Copper alloy powder for additive manufacturing, its manufacturing method and evaluation method, copper alloy additive manufacturing method and copper alloy additive manufacturing method

Abstract

This invention provides a copper alloy powder for additive layer manufacturing with which a high strength, highly electrically conductive additive layer-manufactured copper alloy article is obtained. This invention is a copper alloy powder for additive layer manufacturing to be used for manufacturing an additive layer-manufactured object using an additive layer manufacturing process, the powder containing 0.70-1.5 weight% of chromium and 0.05-0.35 weight% of magnesium, the balance consisting of copper and unavoidable impurities. The present invention is also a method for evaluating a copper alloy powder for additive layer manufacturing, the method comprising: a step for carrying out additive layer manufacturing of an additive layer-manufactured copper alloy article using the copper alloy powder for additive layer manufacturing that is being evaluated; a step for measuring the electrical conductivity X (%IACS) and Vickers hardness Y (Hv) of the additive layer-manufactured copper alloy article; and a step for evaluating the copper alloy powder for additive layer manufacturing on the basis of whether or not the points (X, Y), when the electrical conductivity X (%IACS) and Vickers hardness Y (Hv) are plotted on a two-dimensional graph having an X-axis and a Y-axis, are located on the higher strength side and the higher electrical conductivity side of a boundary line given by (Y = -1.1X+300).

Description

[Technical Field]

[0001] The present invention relates to a copper alloy powder for additive manufacturing, a method for producing and evaluating the same, a method for producing a copper alloy additive manufacturing product, and a copper alloy additive manufacturing product. [Background technology]

[0002] In the above technical field, Patent Document 1 discloses a copper alloy powder for additive manufacturing that is produced by an atomization method and contains more than 1.00 mass % and not more than 2.80 mass % chromium, with the remainder being copper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6389557 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is generally a trade-off between the strength (hardness) and electrical conductivity of copper alloys, and the techniques described in the above documents have not yielded copper alloy additive manufacturing bodies that are both high in strength and high in electrical conductivity. An object of the present invention is to provide a technique for solving the above-mentioned problems. [Means for solving the problem]

[0005] In order to achieve the above object, the copper alloy powder according to the present invention comprises: By additive manufacturing Conductivity of 60% IACS or more and Vickers hardness of 230Hv or more Copper alloy additive manufacturing copper alloy powder for additive manufacturing used to manufacture an additive manufacturing object, It contains 0.70% by weight or more and 1.5% by weight or less of chromium, 0.05% by weight or more and 0.35% by weight or less of magnesium, and the balance is copper and unavoidable impurities. the law of nature, The apparent density of the powder measured according to the JIS Z 2504 method is 3.5 g / cm 3 That's all, The adhesive strength of the copper alloy powder obtained from the fracture envelope obtained by the shear test is 0.300 kPa or more and 0.400 kPa or less. Copper alloy powder for additive manufacturing.

[0006] In order to achieve the above object, a copper alloy additive manufacturing object according to the present invention is A copper alloy additive manufacturing object manufactured by additive manufacturing using the copper alloy powder for additive manufacturing with an additive manufacturing device, It contains 0.70% by weight or more and 1.5% by weight or less of chromium, 0.05% by weight or more and 0.35% by weight or less of magnesium, and the balance is copper and unavoidable impurities. And Conductivity of 60% IACS or more, Vickers hardness of 230Hv or more It is a copper alloy additive manufacturing body.

[0007] In order to achieve the above object, the manufacturing method according to the present invention comprises: an additive manufacturing process of additively manufacturing a copper alloy additive manufacturing body using the copper alloy powder for additive manufacturing by an additive manufacturing device; The copper alloy additive manufacturing body is heated to 400°C or more and 500°C or less. 0.5 hours or more and 10 hours or less an aging treatment step of holding the Including, Conductivity of 60% IACS or more and Vickers hardness of 230Hv or more This is a method for manufacturing a copper alloy additive manufacturing object. [Effects of the Invention]

[0010] According to the present invention, a copper alloy additive manufacturing product having high strength and high electrical conductivity can be obtained. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a graph showing the relationship between Vickers hardness and electrical conductivity of a layered object and the boundary line in Patent Document 1. [Figure 2] 1 is a flowchart showing the steps of a method for evaluating copper alloy powder for additive manufacturing in this embodiment. [Figure 3] 1A and 1B are a copper-magnesium binary alloy phase diagram and a chromium-magnesium binary alloy phase diagram for the copper alloy powder for additive manufacturing used in this embodiment. [Figure 4]1 is a graph showing the relationship between Vickers hardness and electrical conductivity of copper alloy additive manufacturing bodies obtained in the present example and the comparative example, and a boundary line. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the components described in the following embodiments are merely examples and are not intended to limit the technical scope of the present invention.

[0013] [First embodiment] In this embodiment, a new evaluation method for copper alloy powder for additive manufacturing will be described. Before that, the current state of copper alloy powder for additive manufacturing will be described.

[0014] <Current status of copper alloy powder for additive manufacturing> Additive manufacturing technology is capable of producing products with complex shapes that were difficult to achieve with conventional processing techniques, and is expected to be applied in a variety of fields. In particular, the application of metallic materials with excellent mechanical properties is desirable.

[0015] Among metallic materials, copper has excellent electrical and thermal conductivity, making it promising for use in additive manufacturing (AM) of products with complex shapes, such as heat sinks and heat exchangers. However, the materials that have been used as metal powders for AM to date have mainly been iron, nickel, aluminum, titanium, and their alloys, with few examples of copper and copper alloys being used. This is because copper has high electrical and thermal conductivity, meaning that the heat energy applied by a laser or other device during AM is rapidly dissipated and diffused, preventing it from being fully melted, making it difficult to obtain high-density AM objects.

[0016] In contrast, Patent Document 1 discloses a copper alloy powder for additive manufacturing (AM) containing more than 1.00% by mass but not more than 2.80% by mass of chromium, with the remainder being copper, produced by an atomization method. This copper alloy powder is rapidly solidified from a molten state during production, resulting in a supersaturated chromium solid solution. This reduces thermal diffusion and heat dissipation properties and thermal conductivity, making it easy to melt and mold even using a low-power molding device. During AM, the molded region is first melted and then rapidly solidified, resulting in a supersaturated chromium solid solution. Therefore, aging the AM body causes chromium to precipitate from the copper matrix, increasing the purity of the copper matrix, improving electrical conductivity, and simultaneously improving strength through precipitation strengthening.

[0017] According to the examples in Patent Document 1, aging treatment at 450°C or higher and 500°C or lower, at which the strength is maximized, results in a copper alloy additive manufacturing body having a hardness and conductivity of 47.64% IACS or higher and 73.96% IACS or lower, and a Vickers hardness of 213.3 Hv or higher and 259.8 Hv or lower.

[0018] <Evaluation method for copper alloy powder for additive manufacturing> However, there is generally a trade-off between the strength, hardness, and electrical conductivity of copper alloys, and for example, in the case of the additive manufacturing product described in Patent Document 1, the relationship between Vickers hardness and electrical conductivity after aging at 500°C to 700°C is summarized as shown in Figure 1. Figure 1 is a graph showing the relationship between Vickers hardness and electrical conductivity of the additive manufacturing product described in Patent Document 1, as well as the boundary line.

[0019] As shown in Figure 1, the relationship between Vickers hardness Y (Hv) and electrical conductivity X (%IACS) lies below the boundary line expressed by the following formula (1), i.e., in the region on the low strength and low electrical conductivity side. In general, including the case of Patent Document 1, electrical conductivity can be improved by increasing the aging temperature or lengthening the aging time, but overaging causes the precipitated chromium particles to coarsen, significantly reducing strength. This indicates that under the aging conditions that maximize strength, chromium is not completely precipitated from the copper matrix, and more chromium than the solid solubility limit remains in the matrix.

[0020] [Number 1] Y=-6X+680 (1)

[0021] It is desirable for practical copper alloys for additive manufacturing to not only achieve high density and exhibit the excellent electrical conductivity inherent to copper, but also to achieve both electrical conductivity and mechanical strength at a higher level. However, as described above, there is a trade-off between electrical conductivity and strength, and it is not easy to achieve both properties at the same time. For example, in Patent Document 1, a copper alloy for additive manufacturing that is in the upper region of the boundary line represented by the above formula (1), i.e., in the region on the high strength side and the high electrical conductivity side, has not been obtained.

[0022] In this embodiment, in order to achieve both high levels of electrical conductivity and mechanical strength within the aging temperature range of 400°C or higher and 500°C or lower, Equation (2) is used as a guideline for specifically expressing high strength and high electrical conductivity. By plotting the characteristics on a graph with electrical conductivity (%IACS) on the X-axis and Vickers hardness (Hv) on the Y-axis, the balance between strength and electrical conductivity can be evaluated as a linear function on an XY graph. There is a trade-off between strength and electrical conductivity, and as electrical conductivity increases, Vickers hardness decreases, so on an XY graph, this can be expressed as a linear function with a negative slope.

[0023] [Number 2] Y=-1.1X+300 (2)

[0024] It is known that electrical conductivity and thermal conductivity are roughly proportional to each other in metals, as is known from the Wiedemann-Franz law. Therefore, copper alloy additive manufacturing products manufactured by additive manufacturing using the copper alloy powder for additive manufacturing of the present invention with an additive manufacturing device have excellent electrical conductivity, and can therefore also be used as copper alloy additive manufacturing products with high thermal conductivity.

[0025] (Procedure for evaluation of copper alloy powder for additive manufacturing) FIG. 2 is a flowchart showing the procedure of the method for evaluating copper alloy powder for additive manufacturing in this embodiment.

[0026] In step S201 of Fig. 2, a powder layer for additive manufacturing is formed using the copper alloy powder for additive manufacturing to be evaluated. Then, in step S202, it is determined whether or not a powder layer suitable for additive manufacturing can be formed using the copper alloy powder for additive manufacturing to be evaluated. If the squeegeeability is poor and a powder layer suitable for additive manufacturing cannot be formed, in step S209, the copper alloy powder is evaluated as insufficient for additive manufacturing.

[0027] On the other hand, if the squeegeeability is sufficient and a powder layer suitable for additive manufacturing can be produced, in step S203, an additive manufacturing object is manufactured using the copper alloy powder for additive manufacturing to be evaluated using an additive manufacturing device or the like. In step S204, the electrical conductivity X (%IACS) and Vickers hardness Y (Hv) of the manufactured additive manufacturing object are measured. In step S205, it is determined whether the plot point (X, Y) on a two-dimensional graph (see Figure 4) with the measured electrical conductivity X (%IACS) and Vickers hardness Y (Hv) as axes is in the upper region (Y≧−1.1X+300) of the boundary line (Y=−1.1X+300).

[0028] If it is in the upper region (Y≧−1.1X+300), it is evaluated in step S207 as being sufficient as a copper alloy powder for additive manufacturing. On the other hand, if it is in the lower region (Y<−1.1X+300), it is evaluated in step S209 as being insufficient as a copper alloy powder for additive manufacturing.

[0029] According to the method for evaluating copper alloy powder for additive manufacturing of this embodiment, it is possible to evaluate copper alloy powder for additive manufacturing that can produce copper alloy additive manufacturing bodies with high strength and high conductivity.

[0030] [Second embodiment] In this embodiment, the characteristics of copper alloy powder for additive manufacturing that gave fully satisfactory results in the evaluation method for copper alloy powder for additive manufacturing of the first embodiment will be described.

[0031] <Highly rated materials> In this embodiment, we provide a method for manufacturing a raw material powder that can achieve characteristics in the region above the boundary line represented by the above formula (2), i.e., the region on the high strength side and high conductivity side, as well as the raw material powder and an additive manufacturing body obtained using the raw material powder.

[0032] The inventors aimed for the region above the boundary line expressed by the above formula (2), i.e., the region on the high strength and high conductivity side, and as a result, by adding magnesium to a copper-chromium alloy to create a ternary alloy, they discovered an alloy that has properties in the region above the boundary line expressed by the above formula (2), i.e., the region on the high strength and high conductivity side.

[0033] In other words, achieving a good balance between high electrical conductivity and high mechanical strength requires sufficient precipitation of chromium even at relatively low aging temperatures. Increasing the chemical potential of solute elements is effective in promoting their precipitation from the matrix (solvent element). Therefore, adding an element that increases the chemical potential of chromium in the matrix to a copper-chromium alloy enhances the repulsive interaction between the elements, raising the chemical potential of chromium and promoting precipitation. Therefore, we investigated adding an element that increases the chemical potential of chromium as a third element to a copper-chromium alloy. We searched for a candidate third element with a high repulsive interaction and found magnesium. Since magnesium has the potential to have a high repulsive interaction with both chromium and the matrix copper, as inferred from the phase diagram in Figure 3, even small amounts are likely to be effective in increasing the chemical potential of chromium. Furthermore, magnesium is one of the alloying elements with the least effect on increasing the resistivity of the matrix. Therefore, its addition as a third element to a copper-chromium alloy is expected to minimize its effect on electrical conductivity. In view of the above, the present inventors came up with the idea of ​​adding magnesium as a third element to a copper-chromium alloy, and after extensive investigations, they have completed the present invention.

[0034] Based on the above-mentioned considerations, in this embodiment, it has become possible to provide a copper alloy powder for additive manufacturing that can achieve both high electrical conductivity and high strength at a high level, and an additive manufactured body thereof.

[0035] More specifically, the copper alloy powder for additive manufacturing of this embodiment contains 0.70% by weight or more and 1.5% by weight or less of chromium, and 0.05% by weight or more and 0.35% by weight or less of magnesium, with the remainder being copper and unavoidable impurities.

[0036] Moreover, the copper alloy powder for additive manufacturing of this embodiment has a 50% particle size of 3.0 μm or more and 200 μm or less.

[0037] Furthermore, the copper alloy powder for additive manufacturing of this embodiment has an apparent density of 3.5 g / cm when measured by the measurement method of JIS Z 2504. 3 That's all.

[0038] Furthermore, the copper alloy powder for additive manufacturing of this embodiment has an adhesive strength of 0.600 kPa or less, as determined from a fracture envelope obtained by a shear test.

[0039] The copper alloy additive manufacturing body of this embodiment is produced by additive manufacturing using the copper alloy powder for additive manufacturing of this embodiment with an additive manufacturing device, and contains 0.70% by weight or more and 1.5% by weight or less of chromium and 0.05% by weight or more and 0.35% by weight or less of magnesium, with the remainder consisting of copper and unavoidable impurities.

[0040] The copper alloy additive manufacturing product of this embodiment has an electrical conductivity of 60% IACS or more.

[0041] The copper alloy additive manufacturing product of this embodiment has a Vickers hardness of 230 Hv or more.

[0042] The method for producing a copper alloy additive manufacturing object of this embodiment further includes an aging treatment step of holding the copper alloy additive manufacturing object of this embodiment at 400 to 500°C, more preferably 450 to 500°C.

[0043] The copper alloy powder for additive manufacturing of this embodiment is a copper-chromium alloy to which magnesium is added as a third element, making it possible to produce copper alloy additive manufacturing objects with excellent electrical conductivity and mechanical strength, which are located in the upper region of the boundary line represented by the above formula (2), i.e., the high-strength and high-conductivity region.

[0044] (Copper alloy powder for additive manufacturing according to this embodiment) The method for producing the copper alloy powder for additive manufacturing of this embodiment is not particularly limited, but a method in which powder particles are rapidly cooled and solidified from a molten state, such as gas atomization, water atomization, centrifugal atomization, plasma atomization, or plasma rotating electrode method, is preferred. From the viewpoint of mass production, gas atomization is particularly preferred. The produced powder can be classified under predetermined classification conditions using a known classification method to adjust the copper alloy powder for additive manufacturing to an appropriate particle size. An air classifier can be suitably used as a classification device for performing classification.

[0045] In copper-chromium alloys, which are precipitation-strengthened copper alloys, chromium supersaturated in the copper matrix precipitates during aging, improving the alloy's strength. To obtain copper alloy AM objects with high mechanical strength, a chromium content of 0.70 wt% or more is preferred. At less than 0.70 wt%, the amount of precipitation during aging is insufficient, resulting in insufficient strength improvement. The solubility limit of chromium in copper is said to be between 0.7 and 0.8 wt% at the eutectic temperature of approximately 1076°C. While this amount is small, using a powder production method such as atomization, which involves melting and rapidly solidifying metal, allows for the inclusion of chromium in the copper matrix at levels above the solubility limit. Furthermore, using powder bed fusion AM, which involves melting and rapid solidification using a laser or electron beam, allows for the production of AM objects with chromium in the copper matrix at levels above the solubility limit. However, if the chromium content exceeds 1.5 wt%, although the effect of further improving the mechanical strength is obtained, it will result in a significant decrease in electrical conductivity, so the chromium content is preferably 1.5 wt% or less.

[0046] As mentioned above, magnesium is an important element that is thought to increase the chemical potential of chromium, enhancing the repulsive interaction between elements and promoting chromium precipitation. If the magnesium content is less than 0.05 wt%, chromium precipitation will be insufficient, making it impossible to simultaneously achieve the high strength and high electrical conductivity of the present invention in a balanced manner. If the magnesium content exceeds 0.35 wt%, the magnesium ratio will increase, but increasing the magnesium content will not significantly improve the properties. Furthermore, excessive inclusion of expensive magnesium will increase costs. Therefore, the magnesium content is preferably 0.05 wt% to 0.35 wt%, and more preferably 0.06 wt% to 0.25 wt%.

[0047] In addition, the copper alloy powder for additive manufacturing of this embodiment may contain unavoidable impurities in addition to chromium and magnesium. The unavoidable impurities are those that are inevitably mixed in during the manufacturing process of the copper alloy powder for additive manufacturing, and examples thereof include oxygen, phosphorus, iron, aluminum, silicon, and titanium. These unavoidable impurities may reduce electrical conductivity, so the content of these unavoidable impurities is preferably 0.10 wt % or less, more preferably 0.05 wt % or less, and even more preferably 0.01 wt % or less.

[0048] Powders used in AM must be compatible with each step of the AM process, including the supply from a hopper to the build stage, the formation of a uniformly distributed powder layer with a certain thickness, and the melting and solidification process. To achieve this, the following conditions are required: particle size adjusted within an appropriate range, apparent density within an appropriate range, and powder flowability that allows supply from a supply hopper and the formation of an appropriate powder layer.

[0049] The 50% particle size of copper alloy powder for additive manufacturing (AM) refers to the 50% particle size (so-called median diameter, D50) of the powder in the volume-based cumulative particle size distribution measured by laser diffraction. It is preferably in the range of 3.0 μm to 200 μm. If the 50% particle size is less than 3.0 μm, the powder lacks fluidity, making it impossible to form a powder bed even in an AM laser-based powder bed fusion (PBF) AM device. Furthermore, the powder scatters violently, resulting in surface defects, such as redepositing on the AM object. If the 50% particle size is greater than 100 μm when AM laser-based PM fusion is used for AM, or greater than 200 μm when AM electron beam PM fusion is used for AM, the powder bed surface becomes rough, making it impossible to form a powder bed suitable for AM. Furthermore, the surface of the AM object becomes rough, resulting in poor appearance. The melt pool generated in the powder layer during beam irradiation does not reach the solidified layer directly below, resulting in insufficient melting and solidification, leading to defective molding. In laser powder bed fusion, the 50% particle size is preferably 3.0 μm to 100 μm, more preferably 5.0 μm to 75 μm, and even more preferably 10 μm to 45 μm. In electron beam powder bed fusion, the 50% particle size is preferably 10 μm to 200 μm, more preferably 25 μm to 150 μm, and even more preferably 45 μm to 105 μm.

[0050] The apparent density of copper alloy powder for additive manufacturing is 3.5 g / cm when measured using the JIS Z 2504 measurement method. 3 It is preferable that the apparent density is 3.5 g / cm or more. 3 If the squeegeeing time is less than this, the powder packing rate of the powder layer spread by squeegeeing will decrease, making it impossible to form an appropriate powder layer. Furthermore, the decrease in powder packing rate will cause voids to form in the layered object, reducing the density of the layered object.

[0051] In additive manufacturing, flowability is a particularly important powder characteristic. In powder bed fusion (PBF), in particular, it is the most important powder characteristic, directly linked to the quality of the additive manufactured object, as it determines the powder supply from the supply hopper, the powder supply from the recoater, and the formation of the powder layer on the build stage. In PBF, powder must be evenly spread to a consistent thickness on the build stage. This powder spreading process is called squeegeeing, and the quality of the powder's spreadability is referred to as squeegeeability. Powders used in AM require sufficient squeegeeability, which requires the powder to have appropriate flowability. The flow rate (FR) defined in JIS Z 2502 "Metal Powders - Flowability Measurement Method" is used as an index to measure the flowability of metal powders. However, with fine powders with a 50% particle size of 50 μm or less, which are primarily used for laser-based PBF, the powder does not flow out of the measurement container, making measurement impossible, and flowability cannot be evaluated. Therefore, as an index for evaluating the fluidity of fine powders, it is effective to use the adhesive strength of powders obtained by the single-plane shear test method for powders (hereinafter referred to as the shear test) specified in the Japan Powder Process Industry and Engineering Association standard (SAP15-13:2013) "Single-plane shear test method for powders." The adhesive strength can be determined from the fracture envelope of the powder layer obtained by measuring the shear stress generated when a powder layer formed by vertical compaction is subjected to vertical pressure and then slid horizontally. The shear test can be performed, for example, using a Freeman Technology FT4 powder rheometer. For copper alloy powders for additive manufacturing, if their adhesive strength is 0.600 kPa or less, they are judged to have sufficient fluidity to spread a uniform powder layer and have good squeegeeability. This allows for the production of high-density, homogeneous additive manufacturing objects. If the adhesive strength is greater than 0.600 kPa, the copper alloy powder for additive manufacturing has insufficient fluidity, resulting in poor squeegeeability and the inability to form an appropriate powder layer. Therefore, in copper alloy powder for additive manufacturing, it is desirable that the adhesive strength of the copper alloy powder obtained from the fracture envelope obtained by the shear test is 0.600 kPa or less.

[0052] (Copper alloy additive manufacturing body of this embodiment) Various known metal additive manufacturing techniques can be used to produce copper alloy AM objects. For example, in powder bed fusion, metal powder is spread evenly on a building stage using a blade or roller to form a powder layer, and then a laser or electron beam is irradiated at a predetermined position on the powder layer to sinter and melt the metal powder, repeating this process to produce an AM object. In the metal AM process, a large number of process parameters must be controlled to obtain high-quality AM objects. In laser-based powder bed fusion, there are many scanning conditions, such as laser output and laser scanning speed. Therefore, to set optimal scanning conditions, the main parameters are adjusted using energy density, an index that summarizes the main parameters. Energy density E [J / mm 3 ] is determined by E = P / (v × s × t), where P is the laser output, v is the laser scanning speed, s is the laser scanning pitch, and t is the powder layer thickness. In laser-based powder bed fusion, the energy density is 150 J / mm 3 More than 450J / mm 3 The energy density is preferably 150 J / mm or less. 3 If the energy density is less than 450 J / mm, the powder layer will not melt or will not fuse properly, resulting in defects such as voids in the additive manufacturing product. 3If the temperature exceeds this range, sputtering occurs, destabilizing the surface of the powder layer and resulting in defects such as voids in the additive manufacturing object. In electron beam powder bed fusion (EBFM), when the powder layer is irradiated with an electron beam, negative charges accumulate in the powder layer, causing the powder to rise into a mist, resulting in a "smoke" phenomenon and insufficient melting. Therefore, to prevent this charge-up, a preliminary step of preheating and pre-sintering the powder layer is required. However, if the preheating temperature is too high, sintering progresses, causing necking, making it difficult to remove the remaining powder from the additive manufacturing object after shaping. For this reason, the preheating temperature for copper alloy powder for AM is preferably set to 400°C or higher and 800°C or lower. While the metal AM technology using the powder bed fusion method has been exemplified here, general AM methods for producing additive manufacturing objects using the copper alloy powder for AM of the present invention are not limited to this method. For example, AM methods using directed energy deposition (DED) may also be used.

[0053] (Aging treatment) Aging the additively manufactured body causes the supersaturated chromium to precipitate, improving the body's strength and electrical conductivity. Therefore, the aging process is essential for achieving the high strength and high electrical conductivity characteristics of the present invention. The aging process can be performed by heating the additively manufactured body to a predetermined temperature and holding it for a predetermined period of time. The aging process is preferably performed in a reducing atmosphere, inert gas, or vacuum. The effectiveness of the aging process is determined by the combination of the aging temperature and the aging time, so it is important to set appropriate conditions that balance the desired properties and efficiency. The aging temperature is preferably between 400°C and 500°C, and more preferably between 450°C and 500°C. Aging at 450°C is preferred for particularly improved mechanical strength. For particularly high electrical conductivity, temperatures above 500°C are also possible. The aging time is preferably set to 0.5 hours or more and 10 hours or less when the aging temperature is less than 500°C, and preferably set to 0.5 hours or more and 3 hours or less when the aging temperature is 500°C or more. If the aging time is shorter than the set time, chromium precipitation will be insufficient. Furthermore, if the aging temperature exceeds the set time, over-aging will occur, causing the precipitated chromium to coarsen, resulting in a decrease in hardness. If the aging temperature is less than 400°C, it will take a long time to achieve the aging effect, which is not practical. Furthermore, if the aging temperature exceeds 500°C, over-aging will occur, causing the chromium precipitate phase to coarsen, resulting in a decrease in strength. In an additive manufacturing product produced using the copper alloy powder for additive manufacturing of the present invention, the repulsive interaction between chromium and magnesium makes it possible to sufficiently improve the electrical conductivity and mechanical strength even with an aging time of several hours at an aging temperature of 450°C.

[0054] (Evaluation of copper alloy additive manufacturing bodies) The Vickers hardness is measured by a method conforming to "JIS Z 2244: Vickers hardness test - Test method." The Vickers hardness can be measured, for example, by using a microhardness tester HMV-G21-DT manufactured by Shimadzu Corporation.

[0055] The additively manufactured body has a conductivity of 60% IACS or more. The conductivity can be measured, for example, by an eddy current conductivity meter. An example of an eddy current conductivity meter is the high-performance eddy current conductivity meter Sigma Check manufactured by Nihon Matec Co., Ltd. The IACS (International Annealed Copper Standard) is an internationally adopted standard for conductivity, based on the conductivity of annealed standard soft copper (volume resistivity: 1.7241 × 10 -2 The electrical conductivity is defined as 100% IACS (μΩm). The electrical conductivity can be adjusted by aging treatment, and it is preferable to adjust it appropriately depending on the desired Vickers hardness. The electrical conductivity is preferably 60% IACS or more.

[0056] According to this embodiment, it is possible to provide a copper alloy powder for additive manufacturing that can produce a copper alloy additive manufacturing body with high strength and high conductivity, and the copper alloy additive manufacturing body.

[0057] [Other embodiments] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the technical scope of the present invention. [Example]

[0058] The present invention will be specifically described below based on examples and comparative examples. The following examples and comparative examples are merely specific examples for facilitating understanding of the technical content of the present invention, and the technical scope of the present invention is not limited by these specific examples.

[0059] Copper alloy powders for additive manufacturing with the various compositions shown in Table 1 below were produced by gas atomization, and the resulting copper alloy powders were classified to have particle sizes of 10 μm or more and 45 μm or less for laser powder bed fusion and 45 μm or more and 105 μm or less for electron beam powder bed fusion.

[0060] The contents of the component elements in the obtained copper alloy powder for additive manufacturing were measured by ICP atomic emission spectroscopy. In addition, the apparent density (AD) (g / cm) of the obtained copper alloy powder for additive manufacturing was measured in accordance with JIS Z 2504. 3 ) was measured. In addition, the flow rate (FR) (sec / 50g) of the obtained copper alloy powder for additive manufacturing was measured in accordance with JIS Z 2502. In addition, the 50% particle size (D50) (μm) was measured by laser diffraction method (Microtrac MT3300: manufactured by Microtrac Bell Co., Ltd.).

[0061] A shear test was conducted using a powder rheometer FT4 (manufactured by Freeman Technology) to measure the adhesive force (kPa) of the obtained copper alloy powder for additive manufacturing. The squeegeeability of the obtained copper alloy powder for additive manufacturing was evaluated by actually spreading the powder to be used in the manufacturing test on the manufacturing stage of a 3D powder additive manufacturing machine (powder bed fusion method / laser method or electron beam method) to form a powder layer. Table 1 shows the measurement results of various powder properties for the copper alloy powders for additive manufacturing used in Examples 1 to 4 and Comparative Examples 1 to 10. Here, Comparative Example 8 is a copper fine powder for conductive materials produced using high-pressure water atomization, and Comparative Example 9 is a copper spherical powder produced using a plasma rotating electrode method. The copper alloy powders of Comparative Examples 8 to 10 had poor squeegeeability, making squeegeeing impossible and additive manufacturing unfeasible.

[0062] [Table 1]

[0063] Using the copper alloy powders for additive manufacturing in Examples 1 to 4 and Comparative Examples 1 to 7, additively manufactured objects to be tested were produced using a 3D powder additive manufacturing machine (SLM Solutions GmbH, SLM280HL) equipped with a Yb fiber laser with a wavelength of 1064 nm. The additive manufacturing was carried out under the following conditions: a layer thickness of 25 μm to 50 μm, a laser output of 300 W to 700 W, a scanning speed of 900 mm / sec to 1500 mm / sec, and an energy density of 150 J / mm 3 More than 450J / mm 3 The test was carried out under the following conditions:

[0064] Using the above-mentioned 3D powder additive manufacturing machine, cylindrical additive manufacturing objects with a diameter of 14 mm and a height of 10 mm were produced. The density of the produced additive manufacturing objects was measured by the Archimedes method using helium gas as the displacement medium (AccuPyc1330, manufactured by Shimadzu Corporation), and the relative density (%) was calculated with the theoretical density (density of an ingot material having the same composition as the additive manufacturing object) set at 100%. The measurement results are shown in Table 1. The additive manufacturing objects obtained using the copper alloy powders for additive manufacturing of Comparative Examples 8 to 10 were excluded from the following evaluation of the properties of the additive manufacturing objects.

[0065] The electrical conductivity (%IACS) of the additively manufactured bodies of Examples 1 to 4 and Comparative Examples 1 to 7, which were manufactured using a 3D powder additive manufacturing machine, was measured using an eddy current conductivity meter (high-performance eddy current conductivity meter Sigma Check, manufactured by Nihon Matec Co., Ltd.). The Vickers hardness (Hv) of each additively manufactured body was measured using a microhardness tester (microhardness tester HMV-G21-DT, manufactured by Shimadzu Corporation).

[0066] The produced additive manufacturing bodies were subjected to an aging treatment for one hour in an inert atmosphere at temperatures set to 400°C, 450°C, and 500°C. The conductivity of the aged additive manufacturing bodies was measured using an eddy current conductivity meter. The Vickers hardness was also measured using a microhardness tester. Table 2 shows the evaluation results of various properties of the additive manufacturing bodies of Examples 1 to 4 and Comparative Examples 1 to 7 produced using the 3D powder additive manufacturing machine.

[0067] [Table 2]

[0068] Figure 4, similar to Figure 1, was generated from the evaluation results of various properties in Table 2. Figure 4 is a graph showing the relationship between Vickers hardness and electrical conductivity of the copper alloy additive manufacturing bodies obtained in this example and the comparative example, as well as the boundary line. In Figure 4, Example 1-1 and Comparative Example 1-1 are plots of the measurement results of copper alloy additive manufacturing bodies that were subjected to aging treatment at 400°C using the copper alloy powder for additive manufacturing of Example 1 or Comparative Example 1. Furthermore, Example 1-2 and Comparative Example 1-2 are plots of the measurement results of copper alloy additive manufacturing bodies that were subjected to aging treatment at 450°C using the copper alloy powder for additive manufacturing of Example 1 or Comparative Example 1. Finally, Example 1-3 and Comparative Example 1-3 are plots of the measurement results of copper alloy additive manufacturing bodies that were subjected to aging treatment at 500°C using the copper alloy powder for additive manufacturing of Example 1 or Comparative Example 1. Below, copper alloy powders for additive manufacturing are evaluated based on whether or not a copper alloy additive manufacturing object with high strength (Vickers hardness of 230 Hv or more) and high conductivity (electrical conductivity of 60% IACS or more) can be obtained. Note that, depending on the application of the copper alloy additive manufacturing object, copper alloy additive manufacturing objects that do not have high strength and high conductivity may also be used.

[0069] (Evaluation of Examples and Comparative Examples) In Comparative Examples 1 and 2, the copper-chromium alloys did not contain magnesium, and therefore did not simultaneously achieve the high strength and high electrical conductivity required by the present invention. Furthermore, in Comparative Example 3, the magnesium content exceeded the magnesium content required by the present invention, and therefore did not simultaneously achieve the high strength and high electrical conductivity required by the present invention. Furthermore, in Comparative Example 4, the magnesium content was lower than the magnesium content required by the present invention, and therefore did not simultaneously achieve the high strength and high electrical conductivity required by the present invention.

[0070] Comparative Example 5 contains magnesium within the range of the present invention, but contains chromium exceeding the range of 2.00 wt %, which results in high Vickers hardness but low electrical conductivity, failing to simultaneously achieve the balanced high strength and high electrical conductivity of the present invention. Comparative Examples 6 and 7 contain magnesium within the range of the present invention, but do not contain a sufficient amount of chromium, which results in sufficient electrical conductivity but insufficient strength, failing to simultaneously achieve the balanced high strength and high electrical conductivity of the present invention.

[0071] In contrast to this, Examples 1 to 4 simultaneously achieve high strength and high conductivity in a well-balanced manner.

[0072] From the above, it was confirmed that this example can provide a copper alloy powder for additive manufacturing that can achieve excellent conductivity and strength, and a copper alloy additive manufacturing body that has excellent conductivity and strength.

Claims

1. A copper alloy powder for additive manufacturing used to manufacture a copper alloy additive manufacturing object having a conductivity of 60% IACS or more and a Vickers hardness of 230 Hv or more by an additive manufacturing method, The alloy contains 0.70% by weight or more and 1.5% by weight or less of chromium, 0.05% by weight or more and 0.35% by weight or less of magnesium, and the balance being copper and unavoidable impurities; The apparent density of the powder is 3.5 g / cm 3 or more as measured by the method of JIS Z 2504, A copper alloy powder for additive manufacturing, wherein the adhesive strength of the copper alloy powder obtained from a fracture envelope obtained by a shear test is 0.300 kPa or more and 0.400 kPa or less.

2. The copper alloy powder for additive manufacturing according to claim 1, containing 0.70 wt% or more and 1.5 wt% or less of chromium and 0.06 wt% or more and 0.25 wt% or less of magnesium, with the remainder consisting of copper and unavoidable impurities.

3. A copper alloy powder for additive manufacturing according to claim 1 or 2, having a median diameter D50 of 3.0 μm or more and 200 μm or less.

4. A copper alloy additive manufacturing object manufactured by additive manufacturing using the copper alloy powder for additive manufacturing according to any one of claims 1 to 3, with an additive manufacturing device, The alloy contains 0.70% by weight or more and 1.5% by weight or less of chromium, 0.05% by weight or more and 0.35% by weight or less of magnesium, and the balance being copper and unavoidable impurities; It has a conductivity of 60% IACS or more, A copper alloy additive manufacturing body having a Vickers hardness of 230 Hv or more.

5. an additive manufacturing process in which a copper alloy additive manufacturing body is additively manufactured by an additive manufacturing device using the copper alloy powder for additive manufacturing according to any one of claims 1 to 3; an aging treatment step of holding the copper alloy additive manufacturing body at 400°C or higher and 500°C or lower for 0.5 hours or higher and 10 hours or lower; Including, A method for manufacturing a copper alloy additive manufacturing body having a conductivity of 60% IACS or more and a Vickers hardness of 230 Hv or more.

Images