Metal joint

Abstract

To provide a novel technique allowing for improving the strength of joining between a W-based member and a Cu-based member 30.SOLUTION: The metal joint 100 disclosed herein at least comprises a W-based member 10 containing tungsten (W) and a Cu-based member 30 containing copper (Cu). The metal joint 100 disclosed herein is formed, on a surface of the W-based member 10, with projections intruding in an opposed layer (intermediate layer 20) to the W-based member 10, thereby making it possible to firmly join the W-based member 10 and the opposed layer (intermediate layer 20) together through anchor effects. The intermediate layer 20 can be suitably joined to the Cu-based member 30 because of a containment of a Cu element. According to the metal joint disclosed herein, the W-based member 10 and the Cu-based member 30 can be firmly joined together through the intermediate layer 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a metal bonded body. Specifically, it relates to a metal bonded body including a tungsten-based member and a copper-based member.

Background Art

[0002] A tungsten-based member (hereinafter also referred to as a "W-based member") containing tungsten (W) has characteristics of a high melting point and a low coefficient of thermal expansion, and is excellent in reliability in a high-temperature environment. For this reason, W-based members are used for ultra-high temperature components exposed to high-temperature environments such as diverters, accelerators, plasma discharge devices, high-temperature furnaces, and thin film forming devices. On the other hand, tungsten is a rare and expensive metal, and is difficult to process. Therefore, it is often used in a state joined to a member mainly composed of a metal other than tungsten (hereinafter also referred to as a "dissimilar metal member"). For example, from the viewpoints of material cost and heat dissipation (thermal conductivity), as an example of a dissimilar metal member to be joined, a copper-based member containing copper (Cu) (hereinafter also referred to as a "Cu-based member") can be cited.

[0003] In the production of this type of metal bonded body, for example, the W-based member and the Cu-based member are directly joined using diffusion bonding (Diffusion Bonding Method). In this diffusion bonding, heating and pressure are simultaneously applied while the W-based member and the Cu-based member are in close contact. As a result, a W-Cu diffusion layer in which W elements and Cu elements mutually diffuse is formed between the W-based member and the Cu-based member, and the W-based member and the Cu-based member are joined through the W-Cu diffusion layer. An example of such diffusion bonding is disclosed in Non-Patent Document 1. In the diffusion bonding described in Non-Patent Document 1, the temperature is set to 980°C and the pressure is set to 106 MPa. And in Non-Patent Document 1, it is reported that a W-Cu diffusion layer with a thickness of about 22 nm is formed between the W-based member and the Cu-based member by diffusion bonding under the above conditions.

Prior Art Documents

Non-Patent Documents

[0004] [Non-Patent Document 1] J. Zhang et al., Material and design 137(2018)473-480 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Incidentally, in recent years, there has been a growing demand for improved durability of ultra-high temperature components, and there is a need for technology that can improve the bonding strength between W-based and Cu-based materials. The present invention has been made in response to this demand, and its main objective is to provide a novel technology that can improve the bonding strength between W-based and Cu-based materials. [Means for solving the problem]

[0006] To achieve the above objectives, the technology disclosed herein provides a metal joint having the following configuration.

[0007] The metal joint disclosed herein comprises at least a tungsten-based member containing tungsten (W) and a copper-based member containing copper (Cu). In the metal joint disclosed herein, a projection is formed on the surface of the tungsten-based member that penetrates into the opposing layer of the tungsten-based member.

[0008] In the metal joint described above, protrusions are formed on the surface of the W-type member that penetrate into the opposing layer of the W-type member. As a result, an anchoring effect is exerted at the interface between the W-type member and the opposing layer, allowing the W-type member and the Cu-type member to be firmly joined.

[0009] In one preferred embodiment of the metal joint disclosed herein, the average width a of the protrusions is 0.01 μm or more and 1 μm or less. This allows for a more appropriate anchoring effect at the interface between the W-type member and the opposing layer.

[0010] In one preferred embodiment of the metal joint disclosed herein, the average aspect ratio (b / a) of the protrusions is 1 or greater. This allows for a more appropriate anchoring effect at the interface between the W-type member and the opposing layer.

[0011] In one preferred embodiment of the metal joint disclosed herein, the average length b of the protrusions is 0.05 μm or more and 5 μm or less. This allows for a more appropriate anchoring effect at the interface between the W-type member and the opposing layer.

[0012] In one preferred embodiment of the metal joint disclosed herein, the projections are dendritic projections that branch out from the surface of the tungsten-based member toward the opposing layer. This allows for a more appropriate anchoring effect at the interface between the W-based member and the opposing layer. Preferably, the average number of branches of these dendritic projections is between 1 and 5.

[0013] In one preferred embodiment of the metal joint disclosed herein, the tungsten-based member is selected from the group consisting of tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, and tungsten composite materials. The technology disclosed herein is particularly suitable for these W-based members. An example of the tungsten composite material is a tungsten composite material containing at least one element selected from the group consisting of copper (Cu), cobalt (Co), nickel (Ni), and molybdenum (Mo).

[0014] In one preferred embodiment of the metal joint disclosed herein, a copper-based member is joined to the surface of a tungsten-based member, with projections penetrating the copper-based member. In the art disclosed herein, projections of the W member can, for example, directly penetrate a Cu-based member. According to this embodiment, the strength of the direct joint between the W member and the Cu member can be improved by an anchoring effect.

[0015] In one preferred embodiment of the metal joint disclosed herein, an intermediate layer containing platinum (Pt) and copper (Cu) is formed between a tungsten-based member and a copper-based member, with protrusions penetrating the intermediate layer. In the technology disclosed herein, an intermediate layer can also be formed between a W member and a Cu-based member, and the protrusions can penetrate the intermediate layer. In this embodiment, the W member and the intermediate layer can be firmly joined by an anchoring effect. Furthermore, since this intermediate layer contains Cu, the main component of the Cu-based member, it can be firmly joined to the Cu-based member. Therefore, according to this embodiment, a metal joint in which the W member and the Cu-based member are firmly joined via the intermediate layer can be obtained. In addition, in this embodiment, the difference in thermal expansion coefficients between the W member and the Cu-based member can be mitigated in the intermediate layer, thus contributing to the stabilization of the joint strength between the W member and the Cu-based member.

[0016] In the embodiment in which the above intermediate layer is formed, the intermediate layer contains a W-Pt-Cu alloy in which a W phase mainly composed of tungsten (W) and a Pt-Cu phase containing platinum (Pt) and copper (Cu) are mixed. This allows for more appropriate joining of the W-based member and the Cu-based member.

[0017] Furthermore, it is preferable that the above-mentioned W-Pt-Cu alloy is composed of multiple W phases within a matrix consisting of Pt-Cu phases. By forming an intermediate layer with a structure in which W phases and Pt-Cu phases are mixed in this way, W-based members and Cu-based members can be joined more appropriately.

[0018] Furthermore, as another aspect of the technology disclosed herein, a joining method for joining a tungsten-based member and a copper-based member is provided. In this joining method, a Pt-W alloy containing platinum (Pt) and tungsten (W) is formed on the surface of the tungsten-based member, and while a Cu source is in contact with the Pt-W alloy, the platinum (Pt) of the Pt-W alloy is moved to the Cu source, thereby forming protrusions on the surface of the tungsten-based member that penetrate into the opposing layer of the tungsten-based member. By forming protrusions on the surface of the W-based member in this way, an anchoring effect is exerted at the interface between the W-based member and the opposing layer, so that a metal joint in which the W-based member and the Cu-based member are firmly joined can be manufactured.

[0019] In one preferred embodiment of the joining method disclosed herein, a copper-based member is joined to the surface of a tungsten-based member, and the protrusions are made to penetrate the copper-based member. According to the joining method disclosed herein, the protrusions of the W member can be made to penetrate the Cu member directly. This makes it possible to manufacture a metal joint in which the W member and the Cu member are directly joined by an anchoring effect.

[0020] In one preferred embodiment of the joining method disclosed herein, an intermediate layer containing platinum (Pt) and copper (Cu) is formed between a tungsten-based member and a copper-based member, and the protrusions are allowed to penetrate the intermediate layer. According to the joining method disclosed herein, the protrusions of the W member can also be allowed to penetrate the intermediate layer between the W member and the Cu-based member. This allows the W member and the intermediate layer to be firmly joined by an anchoring effect, and the W member and the Cu-based member to be firmly joined through the intermediate layer.

[0021] In one preferred embodiment of the joining method disclosed herein, heat treatment is performed with a platinum (Pt) source interposed between the tungsten-based member and the copper-based member. In another preferred embodiment of the joining method disclosed herein, pressurization is performed with a platinum (Pt) source interposed between the tungsten-based member and the copper-based member. By performing these treatments, the formation of a Pt-W alloy and the migration of Pt from the Pt-W alloy to the Cu-based member can be achieved, thereby making it easier to join the W-based member and the Cu-based member.

Brief Description of the Drawings

[0022] [Figure 1] It is a cross-sectional view schematically showing a metal bonded body according to a first embodiment. [Figure 2] It is a cross-sectional view schematically showing an example of a Pt-W generation process in a method for manufacturing a metal bonded body according to a first embodiment. [Figure 3] It is a cross-sectional view schematically showing an example of a Pt-Cu generation process in a method for manufacturing a metal bonded body according to a first embodiment. [Figure 4] It is a cross-sectional view schematically showing a metal bonded body according to a second embodiment. [Figure 5] It is a cross-sectional view schematically showing a metal bonded body according to a third embodiment. [Figure 6] (a) is a cross-sectional SEM image (250 times magnification) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 7] (a) is a cross-sectional SEM image (1000 times magnification) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 8] (a) is a cross-sectional SEM image (3000 times magnification) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 9] (a) is a cross-sectional SEM image (10000 times magnification) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 10] (a) is a cross-sectional SEM image (50000 times magnification) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 11] It is a SEM image when Example 1 is processed by FIB. (a) is an image showing the boundary between the Cu-based member and the W-based member, and (b) and (c) are images obtained by further magnifying the boundary portion. [Figure 12] It is a diagram showing the results of a HAADF-STEM image and an elemental mapping image of Example 1. [Figure 13] Figure 12 shows a magnified view of the W-Pt-Cu region in the HAADF-STEM image. [Figure 14] This is the EDX spectrum in region A (W phase) in Figure 13. [Figure 15] This is the EDX spectrum in region B (Pt-Cu phase) in Figure 13. [Figure 16] This is a cross-sectional SEM image showing the dimensions of the protrusions of the W-type member in Example 1. [Figure 17] (a) is a cross-sectional SEM image (5000x magnification) of Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 18] (a) is a cross-sectional SEM image (50,000x magnification) of the Pt-Cu region in Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 19] (a) is a cross-sectional SEM image (50,000x magnification) of the Pt-W region in Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 20] (a) is a cross-sectional SEM image (50,000x magnification) of the W-Pt-Cu region in Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 21] (a) is a cross-sectional SEM image (50,000x magnification) of the W-based member of Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 22] This graph shows the concentration distributions of W, Pt, and Cu along line segment X1 in Figure 17(a). 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 23] This figure shows the backscattered electron image (1000x magnification) of Example 2. [Figure 24] (a) is a backscattered electron image of Example 2 (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 25] (a) is a cross-sectional SEM image (20,000x magnification) of region α in Example 2, and (b) to (d) are elemental maps of Cu, Pt, and W based on EDX analysis, respectively. [Figure 26] (a) is a cross-sectional SEM image (20,000x magnification) of region β in Example 2, and (b) to (d) are elemental maps of Cu, Pt, and W based on EDX analysis, respectively. [Figure 27] This figure shows the results of the HAADF-STEM images and elemental mapping images from Example 2. [Figure 28] This graph shows the concentration distributions of Pt, Cu, and W along line segment X2 in Figure 27. [Figure 29] This figure shows the results of HAADF-STEM images and elemental mapping images at the interface between the W-system member of Example 2, the W phase of the W-Pt-Cu region, and the Pt-Cu phase of the W-Pt-Cu region. [Figure 30] This graph shows the concentration distribution of Pt, Cu, and W along line segment X3 in Figure 29. [Figure 31] This graph shows the concentration distribution of O and Fe along line segment X3 in Figure 29. [Figure 32] (a) is an image showing the electron diffraction results in region α in Figure 27(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 33] This figure shows the results of HAADF-STEM images and elemental mapping images for the W-type member of Example 2. [Figure 34] This figure shows the results of HAADF-STEM images and elemental mapping images in the Pt-W region of Example 2. [Figure 35] This figure shows the results of HAADF-STEM images and elemental mapping images in the Pt-Cu region of Example 2. [Figure 36] Figure 33 shows the EDX spectrum of the Pt-Cu phase. [Figure 37]Figure 29 shows the EDX spectrum of the Pt-Cu phase. [Figure 38] Figure 34 shows the EDX spectrum of the Pt-Cu phase. [Figure 39] Figure 35 shows the EDX spectrum of the Pt-Cu phase. [Figure 40] This is a cross-sectional SEM image showing the dimensions of the protrusions of the W-type member in Example 2. [Figure 41] (a) is a cross-sectional SEM image (5000x magnification) of Example 3, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 42] (a) is a cross-sectional SEM image (50,000x magnification) of Example 3, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 43] This is a cross-sectional SEM image showing the dimensions of the protrusions of the W-type member in Example 3. [Figure 44] (a) is a cross-sectional SEM image (5000x magnification) of Example 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 45] (a) is a cross-sectional SEM image (50,000x magnification) of the Pt-W region in Example 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 46] (a) is a cross-sectional SEM image (50,000x magnification) of the W-Pt-Cu region in Example 4, and (b) to (d) are elemental maps of Pt, Cu, and W based on EDX analysis, respectively. [Figure 47] (a) is a cross-sectional SEM image (50,000x magnification) of the W-type member of Example 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 48] (a) is a cross-sectional SEM image (50,000x magnification) of the interface between the W-based member and the W-Pt-Cu region of Example 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 49] This is a cross-sectional SEM image showing the dimensions of the protrusions of the W-type member in Example 4. [Figure 50] (a) is a cross-sectional SEM image (5000x magnification) of the uncoated Cu area of ​​Example 5, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 51] (a) is a cross-sectional SEM image (50,000x magnification) of the uncoated Cu area of ​​Example 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 (5000x magnification) of the Cu coated area of ​​Example 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 (50,000x magnification) of the W-Pt-Cu region formed in the Cu coated area of ​​Example 5, 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 the W-Pt-Cu region formed in the Cu coated area of ​​Example 5, 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 (50,000x magnification) of the boundary between the intermediate layer (W-Pt-Cu region) formed in the Cu coated portion of Example 5 and the W plate, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 56] This is a cross-sectional SEM image showing the dimensions of the protrusions of the W-type member in Example 5. [Figure 57] (a) is a cross-sectional SEM image (5000x magnification) of Example 6, and (b) to (e) are elemental maps of W, Cu, Pt, and Au based on EDX analysis, respectively. [Figure 58] (a) is a cross-sectional SEM image (50,000x magnification) of the boundary between the intermediate layer (W-Pt-Cu region) and the W plate in Example 6, and (b) to (e) are elemental maps of W, Cu, Pt, and Au based on EDX analysis, respectively. [Figure 59] This is a cross-sectional SEM image showing the dimensions of the protrusions of the W-type member in Example 6. [Figure 60] (a) is a cross-sectional SEM image (5000x magnification) of Example 7, 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 Pt-Cu region in Example 7, 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 (50,000x magnification) of the first W-Pt-Cu region of Example 7, 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 Pt-W layer in Example 7, 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 boundary between the intermediate layer (second W-Pt-Cu region) and the W-based member of Example 7, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. [Figure 65] This graph shows the concentration distributions of Pt, Cu, and W along line segment X4 in Figure 60. [Figure 66] This is a cross-sectional SEM image showing the dimensions of the protrusions of the W-type member in Example 7. [Figure 67] (a) is a cross-sectional SEM image (250x magnification) of Comparative Example 1, 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 (1000x magnification) of Comparative Example 1, 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 (5000x magnification) of Comparative Example 1, 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 (50,000x magnification) of Comparative Example 1, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. [Figure 71] (a) is a cross-sectional SEM image (5000x magnification) of Comparative Example 2, (c) is an elemental map of W based on EDX analysis, and (d) is an elemental map of Pt. [Figure 72] This is a cross-sectional SEM image (5000x magnification) of Comparative Example 3. [Figure 73] This is a cross-sectional SEM image (50,000x magnification) of Comparative Example 3. [Modes for carrying out the invention]

[0023] 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".

[0024] <First Embodiment> The following describes a first embodiment of the metal joint disclosed herein.

[0025] 1.Metal joint Figure 1 is a schematic cross-sectional view showing a metal joint according to the first embodiment. As shown in Figure 1, the metal joint 100 according to the first embodiment comprises a tungsten-based member (W-based member) 10, an intermediate layer 20, and a copper-based member (Cu-based member) 30. The respective components will be described below.

[0026] (1) W-type members The W-type member 10 is a member containing tungsten (W). The W-type member 10 is not particularly limited as long as it is a solid member containing the element W. That is, the W-type member 10 is not limited to a composition consisting only of tungsten, but may also contain tungsten nitride, tungsten carbide, tungsten carbonitride, copper-tungsten alloy, silver-tungsten alloy, etc. Furthermore, this W-type member 10 may be a composite material (tungsten composite material) in which tungsten material and other metallic materials are combined. Here, examples of metallic materials that may be included in the tungsten composite material include various metallic materials such as copper (Cu), cobalt (Co), nickel (Ni), molybdenum (Mo), platinum (Pt), iron (Fe), gold (Au), and thorium (Th), as well as high-melting-point ceramics such as tria (ThO2) and yttria. Also, for the sake of explanation, a plate-shaped W-type member 10 is shown in Figure 1, but the shape of the W-type member is not particularly limited. For example, W-type members can adopt any shape that a typical metal member can take, such as cylindrical or columnar, without any particular restrictions.

[0027] In the metal joint disclosed herein, a projection is formed on the surface of the W-type member that penetrates into the opposing layer of the W-type member. As shown in Figure 1, in the metal joint 100 according to the first embodiment, an intermediate layer 20 is formed as an opposing layer facing the W-type member 10. In other words, in this embodiment, an intermediate layer 20 is formed between the W-type member 10 and the copper-type member 30, and the projection 12 of the W-type member 10 penetrates into the intermediate layer 20. As a result, an anchoring effect is exerted at the interface between the W-type member 10 and the intermediate layer 20, so that the intermediate layer 20 and the W-type member 10 can be firmly joined.

[0028] The protrusions 12 of this W-based member 10 are composed mainly of W. In this specification, "primarily composed of tungsten" means that elements other than tungsten are intentionally omitted. Therefore, the protrusions 12 may contain unavoidable impurities (metal elements other than W) derived from raw materials or manufacturing processes as minor components. For example, if the total number of metal elements constituting the protrusion 12 is 100 atm%, then if the number of W atoms in the protrusion 12 is 75 atm% or more, it can be said that "a protrusion mainly composed of W has been formed." As the number of W atoms in the protrusion 12 increases, the bonding between the W-based member 10 and the protrusion 12 tends to improve, making it easier for an anchoring effect to occur. From this viewpoint, the number of W atoms in the protrusion 12 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 protrusion 12 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 a cross-sectional SEM image of the metal joint. Inevitable impurities that may be contained in the protrusion 12 include copper (Cu), platinum (Pt), molybdenum (Mo), iron (Fe), cobalt (Co), nickel (Ni), gold (Au), and thorium (Th). Furthermore, tungsten in the protrusion 12 may exist in the form of elemental metal, or in the form of a compound (oxide, etc.) or an alloy with other metallic elements.

[0029] Furthermore, it is preferable that the protrusions 12 have a certain width or more. This suppresses a decrease in bonding strength due to damage to the protrusions 12. Specifically, the average width a of the protrusions 12 is preferably 0.01 μm or more, more preferably 0.03 μm or more, even more preferably 0.05 μm or more, and particularly preferably 0.07 μm or more. On the other hand, if many fine protrusions 12 are formed on the surface of the W-type member 10, a suitable anchoring effect can be generated over the entire interface between the W-type member 10 and the opposing layer. From this viewpoint, the average width a of the protrusions 12 is preferably 1 μm or less, more preferably 0.5 μm or less, even more preferably 0.4 μm or less, and particularly preferably 0.3 μm or less. In this specification, "average width a of the protrusions" is a dimension measured according to the following procedure. First, an SEM image of the cross-section (ion milling surface) of the object to be measured (metal joint) is obtained, and a measurement point is set at an arbitrary position within the protrusions confirmed in the cross-sectional SEM image. Next, measure the minimum dimension of the protrusion passing through this measurement point and consider this to be the "width of the protrusion." Then, following the procedure described above, measure the width of 50 protrusions (minimum dimension of the protrusions) and consider the average of these measurements to be the "average width a of the protrusions."

[0030] Furthermore, the average length b of the projection 12 is preferably 0.05 μm or more, more preferably 0.06 μm or more, even more preferably 0.08 μm or more, and particularly preferably 0.1 μm or more. This allows the projection 12 to penetrate to a deeper position in the opposing layer, thereby enabling a more favorable anchoring effect. Also, from the viewpoint of favorably exhibiting the anchoring effect, there is no particular upper limit to the average length b of the projection 12. For example, the average length b of the projection 12 may be 10 μm or less, 5 μm or less, 2 μm or less, or 1.5 μm or less. In this specification, "projection length" refers to the straight-line distance from the base of the projection (boundary with the W-type member) to the deepest part of the projection that has penetrated into the opposing layer. The "average projection length" is the average value of the lengths of 50 projections confirmed in the cross-sectional SEM image of the measurement target (metal joint), similar to the "projection width" described above.

[0031] Furthermore, it is preferable that the ratio of the average length b of the projection to the average width a of the projection (average aspect ratio b / a) of the projection 12 satisfies a predetermined range. This allows the projection 12 to penetrate to a deep position in the opposing layer while maintaining sufficient strength of the projection 12, thereby producing a suitable anchoring effect and further improving the bonding strength between the W-type member 10 and the opposing layer. Specifically, the average aspect ratio b / a of the projection 12 is preferably 1 or more, more preferably 1.4 or more, even more preferably 2 or more, and particularly preferably 3 or more. On the other hand, the average aspect ratio b / a of the projection 12 is preferably 20 or less, more preferably 17 or less, even more preferably 15 or less, and particularly preferably 13 or less. In addition, from the viewpoint of particularly suitably bonding the W-type member 10 and the opposing layer, it is preferable that both the average width a and the average aspect ratio b / a of the projection 12 of the W-type member 10 are adjusted to a predetermined range. For example, the projection 12 preferably has an average width a of 0.01 μm to 1 μm (more preferably 0.05 μm to 0.5 μm, and even more preferably 0.05 μm to 0.3 μm), and an average aspect ratio b / a of 1 or more (more preferably 2 or more, and even more preferably 3 or more).

[0032] Furthermore, as shown in Figure 1, it is preferable that the projection 12 is a dendritic projection that branches out from the surface of the W-type member 10 toward the opposing layer (intermediate layer 20). By having such dendritic projections 12 penetrate into the interior of the opposing layer, a more favorable anchoring effect can be produced. The average number of branches of these dendritic projections 12 is preferably 0.1 or more, preferably 0.5 or more, preferably 1 or more, and preferably 1.5 or more. This can produce an even more favorable anchoring effect. Also, from the viewpoint of improving the anchoring effect, there is no particular upper limit to the average number of branches of the projection 12. That is, the average number of branches of the projection 12 may be 10 or less, 7.5 or less, 5 or less, or 3 or less. In this specification, "average number of branches of projections" is the average value of the number of branches of 50 projections confirmed by cross-sectional SEM observation of the metal joint.

[0033] Furthermore, the number of protrusions 12 formed relative to the interface length (μm) between the W member 10 and the opposing layer in cross-sectional SEM observation of the metal joint 100 (hereinafter referred to as "protrusion formation density") is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and particularly preferably 0.5 or more. In this way, a more favorable anchoring effect can be achieved by forming a large number of protrusions 12 on the surface of the W member 10. On the other hand, the upper limit of the protrusion formation density is not particularly limited and may be 10 or less, 5 or less, 3 or less, or 2 or less. Note that the above "protrusion formation density" is the average value of the protrusion formation density measured in 50 measurement areas.

[0034] (2) Middle class In the metal joint 100 according to this embodiment, an intermediate layer 20 containing Pt and Cu elements is formed between the W-type member 10 and the Cu-type member 30. This intermediate layer 20 functions as a joining material that joins the W-type member 10 and the Cu-type member 30. Specifically, since the intermediate layer 20 contains Cu, which is the main component of the Cu-type member 30, it is suitably joined to the Cu-type member 30. As described above, in the metal joint 100 according to this embodiment, the protrusion 12 of the W-type member 10 penetrates into the interior of the intermediate layer 20, so the W-type member 10 and the intermediate layer 20 are firmly joined by an anchoring effect. Therefore, according to this embodiment, the W-type member 10 and the Cu-type member 30 can be firmly joined via the intermediate layer 20. Furthermore, in the metal joint 100 according to this embodiment, the difference in thermal expansion coefficients between the W-based member 10 and the Cu-based member 30 can be mitigated in the intermediate layer 20, thus contributing to the stabilization of the joint strength between the W-based member 10 and the Cu-based member 30.

[0035] The intermediate layer 20 only needs to contain Pt and Cu, and its specific structure and the presence of other metallic elements are not particularly limited. For example, as shown in Figure 1, the intermediate layer 20 in this embodiment contains a ternary, two-phase W-Pt-Cu alloy in which a W phase 22 mainly composed of W and a Pt-Cu phase 24 containing Pt and Cu are mixed. In other words, in the intermediate layer 20 shown in Figure 1, the W phase 22 and the Pt-Cu phase 24 exist in a mixed state throughout the entire metal structure. Specifically, in the intermediate layer 20 in this embodiment, a matrix made of Pt-Cu phase 24 is formed, and multiple W phases 22 exist within this matrix. This type of ternary, two-phase W-Pt-Cu alloy exhibits suitable bonding properties to the W-based member 10 because the interface between the W phase 22 and the Pt-Cu phase 24 is stable. Furthermore, since the ternary, two-phase W-Pt-Cu alloy has a Pt-Cu phase 24 containing Cu, it can exhibit suitable bonding properties to the Cu-based member 30 as well. That is, by forming an intermediate layer 20 containing the ternary, two-phase W-Pt-Cu alloy, bonding between the W-based member 10 and the Cu-based member 30 via the intermediate layer 20 can be more favorably performed. As an example of the structure of the ternary, two-phase W-Pt-Cu alloy, there is a structure in which multiple elongated island-shaped W phases are scattered so as to extend in the thickness direction, and Pt-Cu phases are formed to fill the spaces between these multiple W phases (see, for example, Figures 9 and 46). However, the shape of the W phase is not limited to the elongated island shape described above, and may be substantially spherical (see, for example, Figure 57).

[0036] Furthermore, the Pt-Cu phase 24, which is the main phase of the intermediate layer 20, only needs to contain Pt and Cu. In other words, the Pt-Cu phase 24 is not excluded from containing metal elements other than Pt and Cu. Examples of metal elements other than Pt and Cu include W, Mo, Fe, Pd, Ir, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, and Th. Moreover, the Pt-Cu phase 24 does not need to be mainly composed of Pt and Cu; it may be mainly composed of metal elements other than Pt and Cu. For example, among the metal elements mentioned above, those that readily form alloys with Cu (e.g., Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, Th, etc.) can be the main components of the Pt-Cu phase 24. Specifically, when the total number of metal atoms in the Pt-Cu phase 24 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, the total number of Pt and Cu atoms in the Pt-Cu phase 24 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 24 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.

[0037] The number of Pt and Cu atoms in the Pt-Cu phase 24 is not particularly limited. For example, the number of Pt atoms in the Pt-Cu phase 24 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 24 may be 15 atm% or more, 20 atm% or more, 30 atm% or more, or 40 atm% or more. Considering the bonding between the intermediate layer 20 and the Cu-based member 30, 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 in the Pt-Cu phase 24 may be 85 atm% or less, 82.5 atm% or less, or 80 atm% or less. Furthermore, the ratio of the number of Pt atoms to the total number of Pt and Cu atoms (Pt+Cu) in the Pt-Cu phase 24 (Pt / (Pt+Cu)) is not particularly limited. For example, the above ratio of Pt atoms (Pt / (Pt+Cu)) may be 80 atm% or less, 60 atm% or less, 40 atm% or less, or 34 atm% or less. On the other hand, the above ratio of Pt atoms (Pt / (Pt+Cu)) may be 0.5 atm% or more, 1 atm% or more, or 3 atm% or more.

[0038] Furthermore, as mentioned above, the Pt-Cu phase 24 may also contain metal elements other than Pt and Cu (such as W, Mo, Fe, Pd, Ir, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, Th, etc.). Among these metal elements other than Pt and Cu, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, Th, etc. can form alloys (e.g., solid solutions) or eutectic compositions with Cu and become the main components of the Pt-Cu phase 24. Here, it is preferable that the metal elements other than Pt and Cu contained in the intermediate layer 20 are metal elements that form Cu alloys (or eutectic compositions) with a lower melting point than pure Cu (melting point: 1084°C). This makes it possible to more favorably achieve bonding between the W-based member 10 and the Cu-based member 30 via the intermediate layer 20. Specifically, when a W-based member 10 and a Cu-based member 30 are heat-bonded, the Cu element moves (diffuses) from the Cu-based member 30 towards the W-based member 10. This can lead to the formation of voids called Kirkendal voids in the intermediate layer 20 and the Cu-based member 30, potentially reducing the bonding strength between the intermediate layer 20 and the Cu-based member 30. In contrast, if the intermediate layer 20 (for example, the Pt-Cu phase 24) contains a low-melting-point Cu alloy or eutectic composition, the low-melting-point Cu alloy (or eutectic composition) becomes a liquid phase during firing, filling the Kirkendal voids and suppressing the reduction in bonding strength. Examples of such low-melting-point copper alloys or eutectic compositions include alloys of Au and Cu (Au-Cu alloy), alloys of Ba and Cu (Ba-Cu alloy), and eutectic compositions of Ag and Cu.

[0039] On the other hand, the W phase 22 is a phase mainly composed of W and exists inside the Pt-Cu phase 24. As will be described in detail later, this W phase 22 may be generated in the Pt-Cu phase 24 of the intermediate layer 20 during the process of forming the protrusions 12 on the W-system member 10. This W phase 22, like the protrusions 12 of the W-system member 10, is mainly composed of tungsten. The number of W atoms in the W phase 22 is preferably 77.5 atm% or more, more preferably 80 atm% or more, and particularly preferably 82.5 atm% or more. This allows for a more favorable bonding between the W-system member 10 and the intermediate layer 20. The upper limit of the number of W atoms in the W phase 22 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. Furthermore, similar to the projections 12 described above, the W phase 22 may also contain unavoidable impurities derived from the materials and manufacturing process. Examples of these unavoidable impurities in the W phase 22 include copper (Cu), platinum (Pt), molybdenum (Mo), iron (Fe), cobalt (Co), nickel (Ni), gold (Au), and thorium (Th). In addition, tungsten in the W phase 22 may exist in the form of a single metal, or in the form of a compound (oxide, etc.) or an alloy with other metallic elements.

[0040] (3) Cu-based components The Cu-based member 30 is a member containing copper (Cu). This Cu-based member 30 is not particularly limited as long as it contains the element Cu, and various metal members containing the element Cu can be used without any particular restrictions. Examples of materials for such a Cu-based member 30 include pure copper and Pt-Cu alloys. Furthermore, the distribution of the element Cu throughout the Cu-based member 30 does not have to be uniform. As will be described in more detail later, the Cu-based member 30 may be composed of a Pt-Cu alloy (typically a solid solution of Pt and Cu) such that the amount of Pt element increases and the amount of Cu element decreases as it approaches the W-based member 10. Other examples of materials for the Cu-based member 30 include Cu alloys containing one of Ni, Zn, Sn, Mn, Fe, Al, or Be (for example, Cu-Ni alloy, Cu-Zn alloy, Cu-Sn-P alloy). Furthermore, similar to the W-type member 10 described above, Figure 1 shows a plate-shaped Cu-type member 30 for ease of explanation. However, the shape of the Cu-type member is not a limiting factor to the technology disclosed herein. In other words, the Cu-type member can take any shape that a general metal member can take, such as a cylindrical or columnar shape, without any particular restrictions.

[0041] 2. Method for manufacturing a metal joint Next, an example of a method for manufacturing the metal joint 100 according to this embodiment will be described. The metal joint 100 according to this embodiment can be manufactured, for example, by a manufacturing method comprising a Pt-W production step and a Pt-Cu production step. Each step will be described below with reference to Figures 2 and 3. Figure 2 is a schematic cross-sectional view showing an example of the Pt-W production step in the manufacturing method of the metal joint according to the first embodiment. Figure 3 is a schematic cross-sectional view showing an example of the Pt-Cu production step in the manufacturing method of the metal joint according to the first embodiment.

[0042] (a) Pt-W generation process In this process, a layer of Pt-W alloy containing platinum (Pt) and tungsten (W) (Pt-W layer 25) is formed on the surface of the W-type member 10. In this embodiment, a firing process is performed with a Pt source containing platinum (Pt) in contact with the W-type member 10. As a result, a Pt-W layer 25 having an alloy containing Pt and W is generated on the surface of the W-type member 10 (see Figure 2). The Pt-W layer 25 is not particularly limited as long as it contains Pt and W. For example, it is preferable that the Pt-W layer 25 contains an intermetallic compound (e.g., Pt2W) containing Pt and W in a predetermined integer ratio.

[0043] For example, when forming the Pt-W layer 25 by firing, the firing temperature 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 allows the Pt source and the W-based member 10 to react sufficiently to properly form the Pt-W layer 25. On the other hand, the upper limit of the firing temperature 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. The firing time is preferably 0.5 hours or more, and more preferably 1 hour or more. By ensuring a firing time of a certain length or longer, the Pt source and the W-based member 10 tend to react more easily. On the other hand, from the viewpoint of manufacturing efficiency, the upper limit of the firing time is preferably 5 hours or less, more preferably 4 hours or less, and particularly preferably 3 hours or less. In this specification, "firing temperature" refers to the maximum temperature in the firing process, and "firing time" refers to the time for which that maximum temperature is maintained. Furthermore, it is preferable to set the atmosphere during the firing process to a non-oxidizing atmosphere (neutral atmosphere, reducing atmosphere). Examples of reducing gases include hydrogen (H2) gas and hydrocarbon gases (CH4, C3H8, etc.). An example of a neutral gas is nitrogen (N2) gas. It is also possible to use a mixture of these reducing gases and neutral gases. For example, a mixed gas obtained by mixing hydrogen (H2) gas with nitrogen (N2) gas at a concentration of 1% to 5% (e.g., 3%) can be used.

[0044] The Pt source used in this process can be any material containing the Pt element, 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 particles or Pt foil in a predetermined solvent (which may contain resin). By applying such a Pt paste to the surface of the W-based member 10 and reacting the Pt element with the W element, a Pt-W layer 25 can be formed. The Pt paste is not particularly limited except that it contains the Pt element, and conventionally known Pt pastes can be used as long as they do not hinder the effects of the technology disclosed herein. The average particle diameter of the Pt particles in the paste is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 5 μm, and particularly preferably 0.1 μm to 1.0 μm, for example, 0.5 μm. In this specification, "average particle diameter" is the average value of the particle diameters 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 content (volume ratio) is preferably 10 vol% or more, more preferably 15 vol% or more, even more preferably 20 vol% or more, and particularly preferably 25 vol% or more. By supplying such a large amount of Pt, the amount of Pt-W alloy produced increases, so that in the Pt-Cu production process described later, a large average aspect ratio (b / a) can be formed, and a protrusion 12 that exhibits an excellent anchoring effect can be formed. 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 content (volume ratio) is preferably 50 vol% or less, more preferably 40 vol% or less, even more preferably 35 vol% or less, and particularly preferably 30 vol% or less. When the total weight of the Pt paste is 100 wt%, the Pt content (weight ratio) is preferably 50 wt% or more, more preferably 60 wt% or more, even more preferably 70 wt% or more, and particularly preferably 80 wt% or more. On the other hand, the upper limit of the Pt 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 Pt (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.

[0045] Furthermore, from the viewpoint of forming protrusions with a large average aspect ratio by supplying a sufficient amount 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 layer 25 and inhibiting the reaction between the Pt-W alloy and the Cu source in the Pt-Cu generation process described later. The coating thickness of the Pt paste can be easily controlled by adjusting the thickness of the metal mask used when coating the paste.

[0046] Furthermore, when forming the Pt-W layer 25 by firing, it is preferable to perform a drying treatment to dry the Pt paste before firing in order to prevent damage (such as cracks) due to rapid volume changes during the firing process. 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).

[0047] Furthermore, if organic components such as binders are included in the Pt paste, it is preferable to perform a preheating treatment (binder removal treatment) aimed at removing the organic components before the firing treatment. However, if the W-type member 10 is oxidized by this binder removal treatment, the formation of the Pt-W layer 25 may be inhibited by tungsten oxide. For this reason, the organic components (binders, etc.) added to the Pt paste are preferably resin materials (for example, 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.

[0048] (b) Pt-Cu generation process In this process, platinum (Pt) from the Pt-W alloy is moved to the Cu source while the Cu source and the Pt-W layer 25 are in contact. As shown in Figure 3, in this embodiment, a Cu-based member 30 is used as the Cu source, and the firing process is carried out while the Cu-based member 30 and the Pt-W layer 25 are in contact. This causes the movement (typically diffusion) of Pt from the Pt-W layer 25 to the Cu-based member 30 to proceed. Then, Cu is supplied to the Pt-W layer 25 from the Cu-based member 30 after the Pt has moved. During firing, the Cu supplied from the Cu-based member 30 and the Pt from the Pt-W alloy combine in the Pt-W layer 25, and an intermediate layer 20 (see Figure 1) having a Pt-Cu phase 24 is generated. As Pt moves, the removal of Pt from the Pt-W alloy progresses, forming a region mainly composed of W within the Pt-Cu phase 24 of the intermediate layer 20. Of this W-main component region, those formed to come into contact with the W-based member 10 become protrusions 12, while those confined within the matrix of the Pt-Cu phase 24 become the W phase 22. This results in the formation of an intermediate layer 20 having a ternary two-phase W-Pt-Cu alloy, and protrusions 12 penetrating into the Pt-Cu phase 24 of the intermediate layer 20.

[0049] When forming the intermediate layer 20 and the protrusions 12 during the firing process, the firing temperature (maximum temperature during the firing 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 more effectively promotes the diffusion of Pt, allowing for the efficient formation of the protrusions 12 on the W-type member 10. 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 is preferably 1 hour or more, and more preferably 1.5 hours or more. This allows for the more reliable formation of the protrusions 12. On the other hand, from the viewpoint of manufacturing efficiency, the upper limit of the firing time is preferably 3 hours or less, and more preferably 2.5 hours or less.

[0050] Furthermore, it is preferable to set the atmosphere during the firing 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.

[0051] The Cu source used in this process can be any material containing Cu, and its composition is not particularly limited. For example, the Cu source may contain metallic elements other than Cu. An example of such metallic elements other than Cu is the element Pt. Furthermore, by mixing Pt or metallic elements other than Cu with the Cu source, the intermediate layer 20 after production (for example, the Pt-Cu phase 24) can contain an alloy of Cu and other metallic elements. As mentioned above, metallic elements that can form a copper alloy here include gold (Au), nickel (Ni), aluminum (Al), tin (Sn), zinc (Zn), silica (Si), iron (Fe), manganese (Mn), cobalt (Co), and beryllium (Be).

[0052] Furthermore, in this embodiment, a firing process is employed as a treatment for transferring Pt elements from the Pt-W layer 25 to the Cu-based member 30. This firing process is particularly suitable for use when manufacturing low-strength precision parts. For example, by employing the firing process, the W-based member 10 and the Cu-based member 30 can be suitably joined even if the pressure during joining is reduced to 5 kPa or less, thus suitably preventing damage to the parts due to pressure. From the viewpoint of more suitably preventing damage to the parts due to pressure, the pressure applied during the firing process is more preferably 2.5 kPa or less, even more preferably 2 kPa or less, and particularly preferably 1 kPa or less. On the other hand, from the viewpoint of suppressing the occurrence of gaps at the interface between the intermediate layer 20 and the Cu-based member 30, the pressure when joining the W-based member 10 and the Cu-based member 30 is preferably 0.1 kPa or more, more preferably 0.25 kPa or more, and particularly preferably 0.5 kPa or more.

[0053] <Other manufacturing methods> Furthermore, the method for manufacturing a metal joint (a method for joining a W-based member and a Cu-based member) disclosed herein is not limited to the method described above, and various methods can be appropriately adopted.

[0054] For example, in the manufacturing method described above, two types of firing processes, the Pt-W generation process and the Pt-Cu generation process, are carried out separately. However, experiments have confirmed that the metal joint disclosed herein can be manufactured even when the firing process is carried out all at once with a Pt source (e.g., Pt paste) sandwiched between the W-based member and the Cu-based member. Specifically, when the W-based member, Pt paste, and Cu-based member are fired together, a Pt-W layer is formed at the boundary between the W-based member and the Pt paste in the initial stages of firing. As the firing process progresses further, Pt in the Pt-W layer moves toward the Cu-based member, and Cu elements are supplied to the Pt-W layer. As a result, de-Pt is removed from the Pt-W alloy, and protrusions mainly composed of W are formed on the surface of the W-based member. However, from the viewpoint of reliably forming the metal joint disclosed herein, it is preferable to carry out the firing process separately into the Pt-W generation process and the Pt-Cu generation process, as described above. On the other hand, when considering manufacturing efficiency and cost, it is preferable to fire the W-based components, Pt paste, and Cu-based components together.

[0055] Furthermore, in the manufacturing method described above, the Pt-W layer 25 and the Cu-based member 30 are in direct contact. However, the technology disclosed herein is not limited to this manufacturing method. That is, an intermediate metal material (including thin films and paste-dried films) may be interposed between the Pt-W layer and the Cu-based member. The metal joint disclosed herein can also be manufactured by performing a firing process with the Pt-W layer and the Cu source in contact via the intermediate metal material. Examples of such intermediate metal materials include metal members containing Au (e.g., a dried film of Au paste) and metal members containing Pt (e.g., a dried film of Pt paste). In particular, using a metal member containing Au allows for the formation of an intermediate layer containing an Au-Cu alloy, which more effectively suppresses the decrease in bonding strength due to the generation of Kirkendal voids.

[0056] Furthermore, in the manufacturing method described above, the movement (diffusion) of Pt from the Pt-W layer 25 to the copper-based member 30 is caused by performing a heat treatment (sintering treatment) while the copper-based member 30 is in contact with the Pt-W layer 25. However, the movement of Pt from the Pt-W alloy to Cu can proceed if the reaction barrier can be overcome, so it can also be caused by means other than the sintering treatment. For example, the movement of Pt from the Pt-W layer 25 to the copper-based member 30 can be caused by performing a pressurizing treatment while the copper-based member 30 is in contact with the Pt-W layer 25. Even when such diffusion bonding is employed, a reaction equivalent to the sintering treatment described above will proceed, and protrusions 12 can be formed on the surface of the W-based member 10. Also, when performing diffusion bonding, it is preferable to perform the pressurizing treatment all at once with a Pt source (e.g., Pt paste) sandwiched between the W-based member and the Cu-based member. This allows for efficient bonding of the W-based member and the Cu-based member. The movement (diffusion) of Pt from the Pt-W layer 25 to the copper-based member 30 by such pressurization treatment is particularly suitable for manufacturing parts with relatively high strength.

[0057] Furthermore, in the manufacturing method described above, protrusions 12 are formed on the surface of the W-based member 10 by bringing a solid Cu-based member 30 into contact with the Pt-W layer 25 and performing a firing treatment. However, the Cu source in the technology disclosed herein is not limited to a solid Cu-based member. For example, another example of a Cu source in the manufacturing method disclosed herein is a Cu paste obtained by dispersing Cu powder in a predetermined solvent. By applying this Cu paste to the surface of the Pt-W alloy and performing a firing treatment, the Pt element is transferred from the Pt-W alloy to the Cu source (Cu paste), and protrusions can be formed on the surface of the W-based member. In addition, a solid Cu-based member is formed by the sintering of the Cu paste during this firing treatment. Thus, even when a Cu paste is used as the Cu source, the metal joint disclosed herein can be manufactured.

[0058] 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 the miniaturization of the protrusions 12 due to insufficient Cu, and allows for the proper formation of Cu-based members by sintering the Cu paste. 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. The components of the Cu paste other than the Cu 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, detailed explanations are omitted as they do not characterize the disclosed technology. Also, as mentioned above, when forming an intermediate layer 20 containing metal elements other than Pt or Cu, powder of the metal element other than Pt or Cu can be added to the Cu paste. In this case, the powder of the metal element other than Pt or Cu that is added is preferably a powder of a metal element that produces a copper alloy with a melting point lower than that of pure Cu. This helps to suppress the decrease in bonding strength caused by the formation of Kirkendal voids.

[0059] <Second Embodiment> The first embodiment of the technology disclosed herein has been described above. However, the technology disclosed herein is not limited to the above description, and various configurations can be appropriately modified as long as they do not significantly impair the effects of the technology disclosed herein. The second embodiment of the technology disclosed herein will now be described. Figure 4 is a schematic cross-sectional view showing a metal joint according to the second embodiment.

[0060] First, as shown in Figure 1, the intermediate layer 20 of the metal joint 100 according to the first embodiment is composed of a ternary diphase W-Pt-Cu alloy containing a Pt-Cu phase 24 and a W phase 22. However, the composition of the intermediate layer is not limited to the technology disclosed herein. Specifically, as shown in Figure 4, in the metal joint 100A according to the second embodiment, an intermediate layer 20A is formed that does not have a W phase and is mainly composed of a Pt-Cu alloy. Even in such a metal joint 100A, since protrusions 12 that penetrate into the interior of the intermediate layer 20A are formed on the surface of the W-system member 10, an appropriate anchoring effect is generated at the interface between the intermediate layer 20A and the W-system member 10. Furthermore, since this intermediate layer 20A containing the Pt-Cu alloy contains the Cu element, it can exhibit suitable bonding properties to the Cu-system member 30. In other words, even in this metal joint 100A according to the second embodiment, the W-system member 10 and the Cu-system member 30 can be firmly bonded. Since the preferred composition and dimensions of the projection 12 in this embodiment are the same as those of the first embodiment described above, a detailed explanation will be omitted.

[0061] The intermediate layer 20A, which does not have a W phase, can be realized by generating a thin Pt-W layer in the Pt-W generation process described above. When such a thin Pt-W layer is generated, all of the "W-based regions" formed in the subsequent Pt-Cu generation process come into contact with the W-based member. As a result, a metal joint 100A can be obtained, which comprises an intermediate layer 20A that does not have a W phase and a W-based member 10 having protrusions 12 that penetrate the intermediate layer 20A. When forming such an intermediate layer 20A that does not have a W phase, it is preferable to make the thickness of the Pt-W layer in the Pt-W generation process 2000 nm or less (preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 200 nm or less).

[0062] <Third Embodiment> Next, a third embodiment of the technology disclosed herein will be described. Figure 5 is a schematic cross-sectional view showing a metal joint according to the third embodiment.

[0063] First, as shown in Figures 1 and 4, in the first and second embodiments described above, an intermediate layer 20 is formed between the W-based member 10 and the Cu-based member 30. However, the presence or absence of an intermediate layer does not limit the technology disclosed herein. Specifically, as shown in Figure 5, in the metal joint 100B according to the third embodiment, the Cu-based member 30 is directly bonded to the surface of the W-based member 10. In other words, in the third embodiment, the opposing layer facing the W-based member 10 is the Cu-based member 30. In this embodiment, the projection 12 of the W-based member 10 penetrates into this Cu-based member 30. The preferred composition and dimensions of the projection 12 in this embodiment are the same as in the first embodiment described above, so a detailed explanation is omitted.

[0064] Furthermore, this metal joint 100B can be manufactured, similar to the first and second embodiments described above, by bringing a Cu source into contact with a Pt-W alloy formed on the surface of a W-based member and transferring Pt elements from the Pt-W alloy to the Cu source. Specifically, when the transfer of Pt elements from the Pt-W alloy (Pt-W layer 25) shown in Figure 3 to the Cu source (copper-based member 30) occurs, an intermediate layer 20 is formed between the W-based member 10 and the Cu-based member 30, as shown in Figures 1 and 4. However, as this transfer of Pt elements progresses further, all the Pt elements in the Pt-W layer 25 diffuse into the Cu-based member 30, causing the intermediate layer 20 to disappear. In this case, experiments have confirmed that the protrusions 12 formed by the W elements in the Pt-W alloy 25 penetrate into the Cu-based member 30. As a result, as shown in Figure 5, a metal joint 100B is created in which the Cu-based member 30 is directly bonded to the surface of the W-based member 10, and the projection 12 of the W-based member 10 penetrates the Cu-based member 30. In a metal joint 100B with this configuration, the projection 12 provides a suitable anchoring effect at the interface between the W-based member 10 and the Cu-based member 30, thereby enabling a strong and direct bond between the W-based member 10 and the Cu-based member 30.

[0065] Furthermore, in the case of directly joining the W-based member 10 and the Cu-based member 30, as in the third embodiment, it is preferable to make the Pt-W alloy formed on the surface of the W-based member 10 thin and to promote the migration of Pt from the Pt-W alloy to the Cu-based member. Although not intended to limit the technologies disclosed herein, by making the thickness of the Pt-W alloy formed on the surface of the W-based member 10 1 μm or less (preferably 0.5 μm or less, more preferably 0.2 μm or less, and particularly preferably 0.1 μm or less), it becomes easier to diffuse all the Pt elements into the Cu-based member 30, making it easier to achieve direct joining of the W-based member 10 and the Cu-based member 30. Another example of a means of forming a Pt-W alloy of the above thickness is to reduce the amount of Pt elements present between the W-based member 10 and the Cu-based member 30. For example, it is preferable to adjust the amount of Pt source (e.g., Pt paste) applied to the surface of the W-type member 10 so that the Pt thickness is 1.5 μm or less (preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.2 μm or less). This reduces the total amount of Pt elements present between the W-type member 10 and the Cu-type member 30, making it easier to form a thin Pt-W alloy. Note that the above-mentioned Pt thickness does not take into account voids in the Pt source or materials other than Pt. Such Pt thickness is defined as follows. Pt thickness = (weight of Pt in the applied Pt source) / (Pt density at room temperature) / (area where Pt source is applied) Here, the Pt density at room temperature is 21.45 g / cm³. 3

[0066] Furthermore, when the W-type member 10 and the Cu-type member 30 are directly joined using a firing process, the maximum firing temperature 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 promotes the diffusion of Pt into the Cu-type member 30 and prevents the formation of an intermediate layer. On the other hand, the upper limit of the maximum firing temperature is preferably 1200°C or lower, more preferably 1100°C or lower, even more preferably 1085°C (the melting point of copper) or lower, and particularly preferably 1050°C or lower. In this case, the firing time is preferably 0.1 hours or more, and more preferably 0.3 hours or more. This allows Pt to be sufficiently diffused into the Cu-type member 30. On the other hand, from the viewpoint of manufacturing efficiency, the upper limit of the firing time in this process is preferably 5 hours or less, and more preferably 2 hours or less. As described above, "firing temperature" here refers to the maximum temperature in the firing process, and "firing time" refers to the time for which the maximum temperature is maintained.

[0067] In the metal joint 100B according to the third embodiment, as described above, the Pt elements present between the W-based member 10 and the Cu-based member 30 during the manufacturing process diffuse into the Cu-based member 30. Therefore, the Cu-based member 30 in the third embodiment may be a Pt-Cu alloy containing Cu and Pt elements. The distribution of Cu and Pt elements throughout the Cu-based member 30 does not need to be uniform. Typically, the Cu-based member 30 in the third embodiment may be composed of a Pt-Cu alloy such that the amount of Pt elements increases and the amount of Cu elements decreases as it approaches the W-based member 10.

[0068] <Applications to other technologies> Furthermore, the above-described manufacturing method produces a metal joint in which a W-based member and a Cu-based member are firmly joined by performing a Pt-W formation step to create a Pt-W layer by reacting platinum (Pt) and tungsten (W), and a Pt-Cu formation step to move the Pt in the Pt-W layer to copper (Cu). Although not directly related to the technology disclosed herein, the above-described method for manufacturing a metal joint can also be applied to joining metal materials other than tungsten (W) and copper (Cu). Specifically, a predetermined metal X, a metal Y to be joined, and a metal Z that can alloy with both metal X and metal Y are prepared. Then, an XZ alloy formation step is performed to alloy metal X and metal Z. Then, a YZ alloy formation step is performed in which metal Y is brought into contact with this XZ alloy, causing the movement (typically diffusion) of metal Z from the XZ alloy to metal Y. This makes it possible to obtain a metal joint in which a metal member containing metal X and an intermediate layer containing the YZ alloy are joined. In this context, the XZ alloy may be an intermetallic compound. Using an intermetallic compound makes it easier to control the reaction of the XZ alloy compared to a solid solution, thus facilitating control of thickness and composition. Furthermore, it is preferable that the initially formed XZ alloy is thermodynamically less stable than the final product, the YZ alloy. This facilitates the diffusion of the Z component from the relatively unstable XZ alloy to metal Y. According to this method, even if X and Y are metals that do not alloy (typically not forming thermodynamically stable solid solutions or intermetallic compounds), a highly adhesive bond can be obtained through the movement (diffusion) of metal elements during the joining process. Also, because the bond interface after the joining reaction is stable, the formation of Kirkendal voids and the like is less likely to occur during use. Furthermore, it is preferable that the YZ alloy is not an intermetallic compound (typically a solid solution). In other words, it is preferable that Y and Z are a combination that does not easily form intermetallic compounds. This suppresses the formation of low-strength intermetallic compounds. From this viewpoint, it is more preferable that the YZ alloy is a complete solid solution. In the manufacturing method according to the above embodiment, tungsten (W) is selected as metal X, copper (Cu) as metal Y, and platinum (Pt) as metal Z.However, other examples of such manufacturing methods include combinations in which tungsten (W) is selected as metal X, platinum (Pt) as metal Y, and nickel (Ni) as metal Z.

[0069] [Example Test] The following describes some test examples relating to the present invention, but these test examples are not intended to limit the technology disclosed herein.

[0070] 1. Example 1 (1) Sample preparation First, a tungsten plate (thickness 0.3 mm, length 7.5 mm, width 7.5 mm) was prepared as the W-type component. Then, a Pt paste containing Pt was prepared and applied to the entire surface of one side of the W-type component. The Pt paste used in this test was prepared by mixing 21 vol% Pt powder (average particle size: 0.5 μm), a binder (ethylcellulose resin), a dispersant, and a solvent. 2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutyrate was used as the solvent for the Pt paste. In this test, the Pt paste was dried by drying at 120°C for 30 minutes, and then debindered in air (heating rate: 10°C / min, maximum temperature: 200°C, heating time: 3 hours). Next, a copper plate (thickness 0.3 mm, length 20 mm, width 20 mm) was prepared as the Cu source (Cu-type component). Then, the paste-coated surface of the W-type member and the Cu-type member were brought into surface contact, and a 50g alumina block was placed on top of the W-type member, thereby applying a pressure of 0.89kPa to the contact area between the W-type and Cu-type 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 jointed sample in which the W-type and Cu-type members were firmly bonded. N2 gas containing 3% hydrogen (H2) was used as the atmospheric gas during firing.

[0071] (2) Analysis of the sample (a) SEM observation and EDX analysis After cutting the sample from Example 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 6, the analysis results at a magnification of 1000x are shown in Figure 7, the analysis results at a magnification of 3000x are shown in Figure 8, the analysis results at a magnification of 10000x are shown in Figure 9, and the analysis results at a magnification of 50000x are shown in Figure 10. In Figures 6 to 10, (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.

[0072] First, as shown in Figure 6, observation at a low magnification of 250x confirmed the formation of an alloy layer (intermediate layer) mainly composed of a Pt-Cu alloy between the W-type member and the Cu-type member. Although the Pt-Cu alloy, the main component of this intermediate layer, usually has low bonding properties to W-type members, in Example 1, the intermediate layer and the W-type member were strongly bonded. Therefore, higher magnification observation revealed that in Example 1, dendritic protrusions protruded from the surface of the W-type member, and these protrusions penetrated the intermediate layer, which is the opposing layer of the W-type member (see Figures 8, 9, and 16). Furthermore, as shown in the elemental maps in each figure, the main element of these protrusions penetrating the intermediate layer was confirmed to be the W element. From the above, it was found that protrusions mainly composed of the W element were formed on the surface of the W-type member in Example 1, and that these protrusions penetrating the intermediate layer (Pt-Cu phase) created an anchoring effect at the interface between the W-type member and the intermediate layer. Also, as shown in Figure 8, in Example 1, Near the boundary with the W-type member in the intermediate layerIt was found that a layer containing a mixture of W, Pt, and Cu (W-Pt-Cu region) was formed. Further expansion of this W-Pt-Cu region revealed a W-Pt-Cu alloy in which the W phase was mixed into the Pt-Cu phase matrix, as shown in Figures 9 and 10. From these analysis results, it was found that an intermediate layer containing a ternary two-phase W-Pt-Cu alloy is formed between the W-based member and the Cu-based member. It is expected that this intermediate layer containing the W-Pt-Cu alloy further improves the bonding between the W-based member and the Cu-based member.

[0073] (b) Observation of the crystal structure The sample from Example 1 was thinned using FIB-SEM and SEM / EBSD images were acquired. The results are shown in Figure 11. As shown in Figure 11, in Example 1, a Pt-Cu alloy was formed between the W-based member and the Cu-based member, and a W-Pt-Cu alloy was formed at the boundary between the Pt-Cu alloy and the W-based member. Furthermore, it was confirmed that the W crystal grains were smaller in the region of the W-based 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.

[0074] (c) 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. The results of the HAADF-STEM images and elemental mapping images are shown in Figure 12. Figure 13 shows a magnified view of the W-Pt-Cu layer in the HAADF-STEM image of Figure 12. Figure 14 shows the EDX spectrum of region A (W phase in the intermediate layer) in Figure 13. And region B (P in the intermediate layer) t The EDX spectrum of the -Cu phase is shown in Figure 15.

[0075] First, as shown in the elemental map of W in Figure 12, it was confirmed that protrusions penetrating the intermediate layer (W-Pt-Cu layer) were formed on the surface of the W-system member in Example 1. Then, as shown in Figures 14 and 15, the elements W, Cu, Pt, Mo, Fe, and O were mainly identified in the entire W-Pt-Cu layer. Furthermore, as shown in Figures 12 and 14, the elements W, Mo, Fe, and O were mainly identified in the W phase. Of these, the elements Mo and Fe are thought to originate from impurities contained in the W plate. In addition, it is possible that the Mo was detected from the sample folder. On the other hand, as shown in Figures 12 and 15, the elements Cu, Pt, and O were mainly identified in the Pt-Cu phase. The element O, which was identified in both the W phase and the Pt-Cu phase, is thought to originate from oxygen attached in the measurement environment or surface oxidation of the test piece.

[0076] Analysis of Figure 14 revealed that the W phase in the intermediate layer 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 15 revealed that the Pt-Cu phase in the intermediate layer 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.

[0077] (d) Measurement of the dimensions of the protrusions In this analysis, first, a cross-sectional SEM image (magnification: 500,000x) was acquired at the boundary between the W-type member and the intermediate layer (W-Pt-Cu layer) in the sample of Example 1 (see Figure 16). Then, two measurement points were set on the protrusions of the W-type member in the cross-sectional SEM image, and the width of the protrusions at each measurement point was measured. As shown in Figure 16, the width of the protrusions of the W-type member in Example 1 was 0.16 μm to 0.26 μm. In addition, the dimension (length of the protrusion) of the line segment (straight-line distance) connecting the deepest point and the base of one arbitrarily selected protrusion was measured. As shown in Figure 16, the length of the protrusion of the W-type member in Example 1 was 1.4 μm. Based on the measured width and length of the protrusions, the aspect ratio of the protrusions in Example 1 was calculated to be 5.4 to 8.8. Furthermore, as shown in Figure 16, multiple dendritic protrusions branching into two or more were formed in Example 1.

[0078] 2. Example 2 (1) Sample preparation In Example 2, a jointed sample was prepared by joining a W-based member and a Cu-based member under the same conditions as in Example 1, except that the Pt powder content in the Pt paste was reduced to 10 vol%, and the conditions for the binder removal treatment after applying the Pt paste were changed to 160°C for 30 minutes.

[0079] (2) Analysis of the sample (a) SEM observation and EDX analysis SEM observation and EDX analysis were performed on the sample from Example 2 under the same conditions as in Example 1. The analysis results at a magnification of 5000x for Example 2 are shown in Figure 17, the analysis results at a magnification of 50000x for the Pt-Cu region are shown in Figure 18, the analysis results at a magnification of 50000x for the Pt-W layer are shown in Figure 19, the analysis results at a magnification of 50000x for the W-Pt-Cu region are shown in Figure 20, and the analysis results at a magnification of 50000x for the W-based member are shown in Figure 21. In Figures 17 to 20, (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 shown in Figure 17, in Example 2 as well, protrusions penetrating into the intermediate layer (W-Pt-Cu region) were formed on the surface of the W-based member.

[0080] Furthermore, in Example 2, a line segment X1 with a length of 20 μm was drawn from the upper side (Pt-Cu alloy side) to the lower side (W-based member side) of Figure 17(a), and the change in the concentration distribution of W, Pt, and Cu along this line was investigated. The results of this line analysis are shown in Figure 22. In Figure 22, 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 22, (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 22, in the region where the Pt-Cu alloy is present, the presence of Pt and Cu elements was confirmed, but the W element was not confirmed. In the region where the W-Pt-Cu alloy is present, the presence of W, Pt, and Cu elements was confirmed. Furthermore, the region where W-type components exist (12 μm to 20 μm) was almost entirely composed of W element (Figure 22(b)).

[0081] (c) Backscattered electron image analysis In Example 2, the sample was thinned using FIB, and backscattered electron images were obtained in a different field of view than that shown in Figure 17, and various analyses were performed. Figure 23 is a backscattered electron image of Example 2 (1000x magnification). Figure 24(a) is a backscattered electron image of Example 2 (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 24, in Example 2, a region containing a W-Pt-Cu alloy (W-Pt-Cu region), a region containing a Pt-W alloy (Pt-W region), and a region containing a Pt-Cu alloy (Pt-Cu region) were formed in the intermediate layer between the W-based member and the Cu-based member. As shown in Figure 24(c), protrusions penetrating into the Pt-Cu region were formed on the surface of the W-based member. In Example 2, elemental mapping images based on EDX analysis were obtained in both region α and region β in Figure 24(a). The results of the elemental mapping image in region α are shown in Figure 25, and the results of the elemental mapping image in region β are shown in Figure 26. First, as shown in Figure 25, it was confirmed that in the Pt-W region 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 region was 98.5:1.5. Furthermore, the results of the W elemental mapping in Figure 26 also confirmed that protrusions penetrating the intermediate layer (Pt-Cu region) were formed on the surface of the W-based member in Example 2.

[0082] (d)HAADF-STEM analysis Next, in Example 2, HAADF-STEM images and elemental mapping images of the HAADF-STEM images were also acquired. Figure 27 shows the results of the HAADF-STEM images and elemental mapping images for Example 2. Figure 28 is a graph showing the concentration distribution of Pt, Cu, and W on the line segment X2 in Figure 27. As shown in Figures 27 and 28, Example 2 consisted of a W-based member mainly composed of W, a W-Pt-Cu region having a W phase and a Pt-Cu phase, a Pt-W region formed of a Pt-W alloy, and a Pt-Cu region formed of a Pt-Cu alloy. As shown in the elemental mapping results for W in Figure 27, protrusions penetrating the Pt-Cu phase of the intermediate layer (Pt-Cu region) were formed on the surface of the W-based member.

[0083] Furthermore, Figure 29 shows the results of HAADF-STEM images and elemental mapping images at the interface between the W-system member of Example 2, the W phase of the W-Pt-Cu region, and the Pt-Cu phase of the W-Pt-Cu region. Figure 30 is a graph showing the concentration distribution of Pt, Cu, and W along line segment X3 in Figure 29, and Figure 31 is a graph showing the concentration distribution of O and Fe along line segment X3. As shown in Figures 29 and 31, the presence of a small amount of iron (Fe) element was confirmed in the W-system member. The presence of oxygen (O) element is presumed to be due to measurement noise. 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 region and the W-system member.

[0084] In Example 2, electron diffraction was performed in each region from region α to region δ in Figure 27. The results are shown in Figure 32. Figure 32(a) is an image showing the electron diffraction results in region α (W-based material). From these electron diffraction results, it can be seen that the main component in region α (W-based material) is W. Next, Figure 32(b) is an image showing the electron diffraction results in region β (W-Pt-Cu region). From these electron diffraction results, the W phase and Pt-Cu phase were confirmed in region β (W-Pt-Cu region). Furthermore, it was found that at least Cu3Pt is present in the Pt-Cu phase in the W-Pt-Cu region. Finally, Figure 32(c) is an image showing the electron diffraction results in region γ (Pt-W region). In this Pt-W region, 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 32(d) is an image showing the electron diffraction results in region δ (Pt-Cu region). This Pt-Cu region contained at least Cu3Pt as a Pt-Cu alloy.

[0085] Next, as shown in Figure 29 above, in Example 2, HAADF-STEM images and elemental mapping images were obtained at the interface between the W-system member and the W-Pt-Cu region. In addition, in Example 2, HAADF-STEM images and elemental mapping images were obtained in each layer of the W-system member, the Pt-W region, and the Pt-Cu region. The results are shown in Figures 33 to 35. As shown in Figures 29, 34, and 35, in Example 2, a Pt-Cu phase containing Pt and Cu was confirmed in each of the W-Pt-Cu region, the Pt-W layer, and the Pt-Cu region. Furthermore, as shown in Figure 33, in Example 2, a Pt-Cu phase was also confirmed at the grain boundaries of the W-system member. The EDX spectra of the Pt-Cu phase in each of these regions are shown in Figures 37 to 40, and the elemental ratios calculated based on these EDX spectra are shown in Table 1. As shown in Figures 37 to 40 and Table 1, the elemental ratio of the Pt-Cu phase present at the grain boundaries of the W-type material did not differ significantly from the elemental ratio of the Pt-Cu phase in other layers.

[0086] [Table 1]

[0087] (e) Measurement of the dimensions of the protrusions Next, in Example 2, as in Example 1, a cross-sectional SEM image (magnification: 50,000x) was taken at the boundary between the W-type member and the intermediate layer (W-Pt-Cu layer) (see Figure 40). Based on this cross-sectional SEM image, the width and length of the protrusions formed on the surface of the W-type member were measured. As shown in Figure 40, the width of the protrusions on the W-type member in Example 2 was 0.1 μm to 0.4 μm. The length of the protrusions was 1.3 μm. The aspect ratio of the protrusions in Example 2 was 3.3 to 13. Also, as shown in Figure 40, in Example 2, dendritic protrusions branching into three or more branches were formed.

[0088] 3. Example 3 (1) Sample preparation In Example 3, a bonded sample was prepared by joining a W-based member and a Cu-based member under the same conditions as in Example 2, except that the heating rate for the binder removal process after applying the Pt paste was set to 10°C / min, the maximum temperature to 450°C, and the heating time to 30 minutes.

[0089] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Example 3 under the same conditions as in Examples 1 and 2. The analysis results at a magnification of 5000x for Example 3 are shown in Figure 41, and the analysis results at a magnification of 50000x at the boundary between the W-Pt-Cu region and the W-based member are shown in Figure 42. In Figures 41 and 42, (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 shown in Figures 41 to 42, in Example 3 as well, the W-based member and the Cu-based member were joined via an intermediate layer. Furthermore, as shown in Figure 42, in Example 3 as well, protrusions penetrating the intermediate layer (W-Pt-Cu region) were formed on the surface of the W-based member.

[0090] In Example 3, as in Examples 1 and 2, the width and length of the protrusions on the W-type member were measured in a cross-sectional SEM image (magnification: 50,000x) at the boundary between the W-type member and the intermediate layer (W-Pt-Cu layer) (see Figure 43). As shown in Figure 43, the width of the protrusions on the W-type member in Example 3 was 0.07 μm to 0.1 μm. The length of the protrusions was 0.20 μm to 0.33 μm. The aspect ratio of the protrusions in Example 3 was 2.9 to 3.3. Also, as shown in Figure 43, dendritic protrusions were formed in Example 3 as well.

[0091] 4. Example 4 (1) Sample preparation In Example 4, a Pt paste with the same composition as in Example 2 was applied to the surface of a W-type member similar to those in Examples 1-3, and a drying treatment (120°C, 30 minutes) was performed. Then, a binder removal treatment was carried out in an air atmosphere (heating rate: 10°C / min, maximum temperature: 160°C, heating time: 0.5h). Next, a firing treatment was carried out in an N2 gas (containing 3% hydrogen (H2)) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, firing time: 2h). After cooling to room temperature, the surface was observed to show that a Pt firing film had formed and exhibited metallic luster. In addition, a Pt-W alloy was formed between the W-type member and the Pt firing film. Next, Cu paste was applied to the surface of the Pt firing film. The Cu paste used in this test was prepared by kneading 20 vol% Cu powder (average particle size: 0.5 μm), glass powder (SiO2-B2O3 glass), binder (ethylcellulose resin), dispersant, and solvent (2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutyrate). After drying (120°C, 30 minutes), a binder removal treatment was performed in an air atmosphere (heating rate: 10°C / min, maximum temperature: 350°C, firing time: 3 hours) to obtain a four-layer structure in which the W-type component, Pt-W layer, Pt fired film, and Cu dried film were stacked in that order. Then, a firing treatment was performed in an N2 gas (containing 3% hydrogen (H2)) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, firing time: 2 hours). This obtained the sample for Example 4.

[0092] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Example 4 under the same conditions as in Examples 1 to 3. The analysis results at a magnification of 5000x for Example 4 are shown in Figure 44, the analysis results at a magnification of 50000x in the Pt-W region are shown in Figure 45, the analysis results at a magnification of 50000x in the W-Pt-Cu region are shown in Figure 46, the analysis results at a magnification of 50000x in the W-based member are shown in Figure 47, and the analysis results at a magnification of 50000x at the interface between the W-based member and the W-Pt-Cu region are shown in Figure 48. In Figures 44, 45, 47, and 48, (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 Figure 46, (a) is a cross-sectional SEM image, (b) is an elemental map of Pt, (c) is an elemental map of Cu, and (d) is an elemental map of W. First, as shown in Figure 48, it was confirmed that in Example 4, protrusions penetrating into the intermediate layer were formed on the surface of the W-based member. Furthermore, as shown in Figure 46, it was confirmed that a ternary two-phase WP-Cu alloy was formed in the intermediate layer in Example 4. In addition, as shown in Figures 47 and 48, it was confirmed that in Example 4, a Pt-W region mainly composed of a Pt-W alloy was formed in a part of the intermediate layer.

[0093] In Example 4, as in the above-described examples, the width and length of the protrusions on the W-type member were measured in a cross-sectional SEM image (magnification: 50,000x) at the boundary between the W-type member and the intermediate layer (W-Pt-Cu layer) (see Figure 49). As shown in Figure 49, the width of the protrusions on the W-type member in Example 4 was 0.13 μm to 0.23 μm. The length of the protrusions was 0.83 μm to 1.13 μm. The aspect ratio of the protrusions in Example 4 was 3.6 to 8.7. Also, as shown in Figure 49, in Example 4, dendritic protrusions branching into three or more branches were formed.

[0094] 5. Example 5 (1) Sample preparation In Example 5, 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 in Example 2 was applied to the surface of a W plate of the same dimensions as in Example 1. After drying at 120°C for 30 minutes, a binder removal treatment was performed by heat treatment in air (heating rate: 10°C / min, maximum temperature: 160°C, heating time: 0.5h). Subsequently, a 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 W-Pt alloy had been formed on the surface of the W plate. The surface of the W-Pt alloy produced in Example 5 was a rough surface with fine irregularities. Next, in Example 5, a coated area was prepared on the surface of the W-Pt alloy, where Cu paste (Cu source) was applied, and an uncoated area was prepared where Cu paste was not applied. The same Cu paste as in Example 4 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). This obtained the sample of Example 5.

[0095] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Example 5 under the same conditions as in Examples 1-4. The analysis results of the uncoated region of Example 5 are shown in Figures 50 and 51. On the other hand, the analysis results of the coated region are shown in Figures 52-55. First, as shown in Figure 50, a W-Pt alloy with fine irregularities on the surface was formed on the surface of the W plate in the uncoated region. On the other hand, as shown in Figures 52-55, a W-Pt-Cu alloy was formed between the W plate and the Pt-Cu layer in the coated region. Furthermore, as shown in Figure 55, in Example 5, protrusions penetrating into the intermediate layer were formed on the surface of the W-type member. In addition, the width of the protrusions of the W-type member in Example 5 was 0.07 μm, and the length of the protrusions was 0.1 μm to 0.13 μm (see Figure 56). The aspect ratio of the protrusions in Example 5 was 1.4 to 1.9. Furthermore, as shown in Figure 55, almost no branching of the protrusions was observed in Example 5.

[0096] 6. Example 6 (1) Sample preparation A thin layer of Pt paste with the same composition as in Example 2 was applied to the surface of a W plate of the same dimensions as in Example 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 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 W-Pt alloy had been formed on the surface of the W plate. The surface of the W-Pt alloy formed in Example 6 was rough with fine irregularities. Next, in Example 6, after applying Au paste (Au source) to the surface of the W-Pt alloy, it was dried at 120°C for 30 minutes, and then a binder removal treatment was performed in an air atmosphere (heating rate: 10°C / min, maximum temperature: 350°C, firing time: 3h) to obtain a three-layer structure in which the W-type member, Pt-W layer, and dried Au film were laminated in this order. The Au paste used in Example 6 was prepared by kneading 20 vol% Au powder (average particle size: 0.5 μm), glass powder (SiO2-B2O3 glass), binder (ethylcellulose resin), dispersant, and solvent (2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutyrate). Then, a Cu paste with the same composition as in Examples 4 and 5 was applied to the surface of the dried Au film and dried at 120°C for 30 minutes. After that, a firing treatment was carried out in an N2-H2 (3%) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, firing time: 2 hours). This yielded the sample for Example 6.

[0097] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Example 6 under the same conditions as in Examples 1 to 5. The analysis results at a magnification of 5000x for Example 6 are shown in Figure 57, and the analysis results at a magnification of 50000x at the interface between the W-based member and the W-Pt-Cu region are shown in Figure 58. In Figures 57 and 58, (a) is a cross-sectional SEM image, (b) is an elemental map of W, (c) is an elemental map of Cu, (d) is an elemental map of Pt, and (e) is an elemental map of Au. First, as shown in Figure 58, it was confirmed that in Example 6 as well, protrusions penetrating into the intermediate layer were formed on the surface of the W-based member. Furthermore, as shown in Figure 57, it was confirmed that a ternary two-phase WP-Cu alloy was formed in the intermediate layer in Example 6 as well. As described above, it was found that even when another metal layer (Au layer) is interposed between the Pt-W layer and the Cu source, protrusions penetrating into the intermediate layer can be formed on the surface of the W-based member. In Example 6, the width of the protrusions of the W-type member was 0.13 μm to 0.27 μm, and the length of the protrusions was 0.83 μm (see Figure 59). The aspect ratio of the protrusions in Example 6 was 3.1 to 6.4. Furthermore, almost no branching of the protrusions was observed in Example 6.

[0098] 7. Example 7 (1) Sample preparation In Example 7, a Pt paste with the same composition as in Example 2 was applied to the surface of a W-type component similar to those in Examples 1-4, followed by a drying treatment (120°C, 30 minutes). Then, a binder removal treatment was performed in an air atmosphere (heating rate: 10°C / min, maximum temperature: 160°C, heating time: 0.5h). Finally, a firing treatment was performed in an N2 gas (containing 3% hydrogen (H2)) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, firing time: 2h). In Example 5, unlike the other examples, the thickness of the Pt paste application was reduced from 10 μm to 2 μm. As a result, when the coated surface was observed after cooling, a portion of the W-type component was exposed from the surface of the Pt-W layer, and the surface of the Pt-W layer was gray and rough. Next, in this example, a Pt-Cu paste was prepared as a Cu source and applied to the surface of the Pt-W layer. The Pt-Cu paste used in this test was prepared by kneading 20 vol% Pt-Cu powder (a mixture of Pt powder with an average particle size of 0.5 μm and Cu powder with an average particle size of 0.5 μm in a 10:90 ratio), glass powder (SiO2-B2O3 glass), binder (ethylcellulose resin), dispersant, and solvent (2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutyrate). After drying (120°C, 30 minutes), a binder removal treatment was performed in an air atmosphere (heating rate: 10°C / min, maximum temperature: 350°C, heating time: 3 hours), followed by a calcination treatment in an N2 gas (containing 3% hydrogen (H2)) atmosphere (heating rate: 4°C / min, maximum temperature: 1000°C, calcination time: 2 hours). This yielded the sample for Example 7.

[0099] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Example 7 under the same conditions as in Examples 1 to 6. The analysis results at a magnification of 5000x for Example 7 are shown in Figure 57, the analysis results at a magnification of 50000x in the Pt-Cu region are shown in Figure 60, the analysis results at a magnification of 50000x in the first W-Pt-Cu region are shown in Figure 61, the analysis results at a magnification of 50000x in the Pt-W region are shown in Figure 62, the analysis results at a magnification of 50000x in the second W-Pt-Cu region are shown in Figure 63, and the analysis results at a magnification of 50000x at the boundary between the second W-Pt-Cu region and the W-based material are shown in Figure 64. In Figures 60 to 64, (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 Example 7, a line segment X4 with a length of 20 μm was drawn from the upper side (Pt-Cu region side) to the lower side (W-system member side) of Figure 61(a), and the change in the concentration distribution of each element, W, Pt, and Cu, along this line was investigated. The results are shown in Figure 65. In Figure 65, the 0 μm position on the horizontal axis corresponds to the upper end of line segment X4, and the 20 μm position corresponds to the lower end of line segment X4. The vertical axis shows the characteristic X-ray intensity of each element.

[0100] First, as shown in Figure 64, it was confirmed that in Example 7 as well, protrusions penetrating the intermediate layer were formed on the surface of the W-type member. The width of the protrusions on the W-type member in Example 7 was 0.08 μm to 0.15 μm, and the length of the protrusions was 0.47 μm (see Figure 66). The aspect ratio of the protrusions in Example 7 was 3.1 to 5.9. In Example 6, almost no branching of the protrusions was observed. As described above, it was confirmed that even when using Pt-Cu paste as the Cu source, a metal joint with a W-type member having protrusions formed at the interface with the intermediate layer can be manufactured. Furthermore, as shown in Figures 60 to 64, in Example 7, an intermediate layer with a layered structure was formed in which a Pt-Cu region, a first W-Pt-Cu region, a Pt-W region, and a second W-Pt-Cu region were stacked. The formation of this layered intermediate structure is presumed to be due to the diffusion of Pt from the Pt-W layer both from the layer surface and within the layer itself, caused by cracking in the Pt-W layer.

[0101] 8. Comparative Example 1 (1) Sample preparation In Comparative Example 1, Cu paste was applied to the surface of a W-type component and then dried and fired. Specifically, Cu paste with the same composition as in Example 4 was applied to the surface of a W-type component of the same dimensions as in Example 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.

[0102] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Comparative Example 1 under the same conditions as in Example 1. The analysis results at a magnification of 250x for Comparative Example 1 are shown in Figure 67, the analysis results at a magnification of 1000x are shown in Figure 68, the analysis results at a magnification of 5000x are shown in Figure 69, and the analysis results at a magnification of 50000x are shown in Figure 70. In Figures 67 to 70, (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. As a result of these analyses, in Comparative Example 1, no protrusions penetrating the intermediate layer were formed on the surface of the W-based member (see, for example, Figure 70(c)). In addition, no intermediate layer containing alloy material with a mixture of W and Cu was formed. In other words, it was found that even when Cu and W were brought into contact and fired in the absence of Pt (in the absence of a W-Pt alloy), no protrusions penetrating the intermediate layer or an intermediate layer containing a mixture of W and Cu were formed. Furthermore, in this Comparative Example 1 sample, the interface between the W-based member and the Cu layer easily peeled off due to external force.

[0103] 9. Comparative Example 2 (1) Sample preparation In Comparative Example 2, Pt paste was applied to the surface of a plate-shaped W-type member and then dried and fired. Specifically, Pt paste with the same composition as in Example 1 was applied to the surface of a W-type member with the same dimensions as in Example 1. The Pt paste was then dried by a drying treatment 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. As a result, a bonded body was obtained in which a layer containing platinum (Pt) was formed on the surface of the W-type member.

[0104] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Comparative Example 2 under the same conditions as in Example 1. The analysis results at a magnification of 5000x for Comparative Example 2 are shown in Figure 71. In Figure 71, (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 by firing with the Pt source and W source in contact, as in Comparative Example 2, an alloy containing Pt and W (Pt-W alloy) is formed on the surface of the W-based member.

[0105] 8. Comparative Example 3 (1) Sample preparation In Comparative Example 3, Pt-Cu paste was applied to the surface of a plate-shaped W-type member and then dried and fired. Specifically, Pt-Cu paste with the same composition as in Example 7 was applied to the surface of a W-type member with the same dimensions as in Example 1. After drying the paste by drying 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 firing 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.

[0106] (2) Analysis of the sample SEM observation and EDX analysis were performed on the sample of Comparative Example 3 under the same conditions as in Example 1. The analysis results at a magnification of 5000x for Comparative Example 3 are shown in Figure 72, and the analysis results at a magnification of 50000x are shown in Figure 73. As a result of these analyses, when Pt and Cu sources were mixed and fired as in Comparative Example 3, no protrusions penetrating the intermediate layer were formed on the W-type member, even though the Pt and Cu sources were present on the surface of the W-type member during firing. Furthermore, although a Pt-Cu alloy was formed on the surface of the W-type member, this Pt-Cu alloy was not properly bonded to the W-type member. The reason for these results is presumed to be as follows: In Comparative Example 3, the reaction between the mixed Pt and Cu sources occurred preferentially, and a Pt-W alloy was not formed. The Pt-Cu alloy formed by the reaction of the Pt and Cu sources had low reactivity with the W-type member, so elemental movement (diffusion) that would form protrusions on the W-type member did not occur. From this, it was found that in order to form protrusions that penetrate the intermediate layer on the surface of a W-type member, it is better to first create a Pt-W alloy on the surface of the W-type member and then bring the Pt-W alloy into contact with a Cu source and perform a firing treatment.

[0107] 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]

[0108] 10 W system components 12 protrusions 20 Middle Class 22 W phase 24 Pt-Cu phase 25 Pt-W layer 100 Metal joints 200 Cu-based components

Claims

1. Tungsten-based components containing tungsten (W), Copper-based components containing copper (Cu) It has at least the following features: A projection is formed on the surface of the tungsten-based member, which penetrates into the opposing layer of the tungsten-based member. The tungsten-based member is a tungsten member containing 95 atm% or more of the element tungsten (W). A metal joint in which the average width a of the aforementioned protrusions is 0.01 μm or more and 1 μm or less.

2. A tungsten-based member containing tungsten (W), Copper-based components containing copper (Cu) It has at least the following features: A projection is formed on the surface of the tungsten-based member, which penetrates into the opposing layer of the tungsten-based member. The tungsten-based member is a tungsten member containing 95 atm% or more of the element tungsten (W). A metal joint in which the average aspect ratio (b / a) of the aforementioned protrusions is 1 or greater.

3. The metal joint according to claim 1 or 2, wherein the average length b of the protrusions is 0.05 μm or more and 5 μm or less.

4. A tungsten-based member containing tungsten (W), Copper-based components containing copper (Cu) It has at least the following features: A projection is formed on the surface of the tungsten-based member, which penetrates into the opposing layer of the tungsten-based member. The tungsten-based member is a tungsten member containing 95 atm% or more of the element tungsten (W). The aforementioned projection is a dendritic projection that branches out from the surface of the tungsten-based member toward the opposing layer, in a metal joint.

5. The metal joint according to claim 4, wherein the dendritic projection has an average number of branches of 1 or more and 5 or less.

6. The metal joint according to any one of claims 1 to 5, wherein the copper-based member is bonded to the surface of the tungsten-based member, and the protrusion penetrates the copper-based member.

7. A tungsten-based member containing tungsten (W), Copper-based components containing copper (Cu) It has at least the following features: A projection is formed on the surface of the tungsten-based member, which penetrates into the opposing layer of the tungsten-based member. The tungsten-based member is a tungsten member containing 95 atm% or more of the element tungsten (W). A metal joint in which an intermediate layer containing platinum (Pt) and copper (Cu) is formed between the tungsten-based member and the copper-based member, and the protrusion penetrates the intermediate layer.

8. The metal joint according to claim 7, wherein the intermediate layer comprises a W-Pt-Cu alloy in which a W phase containing 80 atm% or more of the tungsten (W) element and a Pt-Cu phase containing platinum (Pt) and copper (Cu) are mixed.

9. The metal joint according to claim 8, wherein the W-Pt-Cu alloy is composed of a plurality of W phases in a matrix consisting of the Pt-Cu phase.

10. A joining method for joining a tungsten-based member containing tungsten (W) and a copper-based member containing copper (Cu), A Pt-W alloy containing platinum (Pt) and tungsten (W) is formed on the surface of the tungsten-based member. With the Cu source in contact with the Pt-W alloy, the platinum (Pt) of the Pt-W alloy is moved to the Cu source, thereby forming protrusions on the surface of the tungsten-based member that penetrate into the opposing layer of the tungsten-based member. The joining method wherein the tungsten-based member is a tungsten member containing 95 atm% or more of the element tungsten (W).

11. A joining method according to claim 10, comprising joining the copper-based member to the surface of the tungsten-based member and causing the protrusion to penetrate the copper-based member.

12. A joining method according to claim 10, wherein an intermediate layer containing platinum (Pt) and copper (Cu) is formed between the tungsten-based member and the copper-based member, and the protrusion is made to penetrate the copper-based member.

13. The joining method according to any one of claims 10 to 12, wherein heat treatment is performed with a platinum (Pt) source interposed between the tungsten-based member and the copper-based member.

14. The joining method according to any one of claims 10 to 12, wherein a pressurized treatment is performed with a platinum (Pt) source interposed between the tungsten-based member and the copper-based member.

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