JP2022093316A - Production method of molten raw material, and molten raw material - Google Patents

Abstract

To provide a production method of a molten raw material in which an alloy powder used for, for example, metal lamination molding, powder compacting, powder metallurgy and metal injection molding with respect to an alloy powder containing a high melting point element may be stably produced, and to provide the molten raw material.SOLUTION: A production method of a molten raw material comprises a pressure sintering step of sintering mixed powders comprising a plurality of kinds of raw material powders at a temperature of 2 MPa min/3 or more and a pressure of 5 MPa or more where the melting point of an element having the lowest melting point among the elements constituting the raw material powder is MPmin (°C). The raw material powder contains a high melting point metal element having a melting point of 1600°C or higher.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a dissolved raw material and a dissolved raw material, and more particularly to a method for producing a dissolved raw material containing a refractory element and a dissolved raw material.

Metal powder is an important basic material as a material for powder molding, powder metallurgy, metal injection molding (MIM), etc. in the field of raw materials. These raw material techniques using metal powder are suitably used for various industrial products because of their excellent strength and mass productivity. Further, in recent years, it has come to be used as a raw material for metal laminated molding (metal three-dimensional printing), and it has become possible to manufacture raw materials without a mold, and its importance is increasing.

Many alloys such as steel, aluminum alloys, copper alloys, nickel-based alloys, and titanium alloys have been used as metal powders used in such raw material technology. Furthermore, attempts have been made to dramatically improve heat resistance by adding refractory elements (metals) such as tungsten, molybdenum, and niobium.

Patent Document 1 discloses a method in which a raw material powder obtained by mixing titanium powder and aluminum powder is made into a rod-shaped raw material of a compact by cold molding, and the rod-shaped raw material is pulverized by a gas atomizing method.

JP-A-2002-241807

However, in the method disclosed in Patent Document 1, when a material having poor cold workability, for example, a refractory element (melting point metal) is contained, voids are formed inside the cold-formed molded body. Is likely to occur. Then, when the molded body is melted, the voids are the starting point to damage the molded body, and the air remaining in the voids makes the melting of the molded body unstable, so that the alloy powder can be stably produced. It was difficult to do.

From the above, an object of the present invention is to provide a melting raw material for an alloy powder containing a refractory element, for example, which can stably produce an alloy powder used for metal laminated molding, powder molding, powder metallurgy, metal injection molding and the like. The purpose is to provide the manufacturing method.

In the present invention, when a mixed powder composed of a plurality of kinds of raw material powders has a melting point of the element having the lowest melting point among the elements constituting the raw material powder as MP _min (° C.), the temperature is 2 MP _min / 3 or more. It is a method for producing a melting raw material, which comprises a pressure sintering step of sintering at a pressure of 5 MPa or more, and the raw material powder contains a high melting point metal element having a melting point of 1600 ° C. or more.

Further, it is preferable that at least one of the plurality of kinds of raw material powders contains two or more kinds of refractory metal elements.

Further, in the pressure sintering step, it is preferable to use a hot isotropic pressure sintering method.

The present invention is a melted raw material used for melting and spraying to obtain an alloy powder, which is a sintered body containing at least two kinds of refractory metal elements having a melting point of 1600 ° C. or higher and a porosity of less than 5%. It is a dissolution raw material characterized by being present.

According to the present invention, for an alloy powder containing a refractory element, for example, a method for producing a melting raw material capable of stably producing an alloy powder used for metal laminated molding, powder molding, powder metallurgy, metal injection molding, etc., and melting. Raw materials can be provided.

It is a process drawing which shows an example of the manufacturing method of the metal powder which concerns on this invention. It is a schematic diagram which shows one Embodiment of the dissolution / spraying process about the manufacturing method of the metal powder which concerns on this invention. It is a schematic diagram which shows the other embodiment of the melting / spraying process about the manufacturing method of the metal powder which concerns on this invention. It is sectional drawing which shows the structure of the laminated modeling apparatus of the selective laser melting method, and the example of the laminated modeling method. It is sectional drawing which shows the structure of the laminated modeling apparatus of the laser beam powder overlay method, and the example of the laminated modeling method.

First, the present inventors have conducted extensive research on a method for producing a metal powder containing a large amount of high melting point elements, which is difficult to uniformly dissolve with existing melting (melting) equipment. As a result, a plurality of raw material powders containing a metal element having a melting point of 1600 ° C. or higher are uniformly mixed so as to have a desired composition, and the metal powder to be produced is sintered at a predetermined temperature and pressure. A sintered body (sometimes called a raw material bar) having substantially the same composition is manufactured. Then, they have found that an alloy powder (pre-alloy powder) having a desired composition can be stably obtained by powdering the melt obtained by locally dissolving the sintered body.

<Manufacturing method of dissolved raw materials>
Hereinafter, embodiments of the manufacturing method of the present invention will be described with reference to FIG. FIG. 1 is a process diagram showing a method for producing a dissolution raw material according to an embodiment of the present invention and a suitable production method for obtaining an alloy powder using the dissolution raw material.

[Pressure sintering step (S101)]
First, the raw material powder will be described. A raw material powder containing a refractory metal is mixed according to the composition of a desired alloy powder to obtain a mixed powder. At this time, one raw material powder contains a metal element having a melting point of 1600 ° C. or higher (high melting point metal element), and by mixing two or more such raw material powders, at least two or more kinds of high melting points are obtained. Obtain a mixed powder containing a metallic element. Examples of the refractory metal element include tungsten (W), renium (Re), osmium (Os), tantalum (Ta), molybdenum (Mo), niobium (Nb), iridium (Ir), ruthenium (Ru), and hafnium. (Hf), technetium (Tc), rhodium (Rh), vanadium (V), chromium (Cr), zirconium (Zr), thorium (Th), titanium (Ti) and the like. The mixing method is not particularly limited, but for example, various powder mixers such as a ball mill can be used. As a method for producing the raw material powder, a chemical reduction method, a pulverization method, or the like is selected depending on the raw material. Further, the raw material powder may include the powder produced by the atomizing method.

Further, as the raw material powder, powders containing a high melting point metal element may be mixed in advance, and a raw material powder containing two or more kinds of high melting point metal elements may be used in advance. The mixing method is the same as described above, for example, a ball mill. It is preferable to mix uniformly by using various powder mixers such as.

The average particle size of the raw material powder is preferably set to 1 μm or more and 1 mm or less. When the average particle size is 1 μm or more, the fluidity of the powder can be ensured and the powder can be suppressed from flying up. By setting the average particle size to 1 mm or less, it is possible to suppress the remaining voids between the powders in the pressure sintering step described later.

Next, a method for producing a dissolved raw material by pressure sintering the mixed powder will be described.
The dissolution raw material referred to in the present specification is for dissolving and spraying to obtain an alloy powder, and by mixing the raw material powder, a mixed powder containing at least two kinds of refractory metal elements is pressure sintered. It is a thing. Therefore, although it refers to a sintered body, it can also be rephrased as a melting raw material, a raw material bar, and a consumable electrode. The shape of the sintered body is not particularly limited, but a rod shape is preferable because it is easy to handle in the melting / spraying step. Hereinafter, the pressure sintering step (S101) to the melting / spraying step (S103) will be described with the shape of the sintered body as a bar material and referred to as a raw material bar material.

In the pressure sintering step, when the melting point of the element having the lowest melting point among the elements constituting the raw material powder is set to MP _min (° C), the mixed powder is mixed at a temperature of 2 MP _min / 3 or more and a pressure of 5 MPa or more. Is a process of obtaining a raw material bar by pressure sintering. The porosity of the sintered body is set to less than 5% under the conditions that the temperature is 2/3 or more of the melting point MP _min of the element having the lowest melting point among the elements constituting the raw material powder and the pressure is 5 MPa or more. be able to. This is suitable because it can prevent the sintered body from being damaged and air from being mixed in the melting / spraying process in which the sintered body is melted and powdered. A more preferable temperature is 5/7 or more of MP _min , and a more preferable temperature is 3/4 or more. Further, a more preferable pressure is 20 MPa or more, and a more preferable pressure is 40 MPa or more. Further, the upper limit of the temperature is not particularly limited, but it is preferable that the temperature is set to less than MP _min because the reaction of the liquid phase between the raw material powders can be less likely to occur and the uniformity of the composition can be easily ensured. The upper limit of the pressure depends on the strength of the furnace body and is about 300 MPa.

As a method for producing such a raw material bar by pressure sintering, a powder compaction method, a uniaxial pressure sintering method (hot press, discharge plasma sintering (SPS: Spark Plasma Sintering), hot or the like, etc. A method pressure sintering method (HIP: Hot Isostatic Press) can be used, but from the viewpoint of sintering density and the like, a uniaxial pressure sintering method capable of uniformly compressing or hot isotropic pressure firing can be used. It is preferable to use the method.

Among the pressure sintering methods, it is particularly preferable to use a uniaxial pressure sintering method (hot press, SPS method) or a hot isotropic pressure sintering method (HIP method) capable of uniformly compressing. These pressure sintering methods are more preferable because they can more effectively reduce the voids between the raw material powders and obtain a raw material rod having a porosity of less than 2%. Further, the hot isotropic pressure sintering method capable of isotropically pressurizing is more preferable because the material can be uniformly shrunk and solidified. If the sintered body is produced through such a pressure sintering step, the occurrence of defects in the melting / spraying step (S103) can be further suppressed.
The porosity referred to in the present specification is the ratio of the area occupied by the void to the observed region (visual field area). For example, an arbitrary part of the obtained dissolved raw material (sample) is cut and the cut surface is polished. The surface of the polished sample is observed at a magnification of 200 to 1000 times using an optical microscope or the like, and the observed area is acquired as image data such as a photograph. Since the void portion is shown in black on the image, the area occupied by the black portion, that is, the area occupied by the void may be calculated by binarizing the image.

The case where the HIP method is used in the pressure sintering step will be described more specifically.
First, the raw material powder is sealed in a capsule (container) that matches the size of the raw material bar, degassed, and sealed. The size of the capsule is appropriately set in consideration of the shape shrinkage after the HIP treatment. After that, it is loaded into the HIP device, and when the above-mentioned set temperature and set pressure, that is, the melting point of the element having the lowest melting point is set to MP _min (° C.), the HIP treatment is performed by a temperature of 2 MP _min / 3 or more and a pressure of 5 MPa or more. I do. The raw material bar is obtained by removing the capsules after the treatment. It is also possible to prepare a raw material rod material temporarily molded by another method instead of the capsule and to produce the raw material rod material by a capsule-free method (open HIP method) in which a HIP treatment is performed.

The pressure sintering conditions are as described above. For example, a capsule containing a refractory material as a raw material powder is degassed to 0.01 MPa or less and sealed. Then, the capsule is placed in a HIP facility and held under pressure at a temperature of 100 ° C. to 2000 ° C. and a pressure of 10 MPa to 200 MPa for about 1 hour to 10 hours to solidify the raw material powder in the capsule and solidify the raw material stick. Make the material.

The raw material bar is set to have a diameter of 10 mm or more and 500 mm or less and a length of 10 mm or more and 3000 mm or less, for example, depending on the equipment used in the melting / spraying step. The voids between the raw material powders defined by the evaluation of the void area by observing the cross section of the obtained raw material rod can be less than 5%, more preferably less than 2%. Such a raw material bar is suitable because it can prevent damage to the bar and mixing of air in the process of dissolving and spraying the raw material bar. As described above, the raw material bar obtained in this step has excellent mechanical strength.

[Dissolution / spraying step (S103)]
Next, a suitable melting / spraying step for obtaining an alloy powder using a raw material bar will be described with reference to FIGS. 2 and 3.
FIG. 2 is a diagram showing a suitable form of the melting / spraying step of the method for producing an alloy powder, and shows a direct melting gas atomizing method. FIG. 3 is a diagram showing another form of the melting / spraying process, and shows a plasma arc heating method. The direct dissolution gas atomization method and the plasma arc heating method described below are suitable because the melt does not come into contact with the crucible or the like and the cleanliness of the melt can be ensured.
First, an embodiment in the case of directly applying the dissolved gas atomizing method will be described with reference to FIG. 2.

First, the raw material bar 11 is placed in the induction heating device 13 of the powder manufacturing device 12. The raw material bar may be fixed to the induction heating device with its central axis aligned with each other, or may be rotated around the central axis in order to equalize the heat of the raw material bar 11.

After that, the atmosphere in the powder manufacturing apparatus 12 is changed to a vacuum-like reduced pressure atmosphere or an inert gas atmosphere, and one end of the raw material bar 11 is melted by the induction heating apparatus 13. The melt 14 is formed from one end of the melted raw material bar 11, and is dropped downward by gravity. At this time, the melt 14 is uniformly agitated by the flow field generated by the induction heating. Then, the melt 14 is sprayed with a high-pressure gas 16 such as argon, nitrogen, and air ejected from the gas nozzle 15 to the melt 14 that has fallen downward, and the melt 14 is cooled and solidified during scattering to solidify the spray powder 17. To get.

More specifically, the alloy powder 17 can be produced by directly applying the dissolved gas atomizing method to the obtained raw material bar 11. The raw material bar 11 is directly installed in the dissolved gas atomizing device, and the atmosphere is set to a reduced pressure atmosphere of 0.01 MPa or less. Then, the end portion of the raw material rod 11 is melted by an induction heating device arranged near the end portion of the raw material rod 11 to obtain a melt, and the melt falling downward is charged with 2 to 20 MPa and 100 to 1500 L / min. The sprayed powder can be obtained by spraying the melt with pure argon gas and cooling and solidifying during the scattering.

At this time, the arrangement of the gas nozzles, the gas flow rate, the flow velocity, the pressure, and the like may be appropriately adjusted so that the particle size distribution of the spray powder 17 becomes a desired value. As described above, in the present embodiment, the spray powder 17 can be obtained without the melt 14 of the raw material bar 11 touching the crucible or the like, and there is an advantage that the cleanliness of the spray powder 17 can be ensured. The high-pressure gas 16 is not particularly limited, and an inert gas such as argon gas or nitrogen gas may be appropriately selected in consideration of the reactivity with the high-temperature melt.

In the melting / spraying step, it is preferable to use a high frequency induction heating method or a plasma arc heating method as a method for locally melting (melting) one end of the raw material bar 11. As a result, it is possible to melt the other end side of the raw material rod 11 in a non-contact manner while holding one end, and it is possible to supply the melt to a crucible or the like without contacting it, thereby suppressing the mixing of impurities. can do.

Further, the melting rod 11 may be used in the plasma arc heating method. In the plasma arc heating method, the melting rod is melted by the heat of the plasma arc, but it is melted by exposing the obtained melt to a high-pressure gas or by using a rotary electrode method in which the raw material rod is melted while rotating. The liquid can be scattered by centrifugal force, or ultrasonic waves can be applied to the melt. As a specific example, the rotary electrode method will be described as an example. In the rotary electrode method, the raw material rod 11 is melted while rotating by plasma arc heat, and the obtained melt is scattered by centrifugal force and solidified during the scattering to obtain a spray powder. These can be selected together with the dissolving means, and all of them can be solidified without contacting the crucible or the like with the melt, so that the mixing of impurities can be suppressed. Here, the centrifugal force and slight vibration applied to the melt may be appropriately set according to the particle size, circularity, etc. of the spray powder by arranging a rotation mechanism or a vibration mechanism on the raw material bar. do it.

More specifically, as shown in FIG. 3, the raw material bar 21 is fixed to the electrode rotation mechanism 23 of the powder manufacturing apparatus 22 so as to be able to rotate about the axis. After that, the atmosphere is set to a vacuum atmosphere or an inert gas atmosphere, and the raw material bar 21 is rotated at a high speed of 10,000 rpm or more around the central axis. This rotation speed is used to control the particle size of the spray powder 26. In a state where the raw material bar 21 is rotated, one end of the raw material bar 21 is melted by the plasma heating device 24, and the generated melt 25 is immediately scattered by the centrifugal force applied by the rotation. Then, the spray powder 26 is obtained by cooling and coagulating the melt during scattering.

The raw material bar is installed in the electrode rotation mechanism 23, and the atmosphere is set to a reduced pressure atmosphere of 0.01 MPa or less. Then, the raw material bar 21 is rotated around the long axis of the bar at a rotation speed of, for example, 10000 rpm. A plasma heating device arranged near the end of the raw material bar 21 melts the end of the rotating raw material bar 21 to obtain a melt, which is then scattered laterally by the centrifugal force generated by the rotation of the raw material bar 21. .. Then, the spray powder 26 is obtained by cooling and solidifying the melt during scattering.

In the above dissolution / spraying step, the spray powder can be obtained directly from the melt of the sintered body (raw material bar), and there is an advantage that the cleanliness of the spray powder can be ensured. Further, since the spray powder can be formed without interaction with the high-pressure gas, it can be a spray powder having a higher sphericity than the alloy powder obtained by the gas atomizing method.

As described above, in the embodiment of the alloy powder manufacturing method as described above, since the alloy powder can be manufactured without using a crucible, the alloy containing the melted refractory metal does not remain in the crucible, and the undissolved residue or the like. It is possible to suppress the occurrence of compositional non-uniformity due to the reaction with the crucible, and it is possible to obtain a spray powder (sometimes referred to as an alloy powder) having a desired composition.

[Classification step (S105)]
It is preferable to add the classification step (S105) after passing through the above steps (S101 to S103). It is preferable to adjust the particle size distribution of the spray powder (alloy powder) obtained in the dissolution / spray step (S103) by a method such as a sieving classification method or a swirling airflow classification method. The average particle size of the specific alloy powder is preferably 10 μm or more and 200 μm or less from the viewpoint of handleability and filling property. If the average particle size is less than 10 μm, the alloy powder tends to fly up, which may cause a decrease in the shape accuracy of the laminated model. On the other hand, when the average particle size exceeds 200 μm, not only the surface roughness of the laminated model increases, but also the melting of the alloy powder 20 having a particularly high melting point becomes insufficient. Further, the suitable average particle size differs depending on the production method used in this. For example, for example, the metal laminating method is more preferably 10 μm or more and 50 μm or less in the selective laser melting (SLM) method, and 45 μm or more and 105 μm or less in the electron beam laminating method (EBM).

Further, in the laser beam powder overlay (Laser Metal Deposition: LMD) method, it is preferable that the thickness is 50 μm or more and 200 μm or less.

Further, according to the method for producing an alloy powder using the melting raw material of the present embodiment, an alloy powder of a high entropy alloy (HEA) composed of Nb, Mo, Ta, W and the like containing many kinds of refractory elements and the like can be produced. It is also possible to do.

As described above, according to one embodiment of the above-mentioned method for producing a melting raw material, an alloy powder of HEA containing a refractory metal can be produced. In addition, there is also the effect of suppressing segregation of relatively low melting point Nb and Mo and relatively high melting point Ta and W, which was a problem when mixing high melting point pure metal powder and melting by the SLM method. It can be expected, and the effect of suppressing the concentration fluctuation of the laminated model obtained by laminating the alloy powder can also be expected.

<Alloy powder>
By the above-described embodiment of the suitable method for producing an alloy powder, it is possible to obtain an alloy powder containing two or more kinds of high melting point elements, specifically, high melting point metal elements having a melting point of 1600 ° C. or higher. Further, it is also possible to obtain an alloy powder having a circularity of 0.5 or more, preferably 0.7 or more, and an average particle size of 10 μm or more and less than 200 μm. The composition of the alloy powder can be evaluated by inductively coupled plasma emission spectroscopy.

Using the alloy powder described above, it is also possible to perform additive manufacturing by additive manufacturing by the SLM method by the powder additive manufacturing device as shown in FIG. As the modeling conditions, for example, a laser output: 100 W to 300 W, a laser scanning speed: 50 to 300 mm / sec, and a scanning interval: 0.01 to 0.10 mm can be applied, but the modeling conditions are not particularly limited.

Further, for example, a modeling member by the LMD method can be laminated and modeled on the obtained alloy powder by using a powder layered manufacturing apparatus as shown in FIG. As modeling conditions, for example, laser output: 0.6 to 2.4 kW, scanning speed: 100 to 1500 mm / min, scanning interval: 0.5 to 3.0 mm, powder supply amount: 4 to 14 g / min should be applied. However, there is no particular limitation.

[Use / Manufacturing]
The alloy powder produced by the above-mentioned suitable production method is particularly effective for alloys containing refractory metal as a main component, and is suitable for metal laminated molding, powder molding, powder metallurgy, metal injection molding and the like. It can be used, but its use and product are not particularly limited.

As an example of the use of the molded product and the molded product using the alloy powder of the present invention, a mold, an electrode component, a heating heat source, a heat treatment furnace and a structure in a reaction furnace, an X-ray and a particle beam filter, which are used in a high temperature environment, are used. It is suitable for application to machining tools and the like. The term "manufactured product" as used herein is a general term for these machines, devices, members, molds, parts, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to these examples.

[Experiment 1]
(Preparation of mixed powder of A1 and A2)
A plurality of raw material powders were mixed at the mass ratio shown in Table 1 to prepare a mixed powder of A1 and A2. The raw material powders were all pure alloy powders obtained by the chemical reduction method, and as shown in Table 1, all of them contained 10% by mass or more of powders of metal elements having a melting point of 1600 ° C. or higher. By mixing with a V mixer for 30 minutes or more, a plurality of raw material powders having different specific densities in each raw material powder were uniformly mixed.

[Experiment 2]
<Manufacturing of raw material bars B1 and B2>
10 kg each of the mixed powders A1 and A2 prepared in Experiment 1 was encapsulated in a capsule (diameter 120 mm, height 600 mm, manufactured by SUS304), degassed to 0.01 MPa or less, and sealed. Then, it was placed in a HIP facility and kept at 1250 ° C. under a pressurized atmosphere of 110 MPa for 5 hours to solidify each raw material powder in a capsule. As a result, raw material rods B1 and B2 having a diameter of 100 mm and a length of 500 mm corresponding to A1 and A2 were obtained.

(Example)
As a result of evaluation of the void area by observing the cross section of the obtained raw material rod, the raw material rod B1 had a porosity of 4% and the raw material rod B2 had a porosity of 1%. Although all of them use powder having a high melting point composition, they could be solidified into a bar having a sufficiently low porosity by HIP treatment under high temperature and high pressure.

(Comparative Example 1)
Based on A1, we tried to prepare a raw material bar by cold pressing (room temperature (22 ° C), 100 MPa, 10 minutes), but the pressed raw material did not bond with each other and did not solidify. I couldn't get it.

(Comparative Example 2)
Hot press (100 MPa, 10 minutes) at 300 ° C, which is less than 2/3 ° C of the melting point of Zr (1855 ° C), which is an element having the lowest melting point among the elements constituting the raw material powder based on A1. However, it was not possible to obtain a dense rod because the porosity was high and it did not solidify. As a result of evaluation of the void area by observing the cross section of this raw material bar, the porosity was 28%.

The above-described embodiments and examples have been described for the purpose of assisting the understanding of the present invention, and the present invention is not limited to the specific configuration described. For example, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. That is, the present invention can delete a part of the configurations of the embodiments and examples of the present specification, replace them with other configurations, or add other configurations. By adjusting such an embodiment, the alloy powder disclosed in the present invention can be applied to the production of high melting point metal parts used in high temperature parts, plant equipment, mold members and the like.

11: Raw material bar 12: Powder production device 13: Induction heating device 14: Melt 15: Gas nozzle 16: High pressure gas 17: Spray powder 22: Powder production device 23: Electrode rotation mechanism 24: Plasma heating device 25: Melt 26 : Spray powder 100: SLM powder laminated molding device 101: Modeling member 102: Stage 103: Base plate 104: Powder supply container 105: Alloy powder 106: Ricator 107: Powder bed (layered powder)
108: Laser oscillator 109: Laser beam 110: Galvanometer mirror 111: Container for collecting unmelted powder 112: Solidification layer 200 in 2D slice shape: Powder layered manufacturing device 201: Laser head 202: Modeling base material 203: Vise (fixed cure) Ingredients)
204: Table 205: Laser oscillator 206: Powder feeder 210: Device outer wall 211: Full door 212: Operation panel 220: Nozzle 221: Powder 222: Shield gas 223: Modeled body

Claims (4)

When the melting point of the element having the lowest melting point among the elements constituting the raw material powder is MP _min (° C.), the mixed powder composed of a plurality of kinds of raw material powders has a temperature of 2 MP _min / 3 or more and 5 MPa or more. A method for producing a dissolved raw material, which comprises a pressure sintering step of sintering at the pressure of the above, wherein the raw material powder contains a high melting point metal element having a melting point of 1600 ° C. or higher. The method for producing a dissolved raw material according to claim 1, wherein at least one of the plurality of kinds of raw material powders contains two or more kinds of refractory metal elements. The method for producing a dissolution raw material according to claim 1 or 2, wherein a hot isotropic pressure sintering method is used in the pressure sintering step. It is a melting raw material used to melt and spray to obtain alloy powder.
Contains at least two types of refractory metal elements with a melting point of 1600 ° C or higher.
A dissolution raw material characterized by being a sintered body having a porosity of less than 5%.

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