JPS6386805A - Production of amorphous alloy powder - Google Patents

Abstract

PURPOSE:To obtain amorphous alloy powder which is particularly excellent for powder metallurgy and catalyst or as a raw material for a composite material by absorbing hydrogen into a thin amorphous alloy strip manufactured by a quick liquid cooling method, then pulverizing the alloy to powder. CONSTITUTION:The thin amorphous strip is formed by the quick liquid cooling method; i.e., by supplying a molten alloy continuously from a pouring nozzle onto a cooling roll rotating at a high speed and quickly cooling the molten alloy on the surface of said roll to solidify. The thin amorphous alloy strip is then cathodically reduced in an electrolyte soln., by which the strip is subjected to an embrittlement treatment to absorb the hydrogen therein. The embrittled thin amorphous alloy strip is thereafter pulverized to the powder, by which the desired amorphous alloy powder is obtd. The powder is dehydrogenated by heating the powder at the crystallization temp. or below after the pulverization to obtain the amorphous alloy powder which does not contain the hydrogen in the case of using the powder in an application where the remaining of a slight amt. of the hydrogen in the alloy powder is not desired.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for producing amorphous alloy powder, particularly an amorphous alloy powder that is excellent for powder metallurgy, catalyst use, or as a raw material for composite materials. .

(Prior art) A method for producing amorphous alloy powder is disclosed in Japanese Patent Application Laid-open No. 57-29.
No. 505, a method is disclosed in which molten metal is injected through an orifice opening into a cooling fluid on the inner wall of a rotating cup for rapid solidification, and solid powder is subsequently recovered from the cooling fluid.

Furthermore, in JP-A No. 58-6907, two stages of rotating rolls, upper and lower, are provided, and molten metal is dropped into the single roll or twin rolls in the upper stage to break it into droplets, and the separated droplets are released at high speed by centrifugal force. A method is disclosed for producing amorphous alloy powder by impinging a stream onto the surface of a lower tier of chilled rotating rolls for rapid solidification.

Furthermore, in Japanese Patent Publication No. 60-401, after producing a ribbon-shaped amorphous alloy, it is heat-treated at a temperature below the crystallization temperature to embrittle it without causing the formation of a crystalline phase, and then pulverized into powder. A method has been proposed.

(Problems to be Solved by the Invention) The method of JP-A No. 57-29505 has the disadvantage that the opening gradually melts and expands during long-term production, resulting in a change in the diameter of the produced powder. In addition, it was necessary to separate the produced powder from the cooling liquid.

Furthermore, the amorphous alloy powder obtained by the method of JP-A No. 58-6907 has a wide range of particle sizes, ranging from 20 to 500 μm, with considerable coarse particles mixed in, and the entire apparatus is heated in an inert gas atmosphere. The problem was that oxidation of the powder surface could not be prevented unless it was covered with.

Furthermore, the method disclosed in Japanese Patent Publication No. 60-401 has the advantage that it is possible to ensure a high degree of amorphism because the ribbon is produced in the first step, and that powder with 100% amorphous phase can be produced. On the other hand, it required complicated steps such as heat treatment for embrittlement in the second step.

(Means for Solving the Problems) The present invention aims to provide a manufacturing method that can eliminate and improve the above-mentioned problems of the prior art, and the scope of the claims is as follows: The above object can be achieved by providing the second manufacturing method. That is, the present invention includes 1. subjecting an amorphous alloy ribbon produced by a liquid quenching method to hydrogen absorption embrittlement treatment to absorb hydrogen into the amorphous alloy ribbon, and then pulverizing it into a powder form. A method for producing an amorphous alloy powder characterized by:

2. The method for producing an amorphous alloy powder according to claim 1, wherein the hydrogen absorption embrittlement treatment is performed by subjecting the amorphous alloy ribbon to a cathodic reduction treatment in an electrolyte solution.

3. The amorphous alloy ribbon produced by the liquid quenching method is subjected to hydrogen absorption embrittlement treatment to absorb hydrogen into the amorphous alloy ribbon, and then pulverized into powder and further subjected to dehydrogenation treatment. The present invention relates to a method for producing an amorphous alloy powder, which is characterized in that the present invention comprises the steps of:

Next, the present invention will be explained in detail.

The present invention utilizes a liquid quenching method in the first step, in which molten alloy is continuously supplied from a pouring nozzle to the surface of a cooling roll rotating at high speed, and is rapidly solidified on the surface of the roll to form an amorphous alloy ribbon. The amorphous alloy ribbon is then cathodically reduced in an electrolyte solution, subjected to an embrittlement treatment to absorb hydrogen, and the embrittled amorphous alloy ribbon is pulverized into powder. When using the crystalline alloy powder for applications where it is not desirable for a small amount of hydrogen to remain in the 0 alloy powder, it may be dehydrogenated to contain hydrogen by heating below the crystallization temperature after pulverization. It is possible to produce a non-amorphous alloy ribbon.

As the embrittlement treatment of the amorphous alloy ribbon, for example, by electrolyzing the amorphous alloy ribbon in an electrolyte solution using the amorphous alloy ribbon as a cathode, hydrogen is generated on the ribbon surface, and the hydrogen of 50 to 200 ρpa1 is The ribbon becomes brittle by being absorbed into the ribbon. Here, the reason why we adopted the method of absorbing hydrogen into the ribbon is that the atomic arrangement of amorphous alloys is disordered, the density is lower than that of crystalline alloys, and the gaps between atoms are large, so it is easy to absorb hydrogen. It is from. The present invention is characterized in that this embrittlement treatment with hydrogen is applied to an amorphous alloy ribbon and used as a pretreatment means for pulverizing the amorphous alloy ribbon into powder having an appropriate particle size.

Note that as a hydrogen absorption embrittlement treatment method, in addition to the treatment in the electrolyte solution described above, acid treatment, heating in H2 gas, etc. can be adopted.

Next, a method for manufacturing an amorphous alloy powder according to the present invention will be specifically explained.

A molten alloy having a composition of FetqBBS1sG+ is injected onto the surface of a copper alloy cooling roll using an internal forced water cooling system through the slit-shaped opening of a pouring nozzle, and rapidly solidified to form a sheet with a thickness of 25μ.
An amorphous alloy ribbon with a thickness of 100 mm and a thickness of 100 mm in the plate was prepared.

The amorphous alloy ribbon was found to be amorphous with no crystal phase peak detected by chi-ray diffraction, and it did not crack during 180 degree tight bending and had excellent toughness. Therefore, an attempt was made to crush the amorphous alloy thin strip in this state in a ball mill, but it could hardly be crushed.

In an LN H, SO, aqueous solution, the amorphous alloy ribbon was used as a cathode and the platinum plate was used as a counter electrode, and electricity was applied at room temperature for 10 minutes to absorb about 150 ppa+ hydrogen and perform embrittlement treatment.
After electrolytic treatment, the amorphous alloy ribbon became brittle and could no longer withstand 180-degree bending. No crystal phase peak was detected by X-ray diffraction, and it was confirmed that the material was amorphous.

When an amorphous alloy thin strip subjected to hydrogen embrittlement treatment was placed in a ball mill and operated for 2 hours, the average powder diameter was about 50 tt m. Any known means such as a ball mill, a crusher mill, and a hammer mill can be used to crush the embrittled amorphous alloy thin strip. In order to reduce contamination of the powder by scratching force during the pulverization, it is desirable to use cemented carbide, ceramics, etc. for the worn portion of the means, or to apply a hard surface coating treatment. Furthermore, if surface oxidation becomes a problem during the pulverization process, it is desirable to pulverize in a neutral atmosphere such as nitrogen or argon, or in a vacuum.

When amorphous alloy powder is used as a raw material for powder metallurgy, the presence of hydrogen in the powder may impair the mechanical properties of the shaped and sintered material. Amorphous alloy powder used for such uses requires dehydrogenation treatment. As the dehydrogenation treatment, heat treatment, for example, is proposed in the present invention. More than 80% of the hydrogen absorbed in the amorphous alloy ribbon is released during the pulverization process, and it is more easily released by heating at 100 to 300°C. This hydrogen release is promoted by performing it in a neutral gas stream or in a vacuum. When using alloy powder to obtain a homogeneous composition or fine grain structure in powder metallurgy, etc., an amorphous structure is not necessarily required, so in that case, it is heated to a temperature higher than the crystallization temperature and dehydrogenated. can also be applied in a short period of time.

The shape of the amorphous alloy used in the present invention may be any of a strip, a ribbon, a filament, and a fiber.

Next, the present invention will be explained with reference to examples.

(Example 1) A molten alloy having a composition of Fet, B+zSiaC+ was injected through a pouring nozzle onto the surface of a cooling roll made of a Cu-Be alloy with internal forced water cooling, to produce an amorphous alloy ribbon with a thickness of 22 μm. The peripheral speed of the roll was 25 m/see, and the slit shape was 0.6 lMX 50 mm. In a zero-order IN H (J aqueous solution), which was confirmed to be amorphous by X-ray diffraction, a 3A current was applied to the ribbon at room temperature for 10 minutes using the amorphous alloy ribbon as a cathode and a platinum plate as a counter electrode. It was subjected to embrittlement treatment by absorbing about 100 ppn+ of hydrogen.Then, it was roughly crushed in an iron mortar to form flakes of several nanometers square, and then crushed in an alumina ball mill for 3 hours. is about 35μm
An amorphous alloy powder was obtained.

(Example 2) A molten alloy having a composition of NiysB+5SLo was treated in the same manner as in Example 1 to produce an amorphous alloy ribbon with a thickness of 25 μm.The amorphous alloy was used as a cathode and a platinum plate in a 0-order lN NaOH aqueous solution. The thin strip was subjected to embrittlement treatment by applying a current of 5 A for 5 minutes and absorbing about 120 PP1L of hydrogen using the material as a counter electrode.
Next, the mixture was roughly crushed in an iron mortar, then crushed in a ball mill for 3 hours, and then heated at 250°C for 10 minutes to dehydrogenate. The average particle size of the obtained powder was about 40 μm, and it was confirmed by X-ray diffraction that it was amorphous.

(Comparative Example 1) Ni75BI5Sil obtained in Example 2. An attempt was made to crush the amorphous alloy ribbon in a mortar without subjecting it to embrittlement treatment using hydrogen, but it was not even possible to crush it into flakes.

The method for producing amorphous alloy powder according to the present invention according to the simple steps of rapid cooling casting, hydrogen absorption embrittlement treatment, and pulverization provides high amorphous dust, appropriate particle size, and easy control of Fn size distribution. We were able to produce an excellent amorphous alloy powder with high surface cleanliness.

(Effects of the Invention) According to the present invention, a material for powder metallurgy or composite material with high amorphous dust, appropriate particle size, easy control of particle size distribution, and high surface cleanliness can be obtained through a simple process. It can be used to produce excellent amorphous alloy powder, and its effects are great.

Claims (1)

[Claims] 1. Hydrogen absorption embrittlement treatment is applied to an amorphous alloy ribbon produced by a liquid quenching method to absorb hydrogen into the amorphous alloy ribbon, and then pulverized into powder. A method for producing an amorphous alloy powder, characterized by: 2. The method for producing an amorphous alloy powder according to claim 1, wherein the hydrogen absorption embrittlement treatment is performed by subjecting the amorphous alloy ribbon to a cathodic reduction treatment in an electrolyte solution. 3. The amorphous alloy ribbon produced by the liquid quenching method is subjected to hydrogen absorption embrittlement treatment to absorb hydrogen into the amorphous alloy ribbon, and then pulverized into powder and further subjected to dehydrogenation treatment. A method for producing an amorphous alloy powder, the method comprising: