JP7678686B2 - Shaped body made of Cu-based alloy - Google Patents

Description

The present invention relates to a shaped body made of a Cu-based alloy. In particular, the present invention relates to a shaped body made of a Cu-based alloy produced by an additive manufacturing method using a Cu-based alloy powder.

3D printers are beginning to be used to create metal objects. These 3D printers create objects using additive manufacturing, and typical methods of metal additive manufacturing include the powder bed method (powder bed fusion method) and the metal deposition method (directed energy deposition method). In the powder bed method, the irradiated areas of the spread powder are melted and solidified by irradiation with a laser beam or electron beam. This melting and solidification bonds the powder particles together. Irradiation is selectively applied to parts of the metal powder, and the unirradiated areas do not melt, and a bond layer is formed only in the irradiated areas.

New metal powder is then laid on top of the bonded layer, and the metal powder is irradiated with a laser beam or electron beam. The metal particles melt and solidify as a result of the irradiation, forming a new bonded layer. The new bonded layer also bonds with the existing bonded layer.

By repeatedly melting and solidifying the material by irradiation with a laser beam or the like, the aggregate of bonding layers gradually grows. This growth results in a three-dimensional object. By using this type of additive manufacturing method, objects with complex shapes can be easily obtained.

The powder bed additive manufacturing method uses a mixture of "iron-based powder" and "one or more types of powder selected from the group consisting of nickel, nickel-based alloys, copper, copper-based alloys, and graphite" as the metal powder for metal laser sintering, and the steps of forming a powder layer by spreading the metal powder, forming a sintered layer by irradiating the powder layer with a beam, and forming a removal step by cutting the surface of the sintered body are repeated to form the sintered layer, thereby producing a three-dimensional shaped body (see Patent Document 1).

In conventional additive manufacturing methods using metal powders, maraging steel, stainless steel, Ti (titanium), etc. are used. In recent years, there has been a demand for Cu (copper), Al (aluminum), etc. as materials for additive manufacturing. In particular, Cu and Cu-based alloys are suitable for applications where high electrical conductivity is required in the resulting molded body.

In additive manufacturing, a fiber laser or YAG laser in the near-infrared wavelength range (near 1000 nm wavelength) is usually used to rapidly melt the metal material, and then rapidly cool it to solidify it. However, Cu and Cu-based alloys have high thermal conductivity and large energy diffusion. For example, when irradiated with a YAG laser with a wavelength of 1064 nm, the laser light absorption rate of pure Cu is low at about 10%. Due to this low laser light absorption rate, there is a problem that it is difficult to melt Cu and Cu-based alloys by laser irradiation, or even if it can be melted, the energy efficiency is extremely low.

Furthermore, pure Cu has a high laser reflectance compared to Fe-based alloys, Ni-based alloys, Co-based alloys, etc. When pure Cu powder is used in a process involving rapid melting, rapid cooling, and solidification, such as additive manufacturing, a lot of heat is released into the atmosphere due to the high laser reflectance. Therefore, the powder is not given enough heat to melt. The lack of heat leads to poor bonding between the particles. Due to the lack of heat, unmelted particles remain inside the molded body obtained from this powder. As a result, the relative density of this molded body is low.

It is true that if a laser with a high energy density is irradiated onto pure Cu powder, the remaining unmelted particles are suppressed. However, irradiating a laser with a high energy density leads to bumping of the molten metal. This bumping is one of the causes of voids inside the molded object. The relative density of a molded object with voids will be low, so it is not enough to just irradiate it with a laser with a high energy density.

Patent Document 2 proposes a technology for improving the absorption rate of the shaping light beam by irradiating metal powder with an assist light beam having a different wavelength from the shaping light beam and forming an oxide film on the surface of the metal powder (see Patent Document 2).

In addition, as a raw material for additive manufacturing, a copper powder body made of copper or a copper alloy and a copper powder having an oxide film formed on the surface of the copper powder body by heat treatment in the presence of oxygen have been proposed (see Patent Document 3).

JP 2008-81840 A JP 2017-141505 A JP 2019-123920 A

The powders for additive manufacturing disclosed in Patent Documents 2 and 3 have an oxide film formed on the surface, and therefore their production requires a specific oxidation treatment, which makes their production time-consuming.
In addition, in a Cu-based alloy, if an additive element is dissolved in the copper matrix, it impedes thermal conduction, so by subjecting the molded body to an aging heat treatment after additive manufacturing, the additive element is expelled from the copper matrix as a precipitate, and the thermal conductivity of copper can be restored. However, if the precipitate that is expelled (the additive element alone, or an intermetallic compound of copper and the additive element) is too large, it will block the path of thermal conduction.
Therefore, the object of the present invention is to obtain a shaped body made of a Cu-based alloy having a high relative density, high thermal conductivity, and a precipitate size of 20 μm or less, which is produced by an additive manufacturing method using a Cu-based alloy powder that is obtained without the need for any special oxidation treatment and that has a high laser light absorption rate and can produce high-density shaped bodies.

After extensive research, the inventors discovered that in a Cu-based alloy containing Cr (chromium) and a specific element with a lower standard energy of oxide formation than Cr, laser irradiation during additive manufacturing promotes oxide formation and significantly improves laser light absorption. Using this Cu-based alloy powder, they were able to obtain a shaped body made of a Cu-based alloy with high relative density and excellent thermal conductivity.

First, the Cu-based alloy powder used for the shaped body according to the present invention is a Cu-based alloy containing "Cr" and "one or more elements selected from the group consisting of Nd, Gd, Dy, and Y."
The total content of Nd (neodymium), Gd (gadolinium), Dy (dysprosium) and Y (yttrium) in this Cu-based alloy is, in mass%, 0.10% to 5.00%.
Therefore, the first means for solving the problems of the present invention is a shaped body made of a Cu-based alloy having a precipitate size of 20 μm or less, using a Cu-based alloy powder containing, in mass%, 0.10 to 1.00% Cr, and 0.10 to 5.00% in total of one or more of Nd, Gd, Dy, and Y, with the remainder being Cu and unavoidable impurities.

The second means is a shaped body made of a Cu-based alloy having a precipitate size of 20 μm or less, which is produced by additive manufacturing using the Cu-based alloy powder described in the first means, in which the Si, P, and S in the unavoidable impurities are Si: 0.20% or less, P: 0.100% or less, and S: 0.100% or less.
In other words, the Cu-based alloy powder described in the second means is the Cu-based alloy powder described in the first means, and is characterized in that, among the unavoidable impurities of the Cu-based alloy powder, the Si content is 0.20% or less, the P content is 0.10% or less, and the S content is 0.10% or less. Therefore, the second means of the present invention is a shaped body made of a Cu-based alloy having a precipitate size of 20 μm or less, which is produced by additive manufacturing using the Cu-based alloy powder.

The Si in the Cu-based alloy powder of the present invention is not intentionally added, but is an unavoidable impurity. Therefore, the Si content in the Cu-based alloy powder of the present invention may be 0%, with the upper limit being 0.20%. In addition, since P and S in the Cu-based alloy powder are also unavoidable impurities, they may both be 0%, with the upper limits for P and S each being 0.10%.

Preferably, the Cu-based alloy powder has a ratio of average particle diameter D ₅₀ (μm) to tap density TD (Mg/m ³ ), D ₅₀ /TD, of 0.2×10 ^-5 ·m ⁴ /Mg or more and 20×10 ^-5 ·m ⁴ /Mg or less.

Therefore, the third means is a shaped body made of a Cu-based alloy having a precipitate size of ₂₀ μm or ^less , which is produced by additive manufacturing using the Cu ^- based alloy powder described in the first or second means, and in which the ratio of average particle diameter D ₅₀ (μm) to tap density TD (Mg/m ³ ), D 50 /TD, is 0.2 x 10 -5 to 20 x 10 -5 ·m ⁴ /Mg and the sphericity is 0.80 to 0.95.

In addition, the oxygen (O) content in the Cu-based alloy powder is preferably 0.1% (1000 ppm) or less.

In addition, the sphericity of the Cu-based alloy powder is preferably 0.80 to 0.95 or less.

Preferably, the Cu-based alloy powder has a laser light absorption rate of 30% or more at a wavelength of 1064 nm.

The Cu-based alloy powder according to the present invention has a high laser light absorption rate, so by applying this Cu-based powder to additive manufacturing, a high-density molded body can be obtained. This is because there is no need to excessively increase the energy density during irradiation, and molded objects can be obtained while avoiding bumping and the like. Furthermore, by making the precipitate size in the molded object 20 μm or less, the heat conduction path is less likely to be blocked by the precipitates even after aging treatment, so a molded object with excellent thermal conductivity can be obtained.

Prior to describing the embodiments of the present invention, the reasons for specifying the component composition of the Cu-based alloy powder used for additive manufacturing of the shaped body of the present invention will be described.
In this specification, unless otherwise specified, the "average particle size" refers to the particle size _D50 (median size) at the point where the cumulative volume is 50% in a volume-based cumulative curve obtained by a laser diffraction scattering method. The range "X to Y" means "X or more and Y or less." In addition, % in the composition of the Cu-based alloy powder means mass %, and ppm means mass ppm.

The Cu-based alloy powder (hereinafter sometimes referred to as "alloy powder") used in the additive manufacturing of the shaped body of the present invention is an aggregate of many particles. The material of each particle is a Cu-based alloy.

[Cu-based alloy]
The Cu-based alloy powder used in the additive manufacturing of a shaped body of the present invention contains Cr and one or more elements selected from the group consisting of Nd, Gd, Dy, and Y, with the balance being Cu and unavoidable impurities. The total content of Nd, Gd, Dy, and Y in this Cu-based alloy is 0.10 to 5.00%.
When the Cu-based alloy contains Si, P, and S as unavoidable impurities, the contents are preferably Si: 0.20% or less, P: 0.10% or less, and S: 0.10% or less.

This Cu-based alloy powder can achieve high laser light absorption without requiring a special oxidation treatment to form an oxide film. Therefore, the powder particles made of this Cu-based alloy can be rapidly melted even by laser irradiation with a low energy density. Therefore, this Cu-based alloy powder can obtain a high-density shaped body by the additive manufacturing method without causing bumping of the molten metal. Furthermore, this Cu-based alloy powder can also have the effect of suppressing oxidation due to changes over time during storage. Therefore, by using this Cu-based alloy powder as a material for the additive manufacturing method, a shaped body having desired characteristics can be stably manufactured at a high density.
The reasons for defining each component of the Cu-based alloy powder are as follows.

[Cr:0.10-1.00%]
In a Cu-based alloy containing Cr, Cr dissolves in Cu to form a solid solution. In this solid solution, the laser reflectance is suppressed. When a particle made of a Cu-based alloy containing Cr is irradiated with a laser, the heat is efficiently absorbed and an oxide containing Cr is generated. Therefore, the Cr content in this Cu-based alloy is set to 0.10 to 1.00%. From the viewpoint of facilitating the formation of an oxide layer, the preferred Cr content is 0.15% or more. From the viewpoint of not impeding the electrical conductivity of the resulting shaped body, the preferred Cr content is 0.50% or less.

[0.10 to 5.00% in total of one or more of Nd, Gd, Dy and Y]
The standard energy of formation of oxides of Nd, Gd, Dy and Y is lower than that of Cr. In the particles made of a Cu-based alloy containing Cr and one or more selected from the group consisting of Nd, Gd, Dy and Y, the generation of oxides is promoted by laser irradiation, and an oxide layer coating is quickly formed on the surface without the need for a special separate processing step. At that time, the oxide layers of Nd, Gd, Dy and Y contribute to further improvement of the laser light absorption rate in combination with the Cr oxide. Nd, Gd, Dy and Y also contribute to improvement of the adhesion and stability of the formed oxide layer. Therefore, the total content of Nd, Gd, Dy and Y in this Cu-based alloy is 0.10 to 5.00%. From the viewpoint of the formation and adhesion of the oxide layer, the preferred total content is 0.15% or more. From the viewpoint of handling and safety during production, the preferred total content is 3.0% or less.

[Si (silicon), P (phosphorus) and S (sulfur)]
In the Cu-based alloy powder used in the present invention, Si, P, and S are all unavoidable impurities. The content of each of these impurities is preferably within the following ranges. Note that none of Si, P, or S may be contained at all in the Cu-based alloy powder.
Si: 0 to 0.20% or less P: 0 to 0.100% or less S: 0 to 0.100% or less

Si is an inevitable impurity. Si dissolves in Cu and inhibits electrical and thermal conduction of Cu-based alloys. Therefore, the content of Si as an inevitable impurity is preferably 0.20% or less, more preferably 0.10% or less, and even more preferably 0.05% or less. Furthermore, the content of Si may be 0.

P is an inevitable impurity. P dissolves in Cu and inhibits the electrical and thermal conduction of Cu-based alloys. Therefore, the content of P as an inevitable impurity is preferably 0.100% or less, more preferably 0.010% or less, and even more preferably 0.005% or less. Furthermore, the content of P may be 0.

S is an inevitable impurity. S dissolves in Cu and inhibits electrical and thermal conduction of Cu-based alloys. Therefore, the content of S as an inevitable impurity is preferably 0.100% or less, more preferably 0.010% or less by mass, and particularly preferably 0.005% or less. Furthermore, the content of S may be 0.

[O (oxygen)]
The Cu-based alloy powder may contain O as an inevitable impurity. O may generate oxides of the above-mentioned elements during the production and storage of the alloy powder. In particular, the oxides generated during storage may change the laser absorption rate, thereby reducing the manufacturing stability during additive manufacturing. Therefore, the oxygen content in the Cu-based alloy powder is preferably 1000 ppm or less, more preferably 500 ppm or less. The lower the oxygen content, the more preferable it is, and the lower limit is not particularly limited.

[D ₅₀ /TD: ^{0.2×10 -5} ~20×10 ^-5・m ⁴ /Mg]
In this Cu-based alloy powder, the ratio "D ₅₀ /TD" of its average particle diameter D ₅₀ (μm) to its tap density TD (Mg/m ³ ) is preferably 0.2×10 ^-5 to 20×10 ^-5 ·m ⁴ /Mg.
^An alloy powder having a ratio " _D50 /TD" of 0.2 x ^10-5m4 /Mg or more has excellent fluidity. More preferably, the ratio " _D50 /TD" is 0.5 x ^10-5m4 / ^Mg or more, and even more preferably, the ratio is 5.0 x ^10-5m4 / ^Mg or more.
If the ratio " _D50 /TD" exceeds ^20x10-5 · ^m4 /Mg, the shaped body tends to have a low relative density. Therefore, in order to obtain a shaped body with a high relative density, it is preferable that the ratio " _D50 /TD" is ^20x10-5 · ^m4 /Mg or less. More preferably, the ratio _D50 /TD is ^18x10-5 · ^m4 /Mg or less. Even more preferably, it is ^15x10-5 · ^m4 /Mg or less.

[Average particle size _D50 of Cu-based alloy powder]
As long as the above-mentioned ratio _D50 /TD satisfies the predetermined value, the numerical range of the average particle diameter _D50 of the alloy powder itself is not particularly limited, but from the viewpoint of flowability, the average particle diameter _D50 of the alloy powder is preferably 15 μm or more, more preferably 20 μm or more, and even more preferably 25 μm or more.
On the other hand, from the viewpoint of increasing the density of the shaped body, the average particle size D ₅₀ of the alloy powder is preferably 50 μm or less, more preferably 40 μm or less, and particularly preferably 30 μm or less.

In measuring the average particle diameter _D50 , a cumulative curve is obtained with the total volume of the alloy powder taken as 100%. The particle diameter (median diameter) at the point on this curve where the cumulative volume is 50% is the average particle diameter _D50 . The average particle diameter _D50 can be measured by a laser diffraction scattering method. An example of a device suitable for this measurement is the Microtrac MT3000 laser diffraction/scattering particle size distribution measuring device manufactured by Nikkiso Co., Ltd. In this device, the alloy powder is poured into the cell of the device together with pure water, and the particle diameter is detected based on the light scattering information of the particles.

[Tap density TD of Cu-based alloy powder]
As long as the above-mentioned ratio _D50 /TD satisfies a predetermined value, the tap density TD of the alloy powder itself is not particularly limited. However, from the viewpoint of ease of manufacturing a shaped body, the tap density TD of the alloy powder is preferably 0.10 Mg/m3 or ^more and 0.40 Mg/m3 or ^less , and particularly preferably 0.15 Mg/m3 or ^more and 0.35 Mg/ ^m3 or less.

The tap density TD is measured in accordance with the standard of "JIS Z2512". In the measurement, about 50 g of alloy powder is filled into a cylinder having a volume of 100 cm3, and the tap density is measured. The measurement conditions are as follows:
Drop height: 10mm
Number of taps: 200

[Sphericity of Cu-based alloy powder: 0.80 to 0.95]
The sphericity of this Cu-based alloy powder is preferably 0.80 or more and 0.95 or less. An alloy powder having a sphericity of 0.80 or more has excellent flowability. From this viewpoint, the sphericity is more preferably 0.83 or more, and particularly preferably 0.85 or more. In an alloy powder having a sphericity of 0.95 or less, reflection of a laser can be suppressed. From this viewpoint, the sphericity is more preferably 0.93 or less, and particularly preferably 0.90 or less.

In measuring sphericity, a test piece is prepared in which Cu-based alloy powder is embedded in resin. The test piece is mirror-polished, and the polished surface is observed under an optical microscope. The magnification of the microscope is 100x. Image analysis is performed on 20 randomly selected alloy particles, and the sphericity of the alloy particles is measured. The sphericity of an alloy particle is the ratio of the length in the direction perpendicular to the longest line segment that can be drawn within the outline of the alloy particle to the length of the longest line segment. The average of the 20 measured values is the sphericity of the alloy powder.

[Laser light absorptivity of Cu-based alloy powder]
As described above, the Cu-based alloy powder according to the present invention has a high laser light absorption rate. In a laser-type metal additive manufacturing machine, a YAG laser with a wavelength of 1064 nm or a fiber laser with a wavelength of about 1000 to 1100 nm is widely used. From the viewpoint of obtaining a shaped body by additive manufacturing, it is preferable that the Cu-based alloy powder has a high laser light absorption rate. Therefore, the Cu-based alloy powder preferably has a laser light absorption rate of 30% or more at a wavelength of 1064 nm. More preferably, the laser light absorption rate of 50% or more at a wavelength of 1064 nm is described below in the examples.

[Precipitate size: 20 μm or less]
As a characteristic of a shaped body made of a Cu-based alloy produced by additive manufacturing using a Cu-based alloy powder, the size of precipitates in the Cu-based alloy is set to 20 μm or less.
In a Cu-based alloy, when an additive element is dissolved in a copper matrix, the additive element impedes thermal conduction. When a Cu-based alloy is manufactured by additive manufacturing using a Cu-based alloy powder, the additive element is discharged as a precipitate from the copper matrix by subjecting the manufactured body to an aging heat treatment, thereby recovering the thermal conductivity of the copper.
However, if the discharged precipitates (the added element alone or the intermetallic compound of copper and the added element) are too large, they will block the thermal conduction path, so the size of the precipitates in the Cu-based alloy in the shaped body made of the Cu-based alloy is set to 20 μm or less.

[Method of producing Cu-based alloy powder]
The method for producing the Cu-based alloy powder is not particularly limited, and examples thereof include water atomization, gas atomization, disk atomization, and centrifugal atomization. Preferred production methods are gas atomization and disk atomization. The Cu-based alloy powder may be subjected to mechanical milling or the like. Examples of milling methods include ball milling, bead milling, planetary ball milling, attritor method, and vibration ball milling.

[molding]
The Cu-based alloy powder according to the present invention can be used to obtain shaped bodies of various shapes by an additive manufacturing method.
A 3D printer can be used for the additive manufacturing method. In this additive manufacturing method, for example, in the powder bed method, a laser beam or an electron beam is irradiated onto a Cu-based alloy powder that has been spread out. The alloy particles in the irradiated area are rapidly heated and melted by the irradiation. The alloy particles then rapidly solidify. This melting and solidification bonds the alloy particles in the irradiated area. The irradiation is selectively performed on a part of the alloy powder. The parts of the alloy powder that are not irradiated do not melt. A bonding layer made of a Cu-based alloy is formed only in the irradiated area.

Cu-based alloy powder is further spread on top of the bonding layer. This alloy powder is irradiated with a laser beam or electron beam. The irradiation causes the Cu-based alloy particles to melt rapidly. The alloy particles then rapidly solidify. This melting and solidification bonds the Cu-based alloy particles in the Cu-based alloy powder together, forming a new Cu-based alloy bonding layer. The new bonding layer also bonds with the existing bonding layer.

By repeating the bonding by irradiation, an aggregate of bonding layers made of Cu-based alloy gradually grows. This growth results in a shaped body made of Cu-based alloy with a three-dimensional shape. In other words, by using an additive manufacturing method in which the irradiation position is set in advance and additive manufacturing is repeated, it is possible to easily obtain a shaped body with a complex shape.

[Modeling conditions]
The shaping conditions are appropriately selected depending on the physical properties of the Cu-based alloy powder, the composition of the Cu-based alloy, etc., but the preferred energy density E.D. is 100 to 350 J/ ^mm3 . When the energy density E.D. is 100 J/ ^mm3 or more, sufficient heat is applied to the alloy powder, so that the remaining unmelted alloy powder inside the shaped body is suppressed. In addition, since it is desirable for the relative density of this shaped body to be large, the energy density E.D. is more preferably 120 J/mm3 or ^more . Even more preferably, the energy density E.D. is 140 J/ ^mm3 or more.
On the other hand, if the energy density E.D. exceeds 350 J/mm ³ , excessive heat is applied to the Cu-based alloy powder. Therefore, it is preferable that the energy density E.D. is 350 J/mm ³ or less. By suppressing bumping of the molten metal, voids inside the shaped body are suppressed. Therefore, it is more preferable that the energy density E.D. is 300 J/mm ³ or less. Even more preferable that the energy density E.D. is 250 J/mm ³ or less.

[Relative density]
The relative density of the Cu-based alloy shaped body obtained by the additive manufacturing method (i.e., the shaped body before the heat treatment described below) is preferably 90% or more. If the relative density of this unheat-treated shaped body is high, it will have excellent dimensional accuracy and electrical conductivity. Therefore, the relative density is more preferably 93% or more, and particularly preferably 95% or more.

The relative density of the molded body is calculated based on the ratio of the density of a 10 mm square test piece produced by the additive manufacturing method to the theoretical density of the alloy powder, which is the raw material. The density of the 10 mm square test piece is measured by the Archimedes method. The theoretical density of the alloy powder is calculated from the theoretical density of each element constituting the alloy. For example, in the case of a Cu-based alloy consisting of 99% by mass of Cu and 1% by mass of Cr, the theoretical density of the alloy powder is calculated based on the following formula.
Theoretical density of alloy powder (g/cm ³ )=Theoretical density of Cu (g/cm ³ )×0.99+Theoretical density of Cr (g/cm ³ )×0.01

[Electrical conductivity of the molded object]
The electrical conductivity of the shaped body (i.e., the shaped body before being subjected to the heat treatment described below) is preferably 50 IACS% or more, and more preferably 80 IACS% or more. The method and conditions for measuring the electrical conductivity will be described later in the Examples.

[Heat treatment]
The molded body obtained by the additive manufacturing method is subjected to a heat treatment as necessary. A preferred heat treatment is an aging treatment. The aging treatment improves the electrical conductivity of the molded body.

[Heat treatment conditions]
In the aging treatment, the untreated shaped body is held at a predetermined temperature for a predetermined time. From the viewpoint of improving electrical conductivity, the aging temperature is preferably 350° C. or higher, more preferably 400° C. or higher, and particularly preferably 450° C. or higher. Similarly, from the viewpoint of electrical conductivity, the aging temperature is preferably 1000° C. or lower, more preferably 950° C. or lower, and particularly preferably 900° C. or lower.

From the viewpoint of improving electrical conductivity, the aging treatment time is preferably 1 hour or more, more preferably 1.3 hours or more, and particularly preferably 1.5 hours or more. On the other hand, from the viewpoint of energy costs, the aging time is preferably 10 hours or less, more preferably 9.7 hours or less, and particularly preferably 9.5 hours or less.

Below, an embodiment of a shaped body made of a Cu-based alloy formed by additive manufacturing using Cu-based alloy powder is explained using examples, and the effects of the present invention are demonstrated. However, it should be noted that the present invention should not be interpreted in a limited manner based on the description of the examples.

[Production of Cu-based alloy powder]
In a vacuum, raw materials of each composition of Examples No. 1 to 22 and Comparative Examples No. 1 to 10 shown in Tables 1 and 2 were heated by high-frequency induction heating in an alumina crucible and melted. The molten metal was taken out from a nozzle with a diameter of 5 mm provided at the bottom of the crucible. Argon gas was sprayed into the molten metal, and a large number of particles were obtained by a gas atomization method. These particles were classified to remove particles with a diameter of more than 63 μm, thereby obtaining the Cu-based alloy powders of Examples No. 1 to 22 and Comparative Examples No. 1 to 10.
Tables 1 and 2 show the ratio "D ₅₀ /TD" and sphericity of each alloy powder, determined by the above-mentioned method.

[Oxygen content]
In accordance with the provisions of JIS Z2613 "General Rules for the Quantitative Method of Oxygen in Metallic Materials", the oxygen content (ppm by mass) of the Cu-based alloy powders of the Examples and Comparative Examples was quantified by a combustion method. The combustion method is a method in which a sample is heated in a graphite crucible, the amount of CO gas generated is measured by a non-dispersive infrared absorption method, and the amount of oxygen contained in the sample is measured. The oxygen content (ppm by mass) of the Cu-based alloy powders of the Examples and Comparative Examples was measured. For the measurement, an oxygen/nitrogen analyzer (trade name "EMGA-620W" by Horiba, Ltd.) was used. The measurement results are shown in Tables 1 and 2.

[Measurement of laser light absorptance]
For the Cu-based alloy powders of the examples and comparative examples, the total reflectance (%) at a wavelength of 1064 nm was measured using an ultraviolet-visible-near infrared spectrophotometer (manufactured by JASCO Corporation under the trade name "V-770DS"), and the laser light absorptance (%) was calculated using the following formula.
Laser light absorptance (%) = 100 - total reflectance (%)
The results obtained are shown in Tables 1 and 2.

[molding]
The Cu-based alloy powders of the examples and comparative examples were used as raw materials, and an additive manufacturing method was carried out using a three-dimensional additive manufacturing device (EOS Corporation's product name "EOS-M280") to obtain shaped bodies (unheat-treated shaped bodies). The energy density E.D. (J/mm3) in the additive manufacturing method is shown in Tables 1 and 2. The shapes of the shaped bodies were all cubes with sides of 10 mm. The relative densities (%) of the obtained shaped bodies measured by the above-mentioned method are shown in Tables 1 and 2.

[Measurement of Electrical Conductivity]
The Cu-based alloy powders of the examples and comparative examples were each arc-melted to obtain an ingot. The obtained ingot was cut to prepare a plate-shaped test piece (3×2×60 mm), and the electrical resistance value (Ω) was measured by a four-terminal method in accordance with "JIS C 2525." For the measurement, an apparatus "TER-2000RH type" manufactured by ULVAC-RIKO was used. The measurement conditions were as follows.
Temperature: 25℃
Current: 4A
Voltage drop distance: 40 mm
The electrical resistivity ρ (Ωm) was calculated based on the following formula.
ρ = R/I × S
In this formula, R is the electrical resistance value (Ω) of the test piece, I is the current (A), and S is the cross-sectional area (m2) of the test piece. The electrical conductivity (S/m) was calculated from the reciprocal of the electrical resistivity ρ. In addition, the electrical conductivity (%IACS) of each test piece was calculated by taking 5.9×107 (S/m) as 100% IACS. The results are shown in Tables 1 and 2.

[Evaluation 1]
Based on the laser light absorptance obtained by measuring each alloy powder, the alloy powders were ranked according to the following criteria.
Evaluation value 1: Laser light absorptance is 50% or more.
Evaluation value 2: Laser light absorptance is 30% or more and less than 50%.
Evaluation value 3: Laser light absorptance is less than 30%.
The results are shown in Tables 1 and 2. A rating of 1 is the best, and a rating of 3 is poor.

[Evaluation 2]
According to the findings of the present inventors, the electrical conductivity obtained by using the above-mentioned ingot correlates with the electrical conductivity of the shaped body obtained by the additive manufacturing method. In addition, according to the Wiedemann-Franz law, the thermal conductivity of a metal is proportional to its electrical conductivity. Therefore, by confirming the electrical conductivity, which is easy to measure, the thermal conductivity characteristics can also be evaluated.
Therefore, based on the electrical conductivity determined by the above measurement method, the shaped bodies were graded according to the following criteria.
Evaluation value 1: Electrical conductivity is 80% IACS or more.
Evaluation value 2: Electrical conductivity is 50% IACS or more and less than 80% IACS.
Evaluation value 3: Electrical conductivity is less than 50% IACS.
The results are shown in Tables 1 and 2. A rating of 1 is the best, and a rating of 3 is poor.

The notation "-" in the composition of the Cu-based alloy powder in Tables 1 and 2 means that the corresponding component was not detected.

As shown in Tables 1 and 2, the Cu-based alloy powder of the examples was rated higher than the alloy powder of the comparative example, and the object produced by additive manufacturing using the powder of the examples also had high electrical conductivity, clearly demonstrating the superiority of the object produced by the examples of the present invention.

In Comparative Examples 1 to 4, the amount of Cr was insufficient, resulting in poor laser light absorption and a relatively low relative density of the shaped body.
In Comparative Examples 5 to 8, the total amount of Nd, Gd, Dy, and Y was too small, resulting in poor laser light absorptivity or poor conductivity.
In Comparative Examples 9 and 10, the total amount of Nd, Gd, Dy, and Y was excessive, and the precipitate size was excessively large, resulting in poor conductivity.

Claims (3)

In mass percent,
Cr: 0.10 to 1.00%;
Contains one or more of Nd, Gd, Dy and Y in total in an amount of 0.10 to 5.00%;
The remainder is made of Cu and unavoidable impurities, and the layered manufacturing is performed using a Cu-based alloy powder having a laser light absorption rate of 35 to 53% at a wavelength of 1064 nm .
A shaped body made of a Cu-based alloy having an electrical conductivity of 50 to 86% IACS and a precipitate size of 20 μm or less. A shaped body made of a Cu-based alloy with a precipitate size of 20 μm or less, produced by additive manufacturing using the Cu-based alloy powder according to claim 1, in which the unavoidable impurities Si, P, and S are Si: 0.20% or less, P: 0.100% or less, and S: 0.100% or less. A shaped body made of a Cu-based alloy having a precipitate size of ₂₀ μm ^or less, which is produced by additive manufacturing using the Cu-based alloy powder according to claim 1 or ² , wherein the value of D ₅₀ /TD, which is the ratio of the average particle size D 50 (μm) to the tap density TD ( ^Mg /m ^{3 )} , is 0.2×10 -5 to 20×10 -5 ·m 4 /Mg and the sphericity is 0.80 to 0.95.