Additively manufactured copper alloy object and method for producing additively manufactured copper alloy object

Abstract

This additively manufactured copper alloy object comprises a Cu-Cr-Zr-based alloy, and is characterized in that: the Cu-Cr-Zr-based alloy has a Cr content within a range of 0.5-1.5 mass% and a Zr content within a range of 0.02-0.2 mass%; the density of the manufactured object is not less than 99.1%; and, as a result of measuring the crystal orientation of the same by electron backscatter diffraction, the area ratio of crystals having a plane orientation of {101}±15° in a specific direction is not less than 50%.

Description

Copper alloy laminated body and method for manufacturing copper alloy laminated body

[0001] The present invention relates to a copper alloy additive manufacturing method for a Cu-Cr-Zr alloy. This application claims priority to Japanese Patent Application No. 2024-069800 filed on April 23, 2024, and Japanese Patent Application No. 2024-071826 filed on April 25, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, metal additive manufacturing (metal AM) technology has been put into practical use as a method for manufacturing metal parts with various three-dimensional shapes. This technology primarily uses powder as a raw material and creates products using a metal 3D printer. Major metal AM technologies using metal powder include powder bed fusion (PBF), directed energy deposition (DED), and binder jetting, which use electron beams or laser light. Copper alloys possess many basic properties suitable for industrial applications, such as electrical conductivity, thermal conductivity, mechanical properties, wear resistance, and heat resistance, and are used as materials for various components. For example, Cu-Cr-Zr alloys (e.g., CDA No. C18150), a type of precipitation-hardened copper alloy, have excellent electrical conductivity and strength and are widely used as materials for various components. Therefore, in recent years, attempts have been made in various fields, such as space and electrical component applications, to form components of various shapes using metal AM using copper alloy powder, and there is a growing need for copper and copper alloy components manufactured using metal AM.

[0003] For example, Patent Document 1 proposes a technique for producing an additive manufacturing object by metal AM using a copper alloy powder containing either Cr or Si. Patent Document 2 and Non-Patent Document 1 also propose techniques for producing an additive manufacturing object by metal AM using a copper alloy powder containing Cr and Zr.

[0004] JP 2016-211062 A JP 2019-070169 A

[0005] Bruno Buchmayr et. al., "Laser Powder Bed Fusion-Materials Issues and Optimized Processing Parameters for Tool steels, AlSiMg- and CuCrZr-Alloys", ADVANCED ENGINEERING MATERIALS 2017, 19, No. 4, 1600667.

[0006] Because additive manufacturing (AM) products manufactured by metal AM are used as structural components for a variety of applications, the presence of voids in copper alloy AM products or an inhomogeneous microstructure as a metal material poses problems in terms of thermomechanical and electrical reliability. Currently, the most commonly used manufacturing method for metal AM is laser PBF, and attempts have been made to use it for manufacturing copper and copper alloys.

[0007] When performing additive manufacturing using laser or electron beam irradiation, a thin powder layer is first formed (powder bed), and then the powder bed is locally irradiated with a laser or electron beam to melt and solidify the material. However, copper and copper alloys have a high reflectivity in the visible and infrared regions compared to other metal materials such as iron, titanium, and nickel. This causes unstable melting behavior of copper alloy powder during laser PBF, which tends to generate voids inside the produced additively manufactured object, resulting in a number of issues such as unstable quality of the manufactured object and poor productivity. Therefore, there is a need for improvements in the productivity and quality of copper alloy additively manufactured objects made of copper and copper alloys by laser PBF.

[0008] Furthermore, in copper alloy members made of copper alloys, the properties required of the product vary depending on the intended use, and therefore anisotropy of the mechanical properties may be required depending on the intended use. Here, in conventional copper alloy members, the anisotropy of the mechanical properties was imparted by controlling the crystal orientation of the copper alloy material by adjusting the conditions for plastic processing, such as rolling and extrusion, and the conditions for heat treatment. In copper alloy members made of the above-mentioned copper alloy additive manufacturing product, since they are formed into a shape similar to the final product, it is desired to control the anisotropy of the mechanical properties without performing the above-mentioned plastic processing, such as rolling and extrusion.

[0009] This invention has been made in consideration of the above-mentioned circumstances, and aims to provide a copper alloy additive manufacturing body made of a Cu-Cr-Zr alloy, which has few structural defects such as voids and has a high degree of crystal orientation.

[0010] In order to solve the above-mentioned problems, the present inventors conducted extensive research and found that when a high-purity copper alloy is used as a raw material and subjected to a powdering process, the copper alloy powder as a whole has few impurities and maintains a uniform composition, but when focusing on the surfaces of individual particles in the copper alloy powder, a thin layer is formed on the surface of the copper alloy particles that are irradiated with a laser.The thin layer formed on the surface of the copper alloy particles has a characteristic structure in which, compared to the interior of the bulk copper alloy particles, powder constituent elements that exhibit higher laser absorption than copper are present at a high frequency.The thin layer formed on the surface of the copper alloy particles has a characteristic structure which is spontaneously generated in the direct powdering process from the copper alloy raw material, without undergoing a separate coating process or additional process on the powder.

[0011] In addition to the structural characteristics of the copper alloy particle surface of such copper alloy powder, the copper alloy powder derived from a high-purity copper alloy raw material contains fewer impurities that lead to degassing components, thereby suppressing degassing during melting. It has been discovered that this enables the production of dense copper alloy additive manufacturing bodies while maintaining high thermal, electrical, and mechanical properties. Specifically, when copper alloy powder (Cu-Cr-Zr alloy particles) is produced using a copper alloy ingot containing Cr and Zr with sufficiently reduced impurity levels as a raw material, it is possible to form Cr-containing precipitates (Cr-containing precipitates) on the particle surfaces of the copper alloy powder at the copper crystal grain boundaries and on the copper crystal grain surfaces, and it is also possible to form a Cr compound layer containing these Cr-containing precipitates on the particle surfaces. It has also been discovered that the occurrence of structural defects such as voids can be reduced when this powder is used for additive manufacturing.

[0012] Furthermore, when using the above-mentioned copper alloy powder to manufacture a copper alloy additive manufacturing object by irradiating a specific region of a raw material with laser light, it has been discovered that increasing the energy density of the irradiated laser light suppresses the occurrence of defects such as voids, thereby promoting the formation of a continuous structure and enabling a specific crystal orientation to be strongly oriented in the stacking direction. Although laser light is used as the energy source for manufacturing in this invention, it is believed that similar results will be observed when other energy sources are used.

[0013] The present invention has been made based on the above-mentioned findings, and a copper alloy additive manufacturing product of aspect 1 of the present invention is a copper alloy additive manufacturing product made of a Cu-Cr-Zr alloy, wherein the Cu-Cr-Zr alloy has a Cr content in the range of 0.5 mass % or more and 1.5 mass % or less and a Zr content in the range of 0.02 mass % or more and 0.2 mass % or less, the manufactured product density is 99.1% or more, and as a result of crystal orientation measurement by electron backscatter diffraction, the area ratio of crystals having a plane orientation of {101}±15° in a specific direction is 50% or more.

[0014] According to the copper alloy additive manufacturing body of aspect 1 of the present invention, the copper alloy additive manufacturing body is composed of a Cu-Cr-Zr alloy having a Cr content in the range of 0.5 mass% or more and 1.5 mass% or less and a Zr content in the range of 0.02 mass% or more and 0.2 mass% or less, and therefore has excellent conductivity and strength and can be widely used as a material for various parts.

[0015] Furthermore, since the density of the shaped body is 99.1% or more, there are few structural defects such as voids, and the quality is excellent. In this specification, the shaped body density refers to the packing density in the cross section of the copper alloy shaped body, calculated from the cross-sectional area of ​​the copper alloy shaped body and the area occupied by voids observed in the cross section of the copper alloy shaped body. Furthermore, as a result of measuring the crystal orientation by electron backscatter diffraction, the area ratio of crystals having a plane orientation of {101}±15° in a specific direction is 50% or more, which means that the crystal orientation is highly oriented and the mechanical properties are sufficiently anisotropic.

[0016] A copper alloy additive manufacturing object of Aspect 2 of the present invention is characterized in that the oxygen concentration is 300 ppm by mass or less in the copper alloy additive manufacturing object of Aspect 1. According to the copper alloy additive manufacturing object of Aspect 2 of the present invention, the oxygen concentration is suppressed to 300 ppm by mass or less, and therefore structural defects such as oxygen-induced voids are further reduced, resulting in excellent quality.

[0017] A copper alloy additive manufacturing object according to Aspect 3 of the present invention is characterized in that the sulfur concentration is 6 ppm by mass or less in the copper alloy additive manufacturing object according to Aspect 1 or Aspect 2. Since the sulfur concentration is suppressed to 6 ppm by mass or less in the copper alloy additive manufacturing object according to Aspect 3 of the present invention, sulfur-induced defects are further reduced and the quality is excellent.

[0018] A fourth aspect of the present invention is characterized in that the copper alloy additive manufacturing product according to any one of aspects 1 to 3 has an electrical conductivity of 50% IACS or more. The copper alloy additive manufacturing product of the fourth aspect of the present invention is a Cu-Cr-Zr alloy having a Cr content in the range of 0.5% by mass to 1.5% by mass and a Zr content in the range of 0.02% by mass to 0.2% by mass, and has an electrical conductivity of 50% IACS or more, making it suitable for use as a conductive member.

[0019] Aspect 5 of the present invention is a method for manufacturing a copper alloy additive manufacturing object according to any one of Aspects 1 to 4, characterized in that it comprises the steps of preparing a copper alloy powder for metal AM, forming a powder bed containing the copper alloy powder for metal AM, and solidifying the copper alloy powder for metal AM at a predetermined position in the powder bed to form a manufacturing bed. According to the manufacturing method for a copper alloy additive manufacturing object according to Aspect 5 of the present invention, a copper alloy additive manufacturing object having few structural defects such as voids and excellent quality can be obtained.

[0020] Aspect 6 of the present invention is the method for producing a copper alloy additive manufacturing object according to Aspect 5, characterized in that it comprises an aging heat treatment step in which the copper alloy additive manufacturing object is maintained at a temperature in the range of 400° C. to 800° C. Aspect 7 of the present invention is the method for producing a copper alloy additive manufacturing object according to Aspect 5 or Aspect 6, characterized in that it comprises a solution heat treatment step in which the copper alloy additive manufacturing object is maintained at a temperature in the range of 900° C. to 980° C. According to the method for producing a copper alloy additive manufacturing object according to Aspect 6 or Aspect 7 of the present invention, a copper alloy additive manufacturing object having excellent mechanical properties can be obtained.

[0021] According to the present invention, it is possible to provide a copper alloy additive manufacturing product made of a Cu-Cr-Zr alloy, which has few structural defects such as voids and has a high degree of crystal orientation.

[0022] 1 is a flow diagram of a method for producing a copper alloy additive manufacturing object according to the present embodiment. FIG. 2 is a schematic explanatory diagram of copper alloy particles constituting the copper alloy powder for metal AM used in the present embodiment.

[0023] Hereinafter, a copper alloy additive manufacturing product according to one embodiment of the present invention will be described with reference to the accompanying drawings. The copper alloy additive manufacturing product according to this embodiment is manufactured by additive manufacturing using a copper alloy powder for metal AM made of a Cu-Cr-Zr alloy.

[0024] The copper alloy additive manufacturing object of this embodiment is made of a Cu-Cr-Zr alloy containing a Cr content in the range of 0.5% by mass to 1.5% by mass and a Zr content in the range of 0.02% by mass to 0.2% by mass. The copper alloy additive manufacturing object preferably has a composition consisting of copper and impurities other than Cr and Zr. In other words, the copper alloy additive manufacturing object of this embodiment is made of a copper alloy corresponding to CDA No. C18150.

[0025] In the copper alloy additive manufacturing product, the lower limit of the Cr content is more preferably 0.6% by mass or more, and even more preferably 0.7% by mass or more. The upper limit of the Cr content is more preferably 1.4% by mass or less, and even more preferably 1.3% by mass or less. In the copper alloy additive manufacturing product, the upper limit of the Zr content may be 0.16% by mass or less, more preferably 0.14% by mass or less, and even more preferably 0.12% by mass or less.

[0026] In the copper alloy additive manufacturing product of this embodiment, the alloying elements are Cr and Zr, and the impurities are components containing impurity elements and O, H, S, N, and C. The copper alloy constituting the copper alloy additive manufacturing product of this embodiment may contain additional elements and impurity elements other than the alloying elements (Cr, Zr). In the copper alloy additive manufacturing product, examples of additional elements and impurity elements other than the alloying elements (Cr, Zr) constituting C18150 include one or more selected from Mg, Ti, Ni, Si, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, P, Sb, Fe, Bi, Ag, and S.

[0027] In the copper alloy additive manufacturing product, the total amount of additive elements other than alloy elements and impurity elements (impurities excluding O, H, S, N, and C) is preferably 0.04 mass% or less, more preferably 0.03 mass% or less, even more preferably 0.02 mass% or less, and even more preferably 0.01 mass% or less. In addition, in the copper alloy additive manufacturing product, the upper limit of the content of additive elements other than alloy elements and impurity elements (impurities excluding O, H, S, N, and C) is preferably 30 mass ppm or less, more preferably 20 mass ppm or less, and even more preferably 15 mass ppm or less.

[0028] The copper alloy additive manufacturing product of this embodiment has a density of 99.1% or more. That is, the copper alloy additive manufacturing product of this embodiment has almost no structural defects such as voids. The density of the copper alloy additive manufacturing product of this embodiment is more preferably 99.5% or more, and even more preferably 99.8% or more. The upper limit of the density of the copper alloy additive manufacturing product may be 100%.

[0029] The shaped body density is the packing density in the evaluation cross section of the copper alloy additive manufacturing body, calculated from the area of ​​the evaluation cross section of the copper alloy additive manufacturing body and the area occupied by voids observed in the evaluation cross section of the copper alloy additive manufacturing body using the following formula (1): shaped body density (%) = {(area of ​​evaluation cross section of copper alloy additive manufacturing body - area occupied by voids observed in the evaluation cross section of the copper alloy additive manufacturing body) / (area of ​​evaluation cross section of copper alloy additive manufacturing body)} × 100 (1) The area of ​​the evaluation cross section of the copper alloy additive manufacturing body and the area occupied by voids observed in the evaluation cross section of the copper alloy additive manufacturing body can be detected by observing the evaluation cross section of the copper alloy additive manufacturing body using an optical microscope.

[0030] In the copper alloy additive manufacturing product of this embodiment, as a result of crystal orientation measurement by electron backscatter diffraction, the area ratio of crystals having a plane orientation of {101} ± 15° in a specific direction is 50% or more. In this embodiment, when the measurement surface is a plane perpendicular to the powder stacking direction, the area ratio of crystals having a plane orientation of {101} ± 15° in the stacking direction is 50% or more. In addition to such high orientation, the copper alloy additive manufacturing product may also have an area ratio of crystals having a plane orientation of {101} ± 15° in a predetermined second direction (the A1 direction described below) perpendicular to the specific direction (in this case, the stacking direction or the first direction) of 50% or more. In addition, in the copper alloy additive manufacturing product of this embodiment, as a result of crystal orientation measurement by electron backscatter diffraction, the area ratio of crystals having a plane orientation of {101} ± 15° in at least one specific direction is preferably 60% or more, and more preferably 70% or more. Furthermore, as a result of measuring the crystal orientation by electron backscatter diffraction, the upper limit of the area ratio of crystals having a plane orientation of {101}±15° in at least one specific direction may be 99.9%.

[0031] Crystal orientation measurement by electron backscatter diffraction can be performed as follows. When the powder stacking direction of a copper alloy additive manufacturing object is known, for example, because it is connected to a base plate, a sample coordinate system is defined based on the base plate surface, and the direction perpendicular to the base plate surface (stacking direction) is defined as the A3 direction. Furthermore, based on this A3 direction, the A2 direction is defined as a direction parallel to the sample cross section of EBSD (Electron Backscattered Diffraction) analysis and perpendicular to the A3 direction, and the A1 direction is defined as a direction perpendicular to the sample cross section of EBSD analysis and perpendicular to the A3 direction. When analyzing the orientation density of a specific crystal plane, for example, when analyzing the orientation density in the A3 direction, the percentage of the crystal plane being analyzed that falls within an angle range of ±15° with respect to the A3 direction is used.

[0032] On the other hand, after the copper alloy additive manufacturing product is separated from the base plate as an independent part, the orientation can be analyzed by, for example, analyzing the crystal orientation of the copper alloy additive manufacturing product using the X-ray reflection Laue method. Then, after confirming the orientation with the maximum intensity of the {101} orientation, the orientation density of the {101} orientation within the range of {101}±15° can be confirmed by EBSD analysis. Therefore, the orientation density of the {101} orientation within the range of {101}±15°, i.e., the area fraction of crystals having a plane orientation of {101}±15°, within the measurement area of ​​the sample cross section can be obtained by EBSD analysis.

[0033] Here, according to the literature (Journal of the Society of Materials Science, Japan, Vol. 67, No. 9, pp. 855 (2018)), when the elastic constant and the crystal plane index {hkl} are taken into consideration, the elastic modulus of Cu crystal (FCC crystal) is expressed by the following formula (2).

[0034]

[0035] The above formula and the elastic modulus C of Cu crystal described in the literature (Charles Kittel, Introduction to Solid State Physics - 7th ed., 1996, John Wiley & Sons, Inc. (ISBN 0-471-11181-3)) １１ , C １２ , C ４４ By using this, for example, the Young's modulus E(100) of the (100) plane of a Cu crystal and the Young's modulus E(101) of the (101) plane of the Cu crystal are calculated as follows: E(101) = 131 GPa E(100) = 68 GPa Therefore, in the copper alloy additive manufacturing product of this embodiment, the area ratio of crystals having a plane orientation of {101} ± 15° is 50% or more, and since the crystal planes are highly oriented in one direction (stacking direction), the mechanical properties in this direction are different from those in other directions and the product has anisotropy.

[0036] Furthermore, in the copper alloy additive manufacturing product of this embodiment, if the oxygen concentration is high, structural defects such as voids are likely to occur in the laminate structure. Therefore, in the copper alloy additive manufacturing product of this embodiment, the oxygen concentration is preferably 300 mass ppm or less. The oxygen concentration is more preferably 150 mass ppm or less, and even more preferably 120 mass ppm or less. The lower limit of the oxygen concentration is not particularly limited, but may be 10 mass ppm.

[0037] Furthermore, in the copper alloy additive manufacturing product of this embodiment, if the sulfur concentration is high, structural defects such as voids are more likely to occur in the laminate structure. Therefore, in the copper alloy additive manufacturing product of this embodiment, the sulfur concentration is preferably 6 mass ppm or less. The sulfur concentration is more preferably 4 mass ppm or less, and even more preferably 2 mass ppm or less. The lower limit of the sulfur concentration is not particularly limited, but may be 0.5 mass ppm. Furthermore, in the copper alloy additive manufacturing product of this embodiment, it is preferable that the hydrogen concentration is 3 mass ppm or less, the nitrogen concentration is 1 mass ppm or less, and the carbon concentration is 1 mass ppm or less.

[0038] In a copper alloy additive manufacturing product, the oxygen concentration can be measured by inert gas fusion-infrared absorption, the hydrogen concentration and nitrogen concentration can be measured by inert gas fusion-thermal conductivity, and the sulfur concentration and carbon concentration can be measured by combustion-infrared absorption. The Cr concentration, Zr concentration, and concentrations of additive elements other than alloy elements and impurity elements (impurities excluding O, H, S, N, and C) in a copper alloy additive manufacturing product can be obtained by an appropriate combination of X-ray fluorescence analysis, glow discharge mass spectrometry, and inductively coupled plasma mass spectrometry.

[0039] Furthermore, as described above, the copper alloy additive manufacturing product of this embodiment is composed of a Cu-Cr-Zr alloy, which is a precipitation-strengthened copper alloy, and therefore may be used as a conductive member. Therefore, the copper alloy additive manufacturing product of this embodiment preferably has a conductivity of 40% IACS or higher. The conductivity is more preferably 50% IACS or higher, and even more preferably 60% IACS or higher. The upper limit of the conductivity is not particularly limited, but may be 93% IACS. The conductivity of the copper alloy additive manufacturing product can be obtained by measuring using a vortex conductivity meter.

[0040] Next, a method for manufacturing a copper alloy additive manufacturing object according to this embodiment will be described with reference to the flow diagram of Fig. 1. The method for manufacturing a copper alloy additive manufacturing object shown in Fig. 1 includes a powder preparation step S01 for preparing a copper alloy powder for metal AM, a manufacturing step S02 for manufacturing a copper alloy additive manufacturing object by additive manufacturing the copper alloy powder for metal AM, and a heat treatment step S03.

[0041] (Powder Preparation Step S01) In this powder preparation step S01, a copper alloy powder for metal AM made of a Cu-Cr-Zr alloy is prepared. In the copper alloy powder for metal AM used in this embodiment, a Cr compound layer 52 containing a Cr-containing compound is formed on the particle surface. That is, as shown in FIG. 2, the copper alloy particle 50 of the copper alloy powder for metal AM of this embodiment preferably comprises a particle body 51 made of a copper alloy containing Cr, and a Cr compound layer 52 formed on the outer peripheral surface of the particle body 51.

[0042] Here, the surface (particle surface) of the copper alloy particle constituting the copper alloy powder for metal AM used in this embodiment refers to the region from the outermost surface of the particle to a depth of 100 nm. Furthermore, the thickness of the Cr compound layer 52 on the particle surface of the copper alloy powder for metal AM is preferably 1 nm or more and 100 nm or less.

[0043] The particle body 51 of the copper alloy particle 50 of the copper alloy powder for metal AM used in this embodiment is polycrystalline, and it has been confirmed that a Cr-containing compound consisting of a compound containing Cr is dispersed on the surface of the particle body 51. Note that this Cr-containing compound is dispersed both at the grain boundaries and within the grains. Note that in this embodiment, it is preferable that the particle diameter of the Cr-containing compound present in the Cr compound layer 52 is in the range of 1 nm to 1000 nm.

[0044] In the copper alloy particle 50 of the copper alloy powder for metal AM used in this embodiment, cross-sectional observation shows that Cr-containing compounds consisting of compounds containing Cr are dispersed at the grain boundaries inside the particle body 51. Note that in this embodiment, as a result of cross-sectional observation of the particle, it is preferable that the particle diameter of the Cr-containing compounds observed at the grain boundaries inside the particle body 51 is in the range of 1 nm or more and 1000 nm or less.

[0045] In the copper alloy particles 50 of the copper alloy powder for metal AM used in this embodiment, it is preferable that the Zr-containing compound is distributed on the surface of the particle body 51. Furthermore, in cross-sectional observation of the copper alloy particle 50, it is preferable that the Zr-containing compound is distributed at the crystal grain boundaries inside the particle body 51.

[0046] In the copper alloy powder for metal AM used in this embodiment, it is preferable that the volume-based 50% cumulative particle diameter D50 measured by a laser diffraction / scattering method is in the range of 10 μm or more and 120 μm or less, the 10% cumulative particle diameter D10 is in the range of 1 μm or more and 80 μm or less, and the 90% cumulative particle diameter D90 is in the range of 10 μm or more and 150 μm or less.

[0047] The copper alloy powder for metal AM used in this embodiment is produced by producing a high-purity copper alloy ingot with few impurities using a continuous melting and casting apparatus, processing this copper alloy ingot into a wire rod and cutting it to form a copper alloy raw material, and atomizing this copper alloy raw material. Here, in the copper alloy ingot produced by the continuous melting and casting apparatus, the O concentration is preferably 10 mass ppm or less, the H concentration is 5 mass ppm or less, the S concentration is 15 mass ppm or less, and the total content of impurity elements other than Cu (excluding O, H, and S) is preferably 0.04 mass% or less. Furthermore, in the above-mentioned copper alloy raw material, the O concentration is preferably 10 mass ppm or less, the H concentration is 5 mass ppm or less, the S concentration is 15 mass ppm or less, and the total content of impurity elements other than Cu and alloy elements (excluding O, H, and S) is preferably 0.04 mass% or less.

[0048] In the copper alloy powder for metal AM used in this embodiment, it is preferable that the O concentration is 1000 mass ppm or less, the H concentration is 5 mass ppm or less, the S concentration is 10 mass ppm or less, and the N concentration is 10 mass ppm or less. In the copper alloy powder for metal AM, the total amount of additive elements other than alloy elements and impurity elements (impurities excluding O, H, S, N, and C) may be 0.07 mass% or less, 0.06 mass% or less, or 0.05 mass% or less, preferably 0.04 mass% or less, more preferably 0.03 mass% or less, even more preferably 0.02 mass% or less, and even more preferably 0.01 mass% or less. In addition, in the copper alloy powder for metal AM, the upper limit of the content of each of additive elements other than alloy elements and impurity elements (impurities excluding O, H, S, N, and C) is preferably 30 mass ppm or less, more preferably 20 mass ppm or less, and even more preferably 15 mass ppm or less.

[0049] In the copper alloy powder for metal AM of this embodiment, the alloying elements are Cr and Zr, and the impurities are components containing the impurity elements as well as O, H, S, N, and C. Furthermore, the copper alloy constituting the copper alloy powder for metal AM of this embodiment may contain additive elements and impurity elements other than the alloying elements (Cr, Zr). In the copper alloy powder for metal AM, additive elements and impurity elements other than the alloying elements (Cr, Zr) constituting C18150 can include, for example, one or more selected from Mg, Ti, Ni, Si, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, P, Sb, Fe, Bi, Ag, S, and the like.

[0050] In this embodiment, as described above, the atomization process is performed using a molten alloy with a sufficiently reduced impurity content, which prevents alloy elements such as Cr and Zr from reacting with the impurities and consuming them, making it possible to produce Cr-containing compounds and Zr-containing compounds. During this atomization process, sufficient vacuuming and atmospheric control using gases can be performed, making it possible to produce higher quality copper alloy powder for metal AM.

[0051] (Shaping process S02) In this shaping process S02, a copper alloy laminate shaped body is produced by sequentially repeating a powder bed formation process S21 in which a powder bed containing the above-mentioned copper alloy powder for metal AM is formed, and a shaping bed formation process S22 in which the copper alloy powder for metal AM is solidified at a predetermined position in the powder bed to form a shaping bed.

[0052] In the building bed formation step S22, a laser is used to solidify the copper alloy powder for metal AM. By setting the laser energy density high, the degree of orientation of crystals with a plane orientation of {101}±15° in the stacking direction increases. Therefore, in this embodiment, the laser energy density in the building bed formation step S22 is set to 500 J / mm ３ It is preferable that the value is 600 J / mm or more. ３ In this embodiment, the energy density of the laser in the building bed forming step S22 is set to 700 J / mm ３ It may be 750 J / mm or more.３ It may be more than that.

[0053] (Heat Treatment Step S03) Next, if necessary, heat treatment is performed to appropriately precipitate precipitates, thereby improving electrical conductivity and strength. Here, the heat treatment may include solution heat treatment and aging heat treatment. The solution heat treatment is preferably performed under the conditions of a heat treatment temperature of 900°C or higher and 980°C or lower, and a holding time at the heat treatment temperature of 0.1 hours or higher and 2 hours or lower. The aging heat treatment is preferably performed under the conditions of a heat treatment temperature of 400°C or higher and 800°C or lower, and a holding time at the heat treatment temperature of 1 hour or higher and 3 hours or lower. Note that if solution treatment has progressed sufficiently in the shaping step S02, the solution heat treatment may be omitted and only aging heat treatment may be performed directly. Note that if solution treatment has progressed sufficiently in the shaping step S02, the heat treatment step S03 may be omitted.

[0054] The copper alloy additive manufacturing object of this embodiment is manufactured by the various steps described above.

[0055] The copper alloy additive manufacturing body of this embodiment, configured as described above, is made of a Cu-Cr-Zr alloy with a Cr content in the range of 0.5 mass% or more and 1.5 mass% or less and a Zr content in the range of 0.02 mass% or more and 0.2 mass% or less, and therefore has excellent conductivity and strength, and can be widely used as a material for various parts.

[0056] Furthermore, in the copper alloy additive manufacturing product of this embodiment, the density of the manufactured product is 99.1% or more, so there are few structural defects such as voids, and the quality is excellent. Furthermore, in the copper alloy additive manufacturing product of this embodiment, as a result of crystal orientation measurement by electron backscatter diffraction (EBSD), the area ratio of crystals having a plane orientation of {101}±15° in a specific direction (in this embodiment, the stacking direction) is 50% or more, which means that the crystal orientation is highly oriented and the mechanical properties are sufficiently anisotropic. Therefore, the copper alloy additive manufacturing product of this embodiment is particularly suitable as a copper alloy part for applications requiring anisotropy in mechanical properties.

[0057] Furthermore, in the copper alloy additive manufacturing product of this embodiment, when the oxygen concentration is 300 ppm by mass or less, the structural defects caused by oxygen are further reduced, resulting in excellent quality. Furthermore, in the copper alloy additive manufacturing product of this embodiment, when the sulfur concentration is 6 ppm by mass or less, the structural defects caused by sulfur are further reduced, resulting in excellent quality. Furthermore, in the copper alloy additive manufacturing product of this embodiment, when the electrical conductivity is 50% IACS or more, this copper alloy additive manufacturing product can be suitably used as a conductive member.

[0058] The above describes a copper alloy additive manufacturing body and a method for manufacturing a copper alloy additive manufacturing body that are embodiments of the present invention, but the present invention is not limited to this and can be modified as appropriate within the scope of the technical concept of the invention.

[0059] The results of confirmation experiments conducted to confirm the effects of the present invention will be described below.

[0060] (Test 1) A copper raw material made of 4N-grade high-purity copper was prepared, and a C18150 copper alloy ingot was produced using a continuous melting and casting apparatus. At this time, the O concentration was 10 mass ppm or less, the H concentration was 5 mass ppm or less, the S concentration was 15 mass ppm or less, and the total content of impurity elements other than Cu (excluding O, H, and S) was 0.04 mass% or less. Next, using the produced copper alloy ingot of C18150 composition as a raw material, a copper alloy powder for metal AM was produced by a gas atomization method using argon gas, and the powder was classified to a particle size suitable for the powder bed of laser PBF, thereby obtaining a copper alloy powder for metal AM of Example 1 of the present invention. The copper alloy powder for metal AM of Example 1 was subjected to particle size distribution measurement using an MT3300EXII manufactured by Microtrac Co., Ltd., and the particle size distribution was as follows: 10% cumulative particle size on a volume basis was 14 μm, 50% cumulative particle size was 31 μm, and 90% cumulative particle size was 52 μm. The component composition of this copper alloy powder for metal AM is shown in Table 1.

[0061] Using the copper alloy powder for metal AM described above, an additive manufacturing object was produced using a commercially available laser PBF printer. The light source was a 400 W Yb fiber laser, and the laser spot diameter was approximately 100 μm. The laser energy density during manufacturing was 90 to 1541 J / mm.３ In this manner, a copper alloy additive manufacturing product of Inventive Example 1 was obtained. The composition of the copper alloy additive manufacturing product of Inventive Example 1 is shown in Table 1.

[0062] Additionally, a commercially available copper alloy powder for metal AM with a C18150 composition was prepared. The composition of this copper alloy powder is shown in Comparative Example 1 in Table 1. The commercially available copper alloy powder for metal AM with a C18150 composition has high O concentration, H concentration, S concentration, and content of impurity elements other than Cu (excluding O, H, and S). Using this copper alloy powder, an additive manufacturing object was produced using a commercially available laser PBF printer. The light source was a 400 W Yb fiber laser, and the laser spot diameter was approximately 100 μm. The laser energy density during manufacturing was 90 to 1541 J / mm ３ The conditions were as follows. In this manner, a copper alloy additive manufacturing object of Comparative Example 1 was obtained. The composition of the copper alloy additive manufacturing object of Comparative Example 1 is shown in Table 1.

[0063] The O concentration in the copper alloy powder (copper alloy powder for metal AM) and copper alloy additive manufacturing body shown in Table 1 was determined by inert gas fusion-infrared absorption spectrometry, the H concentration and N concentration by inert gas fusion-thermal conductivity spectrometry, and the S concentration and C concentration by combustion-infrared absorption spectrometry. The concentrations of components other than copper were determined by an appropriate combination of X-ray fluorescence spectrometry, glow discharge mass spectrometry, and inductively coupled plasma mass spectrometry.

[0064]

[0065] As shown in Table 1, it was confirmed that the copper alloy additive manufacturing body and copper alloy powder for metal AM of Example 1 of the present invention had lower impurity contents and lower O and S contents than the copper alloy additive manufacturing body and copper alloy powder of Comparative Example 1. Furthermore, in Example 1 of the present invention, both the copper alloy powder for metal AM and the copper alloy additive manufacturing body had a C18150 composition, and the contents of alloy elements (Cr, Zr) did not change significantly. On the other hand, it was confirmed that the carbon concentration of the copper alloy additive manufacturing body was reduced from the carbon concentration of the copper alloy powder for metal AM. It is presumed that C (carbon) was removed during the process of melting the copper alloy powder for metal AM by laser PBF.

[0066] The crystal orientation characteristics of the copper alloy laminated shaped body of Example 1 described above were evaluated using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) (hereinafter abbreviated as EBSD). For the evaluation using the EBSD method, a Quanta FEG 450 manufactured by FEI, OIM Data Collection manufactured by EDAX TSL, and analysis software (OIM Data Analysis ver. 5.3 manufactured by EDAX TSL) were used. The acceleration voltage of the electron beam for EBSD analysis was 20 kV, the measurement interval was 0.1 μm steps, and the measurement area was 800 μm × 1200 μm. The crystal orientation of each crystal grain in the cross section of the shaped body was analyzed.

[0067] When the base plate of the copper alloy additive manufacturing sample is the bottom surface of the sample, additive manufacturing is performed vertically upward from the base plate surface, and this direction is defined as the building direction (BD). Here, the A3 direction corresponds to the BD direction. Using the A3 direction as a reference, the A2 direction is defined as a direction parallel to the sample cross section for EBSD analysis and perpendicular to the A3 direction, and the A1 direction is defined as a direction perpendicular to the sample cross section for EBSD analysis and perpendicular to the A3 direction.

[0068] Next, assuming that the allowable range of deviation angles of the designated crystal plane directions of the copper crystal from the coordinate axis direction of each sample was 0 to 15 degrees, the area occupancy (crystal area ratio) of crystal grains having the orientation characteristics of the designated crystal planes within this allowable angle range was calculated on the measured cross section of the sample. Here, the area occupancy of crystal grains was calculated by integrating the areas of crystal grains having the orientation characteristics of each designated crystal plane within a measurement area of ​​800 μm × 1200 μm on the cross section of each sample. Since this area occupancy indicates the orientation characteristics of each designated crystal plane, in the present invention, this area occupancy was used to calculate the orientation degree of a certain designated crystal plane direction.

[0069]

[0070] It was confirmed that the copper alloy additive manufacturing product of Inventive Example 1 exhibited a high degree of orientation in all directions, A1, A2, and A3. In particular, it was confirmed that the copper alloy additive manufacturing product of Inventive Example 1 exhibited a very high degree of orientation in the A3 direction, with the area ratio of crystals having a plane orientation of {101}±15° being 50% or more.

[0071] (Test 2) Next, the copper alloy powder for metal AM used in producing the copper alloy additive manufacturing object of Inventive Example 1 described above was prepared, and the laser energy density during manufacturing was varied to produce copper alloy additive manufacturing objects of Inventive Examples 2 and 3 and Comparative Examples 2 and 3. The crystal orientation characteristics (degree of orientation of crystal orientation) of the obtained copper alloy additive manufacturing objects of Inventive Examples 2 and 3 and Comparative Examples 2 and 3 were evaluated using the area occupancy rate of crystal grains (area rate of crystals), as in Inventive Example 1. The evaluation results are shown in Table 3. Table 3 lists only the {101} orientation in the A1 direction, the {100} orientation in the A2 direction, and the {101} orientation in the A3 direction.

[0072] The packing density of the copper alloy additive manufacturing bodies of Examples 2 and 3 of the present invention and Comparative Examples 2 and 3 was evaluated as follows. The packing density of the evaluation cross section of the copper alloy additive manufacturing body was evaluated from the area of ​​the evaluation cross section of the copper alloy additive manufacturing body and the area occupied by voids observed in the evaluation cross section of the copper alloy additive manufacturing body. Specifically, the cross section of the copper alloy additive manufacturing body was subjected to machining including mirror polishing, and then the evaluation cross section of the copper alloy additive manufacturing body was observed using an optical microscope to confirm the location of voids inside the evaluation cross section to be measured. The area occupied by voids in the evaluation cross section was calculated, and the density of the manufactured body was determined using formula (1). The evaluation results of the manufactured body density are shown in Table 3. Manufactured body density (%) = {(area of ​​evaluation cross section of copper alloy additive manufacturing body - area occupied by voids observed in the evaluation cross section of the copper alloy additive manufacturing body) / (area of ​​evaluation cross section of copper alloy additive manufacturing body)} × 100 (1)

[0073]

[0074] As shown in Table 3, the laser energy density was set to 1027 J / mm ３ and Example 2 of the present invention, which was 770 J / mm ３In Example 3 of the present invention, a high degree of orientation was confirmed in all directions, including the A1, A2, and A3 directions. In particular, the copper alloy additive manufacturing bodies of Examples 2 and 3 of the present invention were confirmed to exhibit a very high degree of orientation in the A3 direction, with the area ratio of crystals having a plane orientation of {101}±15° being 97% or more. Furthermore, the density of the copper alloy additive manufacturing bodies of Examples 2 and 3 of the present invention was higher than that of the copper alloy additive manufacturing bodies of Comparative Examples 2 and 3, approaching 100%, confirming that there were almost no structural defects such as voids and that the quality was excellent.

[0075] (Test 3) Next, 770 J / mm ３ The copper alloy additive manufacturing body of Example 1 of the present invention, which was produced under the conditions shown in Table 4, was subjected to heat treatment under the conditions shown in Table 4, and the electrical conductivity, 0.2% proof stress, and tensile strength were measured. Tensile test specimens were produced with the longitudinal direction perpendicular to the lamination direction, and the tensile strength was measured in the longitudinal direction of the specimen. The measurement results are shown in Table 4. The electrical conductivity was measured at room temperature using a vortex conductivity measurement. The 0.2% proof stress and tensile strength were measured by conducting a tensile test at room temperature according to the ASTM E8 / E8M-22 standard. Furthermore, a tensile strength of 256 J / mm ３ to 1027 J / mm ３ The copper alloy additive manufacturing object of Example 1 of the present invention, produced under the conditions shown in Table 5, was subjected to heat treatment under the conditions shown in Table 5, and its Vickers hardness (HV unit) was measured at room temperature. The density of the produced copper alloy additive manufacturing object exceeded 99.1%, and the density was sufficient for evaluating Vickers hardness. The measurement results are shown in Table 5. The Vickers hardness was measured in accordance with JIS Z 2244.

[0076]

[0077]

[0078] Furthermore, as shown in Table 4, it was confirmed that by appropriately performing solution heat treatment and aging heat treatment, it is possible to obtain a copper alloy laminate with increased electrical conductivity and excellent mechanical properties and electrical conductivity. It was also confirmed that by performing direct aging heat treatment without solution heat treatment after producing a copper alloy additive manufacturing body, it is possible to improve mechanical strength and electrical conductivity. Furthermore, as shown in Table 5, it was confirmed that the Vickers hardness can be adjusted by combining solution heat treatment and aging heat treatment or adjusting the heat treatment conditions of direct aging heat treatment.

[0079] From the above, it has been confirmed that the present invention can provide a copper alloy additive manufacturing body made of a Cu-Cr-Zr alloy, which has few structural defects such as voids and has a high degree of crystal orientation.

Claims

1. A copper alloy additive manufacturing object made of a Cu-Cr-Zr alloy, wherein the Cu-Cr-Zr alloy has a Cr content in the range of 0.5% by mass or more and 1.5% by mass or less and a Zr content in the range of 0.02% by mass or more and 0.2% by mass or less, the density of the manufactured object is 99.1% or more, and as a result of crystal orientation measurement by electron backscatter diffraction, the area ratio of crystals having a plane orientation of {101}±15° in a specific direction is 50% or more.

2. The copper alloy additive manufacturing body according to claim 1, characterized in that the oxygen concentration is 300 mass ppm or less.

3. The copper alloy additive manufacturing body according to claim 1, characterized in that the sulfur concentration is 6 mass ppm or less.

4. The copper alloy additive manufacturing product according to claim 1, characterized in that the electrical conductivity is 50% IACS or more.

5. A method for manufacturing a copper alloy additive manufacturing body according to claim 1, comprising: a step of preparing copper alloy powder for metal AM; a powder bed formation step of forming a powder bed containing said copper alloy powder for metal AM; and a shaping bed formation step of solidifying said copper alloy powder for metal AM at a predetermined position in said powder bed to form a shaping bed.

6. The method for producing a copper alloy additive manufacturing body according to claim 5, further comprising an aging heat treatment step in which the copper alloy additive manufacturing body is maintained at a temperature in the range of 400°C or higher and 800°C or lower.

7. A method for producing a copper alloy laminated shaped body according to claim 5 or claim 6, comprising a solution heat treatment process in which the copper alloy laminated shaped body is maintained at a temperature in the range of 900°C or higher and 980°C or lower.

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