JP6406156B2 - Method for producing water atomized metal powder - Google Patents

Description

  The present invention relates to a method for producing metal powder (hereinafter, also referred to as water atomized metal powder) using a water atomizer, and more particularly to a method for improving the amorphization rate of water atomized metal powder.

  Conventionally, there is an atomizing method as a method for producing metal powder. The atomizing method includes a water atomizing method in which a metal powder is obtained by injecting a high-pressure water jet into a molten metal flow, and a gas atomizing method in which an inert gas is injected in place of the water jet.

  In the water atomization method, the flow of the molten metal is divided by a water jet sprayed from a nozzle, and the molten metal (powdered metal (metal powder)) divided by the water jet is also cooled to obtain an atomized metal powder. Yes. On the other hand, in the gas atomization method, the flow of molten metal is divided by an inert gas jetted from a nozzle to form powdered metal, and then the powdered metal is usually used in a water tank or flowing water provided under the atomizer. The powder metal (metal powder) is cooled down to obtain an atomized metal powder.

  In recent years, from the viewpoint of energy saving, for example, a reduction in iron loss and a reduction in size of a motor core used in an electric vehicle and a hybrid vehicle have been demanded. Conventionally, a motor core has been manufactured by laminating electromagnetic steel plates, but recently, a motor core manufactured using metal powder (electromagnetic iron powder) having a high degree of freedom in shape design has attracted attention. In order to reduce the iron loss of such a motor core, it is necessary to reduce the iron loss of the metal powder used. In order to obtain a metal powder with low iron loss, it is effective to make the metal powder amorphous. However, in order to obtain an amorphous metal powder by the atomization method, it is necessary to prevent crystallization by supercooling and solidifying a metal powder in a high temperature state including a molten state.

  In producing metal powder, the water atomization method is said to be a production method that is higher in productivity and cheaper than the gas atomization method. Furthermore, the metal powder produced by the water atomization method is indefinite, and the powder is more likely to get entangled during compression molding compared to the spherical metal powder produced by the gas atomization method, and the strength after compression molding is increased. is there. However, in the water atomization method, when water is sprayed on a high-temperature molten metal, if water contacts the high-temperature molten metal, it instantly evaporates on the surface of the metal powder (droplet) containing the molten state. A vapor film is formed. The vapor film formed on the surface prevents direct contact between the droplet and the cooling water, resulting in a so-called film boiling state. Therefore, the water atomization method has a problem that it is difficult to increase the cooling rate of the metal powder including the molten state.

  By the way, recently, as described in Non-Patent Document 1, heat treatment is performed on an amorphous alloy produced by quenching to refine crystal grains to about 10 nm and realize excellent soft magnetic properties. Nanocrystalline soft magnetic alloys said to have been found. As a typical Fe-based nanocrystalline soft magnetic alloy, for example, an Fe—Cu—Nb—Si—B alloy in which Nb and Cu are added to an Fe—Si—B composition is known. Further, there is known an Fe-MB alloy in which B is added to an Fe-M amorphous alloy and simultaneously exhibits high saturation magnetic flux density and excellent soft magnetic properties.

  Non-Patent Document 2 describes a soft magnetic heteroamorphous alloy. These alloys are alloys in which P and Cu are added to the Fe-Si-B composition, have a nano-heterostructure in which fine α-Fe crystals are dispersed in an amorphous matrix, and are highly saturated. And excellent soft magnetism. However, in order to obtain a high saturation magnetic flux density, it is directed to increase the ratio of Fe (including Ni and Co substituted for Fe). It is said that as the amount of Fe, Ni and Co increases, the cooling rate required for amorphization also increases.

  For this reason, several methods for rapidly cooling the metal powder have been proposed.

For example, Patent Document 1 describes a method for producing a metal powder in which the cooling rate until solidification is 10 ⁵ K / s or more when a metal powder is obtained by cooling and solidifying while scattering molten metal. . In the technique described in Patent Document 1, the above-described cooling rate is obtained by bringing the scattered molten metal into contact with the coolant flow generated by swirling the coolant along the inner wall surface of the cylindrical body. It is supposed to be done. The flow rate of the coolant flow generated by swirling the coolant is preferably 5 to 100 m / s.

  Patent Document 2 describes a method for producing rapidly solidified metal powder. In the technique described in Patent Document 2, the cooling liquid is supplied from the outer peripheral side of the upper end of the cylindrical portion of the cooling container whose inner peripheral surface is a cylindrical surface, and is allowed to flow down while swirling along the inner peripheral surface of the cylindrical portion, A layered swirl cooling liquid layer having a cavity at the center is formed by the centrifugal force generated by the swirl, and a molten metal is supplied to the inner peripheral surface of the swirl cooling liquid layer to rapidly cool and solidify. Thereby, it is said that the cooling efficiency is good and a high-quality rapidly solidified powder can be obtained.

  Patent Document 3 discloses a gas jet nozzle for injecting a gas jet onto a flowing molten metal to divide it into droplets, and a cooling cylinder having a cooling liquid layer flowing down while turning to the inner peripheral surface. An apparatus for producing metal powder by a gas atomizing method is provided. According to the technique described in Patent Document 3, the molten metal is divided into two stages by a gas jet nozzle and a swirling cooling liquid layer, and a finely cooled rapidly solidified metal powder is obtained.

  Further, in Patent Document 4, molten metal is supplied into a liquid refrigerant, a vapor film that covers the molten metal is formed in the refrigerant, and the resulting vapor film is collapsed so that the molten metal and the refrigerant are in direct contact with each other. A method for producing amorphous metal fine particles is described in which boiling due to natural nucleation is generated and the molten metal is rapidly cooled and amorphized by using the pressure wave to form amorphous metal fine particles. The collapse of the vapor film covering the molten metal can be achieved by bringing the temperature of the molten metal supplied to the refrigerant into direct contact with the refrigerant so that the interface temperature is lower than the film boiling lower limit temperature and higher than the spontaneous nucleation temperature or is irradiated with ultrasonic waves. Or that is possible.

  Further, in Patent Document 5, when the molten material is supplied as a droplet or a jet flow into the liquid refrigerant, the temperature of the molten material is directly brought into contact with the liquid refrigerant. It is set so that it is in a molten state above the production temperature, and the relative speed difference between the speed of the molten material and the speed of the liquid refrigerant flow when entering the liquid refrigerant flow is 10 m / s or more. Thus, there is described a method for producing fine particles in which a vapor film formed around a melted material is forcibly collapsed to cause boiling by spontaneous nucleation, which is atomized and cooled and solidified. As a result, even materials that were difficult in the past can be made fine and amorphous.

  In Patent Document 6, a raw material obtained by adding a functional additive to a base material is melted and supplied into a liquid refrigerant so that it is refined by vapor explosion and cooled at the time of solidification by cooling. The step of obtaining homogeneous functional fine particles that are polycrystalline or amorphous without segregation by controlling the amount of the particles, and the step of obtaining functional members by solidifying the functional fine particles and the fine particles of the base material as raw materials The manufacturing method of the functional member which comprises these is described.

Patent Document 7 describes a method for producing an amorphous alloy powder. In the technique described in Patent Document 7, the molten metal is flown from the pores and sprayed with a high-speed liquid, and the molten metal is pulverized and rapidly solidified to form an amorphous alloy powder. place the suction tube around the locations are to be sucked at a pressure differential of 20mmH ₂ O~200mmH _{2 O.} As a result, an alloy powder that is completely amorphous and irregularly shaped can be obtained.

Patent Document 8 describes a method for producing an amorphous alloy powder. In the technique described in Patent Document 8, the molten alloy is flown down from the pores, the high-speed liquid is sprayed on the molten molten metal, the molten metal is pulverized and rapidly solidified, and the molten metal is pulverized. A suction tube is arranged around the location and sucked with a pressure difference of ₂₀ mmH ₂ O to 200 mmH ₂ O, and a powder receiver is placed under the suction tube to temporarily solidify the amorphous powder. The method includes a step of applying the powder to a powder receiver, and a step of dropping the amorphous powder into a tank containing a liquid after being applied to the powder receiver. Due to the decompression action of this suction tube, the high-speed liquid acts more strongly on the alloy powder, making the powder irregular, destroying the vapor film formed around the powder, and significantly increasing the cooling rate of the powder. All of the above are irregularly shaped and made of an amorphous single phase, and an amorphous alloy powder that can be compacted is obtained.

  Patent Document 9 describes a method for producing an amorphous alloy powder. In the technique described in Patent Document 9, the molten metal is flown from the pores and sprayed with a high-speed liquid, and the molten metal is pulverized and rapidly solidified to form an amorphous alloy powder. A cooling block having a conical upper portion is arranged immediately below the location, and the powdered particles are applied to the cooling block. As a result, the cooling rate of the pulverized alloy powder can be increased and the vapor film generated around the powder can be broken to significantly increase the cooling rate of the powder.

  Patent Document 10 describes a metal powder manufacturing apparatus. The metal powder manufacturing apparatus described in Patent Document 10 includes a supply unit that supplies molten metal, and a liquid ejecting unit that includes a flow path through which the molten metal can pass and an orifice that ejects liquid into the flow path. , A traveling direction changing means for forcibly changing the traveling direction of the dispersion liquid is provided below the liquid ejecting unit, and the molten metal is brought into contact with the liquid ejected from the orifice, so that the molten metal is converted into a large number of fine droplets. The liquid droplets are divided and transferred as a dispersion in which the droplets are dispersed in a liquid, and the droplets in the dispersion are cooled and solidified to produce an amorphous metal powder. The traveling direction changing means to be used has a nozzle for injecting the second liquid, and means for injecting the second liquid from the nozzle toward the dispersion liquid to make it collide, or in the middle of the longitudinal direction is an arc shape And a means for forcibly changing the advancing direction of the dispersion along the inner wall surface of the curved portion, thereby forming a vapor layer formed around the powder. It is said that it can be reliably separated and a large number of powders can be cooled uniformly. Patent Document 10 shows that a fine amorphous metal powder having a particle size of about 3 μm can be produced. However, in the metal powder having a coarser particle diameter, the amorphous ratio is lowered.

In addition, as an example of an alloy composition serving as a starting material for obtaining an Fe-based nanocrystalline alloy having a high saturation magnetic flux density and excellent soft magnetic properties, for example, Patent Document 11 discloses an amorphous phase as a main phase. in formula has a _{Fe a B b Si c P x} C y Cu z, a: 79~86at%, b: 5~13at%, c: 0~8at%, x: 1~8at%, y The alloy composition is described as follows: 0-4 at%, z: 0.4-1.4 at%. This alloy composition has an amorphous phase as a main phase, and exhibits a nanoheterostructure composed of an amorphous phase and initial microcrystals present in the amorphous phase. Moreover, when heat-treating these alloy compositions, nanocrystals composed of bccFe phases can be precipitated, and Fe-based nanocrystal alloy powders having a high saturation magnetic flux density can be obtained.

Patent Document 12 discloses an alloy composition of the composition formula Fe _{(100-X—Y—Z)} B _X P _Y Cu _Z whose main phase is an amorphous phase, and X, Y, and Z are 100-X—. An alloy composition satisfying YZ: 79 to 86 at%, X: 4 to 13 at%, Y: 1 to 10 at%, and Z: 0.5 to 1.5 at% is described. In this alloy composition, a part of Fe may be substituted with one or more elements of Co and Ni. Fe element is an element responsible for magnetism, and it is preferable to increase the proportion of Fe element to improve the saturation magnetic flux density. This alloy composition has an amorphous phase as a main phase, and can also be made into an alloy powder exhibiting a nanoheterostructure consisting of an amorphous phase and initial microcrystals present in the amorphous phase. And when heat-treating these alloy compositions, it is said that nanocrystals consisting of bccFe phase can be precipitated, and Fe-based nanocrystal alloy powder with high saturation magnetic flux density can be obtained.

Although not a powder, as an amorphous alloy composition, for example, Patent Document 13, an amorphous alloy composition _{Fe a B b Si c P x} Cu y, a: 73~85at%, b: 9.65~22at%, An alloy composition is described in which b + c: 9.65 to 24.75 at%, x: 0.25 to 5 at%, y: 0 to 0.35 at%, y / x: 0 over 0.5.

Although not a powder, as an amorphous alloy composition, Patent Document 14, an amorphous alloy composition _{Fe a B b Si c P x} Cu y, a: 73~85at%, b: 9.65~22at%, b + c An alloy composition in the form of a ribbon is described, wherein: 9.65 to 24.75 at%, x: 0.25 to 5 at%, y: 0 to 0.35 at%, and y / x: 0 to 0.5 at%.

JP 2010-150587 Japanese Patent Publication No.7-107167 Japanese Patent No. 3932573 Japanese Patent No. 3461344 Japanese Patent No.4793872 Japanese Patent No. 4784990 Japanese Patent Publication No. 03-66361 Japanese Patent Publication No. 03-68922 Japanese Patent Publication No.61-401 JP 2007-291454 A Japanese Patent No. 4584350 Japanese Patent No. 4815014 Japanese Patent No. 4288687 Japanese Patent No. 4310480

Akihiro Makino, Katsuhito Yoshizawa: Materia, vol.14, No.6, P.392 Akihiro Makino et al .: Journal of Applied Physics, 105,013922 (2009)

  However, in the techniques described in Patent Documents 1 to 3, the divided molten metal is supplied into the cooling liquid layer formed by swirling the cooling liquid, and the vapor film formed around the metal particles is peeled off. However, when the temperature of the divided metal particles (molten metal) is high, film boiling tends to occur in the cooling liquid layer, and the metal particles (molten metal) supplied to the cooling liquid layer are the cooling liquid. Because it moves with the layer, the relative velocity difference between the metal particles (molten metal) and the coolant layer is small, making it difficult to peel off the vapor film and avoid film boiling, and is therefore necessary for amorphization There was a problem that a sufficient cooling rate could not be secured.

  Moreover, in the technique described in patent documents 4-6, the vapor | steam film | membrane which covers a molten metal is collapsed using the vapor explosion from a film | membrane boiling state to a nucleate boiling state in a chain, refinement | miniaturization of a metal particle, Furthermore, it intends to make it amorphous. It can be said that removing the vapor film in the film boiling state using the vapor explosion is an effective method. However, in order to cause a vapor explosion from the film boiling state to the nucleate boiling state, at least, First, it is necessary to cool the surface temperature of the metal particles to the minimum heat flow point or below, and if the surface temperature of the metal particles is high, cooling to the minimum heat flow point or below becomes the cooling in the film boiling region. Since the cooling is weak, there is a problem that the cooling rate for amorphization is insufficient.

  In the techniques described in Patent Documents 1 to 6, metal powder is manufactured using a gas atomization method, but it can be said that rapid cooling with cooling water after gas atomization is likely to make amorphous. However, in the gas atomization method, a large amount of inert gas is required for atomization, so that there is a problem that the manufacturing cost increases. Therefore, it is advantageous to use the water atomization method from the viewpoint of productivity.

  On the other hand, in the water atomization method, jet water (water jet) is jetted into a molten metal stream, and the molten metal stream is divided into metal powder. The atomized (molten metal stream) is surrounded around the divided metal particles. The water used for the splitting is present, making it easy to form a vapor film on the surface of the metal particles. For this reason, the cooling rate decreases and gradually cools, and it becomes impossible to achieve the cooling rate required to make the metal powder amorphous. Therefore, removal of the vapor film is an important issue in the water atomization method.

With respect to such problems, in the technique described in Patent Documents 7 and 8, by placing the suction tube around a portion of powdering the melt by suction at a pressure differential of 20mmH ₂ O~200mmH _{2 O} It is said that the irregularity of the metal particles and the vapor film formed around the metal particles can be removed. However, if moisture is present around the high-temperature metal particles, the water is also sucked together with the high-temperature metal particles, and the moisture is vaporized by the retained heat to form a vapor film on the metal particle surface again. It is thought that removal of the film becomes difficult.

  Further, in the technique described in Patent Document 9, if the temperature of the particles after pulverization is high, the surrounding cooling water is vaporized and forms a vapor film on the particle surface again. There is a problem that it cannot be said. On the other hand, if the temperature of the particles after pulverization is too low, there is a problem that when colliding with the cooling block, the particles are solidified and crystallization is likely to proceed.

  Further, in the technique described in Patent Document 10, the dispersion liquid whose traveling direction is forcibly changed by the traveling direction changing means is removed from the vapor film, but when the dispersion liquid temperature is high, it exists in the surroundings. There is a possibility that a vapor film is formed again due to the moisture. On the other hand, when the temperature of the dispersion liquid is low, there is a problem that the second liquid (water) from the traveling direction changing means causes solidification to proceed and crystallization proceeds.

  Thus, it is difficult to say that the vapor film formed on the surface of the metal powder is sufficiently removed by the water atomization method in the above-described prior art. Therefore, depending on the above-described prior art, the water atomized metal particles are not completely removed. The problem remains that it is difficult to ensure the cooling rate required for crystallization (amorphization).

  Therefore, the present invention can achieve high a cooling rate for breaking the vapor film formed on the surface and making it amorphous in the production of water atomized metal powder, and achieving the amorphousization of the metal particles. An object of the present invention is to provide a method for producing water atomized metal powder. Furthermore, the present invention can be expected to have a high saturation magnetic flux density, which has been difficult to be amorphous in the prior art, and the ratio of Fe atoms (including those in which part of Fe atoms are replaced by Ni and Co) is increased. In a base-based amorphous alloy (Fe-based soft magnetic alloy), for example, even a metal powder having a relatively large particle size with an average particle size of 5 μm or more should be a water atomized metal powder having a high amorphization rate Another object is to provide a method for producing a water atomized metal powder.

  The “metal powder having a high amorphization ratio” herein refers to a metal powder having an amorphization ratio of 90% or more.

  The “amorphization rate” was determined by measuring the halo peak from amorphous (amorphous) and the diffraction peak from crystal by X-ray diffraction method, and calculating the amorphization rate by WPPD method. The “WPPD method” here is an abbreviation for Whole-powder-pattern decomposition method. The WPPD method is detailed in Hideho Toraya: Journal of the Crystallographic Society of Japan, vol.30 (1988), No. 4, P253-258.

  In order to achieve the above-mentioned object, the present inventors diligently studied a method for removing a vapor film formed on the surface of a molten metal droplet divided in the water atomization method. As a result, the present inventors have come up with the idea of using water cooling (secondary cooling) in addition to primary cooling for blowing a water jet (jet water) to the molten metal flow and dividing the molten metal flow. . However, even if strong secondary cooling is applied, the vapor film cannot be removed, and instead the particle surface is covered with the vapor film, and the cooling rate required for amorphization cannot be secured, or the metal powder crystals I found out that there is a possibility that the process will progress.

  As a result of further studies, it was found that the timing of starting secondary cooling is important. The start timing of the secondary cooling is shown in FIG. 1 in relation to the temperature of the divided molten metal droplet and the solidification start temperature of the molten metal (hereinafter also referred to as the solidification start point).

  In the secondary cooling after the primary cooling for dividing the molten metal flow, as shown in FIG. 1 (a), the temperature of the divided molten metal droplets is within the range of the solidification start point to (solidification start point + 30 ° C.). At some point, it was found that the desired cooling rate required for amorphization of the metal powder can be ensured by starting without the deposition of a vapor film on the particle surface. Although the cause of this has not been clarified so far, the present inventors have confirmed that if the secondary cooling is started in this temperature range, the divided molten metal droplets solidify immediately, and after solidification. However, since the secondary cooling is continued, it is assumed that the impact force from the cooling water is easily transmitted to the vapor film formed on the surface, and the vapor film is easily broken and removed. Needless to say, the primary cooling for dividing the molten metal flow is performed in a liquid phase temperature range higher than the above-described secondary cooling start temperature.

  On the other hand, when the secondary cooling is started when the temperature of the divided molten metal droplet is within the temperature range shown in FIG. Even if it hits the cooling water, the droplets remain in a molten state, so that they are easily deformed and it is difficult to transmit the impact force to the vapor film, and the vapor film is not easily destroyed and is difficult to remove.

  Further, as shown in FIG. 1C, when the temperature of the divided molten metal droplets deviates from the above temperature range and starts secondary cooling, solidification starts without removing the vapor film. Therefore, it is considered that the cooling rate is slow and crystallization proceeds, making it difficult to achieve the desired amorphization rate.

  For this reason, in the present invention, the secondary cooling is started when the divided molten metal droplets are still in a molten state but at a temperature above the freezing point and in the vicinity thereof.

  Furthermore, the present inventors performed such secondary cooling on the divided molten metal droplets, thereby making it possible to produce an amorphous alloy powder that has been conventionally difficult to produce (part of Fe). (Including those in which Ni and Co are substituted for Ni) Co.) It is also possible to easily produce water atomized metal powder with high amorphization rate even in high Fe-based amorphous alloys (Fe-based soft magnetic alloys) I found it.

The present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
(1) In a method for producing a water atomized metal powder, water is injected into a flowing molten metal stream, the molten metal stream is divided to form molten metal droplets, and further cooled to form a water atomized metal powder. Secondary cooling jet water is sprayed onto the molten metal droplet at a position where the temperature of the molten metal droplet falls within the range of the solidification start point to (solidification start point + 30 ° C.). A method for producing water atomized metal powder, characterized in that secondary cooling comprising water cooling is started.
(2) In (1), the water cooling for injecting the secondary cooling jet water is a secondary cooling comprising water cooling nozzles arranged in a plurality of stages so as to be switchable in the dropping direction of the molten metal droplets. Among the means, a secondary cooling means capable of injecting the secondary cooling jet water at a position where the temperature of the molten metal droplet is not lower than the solidification start point (solidification start point + 30 ° C.) is selected. A method for producing water atomized metal powder, characterized in that
(3) In (1) or (2), the temperature of the molten metal droplet in the middle of dropping is measured by measuring the temperature of the molten metal flow before the division, and the obtained molten metal flow before the division is obtained. A method for producing water atomized metal powder, characterized in that an estimated value is used by heat transfer calculation based on temperature.
(4) In any one of (1) to (3), the spray water for dividing the molten metal flow is water temperature: 50 ° C. or less, spray pressure: water of 10 MPa or more, and water cooling of the secondary cooling is: A method for producing a water atomized metal powder, characterized by using water having a water temperature of 30 ° C. or less and an injection pressure of 10 MPa or more.
(5) In any one of (1) to (4), the molten metal is a Fe-based soft magnetic alloy composition or a Fe-based soft magnetic alloy composition in which a part of Fe is substituted with Ni and / or Co, A method for producing a water atomized metal powder, characterized by having an alloy composition in which the Fe-based element ratio, which is the total amount of Fe or Fe, Ni, and Co, is more than 82.5 at% and less than 86 at%.
(6) Water atomization characterized by subjecting the water atomized metal powder produced by the method for producing water atomized metal powder described in (5) to heat treatment at a temperature in the range of 400 to 500 ° C. A method for producing metal powder.
(7) A water atomized Fe-based soft magnetic alloy powder produced by the method for producing a water atomized metal powder according to (5), having an average particle size of 5 μm or more and an amorphization ratio of 90% or more.
(8) A water atomized Fe-based soft magnetic alloy powder produced by the method for producing a water atomized metal powder according to (6), having a nanocrystalline structure and having a high saturation magnetic flux density.

  According to the present invention, it is possible to rapidly cool water atomized metal powder having a high amorphization rate, which is advantageous for the production of amorphous metal powder, enables rapid cooling, and is advantageous for the production of dust cores. In addition, it can be manufactured stably and has a remarkable industrial effect.

  Further, according to the present invention, even in the Fe-based soft magnetic alloy powder in which the ratio of Fe (including Ni and Co in which part of Fe is substituted), which has been difficult in the past, is increased to more than 82.5 at%, the average grain size There is also an effect that even a large powder having a diameter exceeding 5 μm can be made into a powder having a high amorphization rate. In addition, there is also an effect that a nanocrystalline soft magnetic material (powder) having a high saturation magnetic flux density can be obtained only by subjecting the water atomized soft magnetic alloy powder obtained in the present invention to further appropriate heat treatment.

It is explanatory drawing which shows the outline | summary of this invention typically. It is explanatory drawing which shows typically an example of schematic structure of the water atomized metal powder manufacturing apparatus suitable for implementation of this invention. It is explanatory drawing which shows an example of the procedure for calculating the droplet temperature (estimation) of the divided molten metal.

  In the present invention, first, a metal material as a raw material is melted to form a molten metal. As the metal material used as the raw material, any of pure metals, alloys, cast irons and the like conventionally used as iron powder can be applied. Examples thereof include iron-based alloys such as pure iron, low alloy steel and stainless steel, non-ferrous metals such as Ni and Cr, non-ferrous alloys, and amorphous alloys (amorphous alloys).

  In addition, as an amorphous alloy (amorphous alloy), Fe, B, C, P, Si, Cu, Nb, and Cr are the main constituent elements, and if at% or less is about 1% or less, Ti, Zr Alloys with compositions that allow mixing of Hf, Nb, Ta, Mo, W, Al, Mn, Ag, Zn, Sn, As, Sb, Bi, Y, N, O, S, H, etc. are known. Yes. A part of Fe can be replaced by Ni or Co. In the present invention, any of these amorphous alloys (amorphous alloys) can be applied.

  Examples of the iron-based amorphous alloy mainly include Fe, for example, Fe-B alloy, Fe-Si-B alloy, Fe-Cu-Nb-Si-B alloy, Fe-Nb-B alloy, Fe -Ni-B alloy, Fe-BP-Cu alloy, Fe-BP-Cu-Cr alloy, etc. can be illustrated. Needless to say, the above alloy may contain an element other than the above element as an impurity.

  In addition, the present invention can also be applied to iron-based soft magnetic alloys that have recently attracted attention and are expected to have a high saturation magnetic flux density. In particular, an iron-based soft magnetic alloy in which the Fe ratio, or the ratio of Fe, Ni, and / or Co when a part of Fe is substituted with Ni and / or Co is more than 82.5 at% and less than 86% is also applicable.

More specifically, Fe ₈₃ B ₁₇ and Fe ₈₅ B ₁₅ can be exemplified as the Fe—B alloy, and Fe ₇₉ Si ₁₀ B ₁₁ and Fe ₇₇ Si ₁₁ B ₁₂ can be exemplified as the Fe—Si—B alloy. An example of the Fe—BP—Cu—Cr alloy is Fe _83.1 B ₁₀ P ₆ Cu _0.7 Cr _0.2 .

As the Fe-B-P-Cu alloy, an alloy composition of the formula _{Fe (100-X-Y-} Z) B X P Y Cu Z, X, Y, Z are, (100-X-Y- Z): more than 82.5 at% and less than 86 at%, X: 4 to 13 at%, Y: 1 to 10 at%, Z: 0.5 to 1.5 at%, or a part of the Fe among Ni and Co An alloy composition formed by substitution with one or more elements can be exemplified. Further, in the alloy composition of the formula _{Fe a B b Si c P x} C y Cu z, a: 82.5at% greater than less than 86at%, b: 5~13at%, c: 0~8at%, x: 1~8at %, Y: more than 0 to 5 at%, z: 0.4 to 1.4, or a composition obtained by substituting a part of Fe with one or more elements of Ni and Co. In the present invention, in the above-described Fe-based amorphous alloy, even in a composition in which the content of Fe (including Ni in which part of Fe is substituted, including Co) exceeds 82.5 at%, It can be sufficiently amorphous.

  The method for melting the metal material to be used is not particularly limited, and any conventional melting means such as an electric furnace or a vacuum melting furnace can be applied.

  The melted molten metal is transferred from the melting means to a molten metal holding container such as a tundish, and is made into water atomized metal powder in the water atomized metal powder production apparatus. An example of a preferable water atomized metal powder production apparatus used in the present invention is shown in FIG.

  Hereinafter, the present invention will be described with reference to FIG. 2A shows the configuration of the entire apparatus, and FIG. 2B shows the details of the water atomized metal powder production apparatus 14.

  The molten metal 1 flows down from the molten metal holding container 3 such as a tundish as a molten metal flow 8 into the chamber 9 through the molten metal guide nozzle 4. In addition, the inert gas valve | bulb 11 can be opened and the inside of the chamber 9 can also be made into inert gas atmosphere. Examples of the inert gas include nitrogen gas and argon gas.

  The molten metal stream 8 is sprayed with water (water jet) 7 through a water-cooled nozzle 6 disposed in the nozzle header 5 to divide the molten metal stream 8, and a large number of fine molten metals are formed. Let it be droplet 8a. In addition, the position A where the molten metal flow 8 and the jet water (water jet) 7 come into contact with each other is set to a position away from the molten metal guide nozzle 4 by an appropriate distance. This is preferable from the viewpoint of preventing contact.

  In the present invention, in order to divide the molten metal flow 8, if the injection water (water jet) 7 used is an injection water having an injection pressure that can divide the molten metal flow 8, the injection pressure and water temperature are Although not particularly limited, in order to make the divided molten metal droplets into fine droplets, it is preferable that the injection pressure is 10 MPa or more. The higher the injection pressure, the finer the molten metal droplets (the average particle diameter of the metal powder) that are divided. The water temperature is preferably 50 ° C. or lower, preferably 10 ° C. or lower from the viewpoint of promoting cooling in the secondary cooling and removing the vapor film.

  In addition, the cooling water used for the jet water 7 is heat exchange such as a chiller 16 that cools the cooling water to a low temperature in advance in a cooling water tank 15 (heat insulating structure) provided outside the water atomized metal powder production apparatus 14. It is preferable to store it as low-temperature cooling water in a vessel. Since a general cooling water production machine freezes the heat exchanger and it is difficult to generate cooling water of less than 3-4 ° C., a mechanism for replenishing ice into the tank by an ice production machine is provided. Also good. Further, the cooling water tank 15 is provided with a high-pressure pump 17 that boosts and sends the cooling water used for the jet water 7 and a cooling water pipe 18 that supplies the cooling water from the high-pressure pump to the nozzle header 5. Not too long.

  The water-cooled nozzle 6 may be a water-cooled nozzle that can sever the molten metal flow 8, and the type thereof is not particularly limited. In addition, it is preferable that a plurality of water cooling nozzles 6 are disposed on the same circumference, preferably 4 to 16, so that water can be sprayed uniformly over the entire circumference of the molten metal flow 8, or water is ejected from the slits. It is good also as an annular nozzle.

  In the present invention, first, at the position A as described above, the injection water 7 is injected into the flowing molten metal flow 8 to divide the molten metal flow 8. The divided molten metal droplets 8a are cooled by the jetted water 7 as primary cooling, and are cooled while falling together with the jetted water.

  In the present invention, after the primary cooling, the secondary cooling of the divided molten metal droplet 8a is started at the position B in the middle of the dropping. The secondary cooling start position B is a position where the temperature of the molten metal droplet 8a in the middle of dropping falls within the range of the solidification start point to (solidification start point + 30 ° C.).

  By starting the secondary cooling when the temperature of the divided molten metal droplet is in the range of the solidification start point to (solidification start point + 30 ° C.), there is no adhesion of a vapor film to the particle surface, A desired cooling rate necessary for amorphization of the metal powder can be ensured. When the temperature of the divided molten metal droplets is higher than the range of the solidification start point to (solidification start point + 30 ° C.), when secondary cooling is performed, a vapor film is formed and the desired cooling rate Cannot be secured. In addition, when secondary cooling is performed when the temperature of the divided molten metal droplet is lower than the range of the solidification start point to (solidification start point + 30 ° C.), crystallization proceeds until the secondary cooling is performed. The desired amorphization rate cannot be achieved.

  Therefore, in the present invention, the temperature of the molten metal droplet 8a in the middle of dropping is estimated, and the temperature of the molten metal droplet 8a in the middle of dropping is between the solidification start point and (solidification start point + 30 ° C.). A position B at which the temperature is within the range is calculated, and at that position B, a plurality of stages arranged in the dropping direction are arranged so that the water cooling of the secondary cooling can be started for the first time on the molten metal droplet 8a in the middle of dropping. The secondary cooling means 2j at an appropriate position is selected from the secondary cooling means 21 to 2i, and the selected secondary cooling means 2j (secondary cooling means 22 in the second stage in FIG. 2B) is selected. The secondary cooling jet water 20 is jetted to start secondary cooling. Needless to say, depending on the type of molten metal, the difference in solidification start temperature, and the difference in latent heat of solidification, the secondary cooling means in the downstream stage from the selected stage may be water-cooled at the same time. .

  Therefore, in carrying out the present invention, the water atomized metal powder production apparatus 14 to be used has a plurality of stages, preferably 3 to 10 stages of secondary cooling means 21 to 2i in the dropping direction of the molten metal droplet 8a. Is disposed. The secondary cooling means 21 to 2i at each stage are centered on the extension line of the molten metal flow center so that one water cooling nozzle or the falling molten metal droplet 8a can be uniformly cooled from the entire circumference. It is preferable to use a cooling means in which a plurality of about 2 to 4 are arranged on the same circumference. In addition, the water-cooling nozzles that are the secondary cooling means 21 to 2i are used for the secondary cooling jet water 20 to be jetted so that the secondary cooling can be started at the same temperature (at the same position) on the droplet 8a that is falling. It is preferable that the injection direction is adjusted in accordance with the type of the water cooling nozzle so that the upper surface is substantially parallel to the horizontal plane. In FIG. 2, the water cooling nozzles that are the secondary cooling means 21 to 2i are arranged so as to be in the injection direction (preferably 5 to 30 °) downward from the horizontal. For example, the upper surface of the secondary cooling water 20 can be made substantially parallel by disposing the water cooling nozzle 15 ° downward and setting the spray angle from the nozzle to 30 °.

  Needless to say, the secondary cooling means of each stage is arranged to be switchable so that it can be operated for each stage or simultaneously for a plurality of stages. Moreover, the form of the water cooling nozzle to be used is not particularly limited, and any conventional water cooling nozzle can be applied. Needless to say, the secondary cooling means 21 to 2i are respectively provided with secondary ON / OFF control of cooling and secondary cooling control valves 21a to 2ia that can adjust the amount of cooling water.

  Although it is difficult to actually measure the temperature of the molten metal droplet 8a during the fall, measure the peak value when passing in front of the sensor of the proximity fiber thermometer or measure the change in luminance. However, since the accuracy is low, it is preferable to perform the estimation through the following steps (see FIG. 3).

  First, the temperature of the flowing molten metal flow is measured by a thermometer 40 (molten metal flow thermometer) disposed at a predetermined position before dividing. Examples of the thermometer 40 include a thermocouple, a proximity fiber thermometer, and an infrared radiation thermometer. The temperature of the molten metal flowing down is preferably directly measured, but the temperature (estimated) at the temperature measurement position (thermometer placement position) calculated through steps 00 to 01 may be used.

In step 1 (STEP 1), the temperature change of the flowing molten metal flow is calculated. Using the measured molten metal flow temperature as an initial condition, unsteady heat conduction calculation using a cylindrical coordinate system is performed to determine the temperature of the molten metal flow flowing down at the primary cooling jet water injection position. The boundary condition is natural convection heat transfer (heat transfer coefficient of about 30 W / m ² K) considering heat radiation. It is preferable to use an emissivity of about 0.9. As the calculation time, a value obtained by dividing the distance from the temperature measurement position by the thermometer 40 to the primary cooling jet water injection position by the flow velocity of the molten metal flow is used.

  If the temperature of the flowing molten metal stream cannot be measured, although not shown in FIG. 3, step 00 (STEP 00) and step 01 (STEP 01) are performed, and the calculated thermometer position is calculated. Step 1 (STEP 1) may be executed by calculating the temperature (calculated value) of the molten metal flow and replacing the measured temperature of the molten metal flow.

  In step 00 (STEP 00), the temperature of the molten metal in the tundish (molten metal holding container) is used as an initial condition to perform unsteady heat conduction calculation using a cylindrical coordinate system, and the molten metal at the outlet of the molten metal guide nozzle 4 Determine the flow temperature. The boundary condition is contact heat conduction with the molten metal guide nozzle, and heat radiation is not considered. The calculation time is the passage time in the molten metal guide nozzle. Next, in step 01 (STEP 01), the temperature (average) of the molten metal flow at the outlet of the molten metal guide nozzle 4 is used as an initial condition, and unsteady heat conduction calculation is performed using a cylindrical coordinate system. The temperature of the flowing molten metal flow at the installation position is obtained. The boundary conditions are the same as in step 1.

Next, Step 2 (STEP 2) is performed. In step 2, the temperature change of the molten metal droplet divided by the primary cooling is calculated. Regarding the molten metal droplets divided by the injection of the primary cooling jet water using the temperature (average) of the molten metal flow flowing down at the primary cooling jet water injection position calculated in step 1 as the average temperature of the droplets as an initial condition The unsteady heat conduction calculation using the spherical coordinate system is performed. The boundary condition is forced heat transfer by water atomization (partition of molten metal flow by injection of primary cooling jet water), and heat transfer in a film boiling state (heat transfer coefficient 100 to 500 W / m ² K). Heat radiation is taken into account. The calculation time is obtained by dividing the distance from the start of primary cooling (primary cooling jet water injection) to the end by the droplet drop speed. Note that the droplet drop speed is the same as the cooling water drop speed (about 20 to 200 m / s).

  Next, Step 3 (STEP 3) is performed. In step 3, the temperature change due to the drop of the divided droplets to the secondary cooling start position is calculated. Using the droplet temperature at the end of primary cooling calculated in step 2 as an initial condition, unsteady heat conduction calculation using a spherical coordinate system is performed. Since the boundary condition is a state in which the droplets are falling together with the primary cooling water, the heat transfer by the falling water is performed and the heat transfer is performed under the film boiling condition. Heat radiation is also taken into account. The calculation time is obtained by dividing the distance from the primary cooling end position to the secondary cooling start position by the droplet dropping speed.

In step 4 (STEP 4), the temperature change of the droplet due to secondary cooling is calculated. In step 4 (STEP 4), unsteady heat conduction calculation using a spherical coordinate system is performed using the temperature (average) at the secondary cooling start position calculated in step 3 as an initial condition. The boundary condition is forced convection heat transfer by secondary cooling water injection, and after solidification, the temperature of the droplet (metal particles) is kept below the MHF point (minimum heat flux point), boiling from the film boiling state to the nucleate boiling state Calculate in response to changes in state. Heat transfer rate in the film boiling state is about 500 W / m ^{2 K} or so, is preferably about 10000 W / m ^{2 K} about the nucleate boiling state. Heat radiation is also taken into account. As the calculation time, a value obtained by dividing the distance from the secondary cooling start position to the end position by the droplet dropping speed is used.

  In the present invention, in Step 3 described above, the distance from the primary cooling end position to the secondary cooling start position is changed to calculate the temperature of the droplet at the secondary cooling start position, and the calculated temperature of the droplet However, the position which becomes the temperature in the range of the solidification start temperature (solidification start point) to (solidification start temperature (solidification start point) + 30 ° C.) is obtained and set as the secondary cooling start position.

  In the present invention, among the plurality of stages of secondary cooling means arranged in the direction in which the liquid drops fall, the liquid is arranged at a position that matches the calculated secondary cooling start position through steps 1 to 3. Secondary cooling is started using the secondary cooling means of the other stage.

  In the unsteady heat conduction calculation using the cylindrical coordinate system in the present invention, the following equation (1)

(Where T: temperature, t: time, r: radius, α: thermal diffusivity)
The following forward differential equation is derived from the heat balance of the i-th layer of radius i while changing from time to time t: P to P + 1.

{Π (nΔr + Δr / 2) ² −π (nΔr−Δr / 2) ² } × ρC _p × (T _n ^{P + 1} −T _n ^P ) / Δt
= 2π (nΔr−Δr / 2) · λ · (T _i-1 ^P −T _i ^P ) / Δr−2π (nΔr + Δr / 2) · λ · {T _i ^P −T _{i + 1} ^P } / Δr
Here, λ / ρC _p is the thermal diffusivity (m ² / s), the subscript n is the spatial address, and the superscript P is the time step.

  In the unsteady heat conduction calculation using the spherical coordinate system, the following equation (2)

(Where T: temperature, t: time, r: radius, α: thermal diffusivity)
The following forward differential equation is derived from the partial differential equation represented by

(T _n ^{P + 1} −T _n ^P ) / Δr
= Α {1 / n × ( T n + 1 P + 1 -T n-1 P) / (Δr) 2 + (T n + 1 P + 1 + T n-1 P -2T n P) / (Δr) ² }
Here, α (= λ / ρC _p ): thermal diffusivity (m ² / s), subscript n represents a spatial address, and superscript P represents a time step.

  In the secondary cooling in the present invention, it is preferable that the injection pressure of the secondary cooling jet water is 10 MPa or more and the secondary cooling jet is supplied through the water cooling nozzle (secondary cooling means).

  In the secondary cooling, in order to inject the secondary cooling jet water 20 and remove the vapor film covering the molten metal droplets, the secondary cooling injection pressure is preferably as high as possible, and preferably 10 MPa or more. When the secondary cooling injection pressure is less than 10 MPa, the vapor film cannot be sufficiently removed. The higher the secondary cooling injection pressure, the more advantageous, but in practice it is preferably 100 MPa or less. Moreover, it is preferable that the temperature of the cooling water used for secondary cooling shall be 30 degrees C or less from a viewpoint of acceleration | stimulation of cooling and vapor film removal. More preferably, it is 10 ° C. or lower. When the water temperature exceeds 30 ° C. and becomes high temperature, a vapor film is easily formed, and the cooling ability is reduced.

  The cooling water used for the secondary cooling water 20 is preliminarily stored in a cooling water tank 15 (heat insulating structure) provided outside the water atomized metal powder production apparatus 14 in the same manner as the cooling water used for the water 7. It is preferable to use stored cooling water. The cooling water tank 15 has a system separate from the cooling water used for the jet water 7 and a secondary cooling high pressure pump 37 for boosting and feeding the cooling water used for the secondary cooling jet water 20 and a secondary cooling high pressure. It goes without saying that a secondary cooling water pipe 38 for supplying cooling water from the pump 37 to the secondary cooling means 21 to 2 i which are water cooling nozzles is disposed. Note that a surge tank or the like may be provided in the middle of the piping to facilitate the sudden injection of high-pressure water. In addition, although the cooling water used for secondary cooling is not shown in FIG. 2, it is preferable from the viewpoint of droplet temperature adjustment to use cooling water of a different system from the primary cooling.

  Hereinafter, based on an Example, this invention is demonstrated further.

  Metal powder was manufactured using the water atomized metal powder manufacturing apparatus shown in FIG.

At%, 82.8% Fe-11% B-5% P-1.2% Cu Fe-B-P-Cu alloy (Fe _82.8 B ₁₁ P ₅ Cu _1.2 ) composition, at%, 84.8% Fe-10% B-4% P-1.2% Cu Fe-BP-Cu alloy (Fe _84.8 B ₁₀ P ₄ Cu _1.2 ) composition, and at%, 69.8% Fe-15% Co -10% B-4% P-1.2% Cu Fe-BP-Cu alloy (Fe _69.8 Co ₁₅ B ₁₀ P ₄ Cu _1.2 ) It was inevitable that impurities were included), and was melted at about 1650 ° C. in the melting furnace 2 to obtain about 50 kgf of molten metal 1 each. The obtained molten metal 1 was gradually cooled to 1600 ° C. in a melting furnace 2 and then poured into a molten metal holding container (tundish) 3. Note that the inside of the chamber 9 was previously opened with an inert gas valve 11 to create a nitrogen gas atmosphere.

  Before injecting the molten metal into the tundish 3, the high pressure pump 17 is operated to supply the cooling water from the cooling water tank 15 to the nozzle header 5 and the water 7 is injected from the water cooling nozzle 6. I left it. The position A where the primary cooling jet water (fluid) 7 is in contact with the molten metal flow 8 is set at a position 25 mm from the molten metal guide nozzle 4. The primary cooling water spray nozzles 6 were arranged on the lower surface of the nozzle header 5 on the circumference of the nozzle header 5 on the circumference toward the position A (30 ° each).

  Further, from the preset temperature of the molten metal flow at a predetermined position before dividing, as shown in FIG. 3, it is divided by the calculation through steps 1 to 3 in consideration of heat radiation, heat transfer, etc. The position B where the temperature (estimated) of the molten metal droplets in the range from the solidification start point to (solidification start point + 30 ° C.) was calculated. In addition, the value calculated | required with the thermodynamic calculation method was used for the solidification start point (solidification start temperature) of molten metal. Then, at the calculated position B, the secondary cooling means 2i capable of injecting the secondary cooling jet water 20 is selected, the secondary cooling control valve 2ia is opened, and the secondary cooling is performed from the water cooling nozzle of the secondary cooling means 2i. The jet water 20 was in the jet state. The secondary cooling water-cooled nozzles are full cone type spray nozzles with a spread angle of 30 °. Four nozzles are arranged on the circumference of each stage at 15 ° downwards (90 ° each), and 200 mm apart in the vertical direction. 5 stages of secondary cooling means were installed.

  The injection pressure of the primary cooling jet water is about 20MPa, the temperature is about 20 ℃, the total water volume is 1200L / min (100L / min per nozzle), the injection pressure of the secondary cooling jet water is about 30MPa, The temperature was 9 ° C, and the total amount of water per stage was 300 L / min (75 L / min per nozzle).

  Then, the molten metal 1 injected into the tundish 3 flows down from the molten metal guide nozzle 4 into the chamber 9 as a molten metal flow 8 and is divided by the primary cooling jet water 7 to obtain a large number of fine molten metal liquids. Drop 8a was produced. Further, secondary cooling of the droplet 8a was started by the secondary cooling jet water 20 at the position B described above to form water atomized metal powder, which was recovered from the recovery port 13.

  The temperature of the molten metal flow 8 was measured with a thermometer (fiber thermometer) 40 disposed at a preset position immediately before the position at which the molten metal flow 8 was divided. When the temperature of the molten metal flow 8 is monitored by the thermometer 40 described above and a difference from the calculated value is generated, the calculated value is corrected by changing the boundary conditions (mainly heat transfer coefficient) as appropriate. The secondary cooling start position B was switched from the plural stages of secondary cooling means to a suitable secondary cooling means to perform secondary cooling.

  The position B at which the secondary cooling is started is defined as a position where the temperature of the molten metal droplet 8a is (solidification start point + about 40 ° C.) and a position where the temperature is (solidification start point−about 20 ° C.). Next cooling was started and used as a comparative example.

  About the obtained metal powder, after removing dust other than metal powder, the average particle diameter was measured using the laser type particle size distribution analyzer.

  In addition, after removing dust other than the metal powder from the obtained metal powder, the halo peak from amorphous and the diffraction peak from crystal were measured by X-ray diffraction method, and the amorphization rate was measured by WPPD method. Was calculated. The case where the amorphization rate was 90% or more was evaluated as “◯”, and the others were evaluated as “×”.

  Further, the obtained metal powder was further subjected to heat treatment under the conditions shown in Table 1. After the heat treatment, the saturation magnetic flux density Bs was measured using a vibrating sample magnetometer VSM.

  The obtained results are shown in Table 1.

  In all of the inventive examples, the amorphization ratio is 90% or more, and the saturation magnetic flux density Bs after heat treatment is 1.7 T or more and has excellent magnetic characteristics. On the other hand, the comparative example out of the scope of the present invention has an amorphization rate of less than 90% and does not achieve the desired amorphization or shows only a low value of the saturation magnetic flux density Bs after the heat treatment. Absent.

1 Molten metal (molten metal)
2 Melting furnace 3 Tundish 4 Melt guide nozzle 5 Nozzle header 6 Water injection nozzle 7 Spray water 8 Molten metal flow 8a Molten metal droplet 9 Chamber 10 Hopper 11 Inert gas valve 13 Metal powder recovery valve 14 Water atomized metal powder production device 15 Cooling water tank 16 Chiller (low temperature cooling water production equipment)
17 High pressure pump (High pressure pump for primary cooling water)
18 Cooling water piping (primary cooling water piping)
20 Secondary cooling spray water 21, 22, ... 2i Secondary cooling means (water cooling nozzle)
21a, 22a, ... 2ia Secondary cooling control valve 37 Secondary cooling high pressure pump 38 Secondary cooling water piping (cooling water piping)
40 Thermometer (Thermometer for molten metal flow)

Claims (6)

In the method for producing water atomized metal powder, water is injected into the flowing molten metal stream, the molten metal stream is divided to form molten metal droplets, and further cooled to form water atomized metal powder.
At the position where the temperature of the molten metal droplet is an average temperature and is within the range of the solidification start point to (solidification start point + 30 ° C.) The manufacturing method of the water atomized metal powder characterized by starting the secondary cooling which consists of water cooling which injects secondary cooling injection water.   The water cooling for injecting the secondary cooling jet water is a secondary cooling means comprising water cooling nozzles arranged in a plurality of stages so as to be switchable in the dropping direction of the molten metal droplets. Selecting a secondary cooling means capable of jetting the secondary cooling jet water at a position where the temperature of the liquid droplets is an average temperature and a temperature not lower than the solidification start point (solidification start point + 30 ° C.) or lower. The method for producing a water atomized metal powder according to claim 1, wherein   The temperature of the molten metal droplet in the middle of dropping is a value estimated by measuring the temperature of the molten metal flow before the division and by heat transfer calculation based on the temperature of the molten metal flow before the division. The method for producing a water atomized metal powder according to claim 1 or 2, wherein:   The jet water that divides the molten metal flow uses water temperature: 50 ° C. or lower, jet pressure: water of 10 MPa or higher, and the secondary cooling jet water uses water temperature: 30 ° C. or lower, jet pressure: water of 10 MPa or higher. The method for producing a water atomized metal powder according to any one of claims 1 to 3, wherein:   The molten metal is a Fe-based soft magnetic alloy composition or a Fe-based soft magnetic alloy composition in which a part of Fe is replaced with Ni and / or Co, and is a Fe-based element that is the total amount of Fe or Fe, Ni, Co The method for producing a water atomized metal powder according to any one of claims 1 to 4, which has an alloy composition having a ratio of more than 82.5 at% and less than 86 at%. A water atomized metal powder produced by the water atomized metal powder produced by the method for producing a water atomized metal powder according to claim 5, further subjected to a heat treatment to be heated to a temperature within a range of 400 to 500 ° C. Manufacturing method .

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