107-2 Yasugi-cho, Yasugi City, Shimane Pref. Hitachi Metals Research Institute, Metallurgy Research Institute (72) Inventor Masahiko Sakakibara 1-1-2 Shibaura, Minato-ku, Tokyo F-term (reference) 4K017 AA03 AA04 BA06 BB06 DA02 DA09 EB00 EK01 4K018 AA10 AA25 BC16 CA01 CA41 KA29 KA45 4K029 CA05 DC04 DC07 DC39

Claims (12)

[Claims] 1. A method for producing a metal bulk material having a high coercive force, comprising shock-compressing a metal or alloy powder originally having a composition having a high soft magnetic property into a bulk material. 2. The method for producing a metal bulk material having a high coercive force according to claim 1, wherein the metal or alloy powder is obtained by an atomizing method, a mechanical alloying treatment, or a combination thereof. 3. The method for producing a metal bulk material having a high coercive force according to claim 1, wherein the bulk material is an Fe-based alloy. 4. The method for producing a metal bulk material having a high coercive force according to claim 1, wherein the bulk material is an Fe—Co alloy. 5. A metal bulk material having a high coercive force, which is obtained by subjecting a metal or alloy powder originally having a composition having a high soft magnetic property to shock compression. 6. The metal bulk material having a high coercive force according to claim 5, wherein said metal or alloy powder is obtained by an atomizing method, a mechanical alloying treatment, or a combination thereof. 7. The metal bulk material having a high coercive force according to claim 5, wherein the bulk material is an Fe-based alloy. 8. The bulk metal having a high coercive force according to claim 5, wherein the bulk material is an Fe—Co alloy. 9. A target material comprising a metal bulk material having a high coercive force obtained by subjecting a metal or alloy powder originally having a composition having a high soft magnetic property to impact compression. 10. The target material according to claim 9, wherein the metal or alloy powder is obtained by an atomizing method, a mechanical alloying treatment, or a combination thereof. 11. The target material according to claim 9, wherein the bulk material is an Fe-based alloy. 12. The target material according to claim 9, wherein the bulk material is an Fe—Co alloy.