JPH0623415B2 - Method for producing amorphous alloy compact - Google Patents

Description

Detailed Description of the Invention a. TECHNICAL FIELD The present invention relates to a method for producing an amorphous alloy compact.

B. 2. Description of the Related Art Conventionally, Ni is used as a soft magnetic material having good magnetic characteristics in the high frequency region of over 100 KHz, especially about 0.5 to 10 MHz.
-Zn-based or Mn-Zn-based oxide (ferrite) -based materials are available. In particular, Mn-Zn-based ferrite is 5M.
The effective magnetic permeability at Hz is about 600, which shows excellent magnetic characteristics.

However, with the progress of high-density magnetic recording technology, in place of a conventional magnetic tape using an oxide magnetic powder such as γ-Fe ₂ O ₃ or CrO ₂ as a magnetic recording medium, a fine iron powder or a Co-based magnetic tape is used. A so-called metal tape that is used as a magnetic recording medium by coating or vapor depositing a magnetic alloy has come to be used. In the future, this type of metal tape will be 8 mm VT.
It is in the mainstream of magnetic tapes such as R.

By the way, the magnetic characteristics of the magnetic recording medium used for this type of metal tape are as follows: γ-Fe ₂ O ₃ and CrO ₂
The magnetic flux density (Bs) and the coercive force (Hc) are remarkably large as compared with the magnetic characteristics of the magnetic recording medium made of an oxide magnetic material such as.

Therefore, in the case of a metal tape, a magnetic head using a magnetic material having a high saturation magnetic flux density cannot sufficiently store or read data. Therefore, an oxide magnetic material such as Mn—Zn ferrite is used as an iron core. No magnetic head can be used.

Therefore, as a magnetic iron core material for a magnetic head used for a metal tape, a magnetic material iron core material having a large saturation magnetic flux density and good frequency characteristics in a high frequency region is used instead of an oxide magnetic material. , Sendust and amorphous magnetic alloys have been proposed.

Sendust and amorphous magnetic alloys are known as high-permeability alloys and have good magnetic characteristics in the high frequency range as compared with other metal-based magnetic materials such as Permalloy, and also have a magnetic flux density of oxide-based magnetic materials. However, it is a promising material as an iron core material for magnetic heads, etc., however. These conventionally proposed magnetic materials also have some drawbacks and have not yet satisfied the required characteristics, and further improvements are desired.

That is, sendust has an initial permeability μo of about 30,000, which exhibits magnetic characteristics at direct current, and has good direct current characteristics, but has an effective permeability that exhibits magnetic characteristics in the frequency region as the frequency increases in the high frequency region. The value of magnetic permeability (μeff) sharply decreases, and, for example, the effective magnetic permeability in the frequency range (5 MHz) used in 8 mm VTR decreases to about 60 (when the plate thickness is 0.1 mm). The decrease in the effective magnetic permeability in this frequency range is due to the large eddy current loss because the electric resistivity of Sendust is about 80 μΩ-cm, which is dependent on that of the oxide magnetic material. By processing Sendust into a thin plate and using it, it is possible to prevent the decrease of the effective magnetic permeability μeff to some extent.

However, sendust has a low electrical resistivity, so
To obtain an effective magnetic permeability of μeff = 500 or more in the high frequency region of 5 MHz, it is necessary to make sendust an extremely thin plate material of approximately 10 μm or less, but it is industrially necessary to make it an extremely thin plate material by machining. Impossible.

Amorphous magnetic alloys are also known as magnetic materials exhibiting high magnetic permeability, and particularly, magnetostriction λ = 1 is close to, for example, Co—Fe—Si.
This type of B-type amorphous magnetic alloy has been conventionally used as a material for a magnetic head for audio or for a VTR using a general magnetic tape (using an oxide magnetic recording medium). Further, the amorphous magnetic alloy has a larger electric resistivity than that of Sendust, and therefore, the effective permeability μeff is less likely to decrease due to eddy current loss, and the effective permeability in a high frequency region is superior to that of Sendust.

Therefore, the amorphous magnetic alloy is extremely suitable as a material for a high frequency transformer or an iron core of a magnetic head. Further, the amorphous alloy is remarkably tougher and has a higher hardness than a crystalline alloy having the same chemical composition, and is therefore particularly suitable as a material for the iron core of the magnetic head.

By the way, amorphous alloys are manufactured by supplying molten alloy onto a rapidly rotating roll by a single roll method, a twin roll method, a triple roll method, etc. and rapidly solidifying it, and supplying it in the state of a thin ribbon. However, when a thin iron ribbon of this type is used to form a magnetic iron core, there is a problem to be solved in processing and it is difficult to industrially adopt it.

That is, in order to process a desired magnetic head from an amorphous alloy thin ribbon material manufactured by the liquid quenching method, the outer shape and the winding insertion groove are previously etched one by one according to the shape and size of the iron core. It is cut out by laser processing or processed by a method such as punching with a press die, but the former two are not suitable as industrial methods with poor productivity, and the latter is the hardness of amorphous alloy. Is extremely high (about HV = 900), which is not an economical method because the die consumption is extremely heavy.
In addition, the thin ribbon material produced by the liquid quenching method directly melts the molten metal to directly form the thin ribbon material, so that the dimensional accuracy as the thin sheet material is poor and the thin ribbon material is previously obtained in order to obtain good magnetic characteristics. There are many difficulties in processing, such as the fact that it has to be processed to a certain thickness by polishing.
Further, as a manufacturing technology problem when manufacturing a thin ribbon material by the liquid quenching method, there is a problem that it is difficult to avoid the occurrence of surface defects due to inclusion of bubbles or inclusions such as oxides during manufacturing. Therefore, defects are likely to occur in the product (iron core) and the production hold is low.

C. OBJECT OF THE INVENTION The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a method for producing an amorphous alloy compact, which solves the problems of conventional products made of amorphous alloy ribbons.

D. Structure of the Invention The present invention comprises a step of producing an amorphous alloy powder and a step of molding only the amorphous alloy powder at a temperature in a range above its glass transition temperature and below its crystallization temperature. The present invention relates to a method for producing a crystalline alloy compact.

Since the amorphous alloy is excellent in toughness as described above and has a high hardness, it is extremely difficult to grind the ribbon material into powder. As a method for producing the amorphous alloy powder,
Has a surface layer with low wettability for molten metal, 2m /
The molten metal is supplied to the surface of the roll rotating at a peripheral speed of sec or more through a nozzle, and the molten metal is divided into fine molten metal droplets.
It is preferable to collide with a metallic rotating body rotating at a peripheral speed of 10 m / sec or more to rapidly solidify the metallic rotating body.

The vitrification transition temperature is a temperature at which a solid state transitions from a solid state to a liquid state due to an amorphous structure, and has the same definition as a term used in the fields of glass and polymers.

If the molding temperature is below the glassification transition temperature, it is difficult to mold, and above the crystallization temperature, an amorphous → crystalline transformation occurs, and since this transformation is irreversible, the amorphous alloy Excellent properties are lost.

The temperature range between the vitrification transition temperature and the crystallization temperature is generally not large. For example, a Co ₇₅ Si ₁₅ B ₁₀ alloy (the number attached to the element symbol represents the atomic% of the element component).
The same applies hereinafter. ), The above temperature range is about 10 ° C. As a result of repeated studies, the present inventors have found that the above temperature range varies depending on the chemical composition of the alloy, and there is a composition range in which the above temperature range is significantly widened.

In the present invention, the amorphous alloy powder is molded at a temperature within the above temperature range. However, if the temperature range is less than 30 K, it is not easy to keep the processing temperature within this temperature range. Absent. It is particularly preferable to form an amorphous alloy powder having the above temperature range of 50K or higher. Also, the molding temperature is
More preferably, the temperature is higher than the vitrification transition temperature by 20 K and lower than the crystallization temperature.

E. Example First, a preliminary experiment for investigating how the vitrification transition temperature, the crystallization temperature, and the easiness of deformation change with temperature using an amorphous alloy ribbon will be described.

Preliminary Experiment 1 An amorphous alloy ribbon having a chemical composition of Co ₇₅ Si ₁₀ B ₁₅ was prepared by the single roll method. The thickness of this ribbon is 20μ
m, width is 1 mm. A tensile stress of 0.6 kg / mm ² was applied to this ribbon, and the dimensional change at a gauge length of 10 mm was measured while heating from that temperature at a heating rate of 5 ° C./min from room temperature.

The measurement results are as shown in FIG.

Dimensional change Δl, changes linearly up to a temperature slightly lower than Tg, and increases sharply at temperatures above Tg.
A clear bending point A is observed at the temperature indicated by Tx. Tg is a vitrification transition temperature and Tx is a crystallization temperature.

From room temperature to a temperature slightly lower than Tg, change in dimensional change due to temperature change α ₁ Is constant. Between Tg and Tx, the change in dimensional change due to temperature change α ₂ Is significantly larger than α ₁ . Below, α ₁ is 1
The secondary dimensional change rate, α ₂ is called the secondary dimensional change rate.

The glass transition temperature (Tg) of this amorphous alloy is 440 ° C,
The crystallization temperature (Tx) is 500 ° C.

From the above results, within the temperature range between Tg and Tx,
Under the same stress, the deformation becomes higher than the temperature below Tg,
It will be understood that when the powder is molded, the powder particles are easily deformed and the springback is extremely small, so that the powder is easily molded.

In the curve of FIG. 1, an inflection point is observed at a point B slightly exceeding the temperature 460 ° C. which is 20 ° C. higher than the glass transition temperature Tg, and Δl sharply increases at a temperature above the point B. Therefore, it can be understood that the molding temperature is more preferably within the range of the point B or higher and the crystallization temperature lower than the point A.

Preliminary Experiment 2 An amorphous alloy ribbon having a chemical composition of Co _{90 -X} Si ₁₀ Bx and varying x was prepared by a single roll method. The thickness of these ribbons is 20-25 μm.

These ribbons were tested in the same manner as in Preliminary Experiment 1 to measure the vitrification transition temperature (Tg), crystallization temperature (Tx) and secondary dimensional change rate (α ₂ ).

The test results are shown in FIG.

Temperature range between the vitrification transition temperature and the crystallization temperature (Tx
-Tg) has a maximum value when x is around 15 atom% (Co ₇₅ Si ₁₀ B ₁₅ ), and the value is extremely large at 16K. α ₂ increases as x increases, and x 15 atomic% (Co ₇₅ Si ₁₀
B ₁₅ ) is about 100 × 10 ⁻⁶ / K, which is an order of magnitude larger than α ₁ ((10 to 13) × 10 ⁻⁶ / K) of this amorphous alloy.

Preliminary Experiment 3 An amorphous alloy ribbon having a chemical composition of Co ₇₅ Si _25-X Bx and varying x was prepared by a single roll method. The thickness of these ribbons is 20-25 μm.

These ribbons were tested in the same manner as in Preliminary Experiment 2.

The test results are shown in FIG.

Tx-Tg shows a maximum value at x15 atomic%, and as in the case of the above-mentioned preliminary experiment 2, Co ₇₅ Si ₁₀ B ₁₅ has the largest T.
x-Tg is shown. In this experiment, α ₂ also shows a maximum value near x15 atom%. From the above results, Co ₇₅ Si
_It can be seen that the amorphous alloy of ₁₀ B ₁₅ has extremely excellent formability in the temperature range of Tx-Tg.

Preliminary Experiment 4 An amorphous alloy in which a part of Co in the amorphous alloy of Co ₇₅ Si ₁₀ B ₁₅ was replaced with Fe was produced, and the same tests as those in the Preliminary Experiments 2 and 3 were conducted.

The test results are shown in FIG.

No apparent change in Tx-Tg due to x was observed. Both Tg and Tx slightly increase until x is 10 atomic%. Also, when x is up to 10 atom%, α ₂ obviously increases, and 10 atom%
Above, the rise is insignificant. Therefore, substituting a part of Co with Fe is advantageous from the viewpoint of improving formability.

Hereinafter, specific examples of the present invention will be described.

Example 1 Co ₇₅ Si showing good results in the preliminary experiments 2 and 3
₁₀ B ₁₅ amorphous alloy ribbon, part of Co of this alloy is F
An amorphous alloy ribbon of Co ₇₀ Fe ₅ Si ₁₀ B ₁₅ substituted with e, an amorphous alloy ribbon of Co _70.3 Fe _4.7 Si ₁₅ B ₁₀ and Co _68.8 Fe _4.2 Si ₁₅ B ₁₂ which are zero magnetostrictive materials, and a high magnetic flux Density materials Co ₇₅ Fe ₅ Si ₄ B ₁₆ and Ni
_An amorphous alloy ribbon of ₇₅ Si ₈ B ₁₇ was produced by the single roll method. The thickness of these ribbons is 20 μm.

These ribbons were tested in the same manner as in the preliminary experiments 2, 3 and 4.

The test results are shown in Table 1 below.

Amorphous alloy powder was produced by the following method from a molten metal having the same chemical composition as those of the amorphous alloy ribbons.

FIG. 5 shows an outline of the production used for producing the amorphous alloy powder, in which the molten metal 2 having the above chemical composition contained in the crucible 1 is passed through a quartz tube nozzle 3 cooled by a water cooling jacket 5. Then, it was dropped and supplied toward the gap between the graphite rolls 4a and 4b. The rolls 4a and 4b have a diameter of 60 mm and are opposed to each other with a gap of 0.05 mm, and each is 500 rpm (peripheral speed 15.7 m / sec).
I rotated it at. The molten metal passing between the rolls 4a and 4b of the roll pair 4 has a negative pressure to generate cavitation, and becomes fine molten metal droplets 6 which are discharged downward at a high speed, and the surface of the copper rotating cylindrical body 7 ( It collides with a peripheral velocity of 52.4 m / sec) and rapidly solidifies to form an amorphous alloy powder 8 having an average particle size of 74 to 149 μm, which is collected in a container 9.

The amorphous alloy powder manufactured as described above was filled into a maraging steel mold, heated to the molding temperature shown in Table 1 for about 50 minutes, and kept at that temperature for 15 minutes 100 kg / mm. ²
It was compression-molded with a molding pressure of 5 mm to obtain a molded body having a diameter of 5 mm and a height of 5 mm.

The density and Vickers hardness of these molded products were measured.

All the densities exceeded 90%, and the hardness was high as also shown in Table 1, and it is understood that all the obtained molded articles are extremely dense.

Example 2 Co _68,8 Fe _4.2 Si ₁₅ B ₁₂ amorphous alloy powder was molded under the same conditions as in Example 1 above. The powder magnetic core thus obtained had a high magnetic permeability of 300 at 1 MHz. Conventional powder magnetic core has a low density of 60-70%, so 10
Only a magnetic permeability of about 0 is obtained.

Example 3 The amorphous alloy powder used in Example 1 was molded at different molding temperatures, and the hardness was measured. The other conditions are the same as in the first embodiment.

The measurement results are as shown in Table 2 below.

From the above results, when the forming temperature is set to a temperature higher than Tg and lower than Tx, the amorphous alloy is tough and has high hardness. It can be understood that the molding can be easily carried out, and if the molding temperature is higher than Tg + 20K and lower than Tx, the molding becomes easier and a denser amorphous alloy compact can be obtained. For that purpose, it is desirable that the temperature range between Tg and Tx is as wide as possible, and this temperature range is
It is preferable to form a powder of an amorphous alloy of 40K or higher, more preferably 50K or higher.

As described above, the method of the present invention is easy to mold, and since only the amorphous alloy powder is molded, the desired shape,
An amorphous alloy compact having a size can be obtained, and there is almost no waste of material, and the compact can be produced with a high yield.

F. EFFECTS OF THE INVENTION As described above, according to the method for producing an amorphous alloy compact according to the present invention, the following effects can be obtained.

(i) Since the amorphous alloy powder is manufactured and only this powder is molded, there is almost no waste of material, and the amorphous alloy molded body can be manufactured with high yield.

(ii) In order to mold at a temperature exceeding the vitrification transition temperature,
The secondary dimensional change rate (α ₂ ) has a large value, and as a result, the springback is extremely small and the molding is easy.

(iii) Since it is formed at a temperature lower than the crystallization temperature, it does not become crystalline and the characteristics of the amorphous alloy are not impaired.

[Brief description of drawings]

The drawings all show examples of the present invention, and FIG. 1 shows a situation in which the dimensional change of Co ₇₅ Si ₁₀ B ₁₅ amorphous alloy under tensile stress changes with the holding temperature. Graphs, FIGS. 2 and 3 are graphs showing the relationship between the chemical composition of the Co—Si—B system amorphous alloy and the crystallization temperature Tx, the vitrification transition temperature Tg, and the secondary dimensional change rate α ₂ . FIG. 4 is a graph showing the relationship between the Fe content of the Co—Fe—Si—B system amorphous alloy and the crystallization temperature Tx, the vitrification transition temperature Tg, and the secondary dimensional change rate α _2, and FIG. FIG. 3 is a partially cutaway elevational view schematically showing a main part of an embodiment of a first step of the invention. In the reference numerals shown in the drawings, 1 ... crucible 2 ... molten metal 3 ... nozzle 4 ... roll pair 4a, 4b ... roll 5 ... cooling jacket 6 ... molten metal drop 8 ... non Crystalline metal powder 9 ... It is a container.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ken Masumoto, 3-8-22 Uesugi, Sendai City, Miyagi Prefecture (72) Inventor, Kazuaki Fukando, 33-33 Yamada Jiyugaoka, Sendai City, Miyagi Prefecture (56) References 53-100905 (JP, A) JP-A-60-121203 (JP, A)

Claims (1)

[Claims] 1. An amorphous process comprising the steps of producing an amorphous alloy powder and molding the amorphous alloy powder alone at a temperature in the range above the glass transition temperature and below the crystallization temperature. For manufacturing a high quality alloy compact.