W-Pt-Cu alloy for bonding

Abstract

To provide a new technique which achieves a suitable joint between a tungsten member and a dissimilar metal member.SOLUTION: A manufacturing method moves platinum (Pt) in a Pt-W alloy containing the platinum (Pt) and tungsten (W) to a Cu source containing copper (Cu). The manufacturing method can manufacture an alloy material 10 in which a W phase 12 containing W as a main component, and a Pt-Cu phase 14 containing a Pt-Cu alloy as a main component are mixed. The alloy material 10 exhibits suitable joinability to a tungsten member because an interface between the W phase 12 and the Pt-Cu phase 14 is stable. The alloy material 10 contains the Pt-Cu phase 14, and accordingly also exhibits suitable joinability to a dissimilar metal member. Specifically, the alloy material is usable as a new joint material for achieving a suitable joint between the tungsten member and the dissimilar metal member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to alloy materials. For example, it relates to alloy materials that can be used as a joining material for joining tungsten members and metal members other than tungsten. [Background technology]

[0002] Tungsten components containing tungsten (W) (hereinafter also referred to as "W components") have a high melting point and a low coefficient of thermal expansion, resulting in excellent reliability in high-temperature environments. For this reason, W components are used in ultra-high-temperature parts exposed to high temperatures, such as divertors, accelerators, plasma discharge devices, high-temperature furnaces, and thin-film deposition equipment. On the other hand, tungsten is a rare and expensive metal, and is difficult to process, so it is often used in a state where it is joined with metal components other than tungsten (hereinafter also referred to as "dissimilar metal components"). For example, copper (Cu) is often used as the dissimilar metal component to be joined, from the standpoint of material cost and heat dissipation (thermal conductivity).

[0003] For joining W members and dissimilar metal members, brazing materials containing silver (Ag) or copper, for example, are used. Examples of such brazing materials are disclosed in Patent Documents 1 and 2. Specifically, Patent Document 1 discloses a technique for joining cemented carbide alloys, in which tungsten carbide (WC) is sintered using cobalt (Co), and a brazing material containing silver (Ag), copper (Cu), zinc (Zn), and cobalt (Co) is used. This suppresses the diffusion of Co from the cemented carbide alloy into the brazing material, preventing breakage due to a decrease in the strength of the cemented carbide alloy. On the other hand, Patent Document 2 describes the use of a brazing material containing phosphorus (P) when joining alumina-dispersed copper and a metal to be joined (for example, tungsten). The heat treatment temperature during joining is set to a range lower than the melting point of copper and higher than the melting point of copper that has been lowered by the eutectic reaction between phosphorus and copper. This joins the alumina-dispersed copper and the metal to be joined.

[0004] In addition, as a joining means other than brazing, the NDB method (Non Defective Bonding) can be mentioned. This NDB method is a technique for directly joining a W member and a dissimilar metal member, and an example thereof is disclosed in Non-Patent Documents 1 and 2. For example, in Non-Patent Document 1, the copper member is melted and cooled while the tungsten member and the copper member are in contact with each other. Non-Patent Document 1 predicts that by implementing such a joining means, the molten copper member enters the minute uneven surface of the W member, and a pseudo metal bond is formed due to an increase in the gravitational force between atoms.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0006]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, with the recent expansion of the uses of W members, a new technique that can more suitably join a W member and a dissimilar metal member has been demanded. The present invention has been made in response to such a demand, and its main object is to provide a new technique for realizing suitable joining between a tungsten member and a dissimilar metal member.

Means for Solving the Problems

[0008] The inventors conducted various experiments and studies to find a novel technique for joining tungsten members and dissimilar metal members, and as a result, discovered a novel alloy material that functions suitably as a joining material for W members. Specifically, they discovered that when an alloy containing Pt and W (Pt-W alloy) is heated in contact with a Cu source containing copper (Cu), the Pt in the Pt-W alloy surprisingly migrates to the Cu. Furthermore, this absorption of Pt by Cu proceeds as the Cu penetrates the grain boundaries of the Pt-W alloy, resulting in the formation of a ternary two-phase alloy material (hereinafter also referred to as "W-Pt-Cu alloy") in which a W phase, mainly composed of W, and a Pt-Cu phase containing Pt and Cu are mixed. Generally, it is thought that W and Cu do not mix with each other to form an alloy, and such an alloy has not been reported in the past. The inventors of this invention considered that this W-Pt-Cu alloy could be a novel bonding material that effectively joins dissimilar metal members, such as Cu, with W members, and analyzed the properties and formation mechanism of the alloy material. As a result, they found that the above W-Pt-Cu alloy is formed by the mechanism shown below.

[0009] First, as mentioned above, the Pt-W alloy, which is the precursor material for the W-Pt-Cu alloy, is an alloy containing Pt and W. Since the Pt-Cu alloy is more stable than the Pt-W alloy, it is thought that when the Pt-W alloy was brought into contact with the Cu source, the migration of Pt to Cu from the Pt-W alloy progressed. Furthermore, the interface between the W phase, which is mainly composed of W, and the Pt-Cu phase, which contains both Pt and Cu, is considered to be more stable than the interface between the Pt-W alloy and Cu. Now, looking at the bonding with the tungsten member, the stability of the interface between the W phase and the Pt-Cu phase leads to the stability of the bonding between the tungsten member and the alloy material. This is because, at the bonding surface, the tungsten member mainly bonds with the Pt-Cu phase. In this way, by preparing a Pt-W alloy as a precursor material and migrating Pt to Cu from the Pt-W alloy, it is possible to manufacture an alloy material in which W and Cu, which were previously thought not to form an alloy, are mixed. Furthermore, such alloy materials can serve as novel bonding materials that enable suitable joining of tungsten components and dissimilar metal components.

[0010] The manufacturing method disclosed herein is based on the above-mentioned findings and is a method for producing a ternary two-phase alloy material (W-Pt-Cu alloy) in which a W phase and a Pt-Cu phase are mixed. This manufacturing method is characterized by moving the platinum (Pt) of a Pt-W alloy containing platinum (Pt) and tungsten (W) to a Cu source containing copper (Cu). As described above, a W-Pt-Cu alloy can be produced by this manufacturing method. Such a W-Pt-Cu alloy exhibits suitable bonding properties with W members because the interface between the W phase and the Pt-Cu phase is stable, and also exhibits suitable bonding properties with dissimilar metal members (Cu members, Pt members, etc.) because it contains a Pt-Cu phase. In other words, according to the technology disclosed herein, suitable bonding between W members and dissimilar metal members can be achieved.

[0011] In one preferred embodiment of the manufacturing method disclosed herein, the Pt-W alloy is an intermetallic compound. An example of such an intermetallic compound Pt-W alloy is Pt2W. By using such Pt2W as a precursor, a W-Pt-Cu alloy in which the W phase and the Pt-Cu phase are finely mixed can be produced.

[0012] In one preferred embodiment of the manufacturing method disclosed herein, a Pt-W alloy is brought into contact with a Cu source. According to the inventors' research, direct contact between the Pt-W alloy and the Cu source causes the migration of platinum (Pt) from the Pt-W alloy to copper (Cu), thereby producing a W-Pt-Cu alloy.

[0013] Furthermore, in one preferred embodiment of the manufacturing method disclosed herein, it is preferable to heat the Pt-W alloy and the Cu source that are in contact with each other. This promotes the migration of platinum (Pt) from the Pt-W alloy to copper (Cu), thereby enabling the efficient production of a W-Pt-Cu alloy.

[0014] A preferred embodiment of the manufacturing method disclosed herein comprises a Pt-W alloy production step of producing a Pt-W alloy by heat treatment in contact with a Pt source containing platinum (Pt) and a W source containing tungsten (W), and a W-Pt-Cu alloy production step of producing a W-Pt-Cu alloy by heat treatment in contact with a Cu source, thereby transferring platinum (Pt) in the Pt-W alloy to Cu. As described above, a Pt-W alloy is required as a precursor material to produce a W-Pt-Cu alloy. Such a Pt-W alloy can be efficiently produced by heat treatment while the Pt source and the W source are in contact. Furthermore, according to the inventors' studies, even by simply bringing the Pt-W alloy into contact with the Cu source, the movement (diffusion) of Pt from the Pt-W alloy to Cu occurs, and a W-Pt-Cu alloy is produced. However, it takes a very long time to produce a sufficient W-Pt-Cu alloy by contacting only the Pt-W alloy and the Cu source. Therefore, in this embodiment, heat treatment is performed while the Pt-W alloy and the Cu source are in contact to promote the movement of Pt from the Pt-W alloy to Cu. As described above, the manufacturing method of this embodiment allows for the efficient production of a W-Pt-Cu alloy.

[0015] In the embodiment where the Pt-W alloy formation process is carried out, the heating temperature in the Pt-W alloy formation process is preferably 800°C to 1200°C. Furthermore, the heating time in the Pt-W alloy formation process is preferably 0.5 hours to 3 hours. By setting the conditions (heating temperature, heating time) of the Pt-W alloy formation process in this way, the Pt-W alloy can be efficiently produced, thereby improving the productivity of W-Pt-Cu alloy.

[0016] Furthermore, in the embodiment where the W-Pt-Cu alloy formation process is carried out, the heating temperature in the W-Pt-Cu alloy formation process is preferably 800°C or higher and 1200°C or lower. Also, the heating time in the W-Pt-Cu alloy formation process is preferably 0.5 hours or higher and 3 hours or lower. By setting the conditions (heating temperature, heating time) of the W-Pt-Cu alloy formation process in this way, the transfer of Pt from the Pt-W alloy to Cu can be appropriately generated, thereby improving the productivity of the W-Pt-Cu alloy.

[0017] In another preferred embodiment of the manufacturing method disclosed herein, a Pt-W alloy is formed at the boundary between the W source and the Pt source by interposing a platinum (Pt) source between a W source containing tungsten (W) and a Cu source, and a W-Pt-Cu alloy is formed by transferring the platinum (Pt) in the Pt-W alloy to Cu. In the above-described embodiment, a W-Pt-Cu alloy is produced by performing two or more heat treatments, including a Pt-W alloy production step and a W-Pt-Cu alloy production step. However, the manufacturing method disclosed herein is not limited to the above-described embodiment. For example, experiments have confirmed that a W-Pt-Cu alloy can be produced even when a Pt source is interposed between the W source and the Cu source and the heat treatment is performed together. Specifically, as in this embodiment, when the W source, Pt source, and Cu source are heated together, a Pt-W alloy is formed at the boundary between the W source and the Pt source. As the heat treatment progresses further, the Pt-W alloy and Cu (including the Pt-Cu alloy) become finely intermingled, and the Pt in the Pt-W alloy moves to Cu. As a result, a W-Pt-Cu alloy is formed between the W source and the Cu source, in which the W phase and the Pt-Cu phase are mixed.

[0018] In the configuration where the W source, Pt source, and Cu source are heated together, the heat treatment temperature is preferably between 800°C and 1200°C. Furthermore, the heat treatment time is preferably between 0.5 hours and 3 hours. By setting these heating conditions, the formation of the Pt-W alloy and the transfer of Pt from the Pt-W alloy to Cu can be appropriately facilitated, enabling the efficient production of the W-Pt-Cu alloy.

[0019] Furthermore, in an embodiment in which the W source, Pt source, and Cu source are heated together, during the heat treatment, 0.5 g / mm³ is added so as to sandwich the W source and the Cu source. 2 More than 5g / mm 2 It is preferable to pressurize the material at the following pressure. This allows the materials to adhere tightly to each other, thereby further improving the production efficiency of the W-Pt-Cu alloy.

[0020] Furthermore, in another embodiment of the manufacturing method disclosed herein, an intermediate metal member is interposed between the Pt-W alloy and the Cu source. In each of the embodiments described above, the Pt-W alloy and the Cu source are in direct contact, but the manufacturing method disclosed herein is not limited to such embodiments. According to experiments conducted by the inventors, even when another metal member (intermediate metal member) is interposed between the Pt-W alloy and the Cu source, the migration of platinum (Pt) from the Pt-W alloy to copper (Cu) occurs, and a W-Pt-Cu alloy is produced.

[0021] Furthermore, even in the embodiment in which the intermediate metal member described above is interposed, it is preferable to heat the Pt-W alloy in contact with the intermediate metal member and the Cu source. This promotes the movement of Pt from the Pt-W alloy to Cu, thereby improving the efficiency of W-Pt-Cu alloy formation.

[0022] Furthermore, in the embodiment in which the aforementioned intermediate metal member is interposed, it is preferable that the intermediate metal member contains at least Pt. This allows for more favorable migration of Pt from the Pt-W alloy to Cu, thereby further improving the efficiency of W-Pt-Cu alloy formation.

[0023] Next, alloy materials are provided as another aspect of the technology disclosed herein. The alloy materials disclosed herein are characterized by having a mixture of a W phase mainly composed of tungsten (W) and a Pt-Cu phase having platinum (Pt) and copper (Cu). Because the interface between the W phase and the Pt-Cu phase of this alloy material is stable, it can exhibit suitable bonding properties to W members. On the other hand, because this alloy material contains a Pt-Cu phase, it can also exhibit suitable bonding properties to dissimilar metal members (Cu members, Pt members, etc.). For this reason, the alloy material disclosed herein can be used as a bonding material for joining W members and dissimilar metal members. Furthermore, because this alloy material contains W, a high-melting-point metal, it is expected to exhibit superior heat resistance compared to conventional brazing materials. Moreover, since this alloy material is expected to have a coefficient of thermal expansion close to that of W members, it is also expected to suppress deterioration of the joint due to stress caused by differences in expansion and contraction.

[0024] Furthermore, in one preferred embodiment of the alloy material disclosed herein, a plurality of W phases are present in a matrix consisting of a Pt-Cu phase. By adopting a structure in which the W phase and Pt-Cu phase are mixed throughout the entire microstructure of the alloy material, more suitable bonding properties can be achieved for both tungsten members and dissimilar metal members.

[0025] Furthermore, in one preferred embodiment of the alloy material disclosed herein, SEM observation shows an area of ​​0.001 μm 2 ~1μm 2 (Preferably 0.001 μm) 2 ~0.1μm 2 The W phase of ) is present at 0.2 locations / μm 2 The alloy material has a W-phase-existing region with a density above the specified level, and this W-phase-existing region extends for 10 μm or more in a predetermined direction. Thus, an alloy material in which a W-phase-existing region with a density above the specified level extends for 10 μm or more can exhibit more suitable bonding properties to W members.

[0026] In one preferred embodiment of the alloy material disclosed herein, when the total number of metallic elements present in the W phase is 100 atm%, the number of tungsten atoms present in the W phase is 75 atm% or more. This makes it possible to obtain an alloy material that exhibits high bonding properties to tungsten members.

[0027] Furthermore, as another aspect of the technology disclosed herein, a joint is provided. Such a joint is characterized in that a first member containing tungsten and a second member are joined via the W-Pt-Cu alloy material. As described above, the W-Pt-Cu alloy material can be suitably used as a joining material for metal members containing tungsten (W members).

[0028] In one preferred embodiment of the joint disclosed herein, the first member is characterized by comprising at least one selected from the group consisting of tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, copper-tungsten composite material, and silver-tungsten composite material. The alloy material disclosed herein can exhibit suitable bonding properties to the first member made of the W-type material described above.

[0029] In one preferred embodiment of the joint disclosed herein, the second member is characterized by comprising at least one selected from the group consisting of copper, platinum, platinum-copper alloy, platinum-tungsten alloy, and copper alloy. The alloy material disclosed herein can exhibit particularly suitable bonding properties for dissimilar metal members comprising at least one of Cu, Pt, and W as described above. Furthermore, the second member of the joint disclosed herein is not limited to dissimilar metal members as described above, but may be the same tungsten member as the first member. That is, the W-Pt-Cu alloy material disclosed herein can be used not only for bonding tungsten members to dissimilar metal members, but also for bonding tungsten members to each other. [Brief explanation of the drawing]

[0030] [Figure 1] This is a schematic cross-sectional view showing an alloy material according to one embodiment. [Figure 2] This is a schematic cross-sectional view showing a joint according to one embodiment. [Figure 3] This is a cross-sectional SEM image of sample A-1 used for analysis. [Figure 4] (a) is the elemental map of W based on EDX analysis of sample A-1 for analysis, and (b) is the elemental map of Pt. [Figure 5](a) is the EDX spectrum in region α in Figure 3(b), and (b) is the EDX spectrum in region β. [Figure 6] This graph shows the concentration distributions of W and Pt along the line segment X in Figure 3(b). [Figure 7] (a) is an image showing the electron diffraction results in region α in Figure 3(b), and (b) is an image showing the electron diffraction results in region β. [Figure 8] (a) and (b) are images of the crystal structure of the sample A-1 analyzed using EBSD, and (c) is an image of (b) with the tungsten and Pt2W separated and colored. [Figure 9] (a) shows the grain size distribution in the W plate of the sample A-1 used for analysis, and (b) shows the grain size distribution in the Pt-W alloy. [Figure 10] (a) and (b) are cross-sectional SEM images of sample A-2 used for analysis. [Figure 11] (a) is an image of the crystal structure of sample A-2 analyzed using EBSD, and (b) is an image of (a) separated into the W phase and the Pt-Cu phase and colored. (c) is an image showing the crystal orientation of the crystal grains of the Pt-Cu phase in (b), and (d) is an image showing the crystal orientation of the crystal grains of the W phase in (b). [Figure 12] (a) shows the particle size distribution in the Pt-Cu phase of the sample A-2 used for analysis, and (b) shows the particle size distribution in the W phase. [Figure 13] (a) is a cross-sectional SEM image (250x magnification) of sample 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 14] (a) is a cross-sectional SEM image (1000x magnification) of sample 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 15] (a) is a cross-sectional SEM image (10,000x magnification) of sample 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 16](a) is a cross-sectional SEM image (50,000x magnification) of sample 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 17] This is an SEM image showing the area where elemental analysis was performed on Sample 1. [Figure 18] These are SEM images of Sample 1, where (a) shows the boundary between the Cu member and the W member, and (b) and (c) are magnified images of the boundary area. [Figure 19] This figure shows the results of the HAADF-STEM image and elemental mapping image of Sample 1. [Figure 20] Figure 19 shows the EDX spectrum of the W-Pt-Cu alloy. [Figure 21] This is the W-phase EDX spectrum from the HAADF-STEM image of Sample 1. [Figure 22] This is the EDX spectrum of the Pt-Cu phase in the HAADF-STEM image of Sample 1. [Figure 23] (a) is a cross-sectional SEM image (5000x magnification) of sample 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 24] (a) is a cross-sectional SEM image (50,000x magnification) of sample 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 25] This graph shows the concentration distributions of W, Pt, and Cu along line segment X1 in Figure 23(b). Note that (a) in the figure shows the analysis results for Pt, (b) shows the analysis results for W, and (c) shows the analysis results for Cu. [Figure 26] (a) is a cross-sectional SEM image (5000x magnification) of sample 3, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 27] (a) is a cross-sectional SEM image (50,000x magnification) of sample 3, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 28](a) is a cross-sectional SEM image (200,000x magnification) of sample 3, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 29] (a) is a cross-sectional SEM image (5000x magnification) of sample 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 30] (a) is a cross-sectional SEM image (50,000x magnification) of the Pt-Cu layer of sample 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 31] (a) is a cross-sectional SEM image (50,000x magnification) of the Pt-W layer of sample 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 32] (a) is a cross-sectional SEM image (50,000x magnification) of the W-Pt-Cu layer of sample 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 33] (a) is a cross-sectional SEM image (50,000x magnification) of the tungsten component of sample 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 34] This graph shows the concentration distributions of W, Pt, and Cu along line segment X2 in Figure 29(a). In the figure, (a) shows the analysis results for Pt, (b) shows the analysis results for W, and (c) shows the analysis results for Cu. [Figure 35] (a) is a backscattered electron image of sample 4 (5000x magnification), (b) is a magnified view of region α in (a) (20000x magnification), and (c) is a magnified view of region β in (a) (20000x magnification). [Figure 36] (a) is a cross-sectional SEM image (20,000x magnification) of region α of sample 4, and (b) to (d) are elemental maps of Cu, Pt, and W based on EDX analysis, respectively. [Figure 37] (a) is a cross-sectional SEM image (20,000x magnification) of region β of sample 4, and (b) to (d) are elemental maps of Cu, Pt, and W based on EDX analysis, respectively. [Figure 38] This figure shows the results of the HAADF-STEM image and elemental mapping image of sample 4. [Figure 39] This graph shows the concentration distributions of Pt, Cu, and W along line segment X3 in Figure 38. [Figure 40] This figure shows the results of HAADF-STEM images and elemental mapping images at the interface between the W plate of Sample 4, the W phase of the W-Pt-Cu layer, and the Pt-Cu phase of the W-Pt-Cu layer. [Figure 41] This graph shows the concentration distributions of Pt, Cu, and W along line segment X4 in Figure 40. [Figure 42] This graph shows the concentration distribution of O and Fe along line segment X4 in Figure 40. [Figure 43] (a) is an image showing the electron diffraction results in region α in Figure 38(a), (b) is an image showing the electron diffraction results in region β, (c) is an image showing the electron diffraction results in region γ, and (d) is an image showing the electron diffraction results in region δ. [Figure 44] This figure shows the results of HAADF-STEM images and elemental mapping images on the W plate of sample 4. [Figure 45] This figure shows the results of HAADF-STEM images and elemental mapping images of the Pt-W layer in sample 4. [Figure 46] This figure shows the results of HAADF-STEM images and elemental mapping images of the Pt-Cu layer in Sample 4. [Figure 47] Figure 44 shows the EDX spectrum in the Pt-Cu region. [Figure 48] Figure 40 shows the EDX spectrum in the Pt-Cu region. [Figure 49] Figure 45 shows the EDX spectrum in the Pt-Cu region. [Figure 50] Figure 46 shows the EDX spectrum in the Pt-Cu region. [Figure 51](a) is a cross-sectional SEM image (5000x magnification) of sample 5, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 52] (a) is a cross-sectional SEM image (50,000x magnification) of sample 5, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 53] (a) is a cross-sectional SEM image (5000x magnification) of sample 6, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 54] (a) is a cross-sectional SEM image (50,000x magnification) of sample 6, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 55] (a) is a cross-sectional SEM image (5000x magnification) of sample 7, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 56] (a) is a cross-sectional SEM image (50,000x magnification) of the Pt-W layer of sample 7, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 57] (a) is a cross-sectional SEM image (50,000x magnification) of the W-Pt-Cu layer of sample 7, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 58] (a) is a cross-sectional SEM image (50,000x magnification) of the W plate of sample 7, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 59] (a) is a cross-sectional SEM image (50,000x magnification) of the interface between the W plate and the W-Pt-Cu layer of sample 7, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 60] (a) is a cross-sectional SEM image (5000x magnification) of the uncoated area of ​​sample 8, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 61](a) is a cross-sectional SEM image (50,000x magnification) of the uncoated area of ​​sample 8, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 62] (a) is a cross-sectional SEM image (5000x magnification) of the Cu-coated area of ​​sample 8, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 63] (a) is a cross-sectional SEM image (50,000x magnification) of the W-Pt-Cu layer formed on the Cu coated portion of sample 8, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 64] (a) is a cross-sectional SEM image (50,000x magnification) of the W-Pt-Cu layer formed on the Cu coated portion of sample 8, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 65] (a) is a cross-sectional SEM image (50,000x magnification) of the boundary between the W-Pt-Cu layer formed on the Cu coated portion of sample 8 and the W plate, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 66] (a) is a cross-sectional SEM image (250x magnification) of sample 9, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. [Figure 67] (a) is a cross-sectional SEM image (1000x magnification) of sample 9, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. [Figure 68] (a) is a cross-sectional SEM image (5000x magnification) of sample 9, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. [Figure 69] (a) is a cross-sectional SEM image (50,000x magnification) of sample 9, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. [Figure 70] (a) is a cross-sectional SEM image (5000x magnification) of sample 10, (c) is an elemental map of W based on EDX analysis, and (d) is an elemental map of Pt. [Figure 71] This is a cross-sectional SEM image (5000x magnification) of sample 11. [Figure 72] This is a cross-sectional SEM image (50,000x magnification) of sample 11. [Figure 73] (a) is a cross-sectional SEM image (5000x magnification) of sample 12, and (b) to (e) are elemental maps of W, Cu, Pt, and Au based on EDX analysis, respectively. [Figure 74] (a) is a cross-sectional SEM image (50,000x magnification) of sample 12, and (b) to (e) are elemental maps of W, Cu, Pt, and Au based on EDX analysis, respectively. [Modes for carrying out the invention]

[0031] An embodiment of the technology disclosed herein will be described below. Matters other than those specifically mentioned herein but necessary for implementing the technology disclosed herein can be understood as design matters for those skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed herein and common technical knowledge in the relevant field. In this specification, "A~B (A, B are numerical values)" means "A or greater and B or less".

[0032] 1.Alloy material Figure 1 is a schematic cross-sectional view of the alloy material according to this embodiment. As shown in Figure 1, the alloy material (W-Pt-Cu alloy) 10 according to this embodiment is a ternary two-phase alloy material in which the W phase 12 and the Pt-Cu phase 14 are mixed (see Figure 1). The individual phases included in the alloy material 10 according to this embodiment will be described below.

[0033] (1)W phase The W phase 12 is a phase mainly composed of tungsten. In this specification, "mainly composed of tungsten" means that elements other than tungsten are intentionally not included. Therefore, a phase that contains unavoidable impurities (metal elements other than W) derived from raw materials or manufacturing processes as minor components is included in the concept of "W phase" in this specification. For example, if the total number of metal elements in one phase of a two-phase alloy is 100 atm%, and the number of W atoms in that one phase is 75 atm% or more, then it can be said that "a W phase mainly composed of tungsten has been formed." Furthermore, from the viewpoint of improving the bonding properties between the alloy material 10 and the W member according to this embodiment, the number of W atoms in the W phase is preferably 77.5 atm% or more, more preferably 80 atm% or more, and particularly preferably 82.5 atm% or more. The upper limit of the number of W atoms in the W phase is not particularly limited and may be 99.5 atm% or less, 97.5 atm% or less, 95 atm% or less, 92.5 atm% or less, or 90 atm% or less. In this specification, "number of atoms" is a numerical value based on elemental analysis obtained by performing energy dispersive X-ray spectroscopy (EDX) on cross-sectional SEM images of the alloy material.

[0034] In addition, unavoidable impurities that may be present in phase W 12 include copper (Cu), platinum (Pt), molybdenum (Mo), iron (Fe), cobalt (Co), nickel (Ni), gold (Au), and thorium (Th). Furthermore, tungsten in phase W 12 may exist in its elemental form, as a compound (oxide, etc.), or as an alloy with other metallic elements.

[0035] (2) Pt-Cu phase The Pt-Cu phase 14 is a phase containing platinum (Pt) and copper (Cu). Such a Pt-Cu phase 14 only needs to contain Pt and Cu; there is no intention to exclude the inclusion of a third metallic element other than Pt and Cu. Furthermore, the Pt-Cu phase 14 does not need to have Pt and Cu as its main components; the aforementioned third metallic element may be the main component. As will be described in detail later, depending on the materials and manufacturing methods used to produce the alloy material 10, a third metallic element other than Pt and Cu can also be the main component of the Pt-Cu phase 14. Specifically, when the total number of metal atoms in the Pt-Cu phase is set to 100 atm%, the total number of Pt and Cu atoms may be 20 atm% or more, 30 atm% or more, or 40 atm% or more. Furthermore, considering the bonding properties with copper components, the total number of Pt and Cu atoms is preferably 50 atm% or more, more preferably 65 atm% or more, even more preferably 75 atm% or more, and particularly preferably 85 atm% or more. On the other hand, the upper limit of the total number of Pt and Cu atoms in the Pt-Cu phase is not particularly limited and may be 99.5 atm% or less, 99 atm% or less, 97.5 atm% or less, or 95 atm% or less. The third metallic element that may be included in the Pt-Cu phase 14 is W, Mo, Fe, Pd, Ir, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, Th, etc. Among these third metallic elements, those that form alloys more readily with Cu than with W (e.g., Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, Th, etc.) can become the main components of the Pt-Cu phase 14.

[0036] Furthermore, there are no particular limitations on the number of Pt and Cu atoms present in the Pt-Cu phase. For example, the number of Pt atoms in the Pt-Cu phase may be 0.1 atm% or more, 0.5 atm% or more, or 1 atm% or more. On the other hand, the upper limit of the number of Pt atoms may be 25 atm% or less, 22.5 atm% or less, 20 atm% or less, or 17.5 atm% or less. Also, the number of Cu atoms in the Pt-Cu phase may be 15 atm% or more, 20 atm% or more, 30 atm% or more, or 40 atm% or more. Considering the bonding properties with copper members, the number of Cu atoms is preferably 50 atm% or more, more preferably 65 atm% or more, even more preferably 75 atm% or more, and particularly preferably 80 atm% or more. On the other hand, the upper limit of the number of Cu atoms may be 85 atm% or less, 82.5 atm% or less, or 80 atm% or less. As mentioned above, the number of Pt and Cu atoms present in the Pt-Cu phase is not particularly limited. For example, by bringing the alloy material 10 into contact with a Cu component, Pt can be diffused into the Cu component, thereby reducing the number of Pt atoms in the alloy material 10. Similarly, by bringing a component capable of diffusing Cu (e.g., Au, Ni) into contact with the alloy material 10, the number of Cu atoms in the alloy material 10 can be reduced.

[0037] (3) Microstructure of alloy materials Next, the structure of the alloy material 10 according to this embodiment will be described. As shown in FIG. 1, the alloy material 10 according to this embodiment is a ternary two-phase alloy in which the above-described W phase 12 and Pt-Cu phase 14 are mixed. That is, in the alloy material 10 according to this embodiment, the W phase 12 and the Pt-Cu phase 14 are present in a mixed state throughout the metal structure. Typically, in this alloy material 10, a matrix composed of the Pt-Cu phase 14 is formed, and a plurality of W phases 12 are present in the matrix of the Pt-Cu phase 14. Thus, in the alloy material 10 according to this embodiment, since the interface between the W phase 12 and the Pt-Cu phase 14 is stable, high bonding properties can be exhibited with respect to the W member, while having the Pt-Cu phase 14, suitable bonding properties can be exhibited with respect to dissimilar metal members (such as Cu members and Pt members). As an example of the alloy material (W-Pt-Cu alloy) disclosed herein, a form in which a plurality of long island-shaped W phases are scattered so as to extend in the thickness direction, and a Pt-Cu phase is formed so as to fill between the plurality of W phases can be cited (see, for example, FIGS. 16(a) and 19). However, the shape of the W phase is not limited to the above-described long island shape, and may be substantially spherical (see, for example, FIG. 52(a)).

[0038] Note that the alloy material disclosed herein is not limited to a form in which a plurality of W phases are scattered throughout the alloy material. For example, in a specific region of the Pt-Cu phase, W phases may be present at a density of a certain level or more (see FIG. 73(a)). In this specification, the region where W phases are present at a density of a certain level or more is referred to as a "W phase present region". More specifically, the "W phase present region" in this specification means that in SEM observation, the area of the W phase is 0.001 μm 2 ~1 μm 2 (preferably 0.001 μm 2 ~0.1 μm 2 ) and the W phase is present at 0.2 locations / μm in the Pt-Cu phase in the range of 1 μm 2 2This is a region where the W phase exists at the above density. Furthermore, the presence of such a W phase region for 10 μm or more in a predetermined direction allows for suitable bonding properties to both the W member and the dissimilar metal member. Note that the "direction in which the W phase region exists" is not particularly limited. That is, if a W phase region where the W phase is densely concentrated exists for 10 μm or more in at least one direction (for example, the thickness direction, width direction, or depth direction), an alloy material exhibiting suitable bonding properties to both the tungsten member and the dissimilar metal member can be obtained. As mentioned above, the density of the W phase in the W phase region is 0.2 locations / μm 2 This is appropriate. However, considering the bonding properties with the W member, the density of the W phase in the W phase-present region should be 0.3 locations / μm 2 The above is more appropriate, 0.5 locations / μm 2 The above is even more appropriate. Furthermore, from the viewpoint of further improving the bonding properties with the W member, the density of the W phase in the W phase-present region should be 0.5 locations / μm 2 The above is preferable, at 1 location / μm 2 The above is more preferable, at 1.5 locations / μm 2 The above is even more preferable, at 2 locations / μm 2 The above is particularly preferable. On the other hand, considering the bonding properties with dissimilar metal members (such as Cu members), the density of the W phase in the W phase-present region is 100 locations / μm 2 The following is appropriate, with 50 locations / μm 2 The following is preferable, 10 locations / μm 2 The following is more preferable: 7.5 locations / μm 2 The following is even more preferable: 5 locations / μm 2 The following are particularly preferred, for example, 4 locations / μm 2 It could be the following:

[0039] Furthermore, the average area of ​​each W phase is 1 μm². 2 The following is preferred: 0.75 μm 2 The following is more preferable: 0.5 μm 2 The following is more preferable: 0.25 μm 2The following is particularly preferable. The presence of such minute W phases in the Pt-Cu phase matrix allows for more favorable bonding properties to both tungsten members and dissimilar metal members. Furthermore, the lower limit of the average area of ​​the W phase is not particularly limited, but is 0.001 μm. 2 It may be greater than or equal to 0.005 μm 2 It may be greater than or equal to 0.01 μm 2 It may be greater than or equal to 0.05 μm 2 The above is also acceptable. The "average area of ​​the W phase" can be obtained by extracting 50 or more (preferably 85) W phases confirmed by SEM observation and calculating the average value of the areas of the extracted W phases.

[0040] Furthermore, it is preferable that the crystal grains constituting the W phase are fine. For example, the D of the crystal grains constituting the W phase 50 The particle size is preferably 1000 nm or less, more preferably 900 nm or less, even more preferably 800 nm or less, and particularly preferably 700 nm or less. On the other hand, the D of the crystal grains of the W phase 50 The lower limit of the particle size is not particularly limited and may be 100 nm or larger, 200 nm or larger, 300 nm or larger, or 400 nm or larger. On the other hand, it is preferable that the crystal grains constituting the Pt-Cu phase are fine. For example, the D of the crystal grains constituting the Pt-Cu phase 50 The particle size is preferably 800 nm or less, more preferably 600 nm or less, even more preferably 400 nm or less, and particularly preferably 200 nm or less. On the other hand, the D of the crystal grains of the Pt-Cu phase 50The lower limit of the particle size is not particularly limited and may be 20 nm or larger, 40 nm or larger, 60 nm or larger, or 80 nm or larger. Because the W phase and the Pt-Cu phase are each composed of such fine crystal grains, the W phase and the Pt-Cu phase can be suitably mixed, thereby improving the bonding ability between the W member and the dissimilar metal member. When comparing the relative sizes of the crystal grains of the W phase and the Pt-Cu phase, it is preferable that the W phase is composed of relatively large crystal grains and the Pt-Cu phase is composed of relatively minute crystal grains. Note that "D of crystal grains" in this specification 50 "Particle size" refers to the cumulative 50% from the fine particle side in the particle size distribution of crystal grains based on the number of grains. Furthermore, "crystal grain particle size" is the "equivalent circular diameter of the crystal grain" obtained by performing crystal analysis using electron backscatter diffraction (EBSD) on SEM images of alloy materials.

[0041] 2.Zygote Next, a joint formed by joining two types of members using the alloy material 10 described above will be explained. Figure 2 is a schematic cross-sectional view showing the joint according to this embodiment. In such a joint 100, a first member (W member) 20 containing tungsten and a second member 30 are joined via the alloy material 10 described above. As described above, in the alloy material 10 according to this embodiment, the interface between the W phase and the Pt-Cu phase is stable, so it can exhibit suitable bonding properties to the W member 20. On the other hand, since the Pt-Cu phase 14 is present throughout the entire structure of the alloy material 10, it can also bond suitably to dissimilar metal members that are suitably bonded to Pt-Cu alloys. For this reason, the alloy material 10 disclosed herein functions as a bonding material for joining the first member (W member) 20 and the second member 30.

[0042] Furthermore, because this alloy material 10 contains W, a high-melting-point metal, it exhibits superior heat resistance compared to conventional brazing materials. Moreover, because this alloy material 10 has a coefficient of thermal expansion close to that of the W member 20, it can suppress damage to the joint (alloy material 10) caused by large stresses resulting from differences in expansion and contraction. Therefore, the joint 100 joined with this alloy material 10 is particularly expected to be used in ultra-high temperature components such as divertors, accelerators, plasma discharge devices, high-temperature furnaces, and thin-film forming devices.

[0043] The first member (W member) 20 is not particularly limited as long as it is a solid metal member containing W. Examples of materials for such W member 20 include tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, copper-tungsten alloy, and silver-tungsten alloy. Furthermore, the first member (i.e., the W member) in this specification is not limited to a member consisting solely of the above-mentioned tungsten material, but may be a composite material formed by combining tungsten material with other materials. Examples of materials that can be combined with tungsten material include various metallic materials such as copper (Cu), platinum (Pt), molybdenum (Mo), iron (Fe), cobalt (Co), nickel (Ni), gold (Au), and thorium (Th), as well as high-melting-point ceramics such as tria (ThO2) and yttria. For the sake of explanation, Figure 2 shows a plate-shaped W member 20, but the shape of the W member is not particularly limited. For example, the shape of the W member can be any common metal member shape, such as cylindrical or columnar, without any particular restrictions.

[0044] On the other hand, the second member 30 is not particularly limited as long as it is a member that can be suitably joined with the alloy material (W-Pt-Cu alloy) 10, and various members can be used without particular restriction. A suitable example of such a second member 30 is a dissimilar metal member whose main component is a metal element other than tungsten. An example of such a dissimilar metal member is a metal member containing Cu or Pt. Specific examples of such dissimilar metal members include Cu members, Pt members, and Pt-Cu alloy members. Furthermore, the dissimilar metal member may be a metal member that has good bonding properties to Cu or Pt (such as a Ni member or a Co member). Note that the material of the second member 30 can be appropriately changed according to the main component of the Pt-Cu phase 14 of the alloy material 10, and is not limited to the metal members that have good bonding properties to Cu or Pt as described above. For example, in the manufacture of alloy materials described later, a Pt-Cu phase 14 containing a third metal element other than Pt or Cu (e.g., Au, Ni, Zn, etc.) can be formed by mixing the third metal element into the Cu source. When such a Pt-Cu phase 14 containing a third metal element is formed, a metal member with good bonding compatibility with the third metal element can be used for the second member 30. As an example, when a Pt-Cu phase 14 containing Au is formed, in addition to the Cu member, Pt member, and Pt-Cu alloy member mentioned above, Au members, Ag members, etc. can be used as bonding targets. Furthermore, the term "dissimilar metal member" in this specification refers to a metal member whose main component is a metal element other than tungsten, and there is no intention to exclude metal members containing W as a minor component. That is, the dissimilar metal member may also be an alloy containing tungsten.

[0045] Furthermore, the second member 30 is not limited to dissimilar metal members as described above. For example, the alloy material 10 disclosed herein is not limited to joining a W member to a dissimilar metal member, but can also be used as a joining material to join W members to each other. That is, the second member 30 may be the same type of W member as the first member 20 described above (for example, tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, etc., and composite materials containing these). Generally, W members are difficult to weld directly because they have a high melting point. However, by using the alloy material disclosed herein, W members can be easily joined to each other. Furthermore, the second member 30 does not have to be a metal member. For example, the second member 30 may be a ceramic such as tria (ThO2) or yttria, or glass. The alloy material 10 disclosed herein can exhibit suitable bonding properties even to such non-metallic members.

[0046] 3. Method for manufacturing alloy materials Next, a method for manufacturing the alloy material disclosed herein will be described. The alloy material disclosed herein can be manufactured by preparing a Pt-W alloy containing Pt and W, and a Cu source containing copper (Cu) as precursor materials, and transferring Pt from the Pt-W alloy to the Cu source. As an example, such transfer of Pt from the Pt-W alloy to the Cu source occurs by bringing the Pt-W alloy and the Cu source into contact. Specifically, when the Pt-W alloy and the Cu source are brought into contact, Pt diffuses (moves) from the Pt-W alloy to the Cu source. At this time, diffusion of Pt is likely to occur at the grain boundaries between the crystal grains of the Pt-W alloy and Cu, so the diffusion of Pt proceeds while the crystal grains of the Pt-W alloy and Cu are finely mixed. As a result, a ternary two-phase alloy material (W-Pt-Cu alloy) is produced, which consists of a Pt-Cu phase containing Pt and Cu, and a W phase remaining after Pt removal from the Pt-W alloy.

[0047] Here, to produce a W-Pt-Cu alloy, it is sufficient to transfer Pt from a Pt-W alloy to Cu, and the specific procedure is not particularly limited. In other words, the method for producing the alloy material disclosed herein encompasses multiple methods with different specific procedures (steps). Below, an example of the manufacturing method disclosed herein (the first embodiment) will be described.

[0048] (1) First Embodiment The manufacturing method according to this embodiment comprises a Pt-W alloy formation step and a W-Pt-Cu alloy formation step. Each of these steps will be described below.

[0049] (a) Pt-W alloy production process In this process, a heat treatment is performed while a Pt source containing platinum (Pt) and a W source containing tungsten (W) are in contact. This makes it easy to produce a Pt-W alloy, which is a precursor to a W-Pt-Cu alloy. The Pt-W alloy produced in this process is not particularly limited as long as it contains Pt and W. An example of such a Pt-W alloy is an intermetallic compound containing Pt and W in a predetermined integer ratio (e.g., Pt2W). Because this type of intermetallic compound has very fine crystal grains, by using it as a precursor to a W-Pt-Cu alloy, an alloy material in which the W phase and Pt-Cu phase are finely mixed can be produced. Specifically, the crystal grain size of the Pt-W alloy is D 50 The particle size is suitable if it is 2000 nm or less, preferably 1500 nm or less, more preferably 1000 nm or less, even more preferably 500 nm or less, and particularly preferably 200 nm or less. On the other hand, the D of the crystal grains of the Pt-W alloy 50 The lower limit of the particle size is not particularly limited and may be 40 nm or larger, 60 nm or larger, 80 nm or larger, or 100 nm or larger.

[0050] The W source used in this process can be any material containing the element W, and its detailed composition and form are not particularly limited. Examples of such W sources include powder materials containing tungsten particles, solid or solution compounds containing tungsten, and solid metal members containing tungsten. Since the material of such a W source is the same type as that of the first member (W member) 20 described above, a redundant explanation will be omitted. Furthermore, as will be described in more detail later, the manufacturing method disclosed herein allows for the production of the alloy material 10 (see Figure 1) alone, or for the production of the alloy material 10 attached to the W member 20 (see Figure 2). Although not intended to limit the manufacturing method disclosed herein, when producing the alloy material 10 alone, it is preferable to use a tungsten thin film with a thickness of 50 μm or less as the W source. This ensures that the entire W source is used to form the alloy material 10, thus allowing for the formation of a standalone alloy material 10 without any attached tungsten members. Such a tungsten thin film can be formed, for example, by chemical vapor deposition or physical vapor deposition. Furthermore, from the viewpoint of more reliably forming the single alloy material 10, the thickness of the tungsten thin film is more preferably 20 μm or less, even more preferably 10 μm or less, and particularly preferably 5 μm or less. Also, from the viewpoint of preventing poor formation of the Pt-W alloy due to a lack of W, the lower limit of the thickness of the tungsten thin film is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.5 μm or more, and particularly preferably 1 μm or more.

[0051] On the other hand, the Pt source can be any material containing the element Pt, and its detailed composition and form are not particularly limited. An example of such a Pt source is a Pt paste obtained by dispersing Pt powder in a predetermined solvent. A Pt-W alloy can be easily produced by applying such a Pt paste to the surface of a W source and then performing a heat treatment. Such a Pt paste is not particularly limited except that it contains Pt particles, and conventionally known Pt pastes can be used as long as they do not hinder the effects of the technology disclosed herein. For example, the average particle size of the Pt particles in the paste is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 5 μm, particularly preferably 0.1 μm to 1.0 μm, and for example, 0.5 μm. In this specification, "average particle size" is the average value of the particle sizes of a plurality (e.g., 100) of particles measured based on SEM observation. Furthermore, when the total volume of the Pt paste is 100 vol%, the Pt particle content (volume ratio) is preferably 1 vol% or more, more preferably 2.5 vol% or more, even more preferably 5 vol% or more, and particularly preferably 7.5 vol% or more. This prevents poor formation of Pt-W alloy due to insufficient Pt. On the other hand, from the viewpoint of suppressing the increase in viscosity of the Pt paste and improving workability, the upper limit of the Pt particle content (volume ratio) is preferably 20 vol% or less, more preferably 17.5 vol% or less, even more preferably 15 vol% or less, and particularly preferably 12.5 vol% or less. When the total weight of the Pt paste is 100 wt%, the Pt particle content (weight ratio) is preferably 50 wt% or more, more preferably 55 wt% or more, even more preferably 60 wt% or more, and particularly preferably 65 wt% or more. On the other hand, the upper limit of the Pt particle content (by weight) is preferably 90 wt% or less, more preferably 85 wt% or less, even more preferably 80 wt% or less, and particularly preferably 75 wt% or less. Note that the components of the Pt paste other than the Pt particles (solvent, binder, dispersant, etc.) can be conventionally known components without particular restriction, as long as they do not hinder the effects of the disclosed technology, and therefore a detailed explanation is omitted as they do not characterize the disclosed technology.

[0052] Furthermore, from the viewpoint of preventing poor formation of Pt-W alloy due to a lack of Pt, the coating thickness of the Pt paste in this process is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and particularly preferably 40 μm or more. On the other hand, the upper limit of the coating thickness of the Pt paste is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, and particularly preferably 60 μm or less. This prevents unreacted Pt from forming on the surface of the Pt-W alloy and hindering the reaction between the Pt-W alloy and the Cu source in the W-Pt-Cu alloy formation process described later. The coating thickness of the Pt paste can be easily controlled to the desired thickness by adjusting the thickness of the metal mask used when applying the paste.

[0053] Furthermore, the heating temperature in this process is preferably 750°C or higher, more preferably 800°C or higher, even more preferably 850°C or higher, and particularly preferably 900°C or higher. This improves the efficiency of Pt-W alloy formation. On the other hand, the upper limit of the heating temperature in this process is preferably 1250°C or lower, more preferably 1200°C or lower, even more preferably 1150°C or lower, and particularly preferably 1100°C or lower. Furthermore, the heating time in this process is preferably 0.5 hours or more, more preferably 1 hour or more. This allows for the proper formation of Pt-W alloy. On the other hand, from the viewpoint of manufacturing efficiency, the upper limit of the heating time in this process is preferably 5 hours or less, more preferably 4 hours or less, and particularly preferably 3 hours or less. In this specification, "heating temperature" refers to the maximum temperature during the heat treatment, and "heating time" refers to the time during which the maximum temperature is maintained. Furthermore, it is preferable to set the atmosphere during the heat treatment to a non-oxidizing atmosphere (neutral atmosphere, reducing atmosphere). Examples of reducing gases include hydrogen (H2) gas and hydrocarbon gases (such as CH4 and C3H8). An example of a neutral gas is nitrogen (N2) gas. Furthermore, mixtures of these reducing and neutral gases can also be used. For example, a mixed gas obtained by combining hydrogen (H2) gas with nitrogen (N2) gas at a concentration of 1% to 5% (e.g., 3%) can be used.

[0054] Furthermore, from the viewpoint of preventing damage (such as cracks) due to rapid volume changes during heat treatment, it is preferable to perform a drying treatment to dry the Pt paste before the heat treatment for forming the Pt-W alloy. The heating temperature in this drying treatment is preferably 60°C or higher, more preferably 80°C or higher, and particularly preferably 100°C or higher. On the other hand, from the viewpoint of preventing the cracks mentioned above, the upper limit of the heating temperature in the drying treatment is preferably 140°C or lower, and more preferably 130°C or lower. In addition, the drying time is preferably 10 minutes or more and 60 minutes or less (for example, about 30 minutes).

[0055] Furthermore, if organic components such as binders are added to the Pt paste, a preheating treatment (binder removal treatment) may be performed to remove the organic components before the heat treatment for forming the Pt-W alloy. However, if the W source oxidizes and tungsten oxide is produced as a result of this binder removal treatment, the formation of the Pt-W alloy may be inhibited. For this reason, the organic components (binders, etc.) added to the Pt paste are preferably resin materials (e.g., acrylic resin) that can be sufficiently decomposed by heating in a non-oxidizing atmosphere. From the viewpoint of reliably removing organic components, the heating temperature in the binder removal treatment is preferably 145°C or higher, more preferably 150°C or higher, even more preferably 155°C or higher, and particularly preferably 160°C or higher. On the other hand, in order to prevent the formation of the Pt-W alloy from progressing during the binder removal treatment, the upper limit of the heating temperature in the binder removal treatment is preferably 500°C or lower, more preferably 450°C or lower, even more preferably 400°C or lower, and particularly preferably 350°C or lower. Furthermore, the heating time in the binder removal process is preferably 0.5 hours or more, and more preferably 1 hour or more. This ensures the reliable removal of organic components. On the other hand, from the viewpoint of manufacturing efficiency, the upper limit of the heating time in the binder removal process is preferably 5 hours or less, more preferably 4 hours or less, even more preferably 3 hours or less, and particularly preferably 2 hours or less.

[0056] (b) W-Pt-Cu alloy formation process In this process, a heat treatment is performed while the Cu source, a material mainly containing Cu, and the Pt-W alloy are in contact. This causes rapid migration (typically diffusion) of Pt from the Pt-W alloy to Cu. During this process, Pt diffusion proceeds while the crystal grains of the Pt-W alloy and Cu become finely intermingled. On the other hand, W in the Pt-W alloy hardly dissolves with Cu. Therefore, de-Pt from the Pt-W alloy to Cu proceeds, and a W phase, in which W is the main component, is formed. Meanwhile, as Pt is supplied to Cu, a Pt-Cu phase is formed so as to fill the area around the W phase. Thus, according to the manufacturing method of this embodiment, it is possible to produce a ternary two-phase alloy material (W-Pt-Cu alloy) in which W and Cu, which would not normally form an alloy, are mixed.

[0057] As mentioned above, when a Cu source and a Pt-W alloy are brought into contact, Pt moves (diffuses) from the Pt-W alloy to Cu, so a W-Pt-Cu alloy can be produced without heat treatment. However, when a W-Pt-Cu alloy production process involving heat treatment is carried out as in this embodiment, the diffusion of Pt to Cu proceeds rapidly, so the production efficiency of the W-Pt-Cu alloy can be greatly improved. The maximum temperature in such heat treatment is preferably 750°C or higher, more preferably 800°C or higher, even more preferably 850°C or higher, and particularly preferably 900°C or higher. This more effectively promotes the diffusion of Pt and allows for the efficient formation of the W-Pt-Cu alloy. On the other hand, the upper limit of the maximum firing temperature is preferably 1500°C or lower, more preferably 1400°C or lower, even more preferably 1300°C or lower, and particularly preferably 1200°C or lower. The firing time in this process is preferably 1 hour or more, and more preferably 1.5 hours or more. This allows for the formation of a W-Pt-Cu alloy in which the W phase and Pt-Cu phase are sufficiently mixed. On the other hand, from the viewpoint of manufacturing efficiency, the upper limit of the firing time in this process is preferably 3 hours or less, and more preferably 2.5 hours or less.

[0058] Furthermore, it is preferable to set the firing atmosphere in this process to a non-oxidizing atmosphere (e.g., a neutral atmosphere, an inert atmosphere, or a reducing atmosphere). Examples of reducing gases include hydrogen (H2) gas and hydrocarbon gases (CH4, C3H8, etc.). Examples of inert gases include argon (Ar) gas, and examples of neutral gases include nitrogen (N2) gas and ammonia. It is also possible to use a mixture of a reducing gas and an inert gas (or neutral gas). For example, a mixed gas obtained by mixing hydrogen gas with nitrogen gas at a concentration of 1% to 5% (e.g., 3%) can be used.

[0059] Furthermore, in this process, 0.5 g / mm³ is applied so as to sandwich the Pt-W alloy and the Cu source. 2 (more preferably 1 g / mm³) 2 In particular, 1.5 g / mm³ is preferred. 2 It is preferable to perform the firing process while applying the load (as described above). This prevents gaps from forming between the Cu source and the Pt-W alloy, and allows for more efficient formation of the W-Pt-Cu alloy. The upper limit of the load applied to the Pt-W alloy and the Cu source is not particularly limited, but is 10 g / mm². 2 It may also be less than 8 g / mm 2 It may also be less than 6 g / mm 2 It may also be less than 5 g / mm 2 The following is also acceptable.

[0060] The Cu source used in this process can be any material containing Cu, and its composition is not particularly limited. Specifically, the Cu source is not limited to Cu and may contain other metallic elements. In this case, by mixing a third metallic element other than Pt or Cu into the Cu source, the Pt-Cu phase of the W-Pt-Cu alloy after production can be made to contain the third metallic element. This improves the bonding properties to dissimilar metal components whose main components are metallic elements other than Cu or Pt. Examples of third metallic elements that can be mixed into the Cu source include gold (Au), nickel (Ni), aluminum (Al), tin (Sn), zinc (Zn), silica (Si), iron (Fe), manganese (Mn), cobalt (Co), and beryllium (Be).

[0061] On the other hand, the shape of the Cu source is not particularly limited and may be a solid metal member containing Cu (Cu member), or a Cu paste obtained by dispersing Cu powder in a solvent. For example, when manufacturing only the alloy material, it is preferable to use a copper paste coated to a certain thickness or less as the Cu source. This ensures that all of the Cu source is used to form the alloy material, thus enabling the formation of a standalone alloy material without any attached copper member. Alternatively, instead of copper paste, a thin copper film may be formed, for example, by chemical vapor deposition. From the viewpoint of reliably forming a standalone alloy material, the thickness of the Cu source is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, and particularly preferably 60 μm or less. On the other hand, from the viewpoint of preventing poor formation of W-Pt-Cu alloy due to insufficient Cu, the lower limit of the thickness of the Cu source is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and particularly preferably 40 μm or more.

[0062] When using Cu paste as the Cu source, the average particle size of the Cu particles in the paste is preferably 0.01 μm to 10 μm, more preferably 0.1 μm to 5 μm, and particularly preferably 0.5 μm to 2 μm, for example, 1 μm. Furthermore, the Cu particle content (volume ratio) when the total volume of the Cu paste is 100 vol% is preferably 5 vol% or more, more preferably 10 vol% or more, even more preferably 15 vol% or more, and particularly preferably 20 vol% or more. This prevents poor formation of the Pt-W alloy due to insufficient Cu. On the other hand, from the viewpoint of suppressing the increase in viscosity of the copper paste and improving workability, the upper limit of the Cu particle content (volume ratio) is preferably 55 vol% or less, more preferably 50 vol% or less, even more preferably 45 vol% or less, and particularly preferably 40 vol% or less. Furthermore, when the total weight of the Cu paste is 100 wt%, the Cu particle content (by weight) is preferably 60 wt% or more, more preferably 65 wt% or more, even more preferably 70 wt% or more, and particularly preferably 75 wt% or more. On the other hand, the upper limit of the Cu particle content (by weight) is preferably 95 wt% or less, more preferably 90 wt% or less, and particularly preferably 85 wt% or less. Regarding the components of the Cu paste other than the Cu particles (solvents, binders, dispersants, etc.), conventionally known components can be used without particular restriction as long as they do not hinder the effects of the disclosed technology, and since they do not characterize the disclosed technology, a detailed explanation is omitted. Also, as mentioned above, when adding a third metal element to the Cu source, it is preferable to add the powder of the third metal element to the Cu paste. This allows for easy addition of the third metal element to the Cu source.

[0063] (2) Second embodiment Next, another example of a method for manufacturing the alloy material disclosed herein (a second embodiment) will be described.

[0064] In the first embodiment described above, a W-Pt-Cu alloy is produced by performing two or more heat treatments, including a Pt-W alloy formation step and a W-Pt-Cu alloy formation step. However, the manufacturing method disclosed herein is not limited to the above embodiment. For example, experiments have confirmed that a W-Pt-Cu alloy can be produced even when a Pt source is interposed between the W source and the Cu source and the heat treatment is performed together. Specifically, as in this embodiment, when the W source, Pt source, and Cu source are heated together, a Pt-W alloy is formed at the boundary between the W source and the Pt source. As the heat treatment progresses further, the Pt-W alloy and Cu (including the Pt-Cu alloy) become finely intermingled, and the Pt in the Pt-W alloy moves to Cu. As a result, a W-Pt-Cu alloy is formed between the W source and the Cu source, in which the W phase and the Pt-Cu phase are mixed. Furthermore, from the viewpoint of reliably manufacturing W-Pt-Cu alloy, it is preferable to perform the Pt-W alloy production process in advance to reliably produce a precursor material (Pt-W alloy), as in the first embodiment described above, before producing the W-Pt-Cu alloy. On the other hand, considering manufacturing efficiency and cost, it is preferable to produce the Pt-W alloy and the W-Pt-Cu alloy simultaneously, as in this embodiment.

[0065] Furthermore, the heat treatment temperature in this embodiment is preferably 750°C or higher, more preferably 800°C or higher, even more preferably 850°C or higher, and particularly preferably 900°C or higher. This more effectively promotes the diffusion of Pt and efficiently forms the W-Pt-Cu alloy. On the other hand, the upper limit of the maximum firing temperature is preferably 1500°C or lower, more preferably 1400°C or lower, even more preferably 1300°C or lower, and particularly preferably 1200°C or lower. Also, the firing time in this process is preferably 1 hour or more, and more preferably 1.5 hours or more. This allows for the formation of a W-Pt-Cu alloy in which the W phase and Pt-Cu phase are sufficiently mixed. On the other hand, from the viewpoint of manufacturing efficiency, the upper limit of the firing time in this process is preferably 3 hours or less, and more preferably 2.5 hours or less.

[0066] Furthermore, in this embodiment, in the heat treatment described above, 0.5 g / mm³ is added so as to sandwich the W source and the Cu source.2 (more preferably 1 g / mm³) 2 In particular, 1.5 g / mm³ is preferred. 2 It is preferable to perform the firing process while applying the load described above. This prevents gaps from forming between each of the Cu, Pt, and W components, and allows for more efficient formation of the W-Pt-Cu alloy. The upper limit of the load applied when sandwiching each component is not particularly limited, but is 10 g / mm². 2 It may also be less than 8 g / mm 2 It may also be less than 6 g / mm 2 It may also be less than 5 g / mm 2 The following is also acceptable.

[0067] 4. Other Embodiments An embodiment of the technology disclosed herein has been described above. However, the above-described embodiment is not intended to limit the technology disclosed herein, and various modifications can be made.

[0068] For example, the various conditions described in each of the embodiments described above are examples of conditions for manufacturing alloy materials alone and are not intended to limit the technology disclosed herein. Depending on the shape and state of the target alloy material, various conditions such as the W source, Cu source, Pt source, firing temperature, and firing time can be appropriately adjusted. As a specific example, in the embodiments described above, W paste or W thin film is used as the W source and Cu paste or Cu thin film is used as the Cu source in order to manufacture alloy materials alone. However, by using a tungsten member having a predetermined thickness as the W source, it is possible to manufacture an alloy material that is joined to a tungsten member. This configuration is preferable from the viewpoint of work efficiency, as the manufacturing of the alloy material and the joining process between the alloy material and the tungsten member can be carried out simultaneously. Furthermore, if the thickness of the tungsten member is 0.1 mm or more (preferably 0.2 mm or more, more preferably 0.3 mm or more), the tungsten member remains even after the W-Pt-Cu alloy is formed, so an alloy material that is joined to a tungsten member can be obtained.

[0069] Similarly, when the dissimilar metal members to be joined are Cu members, an alloy material can be manufactured in a state where it is joined with the Cu member (dissimilar metal member) by using a copper member having a predetermined thickness as the Cu source, which is preferable from the viewpoint of work efficiency, etc. Furthermore, if the thickness of the copper member is 0.1 mm or more (preferably 0.2 mm or more, more preferably 0.3 mm or more), the copper member will remain even after the W-Pt-Cu alloy is formed, and an alloy material can be obtained in a state where it is joined with the copper member.

[0070] Furthermore, by using a tungsten member having a predetermined thickness as the W source and a copper member having a predetermined thickness as the Cu source, a joint can be manufactured in which a W member and a Cu member are joined via a W-Pt-Cu alloy. According to this manufacturing method, a desired joint can be manufactured efficiently. It should be noted that the joint manufactured in this way does not necessarily have to be composed entirely of a W-Pt-Cu alloy formed between the W member and the Cu member. For example, a Pt-W alloy may be formed in the region of the alloy material on the W member side, or a Pt-Cu alloy may be formed in the region on the Cu member side.

[0071] Furthermore, in each of the embodiments described above, the Pt-W alloy and the Cu source are in direct contact. However, the manufacturing method disclosed herein is not limited to these embodiments, and the Pt-W alloy and the Cu source may be brought into contact with other metal members (intermediate metal members) interposed therebetween. The inventors have experimentally confirmed that even in such cases, the movement of Pt from the Pt-W alloy to Cu occurs, and a W-Pt-Cu alloy is formed. An example of such an intermediate metal member is a metal member containing Pt. The intermediate metal member is preferably a metal member that diffuses the Cu component. For example, in addition to Pt, metals or alloys that can alloy (especially solid solution) with Cu can be used. Specific examples of intermediate metal members include metal members containing Ni, Au, Sn, Zn, etc., and copper alloys. Among these, Ni, Au, and Pt, which can form a complete solid solution with Cu, are particularly suitable as intermediate metal members. Also, as with the embodiments described above, it is preferable to perform heat treatment even when an intermediate metal member is interposed. This promotes the migration of Pt from the Pt-W alloy to Cu. Note that the heat treatment conditions can be set to the same extent as in the embodiment described above, so a redundant explanation is omitted.

[0072] Furthermore, in the embodiments described above, the alloy material disclosed herein is used as a bonding material between a tungsten member and a dissimilar metal member. However, the alloy material disclosed herein is not limited to bonding materials and is expected to have applications in various fields. Other examples of applications of the alloy material disclosed herein include barrier films that protect the surface of metal members (e.g., W members) and catalysts. In addition, of the W phase and Pt-Cu phase that constitute the alloy material disclosed herein, the Pt-Cu phase is more easily soluble in acid. Therefore, by manufacturing an alloy material in which a very fine W phase exists in the matrix of the Pt-Cu phase, and dissolving the Pt-Cu phase of this alloy material in acid, very fine tungsten particles can be manufactured. In other words, the alloy material disclosed herein can also be used for the manufacture of tungsten particles.

[0073] [Example Test] The following describes test examples relating to the present invention, but these test examples are not intended to limit the present invention.

[0074] A. First test In this study, as in the first embodiment described above, a W-Pt-Cu alloy was produced by performing a Pt-W alloy formation process and a W-Pt-Cu alloy formation process. Various analyses were then performed in each process to investigate the formation mechanism of the W-Pt-Cu alloy.

[0075] 1.Pt-W alloy production process First, a Pt paste was prepared by mixing Pt powder with an average particle size of 0.5 μm, a binder (acrylic resin), and a solvent (IBA: isobutyl alcohol). The Pt powder content of this Pt paste was set to 70 wt% (10 vol%) by volume relative to the total weight of the Pt paste. Next, this Pt paste was applied to the surface of a tungsten plate (W plate) using a metal mask (thickness 50 μm × 20 mm × 20 mm). Then, a drying treatment (drying temperature: 120 °C, drying time: 30 minutes) was performed to dry the Pt paste on the surface of the W plate. Finally, the W plate with the dried Pt paste attached was subjected to a heat treatment to obtain sample A-1 for analysis. The atmosphere during the heat treatment was set to a reducing atmosphere (N2-H2 (3%) gas). Furthermore, in this process, the heat treatment was carried out under the conditions of heating to 400°C at a heating rate of 4°C / min and holding for 1 hour, followed by heating to 1000°C at a heating rate of 4°C / min and holding for 2 hours.

[0076] The heat-treated sample A-1 was thinned using a focused ion beam scanning electron microscope (FIB-SEM), and cross-sectional SEM images of the cut surface were acquired (see Figure 3). In this study, EDX analysis was performed on the acquired cross-sectional SEM image (Figure 3(b)) to obtain elemental mapping images of W and Pt (see Figure 4). In Figure 4, (a) is the elemental map of W, and (b) is the elemental map of Pt. From the results of these analyses, it was found that the heat-treated sample A-1 comprises a W plate and a Pt-W alloy formed on the surface of the W plate.

[0077] Furthermore, in this experiment, EDX spectra were obtained for region α (W plate portion) and region β (Pt-W alloy portion) in Figure 3(b). The EDX spectrum of region α is shown in Figure 5(a), and the EDX spectrum of region β is shown in Figure 5(b). Based on these EDX spectra, the elemental abundance ratios in each region were analyzed. As a result, in region α (W plate portion), the results were confirmed to be Pt: 0 atm%, W: 99.05 atm%, and Fe: 0.95 atm%. On the other hand, in region β (Pt-W alloy portion), the results were confirmed to be Pt: 64.52 atm%, W: 34.30 atm%, and Fe: 1.18 atm%. Furthermore, in this experiment, EDX line analysis was performed on the 7000 nm long line segment X drawn in Figure 3(b) to investigate the changes in elemental concentrations (atm%) of W and Pt. The results are shown in Figure 6. As shown in Figure 6, the amount of W element, which was approximately 100 atm% in region α (W plate portion), decreased to about 33 atm% in region β (Pt-W alloy portion). On the other hand, in region β, the amount of Pt element increased to 66 atm%. In addition, in this test, electron diffraction was performed in each region, region α (W plate portion) and region β (Pt-W alloy portion) in Figure 3(b). The results are shown in Figure 7. In Figure 7, (a) is an image showing the results of electron diffraction in region α (W plate portion), and (b) is an image showing the results of electron diffraction in region β (Pt-W alloy portion). In this electron diffraction, a diffraction pattern for W was obtained in region α, and in region β, a diffraction pattern at least on the 011 plane of Pt2W was obtained. From these analysis results, it was found that the Pt-W alloy produced in this process is an intermetallic compound (Pt2W) in which Pt and W are mixed in an integer ratio of 2:1.

[0078] Next, the crystal structure of the sample A-1 was analyzed using EBSD on an SEM image. The SEM / EBSD image of the analysis results is shown in Figure 8. Furthermore, (c) in Figure 8 shows the tungsten and Pt2W in the SEM / EBSD image of Figure 8(b) colored. In addition, based on the results of this EBSD analysis, the particle size of the crystal grains in each region of the W plate and the Pt-W alloy was measured. Specifically, the equivalent circular diameter of the crystal grains in the image was measured in each region of the W plate and the Pt-W alloy, and a number-based particle size distribution was created. The results are shown in Figure 9. Note that (a) in Figure 9 is the particle size distribution of the crystal grains in the W plate, and (b) is the particle size distribution of the crystal grains in the Pt-W alloy. From these analysis results, it was found that the Pt-W alloy (Pt2W) formed on the W plate is composed of extremely fine crystal grains of several hundred nanometers.

[0079] 2.W-Pt-Cu alloy production process In this process, a Cu paste was prepared by mixing Cu powder with an average particle size of 1 μm, a binder (acrylic resin), and a solvent (IBA: isobutyl alcohol). The Cu powder content of this Cu paste was set to 80 wt% (30 vol%) by volume relative to the total weight. The Cu paste was then applied to the Pt-W alloy side surface of the analysis sample A-1 using a metal mask (thickness 50 μm × 20 mm × 20 mm). Next, a drying treatment (drying temperature: 120°C, drying time: 30 minutes) was performed to dry the Cu paste on the surface of analysis sample A-1, and then a heat treatment was performed to prepare analysis sample A-2. The atmosphere for the heat treatment was set to a reducing atmosphere (N2-H2 (3%) gas). Furthermore, in this process, the heat treatment was carried out under the conditions of heating to 400°C at a heating rate of 4°C / min and holding for 1 hour, followed by heating to 1000°C at a heating rate of 4°C / min and holding for 2 hours.

[0080] In the analysis of this process, first, the analysis sample A-2 after heat treatment was thinned using FIB-SEM. Then, cross-sectional SEM images of the cut surface were taken. The results are shown in Figure 10. Next, the crystal structure of analysis sample A-2 was analyzed using EBSD. The results are shown in Figure 11. As shown in Figure 11(b), it was found that analysis sample A-2 had a W-Pt-Cu alloy in which W phase and Pt-Cu phase were mixed. It was found that both the W phase and Pt-Cu phase were composed of minute crystal grains. As shown in Figure 11(c), it was found that the Pt-Cu phase had a random crystal orientation and was composed of particularly minute crystal grains. On the other hand, as shown in Figure 11(d), it was found that the W phase was composed of larger crystal grains than the Pt-Cu phase, and the crystal orientation of these crystal grains was oriented in the

[0101] direction.

[0081] Furthermore, in this test, the particle size of the crystal grains in the W-Pt-Cu alloy was measured based on the EBSD analysis results described above. Here, the equivalent circular diameter of the crystal grains constituting each phase, the W phase and the Pt-Cu phase, was measured within the observation field, and the particle size distribution in each phase was determined. The results are shown in Figure 12. Note that Figure 12(a) shows the particle size distribution of the Pt-Cu phase, and (b) shows the particle size distribution of the W phase. As shown in Figure 12, the D 50 The particle size is 621 nm, and it is a Pt-Cu phase D 50 The particle size was 102 nm, and it was found that both the W phase and the Pt-Cu phase consisted of very fine crystal grains. From the particle size distribution shown in Figure 12 and the SEM / EBSD image shown in Figure 11, it is inferred that the W-Pt-Cu alloy formed on the analysis sample A-2 has a morphology in which very fine crystal grains of the Pt-Cu phase are filled between relatively large crystal grains of the W phase. In other words, from this analysis, it is understood that the W-Pt-Cu alloy is formed by the migration (diffusion) of Pt in the Pt2W alloy to Cu while Pt2W alloy and Cu are mixed together.

[0082] B. Second Examination In this test, as in the second embodiment described above, a heat treatment was performed on the W source and the Cu source with a Pt source interposed between them. Various analyses were then performed on the resulting alloy material.

[0083] 1. Sample preparation First, a plate-shaped tungsten material (thickness 0.3 mm, length 7.5 mm, width 7.5 mm) was prepared as the W source. Then, a Pt paste was prepared as the Pt source, and this Pt paste was applied to the entire surface of one side of the tungsten material. The Pt paste used in this test was prepared by mixing 21 vol% Pt powder (average particle size: 0.5 μm), a binder (ethyl cellulose resin), a dispersant, and a solvent. The solvent used for the Pt paste was 2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutyrate. In this test, the Pt paste was dried by drying at 120°C for 30 minutes, and then debindered in air (200°C for 3 hours).

[0084] Next, a plate-shaped copper member (0.3 mm thick, 20 mm long, 20 mm wide) was prepared as the copper source. The paste-coated surface of the tungsten member and the copper member were brought into surface contact, and a 50 g alumina block was placed on top of the tungsten member, thereby applying a pressure of 0.89 kPa to the contact area between the tungsten and copper members. In this state, a firing process was carried out with a heating rate of 4 °C / min, a maximum firing temperature of 1000 °C, and a firing time of 2 hours to obtain a bonded body (Sample 1) in which the tungsten and copper members were joined. N2 gas containing 3% hydrogen (H2) was used as the atmospheric gas during firing.

[0085] 2. Sample Analysis (1) SEM observation and EDX analysis After cutting the assembled sample 1 along the stacking direction, the cut surface was polished using ion milling, and a cross-sectional SEM image of the cut surface was acquired. EDX analysis was then performed on the acquired cross-sectional SEM image to obtain elemental mapping images of tungsten (W), copper (Cu), and platinum (Pt). The analysis results at a magnification of 250x are shown in Figure 13, the analysis results at a magnification of 1000x are shown in Figure 14, the analysis results at a magnification of 10000x are shown in Figure 15, and the analysis results at a magnification of 50000x are shown in Figure 16. In Figures 13 to 16, (a) is the cross-sectional SEM image, (b) is the elemental map of W, (c) is the elemental map of Cu, and (d) is the elemental map of Pt.

[0086] First, as shown in Figure 13, observation at a low magnification of 250x revealed an alloy layer (Pt-Cu layer) mainly composed of a Pt-Cu alloy between the tungsten member and the copper member. Although such Pt-Cu alloys usually have poor bonding properties to tungsten members, in the joint of Sample 1, the Pt-Cu layer and the tungsten member appeared to be strongly bonded. Therefore, as shown in Figure 14, observation of the boundary between the Pt-Cu layer and the tungsten member at a higher magnification (1000x) revealed that a layer containing a mixture of W, Pt, and Cu (W-Pt-Cu layer) was formed at the boundary between the tungsten member and the Pt-Cu alloy layer. Further magnification of this W-Pt-Cu layer revealed a W-Pt-Cu alloy in which the W phase was mixed within the Pt-Cu phase matrix, as shown in Figures 15 and 16. From the above analysis results, it was found that a W-Pt-Cu alloy can be produced even when a Pt source is interposed between the W source and the Cu source and the heat treatment is performed together. Furthermore, it was found that this W-Pt-Cu alloy can be used to firmly bond tungsten and copper components, which were previously difficult to join.

[0087] (2) Measurement of the number of atoms Next, in this test, cross-sectional SEM images at a magnification of 50,000x, as shown in Figure 16(a), were acquired in five fields of view in the region where the above-mentioned W-Pt-Cu alloy was formed. Then, the number of W, Pt, and Cu atoms in each field of view was measured by EDX compositional analysis, and the average values ​​were calculated. As a result, the average number of W atoms in the W-Pt-Cu alloy formed in Sample 1 was 34 atm%, and the average number of Pt-Cu atoms was 66 atm%. In addition, the ratio of Pt to Cu in the Pt-Cu alloy was 14.6:85.4.

[0088] (3) Elemental analysis by region In addition, in this study, EDX analysis was performed at each point from point 1 to point 6 in the 1000x magnification SEM image of sample 1 (see Figure 17), and the ratio (atm%) of W, Pt, and Cu atoms was measured. The measurement results are shown in Table 1 below.

[0089] [Table 1]

[0090] As shown in Figure 17 and Table 1, point 1 in Sample 1 is a tungsten component, point 2 is a W-Pt-Cu layer, points 3-5 are Pt-Cu layers, and point 6 is a copper component. Looking at Table 1, it can be seen that the Pt / Cu ratio decreases from point 1 to point 6 (the Pt / Cu ratio is higher closer to point 1). From this, it can be assumed that in the initial stages of firing, a Pt-W alloy was formed in the region close to the tungsten component (near point 2), and as a result of Pt diffusing from this Pt-W alloy toward the copper component (point 6), a W-Pt-Cu layer was formed at point 2 adjacent to the tungsten component. Furthermore, in the region far from the tungsten component (points 3-4), since no Pt-W alloy was formed, it can be assumed that a Pt-Cu alloy, a mixture of Pt and Cu, was formed. It should be noted that in metal joint components where the number of Cu atoms changes sequentially in this way, the effect of relaxing thermal stress at the joint can be expected.

[0091] (4) Measurement of the area of ​​the W phase In this study, the area of ​​the W phase was measured by analyzing the cross-sectional SEM image of Sample 1. Image analysis was performed using ImageJ 1.52a, image analysis software from the National Institutes of Health (NIH). Specifically, Figure 15(a) (SEM image at 10,000x magnification) was binarized and inverted to black and white so that the W phase was displayed in black and the Pt-Cu phase in white. The area of ​​the W phase was then measured by counting the black dots within a 5 μm × 7.5 μm field of view. As a result, within the matrix of the white-displayed Pt-Cu phase, an area of ​​0.007 μm was found. 2 ~1.02μm 2 85 W-phase regions were identified within this range. The area of ​​each of the 85 identified W-layer regions is shown in Table 2 below. In other words, in the W-Pt-Cu alloy in Sample 1, the area was 0.007 μm². 2 ~1.02μm 2 The W phase in this range is approximately 2.3 locations / μm 2 It was found to exist at a density of . Furthermore, the average area of ​​the W phase in the above field of view was 0.113 μm². 2 The maximum area of ​​the W phase was 1.02 μm². 2 The minimum value is 0.007 μm. 2 That was the case.

[0092] [Table 2]

[0093] (5) Observation of crystal structure Sample 1 was thinned using FIB-SEM and SEM / EBSD images were acquired. The results are shown in Figure 18. As shown in Figure 18, in Sample 1, a Pt-Cu alloy was formed between the tungsten member and the copper member, and a W-Pt-Cu alloy was formed at the boundary between the Pt-Cu alloy and the tungsten member. Furthermore, it was confirmed that the crystal grains of W were smaller in the region of the tungsten member in contact with the W-Pt-Cu alloy than in other regions. This is presumed to be because W was supplied from that region for the formation of the W-Pt-Cu alloy. And an improvement in strength can be expected in the region where the crystal structure of W is smaller.

[0094] (6) Elemental mapping In addition, in this study, HAADF-STEM (High Angle Annular Dark-Field Scanning Transmission Electron Microscopy) images (magnification 50,000x) were acquired from the specimens thinned using FIB-SEM. Elemental mapping images and EDX spectra were then obtained from these HAADF-STEM images. The results of the HAADF-STEM images and elemental mapping images are shown in Figure 19. Figure 20 shows the EDX spectrum of the entire W-Pt-Cu layer in the acquired HAADF-STEM image. Figure 21 shows the EDX spectrum of the W phase in W-Pt-Cu, and Figure 22 shows the EDX spectrum of the Pt-Cu phase.

[0095] First, as shown in Figure 20, the W-Pt-Cu layer as a whole mainly contained W, Cu, Pt, Mo, Fe, and O elements. Then, as shown in Figures 20 and 21, the W phase mainly contained W, Mo, Fe, and O elements. Of these, the Mo and Fe elements are thought to originate from impurities contained in the W plate. In the case of Mo, it is possible that it was detected from the sample folder. On the other hand, as shown in Figures 19 and 22, the Pt-Cu phase mainly contained Cu, Pt, and O elements. The O element, which was found in both the W and Pt-Cu phases, is thought to originate from oxygen deposited in the measurement environment or surface oxidation of the test piece. Furthermore, the image shown in Figure 19 clearly confirms that the W-Pt-Cu layer is a W-Pt-Cu alloy, which is a mixture of a W phase mainly composed of W and a Pt-Cu phase containing a Pt-Cu alloy.

[0096] Analysis of Figure 21 revealed that the W phase contained 84.57 atm% W atoms, 2.56 atm% Cu atoms, and 0.06 atm% Pt atoms. The W phase also contained 12.81 atm% molybdenum (Mo), an impurity, which is thought to be a detection of molybdenum present in the sample folder. On the other hand, analysis of Figure 22 revealed that the Pt-Cu phase contained 2.31 atm% W atoms, 78.13 atm% Cu atoms, and 15.59 atm% Pt atoms. The Pt-Cu phase also contained 3.97 atm% molybdenum (Mo), an impurity. This Mo is also thought to be a detection of molybdenum present in the sample folder.

[0097] C. Third Examination In this experiment, ten types of composites (samples 2-11) were prepared under different conditions than those of the second experiment described above. The preparation conditions for each sample and the analysis performed on each sample are described below.

[0098] (1) Sample 2 In Sample 2, a composite body was prepared by joining a tungsten member and a copper member under the same conditions as Sample 1, except that the Pt powder content in the Pt paste was reduced to 10 vol%. SEM observation and EDX analysis were performed on Sample 2 under the same conditions as the second test. The analysis results at a magnification of 5000x for Sample 2 are shown in Figure 23, and the analysis results at a magnification of 50000x are shown in Figure 24. In Figures 23 and 24, (a) is a cross-sectional SEM image, (b) is an elemental map of W, (c) is an elemental map of Cu, and (d) is an elemental map of Pt. Furthermore, SEM images (magnification of 50000x) of the W-Pt-Cu alloy formed in Sample 2 were acquired for 5 fields, and EDX analysis was performed on each field to measure the ratio (at%) of the number of atoms of W, Pt, and Cu. The measurement results are shown in Table 3 below.

[0099] [Table 3]

[0100] As shown in Figures 23 and 24, in Sample 2, a ternary diphase W-Pt-Cu alloy was formed at the joint between the tungsten and copper members, similar to Sample 1. Furthermore, calculated from the measurement results in each field of view shown in Table 2, the average ratio of W phase to Pt-Cu phase in the W-Pt-Cu layer of Sample 2 was 23.37:76.63. The ratio of Pt and Cu elements in the Pt-Cu phase was 7.07:92.93. From these results, it was found that the ratio of Pt to Cu in Sample 2 was smaller than in Sample 1. This is thought to be because a Pt paste with a lower Pt content was used compared to Sample 1.

[0101] Next, a line segment X1 with a length of 20 μm was drawn from the upper side (Pt-Cu alloy side) to the lower side (tungsten member side) of Figure 24(a), and line analysis was performed to examine the changes in the elemental concentrations of W, Pt, and Cu along this line segment X1. The results are shown in Figure 25. In Figure 25, the 0 μm position on the horizontal axis corresponds to the upper end of line segment X1, and the 20 μm position corresponds to the lower end of line segment X1. The vertical axis shows the characteristic X-ray intensity of each element. In Figure 25, graph (a) shows the analysis results for Pt, graph (b) shows the analysis results for W, and graph (c) shows the analysis results for Cu. As shown in Figure 25, in the region where the Pt-Cu alloy exists (upper side in Figure 23(a)), Pt and Cu are the main components, and W was hardly detected. In the region where the W-Pt-Cu alloy exists (the central part in Figure 23(a)), the elements W, Pt, and Cu were each confirmed. The tungsten component (the lower part in Figure 23(a)) was composed almost entirely of W, with a small amount of Pt present.

[0102] (2) Sample 3 In Sample 3, the tungsten and copper members were joined under the same conditions as in Sample 2, except that the firing temperature for the tungsten and copper members was changed to 800°C. SEM observation and EDX analysis were performed on Sample 3 under the same conditions as in the second test. The analysis results at a magnification of 5000x for Sample 3 are shown in Figure 26, the analysis results at a magnification of 50000x are shown in Figure 27, and the analysis results at a magnification of 200000x are shown in Figure 28. In Figures 26 to 28, (a) is a cross-sectional SEM image, (b) is an elemental map of W, (c) is an elemental map of Cu, and (d) is an elemental map of Pt. From these analysis results, it was confirmed that in Sample 3, the region where the W-Pt-Cu alloy exists is thin, and the microstructure in which the W phase and Pt-Cu phase are mixed is finer.

[0103] Furthermore, in Sample 3, quantitative analysis of the elemental counts of W, Pt, Cu, and O was performed based on EDX analysis of cross-sectional SEM images at a magnification of 200,000x (Figure 28). In this quantitative analysis, the number of W atoms in the W-Pt-Cu layer was 20.73%, the number of Pt atoms was 5.37 atm%, the number of Cu atoms was 69.11 atm%, and the number of O atoms was 4.79 atm%. In addition, the elemental analysis results showed no significant difference in the abundance ratios of W, Pt, and Cu elements in the W-Pt-Cu alloy between Sample 2 and Sample 3.

[0104] (3) Sample 4 In Sample 4, the tungsten and copper members were joined under the same conditions as in Sample 2, except that the binder removal treatment conditions after applying the Pt paste were changed to 160°C for 30 minutes. SEM observation and EDX analysis were performed on Sample 4 under the same conditions as in the second test. The analysis results at a magnification of 5000x for Sample 4 are shown in Figure 29, the analysis results at a magnification of 50000x for the Pt-Cu layer are shown in Figure 30, the analysis results at a magnification of 50000x for the Pt-W layer are shown in Figure 31, the analysis results at a magnification of 50000x for the W-Pt-Cu layer are shown in Figure 32, and the analysis results at a magnification of 50000x for the tungsten member are shown in Figure 33. In Figures 29 to 33, (a) is a cross-sectional SEM image, (b) is an elemental map of W, (c) is an elemental map of Cu, and (d) is an elemental map of Pt. Furthermore, in Sample 4, quantitative analysis of the number of W, Pt, and Cu elements was performed based on EDX analysis of the cross-sectional SEM images in Figures 29 to 33. The analysis results are shown in Table 4. In addition, for Sample 4, a line segment X2 with a length of 20 μm was drawn from the upper side (Pt-Cu alloy side) to the lower side (tungsten member side) of Figure 29(a), and the change in the concentration distribution of W, Pt, and Cu along this line was investigated. The results are shown in Figure 34. In Figure 34, the 0 μm position on the horizontal axis corresponds to the upper end of line segment X2, and the 20 μm position corresponds to the lower end of line segment X2. The vertical axis shows the characteristic X-ray intensity of each element. In Figure 34, (a) shows the analysis results for Pt, (b) shows the analysis results for W, and (c) shows the analysis results for Cu. As shown in Figure 34, in the region where the Pt-Cu alloy is present, the presence of Pt and Cu elements was confirmed, but the presence of W element was not confirmed. Furthermore, in the region where the W-Pt-Cu alloy was present, the elements W, Pt, and Cu were each detected. In the region containing tungsten material, most of it consisted of element W, but a small amount of element Pt was also present.

[0105] [Table 4]

[0106] In Sample 4, the W-Pt-Cu layer was thicker than in the other examples, and a layer mainly composed of Pt-W was present on top of it. It is presumed that the formation of such a thick W-Pt-Cu layer was due to a reduction in the temperature of the debindering process, which resulted in less tungsten oxide formation, allowing the formation of the Pt-W alloy, a precursor of W-Pt-Cu, to be unimpeded and thus form a thick layer. Furthermore, as shown in Figure 29, it was found that in Sample 4, a Pt-W layer containing Pt and W was formed at the boundary between the W-Pt-Cu layer and the Pt-Cu layer. This Pt-W layer was partially interrupted, and the W-Pt-Cu layer was present in the interrupted portion. From this, it is inferred that in this sample, when the W-Pt-Cu alloy was formed, the Pt-W alloy and Cu mixed through the interrupted portion of the Pt-W layer.

[0107] Furthermore, in Sample 4, Sample 1 was thinned using FIB-SEM, and backscattered electron images were obtained in a different field of view than that shown in Figure 29(a) above, and various analyses were performed. First, Figure 35(a) is a backscattered electron image of Sample 4 (5000x magnification), (b) is a magnified view of region α in (a) (20000x magnification), and (c) is a magnified view of region β in (a) (20000x magnification). As shown in Figure 35, in Sample 4, a W-Pt-Cu layer was formed on a W plate, a Pt-W layer was formed on top of that, and a Pt-Cu layer was formed on top of that. In Sample 4, elemental mapping images based on EDX analysis were obtained in each of regions α and β in Figure 35(a). The results of the elemental mapping image in region α are shown in Figure 36, and the results of the elemental mapping image in region β are shown in Figure 37. First, as shown in Figure 36, it was confirmed that in the Pt-W layer within region α, trace amounts of Pt-Cu crystal particles were present between Pt-W crystal particles with a particle diameter of approximately 100-500 nm. The area ratio of Pt-W crystal particles to Pt-Cu crystal particles in this Pt-W layer was 98.5:1.5. Furthermore, the W phase present at the interface between the W-Pt-Cu layer and the Pt-W layer was formed almost entirely of tungsten. Also, as shown in Figure 37, the area ratio of the Pt-Cu phase to the W phase in the W-Pt-Cu layer was 52.9:47.1.

[0108] Next, in Sample 4, HAADF-STEM images and elemental mapping images of those HAADF-STEM images were also acquired. Figure 38 shows the results of the HAADF-STEM image and elemental mapping image of Sample 4. Figure 39 is a graph showing the concentration distribution of Pt, Cu, and W along line segment X3 in Figure 38. As shown in Figures 38 and 39, Sample 4 consisted of a W plate mainly composed of W, a W-Pt-Cu layer having a W phase and a Pt-Cu phase, a Pt-W layer formed of a Pt-W alloy, and a Pt-Cu layer formed of a Pt-Cu alloy. The relative abundance of the metallic elements in each layer was as shown in Table 5.

[0109] [Table 5]

[0110] Furthermore, Figure 40 shows the results of HAADF-STEM images and elemental mapping images at the interface between the W plate of sample 4, the W phase of the W-Pt-Cu layer, and the Pt-Cu phase of the W-Pt-Cu layer. Also, Figure 41 is a graph showing the concentration distribution of Pt, Cu, and W along line segment X4 in Figure 40, and Figure 42 is a graph showing the concentration distribution of O and Fe along line segment X4. First, as shown in Figures 40 and 41, there were almost no Pt or Cu elements in the W plate, and almost no W elements in the Pt-Cu phase of the W-Pt-Cu layer. From this, it can be understood that there was almost no diffusion of metal elements at the interface between the Pt-Cu phase of the W-Pt-Cu layer and the W plate. In addition, as shown in Figures 40 and 42, the presence of a small amount of iron (Fe) was confirmed in the W plate. The presence of oxygen (O) is presumed to be due to measurement noise. Furthermore, these Fe and O elements were present in all regions, and no clear segregation was observed at the interface between the Pt-Cu phase of the W-Pt-Cu layer and the W plate.

[0111] Furthermore, in Sample 4, electron diffraction was performed in each region from region α to region δ in Figure 38. The results are shown in Figure 43. Figure 43(a) is an image showing the results of electron diffraction in region α (W plate). From these electron diffraction results, the element present in region α (W plate) was identified as W. Next, Figure 43(b) is an image showing the results of electron diffraction in region β (W-Pt-Cu layer). From these electron diffraction results, the W phase and Pt-Cu phase were confirmed in region β (W-Pt-Cu layer). Furthermore, it was found that at least Cu3Pt is present in the Pt-Cu phase in the W-Pt-Cu layer. Finally, Figure 43(c) is an image showing the results of electron diffraction in region γ (Pt-W layer). In this Pt-W layer, in addition to the Pt-W alloy, a Pt-Cu alloy was also confirmed. Furthermore, the Pt-W layer contained at least Pt2W as a Pt-W alloy and at least Cu3Pt as a Pt-Cu alloy. Figure 43(d) is an image showing the electron diffraction results in region δ (Pt-Cu layer). This Pt-Cu layer contained at least Cu3Pt as a Pt-Cu alloy.

[0112] Next, as shown in Figure 40 above, HAADF-STEM images and elemental mapping images were obtained at the interface between the W plate and the W-Pt-Cu layer in Sample 4. In addition, HAADF-STEM images and elemental mapping images were obtained for each layer of the W plate, Pt-W layer, and Pt-Cu layer in Sample 4. The results are shown in Figures 44 to 46. As shown in Figures 40 and 44 to 46, a Pt-Cu phase containing Pt and Cu was confirmed in each region of the W plate, W-Pt-Cu layer, Pt-W layer, and Pt-Cu layer in Sample 4. The EDX spectra of the Pt-Cu phase in each of these regions are shown in Figures 47 to 50, and the elemental ratios calculated based on these EDX spectra are shown in Table 6. As shown in Figures 47 to 50 and Table 6, there were no significant differences in the elemental ratios of the Pt-Cu phase present in each layer.

[0113] [Table 6]

[0114] Based on the above analysis, a W-Pt-Cu alloy was formed between the Pt-W layer and the W plate in sample 4. From this, it is thought that a Pt-W alloy was generated by applying Pt paste to the W plate and heat treatment, and then a Cu-containing component entered the Pt-W alloy, causing Pt in the Pt-W alloy to move (diffuse) into Cu, thereby generating a W-Pt-Cu alloy. Furthermore, as shown in Figure 44, Cu also entered the W plate in sample 4. This also suggests a generation process in which Cu enters the Pt-W alloy side.

[0115] (4) Sample 5 In Sample 5, the tungsten and copper members were joined under the same conditions as in Sample 2, except that the binder removal treatment conditions after applying the Pt paste were changed to 450°C for 30 minutes. SEM observation and EDX analysis were performed on Sample 5 under the same conditions as in the second test. The analysis results at a magnification of 5000x for Sample 5 are shown in Figure 51, and the analysis results at a magnification of 50000x for the W-Pt-Cu alloy are shown in Figure 52. In Figures 51 and 52, (a) is a cross-sectional SEM image, (b) is an elemental map of W, (c) is an elemental map of Cu, and (d) is an elemental map of Pt. As a result of these analyses, it was confirmed that in Sample 5, the W-Pt-Cu layer was thinner than in Samples 1, 2, and 4, and the distribution of the W-Pt-Cu alloy on the W plate was mottled. This is presumed to be because the high temperature of the binder removal process caused tungsten oxide to form on the surface of the W plate, and this tungsten oxide inhibited the reaction between the W material and Pt, thereby inhibiting the formation of the Pt-W alloy. Furthermore, in sample 5, a quantitative analysis of the number of W, Pt, and Cu elements in the W-Pt-Cu alloy was performed based on the EDX analysis in Figure 52. As a result of this quantitative analysis, the number of W atoms in the W-Pt-Cu layer was 31.06%, the number of Pt atoms was 2.03 atm%, and the number of Cu atoms was 66.91 atm%. As a result of this elemental analysis, it was found that the abundance of Pt elements in the W-Pt-Cu alloy of sample 5 was lower than that of samples 2-4.

[0116] (5) Sample 6 In Sample 6, a Cu paste was used as the Cu source instead of a plate-shaped copper member. Specifically, a Pt paste with the same composition as Sample 2 was applied to the surface of a tungsten member of the same dimensions as Sample 1. Then, drying and binder removal treatments were performed under the same conditions as Sample 4. After that, Cu paste was applied to the Pt paste surface, followed by drying (120°C, 30 minutes) and heat treatment. The heat treatment was set to the same conditions as Sample 1. The Cu paste used in this sample was a mixture of Cu powder with an average particle size of 0.5 μm, glass powder, ethyl cellulose resin, a dispersant, and a solvent. SEM observation and EDX analysis were performed on Sample 6 under the same conditions as the second test. The analysis results for Sample 6 at a magnification of 5000x are shown in Figure 53, and the analysis results for the W-Pt-Cu alloy at a magnification of 50000x are shown in Figure 54. In Figures 53 and 54, (a) is a cross-sectional SEM image, (b) is an elemental map of W, (c) is an elemental map of Cu, and (d) is an elemental map of Pt. As a result of this analysis, the formation of a W-Pt-Cu alloy was confirmed in sample 6, just as in the other samples. From this, it was found that Cu paste can be used as the Cu source even in an embodiment in which the W source, Pt source, and Cu source are heat-treated simultaneously. Furthermore, in sample 6, quantitative analysis of the number of W, Pt, and Cu elements in the W-Pt-Cu alloy was performed based on the EDX analysis in Figure 54. As a result of this quantitative analysis, the number of W atoms in the W-Pt-Cu layer of sample 6 was 40.16%, the number of Pt atoms was 2.27 atm%, and the number of Cu atoms was 57.57 atm%.

[0117] (6) Sample 7 In Sample 7, we investigated whether a W-Pt-Cu alloy could be formed when an intermediate metal component (Pt film) was interposed between the W-Pt alloy and the Cu source. Specifically, a thick layer of Pt paste with the same composition as Sample 2 was applied to the surface of a tungsten component of the same dimensions as Sample 1. After drying at 120°C for 30 minutes, binder removal was performed by heat treatment in air (heating rate: 10°C / min, maximum temperature: 160°C, heating time: 0.5h). Subsequently, firing treatment was carried out in an N2-H2 (3%) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, firing time: 2 hours). The sample was then cooled to room temperature, and it was confirmed that a Pt firing film had been formed on the surface of the W plate. Next, the same Cu paste as in Sample 6 was applied to the surface of this Pt firing film and dried at 120°C for 30 minutes. Then, the samples were subjected to a firing process in an N2-H2 (3%) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, firing time: 2 hours). After the samples were cooled to room temperature, the cross-sections were polished by ion milling, and then observed by SEM and analyzed by EDX.

[0118] Figure 55 shows the analysis results of sample 7 at a magnification of 5000x. Figures 56 to 59 show the analysis results of each part of sample 7 at a magnification of 50000x: the Pt-W layer, the W-Pt-Cu layer, the W plate, and the interface between the W plate and the W-Pt-Cu layer. In Figures 55 to 59, (a) is a cross-sectional SEM image, (b) is the elemental map of W, (c) is the elemental map of Cu, and (d) is the elemental map of Pt. As shown in Figures 55 to 59, it was confirmed that a W-Pt-Cu alloy was formed in sample 7, just as in samples 2 to 6. From this, it was found that direct contact between the W-Pt alloy and the Cu source is not necessary to form a W-Pt-Cu alloy, and an intermediate metal component (Pt film) may be interposed between the W-Pt alloy and the Cu source.

[0119] Furthermore, in Sample 7, quantitative analysis of the number of W, Pt, and Cu elements in the W-Pt-Cu alloy was performed based on the EDX analysis shown in Figures 55 to 59. Table 7 shows the results of the analysis at a magnification of 5000x (Figure 55) and the quantitative analysis of the number of elements in each part: the Pt-W layer (Figure 56), the W-Pt-Cu layer (Figure 57), the W plate (Figure 58), and the interface between the W plate and the W-Pt-Cu layer (Figure 59).

[0120] [Table 7]

[0121] (7) Sample 8 In Sample 8, the shapes of the Pt-W alloy produced in the Pt-W alloy production process and the W-Pt-Cu alloy produced in the W-Pt-Cu alloy production process were compared. Specifically, a thin layer of Pt paste with the same composition as Sample 2 was applied to the surface of a W plate of the same dimensions as Sample 1. After drying at 120°C for 30 minutes, the binder was removed by heat treatment in air (heating rate: 10°C / min, maximum temperature: 160°C, heating time: 0.5h). Subsequently, firing treatment was performed in an N2-H2 (3%) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, firing time: 2 hours). The sample was then cooled to room temperature, and it was confirmed that a W-Pt alloy had been formed on the surface of the W plate. The surface of the W-Pt alloy produced in this sample was rough with fine irregularities. Next, in this sample, a coated area with Cu paste (Cu source) applied to the surface of a W-Pt alloy and an uncoated area without Cu paste were created. The same Cu paste used in Sample 6 was used. The Cu paste in the coated area was dried at 120°C for 30 minutes, and then fired in an N2-H2 (3%) atmosphere (heating temperature: 4°C / min, maximum temperature: 1000°C, firing time: 2 hours). After the sample was cooled to room temperature, the cross-section was polished by ion milling, and SEM observation and EDX analysis were performed.

[0122] Figures 60 and 61 show the analysis results for the uncoated region of Sample 8. On the other hand, Figures 62 to 65 show the analysis results for the coated region. First, as shown in Figure 60, a W-Pt alloy with fine irregularities on its surface was formed on the surface of the W plate in the uncoated region. On the other hand, as shown in Figures 62 to 65, a W-Pt-Cu alloy was formed between the W plate and the Pt-Cu layer in the coated region. Furthermore, the W-Pt-Cu alloy in Sample 8 had fine irregularities on its surface (interface on the Pt-Cu layer side), similar to the W-Pt alloy in the uncoated region. From this, it was found that the shape of the Pt-W alloy produced in the Pt-W alloy production process is reflected in the shape of the W-Pt-Cu alloy after the W-Pt-Cu alloy production process.

[0123] (8) Sample 9 In Sample 9, Cu paste was applied to the surface of a plate-shaped tungsten component and then dried and fired. Specifically, Cu paste with the same composition as Sample 6 was applied to the surface of a tungsten component of the same dimensions as Sample 1. After drying the Cu paste by drying at 120°C for 30 minutes, it was heated in air at 400°C for 1 hour. Subsequently, a firing process was performed with a firing rate of 5°C / min, a maximum firing temperature of 1000°C, and a firing time of 30 minutes. SEM observation and EDX analysis were performed on Sample 9 under the same conditions as in the second test. The analysis results for Sample 9 at a magnification of 250x are shown in Figure 66, the analysis results at a magnification of 1000x are shown in Figure 67, the analysis results at a magnification of 5000x are shown in Figure 68, and the analysis results at a magnification of 50000x are shown in Figure 69. In Figures 66-69, (a) is a cross-sectional SEM image, (b) is an elemental map of O (oxygen), (c) is an elemental map of Cu, and (d) is an elemental map of W. These analyses also showed that no alloy material containing both W and Cu was formed. In other words, it was found that even when Cu and W are brought into contact and heat-treated in the absence of Pt (a state in which no W-Pt alloy is formed), an alloy material containing both W and Cu is not formed.

[0124] (9) Sample 10 In Sample 10, Pt paste was applied to the surface of a plate-shaped tungsten component and then dried and fired. Specifically, Pt paste with the same composition as Sample 1 was applied to the surface of a tungsten component of the same dimensions as Sample 1. The Pt paste was then dried at 120°C for 30 minutes, followed by a heat treatment in air at 160°C for 0.5 hours. After that, a firing treatment was performed with a firing rate of 3°C / min, a maximum firing temperature of 1300°C, and a firing time of 10 minutes. SEM observation and EDX analysis were performed on Sample 10 under the same conditions as the second test. The analysis results of Sample 10 at a magnification of 5000x are shown in Figure 70. In Figure 70, (a) is a cross-sectional SEM image, (c) is the elemental map of W, and (d) is the elemental map of Pt. As a result of these analyses, it was confirmed that an alloy containing Pt and W (Pt-W alloy) is produced by heating with a Pt source and a W source in contact, as in this sample. However, in this sample, two-phase alloys like those in samples 1-8 were not formed.

[0125] (10) Sample 11 In Sample 11, a Pt-Cu paste was applied to the surface of a plate-shaped tungsten component and then dried and fired. Specifically, a Pt-Cu paste, in which Pt particles and Cu particles were uniformly dispersed, was applied to the surface of a tungsten component of the same dimensions as Sample 1. After drying the paste by drying it at 120°C for 30 minutes, a first heat treatment was performed in air at 160°C for 0.5 hours, followed by a second heat treatment in N2 gas containing 3% H2 gas, with a heating rate of 10°C / min, a maximum heating temperature of 400°C, and a heating time of 1 hour. Finally, a heat treatment was performed with a heating rate of 5°C / min, a maximum firing temperature of 1000°C, and a firing time of 30 minutes. SEM observation was performed on Sample 11 under the same conditions as the second test. The analysis results for Sample 11 at a magnification of 5000x are shown in Figure 71, and the analysis results at a magnification of 50000x are shown in Figure 72. These analyses revealed that when a Pt source and a Cu source were mixed, as in this sample, a W-Pt-Cu alloy was not formed despite the presence of a W source, a Pt source, and a Cu source. Only unreacted W material and a Pt-Cu alloy formed on the surface of the W material were observed. Furthermore, the W material and the Pt-Cu alloy were not properly bonded. The reason for this result is presumed to be as follows: In this sample, the reaction between the mixed Pt source and Cu source occurred preferentially, and a Pt-W alloy was not formed. The Pt-Cu alloy formed by the reaction of the Pt source and Cu source had low reactivity with the W material, so a W-Pt-Cu alloy like that in samples 1-6 was not formed. From this, it was found that in order to form a W-Pt-Cu alloy, it is necessary to form a Pt-W alloy as a precursor and then transfer Pt from that Pt-W alloy to Cu.

[0126] D. The fourth examination In this experiment, we manufactured a W-Pt-Cu alloy containing a Pt-Cu phase that includes a third metallic element in addition to Cu and Pt. The specific manufacturing procedure is described below.

[0127] First, a Pt paste was applied to a W plate measuring 0.3 mm thick x 7.5 mm x 7.5 mm. The Pt paste was prepared by kneading Pt powder with an average particle size of 0.5 μm, a binder (ethyl cellulose resin), a dispersant, and a solvent (2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutyrate). The W plate coated with the Pt paste was then dried (120°C, 30 minutes), followed by a binder removal treatment (in air, 160°C, 0.5 hours). Finally, a heat treatment was performed in a reducing atmosphere (N2-H2 (3%) atmosphere) to form a Pt-W alloy (Pt2W) on the surface of the W plate. During the heat treatment, the heating rate was set to 4°C / min, and the temperature was held for 2 hours after reaching the maximum temperature (1000°C).

[0128] Next, Au paste was applied to the Pt-W alloy surface of the W plate, followed by a drying treatment (120°C, 30 minutes). The Au paste was prepared by kneading Au powder with an average particle size of 0.5 μm, a binder (ethyl cellulose), a dispersant, and a solvent (terpineol). Then, Cu paste was applied on top of the dried Au paste, followed by a drying treatment (120°C, 30 minutes). The same Cu paste used was used for the preparation of sample A-2 for analysis in the first test. Sample 12 was then prepared by heat treatment in a reducing atmosphere (N2-H2 (3%) atmosphere). During the heat treatment, the heating rate was set to 4°C / min, and the temperature was held for 2 hours after reaching the maximum temperature (1000°C).

[0129] The cross-section of the prepared sample 12 was CP polished and SEM-EDX analysis was performed. The results are shown in Figures 73 and 74. The magnification in Figure 73 is 5000x, and the magnification in Figure 74 is 50000x. In Figures 73 and 74, (a) is the cross-sectional SEM image, (b) is the elemental map of W, (c) is the elemental map of Cu, (d) is the elemental map of Pt, and (e) is the elemental map of Au. The atomic concentration of Cu measured by SEM-EDX analysis was 65.64%, the atomic concentration of W was 24.50%, the atomic concentration of Pt was 1.23%, and the atomic concentration of Au was 8.62%.

[0130] Analysis revealed that a W-Pt-Cu alloy, consisting of a mixture of W phase and Pt-Cu phase, was also formed in sample 12. However, it was found that the Pt-Cu phase of the W-Pt-Cu alloy produced in this sample contained Au in addition to Pt and Cu (see Figures 73(e) and 74(e)). From these results, it was found that, as in this experiment, when a third element is added to the Cu source, the third element diffuses into the Pt-Cu phase along with Cu and Pt.

[0131] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. [Explanation of Symbols]

[0132] 10 Alloy material 12 W phase 14 Pt-Cu phase 20 First Member 30 Second Member 100 zygote

Claims

1. A W-Pt-Cu alloy for joining, comprising three elements: tungsten (W), platinum (Pt), copper (Cu), and unavoidable impurities, The W phase, which mainly consists of tungsten (W), and the Pt-Cu phase, which has platinum (Pt) and copper (Cu), are mixed together. Based on SEM-EDX, the number of tungsten atoms in the W phase is 75 atm% or more. Based on the aforementioned SEM-EDX, the number of platinum atoms in the Pt-Cu phase is 0.1 atm% or more and 25 atm% or less. In SEM observation, area 0.001 μm ２ ~1 μm ２ The W phase is present at 0.2 locations / μm ２ It has a W-phase-existing region at the above density, The W-phase region exists in a width and depth direction of 10 μm or more in a plan view. A W-Pt-Cu alloy for joining, characterized by the following features.

2. The W phase contains at least one selected from the group consisting of Mo, Fe, Co, Ni, Au, and Th as the unavoidable impurity. The W-Pt-Cu alloy for joining according to claim 1, wherein the Pt-Cu phase contains at least one selected from the group consisting of Mo, Fe, Pd, Ir, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, and Th as the unavoidable impurity.

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