Nickel-based alloy powder for laminated molding, laminated molded products using the nickel-based alloy powder, and methods for manufacturing the same.

Abstract

This invention provides a nickel-based alloy powder suitable for lamination molding that is free of cracks or defects and has excellent high-temperature oxidation resistance, as well as a laminated product using the nickel-based alloy powder and a method for manufacturing the same. The solution is a nickel-based alloy powder for lamination molding, characterized in that it contains, by mass%, Al: 3.5%–5.5%, Cr: 0.8%–4.0%, C: 0.02%–0.06%, Si: 1.0%–3.0%, Mn: less than 1.5%, O: 0.001%–0.050%, with the remainder containing Ni and unavoidable impurities, wherein the Zr content in the unavoidable impurities is limited to less than 0.01%.

Description

Technical Field

[0001] This invention relates to a nickel-based alloy powder (hereinafter sometimes referred to as nickel-based alloy powder) suitable for lamination forming, as well as a laminated article and a method for manufacturing the laminated article, for example, to a component or part used in an oxidation furnace used in semiconductor manufacturing or a calcination furnace for electronic components. Prior Technology

[0002] Generally, for components or parts placed in oxidation furnaces used in semiconductor manufacturing or calcination furnaces for electronic components, nickel-based alloys with excellent high-temperature oxidation resistance are used to prevent oxide scale generated from the components or parts from mixing into the finished product. For example, Patent Document 1 discloses a nickel-based alloy with excellent high-temperature oxidation resistance that contains, by mass percent (hereinafter, % is used to express mass percent), Al: 3.6% to 4.4%, and further contains, as needed, one or more of Si: 0.1% to 2.5%, Cr: 0.8% to 4.0%, and Mn: 0.1% to 1.5%, with the remainder containing Ni and unavoidable impurities. This alloy can be used as heat sinks or tubes for high-temperature heat exchangers.

[0003] In addition, Patent Document 2 proposes a nickel-based alloy with excellent hot forging properties and high-temperature oxidation resistance, which contains Al: 2.0%~5.0%, Si: 0.1%~2.5%, Cr: 0.8%~4.0%, Mn: 0.1%~1.5%, B: 0.001%~0.01%, Zr: 0.001%~0.1%, with the remainder being Ni and unavoidable impurities. [Existing Technical Documents] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2003-262491 [Patent Document 2] Japanese Patent Application Publication No. 2014-080675 Summary of the Invention

[0005] [The problem that the invention aims to solve] However, in recent years, applications in the manufacture of semiconductor products or electronic components, such as furnace components or parts, have demanded not only excellent resistance to high-temperature oxidation but also complex shapes such as gas flow paths within the components or parts. As a means of achieving such complex shapes, a known suitable method is the additive manufacturing method using alloy powders (hereinafter referred to as the lamination forming method in this invention). Here, while the nickel-based alloys described in Patent Document 1 or Patent Document 2 exhibit excellent resistance to high-temperature oxidation, their high Al content results in a high susceptibility to weld cracking (hereinafter sometimes referred to as crack sensitivity). The lamination forming method involves repeatedly melting and solidifying the powders, a process equivalent to microscopic welding. Therefore, it is readily apparent that even when using the nickel-based alloys described in Patent Document 1 or Patent Document 2, which have high weld crack sensitivity, in the lamination forming method, cracks will still occur. Furthermore, if the resistance to high-temperature oxidation is poor, defects caused by oxides become apparent. Based on the above, the purpose of this invention is to provide a nickel-based alloy powder that is free of cracks or defects and has excellent high-temperature oxidation resistance, suitable for manufacturing laminated articles, a laminated article using the nickel-based alloy powder, and a method for manufacturing the laminated article. [Methods for solving problems]

[0006] This invention relates to a nickel-based alloy powder for laminated molding, characterized in that it contains, by mass%, Al: 3.5%~5.5%, Cr: 0.8%~4.0%, C: 0.02%~0.06%, Si: 1.0%~1.8%, Mn: less than 1.5%, O: 0.001%~0.050%, with the remainder containing Ni and unavoidable impurities, wherein the Zr contained in the unavoidable impurities is limited to less than 0.01%.

[0007] In addition, the nickel-based alloy powder used for lamination forming preferably contains Al: 3.6%~5.0%, Cr: 1.5%~3.0%, C: 0.03%~0.05%, Si: 1.2%~1.5%, Mn: 0.2%~1.0%, and O: 0.008%~0.030%.

[0008] In addition, it is preferable that the Vickers hardness of the nickel-based alloy powder used for lamination forming is in the range of 160 HV to 220 HV.

[0009] Furthermore, the nickel-based alloy powder used for lamination forming is preferably such that, in the cumulative distribution curve obtained by laser diffraction, which represents the relationship between particle size and the cumulative volume from the smaller particle size side, the particle size d10 corresponding to the cumulative frequency 10 volume% of the powder is 10 μm or more and 25 μm or less, the particle size d50 corresponding to the cumulative frequency 50 volume% is 25 μm or more and 40 μm or less, and the particle size d90 corresponding to the cumulative frequency 90 volume% is 45 μm or more and 60 μm or less.

[0010] Furthermore, the uniformity represented by (d90-d10) / d50 is preferably in the range of 0.8 to 1.2.

[0011] In addition, the nickel-based alloy powder used for lamination shaping is preferably of an angle of repose of 40 degrees or less as measured according to Japanese Industrial Standards (JIS) R9301-2-2.

[0012] In addition, the present invention provides a method for manufacturing a laminated shaped article, characterized by a lamination forming step using nickel-based alloy powder to form the laminated shaped article. The nickel-based alloy powder contains, by mass%, Al: 3.5%~5.5%, Cr: 0.8%~4.0%, C: 0.02%~0.06%, Si: 1.0%~1.8%, Mn: less than 1.5%, O: 0.001%~0.050%, and the remainder contains Ni and unavoidable impurities, wherein Zr in the unavoidable impurities is limited to less than 0.01%.

[0013] Furthermore, the present invention is a laminated product characterized by containing, by mass%, Al: 3.5%~5.5%, Cr: 0.8%~4.0%, C: 0.02%~0.06%, Si: 1.0%~1.8%, Mn: less than 1.5%, O: 0.001%~0.050%, with the remainder containing Ni and unavoidable impurities. The Zr content in the unavoidable impurities is limited to less than 0.01%, the defect rate is less than 0.1%, and the oxidation amount per unit area, expressed as [mass reduction before and after oxidation test] / [surface area before oxidation test], obtained by an oxidation test conducted in an atmospheric furnace at 800°C for 950 hours, is less than 0.005 mg / mm².

[0014] The hardness of the laminated product is preferably in the range of 210 HV to 300 HV. [The effects of the invention]

[0015] The nickel-based alloy powder of the present invention is an alloy powder suitable for laminated forming, which not only has excellent resistance to high-temperature oxidation and low sensitivity to welding cracks, but is also suitable for defect suppression. When using the nickel-based alloy powder to manufacture components or parts for semiconductor or electronic parts manufacturing apparatus by laminated forming, laminated formed articles with few cracks or defects and excellent resistance to high-temperature oxidation, as well as components or parts containing the laminated formed articles, can be obtained. Simple Explanation of the Diagram

[0016] Figure 1 is a graph showing the oxidation test results of laminated articles based on embodiments and comparative examples of the present invention. Implementation

[0017] Nickel-based alloy powder In order to develop nickel-based alloy powders for lamination forming with excellent high-temperature oxidation resistance and lamination forming properties, the inventors have conducted intensive research on alloy composition and lamination forming methods. As a result, they discovered that the nickel-based alloy powders exhibit excellent properties in terms of high-temperature oxidation resistance and lamination forming properties with fewer cracks or defects. The nickel-based alloy powders contain, by mass%, Al: 3.5%~5.5%, Cr: 0.8%~4.0%, C: 0.02%~0.06%, Si: 1.0%~3.0%, Mn: less than 1.5%, O: 0.001%~0.050%, with the remainder containing Ni and unavoidable impurities, wherein the Zr content in the unavoidable impurities is limited to less than 0.01%.

[0018] The reasons for limiting the numerical values ​​of each component element in the nickel-based alloy powder of the present invention will be described in detail below. Next, the manufacturing method of the alloy powder and the laminated product will be described. Furthermore, in this specification, the numerical range indicated by "~" includes the values ​​before and after "~" as the lower and upper limits. Moreover, the upper and lower limits described in stages can be arbitrarily combined. Additionally, "%" in other words means "mass %".

[0019] (Al: 3.5%~5.5%) Al (Al) forms an alumina film on the surface of laminated products, thereby improving high-temperature oxidation resistance and reducing scale formation. Furthermore, even in nickel-based alloy powders, it forms a passivation film caused by oxides on the surface, preventing further oxidation of the nickel-based alloy powder; therefore, it is added. To ensure sufficient high-temperature oxidation resistance, the lower limit of Al content is 3.5%. On the other hand, if the Al content is too high, microcracks are easily generated during repeated local melting and solidification in laminated products; therefore, the upper limit of Al content is 5.5%. More preferably, the Al content is 3.6% to 5.0%, and even more preferably 3.7% to 4.1%.

[0020] (Cr: 0.8%~4.0%) Cr is an effective element used to improve the high-temperature oxidation resistance of alumina by stabilizing the alumina film. To ensure sufficient high-temperature oxidation resistance, the lower limit of Cr content is 0.8%. On the other hand, if the Cr content is too high, the formation of the alumina film will be hindered, so the upper limit of Cr content is 4.0%. In addition, the preferred Cr content is 1.5% to 3.0%, and more preferably 1.9% to 2.1%.

[0021] (C: 0.02%~0.06%) C is effective in reducing crack susceptibility, preventing shrinkage cavities during solidification, and improving tensile strength. To sufficiently reduce crack susceptibility, the lower limit for C content is 0.02%. On the other hand, if the C content is too high, Cr carbides will form, reducing corrosion resistance; therefore, the upper limit for C content is 0.06%. Furthermore, a preferred C content is 0.03% to 0.05%, and more preferably 0.035% to 0.04%.

[0022] (O: 0.001%~0.050%) O has the following effect: During the gas atomization step in nickel-based alloy powder manufacturing, it primarily combines instantaneously with Al to form an extremely thin and robust oxide film on the powder surface, thereby inhibiting further oxidation. To ensure sufficient resistance to high-temperature oxidation, the lower limit of the O content is 0.001%. On the other hand, if the O content is too high, the oxide film formed on the powder surface will become a defect during lamination forming; therefore, the upper limit of the O content is 0.050%. Furthermore, a more preferred O content is 0.008% to 0.030%, and even more preferably 0.010% to 0.015%.

[0023] Furthermore, the content of C and O can be controlled, for example, by dissolving them in a vacuum and using argon atomization to control the environment.

[0024] (Zr: below 0.01%) Zr is an unavoidable impurity introduced during the manufacture of nickel-based alloy powders. If the Zr content is high, oxides form, hindering the formation of the alumina film. Furthermore, due to grain boundary segregation, microcracks (crazing) easily form at the grain boundaries. From the viewpoint of avoiding these issues, Zr content is particularly limited. The target Zr content is 0%, with an upper limit set at 0.01%. Preferably, it is below 0.001%, and even more preferably below 0.0001%.

[0025] (Si: 1.0%~1.8%) Like Cr, Si enhances high-temperature oxidation resistance by stabilizing the alumina film formed in the laminated product. To ensure sufficient high-temperature oxidation resistance, the lower limit for Si content is 1.0%. On the other hand, if the Si content is too high, shrinkage cavities are easily formed during solidification of the nickel-based alloy powder during repeated melting and solidification processes; therefore, the upper limit for Si content is 1.8%. Furthermore, a preferred Si content is 1.2% to 1.6%, and more preferably 1.3% to 1.5%.

[0026] (Mn: below 1.5%) Mn has the effect of suppressing solidification cracking, which is increased due to the presence of Al. Furthermore, for example, when the lamination rate is increased, solidification cracking becomes more likely due to the increased heat input; therefore, it is preferable to adjust the amount added according to the lamination rate. This effect can be achieved by setting the Mn content to more than 0%. Furthermore, to effectively exert this effect, it is preferable to set the Mn content to 0.1% or more. On the other hand, if the Mn content exceeds 1.5%, the high-temperature oxidation resistance decreases. Therefore, the Mn content is specified to be 1.5% or less. Additionally, a preferred Mn content is 0.2% to 1.0%, and more preferably 0.4% to 0.6%.

[0027] (Remaining Ni and unavoidable impurities) Regarding unavoidable impurities, it is preferable if their total content is 1.0% or less. Each unavoidable impurity is preferably 0.5% or less, more preferably 0.1% or less. Furthermore, more specifically, for P, S, and N, it is preferably 0.01% or less, and for Fe, B, Ti, Cu, Nb, Mo, and Co, it is preferably 0.5% or less.

[0028] The composition of the nickel-based alloy powder in this embodiment can be determined by the following method. As described in the later examples, the graded lamination powder is dissolved in a suitable aqueous solution, and the content of the specified components is determined by high-frequency inductively coupled plasma (ICP) analysis of the aqueous solution. Furthermore, the contents of C, N, and O can be determined by gas analysis using a combustion method.

[0029] (Hardness of nickel-based alloy powder: 160 HV~220 HV) The hardness of the nickel-based alloy powder can be set to 160 HV or higher to prevent the particles from being crushed during powder laying. On the other hand, if the powder hardness is too high, the manufactured laminated products are prone to cracking, so the upper limit of the hardness can be set to 220 HV. In addition, 170 HV to 200 HV is preferred, and 180 HV to 190 HV is even more preferred.

[0030] (Particle size of nickel-based alloy powder: 1 μm~200 μm) Lamination shaping is a shaping method that uses repeated melting and solidification of powders to impart shape. Depending on the lamination shaping device, the particle size requirements of the alloy powder vary. Therefore, in order to be applicable to various shaping devices, the particle size range of nickel-based alloy powder can be set from 1 μm to 200 μm. For example, in the case of powder bed fusion (PBF), if the particle size of the nickel-based alloy powder is less than 1 μm, the flowability is reduced, making it difficult to obtain well-formed laminated products. On the other hand, if the particle size of the nickel-based alloy powder exceeds 80 μm, the lamination spacing needs to be set larger, resulting in reduced dimensional accuracy. Therefore, the particle size range of the nickel-based alloy powder used in powder bed fusion can be set to 1 μm to 80 μm. Preferably, it is 10 μm to 60 μm. Furthermore, in the case of Directed Energy Deposition (DED), if the particle size of the nickel-based alloy powder is less than 1 μm, the feed rate cannot be increased, resulting in a slower forming speed. On the other hand, if the particle size of the nickel-based alloy powder exceeds 200 μm, the volume required for a single melting and solidification step becomes too large, making it easier to generate molten residue. Therefore, the particle size range of the nickel-based alloy powder used in DED can be set to 20 μm to 200 μm. Preferably, it is 40 μm to 120 μm. Furthermore, it is preferable to obtain the powder by a gas atomization method that can produce a spherical shape. In addition, regarding the particle size of the powder, the particle size distribution can be determined using laser diffraction (laser diffraction particle size distribution measuring device).

[0031] (Particle size distribution of nickel-based alloy powder) In lamination forming, if the powder particle size is too small, the powder layer will wear or shift, thus reducing coatability. On the other hand, if the powder particle size is too large, the laser output will be insufficient, and there is a risk of molten residue, which tends to increase defects or reduce surface roughness during lamination. Therefore, in the cumulative distribution curve obtained by laser diffraction, which shows the relationship between particle size and the volume accumulation from the smaller particle size side, it is preferable that the particle size d10 corresponding to a cumulative frequency of 10% volume is set to a range of 10 μm or more and 25 μm or less, the particle size d50 corresponding to a cumulative frequency of 50% volume is set to a range of 25 μm or more and 40 μm or less, and the particle size d90 corresponding to a cumulative frequency of 90% volume is set to a range of 45 μm or more and 60 μm or less. Furthermore, it is preferable that d10 is 15 μm or more and 20 μm or less, d50 is 30 μm or more and 35 μm or less, and d90 is 50 μm or more and 55 μm or less; even more preferably, d10 is 18 μm or more and 20 μm or less, d50 is 32 μm or more and 34 μm or less, and d90 is 53 μm or more and 55 μm or less.

[0032] (Uniformity of nickel-based alloy powder: 0.8~1.2) Regarding the particle size of the nickel-based alloy powder of the present invention, the value expressed as (d90-d10) / d50 is defined as uniformity. There is a tendency that the greater the uniformity is than 1, the lower the layup quality; and the smaller the uniformity is than 1, the lower the yield and the lower the productivity. Therefore, the lower limit of uniformity is preferably set to the range of 0.8, and the upper limit is preferably set to the range of 1.2. Furthermore, 0.90 to 1.15 is preferred, and more preferably 0.95 to 1.10.

[0033] (Angle of repose of nickel-based alloy powder: below 40 degrees) In laminated molding, powders with good flowability exhibit better spreadability. The flowability of the nickel-based alloy powder of the present invention is evaluated according to the angle of repose in accordance with JIS R9301-2-2. If the angle of repose exceeds 40 degrees, the flowability is poor and the spreadability is reduced; therefore, the angle of repose is preferably 40 degrees or less. There is no particular limitation on the lower limit. Furthermore, a more preferred angle of repose is 35 degrees or less, and even more preferably 31 degrees or less. Furthermore, the flowability of the nickel-based alloy powder having the aforementioned angle of repose is preferably 15 sec / 50 g or more. More preferably, it is 18 sec / 50 g or more, and even more preferably, it is 19 sec / 50 g or more.

[0034] [Method for manufacturing alloy powder] One method for manufacturing nickel-based alloy powder (alloy powder) is gas atomization. Raw material powder of a specified composition is melted in a crucible, and the molten metal is then discharged from the bottom of the crucible while simultaneously spraying high-pressure gas onto the discharged molten metal. By using the kinetic energy of the high-pressure spray to atomize the molten metal into droplets, spherical nickel-based alloy powder can be produced. Furthermore, to prevent the introduction of Zr impurities, the crucible used in this process is preferably made of Al₂O₃.

[0035] [Manufacturing method for laminated shapes] The manufacturing method of the laminated shaped article of the present invention is as follows: a laminated shaped article manufacturing method comprising a laminated shaped article forming step using nickel-based alloy powder, wherein the nickel-based alloy powder contains, by mass %: Al: 3.5%~5.5%, Cr: 0.8%~4.0%, C: 0.02%~0.06%, Si: 1.0%~1.8%, Mn: less than 1.5%, O: 0.001%~0.050%, and the remainder contains Ni and unavoidable impurities, wherein the Zr in the unavoidable impurities is limited to less than 0.01%.

[0036] (Layered molding steps) The lamination method in the lamination forming step is not particularly limited. For example, the nickel-based alloy powder of the present invention is supplied to a powder bed fusion (PBF) lamination forming apparatus, and a high-energy laser beam, electron beam, or similar beam is irradiated onto the powder-coated area, causing the alloy powder to selectively fuse and bond, thereby lamination forming of a desired shape. As a lamination forming apparatus, it can be classified into powder bed fusion (PBF) and directed energy deposition (DED) methods, depending on the shape of the lamination formed product. The lamination formed product of this embodiment can be shaped in any way, and there are no particular limitations on the form of the lamination forming apparatus.

[0037] (Heat treatment of laminated shapes) In the method for manufacturing laminated articles of the present invention, solution heat treatment can also be performed on the articles produced by the laminated molding method for the purpose of removing residual stress and reducing microsegregation. Regarding the temperature during solution heat treatment, it is preferably set to 1000°C or higher to dissolve microsegregation; since it needs to be below the solidus temperature, it is preferably set to 1200°C or lower. More preferably, it is 1050°C or higher and 1180°C or lower, and even more preferably, it is 1100°C or higher and 1160°C or lower.

[0038] [Laminated shapes] The laminated product of the present invention is characterized by containing, by mass%, Al: 3.5%~5.5%, Cr: 0.8%~4.0%, C: 0.02%~0.06%, Si: 1.0%~1.8%, Mn: less than 1.5%, O: 0.001%~0.050%, with the remainder containing Ni and unavoidable impurities, wherein the Zr content in the unavoidable impurities is limited to less than 0.01%, the defect rate is less than 0.1%, and the oxidation amount per unit area, expressed as [mass reduction before and after oxidation test] / [surface area before oxidation test] obtained by an oxidation test conducted in an atmospheric furnace at 800°C for 950 hours, is less than 0.005 mg / mm², and is characterized by having excellent high-temperature oxidation resistance due to the alumina film formed on the surface layer. The application of the laminated product is not particularly limited; for example, it can be used to provide components for semiconductor manufacturing apparatuses comprising the laminated product. The laminated products exhibit exceptional resistance to high-temperature oxidation above 700°C, and even when used in high-temperature environments, the oxide film on the surface does not easily grow. Therefore, when these laminated products are applied to components or parts installed inside oxidation furnaces for semiconductor manufacturing or calcination furnaces for electronic component manufacturing, oxides are less likely to peel off from the surface of the components or parts, effectively preventing foreign matter from contaminating the semiconductor or electronic component products. Furthermore, these laminated products, with excellent high-temperature oxidation resistance and complex shapes, can be provided not only for components in semiconductor manufacturing equipment but also for parts in the aerospace, space, and automotive industries, chemical equipment, pharmaceutical manufacturing equipment, and energy fields such as oil and gas.

[0039] (Oxidation per unit area of ​​laminated products: less than 0.5 mg / cm²) The laminated articles of the present invention exhibit excellent resistance to high-temperature oxidation. Here, the resistance to high-temperature oxidation can be evaluated by the amount of oxidation per unit area as expressed in (Formula 1). If the amount of oxidation per unit area is less than 0.5 mg / cm² in a high-temperature oxidation test conducted in an atmospheric furnace at 800°C for 950 hours, the growth of the oxide film can be greatly suppressed. Furthermore, a more preferred amount of oxidation per unit area is less than 0.4 mg / cm², and a more preferred amount of oxidation per unit area is less than 0.3 mg / cm².

[0040] [Oxidation amount per unit area (mg / cm²)] = [Mass reduction before and after oxidation test (mg)] / [Surface area before oxidation test (cm²)] ···(Equation 1)

[0041] (Defect rate for laminated products: below 0.1%) Internal defects in laminated products become the starting point for cracking, so a low defect rate is ideal. The defect rate can be determined as the area ratio of defective areas such as voids or unmelted powder. Details of the measurement conditions will be described later. If the defect rate is 0.1% or less, there are very few internal defects that become the starting point for cracking, so the defect rate is set to 0.1% or less. Furthermore, a preferred defect rate is 0.05% or less, and an even more preferred defect rate is 0.025% or less.

[0042] (Hardness of laminated products: 210 HV~300 HV) In the laminated articles of the present invention, high tensile strength is desirable. Therefore, a hardness proportional to tensile strength is set to 210 HV or higher. On the other hand, from the viewpoint of maintaining machinability and preventing cracking, an upper limit for hardness is set to 300 HV. Furthermore, a preferred hardness range is 240 HV to 290 HV, and more preferably 260 HV to 280 HV. Details regarding the measurement conditions, etc., will be described later. [Example]

[0043] The embodiments of the present invention will be described below. First, as an example, alloy powder (hereinafter referred to as powder a) with the composition shown in Table 1 was prepared. Additionally, as a comparative example, alloy powders b to e with the compositions shown in Table 1 were prepared. Vacuum gas atomization was used in the method for manufacturing the alloy powders. For raw material powders prepared with the specified composition, alloy powders a, c, and e were melted in an Al₂O₃ crucible using a high-frequency vacuum melting furnace, while alloy powders b and d were melted in a ZrO₂ crucible. Then, argon gas was sprayed into the molten liquid flowing from the bottom of the crucible to refine the particles, which were then solidified in a cooling tower to obtain spherical powders. Subsequently, by classifying the obtained powders, alloy powders a to e with a particle size range of 10 μm to 60 μm were obtained.

[0044] [Table 1] alloy powder Composition (mass%) Ni Al Cr Si Mn Zr Fe C O N B P S a Bal. 3.99 2 1.33 0.44 <0.01 0.01 0.036 0.0116 0.0002 0.0027 0.001 0.0002 b Bal. 4.4 1.98 1.5 - 0.31 - 0.0055 0.0113 0.0002 - - - c Bal. 4.16 1.98 0.6 0.49 <0.01 0.01 0.0065 0.0074 0.0003 0.0003 0.001 0.0002 d Bal. 4.07 2.01 1.29 - 0.18 0.01 0.055 0.0049 0.0002 0.00092 0.001 0.0002 And Bal. 6.06 2 1.33 0.44 <0.01 0.01 0.034 0.0103 0.0002 0.0001 0.001 0.0003

[0045] The chemical composition of the alloy powders shown in Table 1 was analyzed, for example, using inductively coupled plasma (ICP) luminescence analysis. Comparing the composition of the example powders and comparative example powders shown in Table 1, it can be seen that, relative to powder a (as an example), powder b has a decreased C content and an increased Zr content; powder c has a decreased C and Si content; powder d has an increased Zr content; and powder e has an increased Al content.

[0046] [Property Evaluation of Nickel-Based Alloy Powder] For alloy powders a to e, the results obtained from the determination of flowability, angle of repose, and hardness are shown in Table 2. The determination apparatus or conditions are described below.

[0047] (Particle size and flowability evaluation) Particle size distribution was measured using a laser diffraction particle size distribution measuring device (Malvern Panalytical: Master Sizer 3000). Particle sizes d10, d50, and d90 were measured. The uniformity, represented by (d90-d10) / d50, was calculated using the measured d10, d50, and d90 values. In addition, as per JIS-Z2502, the flowability of the powder was measured using a flowability tester (manufactured by Tsutsui Rikikaku Co., Ltd.).

[0048] (Anchorage Evaluation) The angle of repose was measured using a multi-functional powder property analyzer (manufactured by Seishin: Multi Tester MT-02). The measurement was performed according to JIS R9301-2-2, specifically by feeding alloy powder into the tray inside the analyzer and measuring the angle of the resulting hill. A 355 μm sieve was used to supply the alloy powder.

[0049] (Hardness Evaluation) After filling 1 g of alloy powder into a 2 mm diameter hole, the alloy powder was embedded in resin using a cold resin embedding vacuum device (manufactured by Struers: CitoVac). The alloy powder embedded in the resin was then ground to #1500 with water-resistant diamond sandpaper, followed by mirror finishing with diamond paste in the order of 1 μm and 0.3 μm particle sizes, thereby obtaining test pieces for hardness evaluation. Regarding the mirror-finished surface, the Vickers hardness was determined using a micro Vickers hardness tester (manufactured by Future-tech: FM-110). Specifically, a diamond indenter with a square pyramidal shape was pressed into a total of 10 points relative to powder particles with a diameter of 30 μm to 40 μm, and held at a test load of 25 gf for 15 seconds. Afterwards, the length of the diagonal of the indentation remaining on the surface was measured, and the hardness was calculated. The average hardness and standard deviation of the hardness at the 10 points for each test piece were then determined.

[0050] [Table 2] alloy powder Particle size distribution Liquidity Uniformity Cape of Repose Hardness (average value) Standard deviation d10(μm) d50(μm) d90(μm) (sec / 50 g) Spend HV a 18.8 32.6 54.0 19.3 1.08 30.1 184.63 6.92 b 17.3 30.7 51.4 18.9 1.11 28.2 193.94 16.78 c 18.2 32.4 54.5 19.5 1.12 30.2 163.10 10.92 d 17.7 32.9 57.2 20.8 1.20 30.9 190.20 10.75 e 18.5 31.8 52.5 21.4 1.07 31.0 257.07 12.55

[0051] Table 2 shows the evaluation results of the flowability, angle of repose, and hardness of powders a to e. Comparing the measurement results of the examples and comparative examples, it can be seen that powder a satisfies the preferred range, and further satisfies an even better range, regarding flowability, particle size distribution, and uniformity, which are also related to spreadability.

[0052] On the other hand, comparing the hardness of the powders shown in Table 2, it can be seen that powder c has a lower hardness than powders a, b, and d, while powder e has a higher hardness. Regarding powder c, it is speculated that the decrease in Si content contributes to the decrease in powder hardness. Conversely, regarding powder e, it is speculated that the increase in Al content contributes to the increase in powder hardness. Furthermore, although no significant differences were found in the hardness of powders a, b, and d, the high standard deviation and large deviation of the measured values ​​for powders b and d suggest that powder a, as an example, achieved a more stable hardness.

[0053] [Characteristics Evaluation of Laminated Artworks] Using a lamination forming apparatus (manufactured by EOS Corporation: M290) that uses a laser as a heat source for laser melting (selective laser melting (SLM)), laminated shapes (hereinafter, also referred to as shapes) A ​​to E are made from alloy powders a to e respectively. Regarding the conditions for layer deposition, the parameters included in Equation 2 are set as follows to achieve an energy density of 20 J / mm³ to 200 J / mm³. In this embodiment, the laser power is set to 300 W, the scanning speed to 1000 mm / s, the scanning spacing to 0.1 mm, the layer thickness to 0.04 mm, and the energy density to 75 J / mm³.

[0054] [Energy density (J / mm³)] = [Laser power (W)] / ([Scanning speed (mm / s)] × [Scanning spacing (mm)] × [Slice thickness (mm)]) ···(Equation 2)

[0055] For laminated shapes A through E, sheet materials (25 mm × 25 mm × 5 mm) and blocks (10 mm × 10 mm × 10 mm) were prepared. The defect rate and hardness of laminated shapes A through E were evaluated, and the high-temperature oxidation resistance of laminated shapes A through C was further evaluated. The results are shown in Table 3 and Figure 1. The testing apparatus and conditions are described below.

[0056] (Defect Rate Evaluation) The cross-sections of laminated molded pieces A through E (10 mm × 10 mm × 10 mm) were cut off, and the pieces were embedded in resin using a thermoforming resin embedding vacuum apparatus (Struers: CitoPress-30). For the embedded laminated molded pieces, they were ground to #1500 with water-resistant diamond sandpaper, and then polished with diamond paste in the order of 1 μm and 0.3 μm grit to achieve a mirror finish, thereby obtaining test pieces for defect rate determination. Regarding the mirror-finished surface, crack formation and defect rate were confirmed and measured using a digital microscope (KEYENCE VHX-6000). If fine cracks were identifiable, defect rate evaluation was not performed. The defect rate was measured at one point in the center of the mirror-finished surface and four points approximately 1 mm away from the four corners. For each measurement area, 1.58 mm × 1.25 mm surface images were acquired. Blackened voids or unmelted powder, resulting from binarization of the acquired images, were defined as defects with an area of ​​0.18 μm² or more. The area ratio of the defective areas (defect rate) was then calculated, and the average and standard deviation of the defect rate at five points in each test piece were determined.

[0057] (Hardness Evaluation) Regarding the mirror-finished surface, the Vickers hardness was measured using a micro Vickers hardness tester (manufactured by Future-tech: FM-110). The test area was set at one point in the center of the mirror-finished surface and four points approximately 1 mm away from the four corners. Specifically, a diamond indenter with a square pyramidal shape was used to press in the surface, and a test load of 25 gf was applied for 15 seconds. Afterward, the length of the diagonal of the indentation remaining on the surface was measured, and the hardness was calculated. The average hardness and standard deviation of the five points in each test piece were then determined.

[0058] [Table 3] Laminated shapes hardness Defect rate average value Standard deviation average value Standard deviation HV area% A 267.13 10.49 0.016 0.005 B 204.66 17.69 cracks C 209.73 8.08 0.026 0.019 D 221.45 9.43 cracks E 314.41 6.73 cracks

[0059] Table 3 shows the hardness (HV) and defect rate (area %) of the laminated articles. According to the measurement results, articles A, D, and E have higher hardness than articles B and C. This is believed to be mainly because articles A, D, and E have a higher carbon content than articles B and C.

[0060] Furthermore, the test results show that molded products A and C also exhibit no fine cracks. Moreover, the defect rate of molded product A is 0.016%, and that of molded product C is 0.026%, both below 0.1%, which is excellent considering the high sensitivity of the composition system to weld cracks. It is believed that most defects in the original Zr-containing nickel-based corrosion-resistant alloy composition system are cracks. By limiting the content of alloy powder a, alloy powder c, and Zr to a low value below 0.01%, cracking can be prevented. On the other hand, molded products B, D, and E exhibited a large number of cracks. This is believed to be due to the high Zr content in molded products B and D, and the excessive Al content in molded product E. Additionally, it can be confirmed that molded products A and C are actually laminated molded products with high internal density and excellent laminated formability. However, the hardness of molded product C is lower, raising concerns about a potential decrease in tensile strength. Furthermore, regarding shapes B, D, and E, the defect rate cannot be calculated due to the large number of cracks produced.

[0061] (Evaluation of high-temperature oxidation resistance) To evaluate the high-temperature oxidation resistance of specimens A and C, which did not exhibit cracking in the aforementioned defect evaluation, a shaping material was prepared to maintain the shaped state of specimens A and C. Additionally, for comparison, a shaping material was also prepared for specimen B, which was an example of a sample exhibiting cracking. The surfaces of these specimens were ground to #400 using water-resistant diamond sandpaper, followed by electrolytic polishing. After electrolytic polishing, each specimen was degreased by ultrasonic vibration in acetone for 5 minutes, thereby obtaining high-temperature oxidation resistance test pieces. After measuring the mass of each test piece, an atmospheric miniature furnace was used to maintain the oxidation at 800°C for four stages: 250 hours, 500 hours, 750 hours, and 950 hours. After cooling to room temperature, the mass change of the test pieces was measured at each stage. For each test piece, the oxidation amount per unit area (mg / cm²) was calculated using the aforementioned formula (Equation 1). The measurement results are shown in Figure 1.

[0062] According to the high-temperature oxidation resistance test results shown in Figure 1, even after 950 hours, the oxidation amount per unit area of ​​specimen A remained at 0.23 mg / cm². On the other hand, specimen B showed 3.14 mg / cm², and specimen C showed 1.34 mg / cm², indicating significantly higher oxidation amounts. Specimen A demonstrated exceptionally excellent high-temperature oxidation resistance due to the sustained suppression of oxidation per unit area over a long period. This is believed to be because alloy powder a contains more Si than alloy powder c, thus stabilizing the alumina film formed on the surface of specimen A and inhibiting further oxidation. Conversely, specimen B, due to the higher Zr content in alloy powder b compared to alloy powder a or c, formed Zr oxide, hindering the formation of an alumina film on the surface and thus deteriorating its high-temperature oxidation resistance.

[0063] Based on the above test results, it can be confirmed that, compared with alloy powders b to e as comparative examples, alloy powder a, which is an example of nickel-based alloy powder for lamination forming of the present invention, has excellent high-temperature oxidation resistance and low crack sensitivity. In addition, it has flowability or hardness that is also suitable for defect suppression or layup forming. Furthermore, regarding the laminated molded articles made using alloy powder a, it can be confirmed that compared with the molded articles B to E of the comparative examples, molded article A of the example is also superior in terms of hardness, defect rate, and high-temperature oxidation resistance.

[0064] none

Claims

1. A nickel-based alloy powder for lamination molding, characterized in that it contains, by mass%, Al: 3.5%–5.5%, Cr: 0.8%–4.0%, C: 0.02%–0.06%, Si: 1.0%–1.8%, Mn: less than 1.5%, O: 0.001%–0.050%, with the remainder comprising Ni and unavoidable impurities, wherein Zr in the unavoidable impurities is limited to less than 0.01%.

2. The nickel-based alloy powder for lamination forming as described in claim 1, wherein, The composition by mass% is as follows: Al: 3.6%–5.0%, Cr: 1.5%–3.0%, C: 0.03%–0.05%, Si: 1.2%–1.5%, Mn: 0.2%–1.0%, O: 0.008%–0.030%.

3. The nickel-based alloy powder for lamination forming as described in claim 1 or 2, wherein, The Vickers hardness ranges from 160 HV to 220 HV.

4. The nickel-based alloy powder for lamination forming as described in claim 1 or 2, wherein, In the cumulative distribution curve obtained by laser diffraction, which represents the relationship between particle size and the cumulative volume from the smaller particle size side, the particle size d10 corresponding to a cumulative frequency of 10 volume% is 10 μm or more and 25 μm or less, the particle size d50 corresponding to a cumulative frequency of 50 volume% is 25 μm or more and 40 μm or less, and the particle size d90 corresponding to a cumulative frequency of 90 volume% is 45 μm or more and 60 μm or less.

5. The nickel-based alloy powder for lamination forming as described in claim 4, wherein, The uniformity represented by (d90-d10) / d50 is in the range of 0.8 to 1.

2.

6. The nickel-based alloy powder for lamination forming as described in claim 1 or 2, wherein, The angle of repose, as measured according to Japanese Industrial Standard R9301-2-2, is 40 degrees or less.

7. A method for manufacturing a laminated shaped article, characterized by comprising a lamination step of forming the laminated shaped article using nickel-based alloy powder, wherein the nickel-based alloy powder contains, by mass%, Al: 3.5%–5.5%, Cr: 0.8%–4.0%, C: 0.02%–0.06%, Si: 1.0%–1.8%, Mn: less than 1.5%, O: 0.001%–0.050%, and the remainder contains Ni and unavoidable impurities, wherein the unavoidable impurities, in which Zr is limited to less than 0.01%.

8. A laminated product, characterized in that it contains, by mass%, Al: 3.5%–5.5%, Cr: 0.8%–4.0%, C: 0.02%–0.06%, Si: 1.0%–1.8%, Mn: less than 1.5%, O: 0.001%–0.050%, with the remainder comprising Ni and unavoidable impurities, wherein the Zr contained in the unavoidable impurities is limited to less than 0.01%, the defect rate is less than 0.1%, and the amount of oxidation per unit area, expressed as [mass reduction before and after oxidation test] / [surface area before oxidation test], obtained by an oxidation test conducted in an atmospheric furnace at 800°C for 950 hours, is less than 0.005 mg / mm².

9. The laminated article as described in claim 8, wherein, The Vickers hardness is in the range of 210 HV to 300 HV.

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