Copper alloy additive manufacturing structure, and method for manufacturing a copper alloy additive manufacturing structure.

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

[Technical Field]

[0001] The present invention relates to a copper alloy additively fabricated structure made of a Cu-Cr-Zr alloy, and a method for manufacturing the copper alloy additively fabricated structure. This application claims priority based on Japanese Patent Application No. 2024-069800, filed in Japan on April 23, 2024, and Japanese Patent Application No. 2024-071826, filed in Japan on April 25, 2024, and the contents thereof are incorporated herein by reference. [Background technology]

[0002] In recent years, metal additive manufacturing (AM) technology, which primarily uses powder as a raw material and creates products with metal 3D printers, has been put into practical use as a method for manufacturing metal parts with various three-dimensional shapes. 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 numerous fundamental properties suitable for industrial applications, including 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 (such as CDA No. C18150), a type of precipitation-hardening copper alloy, exhibit excellent electrical conductivity and strength, and are widely used as materials for various parts. Therefore, in recent years, in various fields such as space and electrical component applications, attempts have been made to form components of various shapes using metal additive manufacturing (AM) with copper alloy powder, and the demand for copper and copper alloy parts manufactured by metal AM is increasing.

[0003] For example, Patent Document 1 proposes a technique for creating additively fabricated bodies using metal additive manufacturing (AM) with copper alloy powder containing either Cr or Si. Furthermore, Patent Document 2 and Non-Patent Document 1 propose a technique for creating additively fabricated objects using metal additive manufacturing (AM) with copper alloy powder containing Cr and Zr. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-211062 [Patent Document 2] Japanese Patent Publication No. 2019-070169 [Non-patent literature]

[0005] [Non-Patent Document 1] 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. [Overview of the project] [Problems that the invention aims to solve]

[0006] Since additively fabricated bodies created using metal additive manufacturing (AM) are used as structural components in various applications, the presence of voids within copper alloy additively fabricated bodies or the non-uniformity of the microstructure of the metallic material can pose problems in terms of thermomechanical and electrical reliability. Currently, the most widely used additive manufacturing method for metals is laser photoblasting (PBF), and laser PBF is also being attempted for copper and copper alloys.

[0007] Incidentally, when performing additive manufacturing using laser light or electron beam irradiation, a thin layer of powder is first formed (powder bed), and then the material is melted and solidified by locally irradiating this powder bed with a laser or electron beam. However, copper and copper alloys have a higher reflectivity to visible and infrared light compared to other metallic materials such as iron, titanium, and nickel. This causes the melting behavior of copper alloy powder to become unstable during the laser PBF process, making it easy for voids to form inside the manufactured additively fabricated object. As a result, there are numerous problems such as unstable quality and poor productivity of objects manufactured by laser PBF. Therefore, there is a growing need to improve the productivity and quality of copper alloy additively fabricated objects made of copper and copper alloys manufactured by laser PBF.

[0008] Furthermore, in copper alloy components, the required properties of the product vary depending on the intended use, and therefore, anisotropy of mechanical properties may be required depending on the application. In conventional copper alloy components, anisotropy of mechanical properties was imparted by controlling the orientation of the crystal orientation of the copper alloy material by adjusting the plastic deformation conditions such as rolling and extrusion, as well as the heat treatment conditions. In copper alloy components made from the aforementioned copper alloy additively fabricated bodies, since they are formed in a shape that approximates the final product, it is necessary to control the anisotropy of their mechanical properties without performing plastic processing such as rolling and extrusion as described above.

[0009] This invention has been made in view of the circumstances described above, and aims to provide a copper alloy additively fabricated body made of a Cu-Cr-Zr alloy, having few structural defects such as voids, and possessing high crystal orientation. [Means for solving the problem]

[0010] To solve the above-mentioned problems, the inventors conducted diligent research and found that when a high-purity copper alloy is used as a raw material and subjected to powdering, the copper alloy powder as a whole maintains a low level of impurities and a uniform composition. However, when focusing on the surface 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. In this thin layer formed on the surface of the copper alloy particles, a characteristic structure is found in which powder constituent elements that exhibit higher laser absorption than copper are present at a high frequency compared to the inside of the bulk copper alloy particles. This structure is spontaneously generated in the direct powdering process from the copper alloy raw material, without the need for individual coating processes or additional processes on the powder.

[0011] In addition to the structural characteristics of the copper alloy particle surface of such copper alloy powder, we found that because the copper alloy powder is derived from high-purity copper alloy raw materials, it contains fewer impurities that lead to degassing, thereby suppressing degassing during melting. This allows for the manufacture of dense copper alloy additive structures with high thermal, electrical, and mechanical properties. Specifically, it was found that when copper alloy powder (Cu-Cr-Zr alloy particles) is produced using copper alloy ingots containing Cr and Zr with sufficiently reduced impurity levels as raw materials, Cr-containing precipitates (Cr-containing precipitates) can be formed on the particle surface of the copper alloy powder at the copper grain boundaries and on the copper grain surfaces, and a Cr compound layer containing these Cr-containing precipitates can also be formed on the particle surface. Furthermore, it was found that when additive manufacturing is performed using this powder, the occurrence of structural defects such as voids can be reduced.

[0012] Furthermore, we have found that when manufacturing a copper alloy additive body using the aforementioned copper alloy powder by irradiating a specific region of the raw material with laser light, increasing the energy density of the irradiated laser light suppresses the generation of defects such as voids, thereby promoting the formation of a continuous structure and making it possible to strongly orient a specific crystal orientation in the layering direction. In this invention, laser light was used as the energy source for fabrication, but it is thought that similar results can be observed when other energy sources are used.

[0013] The present invention has been made based on the above findings. The copper alloy laminated body of Aspect 1 of the present invention is a copper alloy laminated body made of a Cu-Cr-Zr alloy. The Cu-Cr-Zr alloy has a Cr content within the range of 0.5 mass% or more and 1.5 mass% or less, and a Zr content within the range of 0.02 mass% or more and 0.2 mass% or less. The sulfur concentration is 6 mass ppm or less, The total amount of additive elements and impurity elements other than the alloying elements in the Cu-Cr-Zr alloy is 0.04% by mass or less. the density of the shaped body is 99.1% or more, In the sample cross-section of the copper alloy additive body As a result of measuring the crystal orientation by electron backscatter diffraction, Powder layering direction in which the area ratio of crystals having a plane orientation of {101} ± 15° In the above sample cross-section is 50% or more.

[0014] According to the copper alloy laminated body of Aspect 1 of the present invention, since it is composed of a Cu-Cr-Zr alloy in which the Cr content is within the range of 0.5 mass% or more and 1.5 mass% or less, and the Zr content is within the range of 0.02 mass% or more and 0.2 mass% or less, it has excellent conductivity and strength and can be widely applied as a material for various parts. Because the sulfur concentration is kept below 6 massppm, there are even fewer sulfur-related defects, resulting in superior quality.

[0015] Also, 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 density of the shaped body is the filling density in the cross section of the copper alloy laminated body calculated from the area of the cross section of the copper alloy laminated body and the area occupied by the voids observed in the cross section of the copper alloy laminated body. And as a result of measuring the crystal orientation by electron backscatter diffraction, since the area ratio of crystals having a plane orientation of {101} ± 15° in a specific direction is 50% or more, the crystal orientation is highly oriented, and it has sufficient anisotropy in mechanical properties.

[0016] The copper alloy laminated body of Aspect 2 of the present invention is characterized in that, in the copper alloy laminated body of Aspect 1, the oxygen concentration is 300 mass ppm or less. According to the copper alloy additive fabricated body of embodiment 2 of the present invention, since the oxygen concentration is kept below 300 mass sppm, structural defects such as oxygen-induced voids are further reduced, resulting in superior quality. The copper alloy additive body of embodiment 3 of the present invention is characterized in that, in the copper alloy additive body of embodiment 1 or embodiment 2, the additive elements and impurity elements other than the alloying elements are one or more selected from Mg, Ti, Ni, Si, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, P, Sb, Bi, Ag, and S.

[0018] Aspect 4 of the present invention is characterized in that, in any one of the copper alloy additive fabricated bodies of aspects 1 to 3, the conductivity is 50% IACS or higher. According to the copper alloy additive fabricated body of embodiment 4 of the present invention, 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, and has an electrical conductivity of 50% IACS or more, so it can be suitably used as a conductive member.

[0019] Aspect 5 of the present invention is a method for manufacturing a copper alloy additive body according to any one of aspects 1 to 4, characterized by comprising: a step of preparing copper alloy powder for metal AM; a powder bed forming step of forming a powder bed containing the copper alloy powder for metal AM; and a build bed forming step of solidifying the copper alloy powder at predetermined positions in the powder bed to form a build bed. According to the method for manufacturing a copper alloy additively fabricated body of aspect 5 of the present invention, a copper alloy additively fabricated body with fewer structural defects such as voids and superior quality can be obtained.

[0020] Aspect 6 of the present invention is a method for manufacturing a copper alloy additive body as described in Aspect 5, characterized in that it comprises an aging heat treatment step of holding the copper alloy additive body in a temperature range of 400°C to 800°C. Aspect 7 of the present invention is a method for manufacturing a copper alloy additive body according to aspect 5 or aspect 6, characterized in that it comprises a solution heat treatment step of holding the copper alloy additive body in a temperature range of 900°C to 980°C. According to the method for manufacturing a copper alloy additively fabricated structure of embodiment 6 or 7 of the present invention, a copper alloy additively fabricated structure with excellent mechanical properties can be obtained. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a copper alloy additively fabricated body made of a Cu-Cr-Zr alloy, which has few structural defects such as voids and has high crystal orientation. [Brief explanation of the drawing]

[0022] [Figure 1] This is a flowchart of the manufacturing method for the copper alloy additive body according to this embodiment. [Figure 2] This is a schematic diagram illustrating the copper alloy particles that make up the copper alloy powder for metal additive manufacturing used in this embodiment. [Modes for carrying out the invention]

[0023] The following describes a copper alloy additive manufacturing body, which is one embodiment of the present invention, with reference to the attached drawings. The copper alloy additively fabricated body in this embodiment is manufactured using copper alloy powder for metal additive manufacturing, which consists of a Cu-Cr-Zr alloy.

[0024] The copper alloy additive manufacturing body of this embodiment is composed of a Cu-Cr-Zr alloy containing Cr in the range of 0.5% to 1.5% by mass and Zr in the range of 0.02% to 0.2% by mass. Preferably, the copper alloy additive manufacturing body has a composition in which the other components besides Cr and Zr consist of copper and impurities. That is, the copper alloy additive manufacturing body of this embodiment is composed of a copper alloy corresponding to CDA No. C18150.

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

[0026] In the copper alloy additive manufacturing body of this embodiment, the alloying elements are Cr and Zr, and the impurities are components including impurity elements and O, H, S, N, and C. Furthermore, the copper alloy constituting the copper alloy additive manufacturing body of this embodiment may also contain additive elements other than the alloying elements (Cr and Zr) and impurity elements. Examples of additive elements and impurity elements other than the alloying elements (Cr and Zr) constituting C18150 in the copper alloy additive manufacturing body 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 copper alloy additive manufacturing, the total amount of additive elements other than alloying elements and impurity elements (excluding O, H, S, N, and C from impurities) 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. Furthermore, in copper alloy additively fabricated bodies, the upper limits of the content of additive elements other than alloying elements and impurity elements (excluding O, H, S, N, and C from impurities) are preferably 30 masssppm or less, more preferably 20 masssppm or less, and even more preferably 15 masssppm or less.

[0028] Furthermore, in the copper alloy additive manufactured body of this embodiment, the material density is set to 99.1% or higher. In other words, in the copper alloy additive manufactured body of this embodiment, there are virtually no structural defects such as voids. Furthermore, the build density of the copper alloy additively fabricated body in this embodiment is more preferably 99.5% or higher, and more preferably 99.8% or higher. The upper limit of the build density may be 100%.

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

[0030] Furthermore, in the copper alloy additively fabricated body of this embodiment, the area ratio of crystals having a plane orientation of {10¹}±15° in a specific direction is 50% or more, as a result of crystal orientation measurement by electron backscatter diffraction. In this embodiment, when the plane perpendicular to the layering direction of the powder is used as the measurement plane, the area ratio of crystals having a plane orientation of {10¹}±15° in the layering direction is 50% or more. In addition, the copper alloy additively fabricated body may also have an area ratio of 50% or more of crystals having a plane orientation of {10¹}±15° in a predetermined second direction (direction A1 described later) perpendicular to the above-mentioned specific direction (in this case, the layering direction or the first direction). Furthermore, in the copper alloy additively fabricated body of this embodiment, it is more preferable that the area ratio of crystals having a plane orientation of {10¹}±15° in at least one specific direction is 60% or more, and more preferable that it is 70% or more, based on the results of crystal orientation measurement by electron backscatter diffraction. Furthermore, based on the results of crystal orientation measurements by electron backscatter diffraction, the upper limit of the area fraction of crystals having a plane orientation of {10¹}±15° in at least one specific direction may be 99.9%.

[0031] Crystal orientation can be measured by electron backscatter diffraction as follows. If the layering direction of the copper alloy additively fabricated body is known, such as by its connection to the base plate, the sample coordinate system is defined with respect to the base plate surface, and the direction perpendicular to the base plate surface (layering direction) is defined as direction A3. Furthermore, using this A3 direction as a reference, direction A2 is defined as the direction parallel to the sample cross-section for EBSD (Electron Back Scattered Diffraction) analysis and perpendicular to direction A3, and direction A1 is defined as the direction perpendicular to the sample cross-section for EBSD analysis and perpendicular to direction A3. Regarding the analysis of orientation density of a specific crystal plane, for example, in the case of analyzing the orientation density in the A3 direction, it represents the proportion of the crystal plane being analyzed that falls within an angle range of ±15° with respect to the A3 direction.

[0032] On the other hand, after the copper alloy additively fabricated body is separated from the base plate as an independent part, its orientation can be analyzed, for example, by analyzing the crystal orientation of the copper alloy additively fabricated body using the X-ray reflection Laue method. Then, after identifying the orientation with the maximum intensity of {101} orientation, EBSD analysis can be used to determine the orientation density of {101} orientations that falls within the range of {101} ± 15°. Therefore, EBSD analysis provides the orientation density of {10¹} orientations within the {10¹} ± 15° range within the measurement area of ​​the sample cross-section, i.e., the area ratio of crystals with a {10¹} ± 15° plane orientation.

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

[0034]

number

[0035] The above formula and the elastic modulus C of the Cu crystal described in the reference (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 method, for example, the Young's modulus E(100) of the (100) plane and the Young's modulus E(101) of the (101) plane of a Cu crystal can be calculated as follows. E(10¹) = 131 GPa E(100) = 68 GPa Therefore, in the copper alloy additively fabricated body 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 (the stacking direction), the mechanical properties in this direction will differ from those in other directions, resulting in anisotropy.

[0036] Furthermore, in the copper alloy additive fabricated body of this embodiment, when the oxygen concentration increases, structural defects such as voids are more likely to occur in the layered structure. Therefore, in the copper alloy additive manufactured body of this embodiment, it is preferable that the oxygen concentration is 300 mass sppm or less. Furthermore, the oxygen concentration is more preferably 150 massp / pm or less, and more preferably 120 massp / pm or less. The lower limit of the oxygen concentration is not particularly limited, but may be 10 massp / pm.

[0037] Furthermore, in the copper alloy additive fabricated body of this embodiment, as the sulfur concentration increases, structural defects such as voids are more likely to occur in the additive structure. Therefore, in the copper alloy additive body of this embodiment, it is preferable that the sulfur concentration is 6 mas sppm or less. Furthermore, the sulfur concentration is more preferably 4 massppm or less, and more preferably 2 massppm or less. The lower limit of the sulfur concentration is not particularly limited, but may be 0.5 massppm. Furthermore, in the copper alloy additively fabricated body of this embodiment, it is preferable that the hydrogen concentration is 3 massppm or less, the nitrogen concentration is 1 massppm or less, and the carbon concentration is 1 massppm or less.

[0038] In copper alloy additively fabricated structures, oxygen concentration can be obtained by inert gas fusion-infrared absorption spectroscopy, hydrogen and nitrogen concentrations by inert gas fusion-thermal conductivity spectroscopy, and sulfur and carbon concentrations by combustion-infrared absorption spectroscopy. In copper alloy additively fabricated structures, the concentrations of Cr, Zr, and other additive elements and impurity elements (excluding O, H, S, N, and C from impurities) can be obtained by appropriately combining X-ray fluorescence analysis, glow discharge mass spectrometry, and inductively coupled plasma mass spectrometry.

[0039] Furthermore, as mentioned above, the copper alloy additive manufactured body in this embodiment is composed of a Cu-Cr-Zr alloy, which is a precipitation-strengthened copper alloy, and can therefore be used as a conductive component. Therefore, in the copper alloy additive manufactured body of this embodiment, it is preferable that the conductivity is 40% IACS or higher. Furthermore, it is more preferable that the conductivity is 50% IACS or higher, and even more preferable that it is 60% IACS or higher. The upper limit of conductivity is not particularly limited, but it may be 93% IACS. The conductivity of a copper alloy additively fabricated structure can be obtained by measuring it using an overcurrent conductivity test.

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

[0041] (Powder preparation process S01) In this powder preparation step S01, copper alloy powder for metal AM consisting 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 having a Cr-containing compound is formed on the particle surface. In other words, in the copper alloy particles 50 of the copper alloy powder for metal AM according to this embodiment, it is preferable that the particle body 51 is made of a copper alloy containing Cr, and that a Cr compound layer 52 is formed on the outer surface of the particle body 51, as shown in Figure 2.

[0042] In this embodiment, the surface of the copper alloy particles constituting the copper alloy powder for metal AM used refers to the region from the outermost surface of the particle to a depth of 100 nm. Furthermore, it is preferable that the thickness of the Cr compound layer 52 on the particle surface of the copper alloy powder for metal AM is between 1 nm and 100 nm.

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

[0044] In the copper alloy powder used in this embodiment, cross-sectional observation reveals that Cr-containing compounds, which consist of compounds containing Cr, are dispersed at the grain boundaries inside the particle body 51. In this embodiment, it is preferable that, as a result of cross-sectional observation of the particles, the particle size of the Cr-containing compound observed at the grain boundaries inside the particle body 51 is within the range of 1 nm to 1000 nm.

[0045] In the copper alloy powder 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 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 size D50 measured by laser diffraction-scattering is in the range of 10 μm to 120 μm, the 10% cumulative particle size D10 is in the range of 1 μm to 80 μm, and the 90% cumulative particle size D90 is in the range of 10 μm to 150 μm.

[0047] The copper alloy powder used in this embodiment for metal atomization is produced by manufacturing a high-purity copper alloy ingot with few impurities using a continuous melting and casting apparatus, processing this copper alloy ingot into wire rods and cutting them to form a copper alloy raw material, and then atomizing this copper alloy raw material. In the copper alloy ingot produced by the continuous melting and casting apparatus, it is preferable that the O concentration is 10 masssppm or less, the H concentration is 5 masssppm or less, the S concentration is 15 masssppm or less, and the total content of impurity elements other than Cu (excluding O, H, and S) is 0.04 mass% or less. Furthermore, in the copper alloy raw materials described above, it is preferable that the O concentration is 10 masssppm or less, the H concentration is 5 masssppm or less, the S concentration is 15 masssppm or less, and the total content of impurity elements other than Cu and alloying elements (excluding O, H, and S) is 0.04 mass% or less.

[0048] Furthermore, in the copper alloy powder for metal AM used in this embodiment, it is preferable that the O concentration is 1000 masspm or less, the H concentration is 5 masspm or less, the S concentration is 10 masspm or less, and the N concentration is 10 masspm or less. In the copper alloy powder for metal AM, the total amount of additive elements other than alloying elements and impurity elements (excluding O, H, S, N, and C from impurities) may be 0.07 mass% or less, 0.06 mass% or less, 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. Furthermore, in copper alloy powder for metal AM, the upper limits of the content of additive elements other than alloying elements and impurity elements (excluding O, H, S, N, and C from impurities) are preferably 30 masssppm or less, more preferably 20 masssppm or less, and even more preferably 15 masssppm or less.

[0049] In this embodiment of copper alloy powder for metal AM, the alloying elements are Cr and Zr, and the impurities are components including impurity elements and O, H, S, N, and C. Furthermore, the copper alloy constituting this embodiment of copper alloy powder for metal AM may also contain additive elements and impurity elements other than the alloying elements (Cr and Zr). Examples of additive elements and impurity elements other than the alloying elements (Cr and Zr) constituting C18150 in copper alloy powder for metal AM 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.

[0050] In this embodiment, as described above, atomization is performed using molten alloy with a sufficiently reduced impurity content. This suppresses the consumption of alloying elements such as Cr and Zr through reaction with impurities, making it possible to generate Cr-containing compounds and Zr-containing compounds. By performing sufficient vacuuming and atmosphere control using gas during such atomization, it becomes possible to produce higher quality copper alloy powder for metal atomization.

[0051] (Modeling process S02) In this fabrication process S02, a copper alloy additive fabricated body is manufactured by sequentially repeating the following steps: a powder bed formation step S21 in which a powder bed containing the above-mentioned copper alloy powder for metal additive manufacturing is formed, and a fabrication bed formation step S22 in which the copper alloy powder for metal additive manufacturing at predetermined positions in the powder bed is solidified to form a fabrication bed.

[0052] In the molding bed formation process S22, a laser is used to solidify the copper alloy powder for metal additive manufacturing. By setting a high energy density for the laser, the degree of orientation of crystals having a plane orientation of {10¹}±15° in the stacking direction is increased. Therefore, in this embodiment, the laser energy density in the molding bed formation process S22 is set to 500 J / mm². 3 It is preferable to set it to the above, 600 J / mm 3 It is even more preferable to set the above. In addition, in this embodiment, the laser energy density in the molding bed formation process S22 is set to 700 J / mm². 3 It may be set to the above, or 750 J / mm 3 You may leave it at that.

[0053] (Heat treatment process S03) Next, heat treatment is performed as needed to properly precipitate materials, thereby improving conductivity and strength. Here, solution heat treatment and aging heat treatment may be performed as the heat treatment. Solution heat treatment is preferably carried out under the following conditions: heat treatment temperature: 900°C to 980°C, and holding time at the heat treatment temperature: 0.1 hours to 2 hours. The aging heat treatment is preferably carried out under the following conditions: heat treatment temperature: 400°C to 800°C, and holding time at the heat treatment temperature: 1 hour to 3 hours. Furthermore, if the solution treatment has progressed sufficiently in the molding process S02, the solution heat treatment may be omitted, and only the aging heat treatment may be performed directly. Furthermore, if the solution treatment process S02 has progressed sufficiently, the heat treatment process 03 may be omitted.

[0054] Through the various processes described above, the copper alloy additive body of this embodiment is manufactured.

[0055] According to this embodiment of the copper alloy additive fabricated body, which has the above configuration, the material is composed of a Cu-Cr-Zr alloy in which the Cr content is in the range of 0.5 mass% to 1.5 mass% and the Zr content is in the range of 0.02 mass% to 0.2 mass%. Therefore, it has excellent conductivity and strength and can be widely applied as a material for various parts.

[0056] Furthermore, in the copper alloy additive manufactured body of this embodiment, the body density is 99.1% or higher, resulting in fewer structural defects such as voids and superior quality. Furthermore, in the copper alloy additively fabricated body of this embodiment, the crystal orientation measurement by electron backscatter diffraction (EBSD) shows that the area ratio of crystals having a plane orientation of {10¹} ± 15° in a specific direction (the stacking direction in this embodiment) is 50% or more. Therefore, the crystal orientation is highly oriented, and the mechanical properties have sufficient anisotropy. Accordingly, the copper alloy additively fabricated body of this embodiment is particularly suitable as a copper alloy component for applications where anisotropy in mechanical properties is required.

[0057] Furthermore, in the copper alloy additively fabricated body of this embodiment, when the oxygen concentration is 300 mass sppm or less, oxygen-induced structural defects are even fewer, resulting in superior quality. Furthermore, in the copper alloy additive manufactured body according to this embodiment, when the sulfur concentration is 6 mas sppm or less, the number of sulfur-induced structural defects is even lower, resulting in superior quality. Furthermore, in the copper alloy additive manufactured body according to this embodiment, if the conductivity is 50% IACS or higher, this copper alloy additive manufactured body can be suitably used as a conductive member.

[0058] Although embodiments of the present invention, namely a copper alloy additive manufactured body and a method for manufacturing a copper alloy additive manufactured body, have been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the technical spirit of the invention. [Examples]

[0059] The results of the verification experiments conducted to confirm the effects of the present invention are described below.

[0060] (Test 1) High-purity copper raw materials of 4N grade were prepared, and a C18150 copper alloy ingot was produced using a continuous melting and casting apparatus. At this time, the O concentration was 10 masssppm or less, the H concentration was 5 masssppm or less, the S concentration was 15 masssppm 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 fabricated C18150 composition copper alloy ingot as a raw material, copper alloy powder for metal AM was prepared by gas atomization using argon gas. The powder was then classified to a particle size suitable for the powder bed of a laser PBF to obtain the copper alloy powder for metal AM of Example 1 of the present invention. The particle size distribution of the copper alloy powder for metal AM of Example 1 of the present invention was measured using a Microtrac MT3300EXII, and the result showed a particle size distribution of 10% cumulative particle diameter of 14 μm, 50% cumulative particle diameter of 31 μm, and 90% cumulative particle diameter of 52 μm. The component composition of this copper alloy powder for metal AM is shown in Table 1.

[0061] Using the above copper alloy powder for metal AM, a laminated body was fabricated by a commercially available laser PBF printer. The light source was a 400W Yb fiber laser, and the laser spot diameter was approximately 100μm. The energy density of the laser during shaping was 90 - 1541 J / mm 3 was set. In this way, the copper alloy laminated body of Invention Example 1 was obtained. The composition of the copper alloy laminated body of Invention Example 1 is shown in Table 1.

[0062] Also, 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 of Table 1. In the commercially available copper alloy powder for metal AM with a C18150 composition, the O concentration, H concentration, S concentration, and the content of impurity elements other than Cu (excluding O, H, and S) are high. Using this copper alloy powder, a laminated body was fabricated by a commercially available laser PBF printer. The light source was a 400W Yb fiber laser, and the laser spot diameter was approximately 100μm. The energy density of the laser during shaping was from 90 to 1541 J / mm 3 under the conditions. In this way, the copper alloy laminated body of Comparative Example 1 was obtained. The composition of the copper alloy laminated body of Comparative Example 1 is shown in Table 1.

[0063] Note that the O concentration in the copper alloy powder (copper alloy powder for metal AM) and the copper alloy laminated body shown in Table 1 was determined by the inert gas fusion - infrared absorption method, the H concentration and N concentration were determined by the inert gas fusion - thermal conductivity method, and the S concentration and C concentration were determined by the combustion - infrared absorption method. Also, except for copper, the concentrations of components other than these substances were determined by appropriately combining fluorescence X-ray analysis, glow discharge mass spectrometry, and inductively coupled plasma mass spectrometry.

[0064]

Table 1

[0065] As shown in Table 1, it has been confirmed that the copper alloy additive manufacturing structure and copper alloy powder for metal AM of Example 1 of the present invention have lower impurity content and lower O and S content compared to the copper alloy additive manufacturing structure 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 additively fabricated body had a C18150 composition, and the content of alloying elements (Cr, Zr) did not change significantly. On the other hand, regarding carbon (C), it has been confirmed that the carbon concentration of the copper alloy additive manufacturing structure is lower than that of the copper alloy powder used for metal additive manufacturing (AM). It is presumed that carbon (C) was removed during the process of melting the copper alloy powder for metal AM using laser PBF (Prescription Beam Fabrication).

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

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

[0068] Next, assuming that the allowable angle of deviation from the sample coordinate axis direction for each specified crystal plane of the copper crystal was set to 0 to 15 degrees, the area occupancy rate (crystal area ratio) of crystal grains having the orientation characteristics of the specified crystal plane that fall within this allowable angle range was determined in the measurement cross-section of the sample. Here, the area occupancy rate of the crystal grains was determined by accumulating the areas of crystal grains having the orientation characteristics of each specified crystal plane within the measurement area of ​​800 μm × 1200 μm in the cross-section of each sample. Since this area occupancy rate indicates the orientation characteristics of each specified crystal plane, in this invention, this area occupancy rate was used to calculate the degree of orientation in a certain specified crystal plane direction.

[0069] [Table 2]

[0070] In the copper alloy additive fabricated body of Example 1 of the present invention, it was confirmed that a high degree of orientation was observed in all directions: A1, A2, and A3. In particular, in the copper alloy additive fabricated body of Example 1 of the present invention, it was confirmed that the area ratio of crystals having a plane orientation of {10¹}±15° in the A3 direction was 50% or more, indicating a very high degree of orientation.

[0071] (Exam 2) Next, the copper alloy powder used in manufacturing the copper alloy additive manufacturing body of Example 1 of the present invention described above was prepared, and the energy density of the laser during manufacturing was changed to produce copper alloy additive manufacturing bodies of Examples 2 and 3 of the present invention and Comparative Examples 2 and 3. The copper alloy additive fabricated structures obtained from Examples 2 and 3 of the present invention and Comparative Examples 2 and 3 were evaluated for their crystal orientation characteristics (degree of crystal orientation) using the crystal grain area occupancy (crystal area ratio), similar to Example 1 of the present invention. The evaluation results are shown in Table 3. Note that Table 3 only shows {101} orientation in the A1 direction, {100} orientation in the A2 direction, and {101} orientation in the A3 direction.

[0072] Furthermore, the packing density of the copper alloy additively fabricated bodies of Examples 2 and 3 of the present invention and Comparative Examples 2 and 3 was evaluated as follows. The packing density in the evaluation cross-section of the copper alloy additively fabricated structure was evaluated from the area of ​​the evaluation cross-section of the copper alloy additively fabricated structure and the area occupied by voids observed in the evaluation cross-section of the copper alloy additively fabricated structure. In detail, after machining including mirror polishing was performed on the cross-section of the copper alloy additively manufactured object, the evaluation cross-section of the copper alloy additively manufactured object was observed using an optical microscope to identify void locations within the evaluation cross-section, the void-occupied area in the evaluation cross-section was calculated, and the density of the manufactured object was determined using equation (1). The evaluation results of the manufactured object density are shown in Table 3. Build density (%) = {(Area of ​​the evaluation cross-section of the copper alloy additively fabricated object - Area occupied by voids observed in the evaluation cross-section of the copper alloy additively fabricated object) / (Area of ​​the evaluation cross-section of the copper alloy additively fabricated object)} × 100 (1)

[0073] [Table 3]

[0074] As shown in Table 3, the laser energy density was set to 1027 J / mm². 3 The present invention, as exemplified by Example 2 and 770 J / mm 3 In Example 3 of the present invention, it was confirmed that a high degree of orientation was observed in all directions: A1, A2, and A3. In particular, in the copper alloy additive fabricated bodies of Examples 2 and 3 of the present invention, it was confirmed that the area ratio of crystals with a plane orientation of {10¹}±15° in the A3 direction was 97% or more, indicating a very high degree of orientation. Furthermore, the build density of the copper alloy additive manufactured bodies in Examples 2 and 3 of the present invention is higher than that of the copper alloy additive manufactured bodies in Comparative Examples 2 and 3, and is close to 100%, confirming that there are almost no structural defects such as voids and that the quality is excellent.

[0075] (Exam 3) Next, 770 J / mm 3The copper alloy additively fabricated body of Example 1 of the present invention, manufactured under the specified conditions, was subjected to heat treatment under the conditions shown in Table 4, and its electrical conductivity, 0.2% yield strength, and tensile strength were measured. Tensile test specimens were prepared with the longitudinal direction perpendicular to the layering direction, and the tensile strength was measured along the longitudinal direction of the specimen. The measurement results are shown in Table 4. The conductivity was measured at room temperature using an overcurrent conductivity test. The 0.2% proof stress and tensile strength were measured by performing a tensile test at room temperature according to the ASTM E8 / E8M-22 standard. Furthermore, 256 J / mm 3 From 1027 J / mm 3 The copper alloy additively fabricated body of Example 1 of the present invention, manufactured under the specified conditions, was subjected to heat treatment under the conditions shown in Table 5, and its Vickers hardness (in HV units) was measured at room temperature. The fabricated copper alloy additively fabricated body had a density exceeding 99.1%, indicating a sufficient density for evaluating Vickers hardness. The measurement results are shown in Table 5. Vickers hardness was measured in accordance with JIS Z 2244.

[0076] [Table 4]

[0077] [Table 5]

[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 copper alloy laminates with increased conductivity and excellent mechanical properties and conductivity. In addition, it was confirmed that by directly performing aging heat treatment without going through solution heat treatment after fabricating the copper alloy laminate, mechanical strength and conductivity can be improved. Furthermore, as shown in Table 5, it was confirmed that Vickers hardness can be adjusted by combining solution heat treatment and aging heat treatment, or by adjusting the heat treatment conditions of direct aging heat treatment.

[0079] From the above, it has been confirmed that the present invention makes it possible to provide a copper alloy additively fabricated body made of a Cu-Cr-Zr alloy, having few structural defects such as voids, and possessing high crystal orientation.

Claims

1. A copper alloy additively fabricated body made of a Cu-Cr-Zr alloy, 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 sulfur concentration is set at 6 mass ppm or less. The Cu-Cr-Zr alloy contains additive elements other than alloying elements and impurity elements in total amount to 0.04% by mass or less. The density of the molded object is said to be 99.1% or higher. A copper alloy additively manufactured body characterized in that, as a result of measuring the crystal orientation by electron backscatter diffraction in the sample cross-section of the copper alloy additively manufactured body, the area ratio of crystals having a plane orientation of {10¹} ± 15° in the powder stacking direction in the sample cross-section is 50% or more.

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

3. The copper alloy additive body according to Claim 1, characterized in that the additive elements and impurity elements other than the alloying elements are one or more selected from Mg, Ti, Ni, Si, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, P, Sb, Bi, Ag, and S.

4. The copper alloy additive fabricated body according to claim 1, characterized in that its conductivity is 50% IACS or higher.

5. The process of preparing copper alloy powder for metal AM, A powder bed forming step of forming a powder bed containing the aforementioned copper alloy powder for metal AM, A process of forming a molding bed by solidifying the copper alloy powder for metal AM at a predetermined position in the powder bed, A method for manufacturing a copper alloy additive body according to claim 1, comprising having the characteristics described above.

6. A method for manufacturing a copper alloy additive body according to claim 5, comprising an aging heat treatment step of maintaining the copper alloy additive body in a range of 400°C to 800°C.

7. A method for manufacturing a copper alloy additive body according to claim 5 or claim 6, comprising a solution heat treatment step of maintaining the copper alloy additive body in a range of 900°C to 980°C.

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