JP6393885B2 - Method for producing alloy powder - Google Patents

Description

  The present invention relates to a method for producing an alloy powder.

  Alloy materials are used in various applications including structural members that form the framework of structures and equipment, various mechanical members, etc., and for applications in harsh environments where it is difficult to use steel and aluminum materials. Often used. For example, nickel-based alloys, cobalt-based alloys, and the like have been developed that can be applied to turbine members and the like provided in aircrafts, generators, and the like and can be applied to an ultra-high heat environment of 1000 ° C. or higher. In addition, high alloy steels and the like that can exhibit high corrosion resistance and wear resistance even under such an ultra-high heat environment have been developed.

  In recent years, multi-element alloys called high-entropy alloys (HEAs) have attracted attention as a kind of alloy material. High entropy alloys are generally composed of a plurality of elements of about five or more types and contain each element in an equiatomic ratio or an atomic ratio in the vicinity thereof. Since it has the characteristics of slow atomic diffusion and is excellent in heat resistance, high temperature strength, corrosion resistance, etc., it is expected to be applied to applications in harsh environments.

  As a technique applying a high entropy alloy, for example, Patent Document 1 discloses a method of manufacturing a cemented carbide composite material, in which at least one ceramic phase powder and a multi-element high entropy alloy powder are mixed to form a mixture. A step of compacting the mixture, and a step of sintering the mixture to form a cemented carbide composite material, wherein the multi-element high-entropy alloy powder is composed of 5 to 11 main elements, Discloses a production method comprising 5 to 35 mol% of the multi-element high-entropy alloy powder.

  Non-Patent Document 1 discloses that a high-entropy alloy having an equiatomic ratio of Al, Co, Cr, Fe, and Ni analyzed the dimensional effect on the microstructure and mechanical properties.

JP 2009-074173 A

F. J. Wang, Y. Zhang, G. L. Chen, H. A. Davies, “Cooling rate and size effect on the microstructure and mechanical properties of AlCoCrFeNi high entropy alloy”, Journal of Engineering Material Technology, 131 (3), 034501-1 (2009).

  In order to manufacture high-entropy alloys as structural materials such as structural members and mechanism members, and to produce structures that take advantage of these properties, the main constituent elements of the high-entropy alloys are dissolved in an equiatomic ratio. At the same time, it is desired to form a solid solution phase so that the uniformity of the elemental composition distribution is high over the entire structure having a wide variety of shape dimensions.

However, in the conventional high-entropy alloy manufacturing method exemplified in the mechanical alloying method disclosed in Patent Document 1 and the arc melting method disclosed in Non-Patent Document 1, the element composition distribution, the melting rate, and the cooling rate It was difficult to form a solidified structure having a uniform elemental composition distribution, and it was difficult to increase the size of a solid solution phase in which each element was substantially dissolved in an equiatomic ratio. . For example, the alloy material disclosed in Non-Patent Document 1 is only a small piece of diameter 10 mm × height 70 mm (volume 5495 mm ³ ) even for the largest prototype material, and it is difficult to apply it as a material for a structure.

  In particular, when a relatively large structure is to be cast, a process of melting a large amount of metal or solidifying the molten metal is required. Therefore, unevenness in element composition distribution, melting rate, cooling rate, etc. There is a problem that the influence is strongly expressed and it is difficult to form a solid solution phase of the high entropy alloy. High-entropy alloys have good high-temperature strength and corrosion resistance, but have a slow atomic diffusion rate, so that uniformity of elemental composition and mechanical strength is ensured by heat treatment after solidification. Is difficult. In addition, since it is difficult to process, it is difficult to obtain a structure of arbitrary shape by cutting after solidification, etc., and a high entropy alloy structure with high uniformity of elemental composition and mechanical strength distribution can be obtained. There is a difficult current situation.

  Therefore, an object of the present invention is to provide an alloy structure having an arbitrary shape and dimension having high uniformity in distribution of elemental composition and mechanical strength and having good high-temperature strength and corrosion resistance.

  In order to solve the above problems, the present invention employs, for example, the configurations described in the claims.

  According to the present invention, it is possible to provide an alloy structure having an arbitrary shape and dimension having high uniformity in distribution of elemental composition and mechanical strength and having good high-temperature strength and corrosion resistance.

It is a conceptual diagram which shows an example of the process of the manufacturing method of the alloy material which concerns on this embodiment. It is sectional drawing which showed the outline of the metal structure which an alloy structure has. (A) is sectional drawing of the alloy structure which concerns on this embodiment, (b) is an expanded sectional view of the A section in (a), (c) is the outline of the metal structure which the alloy material which concerns on a comparative example has It is sectional drawing which showed. It is a schematic flowchart which shows an example of the manufacturing method of the alloy powder used as a raw material of an alloy structure. It is the figure which showed an example of the progress of the density | concentration change of the impurity element in the alloy powder prepared using the vacuum carbon deoxidation method. It is a figure which shows the shape dimension of the alloy structure which concerns on Example 3. FIG. 6 is a compression true stress-compression true strain diagram in an alloy structure according to Example 3. FIG. It is a figure which shows the test temperature dependence of the tensile strength in the alloy structure which concerns on Example 4. FIG. It is a figure which shows the range of the main component elements which can form a solid solution phase in an alloy structure. It is a figure which shows the shape dimension of the alloy structure which concerns on Example 6. FIG.

  Hereinafter, an alloy structure according to an embodiment of the present invention will be described. In addition, about the structure which is common in each figure, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The alloy structure according to the present embodiment has a high content mainly composed of iron (Fe) and at least four or more other elements that solidify with Fe (hereinafter sometimes referred to as non-Fe main component elements). It is a metal shaped article made of an entropy alloy and shaped to a desired shape by additive manufacturing. This alloy structure contains a non-Fe main component element and an Fe element at an atomic concentration in the range of 5 at% or more and 30 at% or less for each element, and at least four kinds of these elements are contained. It has an elemental composition with a substantially equiatomic ratio. The non-Fe main component element and the Fe atom form a solid solution phase in which these plural types of elements are solidly dissolved. Therefore, this alloy structure has high heat resistance, high temperature strength, wear resistance, and corrosion resistance as general properties as a high entropy alloy. Further, as will be described later, it has a specific solidified structure formed by additive manufacturing, and has a feature of high uniformity of elemental composition and mechanical strength distribution.

  The alloy structure according to the present embodiment is substantially composed of a collection of columnar crystals at a normal temperature and a normal pressure. The proportion of the columnar crystals is at least 50% or more in the area occupied by the solidified structure in an arbitrary cross section, and is 90% or more or 95% or more depending on the formation conditions of the solidified structure in the manufacturing method described later. It is also possible. The average crystal grain size of the columnar crystals is 100 μm or less, and can be further refined to 10 μm or less. The average crystal grain size can be determined according to the method defined in JIS G 0551 (2013).

  The main crystal of the alloy material structure has a face-centered cubic lattice or a body-centered cubic lattice crystal structure at normal temperature and normal pressure. By selectively designing the composition, the proportion of the crystal structure of the face-centered cubic lattice can be 90% or more, or 95% or more in terms of the occupied area ratio in an arbitrary cross section of the solidified structure. In addition, the proportion of the crystal structure of the body-centered cubic lattice can be 90% or more, or 95% or more in terms of the occupied area ratio in an arbitrary cross section of the solidified structure.

  The non-Fe main component element is an element of atomic number 13 to atomic number 79 included in groups 3 to 16 (groups 3A to 6B) of the periodic table, and has an atomic radius with respect to Fe atoms Is selected from elements other than Fe having a ratio of 0.83 to 1.17. As such non-Fe main component elements, specifically, Al, Si, P, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Nb, Mo, Examples include Tc, Ru, Rh, Pd, Ag, Sn, Sb, Te, Ta, W, Re, Os, Ir, Pt, and Au. By setting the alloy structure to such an elemental composition, an atomic volume effect is exerted, and a stable solid solution phase exhibiting an action as a high entropy alloy can be formed.

  As the non-Fe main component element, it is more preferable to contain an element having an atomic radius ratio of 0.92 to 1.08, more preferably containing only such an element together with Fe. Specific examples of the non-Fe main component element which is a main component element together with Fe include Si, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Tc, Ru, Rh, Re, Os, Ir are mentioned. Among these, more preferable non-Fe main component elements are V, Cr, Mn, Co, Ni, Cu, Ge, and Mo, and it is particularly preferable to contain Co, Cr, and Ni.

  The elemental composition of the alloy structure is specifically CoCrFeNiAl, CoCrFeNiCu, CoCrFeNiCuAl, CoCrFeNiCuAlSi, MnCrFeNiCu, CoCrFeNiMnGe, CoCrFeNiMn, CoCrFeNiMnCu, TiCoCrFeNiCuAlV, TiCoCrFeNiAl, AlTiCoCrFeNiCuVMn, TiCrCrNi. CoCrFeNiCuAl, MnCrFeNiAl, MoCrFeNiCu, TiCoCrFeNi, TiCoCrFeNiMo, CoCrFeNiCuAlV MnCrFeNiCu, it TiCoCrFeNi, TiCoCrFeNiAl, CoCrFeNiMo, CoCrFeNiAlMo, TiCoCrFeNiCu, CoCrFeNiCuAlMn, TiCoCrFeNiMo, CoCrFeNiCuAlV, TiCoCrFeNiCuVMn, AlTiCoCrFeNiCuVMn, CoCrFeNiCuAlMn, CoCrFeNiAlMo, CoCrFeNiCuAlMo, be illustrated TiCoCrFeNiCu like. In these elemental compositions, the atomic concentration (molar ratio) of each element is such that the atomic concentration is in the range of 5 at% or more and 30 at% or less, and at least four elements are substantially in the atomic ratio. As long as and are satisfied, various values can be taken. However, when Ti is contained as a component element, Ti is not a component having the maximum atomic concentration among the component elements, and preferably the atomic concentration per alloy structure is 5 at% or more and less than 10 at%.

  The alloy structure is allowed to contain elements of other inevitable impurities in addition to the non-Fe main component element and Fe. Examples of unavoidable impurity elements include P, Si, S, Sn, Sb, As, Mn, O, and N. However, for P, it is preferably 0.005 wt% or less, more preferably 0.002 wt% or less, for Si, preferably 0.040 wt% or less, more preferably 0.010 wt% or less, and for S, Preferably it is 0.002 wt% or less, more preferably 0.001 wt% or less, Sn is preferably 0.005 wt% or less, more preferably 0.002 wt% or less, and Sb is preferably 0.002 wt%. Or less, more preferably 0.001 wt% or less, As is preferably 0.005 wt% or less, more preferably 0.001 wt% or less, and Mn is preferably 0.050 wt% or less, more preferably 0 Limited to 020 wt% or less. Further, O is preferably 0.001 wt% or less (10 ppm or less), more preferably 0.0003 wt% or less (3 ppm or less), and N is preferably 0.002 wt% or less (20 ppm or less), more preferably Is limited to 0.001 wt% or less (10 ppm or less). Thus, by limiting the concentration of inevitable impurities contained in the alloy structure, the uniformity of the distribution of elemental composition and mechanical strength can be made higher regardless of the shape and size of the structure. In addition, when the P, Si, Sn, Sb, As, or Mn element is contained in the alloy structure as a non-Fe main component, the element concentration need not be limited in this way.

  The alloy structure contains a non-Fe main component element and at least four elements of Fe in an atomic concentration range of 5 at% to 23.75 at% in a substantially equiatomic ratio. At this time, other elements are contained in the atomic concentration range of 5 at% or more and 30 at% or less, and the remainder is composed of inevitable impurities. When at least four kinds of elements are contained in an equiatomic ratio in this way, the mixed entropy term of free energy increases, so that the solid solution phase is stabilized. In the present specification, “substantially equiatomic ratio” means that the difference in atomic concentration is in the range of less than 3 at%.

  The element type and atomic ratio composing the alloy structure can be selected and designed by, for example, determining the formation enthalpy, entropy or Gibbs energy by thermodynamic calculation. For example, the ratio of atomic concentrations of at least four kinds of elements contained in an equiatomic ratio and other elements can be appropriately changed within the above-mentioned atomic concentration range. By changing the ratio of the atomic concentrations of these main component elements, the crystal structure of the alloy structure can be changed, and the mechanical strength, ductility, hardness, density, and the like can be adjusted. As the thermodynamic calculation, a first-principles calculation method, a Calphad (Calculation of phase diagrams) method, a molecular dynamics method, a phase-field method, a finite element method, or the like can be used in appropriate combination.

  The alloy structure contains, for example, Al in an atomic concentration range of 5 at% to 30 at%, and substantially contains Co, Cr, Fe, and Ni in an atomic concentration range of 15 at% to 23.75 at%. It can be set as the element composition contained by an equiatomic ratio. When the atomic concentration of Al contained in the alloy structure is lowered in the range of 5 at% or more and 30 at% or less, the main phase of the alloy structure can be constituted by a crystal structure of a face-centered cubic lattice. On the other hand, when the atomic concentration of Al is increased in the range of 5 at% or more and 30 at% or less, the main phase of the alloy structure can be constituted by a body-centered cubic crystal structure. Further, if the atomic concentration of Al contained in the alloy structure is 5 at% or more, the mechanical strength of the alloy structure is less likely to be excessively reduced. On the other hand, the atomic concentration of Al contained in the alloy structure is 30 at%. % Or less, the main phase of the alloy structure is less likely to be an Al-based intermetallic compound, so that the ductility of the alloy material is less likely to deteriorate excessively.

  Similarly, Co is contained at a substantially equal atomic ratio within the atomic concentration range of 5 at% to 30 at%, Al, Cr, Fe and Ni at 15 at% to 23.75 at%, or Cr at 5 at%. 30 at% or less, Al, Co, Fe and Ni are contained in a substantially equiatomic ratio within the atomic concentration range of 15 at% or more and 23.75 at%, or Fe is 5 at% or more and 30 at% or less, Al, Co , Cr and Ni are contained in a substantially equiatomic ratio within the atomic concentration range of 15 at% to 23.75 at%, Ni is 5 at% to 30 at%, Al, Co, Cr and Fe are at least 15 at% It is also possible to contain it at a substantially equiatomic ratio within the atomic concentration range of 23.75 at% or less.

  Next, a method for manufacturing an alloy structure according to this embodiment will be described.

  The alloy structure according to the present embodiment can be manufactured by powder additive manufacturing using alloy powder. This is a method for producing an alloy structure as a three-dimensional object having a desired shape and size by melting and solidifying an alloy powder to form a solidified structure and arranging a number of solidified structures while being integrated with the surroundings. . The manufacturing method of the alloy structure which concerns on this embodiment comprises the powder preparation process which prepares the alloy powder used for additive manufacturing, and the additive manufacturing process which models an alloy structure using the prepared alloy powder.

  In the powder preparation step, an alloy powder is prepared that contains the same main component elements and additive elements as the alloy structure to be manufactured and has an elemental composition in which the main component elements have a substantially equiatomic ratio. The alloy powder is preferably a particle aggregate in which each powder particle has substantially the same elemental composition as the alloy structure to be manufactured. In addition, when heating the alloy powder in the solidified layer forming process, some of the alloy components may volatilize and be lost, so the atomic concentration range is set to a high range in consideration of such volatilization of the composition change. Also good.

  As a method for preparing the alloy powder, a conventionally used method for producing metal powder can be used. For example, an atomizing method in which fluid is sprayed and dispersed by solidifying the molten alloy, a pulverizing method in which the molten alloy is solidified and then mechanically pulverized, or a mechanical alloy in which metal powder is mixed and repeatedly pressed and pulverized to form an alloy. An appropriate method such as an inging method or a melt spinning method in which a molten alloy is allowed to flow down on a rotating roll to be solidified can be used.

  As a method for preparing the alloy powder, an atomizing method is preferable, a gas atomizing method is more preferable, and a gas atomizing method performed in an inert gas atmosphere using an inert gas as a fluid is more preferable. According to such a preparation method, it is possible to prepare an alloy powder having a high sphericity and a small amount of impurities. When the sphericity of the alloy powder is increased, the resistance at the time of spreading the alloy powder in additive manufacturing can be suppressed, so that the unevenness of the alloy powder can be reduced. In addition, by using an inert gas, mixing of oxide impurities and the like is suppressed, so that the metal structure of the manufactured alloy material can be made more uniform.

  The alloy powder can have an appropriate particle size according to a melting condition such as a method of spreading the alloy powder in additive manufacturing and an output of a heat source for melting the alloy powder. However, normally, the particle size distribution of the alloy powder is preferably in the range of 1 μm to 500 μm. This is because if the particle diameter of the alloy powder is 1 μm or more, rolling-up or floating of the alloy powder is suppressed, or the oxidation reactivity of the metal is suppressed, and the risk of dust explosion or the like is reduced. On the other hand, if the particle diameter of the alloy powder is 500 μm or less, it is advantageous in that the surface of the solidified layer formed in the layered manufacturing tends to be smooth. In addition, it becomes possible to suppress the output of the heating means for melting the alloy powder, and it becomes easy to control the melting rate of the alloy powder and the range of the heated region when locally heating the alloy powder. It is possible to easily ensure the modeling accuracy of the body and the uniformity of the solidified structure.

  Drawing 1 is a key map showing an example of a process of a manufacturing method of an alloy structure concerning this embodiment.

  In the manufacturing method of the alloy structure according to the present embodiment, the three-dimensional modeling of the alloy structure is performed by repeatedly performing the layered modeling process shown in order from FIGS. The additive manufacturing process can be performed using a metal additive manufacturing apparatus generally used for metal, and the alloy powder prepared in the powder preparation process is a raw material for such additive manufacturing process. Used as a powder. As the heating means provided in the layered manufacturing apparatus, for example, those based on an appropriate heating principle such as electron beam heating, laser heating, microwave heating, plasma heating, condensing heating, and high-frequency heating are used. Among these, an additive manufacturing apparatus using electron beam heating or laser heating is particularly suitable. This is because electron beam heating or laser heating makes it relatively easy to control the output of the heat source, miniaturization of the heated area of the alloy powder, and modeling accuracy of the alloy structure.

  In detail, the layered modeling process includes a powder spreading process and a solidified layer modeling process. In the additive manufacturing process, a layered solidified structure (solidified layer) is formed through steps as shown in order from FIGS. 1A to 1G, and the formation of the layered solidified structure (solidified layer) is repeated. Then, an alloy structure comprising a set of solidified structures is formed.

  As shown in FIG. 1A, the additive manufacturing apparatus is provided with a vertically movable piston having a substrate mounting table 21 at the upper end. A processing table 22 that does not interlock with the piston is provided around the substrate mounting table 21, and a powder feeder (not shown) that supplies the raw material powder 10 onto the processing table 22 and the supplied raw material powder 10 are spread. A recoater 23, a heating means 24 for heating the raw material powder 10, an air blast (not shown) for removing the raw material powder 10 on the processing table 22, a temperature controller (not shown), and the like. The processing table 22 and these devices are housed in a chamber, and the atmosphere in the chamber is a vacuum atmosphere or an inert gas atmosphere such as argon gas depending on the type of the heating means 24, and the atmospheric pressure and temperature are set. It has come to be managed. When performing layered modeling, the base material 15 is previously placed on the base material placing table 21 and aligned so that the surface to be shaped (upper surface) of the base material 15 and the upper surface of the processing table 22 are flush with each other. .

  As the base material 15, an appropriate material can be used as long as it has heat resistance against heating by the heating means 24. In this method for manufacturing an alloy structure, a modeled product in which the base material 15 and the alloy structure are integrated is obtained by performing layered modeling of the alloy structure on the surface to be modeled of the base material 15. Will be obtained. Therefore, as the base material 15, a base material 15 having an appropriate shape such as a flat plate shape can be used on the assumption that the base material 15 is separated from the alloy structure by cutting or the like. Alternatively, assuming that the base material 15 and the alloy structure are functioned in an integrated state, a structural member, a mechanism member or the like having an arbitrary shape can be used as the base material 15.

  In the powder spreading step, the prepared alloy powder 10 is spread on the surface to be shaped. That is, in the first powder spreading process in the layered modeling, the alloy powder 10 is spread on the base material 15 placed on the layered modeling apparatus. As shown in FIG. 1B, the spreading of the alloy powder 10 is performed by using the alloy powder 10 (see FIG. 1A) supplied on the processing table 22 by a powder feeder (not shown) and forming the recoater 23 on the model. It can be performed by sweeping over the surface (base material 15) and spreading the alloy powder 10 in a thin layer. The thickness of the thin layer of the alloy powder 10 formed by spreading can be appropriately adjusted according to the output of the heating means for melting the alloy powder 10, the average particle diameter of the alloy powder 10, etc. Is in the range of about 10 μm to 1000 μm.

  In the solidified layer forming step, the spread alloy powder 10 is locally heated and melted and then solidified, and the solidified layer is scanned by scanning the heated region by the local heating with respect to the plane on which the alloy powder 10 is spread. Model 40. The modeling of the solidified layer 40 (see FIG. 1E), which will be described later, is performed according to the two-dimensional shape information obtained from the three-dimensional shape information (3D-CAD data, etc.) representing the three-dimensional shape of the alloy structure to be manufactured. This is done by scanning the area to be heated by the heating means 24. The two-dimensional shape information specifies the shape of each thin layer when the three-dimensional shape of the alloy structure to be manufactured is virtually sliced at a predetermined thickness interval and divided into a plurality of thin layer sets. Information. According to such two-dimensional shape information, the solidified layer 40 having a predetermined two-dimensional shape and thickness is formed.

  As shown in FIG. 1C, the local heating of the alloy powder 10 is performed by limiting the heated region on the spread alloy powder 10 by the heating means 24, and one of the spread alloy powder 10. This is performed by selectively melting the part so that a small molten pool (melting part 20) is formed. The size of the melting part 20 formed by melting the alloy powder 10 is preferably 1 mm or less. By limiting the melted portion 20 to such a small size, the modeling accuracy of the alloy structure and the uniformity of the element composition in the solidified structure can be improved.

  The area to be heated by local heating of the alloy powder 10 is scanned so as to move parallel to the surface to be shaped, as shown in FIG. Scanning of the heated region can be performed by scanning the irradiation spot of the heat source by a galvano mirror or the like in addition to scanning of the main body of the heating means 24, and is performed by an appropriate method such as raster scanning. At this time, overlapped scanning with a plurality of radiation sources may be performed to flatten the irradiated energy density. And by scanning the heated area, the local heating of the area where the alloy powder 10 has not yet melted is newly performed, and the heating of the area where the alloy powder 10 has already melted and the melted portion 20 is formed is stopped, The melting part 20 is cooled and solidified at ambient temperature. The solidified part 30 formed by the solidification of the melting part 20 forms a dense assembly of the solidified part 30 while being integrated with the base material and the already formed solidified part 30.

  The scanning speed, output, energy density, and scanning width of the heating means 24 are estimated from the elemental composition of the alloy powder 10, the particle size distribution, the material of the base material 15, the positional relationship between the molten portion 20 and the solidified portion 30, the chamber temperature, and the like. What is necessary is just to adjust suitably based on the heat conduction and heat radiation to be. Further, the cooling temperature for cooling the melting part 20 may be set in consideration of dimensional change, thermal strain, etc. according to the elemental composition of the alloy structure. By maintaining the size of the melting part 20, the melting rate, the cooling rate, the time interval of melting and cooling, etc. within a predetermined range, the strength distribution of the alloy structure to be shaped is made uniform, It is possible to reduce residual stress and surface roughness.

  As shown in FIGS. 1C to 1E, by forming a set of solidified portions 30 by repeatedly melting and solidifying the alloy powder 10 on the substrate 15 placed on the substrate placing table 21. The solidified layer 40 having a predetermined two-dimensional shape and thickness is formed. After the unmelted alloy powder 10 remaining around and on the upper surface of the formed solidified layer 40 is removed by air blasting, the substrate mounting table 21 is formed on the formed solidified plate as shown in FIG. The height corresponding to the thickness of the layer 40 is lowered, and the new surface to be formed on the upper surface of the solidified layer 40 is aligned with the upper surface of the processing table 22.

  After the alignment, a powder spreading process is performed in the same manner as in FIGS. 1A to 1B. As shown in FIG. 1G, a new surface is newly formed on the upper surface of the solidified layer 40 that has already been formed. The supplied alloy powder 10 is spread. Thereafter, the solidified layer forming process is performed in the same manner as in FIGS. 1C to 1E, and the next solidified layer 40 is laminated. The laminated solidified portion 30 is integrated with a part of the lower solidified layer 40 and sintered densely. Thereafter, in the same manner, by repeating the powder spreading process and the solidified layer modeling process in which the upper surface of the formed solidified layer 40 is the modeled surface, an alloy structure having a desired shape and dimension can be layered.

  In the solidified layer forming step, after the alloy powder 10 is melted, the solidified portion 30 to the solidified layer 40 can be shaped and surface-treated in a high temperature state until the solidified portion 30 is formed. . Such processing is performed in a state where the surface temperature of the melted part 30 to the solidified part 40 is about 500 ° C. or higher, preferably in a temperature range of 50% to 75% of the melting point (Tm) of the alloy, for example, metal or alloy It can be performed by processing using a tool made of an inorganic or inorganic composite material such as a diamond tool, an intermetallic compound powder, or a green compact such as tungsten carbide. By such processing, it is possible to form or decorate an alloy structure which is difficult to process into a more accurate shape and size.

  A hot isostatic pressing (HIP) process may be separately performed on the alloy structure that has been layered by repeating the powder spreading process and the solidified layer modeling process. This is because by subjecting the alloy structure to hot isostatic pressing, the solidified structure of the alloy structure can be made denser or defects in the solidified structure can be removed.

  According to the method of manufacturing an alloy structure in which three-dimensional modeling is performed by repeatedly performing such a layered manufacturing process, an alloy structure having a columnar crystal as a main crystal is manufactured with a desired shape and size by a collection of minute solidification structures. Can do. In addition, each elemental composition of the minute solidified structure (solidified part 30) reflects the elemental composition of the alloy powder used well, so the uniformity of the elemental composition distribution and the mechanical strength distribution are A high solid solution phase can be formed. Furthermore, since a solidified structure (solidified portion 30) is formed by heating from one direction and a solidified structure (solidified layer 40) in which the crystal growth direction is oriented substantially in one direction can be laminated, the anisotropy is high. An alloy structure can be formed.

  Next, the metal structure of the alloy structure formed by additive manufacturing will be described.

  FIG. 2 is a cross-sectional view showing the outline of the metal structure of the alloy structure. (A) is sectional drawing of the alloy structure which concerns on this embodiment, (b) is an expanded sectional view of the A section in (a), (c) is the outline of the metal structure which the alloy material which concerns on a comparative example has It is sectional drawing which showed.

  As shown in FIG. 2 (a), the alloy structure 1 according to the present embodiment has a solidified structure (solidified) formed by solidification of a molten alloy having a metal structure derived from the manufacturing method by additive manufacturing. Part 30). In FIG. 2A, a cross section is shown by extracting a part of an alloy structure manufactured by additive manufacturing. Each solidified structure (solidified portion 30) has a substantially hemispherical original shape derived from the contour shape of the molten pool (molten portion 20) by local heating, and is integrated with other solidified portions 30 around it. A dense metal structure is formed. In addition, the solidified portions 30 are two-dimensionally arranged with the arc side facing in the same direction to form a layered solidified layer 40 that is a set of the solidified portions 30. A large number of solidified layers 40 formed in this way are stacked, thereby forming a metal structure in which the solidified portions 30 are arranged in a three-dimensional manner. However, depending on modeling conditions such as scanning speed and scanning width in the layered modeling, the solidified part 30 forming the solidified layer 40 may be integrated with other solidified parts 30 around the same layer, or the string side of each solidified part 30 may be In some cases, the solidified layer 40 may be integrated with the other solidified layers 40, so that the substantially hemispherical original shape of the solidified part and the melting boundary 100 between the solidified parts 30 may not be observed in the solidified structure. .

  As shown in FIG. 2B, the alloy structure 1 has a columnar crystal in which a non-Fe main component element and Fe are dissolved as a main crystal. In FIG. 2 (b), the cross section of the metal structure of the alloy structure is shown enlarged to a viewing angle of several hundred μm to several mm. Each crystal grain 50 included in the metal structure of the alloy structure is epitaxially grown so that the crystal orientation is substantially along the stacking direction of the solidified layer 40, and the grain boundary 110 (high tilt grain boundary) is directed in the stacking direction. A structure that extends beyond the melting boundary 100 between the solidified portions 30 is formed.

  Each crystal grain 50 may be refined to an average crystal grain size of 10 μm or less. The refined crystal grains 50 maintain the crystal orientation, and the small-angle grain boundary 120 may be recognized on the inner side partitioned by the large-angle grain boundary 110. Note that the low-inclination grain boundary 120 is defined as a grain boundary having an inclination angle of 15 ° or less, and the large-inclination grain boundary 110 is defined as a grain boundary having an inclination angle exceeding 15 °. The refined crystal grains 50 tend to be a collection of crystal grains having a small twist angle as well as an inclination angle.

  On the other hand, the conventional high entropy alloy material (alloy material according to the comparative example) has a metal structure derived from a manufacturing method by casting. In the alloy material according to the comparative example, as shown in FIG. 2 (c), isotropic grain boundaries 110 are observed, and coarse equiaxed crystal grains having an average crystal grain size exceeding 100 μm are formed. Tend. In FIG. 2 (c), the cross section of the metal structure of the alloy material is shown enlarged to a viewing angle of several hundred μm to several mm. In the alloy material according to the comparative example, segregation is likely to occur due to the nucleus growth, the uniformity of the composition distribution is low, the stress is not easily dispersed because the crystal grains are coarse, and the surface that causes cleavage and slip is long. Therefore, the mechanical strength is not sufficient. In particular, since a solid solution phase cannot grow well, there is a difficulty that a complicated shape cannot be formed with a small size.

  On the other hand, the alloy structure according to the present embodiment is composed of a set of crystal grains 50 in which crystals having relatively uniform crystal orientations grow epitaxially and grow well in an equivalent environment. The elemental composition thus formed is easily maintained regardless of the shape and size of the alloy structure, and the uniformity of the composition distribution is increased. Further, there is an advantage that the crystal grains 50 are miniaturized, strain due to stress is hardly concentrated locally, and the uniformity of mechanical strength is increased. Moreover, since the surface that causes cleavage and slipping is short, it is advantageous in that the mechanical strength is improved. Furthermore, since the crystal growth direction is oriented and the anisotropy is increased, it is also effective in utilizing the direction strength and magnetic characteristics.

  Next, an example of the manufacturing method of the alloy powder used as the alloy structure raw material according to the present embodiment will be described.

  FIG. 3 is a schematic flow chart showing an example of a method for producing an alloy powder used as a raw material for an alloy structure.

  As described above, the effects of the elemental composition of the alloy powder used in additive manufacturing are easily reflected in the various characteristics of the alloy structure according to the present embodiment. Therefore, it is preferable that the alloy powder used as a raw material has an elemental composition in which the concentration of inevitable impurities is reduced. As a method for producing the alloy powder, a vacuum carbon deoxidation capable of producing an alloy having a high cleanliness is provided. It is preferable to use a manufacturing method by complex refining using the method. The method for producing the alloy powder shown in FIG. 3 performs cleansing outside the furnace using a ladle, and uses clean metal as raw metal to perform complex smelting using a vacuum carbon deoxidation method to achieve cleanliness. It is a method of refining a high alloy and preparing an alloy powder using the alloy, and is a method that can be applied as the preparation step of the alloy powder.

  In this manufacturing method, as shown in FIG. 3 (a), first, a melting process is performed in which an electric furnace 301 melts a metal block 302 of a crude metal that is a raw material for alloy powder. In FIG. 3, the electric furnace 301 is a three-phase AC arc furnace including an electrode 304 such as a carbon electrode that generates arc discharge in the furnace and an oxygen burner 305 that blows oxygen gas into the furnace. However, it is also possible to use a DC arc furnace, a converter, or the like having an equivalent configuration.

  As the metal lump 302, metal scrap, iron scrap or the like can be used. It is preferable that the type of metal block 302 is blended so as to have an elemental composition compatible with the alloy powder to be manufactured, and a type with few impurity elements is selected in advance. When it is not contained as a non-Fe main component element, it is possible to select a type in which Sn is 0.005 wt% or less, Sb is 0.002 wt% or less, and As is 0.005 wt% or less. preferable.

  In the melting process, as shown in FIG. 3A, the metal lump 302 is put into the furnace of the electric furnace 301, and an arc discharge 303 is generated between the electrode 304 and the metal lump 302, thereby causing the metal lump 302. To make a molten metal 310. And as shown in FIG.3 (b), the peroxidation process which forms slag by blowing oxygen gas 306 into the molten metal 310 with the oxygen burner 305 is performed. Thus, by performing the peroxidation process which blows oxygen into the molten metal 310, impurity elements, such as Si, Mn, and P contained in the molten metal 310, can be transferred into the slag as oxides. There is also an advantage that the amount of electric power for heating the molten metal 310 with the combustion heat of oxygen can be reduced.

  After slag is formed in the molten metal 310, the molten metal 310 is discharged from the outlet 308 of the electric furnace 301 and transferred to the ladle 309 as shown in FIG. At this time, the slag containing a large amount of impurity elements floating on the liquid surface of the molten metal 310 is separated from the molten metal 310 and the slag so as not to move to the ladle 309, and the concentration of impurity elements such as Si, Mn, and P is increased. A lowered molten metal 310 is obtained.

  Subsequently, as shown in FIG. 3D, the molten metal 310 is discharged from the bottom of the ladle 309 and transferred to the ladle refining furnace 311. The ladle refining furnace 311 includes a porous plug 313 at the bottom, and argon bubbling is performed when argon gas 314 is fed into the furnace through a porous plug 313 from a gas supply (not shown). Yes. By performing argon bubbling, the molten metal 310 transferred to the ladle refining furnace 311 is homogenized by stirring, and impurity elements such as O and N are degassed.

  In the ladle refining furnace 311, as shown in FIG. 3E, first, the primary heat treatment of the molten metal 310 is performed. The molten metal 310 transferred to the ladle refining furnace 311 is heated by generating an arc discharge at the electrode 304, and the bottom blowing argon bubbling through the porous plug 313 is continuously performed, so that the elemental component and temperature can be adjusted. It can be made uniform.

  Subsequently, as shown in FIG. 3 (f), the molten metal 310 is degassed using a vacuum degasser 316. The vacuum degassing device 316 depressurizes the inside of the device through an exhaust hole 317 connected to a vacuum pump (not shown), and sucks up the molten metal 310 by moving up and down relative to the ladle refining furnace 311. In this apparatus, the gas contained in the molten metal 310 is degassed. In addition, in FIG. 3, although the DH vacuum degassing furnace (Dortmund Hoerde type | mold) which has one dip tube is shown typically as the vacuum degassing apparatus 316, it is a ladle made with the shroud which does not have a dip tube. The smelting furnace 311 may be covered, or an RH vacuum degassing furnace (Ruhrstahl Heraeus type) or an RH injection furnace may be used.

  In the degassing treatment, the gas of the impurity element degassed from the molten metal 310 can be efficiently exhausted by performing argon bubbling in a state where the gas-phase atmosphere in the apparatus is decompressed by the vacuum degassing apparatus 316. it can. During the degassing process, the molten metal 310 is heated by a heater (not shown) to prevent the temperature from being lowered, and desulfurization powder is appropriately injected into the molten metal 310. By subjecting the molten metal 310 to such degassing treatment, the molten metal 310 in which the concentration of impurity elements such as S, O, and H is reduced is obtained.

  Subsequently, in the ladle refining furnace 311, as shown in FIG. 3G, secondary heat treatment of the molten metal 310 is performed. In the secondary heat treatment, the elemental composition and temperature of the molten metal 310 are finally adjusted.

  Then, as shown in FIG.3 (h), the molten metal 310 of the ladle refining furnace 311 is cast-processed. The molten metal 310 is discharged from the bottom of the ladle refining furnace 311 and transferred to the tundish 318, where the impurity elements are separated as slag. Then, the molten metal 310 is discharged from the bottom of the tundish 318 and poured into a mold 321 installed in the vacuum vessel 319. A vacuum pump (not shown) is connected to the vacuum container 319 through an exhaust hole 320 so that the inside of the container in which the mold 321 is installed is in a reduced pressure atmosphere. Thus, when the molten metal 310 poured into the mold 321 is cooled, an alloy lump 322 having an arbitrary shape is cast. By casting the molten metal 310 in a reduced-pressure atmosphere, an alloy having a reduced concentration of impurity elements such as N, O, and H can be obtained.

  The alloy refined by the method as described above can be used as a bare metal for preparing the alloy powder used in the powder preparation step. Due to complex smelting using vacuum carbon deoxidation method, it has become a highly clean alloy with reduced impurity element concentration, so it is composed of particles with a high uniformity of elemental composition distribution, It is suitable for preparing an alloy powder having high uniformity. From the viewpoint of maintaining the cleanliness of the alloy refined as described above, it is preferable to perform a pulverization process using a vacuum carbon deoxidation method in preparing the alloy powder.

  The powdering process using the vacuum carbon deoxidation method can be performed using a vacuum furnace 324 directly connected to a gas atomizer as shown in FIG. The vacuum furnace 324 includes an electric furnace having an electrode 304 for generating arc discharge in the furnace, a gas injection lance (not shown) for blowing argon gas into the furnace, and an exhaust hole (not shown) to which a vacuum pump is connected. Is done. A nozzle 328 is provided at the bottom of the vacuum furnace 324, and an atomizing chamber 330 is provided below the nozzle 328 so as to cover the outlet of the nozzle 328 in an airtight manner. Further, a gas injection hole 329 for blowing an inert gas such as argon gas to the molten metal 326 flowing down from the nozzle 328 is provided on the exit side of the nozzle 328.

  In the vacuum furnace 324, the alloy obtained by the above-described composite refining is put into the furnace, and arc discharge is generated between the electrode 304 and the alloy, thereby forming a molten alloy 326 of the alloy. In addition, the temperature of the molten metal 326 to be heated is in a temperature range exceeding 1600 ° C. and not more than 2500 ° C. The molten metal 326 is degassed while performing argon bubbling under a reduced pressure atmosphere by a vacuum pump connected to an exhaust hole (not shown), and the concentration of impurity elements such as N, O, and H is further reduced. . Then, the molten metal 326 that has been degassed and in which the cleanliness is maintained flows down from the nozzle 328. Thereafter, the molten metal 328 that has flowed down is turned into fine particles by spraying an inert gas injected from the gas injection holes 329, solidifies in the atomizing chamber 330, and accumulates as powder 331 at the bottom.

The vacuum furnace 324 may be a heat-resistant and fire-resistant heating furnace so that a high-entropy alloy having a relatively high melting point can be melted, and the furnace wall may be a water-cooled type or the like. Examples of the furnace wall of the vacuum furnace 324 include graphite (graphite), quartz (SiO ₂ ), alumina (Al ₂ O ₃ ), magnesia (MgO), Al ₂ O ₃ .SiO ₂ .Fe ₂ O ₃ .Na _2. Alumina ceramics composed of mixed sintered bodies such as O, mullite ceramics composed of mixed sintered bodies such as Al ₂ O ₃ · SiO ₂ · Fe ₂ O ₃ · TiO ₂ , Al ₂ O ₃ · MgO · SiO ₂ · magnesia ceramics consisting of a mixture sintered body such as _{CaO · Fe 2 O 3, Al} 2 O 3 · MgO · ZrO 2 · SiO 2 · CaO · Fe 2 O 3 · TiO 2 zirconia comprising a mixed sintered body such as _{ceramic, Al 2 O 3 · MgO ·} SiO 2 · CaO · Fe 2 O 3 spinel ceramics consisting of a mixture sintered body such _{as, Al 2 O 3 · MgO ·} SiO 2 · CaO · Fe 2 O 3 mixed sintered such Calci consisting of union It is preferred to apply the quality ceramics, siliceous ceramics consisting of _{Al 2 O 3 · SiO 2 ·} Fe 2 O 3 · TiO 2 mixed sintered body such as. In particular, when melting in an ultrahigh temperature range of about 1000 ° C. or higher, it is preferable to perform coating with a carbide such as TiC, ZrC, HfC, NbC, and TaC.

  FIG. 4 is a diagram showing an example of a change in impurity element concentration in an alloy powder prepared using a vacuum carbon deoxidation method.

  In FIG. 4, in the process of refining an alloy using the vacuum carbon deoxidation method and preparing the alloy powder by pulverizing the alloy, the concentration change of the impurity element contained in the metal powder is shown. It is shown as measured over time. The period A corresponding to the elapsed time 1.5 h to 2.8 h corresponds to the peroxidation treatment in the electric furnace 301 (see FIG. 3B), and the period B1 corresponding to the elapsed time 2.8 h to 6 h is , Which corresponds to the primary heat treatment in the ladle refining furnace 311 (see FIG. 3E), and during the B2 period corresponding to the elapsed time 6h to 6.5h, the degassing process in the ladle refining furnace 311 (FIG. 3 ( The period B3 corresponding to the elapsed time 6.5h to 8.2h corresponds to the secondary heat treatment in the ladle refining furnace 311 (see FIG. 3G), and the elapsed time 8. The C period corresponding to 2h or later corresponds to the degassing process in the vacuum furnace 324 (see FIG. 3 (i)).

  As shown in FIG. 4, by using the vacuum carbon deoxidation method, when performing the secondary heat treatment in the ladle refining furnace 311, 0.18 wt% for C, 0.01 wt% for Si, Mn The concentration decreases to 0.019 wt% for P, 0.001 wt% for P, 0.001 wt% for S, and when degassing treatment is performed in the vacuum furnace 324, 0.0003 wt% (3 ppm) for O, It can be seen that the concentration of N can be reduced to 0.001 wt% (10 ppm). As described above, in the process of preparing the alloy powder using the vacuum carbon deoxidation method, the number of slag separation, the time of degassing treatment, and the like are adjusted as appropriate, so that P, Si, S, Sn, Sb, As It is possible to limit the concentration of impurity elements such as Mn, O, and N to a desired range. In addition, when the P, Si, Sn, Sb, As, or Mn element is included in the alloy structure as a non-Fe main component, the metal is selected in anticipation of a decrease in concentration during the refining process, or slag What is necessary is just to adjust the frequency | count of isolation | separation etc. suitably.

The alloy structure according to this embodiment can be applied as a structural member, a mechanism member, or the like. As long as the layered manufacturing is possible, the shape can be any shape, and the length can be any dimension exceeding 70 mm and the volume exceeding 5495 mm ³ . In addition to applications in normal environments, it can be used in applications in severe environments such as high temperature environments, high radiation dose environments, and highly corrosive environments. Further, since the atomic diffusion rate under high temperature is slow and the physical properties can be stably maintained, it can be suitably used for applications that are left in a high temperature environment for a long time. More specifically, for example, plant structural materials including casings, piping, valves, etc., generator structural materials, nuclear reactor structural materials, aerospace structural materials, hydraulic equipment members, turbine blades, etc. It can be used for applications such as turbine members, boiler members, engine members, nozzle members, and mechanical members of various devices such as bearings and pistons. In addition, the alloy structure according to the present embodiment is applied so as to cover the surface of a structure such as a metal or alloy structural member or mechanism member, thereby providing a heat resistant coating, a corrosion resistant coating, an abrasion resistant coating, It can also be used as a diffusion barrier layer or the like serving as an atomic diffusion barrier. It can also be applied to tools such as Friction Stir Welding (FSW) processing tools, and it can be used for a wide range of applications including friction stir welding of ferrous materials that require high-temperature strength and wear resistance. It can be suitably used.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using the Example of this invention, the technical scope of this invention is not limited to this.

  As examples of the present invention, alloy structures according to Examples 1-1 to 1-4 and Examples 2-1 to 2-3 are manufactured, and observation of solidified structure, elemental composition distribution, mechanical The characteristics were evaluated. Moreover, the alloy structure which concerns on Comparative Example 1-1-Comparative Example 1-4 and Comparative Example 2-1-Comparative Example 2-4 as a control | contrast of an Example was manufactured, and also evaluated.

[Example 1-1]
As Example 1-1, an alloy structure whose element composition is represented by Al _0.3 CoCrFeNi was manufactured by additive manufacturing. The atomic concentration ratio is such that the atomic concentration of Al is about 7 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 23.3 at%.

  First, an alloy powder was prepared by a gas atomizing method using an alloy having an atomic concentration of Al of about 7 at% and an atomic concentration of Co, Cr, Fe, and Ni of about 23.3 at% as a bare metal. The obtained alloy powder was classified so that the particle size distribution was limited to a range of 50 μm or more and 100 μm or less, and the volume-based average particle size was about 70 μm.

  Subsequently, an alloy structure was modeled on the base material using an additive manufacturing apparatus. As the base material, a plate-like carbon steel for mechanical structure “S45C” of 100 mm × 100 mm × 10 mm was used. Further, as the additive manufacturing apparatus, an electron beam melt additive manufacturing apparatus “A2X” (manufactured by Arcam) using an electron beam as a heat source was used. In the layered manufacturing apparatus, a cylindrical alloy structure having a diameter of 10 mm and a height of 50 mm was manufactured by repeatedly performing a powder spreading process and a solidified layer modeling process on a base material in a vacuum atmosphere. At this time, the melting of the alloy powder was performed while preheating at a temperature of 50% to 80% of the melting point (Tm) of the alloy was performed in advance to suppress the spread of the spread alloy powder. Thereafter, the alloy structure was separated from the substrate.

[Example 1-2]
As Example 1-2, an alloy structure having an element composition represented by AlCoCrFeNi was manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%.

  The alloy structure according to Example 1-2 was manufactured in the same manner as Example 1-1 except that the composition of the metal used for preparing the alloy powder was changed.

[Comparative Example 1-1]
As Comparative Example 1-1, an alloy structure having an elemental composition represented by Al _0.3 CoCrFeNi was manufactured by casting. The atomic concentration ratio is such that the atomic concentration of Al is about 7 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 23.3 at%.

  First, an alloy powder was prepared by a gas atomizing method using an alloy having an atomic concentration of Al of about 7 at% and an atomic concentration of Co, Cr, Fe, and Ni of about 23.3 at% as a bare metal. The obtained alloy powder was classified so that the particle size distribution was limited to a range of 50 μm or more and 100 μm or less, and the volume-based average particle size was about 70 μm.

  Subsequently, the obtained alloy powder was put into an alumina crucible, dissolved in a vacuum atmosphere by high frequency induction heating, poured into a copper water-cooled mold, cooled and solidified to obtain a diameter. A cylindrical alloy structure having a size of 10 mm and a height of 50 mm was manufactured.

[Comparative Example 1-2]
As Comparative Example 1-2, an alloy structure having an element composition represented by Al _0.2 CoCrFeNi was manufactured by additive manufacturing. The atomic concentration ratio is such that the atomic concentration of Al is about 4.8 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 23.8 at%.

  The alloy structure according to Comparative Example 1-2 was manufactured in the same manner as in Example 1-1 except that the composition of the metal used for preparing the alloy powder was changed.

[Example 1-3]
As Example 1-3, an alloy structure having an element composition represented by Al _1.5 CoCrFeNi was manufactured by additive manufacturing. The atomic concentration ratio is such that the atomic concentration of Al is about 27.2 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 18.2 at%.

  First, an alloy powder was prepared by a gas atomization method using an alloy having an atomic concentration of Al of about 27.2 at% and an atomic concentration of Co, Cr, Fe, and Ni of about 18.2 at% as a bare metal. The obtained alloy powder was classified so that the particle size distribution was limited to a range of 20 μm or more and 50 μm or less, and the volume-based average particle size was about 30 μm.

  Subsequently, an alloy material was modeled on the base material using an additive manufacturing apparatus. As a base material, carbon steel “S45C” having a diameter of 10 mm and a height of 50 mm and having a cylindrical shape for mechanical structure was used. Further, as the additive manufacturing apparatus, a laser melt additive manufacturing apparatus “EOSINT M270” (manufactured by EOS) using a laser beam as a heat source was used. In the layered modeling apparatus, a 200 μm multilayer alloy material was manufactured by repeatedly performing a powder spreading process and a solidified layer modeling process on a substrate in a nitrogen atmosphere.

[Comparative Example 1-3]
As Comparative Example 1-3, an alloy structure having an element composition represented by AlCoCrFeNi was manufactured by thermal spraying. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%.

  First, each metal powder of Al, Co, Cr, Fe, and Ni was mixed so that the atomic concentration of Al, Co, Cr, Fe, and Ni was about 20.0 at%. Each metal powder was classified so that the particle size distribution was limited to the range of 50 μm or more and 150 μm or less, and the volume-based average particle size was about 70 μm.

  Subsequently, the mixed metal powder was sprayed on a base material by a plasma spraying method in a nitrogen atmosphere to produce a 200 μm film-like alloy structure. As the base material, a carbon steel “S45C” having a diameter of 100 mm and a height of 10 mm and having a cylindrical shape for mechanical structure was used.

[Comparative Example 1-4]
As Comparative Example 1-4, an alloy structure having an elemental composition represented by Al _2.0 CoCrFeNi was manufactured by additive manufacturing. The atomic concentration ratio is such that the atomic concentration of Al is about 33.3 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 16.7 at%.

  The alloy structure according to Comparative Example 1-4 was manufactured in the same manner as in Example 1-2, except that the composition of the metal used for preparing the alloy powder was changed.

[Example 1-4]
As Example 1-4, an alloy structure having an element composition represented by AlCoCrFeNiMo _0.5 was manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 18.2 at%, and the atomic concentration of Mo is about 9.1 at%.

  First, an alloy powder was prepared by a gas atomization method using an alloy having an atomic concentration of Al, Co, Cr, Fe, and Ni of about 18.2 at% and an atomic concentration of Mo of about 9.1 at% as a bare metal. . The obtained alloy powder was classified so that the particle size distribution was limited to a range of 50 μm or more and 100 μm or less, and the volume-based average particle size was about 70 μm.

  Subsequently, an alloy structure was modeled on the base material using an additive manufacturing apparatus. As the base material, a carbon steel for structural use “S45C” having a diameter of 300 mm and a height of 10 mm was used. Further, as the additive manufacturing apparatus, an electron beam melt additive manufacturing apparatus “A2X” (manufactured by Arcam) using an electron beam as a heat source was used. In the additive manufacturing apparatus, an approximately cylindrical impeller-shaped alloy structure having a diameter of 300 mm and a height of 100 mm was manufactured by repeatedly performing a powder spreading process and a solidified layer forming process on a base material in a vacuum atmosphere. . At this time, the melting of the alloy powder was performed while preheating at a temperature of 50% to 80% of the melting point (Tm) of the alloy was performed in advance to suppress the spread of the spread alloy powder. Thereafter, the impeller-shaped alloy structure was cut off from the base material.

[Example 2-1]
As Example 2-1, an alloy structure in which the elemental composition was expressed by Al _0.3 CoCrFeNi and the concentration of inevitable impurities was limited was manufactured by additive manufacturing. The atomic concentration ratio is such that the atomic concentration of Al is about 7 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 23.3 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  The alloy structure according to Example 2-1 was manufactured in the same manner as in Example 1-1 except that the composition of the metal used for preparing the alloy powder was changed.

[Example 2-2]
As Example 2-2, an alloy structure in which the elemental composition is expressed by AlCoCrFeNi and the concentration of inevitable impurities is limited is manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  The alloy structure according to Example 2-2 was manufactured in the same manner as in Example 1-1 except that the composition of the metal used for preparing the alloy powder was changed.

[Comparative Example 2-1]
As Comparative Example 2-1, an alloy structure having an element composition represented by AlCoCrFeNi and limiting the concentration of inevitable impurities was manufactured by casting. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  The alloy structure according to Comparative Example 2-1 was manufactured in the same manner as Comparative Example 1-1 except that the composition of the metal used for preparing the alloy powder was changed.

[Comparative Example 2-2]
As Comparative Example 2-2, an alloy structure having an elemental composition represented by Al _0.2 CoCrFeNi and limiting the concentration of inevitable impurities was manufactured by casting. The atomic concentration ratio is such that the atomic concentration of Al is about 4.8 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 23.8 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  The alloy structure according to Comparative Example 2-2 was manufactured in the same manner as Example 1-1, except that the composition of the metal used for preparing the alloy powder was changed.

[Example 2-3]
As Example 2-3, an alloy structure in which the elemental composition is expressed by Al _1.5 CoCrFeNi and the concentration of inevitable impurities is limited is manufactured by additive manufacturing. The atomic concentration ratio is such that the atomic concentration of Al is about 27.2 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 18.2 at%. Further, the P concentration is 0.005 wt% or less, the Si concentration is 0.040 wt% or less, the S concentration is 0.002 wt% or less, the Sn concentration is 0.005 wt% or less, and the Sb concentration is 0.002 wt%. Hereinafter, the As concentration was limited to 0.005 wt% or less, the Mn concentration was 0.050 wt% or less, the O concentration was 0.001 wt% or less, and the N concentration was 0.002 wt% or less.

  First, the atomic concentration of Al is about 27.2 at%, the atomic concentration of Co, Cr, Fe and Ni is about 18.2 at%, the P concentration is 0.005 wt% or less, and the Si concentration is 0.040 wt%. Hereinafter, the S concentration is 0.002 wt% or less, the Sn concentration is 0.005 wt% or less, the Sb concentration is 0.002 wt% or less, the As concentration is 0.005 wt% or less, and the Mn concentration is 0.050 wt%. Hereinafter, an alloy powder was prepared by a gas atomization method using an alloy in which the concentration of O was limited to 0.001 wt% or less and the concentration of N was limited to 0.002 wt% or less as a bare metal. The obtained alloy powder was classified so that the particle size distribution was limited to a range of 20 μm or more and 50 μm or less, and the volume-based average particle size was about 30 μm.

  Subsequently, an alloy material was modeled on the base material using an additive manufacturing apparatus. As the base material, a carbon steel “S45C” having a diameter of 100 mm and a height of 10 mm and having a cylindrical shape for mechanical structure was used. Further, as the additive manufacturing apparatus, a laser melt additive manufacturing apparatus “EOSINT M270” (manufactured by EOS) using a laser beam as a heat source was used. In the layered modeling apparatus, a 200 μm multilayer alloy material was manufactured by repeatedly performing a powder spreading process and a solidified layer modeling process on a substrate in a nitrogen atmosphere.

[Comparative Example 2-3]
As Comparative Example 2-3, an alloy structure having an element composition represented by AlCoCrFeNi and limiting the concentration of inevitable impurities was manufactured by thermal spraying. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  First, the atomic concentration of Al, Co, Cr, Fe, and Ni is about 20.0 at%, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, and the S concentration is 0.001 wt%. Hereinafter, the Sn concentration is 0.002 wt% or less, the Sb concentration is 0.001 wt% or less, the As concentration is 0.001 wt% or less, the Mn concentration is 0.020 wt% or less, and the O concentration is 0.0003 wt%. Hereafter, each metal powder of Al, Co, Cr, Fe, and Ni in which the concentration of N was limited to 0.001 wt% or less was mixed. Each metal powder was classified so that the particle size distribution was limited to the range of 50 μm or more and 150 μm or less, and the volume-based average particle size was about 70 μm.

  Subsequently, the mixed metal powder was sprayed on a base material by a plasma spraying method in a nitrogen atmosphere to produce a 200 μm film-like alloy structure. As the base material, a carbon steel “S45C” having a diameter of 100 mm and a height of 10 mm and having a cylindrical shape for mechanical structure was used.

[Comparative Example 2-4]
As Comparative Example 2-4, an alloy structure in which the elemental composition was expressed by Al _2.0 CoCrFeNi and the concentration of inevitable impurities was limited was manufactured by additive manufacturing. The atomic concentration ratio is such that the atomic concentration of Al is about 33.3 at%, and the atomic concentrations of Co, Cr, Fe, and Ni are about 16.7 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  The alloy structure according to Comparative Example 2-4 was manufactured in the same manner as Example 2-2 except that the composition of the metal used for preparing the alloy powder was changed.

  Next, the manufactured alloy structures according to Example 1-1 to Example 1-4 and Example 2-1 to Example 2-3, and Comparative Example 1-1 to Comparative Example 1-4 and Comparative Example The alloy structure according to 2-1 to Comparative Example 2-4 was subjected to observation of a solidified structure, analysis of nickel concentration distribution, and hardness measurement. The solidified structure was observed by confirming the crystal structure and average crystal grain size with a high-resolution transmission electron microscope. In addition, the nickel concentration distribution is analyzed by using a scanning electron microscope-energy dispersive X-ray detector (SEM-EDX) to determine the nickel concentration of 10 regions arbitrarily extracted. Done by measuring. Moreover, the hardness measurement was performed by measuring Vickers hardness (Hv) about 10 points | pieces extracted arbitrarily of the alloy material. The test load was 100 gf and the holding time was 10 seconds.

  Table 1 shows the results of observation of solidified structure, analysis of nickel concentration distribution, and hardness measurement. In Table 1, the element composition column indicates the atomic concentration ratio between the main component element and the additive element. In the impurity column, “±” indicates an example in which inevitable impurities are not restricted, “−” indicates an example in which inevitable impurities are somewhat restricted, and “−−” indicates an example in which inevitable impurities are more restricted. Yes. The column “Crystal structure” indicates the crystal structure of the main crystal. “*” In the “Hardness” column indicates that a crack occurred.

  As shown in Table 1, the alloy structures according to Example 1-1 to Example 1-4 and Example 2-1 to Example 2-3 have a face-centered cubic lattice crystal structure or a body-centered cubic lattice. It was confirmed to have any one of the following crystal structures. Moreover, it can be seen from the nickel concentration distribution and hardness values that the standard deviation is small and the uniformity of the distribution of elemental composition and mechanical strength is high. Further, from the observation of the solidified structure, a solidified structure and a crystal structure as shown in FIGS. 2A and 2B were confirmed. For the alloy structure according to Example 1-4 having an impeller shape, it was separately confirmed that the amount of corrosion thinning during the salt water (artificial seawater) corrosion test is suppressed more than that of austenitic stainless steel (SUS304). It was also confirmed that it is suitable as a corrosion-resistant structural member, a corrosion-resistant mechanism member, and the like.

  On the other hand, the alloy structures according to Comparative Example 1-1 to Comparative Example 1-4 and Comparative Example 2-1 to Comparative Example 2-4 have a large standard deviation in the nickel concentration distribution and hardness values. It can be seen that the uniformity of composition and mechanical strength distribution is low. In addition, it was recognized that the crystal structure reflects the low uniformity of the elemental composition and a multiphase structure is formed. In particular, when the atomic concentration of Al is lowered, it has been found that the hardness remains lower than that of mild steel and is not suitable as a structural member, a mechanism member, or the like. Further, when the atomic concentration of Al was increased, a B2 type intermetallic compound was formed, and cracks were generated during the test, which proved unsuitable as a structural member, a mechanism member, or the like.

  In general, in structural members, mechanism members, etc., heat deterioration, wear, corrosion, etc. progress from a low-resistance region, so considering rolling, etc., both structural members, mechanism members, etc. have both hardness and ductility. It can be said that it is desirable. It can also be said that the deviation of these properties is required to be minimized. From such a viewpoint, the alloy structures according to Example 1-1 to Example 1-4 and Example 2-1 to Example 2-3, Comparative Example 1-1 to Comparative Example 1-4, and Comparative Example From the results with the alloy structure according to 2-1 to Comparative Example 2-4, the uniformity of the distribution of the elemental composition and the mechanical strength of the present invention is extremely high when the characteristics of the structural member, the mechanism member, and the like are improved. It can be said that it was confirmed that it works favorably.

  Next, as examples of the present invention, alloy structures according to Example 3-1 and Example 3-2 were manufactured, and stress-strain characteristics were evaluated.

  FIG. 5 is a diagram showing the shape and dimensions of the alloy structure according to Example 3.

[Example 3-1]
As Example 3-1, the alloy structure shown in FIG. 5 in which the elemental composition was expressed by AlCoCrFeNi and the concentration of inevitable impurities was limited was manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  First, the atomic concentration of Al is about 7 at%, the atomic concentration of Co, Cr, Fe and Ni is about 23.3 at%, the concentration of P is 0.002 wt% or less, the concentration of Si is 0.010 wt% or less, S concentration is 0.001 wt% or less, Sn concentration is 0.002 wt% or less, Sb concentration is 0.001 wt% or less, As concentration is 0.001 wt% or less, Mn concentration is 0.020 wt% or less, An alloy powder was prepared by a gas atomization method using an alloy in which the concentration of O was limited to 0.0003 wt% or less and the concentration of N was limited to 0.001 wt% or less as a bare metal. The obtained alloy powder was classified so that the particle size distribution was limited to a range of 45 μm or more and 105 μm or less, and the volume-based average particle size was about 70 μm.

Subsequently, an alloy material was modeled on the base material using an additive manufacturing apparatus. As the substrate, a plate-like carbon steel for mechanical structure “S45C” of 200 mm × 200 mm × 10 mm was used. Further, as the additive manufacturing apparatus, an electron beam melt additive manufacturing apparatus “A2X” (manufactured by Arcam) using an electron beam as a heat source was used. In the layered manufacturing apparatus, by repeatedly performing the powder spreading process and the solidified layer modeling process on a base material in a vacuum atmosphere, as shown in FIG. 5, a plate-shaped model (plate shape) of 150 mm × 150 mm × 30 mm is used. Part) was formed, and a total of 16 cuboid shaped objects (cuboid parts) of 28 mm × 28 mm × 20 mm were formed at intervals of 6 mm in length and width. At this time, the melting of the alloy powder was performed while preheating at a temperature of 50% to 80% of the melting point (Tm) of the alloy powder was performed in advance, and scattering of the spread alloy powder was suppressed. In addition, the volume of the whole molded article was 925880 mm ³ .

[Example 3-2]
As Example 3-2, the alloy structure shown in FIG. 5 in which the elemental composition is expressed by AlCoCrFeNi and the concentration of inevitable impurities is not limited was manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%.

  The alloy structure according to Example 3-2 was manufactured in the same manner as in Example 3-1, except that the composition of the metal used for preparing the alloy powder was changed. The concentration of inevitable impurities in the alloy powder is as follows: P concentration is 0.008 wt%, Si concentration is 0.040 wt%, S concentration is 0.012 wt%, Sn concentration is 0.006 wt%, and Sb. The concentration was 0.002 wt%, the As concentration was 0.006 wt%, the Mn concentration was 0.300 wt%, the O concentration was 0.002 wt%, and the N concentration was 0.003 wt%.

  Next, nickel concentration distribution was analyzed about the manufactured alloy structure which concerns on Example 3-1 and Example 3-2. The analysis of the nickel concentration distribution was performed by arbitrarily extracting a total of 16 rectangular parallelepiped portions by a scanning electron microscope-energy dispersive X-ray detector (SEM-EDX) 10 This was done by measuring the nickel concentration in the area of the location. Table 2 shows the results of the average value and standard deviation of the Ni concentration distribution for a total of 16 rectangular parallelepiped parts.

  As shown in Table 2, in the alloy structure according to Example 3-1 in which inevitable impurities are further restricted, the deviation of the nickel concentration distribution for each rectangular parallelepiped part is larger than that in the alloy structure according to Example 3-2. A small tendency appears, and it can be seen that the uniformity of the elemental composition distribution of the alloy structure is enhanced by further limiting the inevitable impurities of the alloy powder.

  Next, test pieces were sampled along the stacking direction for a total of 16 rectangular parallelepiped portions of the alloy structure shown in FIG. 5 and subjected to a uniaxial compression test. For the test piece, a dumbbell-shaped test piece having a major axis in the stacking direction in the alloy structure is cut out from each rectangular parallelepiped part to a plate-like part, and the dimension of the parallel part is 4 mm in diameter and 30 mm in height. It was. The measurement result of the compression true stress-compression true strain diagram at room temperature is shown in FIG. 6 as an average of a total of 16 rectangular parallelepiped parts.

  6 is a compression true stress-compression true strain diagram in an alloy structure according to Example 3. FIG.

  As shown in FIG. 6, the variation of the true stress-true strain diagram is hardly recognized in any of Example 3-1 and Example 3-2, and the diagram of the line width shown in FIG. 6 can be drawn. did it. That is, it was confirmed that the uniformity of the mechanical characteristics was enhanced over the entire area of the shaped object in the alloy structure having a volume about 160 times larger than the alloy material shown in Non-Patent Document 2. In particular, in Example 3-2, the tensile strength is about 2800 MPa and the total elongation is about 38%, whereas in Example 3-1, the tensile strength is about 3850 MPa and the total elongation is about 43%. It can be seen that the strength is increased by about 1.37 times and the total elongation is increased by about 1.1 times. Therefore, it is recognized that the mechanical characteristics can be further improved by reducing the concentration of inevitable impurities.

  Next, as examples of the present invention, alloy structures according to Example 4-1 to Example 4-3 were manufactured, and tensile properties were evaluated.

[Example 4-1]
As Example 4-1, an alloy structure in which the elemental composition is expressed by AlCoCrFeNi and the concentration of inevitable impurities is limited is manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%. Further, the P concentration is 0.002 wt% or less, the Si concentration is 0.010 wt% or less, the S concentration is 0.001 wt% or less, the Sn concentration is 0.002 wt% or less, and the Sb concentration is 0.001 wt%. Hereinafter, the As concentration was limited to 0.001 wt% or less, the Mn concentration was 0.020 wt% or less, the O concentration was 0.0003 wt% or less, and the N concentration was 0.001 wt% or less.

  First, the atomic concentration of Al is about 7 at%, the atomic concentration of Co, Cr, Fe and Ni is about 23.3 at%, the concentration of P is 0.002 wt% or less, the concentration of Si is 0.010 wt% or less, S concentration is 0.001 wt% or less, Sn concentration is 0.002 wt% or less, Sb concentration is 0.001 wt% or less, As concentration is 0.001 wt% or less, Mn concentration is 0.020 wt% or less, An alloy powder was prepared by a gas atomization method using an alloy in which the concentration of O was limited to 0.0003 wt% or less and the concentration of N was limited to 0.001 wt% or less as a bare metal. The obtained alloy powder was classified so that the particle size distribution was limited to a range of 45 μm or more and 105 μm or less, and the volume-based average particle size was about 70 μm.

  Subsequently, an alloy structure was modeled on the base material using an additive manufacturing apparatus. As the substrate, a plate-like carbon steel for mechanical structure “S45C” of 200 mm × 200 mm × 10 mm was used. Further, as the additive manufacturing apparatus, an electron beam melt additive manufacturing apparatus “A2X” (manufactured by Arcam) using an electron beam as a heat source was used. In the additive manufacturing apparatus, a dumbbell-shaped test piece having the horizontal direction of the solidified layer as a horizontal axis is formed as an alloy structure by repeatedly performing a powder spreading process and a solidified layer forming process on a substrate in a vacuum atmosphere. did. At this time, the melting of the alloy powder was performed while preheating at a temperature of 50% to 80% of the melting point (Tm) of the alloy powder was performed in advance, and scattering of the spread alloy powder was suppressed. In addition, the dumbbell-shaped test piece was modeled in a state of being placed horizontally on the base material together with the support member that supports the test piece main body, and the dimensions of the parallel portion were 4 mm in diameter and 30 mm in height.

[Example 4-2]
As Example 4-2, an alloy structure whose element composition is expressed by AlCoCrFeNi and in which the concentration of inevitable impurities is limited was manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%. Further, the concentration of P is 0.002 wt% to 0.005 wt%, the concentration of Si is 0.010 wt% to 0.040 wt%, the concentration of S is 0.001 wt% to 0.002 wt%, and the concentration of Sn is 0.00. 002 wt% to 0.005 wt%, Sb concentration 0.001 wt% to 0.002 wt%, As concentration 0.001 wt% to 0.005 wt%, Mn concentration 0.020 wt% to 0.050 wt%, The O concentration was 0.0003 wt% to 0.001 wt%, and the N concentration was 0.001 wt% to 0.002 wt%.

  The alloy structure according to Example 4-2 was manufactured in the same manner as in Example 4-1, except that the composition of the metal used for preparing the alloy powder was changed.

[Example 4-3]
As Example 4-3, an alloy structure in which the elemental composition is expressed by AlCoCrFeNi and the concentration of inevitable impurities is not limited is manufactured by additive manufacturing. As for the atomic concentration ratio, the atomic concentration of Al, Co, Cr, Fe and Ni is about 20.0 at%.

  The alloy structure according to Example 4-3 was manufactured in the same manner as in Example 4-1, except that the composition of the metal used for preparing the alloy powder was changed. The concentration of inevitable impurities in the alloy powder is as follows: P concentration is 0.008 wt%, Si concentration is 0.040 wt%, S concentration is 0.012 wt%, Sn concentration is 0.006 wt%, and Sb. The concentration was 0.002 wt%, the As concentration was 0.006 wt%, the Mn concentration was 0.300 wt%, the O concentration was 0.002 wt%, and the N concentration was 0.003 wt%.

  Next, a tensile test was performed on the manufactured alloy structures according to Example 4-1 to Example 4-3. The tensile test was performed from 0 ° C. to 900 ° C., and the tensile strength was measured. The measurement result of the tensile test is shown in FIG.

  FIG. 7 is a diagram showing the test temperature dependence of the tensile strength in the alloy structure according to Example 4.

  As shown in FIG. 7, in the alloy structure according to Example 4-1 to Example 4-2 in which inevitable impurities are limited, the alloy structure according to Example 4-3 in which inevitable impurities are not limited. On the other hand, it can be seen that the tensile strength is improved. Moreover, in the alloy structure which concerns on Example 4-1 which restricted the inevitable impurity more, it turns out that the tensile strength is improving in a wide temperature range. Therefore, it was confirmed that it is effective to further improve the mechanical characteristics by reducing the concentration of inevitable impurities.

  Next, as examples of the present invention, the alloy structures according to Example 5, Example 6, Example 7, and Example 8 were manufactured by changing the element type of the main component, and evaluated.

  First, it was estimated by thermodynamic calculation whether or not a solid solution phase of a high entropy alloy can be formed with iron (Fe) and other plural elements as main components. The thermodynamic calculation is performed using the first principle calculation method assuming that five or more elements including Fe are contained in an element composition having an equiatomic ratio, and in such an element composition, It was confirmed whether a solid solution phase could be formed at normal temperature and normal pressure. In addition to Fe, a plurality of main elements were selected from element groups of atomic number 3 to atomic number 83 contained in groups 3 to 16 of the periodic table.

  FIG. 8 is a diagram showing a range of main component elements capable of forming a solid solution phase in the alloy structure.

  In FIG. 8, the vertical axis represents the atomic number of the element, and the horizontal axis represents the ratio of the atomic radius to the Fe atom (atomic radius of each element / atomic radius of Fe). Moreover, the shape of each plot shows the crystal structure at normal temperature and normal pressure. Double squares are face-centered cubic lattices, double circles are body-centered cubic lattices, hexagons are hexagonal close packed, and squares are other crystal lattices.

  As a result of thermodynamic calculations for various combinations of the main component elements, it is possible to form a solid solution phase for the elemental composition containing the elements in the region surrounded by the chain line in FIG. It turned out to be. Specifically, the element (non-Fe main component element) that was found to be soluble with Fe is the ratio of the atomic radius to the Fe atom among the atomic number 13 Al to the atomic number 79 Au. Elements having a value of 0.83 or more and 1.17 or less, that is, Al, Si, P, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Nb, Mo, Tc , Ru, Rh, Pd, Ag, Sn, Sb, Te, Ta, W, Re, Os, Ir, Pt, and Au. As the component composition according to the combination, CoCrFeNiAl, CoCrFeNiCu, CoCrFeNiCuAl, CoCrFeNiCuAlSi, MnCrFeNiCuAl, CoCrFeNiMnGe, CoCrFeNiMn, CoCrFeNiMnCu, TiCoCrFeNiCuAlV, TiCoCrFeNiAl, AlTiCoCrFeNiCuVMn, TiCrFeNiCuAl, TiCoCrFeNiCuAl, CoCrFeNiCuAlV, TiCoCrFeNiAl, TiCoCrFeNiCuAl, CoCrFeNiCuAl, CoFeNiCuV, CoCrFeNiCuAl, MnCrFeNiAl, MoCrFeNiCu, TiCoCrFeNi, TiCoCrFeNiMo, CoCrFeNiCuAlV, nCrFeNiCu, TiCoCrFeNi, TiCoCrFeNiAl, CoCrFeNiMo, CoCrFeNiAlMo, TiCoCrFeNiCu, CoCrFeNiCuAlMn, TiCoCrFeNiMo, CoCrFeNiCuAlV, TiCoCrFeNiCuVMn, AlTiCoCrFeNiCuVMn, CoCrFeNiCuAlMn, CoCrFeNiAlMo, CoCrFeNiCuAlMo, TiCoCrFeNiCu, etc. was confirmed. Among these, a 9-element high-entropy alloy of AlTiCoCrFeNiCuVMn was applied to modeling of the alloy structures according to Example 5, Example 6, Example 7, and Example 8.

[Example 5]
As Example 5, the alloy structure shown in FIG. 5 in which the elemental composition was AlTiCoCrFeNiCuVMn and the concentration of inevitable impurities was limited was manufactured by additive manufacturing. The atomic concentration ratios of Al, Ti, Co, Cr, Fe, Ni, Cu, V, and Mn were set to be approximately equiatomic ratios by making the difference in atomic concentration within a range of ± 3%. Further, the concentration of P is 0.005 wt% to 0.002 wt%, the concentration of Si is 0.040 wt% to 0.010 wt%, the concentration of S is 0.002 wt% to 0.001 wt%, and the concentration of Sn is 0.00. 005 wt% to 0.002 wt%, Sb concentration from 0.002 wt% to 0.001 wt%, As concentration from 0.005 wt% to 0.001 wt%, Mn concentration from 0.050 wt% to 0.020 wt%, The O concentration was limited to the range of 0.001 wt% to 0.0003 wt%, and the N concentration was limited to the range of 0.002 wt% to 0.001 wt%.

  First, the atomic concentrations of Al, Ti, Co, Cr, Fe, Ni, Cu, V, and Mn are substantially equiatomic ratios, the P concentration is 0.002 wt% or less, and the Si concentration is 0.010 wt% or less. The concentration of S is 0.001 wt% or less, the concentration of Sn is 0.002 wt% or less, the concentration of Sb is 0.001 wt% or less, the concentration of As is 0.001 wt% or less, and the concentration of Mn is 0.020 wt% or less. An alloy powder was prepared by a gas atomization method using an alloy in which the concentration of O was limited to 0.0003 wt% or less and the concentration of N was limited to 0.001 wt% or less as a bare metal. The obtained alloy powder was classified so that the particle size distribution was limited to a range of 45 μm or more and 105 μm or less, and the volume-based average particle size was about 70 μm.

Subsequently, an alloy material was modeled on the base material using an additive manufacturing apparatus. As the substrate, a plate-like carbon steel for mechanical structure “S45C” of 200 mm × 200 mm × 10 mm was used. Further, as the additive manufacturing apparatus, an electron beam melt additive manufacturing apparatus “A2X” (manufactured by Arcam) using an electron beam as a heat source was used. In the layered modeling apparatus, modeling was performed by repeatedly performing a powder spreading process and a solidified layer modeling process on a base material in a vacuum atmosphere. At this time, the melting of the alloy powder was performed while preheating at a temperature of 50% to 80% of the melting point (Tm) of the alloy powder was performed in advance, and scattering of the spread alloy powder was suppressed. The manufactured alloy structure according to Example 5 had substantially the same shape as the alloy structure shown in FIG. 5, and the volume of the entire modeled object was 856700 mm ³ .

  Next, test pieces were sampled along the stacking direction for a total of 16 rectangular parallelepiped portions of the alloy structure according to Example 5, and a uniaxial compression test was performed. For the test piece, a dumbbell-shaped test piece having a major axis in the stacking direction in the alloy structure is cut out from each rectangular parallelepiped part to a plate-like part, and the parallel part has a diameter of 8 mm × height of 12 mm. It was. Moreover, Fe concentration distribution was analyzed about the manufactured alloy structure based on Example 5. FIG. The analysis of the Fe concentration distribution was performed by measuring the iron concentration in 10 regions arbitrarily extracted by scanning electron microscope-energy dispersive X-ray spectroscopy for a total of 16 cuboid portions.

  As a result, it was confirmed that on average for each rectangular parallelepiped part, the variation in the true stress-true strain diagram and the Fe concentration distribution were both within the range of the difference of 1 to 3%. Moreover, the result that the standard deviation was 1.20% or less was obtained, and it was confirmed that the uniformity of the distribution of the element composition was improved. Further, the elemental composition of the alloy structure according to Example 5 is substantially the same as the elemental composition of the alloy powder used, and the error in the component concentration is within about ± 3%, and the elemental composition distribution, melting rate, cooling It was confirmed that the unevenness caused by the speed and the like was eliminated and the uniformity of the distribution of the element composition and the mechanical strength could be secured.

[Example 6]
As Example 6, an alloy structure (see FIG. 9) having an arc-shaped shape in which the elemental composition was AlTiCoCrFeNiCuVMn and the concentration of inevitable impurities was limited was manufactured by additive manufacturing.

  FIG. 9 is a diagram illustrating the shape dimensions of the alloy structure according to Example 6.

As shown in FIG. 9, the alloy structure 1 </ b> A according to Example 6 is a columnar body having a circular cross section, and has a shape applicable to a turbine blade or the like. An alloy structure 1A having such a shape is manufactured in the same manner as in Example 5 except that the three-dimensional shape to be layered is changed, and the width (W) 149 mm × depth (D) 110 mm × height ( H) Modeled as a 153 mm arc shaped model. The manufactured alloy structure according to Example 6 has a total volume of 184480 mm ³ and a surface area of 60470 mm ² , and is formed with a volume approximately 33 times that of the alloy material shown in Non-Patent Document 2. I was able to.

  Next, the Fe concentration distribution of the alloy structure according to Example 6 was analyzed. The analysis of the Fe concentration distribution was performed by measuring the iron concentration in 10 arbitrarily extracted regions by scanning electron microscope-energy dispersive X-ray spectroscopy.

  As a result, the elemental composition of the alloy structure according to Example 6 is substantially the same as the elemental composition of the alloy powder used, and the component concentration error is within about ± 3%, and the elemental composition distribution, melting rate, It was confirmed that the unevenness due to the cooling rate and the like was eliminated and the uniformity of the distribution of the element composition and the mechanical strength could be secured.

[Example 7]
As Example 7, an alloy structure having an element composition of AlTiCoCrFeNiCuVMn and a dumbbell-shaped shape in which the concentration of inevitable impurities was limited was manufactured by additive manufacturing.

  The alloy structure according to Example 7 was manufactured in the same manner as in Example 4-1, except that the composition of the bare metal used for the preparation of the alloy powder and the three-dimensional shape to be layered were changed, and solidified. It was set as the dumbbell-shaped shaped object which makes the lamination direction of a layer a horizontal axis.

  As a result, the elemental composition of the alloy structure according to Example 7 is substantially the same as the elemental composition of the alloy powder used, and the component concentration error is within about ± 3%, and the elemental composition distribution, melting rate, It was confirmed that the unevenness due to the cooling rate and the like was eliminated and the uniformity of the distribution of the element composition and the mechanical strength could be secured. Moreover, compared with the alloy structure which concerns on Example 4-1, it was confirmed that the surface became smooth and a metallic luster was strongly expressed, and surface properties were improved by diversifying the elemental composition of the alloy structure. It was found that the effect of reforming can be obtained.

[Example 8]
As Example 8, an alloy structure having an element composition of AlTiCoCrFeNiCuVMn and having a rod-like shape in which the concentration of inevitable impurities was limited was manufactured by additive manufacturing.

  The alloy structure according to Example 8 was modeled in the same manner as in Example 4-1, except that the composition of the metal used for preparing the alloy powder and the three-dimensional shape to be layered were changed.

  As a result, the elemental composition of the alloy structure according to Example 8 is substantially the same as the elemental composition of the used alloy powder, and the error of the component concentration is within about ± 3%, the elemental composition distribution, the melting rate, It was confirmed that the unevenness due to the cooling rate and the like was eliminated and the uniformity of the distribution of the element composition and the mechanical strength could be secured. Using the manufactured alloy structure according to Example 8 as a friction stir tool, a soft iron plate having a thickness of 10 mm or less was joined by friction stir welding. As a result, it was possible to perform bonding without causing defects in the bonded portion, and it was possible to perform good bonding with almost no warping. That is, the multi-component alloy structure according to Example 8 was required to have high-temperature strength and wear resistance, and was confirmed to be applicable to friction stir welding of Fe-based materials, which was difficult in the past. It was. In addition, in a solidified layer forming process, in a high temperature state until the solidified portion is formed, by performing shape forming processing or surface processing of the solidified portion or the solidified layer, a molded object that has been appropriately processed is obtained. It was also confirmed that

DESCRIPTION OF SYMBOLS 1 Alloy structure 10 Alloy powder 15 Base material 20 Melting part 21 Base material mounting base 22 Processing table 23 Recoater 24 Heating means 30 Solidification part 40 Solidified layer 50 Crystal grain 100 Melting boundary 110 Grain boundary (Large angle grain boundary)
120 Low-angle grain boundary 301 Electric furnace 302 Metal lump 303 Arc discharge 304 Electrode 305 Oxygen burner 306 Oxygen gas 309 Ladle 310 Molten metal 311 Ladle smelting furnace 313 Porous plug 314 Argon gas 316 Vacuum device 317 Exhaust hole 318 Tundish 319 Vacuum Vessel 320 Exhaust hole 324 Electric furnace 326 Molten alloy 330 Chamber

Claims (7)

A melting step of melting a raw metal mass to produce a molten metal;
A peroxidation step of forming slag by blowing oxygen gas into the molten metal;
A separation step of separating the slag from the molten metal and the molten metal;
A degassing step of degassing a gas component in the molten metal by blowing argon gas into the molten metal separated from the slag;
A casting step of casting the degassed molten metal to form a cast alloy;
Melting the cast alloy in vacuum to form a molten alloy;
In a method for producing an alloy powder comprising: flowing the molten alloy; and pulverizing an inert gas to the molten alloy that flows down to form an alloy powder.
The alloy powder is selected from an element group of atomic number 13 to atomic number 79 included in groups 3 to 16 of the periodic table except for P, Si, Sn, Sb, As, and Mn , Fe atoms Containing at least four elements with a ratio of atomic radius to 0.83 or more and 1.17 or less, and five elements of Fe,
Each of the five elements is contained in an atomic concentration range of 5 at% to 30 at%,
As inevitable impurities, P is 0.005 wt% or less, Si is 0.040 wt% or less, S is 0.002 wt% or less, Sn is 0.005 wt% or less, Sb is 0.002 wt% or less, and As is 0.005 wt%. %, Mn is 0.050 wt% or less, O is 0.001 wt% or less, and N is contained in an atomic concentration range of 0.002 wt% or less.   As the inevitable impurities, P is 0.002 wt% or more and 0.005 wt% or less, Si is 0.010 wt% or more and 0.040 wt% or less, S is 0.001 wt% or more and 0.002 wt% or less, and Sn is 0.002 wt%. % To 0.005 wt%, Sb from 0.001 wt% to 0.002 wt%, As from 0.001 wt% to 0.005 wt%, Mn from 0.020 wt% to 0.050 wt%, and O to 0 2. The method for producing an alloy powder according to claim 1, comprising: .0003 wt% or more and 0.001 wt% or less and N in an atomic concentration range of 0.001 wt% or more and 0.002 wt% or less.   As the inevitable impurities, P is 0.002 wt% or less, Si is 0.005 wt% or less, S is 0.001 wt% or less, Sn is 0.002 wt% or less, Sb is 0.001 wt% or less, and As is 0.00. The alloy powder production according to claim 1, comprising 001 wt% or less, Mn 0.005 wt% or less, O 0.0003 wt% or less, and N in an atomic concentration range of 0.001 wt% or less. Method. The at least four elements are Al, Ti , V, Cr, Co , Ni, Cu, Zn, Ga, Ge , Se, Nb, Mo, Tc, Ru, Rh, Pd, Ag , Te, The method for producing an alloy powder according to claim 1, wherein the alloy powder is selected from the group consisting of Ta, W, Re, Os, Ir, Pt, and Au. In the powdering step, the alloy is melted in a vacuum furnace, and the materials constituting the vacuum furnace are SiO ₂ , graphite, Al ₂ O ₃ , MgO, ZrO ₂ , TiC, ZrC, HfC, NbC, TaC. The method for producing an alloy powder according to claim 1, comprising at least one kind. 2. The method for producing an alloy powder according to claim 1 , wherein the alloy has a difference in atomic concentration of at least four of the five elements within a range of less than 3 at%.   The alloy contains at least four elements of Al, Co, Cr, Fe, and Ni in an atomic concentration range of 15 at% to 23.75 at%, and contains the other one element at 5 at%. The method for producing an alloy powder according to claim 1, wherein the alloy powder is contained in an atomic concentration range of 30 at% or less.