JP2018145456A - Alloy member, manufacturing method of the alloy member and manufactured article using the alloy member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy member excellent in homogeneity of alloy composition and fine structure, excellent in shape control property, by using a high entropy alloy with high mechanical strength and high corrosion resistance.SOLUTION: The alloy member has a chemical composition consisting of each element of Co, Cr, Fe, Ni in a range of 5 atom% to 35 atom% respectively, Ti and Al in a range of 1 atom% to 10 atom% respectively, Mo in a range of 5 atom%, and the balance inevitable impurities, and having a deposit phase of face-centered cubic crystal having at least average particle diameter of 500 nm or less dispersed in a crystal of a parent phase.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an alloy member produced by a powder additive manufacturing method using a high-entropy alloy, a method for producing the alloy member, and a product using the alloy member.

  In recent years, high-entropy alloys (High Entropy Alloys) have been developed as alloys with a new technical concept that is completely different from the technical concept of conventional alloys (for example, alloys obtained by adding a small amount of multiple subcomponent elements to one to three main component elements). Entropy Alloy (HEA) has been proposed. HEA is defined as an alloy composed of four or more kinds of main metal elements (each 5 to 35 atomic%), and is known to exhibit the following characteristics.

  (A) Stabilization of the mixed state due to negative increase of the mixing entropy term in Gibbs free energy equation, (b) Diffusion delay due to complex fine structure, (c) High due to size difference of constituent atoms Increased hardness due to lattice distortion, reduced temperature dependence of mechanical properties, and (d) improved corrosion resistance due to combined effects (also called cocktail effect) due to coexistence of multiple elements.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-173732) discloses a high-entropy multicomponent alloy obtained by casting or synthesizing a plurality of types of metal elements, the alloy containing 5 to 11 types of main metal elements, A high-entropy multicomponent alloy is disclosed in which the number of moles of one main metal element is 5% to 30% of the total number of moles of the alloy. Further, it is described that the main metal element is selected from a metal element group including aluminum, titanium, vanadium, chromium, iron, cobalt, nickel, copper, zirconium, molybdenum, palladium, and silver.

  According to Patent Document 1, it is said that a high entropy multi-component alloy having higher hardness, higher heat resistance and higher corrosion resistance than conventional carbon steel and alloy carbon steel can be provided in a cast state.

JP 2002-173732 A

  However, the present inventors conducted various studies on HEA, and as a result, HEA is prone to element segregation and texture spots during casting due to the complexity of the alloy composition, and it is difficult to obtain a homogeneous ingot. It was. Element segregation and texture spots in alloy members are problems to be solved because they lead to variations in characteristics depending on the part.

  In addition, HEA has high hardness and resistance to tempering softening, so that it is difficult to process, and there is a problem that it is difficult to produce a desired shape member by machining. This is a major obstacle to commercialization and commercialization of HEA members, and a problem to be solved.

  On the other hand, as mentioned above, HEA has attractive features that cannot be obtained with conventional alloys. Therefore, HEA members with excellent alloy composition / microstructure homogeneity and shape controllability, and their manufacture There is a strong need for method development.

  Accordingly, the object of the present invention is to use a high-entropy alloy (HEA) having high mechanical strength and high corrosion resistance to satisfy the above requirements, and is excellent in alloy composition / microstructure homogeneity and in shape controllability. An alloy member, a manufacturing method thereof, and a product using the alloy member.

(I) One aspect of the present invention is an alloy member using a high-entropy alloy,
Co (cobalt), Cr (chromium), Fe (iron), Ni (nickel) each in the range of 5 atomic percent to 35 atomic percent, Ti (titanium) and Al (aluminum) 1 atom each In a range of not less than 10% and not more than 10 atom%, and Mo (molybdenum) in a range of not more than 5 atom%, with the balance being inevitable impurities,
Provided is an alloy member characterized in that a face-centered cubic (FCC) precipitation phase having an average particle size of 500 nm or less is dispersed in a matrix phase crystal.

(II) Another aspect of the present invention is a method for producing the above alloy member,
A raw material mixing and melting step of mixing and melting the raw materials of the alloy to form a molten metal;
An atomizing step of forming alloy powder from the molten metal;
There is provided a manufacturing method of an alloy member, characterized by including an additive manufacturing process for forming an alloy additive manufacturing body having a desired shape by a metal powder additive manufacturing method using the alloy powder.

(III) Still another embodiment of the present invention is a product using the above alloy member,
Provided is a product using an alloy member, wherein the product is an impeller of a fluid machine.

  According to the present invention, a high-entropy alloy having high mechanical strength and high corrosion resistance, an alloy member excellent in alloy composition / microstructure homogeneity and excellent in shape controllability, a manufacturing method thereof, and the alloy member A product using can be provided.

It is process drawing which shows an example of the manufacturing method of the alloy member which concerns on this invention. It is a cross-sectional schematic diagram which shows the structure of the powder additive manufacturing apparatus of an electron beam melting method, and the example of an additive manufacturing method. It is a scanning electron microscope (SEM) observation image which shows the example of a fine structure of the longitudinal section of an alloy lamination fabrication object in the present invention. It is a SEM observation image which shows the example of a fine structure of the cross section of the alloy lamination fabrication object in the present invention. It is a transmission electron microscope (TEM) observation result which shows an example of the fine structure of the alloy lamination modeling body in this invention, (a) The bright field image containing a precipitation phase, (b) The electron obtained from the precipitation phase in a (C) An electron diffraction pattern obtained from the parent phase in (a). It is an element mapping image by a high angle scattering annular dark field scanning transmission electron microscope image (HAADF-STEM image) and STEM-EDX (energy dispersive X-ray spectroscopic analyzer) around the precipitation phase in the alloy laminate model according to the present invention. . It is an example of the product using the alloy member which concerns on this invention, and is a photograph which shows the impeller of a fluid machine. It is a cross-sectional schematic diagram which is another example of the product using the alloy member which concerns on this invention, and shows the centrifugal compressor incorporating the impeller of this invention. It is an example of the microstructure of the alloy member by hot forging, and is an SEM observation image showing the microstructure of FM-2.

The present invention can add the following improvements and changes to the above-described alloy member (I).
(I) The structure of the parent phase is a local rapidly solidified structure in which columnar crystals having an average particle size of 100 μm or less are grown.
(Ii) The precipitated phase is a crystalline particle in which the Ni component, the Ti component, and the Al component are concentrated more than the crystals of the parent phase.
(Iii) The chemical composition is such that the Co is 20 atomic% to 30 atomic%, the Cr is 10 atomic% to 25 atomic%, the Fe is 10 atomic% to 25 atomic%, and the Ni is 20 atomic% to 30 atomic%, Ti includes 2 atomic% to 10 atomic%, Al includes 2 atomic% to 10 atomic%, and the balance consists of the inevitable impurities.
(Iv) The chemical composition includes 25 to 30 atomic percent of Co, 15 to 23 atomic percent of Cr, 15 to 23 atomic percent of Fe, Ni 25 atomic% to 30 atomic%, Ti is 1 atomic% to 5 atomic%, Al is 1 atomic% to 10 atomic%, Mo is 1 atomic% to 3 atomic%, The balance consists of the inevitable impurities.
(V) Tensile strength is 1000 MPa or more and elongation at break is 5% or more.
(Vi) The crystal structure of the matrix is simple cubic (SC).

The present invention can be improved or changed as follows in the product (III) using the above-described alloy member.
(Vii) The product is a centrifugal compressor incorporating the impeller.

(Basic idea of the present invention)
As described above, high-entropy alloys (HEA) have attractive characteristics (such as high hardness and temper softening resistance) that cannot be obtained with conventional alloys, but they are difficult to process and have the desired shape. There was a problem that it was difficult to produce a member.

  The present inventors conducted extensive research on alloy compositions and shape control methods in order to develop HEA members having excellent shape controllability and ductility without sacrificing the characteristics of HEA. As a result, a normal cast HEA as disclosed in Patent Document 1 is formed by forming an alloy layered structure by a metal powder layered manufacturing method using a Co—Cr—Fe—Ni—Ti—Al— (Mo) alloy powder. The possibility of obtaining HEA members with better shape controllability and ductility than materials was found.

  Hereinafter, an embodiment of the present invention will be described along a manufacturing procedure of an alloy member with reference to the drawings. However, the present invention is not limited to the embodiments described here, and can be appropriately combined with or improved based on known techniques without departing from the technical idea of the invention. It is.

[Method for producing alloy member]
FIG. 1 is a process diagram showing an example of a method for producing an alloy member according to the present invention. As shown in FIG. 1, the manufacturing method of this invention has a raw material mixing melt | dissolution process, an atomization process, an additive manufacturing process, and an extraction process. Hereinafter, embodiments of the present invention will be described more specifically.

(Raw material mixing and dissolution process)
First, a raw material mixing and dissolving step is performed in which raw materials are mixed and dissolved to form a molten metal 10 so as to have a desired HEA composition (Co—Cr—Fe—Ni—Ti—Al— (Mo)). There are no particular limitations on the method of mixing and melting the raw materials, and conventional methods in the production of high strength and high corrosion resistance alloys can be used. For example, vacuum melting can be suitably used as a melting method. Further, it is preferable to refine the molten metal 10 together with a vacuum carbon deoxidation method or the like.

  The HEA composition of the present invention contains 4 elements of Co, Cr, Fe, and Ni as main components in the range of 5 atomic% to 35 atomic%, respectively, and Ti and Al are 1 atomic% to 10 atomic%, respectively. In the range, Mo is included in the range of 5 atomic% or less, and the balance is made of inevitable impurities.

  More specifically, Co is 20 atomic% to 30 atomic%, Cr is 10 atomic% to 25 atomic%, Fe is 10 atomic% to 25 atomic%, and Ni is 20 atomic% to 30 atomic%. It is more preferable that Ti is 2 atomic% or more and 10 atomic% or less, and Al is 2 atomic% or more and 10 atomic% or less. By controlling to these composition ranges, it is possible to achieve both improvement in ductility and improvement in mechanical strength. In other words, when each component is out of its preferred composition range, it is difficult to achieve desirable characteristics.

  In addition, when priority is given to improving corrosion resistance, it is preferable to add Mo, Co is 25 atomic% to 30 atomic%, Cr is 15 atomic% to 23 atomic%, and Fe is 15 atomic% to 23 atomic%. Atomic% or less, Ni is 25 atomic% or more and 30 atomic% or less, Ti is 1 atomic% or more and 5 atomic% or less, Al is 1 atomic% or more and 10 atomic% or less, and Mo is 1 atomic% or more and 3 atoms or less. % Or less is more preferable.

  In the present invention, an inevitable impurity is a component that is difficult to eliminate completely, but is defined as a component that is contained to such an extent that no particular adverse effect is exerted on various characteristics. Examples thereof include O (oxygen), N (nitrogen), and C (carbon).

(Atomizing process)
Next, an atomizing process for forming the alloy powder 20 from the molten metal 10 is performed. There is no particular limitation on the atomizing method, and a conventional method can be used. For example, a gas atomization method or a centrifugal atomization method that can obtain high-purity, homogeneous composition, and spherical particles can be preferably used.

  The average particle size of the alloy powder 20 is preferably 10 μm or more and 500 μm or less, more preferably 20 μm or more and 200 μm or less, from the viewpoints of handling properties and filling properties. When the average particle size is less than 10 μm, the alloy powder 20 is likely to rise in the subsequent layered manufacturing process, which causes a decrease in the shape accuracy of the alloy layered body. On the other hand, when the average particle size exceeds 500 μm, it becomes a factor that the surface roughness of the alloy layered structure is increased or the melting of the alloy powder 20 becomes insufficient in the next layered manufacturing process.

(Laminated modeling process)
Next, an additive manufacturing process for forming an alloy additive manufacturing body 230 having a desired shape is performed by a metal powder additive manufacturing method using the alloy powder 20 prepared above. By applying a metal powder additive manufacturing method that forms a near net shape metal member by melting and solidification instead of sintering, a mechanical strength equal to or higher than that of a cast material can be obtained, and a three-dimensional member having a complicated shape can be produced. be able to. The additive manufacturing method is not particularly limited, and a conventional method can be used. For example, a metal powder additive manufacturing method using an electron beam melting (EBM) method or a selective laser melting (SLM) method can be suitably used.

  The additive manufacturing process will be described using the EBM method as an example. FIG. 2 is a schematic cross-sectional view showing an example of a structure of an EBM method powder additive manufacturing apparatus and an additive manufacturing method. As shown in FIG. 2, the EBM powder additive manufacturing apparatus 100 is roughly divided into an electron beam control unit 110 and a powder control unit 120, and the whole is a vacuum chamber.

  1) The stage 121 is lowered by the thickness of one layer (for example, about 30 to 200 μm) of the alloy laminate model 230 to be modeled. The alloy powder 20 is supplied from the powder hopper 123 onto the base plate 122 on the upper surface of the stage 121, and the alloy powder 20 is flattened by the rake arm 124 to form a powder bed 210 (layered powder) (powder bed forming step).

  2) Thermoelectrons are emitted from the heated tungsten filament 111 (for example, 2500 ° C. or higher) and accelerated by the anode 112 (for example, about half the speed of light) to form an electron beam 113. The accelerated electron beam 113 is rounded by the astigmatism correction device 114 and focused on the powder bed 210 by the focus coil 115.

  3) A relatively weak (loose) focused beam is scanned by the deflection coil 116 to preheat the entire powder bed 210 to form a pre-sintered powder bed. In the EBM method, it is preferable to perform a step of forming a pre-sintered powder bed (powder bed calcining step) before locally melting and solidifying the powder bed. This is to prevent scattering of the powder bed due to charging of the alloy powder by irradiation with a focused beam for local melting. In addition, there is an additional effect that the deformation of the alloy laminate model 230 is suppressed by the heating in this step.

  The calcining temperature of the powder bed 210 is preferably 750 ° C. or higher and 1200 ° C. or lower. When the calcining temperature is less than 750 ° C., the sintering of the alloy powder particles hardly proceeds, and it becomes difficult to form a calcined body. On the other hand, when the calcining temperature exceeds 1200 ° C., the sintering of the alloy powders proceeds excessively, and it is difficult to take out the alloy laminate model 230 (separation between the alloy laminate model 230 and the provisional sintered product). .

  4) Based on the 2D slice data converted from the 3D-CAD data of the alloy layered object 230 to be shaped, the presintered body of the powder bed is irradiated with a strong focused beam for local melting and alloyed In addition, a 2D slice-shaped solidified layer 220 is formed by scanning the focused beam and moving and sequentially solidifying the fine molten pool (local melting / solidified layer forming step).

  5) The above-described 1) to 4) are repeated to form an alloy laminate model 230 having a desired shape.

(Removal process)
Since the alloy layered product 230 formed in the above process is buried in the temporary sintered body, an extraction step of taking out the alloy layered model 230 is performed next. There is no particular limitation on the method for taking out the alloy laminate model 230 (the separation method between the alloy laminate model 230 and the temporary sintered body, the separation method between the alloy laminate model 230 and the base plate 122), and the conventional method can be used. . For example, sand blasting using the alloy powder 20 can be preferably used. Sandblasting using the alloy powder 20 has an advantage that it can be reused as the alloy powder 20 by crushing together with the alloy powder 20 sprayed with the removed pre-sintered body.

[Alloy members]
After the extraction step, a sample for observing the microstructure was collected from the alloy laminate model 230, and the microstructure of the sample was observed using a scanning electron microscope (SEM). FIG. 3A is an SEM observation image showing an example of a microstructure of a longitudinal section (a surface along the stacking direction, a surface having a normal line perpendicular to the stacking direction) of the alloy laminate model according to the present invention, and FIG. It is a SEM observation image which shows the example of the fine structure of the cross section (surface perpendicular | vertical to a lamination direction, surface where a lamination direction becomes a normal line) of an alloy lamination modeling body.

  As shown in FIGS. 3A to 3B, the parent phase of the alloy laminate model 230 has a structure in which fine columnar crystals (average particle size of 100 μm or less) are forested along the lamination direction of the alloy laminate model 230 (so-called It is confirmed that it has a rapidly solidified structure. In the present invention, the crystal grain size of columnar crystals is defined as the length of the columnar minor axis direction (perpendicular to the stacking direction).

  Furthermore, in order to investigate the microstructure of the alloy laminate model 230 in more detail, a transmission electron microscope (TEM) and a scanning transmission electron microscope-energy dispersive X-ray spectrometer (STEM-EDX) Tissue observation was performed. As a result, it was observed that in the alloy laminate model 230, the precipitated phase of dice-like FCC (face-centered cubic) having an average particle diameter of 500 nm or less was dispersed in the parent phase crystal.

  FIG. 4 is a TEM observation result showing an example of a microstructure of an alloy laminate model according to the present invention, (a) a bright-field image including a precipitated phase, and (b) an electron beam diffraction obtained from the precipitated phase in a. Pattern (c) Electron diffraction pattern obtained from the parent phase in a. The intensity of the satellite spot in the electron beam diffraction pattern shown in FIG. 4B is increased as compared with the electron beam diffraction pattern of the matrix (matrix) shown in FIG. The satellite spot (b) is considered to be caused by fine precipitates, and the fine precipitates are considered to be aligned with the matrix.

  Further, the crystal structure of the precipitated phase was identified as FCC (a≈0.359 nm) by indexing the satellite spots in FIG. The crystal structure of the matrix was identified as simple cubic (SC, a≈0.358 nm) by indexing the main spot derived from the matrix in FIG.

  FIG. 5 is a high-angle scattering annular dark-field scanning transmission electron microscope image (HAADF-STEM image) and an element mapping image by STEM-EDX in the vicinity of the precipitation phase in the alloy laminate model according to the present invention. In each element mapping image, the closer to white, the higher the atomic concentration, and the closer to black, the lower the atomic concentration.

  As shown in FIG. 5, in addition to a dice-like precipitation phase having a particle size of about 200 to 300 nm in which Ni, Ti, and Al are concentrated, an extremely fine precipitation phase in which Ni and Ti are concentrated is also present. It was confirmed to exist. The crystal structure of the ultrafine precipitate phase was identified as the same FCC (a≈0.359 nm) as the dice-like precipitate phase by indexing the electron diffraction pattern of TEM.

[Products using alloy members]
FIG. 6 is a photograph showing an impeller of a fluid machine, which is an example of a product using an alloy member according to the present invention. Since the alloy product of the present invention is manufactured by the metal powder additive manufacturing method, even a complex shape as shown in FIG. 6 can be easily modeled. Moreover, since the impeller using the alloy member of the present invention has both high mechanical properties and high corrosion resistance, it can exhibit excellent durability even under severe stress / corrosion environments.

  FIG. 7 is a schematic cross-sectional view showing a centrifugal compressor in which the impeller of the present invention is incorporated, which is another example of a product using the alloy member according to the present invention. By using the impeller of the present invention exhibiting excellent durability even under severe stress / corrosion environment, it is possible to contribute to improvement of long-term reliability of the centrifugal compressor.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

[Experiment 1]
(Preparation of HEA powder P-1 to P-6)
The raw materials were mixed with the nominal composition shown in Table 1, and the raw material mixing and dissolving step was performed in which the molten metal was formed by melting by a vacuum melting method. Next, the atomization process which forms alloy powder from a molten metal was performed by the gas atomization method. Next, the obtained alloy powder was classified by sieving to select a particle size of 45 to 105 μm to prepare HEA powders P-1 to P-6. When the particle size distribution of P-1 to P-6 was measured using a laser diffraction particle size distribution analyzer, the average particle size of each was about 70 μm.

[Experiment 2]
(Production of alloy members AM-1 to AM-6 by additive manufacturing)
For the HEA powders P-1 to P-6 prepared in Experiment 1, using a powder additive manufacturing apparatus (Arcam AB, model: A2X) as shown in FIG. An alloy layered body (14 mm diameter x 85 mm height, height direction is the stacking direction) was modeled by the EBM method. The calcining temperature of the powder bed was 850 to 980 ° C.

  After the additive manufacturing process, the temporary sintering body around the alloy additive manufacturing body was removed by sand blasting using HEA powder to take out alloy members AM-1 to AM-6 by additive manufacturing.

[Experiment 3]
(Preparation of alloy members FM-1 to FM-6 by hot forging)
For the HEA powders P-1 to P-6 prepared in Experiment 1, cast material (square column material 14 mm wide x 80 mm long x 15 mm high) is produced by arc melting using a copper water-cooled mold. Prepared. Next, the casting material is heated twice in the air (held at 1160 ° C. for 15 minutes) and then subjected to a hot forging process in which press working (rolling rate: 30%, rolling speed: 30 mm / s) is performed twice. Repeatedly, a hot forging was prepared.

  Furthermore, for the hot forged material, solution treatment (water cooling after holding at 1170 ° C. in the air for 3 hours), and aging treatment (maintaining at 980 ° C. for 15 hours in the air) simulating the calcination process of EBM, Thus, alloy members FM-1 to FM-6 were produced by hot forging. These alloy members obtained by hot forging are samples that have not been subjected to the additive manufacturing process, and serve as reference samples for confirming the effects of the metal powder additive manufacturing.

[Experiment 4]
(Microstructure observation of alloy members)
A specimen for microstructural observation was collected from each of the alloy members produced above, and microstructural observation was performed using various electron microscopes (SEM, STEM-EDX) and an X-ray diffraction (XRD) apparatus. Table 2, FIG. 8, FIG. 3A to FIG. 3B show the microstructure observation results together with the production specifications of each alloy member.

  FIG. 8 is an example of the microstructure of the alloy member by hot forging, and is an SEM observation image showing the microstructure of FM-2. FIG. 3A to FIG. 3B described above are SEM observation images showing the microstructure of the alloy member AM-2 by additive manufacturing.

As shown in Table 2 and FIG. 8, in the alloy members FM-1 to FM-6 by hot forging, the parent phase structure has a structure composed of equiaxed crystals (so-called forged structure), and the average particle diameter Was about 400 μm. As a result of XRD measurement and STEM observation, the crystal structure of the equiaxed crystal was almost regarded as consisting of simple cubic crystals (SC). The precipitates in FM-1 to FM-6 were Ni ₃ (Ti, Al) phases having an FCC crystal structure. However, the dispersion form of the precipitate was dispersed and precipitated unevenly.

On the other hand, as shown in Table 2 and FIGS. 3A to 3B, in the alloy members AM-1 to AM-6 by the layered modeling, fine columnar crystals (average particle size of 100 μm or less) are stacked in the layered molded body stacking direction. It had a forest (so-called rapidly solidified tissue) that was forested along the line. As a result of XRD measurement and STEM observation, the crystal structure of the columnar crystal was almost regarded as being composed of SC. Further, the precipitates at AM-1 to AM-6 were observed to be Ni ₃ (Ti, Al) phases having an FCC crystal structure and dispersed and precipitated almost uniformly.

[Experiment 5]
(Measurement of mechanical properties and corrosion resistance of alloy members)
A specimen for a tensile test (parallel part diameter: 4 mm, parallel part length: 20 mm) was collected from each alloy member produced above. In addition, the alloy member by lamination modeling was extract | collected so that a test piece longitudinal direction might correspond with a lamination modeling direction.

Each specimen was subjected to a room temperature tensile test using a universal material testing machine (based on JIS Z 2241, strain rate: 5 × 10 ⁻⁵ s ⁻¹ ), and the tensile strength and elongation at break were measured. The measurement result of the tensile test was obtained as an average value of 8 measurements excluding the maximum value and the minimum value of 10 measurements. In the evaluation of tensile strength, 1000 MPa or more was judged as “pass”, and less than 1000 MPa was judged as “fail”. In addition, the evaluation of elongation at break was 5% or more as “pass” and less than 5% as “fail”. The results are shown in Table 3 below.

In addition, polarization test pieces (15 mm long × 15 mm wide × 2 mm thick) for pitting corrosion tests were collected from each of the alloy members produced above. The pitting corrosion test was performed on each polarization test piece in accordance with JIS G 0577. Specifically, “Test area: 1 cm ² , crevice corrosion prevention electrode is attached to polarization test piece, reference electrode: saturated silver chloride electrode, test solution: 3.5% sodium chloride aqueous solution degassed with argon gas, test temperature: The anodic polarization curve of the polarization test piece was measured under the conditions of “80 ° C., potential sweep rate: 20 mV / min” to determine the pitting corrosion occurrence potential corresponding to a current density of 100 μA / cm ² . In the evaluation of the pitting corrosion occurrence potential, 0.50 V or more was determined as “pass”, and less than 0.50 V was determined as “fail”. The results of the pitting corrosion test are also shown in Table 3.

  As shown in Table 3, the alloy members FM-1 to FM-6 by hot forging, which are samples not subjected to the additive manufacturing process, have a tensile strength of less than 1000 MPa and an elongation at break of less than 5%. The mechanical properties were unacceptable. On the other hand, the alloy members AM-1 to AM-6 formed by additive manufacturing had a tensile strength of 1000 MPa or more and an elongation at break of 5% or more.

  Regarding the corrosion resistance, in the alloy members using HEA powders P-1 to P-3, a difference was observed between the alloy members by hot forging and the alloy members by additive manufacturing. Specifically, the alloy members FM-1 to FM-3 by hot forging failed the corrosion resistance evaluation, whereas the alloy members AM-1 to AM-3 by additive manufacturing using the same powder were The corrosion resistance evaluation was acceptable. From this result, it was confirmed that the alloy member according to the present invention has excellent corrosion resistance.

  Moreover, the alloy members (FM-4 to FM-6, AM-4 to AM-6) using HEA powders P-4 to P-6 containing Mo component all had good corrosion resistance. From this result, it was confirmed that the alloy member according to the present invention exhibits excellent corrosion resistance by the combination of elements itself (Co—Cr—Fe—Ni—Ti—Al—Mo).

[Experiment 6]
(Production and inspection of products using alloy members)
The impeller shown in FIG. 7 was produced by the same procedure as the manufacturing method of alloy member AM-2 by additive manufacturing. The obtained impeller was subjected to internal defect inspection by X-ray CT scan and dimension measurement. As a result, no internal defects that adversely affect the mechanical properties were observed, and no deformation with respect to the design dimensions was observed. From this experiment, the effectiveness of the present invention was confirmed.

  The above-described embodiments and examples are described in order to facilitate understanding of the present invention, and the present invention is not limited to the specific configurations described. For example, it is possible to replace a part of the configuration of the embodiment with the configuration of common technical knowledge of those skilled in the art, and it is also possible to add the configuration of technical common sense of those skilled in the art to the configuration of the embodiment. That is, according to the present invention, a part of the configurations of the embodiments and examples of the present specification may be deleted, replaced with other configurations, and added with other configurations without departing from the technical idea of the invention. Is possible.

10 ... molten metal, 20 ... alloy powder,
100 ... EBM powder additive manufacturing equipment, 110 ... electron beam control unit, 120 ... powder control unit,
111 ... tungsten filament, 112 ... anod, 113 ... electron beam,
114 ... Astigmatism correction device, 115 ... Focus coil, 116 ... Deflection coil,
121 ... Stage, 122 ... Base plate, 123 ... Powder hopper,
124 ... Rake arm,
210 ... powder bed, 220 ... solidified layer, 230 ... alloy laminate model.

Claims (10)

An alloy member,
Each element of Co, Cr, Fe, and Ni is included in the range of 5 atomic% to 35 atomic%, Ti and Al are included in the range of 1 atomic% to 10 atomic%, respectively, and Mo is 5 atomic% or less. In the range, the remainder has a chemical composition consisting of inevitable impurities,
An alloy member characterized in that a face-centered cubic precipitated phase having an average grain size of 500 nm or less is dispersed in a matrix phase crystal. The alloy member according to claim 1,
2. The alloy member according to claim 1, wherein the microstructure of the matrix is a rapidly solidified structure in which columnar crystals having an average particle diameter of 100 μm or less are formed. In the alloy member according to claim 1 or 2,
The alloy phase, wherein the precipitation phase is a crystalline particle in which the Ni component, the Ti component, and the Al component are concentrated more than the crystal of the parent phase. In the alloy member according to any one of claims 1 to 3,
The chemical composition includes 20 to 30 atomic percent of Co, 10 to 25 atomic percent of Cr, 10 to 25 atomic percent of Fe, and 20 atomic percent of Ni. An alloy member characterized by comprising 30 atomic% or less, Ti containing 2 atomic% or more and 10 atomic% or less, Al containing 2 atomic% or more and 10 atomic% or less, and the balance comprising the inevitable impurities. In the alloy member according to any one of claims 1 to 3,
The chemical composition includes 25 to 30 atomic percent of Co, 15 to 23 atomic percent of Cr, 15 to 23 atomic percent of Fe, and 25 atomic percent of Ni. 30 atomic% or less, Ti is 1 atomic% or more and 5 atomic% or less, Al is 1 atomic% or more and 10 atomic% or less, Mo is 1 atomic% or more and 3 atomic% or less, and the balance is the above An alloy member comprising inevitable impurities. In the alloy member according to any one of claims 1 to 5,
An alloy member having a tensile strength of 1000 MPa or more and an elongation at break of 5% or more. In the alloy member according to any one of claims 1 to 6,
An alloy member, wherein the crystal structure of the matrix is a simple cubic crystal. A method for producing an alloy member according to any one of claims 1 to 7,
A raw material mixing and melting step of mixing and melting the raw materials of the alloy to form a molten metal;
An atomizing step of forming alloy powder from the molten metal;
The manufacturing method of the alloy member characterized by the additive manufacturing process which forms the alloy additive manufacturing body which has a desired shape by the metal powder additive manufacturing method using the said alloy powder. A product using an alloy member,
The alloy member is an alloy member according to any one of claims 1 to 8,
A product using an alloy member, wherein the product is an impeller of a fluid machine.   A centrifugal compressor incorporating the impeller according to claim 9.

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