JP2023085050A - metal joint - Google Patents

Abstract

To achieve proper jointing of a W-based member and a Cu-based member without applying a strong pressure.SOLUTION: A metal joint 100 disclosed herein has a W-based member 10, and an intermediate layer 20 bonded to a surface of the W-based member 10. The intermediate layer 20 of the metal joint 100 contains Pt and Cu, and can thereby be easily jointed to the Cu-based member 200. In the metal joint 100 disclosed herein, a Pt-Cu phase 14 containing Pt and Cu is present at a grain boundary of the W-based member 10. Therefore, the intermediate layer 20 containing Pt and Cu can be properly jointed to the W-based member 10. Specifically, according to the metal joint 100 disclosed herein, a joint body can be obtained in which the W-based member 10 and the Cu-based member 200 are jointed through the intermediate layer 20 without applying a strong pressure.SELECTED DRAWING: Figure 3

Description

The present invention relates to a metal bonded body. Specifically, it relates to a metal bonded body including a tungsten-based member.

Tungsten-based members containing tungsten (W) (hereinafter also referred to as “W-based members”) are characterized by a high melting point and a low coefficient of thermal expansion, and are excellent in reliability in high-temperature environments. Therefore, W-based materials are used for ultra-high-temperature parts exposed to high-temperature environments, such as divertors, 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, so it is used in a state of being joined to a member whose main component is a metal other than tungsten (hereinafter also referred to as a “dissimilar metal member”). often For example, from the viewpoint of material cost and heat dissipation (thermal conductivity), an example of a dissimilar metal member to be joined is a copper-based member containing copper (Cu) (hereinafter also referred to as a “Cu-based member”). .

A diffusion bonding method, for example, is used to bond the W-based member and the Cu-based member. In this diffusion bonding, heating and pressurization are simultaneously performed while the W-based member and the Cu-based member are in close contact with each other. As a result, a W--Cu diffusion layer in which the W element and the Cu element are mutually diffused is formed between the W-based member and the Cu-based member. The members are joined together. 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 at 980° C. and the pressure is set at 106 MPa. Non-Patent Document 1 reports that a W—Cu diffusion layer having a thickness of about 22 nm is formed between a W-based member and a Cu-based member by diffusion bonding under the above conditions.

J. Zhang et al. , Material and design 137 (2018) 473-480

However, the diffusion bonding described above requires application of a very strong pressure (pressure of 10 ⁻¹ to 10 ² MPa (for example, 2 MPa or more)) to the object to be bonded, so it cannot be applied to fragile precision parts. Very difficult. Moreover, in order to perform diffusion bonding appropriately, a bonding apparatus for applying strong pressure while heating the bonding target is required, which may cause an increase in equipment cost.

The present invention has been made to solve the above-mentioned problems, and its main purpose is to develop a novel technique for realizing appropriate bonding between W-based members and Cu-based members without applying strong pressure. to provide.

In order to achieve the above object, the technology disclosed herein provides a metal joined body having the following configuration.

The metal bonded body disclosed herein includes a tungsten-based member containing tungsten (W), and an intermediate layer bonded to the surface of the tungsten-based member and containing platinum (Pt) and copper (Cu). . In the metal bonded body disclosed herein, a Pt—Cu phase containing platinum (Pt) and copper (Cu) exists at the grain boundary of the tungsten-based member.

In the metal bonded body having the above structure, the intermediate layer is bonded to the surface of the W-based member. Since the intermediate layer contains the Cu element, it can be properly bonded to the Cu-based member only by firing at a predetermined temperature. Furthermore, in this metal bonded body, the Pt--Cu phase enters the grain boundary inside the W-based member. As a result, the intermediate layer containing the Pt element and the Cu element and the W-based member can be appropriately bonded. Therefore, according to the metal bonded body disclosed herein, by laminating the W-based member and the Cu-based member with the intermediate layer interposed therebetween and firing, the W-based member and the Cu-based member can be bonded together without applying a strong pressure. can be properly joined.

In a preferred aspect of the metal bonded body disclosed herein, the Pt—Cu phase exists in a region within 10 μm from the interface between the tungsten-based member and the intermediate layer toward the inside of the tungsten-based member. As a result, the W-based member and the intermediate layer can be bonded more appropriately.

In a preferred aspect of the metal bonded body disclosed herein, the tungsten-based member is one selected from the group consisting of tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, and tungsten composite materials. The technology disclosed herein can be applied particularly favorably to these W-based members. An example of the tungsten composite material includes a tungsten composite material containing at least one element selected from the group consisting of copper (Cu), cobalt (Co), nickel (Ni), and molybdenum (Mo).

In a preferred aspect of the metal bonded body disclosed herein, the intermediate layer contains a copper alloy having a lower melting point than copper (Cu). As a result, it is possible to prevent Kirkendall voids from being formed in the intermediate layer or the Cu-based member after the W-based member and the Cu-based member are joined, so that the W-based member and the Cu-based member can be joined more appropriately. be able to. An example of a copper alloy having a melting point lower than that of copper (Cu) is an alloy of copper (Cu) and gold (Au).

In a preferred aspect of the metal bonded body disclosed herein, the intermediate layer includes a W phase containing tungsten (W) as a main component and a Pt—Cu phase containing platinum (Pt) and copper (Cu). containing W--Pt--Cu alloys. As a result, the W-based member and the Cu-based member can be joined more appropriately.

Moreover, the W--Pt--Cu alloy is preferably composed of a plurality of W phases present in a matrix composed of a Pt--Cu phase. By forming the intermediate layer having a structure in which the W phase and the Pt--Cu phase are mixed in this way, the W-based member and the Cu-based member can be joined more appropriately.

1 is a cross-sectional view schematically showing a metal bonded body according to one embodiment; FIG. FIG. 4 is a cross-sectional view schematically showing an example of the structure of an intermediate layer; 1. It is sectional drawing which shows typically the joined body of the W system member and Cu system member produced using the metal joined body shown in FIG. FIG. 3 is a cross-sectional view schematically showing an example of a Pt—W forming step in the method for manufacturing a metal bonded body; FIG. 4 is a cross-sectional view schematically showing an example of a Pt—Cu generation step in the method for manufacturing a metal bonded body; (a) is a cross-sectional SEM image (250 times) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (1000 times) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (10,000 times) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50,000 times) of Example 1, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. SEM images of Example 1 after FIB processing, (a) is an image showing the boundary between a Cu-based member and a W-based member, and (b) and (c) are images in which the boundary portion is further enlarged. be. 1 is a diagram showing an HAADF-STEM image of Example 1. FIG. It is an EDX spectrum in region A (W phase) in FIG. It is an EDX spectrum in region B (Pt--Cu phase) in FIG. (a) is a cross-sectional SEM image (5000×) of Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) in the Pt—Cu region of Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) in the Pt—W region of Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) in the W—Pt—Cu region of Example 2, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) 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. FIG. 14B is a graph showing the concentration distribution of W, Pt, and Cu on line segment X1 in FIG. 14A. In the figure, (a) shows the analysis result of Pt, (b) shows the analysis result of W, and (c) shows the analysis result of Cu. (a) is a backscattered electron image (5000 times) of Example 2, (b) is an enlarged view (20000 times) of region α in (a), and (c) is region β in (a). is an enlarged view (20000 times). (a) is a cross-sectional SEM image (20000×) in region α of Example 2, and (b) to (d) are elemental maps of Cu, Pt and W based on EDX analysis, respectively. (a) is a cross-sectional SEM image (20000×) in region β of Example 2, and (b) to (d) are elemental maps of Cu, Pt and W based on EDX analysis, respectively. FIG. 10 is a diagram showing the results of HAADF-STEM images and elemental mapping images in Example 2; 24 is a graph showing concentration distributions of Pt, Cu, and W on line segment X2 in FIG. 23. FIG. FIG. 10 is a diagram showing the results of an HAADF-STEM image and an elemental mapping image at the interface between the W-based member of Example 2, the W phase in the W—Pt—Cu region, and the Pt—Cu phase in the W—Pt—Cu region. . FIG. 26 is a graph showing concentration distributions of Pt, Cu, and W on line segment X3 in FIG. 25; FIG. 26 is a graph showing concentration distributions of O and Fe on line segment X3 in FIG. 25; (a) is an image showing the result of electron diffraction in region α in FIG. 23(a), (b) is an image showing the result of electron diffraction in region β, and (c) is an image showing the result of electron diffraction in region γ It is an image showing the result of electron beam diffraction, and (d) is an image showing the result of electron beam diffraction in region δ. FIG. 10 is a diagram showing the results of an HAADF-STEM image and an elemental mapping image of the W-based member of Example 2; FIG. 10 shows the results of HAADF-STEM images and elemental mapping images in the Pt—W region of Example 2; FIG. 10 shows the results of HAADF-STEM images and elemental mapping images in the Pt—Cu region of Example 2; It is an EDX spectrum in the Pt--Cu phase in FIG. It is an EDX spectrum in the Pt--Cu phase in FIG. 31 is an EDX spectrum in the Pt--Cu phase in FIG. 30; It is an EDX spectrum in the Pt--Cu phase in FIG. (a) is a cross-sectional SEM image (300 times) of Example 3, and (b) to (e) are elemental maps of W, Cu, Pt, and Au based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50,000 times) in the first Pt--Cu--Au region of Example 3, and (b) to (e) are W, Cu, Pt, and Au elemental maps based on EDX analysis, respectively. is. (a) is a cross-sectional SEM image (5000x) in the first W-Pt-Cu-Au region of Example 3, and (b) to (e) are W, Cu, Pt and Au based on EDX analysis, respectively. Element map. (a) is a cross-sectional SEM image (5000x) in the second Pt--Cu--Au region of Example 3, and (b) to (e) are elemental maps of W, Cu, Pt, and Au based on EDX analysis, respectively. is. (a) is a cross-sectional SEM image (5000x) in the second W—Pt—Cu—Au region of Example 3, and (b) to (e) are W, Cu, Pt, and Au based on EDX analysis, respectively. Element map. (a) is a cross-sectional SEM image (5000x) of the boundary between the second W—Pt—Cu—Au region and the W-based member in Example 3, and (b) to (e) are W based on EDX analysis, respectively. , Cu, Pt, and Au. (a) is a cross-sectional SEM image (5000x) of the W-based member of Example 3, and (b) to (e) are elemental maps of W, Cu, Pt and Au based on EDX analysis, respectively. FIG. 37 is a graph showing concentration distributions of W, Pt, Cu, and Au on line segment X4 in FIG. 36(a). In the figure, (a) shows the analysis result of Pt, (b) shows the analysis result of W, (c) shows the analysis result of Cu, and (d) shows the analysis result of Au. 38 is the EDX spectrum in FIG. 37; 39 is the EDX spectrum in FIG. 38; 40 is the EDX spectrum in FIG. 39; 41 is the EDX spectrum in FIG. 40; 42 is the EDX spectrum in FIG. 41; 43 is the EDX spectrum in FIG. 42; 4 is a cross-sectional SEM image (20000×) of the first W--Pt--Cu--Au region of Example 3. FIG. 4 is a cross-sectional SEM image (20000×) of the second W--Pt--Cu--Au region of Example 3. FIG. (a) is a cross-sectional SEM image (5000×) of Example 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) of the Pt—W region of Example 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) of 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. (a) is a cross-sectional SEM image (50000×) of the W-based member of Example 4, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) of the interface between the W-based member and the W—Pt—Cu region of Example 4, and (b) to (d) are W, Cu, and W based on EDX analysis, respectively. It is an elemental map of Pt. (a) is a cross-sectional SEM image (5000×) of Example 5, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) of the Pt—Cu region of Example 5, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50,000 times) of the first W-Pt-Cu region of Example 5, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. . (a) is a cross-sectional SEM image (50000×) of the Pt—W layer of Example 5, and (b) to (d) are elemental maps of W, Cu, and Pt based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50000×) at the boundary between the second W—Pt—Cu region and the W-based member in Example 5, and (b) to (d) are W and Cu based on EDX analysis, respectively. , Pt. FIG. 58 is a graph showing concentration distributions of Pt, Cu, and W on line segment X5 in FIG. 57; (a) is a cross-sectional SEM image (250 times) of Comparative Example 1, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. (a) is a cross-sectional SEM image (1000 times) of Comparative Example 1, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. (a) is a cross-sectional SEM image (5000×) of Comparative Example 1, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. (a) is a cross-sectional SEM image (50,000 times) of Comparative Example 1, and (b) to (d) are elemental maps of O, Cu, and W based on EDX analysis, respectively. (a) is a cross-sectional SEM image (5000×) of Comparative Example 2, (c) is an elemental map of W based on EDX analysis, and (d) is an elemental map of Pt. 5 is a cross-sectional SEM image (5000×) of Comparative Example 3. FIG. 5 is a cross-sectional SEM image (50000×) of Comparative Example 3. FIG.

An embodiment of the technology disclosed herein will be described below. Matters other than those specifically referred to in this specification, and matters necessary for implementing the technology disclosed herein, can be grasped as design matters by those skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common general technical knowledge in the field. In this specification, "A to B (A and B are numerical values)" means "A or more and B or less".

1. Metal Bonded Body Hereinafter, one embodiment of the metal bonded body disclosed herein will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a metal bonded body according to this embodiment. FIG. 2 is a cross-sectional view schematically showing an example of the structure of the intermediate layer. FIG. 3 is a cross-sectional view schematically showing a joined body of a W-based member and a Cu-based member produced using the metal joined body shown in FIG.

As shown in FIG. 1 , a metal bonded body 100 according to this embodiment includes a tungsten-based member (W-based member) 10 and an intermediate layer 20 . Each configuration will be described below.

(1) W-based member The W-based member 10 is a member containing tungsten (W). The W-based member 10 is not particularly limited as long as it is a solid member containing W element. Further, the W-based member 10 is configured by aggregating a plurality of crystal grains 12 like a general solid metal member. The crystal grains 12 of this W-based member 10 are crystal grains containing W element as a main component. The crystal grains 12 may contain elements other than the W element. That is, the crystal grains 12 of the W-based member 10 are not limited to being composed of only tungsten, and may be made of tungsten nitride, tungsten carbide, tungsten carbonitride, copper-tungsten alloy, silver-tungsten alloy, or the like. Also, the W-based member 10 may be a composite material in which a tungsten material and another metal material are combined. Here, metal materials that can be combined with tungsten materials include copper (Cu), cobalt (Co), nickel (Ni), molybdenum (Mo), platinum (Pt), iron (Fe), gold (Au), thorium Various metal materials such as (Th), thoria (ThO ₂ ), high melting point ceramics such as yttria, and the like can be used. For convenience of explanation, FIG. 1 shows a plate-shaped W-based member 10, but the shape of the W-based member is not particularly limited. For example, the W-based member can adopt any shape that a general metal member can take, such as a cylindrical shape or a columnar shape, without any particular limitations.

Here, in the metal bonded body 100 according to the present embodiment, a Pt—Cu phase containing platinum (Pt) and copper (Cu) is formed at the boundaries (grain boundaries) of the plurality of crystal grains 12 forming the W-based member 10. 14 exist. As a result, the intermediate layer 20 and the W-based member 10, which will be described later, can be properly bonded. Specifically, since the intermediate layer 20 in this embodiment is a layer containing the Pt element and the Cu element, by allowing the similar Pt element and the Cu element to exist on the W-based member 10 side, The difference in thermal expansion can be reduced, and the bonding strength between the W-based member 10 and the intermediate layer 20 can be improved.

The Pt--Cu phase 14 in the W-based member 10 only needs to contain Pt and Cu, and there is no intention to exclude metal elements other than Pt and Cu. Furthermore, the Pt--Cu phase 14 does not have to be composed mainly of Pt and Cu, and may be composed mainly of metal elements other than Pt and Cu. Specifically, the total number of atoms of Pt atoms and Cu atoms when the total number of metal atoms in the Pt—Cu phase 14 is 100 atm% may be 20 atm% or more, or may be 30 atm% or more. , 40 atm % or more. From the viewpoint of improving the bondability between the W-based member 10 and the intermediate layer 20, the total number of atoms of Pt atoms and Cu atoms in the Pt—Cu phase 14 in the W-based member 10 is preferably 50 atm% or more. 65 atm % or more is more preferable, 75 atm % or more is still more preferable, and 85 atm % or more is particularly preferable. On the other hand, the upper limit of the total number of atoms of Pt atoms and Cu atoms in the Pt—Cu phase 14 is not particularly limited, and may be 99.5 atm% or less, 99 atm% or less, or 97.5 atm%. or less, or 95 atm % or less. The “number of atoms” in this specification is a numerical value based on elemental analysis obtained by performing energy dispersive X-ray spectroscopy (EDX) on a cross-sectional SEM image of an alloy material. is. Metal elements other than Pt and Cu include W, Mo, Fe, Pd, Ir, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, and Th. Among these, metal elements that easily form an alloy with Cu (eg, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, Th, etc.) are the main components of the Pt—Cu phase 14 can be

The number of atoms of each of Pt and Cu in the Pt--Cu phase 14 in the W-based member 10 is also not particularly limited. For example, the number of Pt atoms in the Pt—Cu phase 14 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. . Further, the number of Cu atoms in the Pt—Cu phase 14 in the W-based member 10 may be 15 atomic % or more, 20 atomic % or more, 30 atomic % or more, or 40 atomic % or more. may be Considering the bondability between the W-based member 10 and the intermediate layer 20, the number of Cu atoms is preferably 50 atm% or more, more preferably 65 atm% or more, still more preferably 75 atm% or more, and particularly 80 atm% or more. preferable. On the other hand, the upper limit of the number of Cu atoms in the Pt—Cu phase 14 may be 85 atm % or less, 82.5 atm % or less, or 80 atm % or less.

The Pt--Cu phase 14 preferably exists on the surface layer of the W-based member 10. FIG. The term "surface layer of the W-based member" used herein refers to a region including the surface of the W-based member. Specifically, the Pt—Cu phase 14 is formed in a region within 10 μm (typically within 5 μm, preferably within 2 μm) toward the interior of the W-based member 10 from the interface between the W-based member 10 and the intermediate layer 20 . exists, it can be said that the Pt—Cu phase 14 exists in the surface layer of the W-based member 10 . This does not mean that the region where the Pt--Cu phase 14 exists is limited to the surface layer of the W-based member 10. For example, when the total area of the Pt--Cu phase 14 confirmed in the cross-sectional SEM photograph of the W-based member 10 is 100%, the Pt--Cu phase 14 present in the surface layer of the W-based member 10 is 30% or more. Well, it may be 50% or more, or it may be 70% or more.

Moreover, the average particle diameter of the crystal grains 12 of the W-based member 10 is not particularly limited, and may be 20 μm or less, 10 μm or less, 7 μm or less, or 4 μm or less. Also, the lower limit of the average particle diameter of the crystal grains 12 is not particularly limited, and may be 50 nm or more, 100 nm or more, 150 nm or more, or 200 nm or more. In addition, the particle diameter of the crystal grains 12 may not be uniform over the entire W-based member 10 . For example, in the surface layer of the W-based member 10 adjacent to the intermediate layer 20, the W element may diffuse toward the intermediate layer 20, and the grain size of the crystal grains 12 may become smaller. That is, the crystal grains 12 in the surface layer of the W-based member 10 may have a smaller grain size than the crystal grains 12 in other regions. The "average particle size of crystal grains" in the present specification is the number-based arithmetic average value of the circle-equivalent diameters of crystal grains (200 or more randomly measured) obtained by an electron microscope image.

(2) Intermediate Layer The intermediate layer 20 is a layer that is bonded to the surface of the W-based member 10 and contains Pt element and Cu element. This intermediate layer 20 is a layer that functions as a bonding material that bonds the W-based member 10 and the Cu-based member 200 (see FIG. 3). Specifically, since the intermediate layer 20 contains the Cu element, which is the main component of the Cu-based member 200, it can be suitably bonded to the Cu-based member 200 only by firing at a predetermined temperature. On the other hand, since the W-based member 10 of the metal joined body 100 according to the present embodiment has the Pt—Cu phase 14 at the grain boundary, it is appropriately joined to the intermediate layer 20 containing the Pt element and the Cu element. . The intermediate layer 20 only needs to contain Pt and Cu, and the specific structure and the presence of other metal elements are not particularly limited. An example of the structure of the intermediate layer 20 will be described below with reference to FIG.

The intermediate layer 20 shown in FIG. 2 contains a ternary two-phase W--Pt--Cu alloy in which a W phase 22 containing W as a main component and a Pt--Cu phase 24 containing Pt and Cu are mixed. In other words, in the intermediate layer 20 shown in FIG. 2, the W phase 22 and the Pt--Cu phase 24 exist in a mixed state throughout the metal structure. Typically, the intermediate layer 20 forms a matrix composed of a Pt--Cu phase 24, and a plurality of W phases 22 are present in the matrix. In this type of ternary two-phase W—Pt—Cu alloy, the interface between the W phase 22 and the Pt—Cu phase 22 is stable, so it is suitable for bonding to the W-based member 10 (see FIG. 1). can demonstrate their sexuality. Furthermore, since the ternary two-phase W--Pt--Cu alloy has the Pt--Cu phase 24 containing the Cu element, it exhibits suitable bondability even to the Cu-based member 200 (see FIG. 3). can. That is, by forming the intermediate layer 20 having the structure shown in FIG. 2, the W-based member 10 and the Cu-based member 200 can be more preferably joined via the intermediate layer 20. FIG. As an example of the structure of the ternary two-phase W—Pt—Cu alloy, a plurality of long island-shaped W phases are scattered so as to extend in the thickness direction, and the spaces between the plurality of W phases are filled. A structure in which a Pt--Cu phase is formed in the (see, for example, FIGS. 8, 20, etc.). However, the shape of the W phase is not limited to the elongated island shape described above, and may be substantially spherical (for example, see FIG. 38).

Note that the W phase 22 in the intermediate layer 20 shown in FIG. 2 is a phase containing W as a main component, as described above. In the present specification, "mainly composed of tungsten" means that no element other than tungsten is intentionally included. Therefore, a phase containing inevitable impurities (metal elements other than W) derived from raw materials, manufacturing processes, etc. as subcomponents is included in the concept of "W phase" in the present specification. For example, when the total number of metal elements in one phase in the two-phase alloy is 100 atm%, if the number of W atoms in the one phase is 75 atm% or more, "a W phase containing tungsten as a main component It can be said that it is formed. Considering the bondability between the W-based member 10 and the intermediate layer 20, the number of W atoms in the W phase is preferably 77.5 atm% or more, more preferably 80 atm% or more, and particularly 82.5 atm% or more. preferable. The upper limit of the number of W atoms in the W phase is not particularly limited, and may be 99.5 atm% or less, 97.5 atm% or less, or 95 atm% or less. It may be 92.5 atm % or less, or 90 atm % or less. Inevitable impurities that can be contained in the W phase 22 include copper (Cu), platinum (Pt), molybdenum (Mo), iron (Fe), cobalt (Co), nickel (Ni), gold (Au), thorium (Th) and the like. Tungsten in the W phase 22 may exist in the form of a metal simple substance, or may exist in the form of a compound (such as an oxide) or an alloy with another metal element.

On the other hand, the Pt--Cu phase 24 in the intermediate layer 20 may have the same structure as the Pt--Cu phase 14 (see FIG. 1) present at the grain boundaries of the W-based member 10. FIG. As a result, the W-based member 10 and the intermediate layer 20 can be more preferably bonded. In addition, the description of the configuration of the Pt--Cu phase 24 in the intermediate layer 20 (such as the number of atoms of Pt and Cu) overlaps with the description of the Pt--Cu phase 14 in the W-based member 10, so detailed description is omitted. do. Note that such a configuration does not limit the technology disclosed herein. That is, the Pt--Cu phase 24 in the intermediate layer 20 may have a different structure from the Pt--Cu phase 14 in the W-based member 10. FIG.

The Pt--Cu phase 24 in the intermediate layer 20 may also contain metal elements other than Pt and Cu. The Pt--Cu phase 24 in the intermediate layer 20 is W, Mo, Fe, Pd, Ir, Au, Co, Ni, Zn, Al, Sn, Pb, similar to the Pt--Cu phase 14 of the W-based member 10 described above. , Mn, Ag, Th, and the like. Among these, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, Th, etc. form an alloy (for example, a solid solution) or eutectic composition with Cu to form a Pt—Cu phase. 24 main components. Here, the metal elements other than Pt and Cu contained in the intermediate layer 20 are preferably metal elements that form a Cu alloy (or eutectic composition) with a lower melting point than Cu alone (melting point: 1084° C.). As a result, the W-based member 10 and the Cu-based member 200 can be more preferably joined. Specifically, when the W-based member 10 and the Cu-based member 200 are heat-bonded via the intermediate layer 20, the Cu element moves (diffusion) from the Cu-based member 200 toward the W-based member 10. There is a possibility that voids called Kirkendall voids are formed in the layer 20 and the Cu-based member 200 and the bondability between the intermediate layer 20 and the Cu-based member 200 is lowered. On the other hand, 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) is liquid during firing. Since it forms a phase and closes Kirkendall voids, it is possible to suppress deterioration in bondability. Examples of such low melting point copper alloys and eutectic compositions include an alloy of Au and Cu (Au—Cu alloy), an alloy of Ba and Cu (Ba—Cu alloy), and a covalent alloy of Ag and Cu. crystal composition and the like.

Note that the intermediate layer only needs to contain the Pt element and the Cu element, and does not have to be formed of a ternary two-phase W--Pt--Cu alloy as shown in FIG. For example, the intermediate layer in the technology disclosed herein may be made of a Pt--Cu alloy that does not have a W phase and has only a Pt--Cu phase. Even when such a single-phase intermediate layer is formed, it is possible to sufficiently achieve bonding between the W-based member and the Cu-based member via the intermediate layer.

(3) Cu-Based Member Next, a Cu-based member 200, which is an example of a bonding object of the metal bonded body 100 according to the present embodiment, will be described. The Cu-based member 200 shown in FIG. 3 is not particularly limited as long as it is a metal member having suitable bonding properties to the intermediate layer 20 containing the Pt element and the Cu element. Can be used without restrictions. Examples of materials for such a Cu-based member 200 include copper alone and a Pt--Cu alloy. Further, as another example of the material of the Cu-based member 200, a Cu alloy containing any one of Ni, Zn, Sn, Mn, Fe, Al, and Be (eg, Cu—Ni alloy, Cu—Zn alloy, Cu -Sn-P alloy).

An example of the procedure for bonding the Cu-based member 200 and the metal bonded body 100 will be described. Here, the firing process is performed while the intermediate layer 20 of the metal bonded body 100 and the Cu-based member 200 are in contact with each other. As a result, the intermediate layer 20 and the Cu-based member 200 are bonded together, and a bonding material is produced in which the W-based member 10 and the Cu-based member 200 are bonded via the intermediate layer 20 . At this time, since the intermediate layer 20 and the Cu-based member 200 are common in that they contain a Cu element, they can be sintered in a state of being in contact without applying a strong pressure such as in diffusion bonding. can be properly joined. On the other hand, in the present embodiment, since the Pt—Cu phase 14 exists at the grain boundary of the W-based member 10, the difference in thermal expansion between the W-based member 10 and the intermediate layer 20 is reduced, and the W-based member 10 and the intermediate layer 20 can be strongly bonded. As described above, by using the metal bonded body 100 according to the present embodiment, the W-based member 10 and the Cu-based member 200 can be appropriately bonded without applying a strong pressure.

In addition, the joining procedure described above is not intended to limit the technology disclosed herein. For example, if the pressure is not strong enough to damage the W-based member 10 and the Cu-based member 200, the firing process may be performed while applying pressure so as to sandwich the W-based member 10 and the Cu-based member 200. FIG. This suppresses the formation of a gap at the interface between the intermediate layer 20 and the Cu-based member 200, and allows the intermediate layer 20 and the Cu-based member 200 to be bonded more appropriately. At this time, the pressure when the W-based member 10 and the Cu-based member 200 are sandwiched is preferably 5 kPa or less, more preferably 2.5 kPa or less, even more preferably 2 kPa or less, and particularly preferably 1 kPa or less. As a result, damage to the W-based member 10 and the Cu-based member 200 can be reliably prevented. On the other hand, from the viewpoint of suppressing the occurrence of a gap at the interface between the intermediate layer 20 and the Cu-based member 200, the pressure when the W-based member 10 and the Cu-based member 200 are sandwiched is preferably 0.1 kPa or more. 0.25 kPa or more is more preferable, and 0.5 kPa or more is particularly preferable.

2. Method for Manufacturing Metal Bonded Body Next, an example of a method for manufacturing the metal bonded body 100 according to the present embodiment will be described. The metal bonded body 100 according to the present embodiment can be manufactured, for example, by a manufacturing method including a Pt--W forming step and a Pt--Cu forming step. Each step will be described below with reference to FIGS. 4 and 5. FIG. FIG. 4 is a cross-sectional view schematically showing an example of a Pt--W forming step in a method for manufacturing a metal bonded body. FIG. 5 is a cross-sectional view schematically showing an example of the Pt--Cu forming step in the method for manufacturing a metal bonded body.

(a) Pt—W Generation Step In this step, a firing treatment is performed while a Pt source containing platinum (Pt) and the W-based member 10 are in contact with each other. As a result, a Pt--W layer 25 having an alloy containing Pt and W is formed on the surface of the W-based member 10 (see FIG. 4). The Pt--W layer 25 is not particularly limited as long as it contains Pt and W. For example, the Pt--W layer 25 preferably contains an intermetallic compound (eg, Pt ₂ W) containing Pt and W in a predetermined integer ratio.

Furthermore, in this step, part of the Pt element enters the boundaries (grain boundaries) of the crystal grains 12 of the W-based member 10 . As a result, a Pt—W phase 16 containing Pt and W is formed at the grain boundaries inside the W-based member 10 . A large amount of the Pt--W phase 16 is present in the surface layer of the W-based member 10, and a W-rich layer 15 having a larger amount of W element than the Pt--W layer 25 is formed. In other words, the W-rich layer 15 includes crystal grains 12 containing W as the main component and Pt—W phases 16 entering the grain boundaries. The W-rich layer 15 can be suitably formed by adjusting various conditions (heating conditions, etc.) in this step. A specific description will be given below.

For example, the firing temperature in this step is preferably 800° C. or higher, more preferably 850° C. or higher, even more preferably 880° C. or higher, and particularly preferably 900° C. or higher. This tends to make it easier for the Pt element to enter the grain boundaries of the W-based member 10 . On the other hand, the upper limit of the firing temperature in this step is preferably 1300° C. or lower, more preferably 1250° C. or lower, even more preferably 1200° C. or lower, and particularly preferably 1150° C. or lower. The baking time in this step is preferably 0.5 hours or longer, more preferably 1 hour or longer. By ensuring a certain firing time or more in this way, there is a tendency that the Pt element tends to enter the grain boundaries of the W-based member 10 . On the other hand, from the viewpoint of production efficiency, the upper limit of the baking time in this step is preferably 5 hours or less, more preferably 4 hours or less, and particularly preferably 3 hours or less. In this specification, the term "firing temperature" refers to the maximum temperature in the firing process, and the term "firing time" refers to the time during which the maximum temperature is maintained. Moreover, the atmosphere during the firing treatment is preferably set to a non-oxidizing atmosphere (neutral atmosphere, reducing atmosphere). Examples of the reducing gas include hydrogen ( _H2 ) gas, hydrocarbon ( _CH4 , _{C3H8 ,} etc.) gas, and the like. An example of the neutral gas includes nitrogen (N ₂ ) gas. A mixture of these reducing gases and neutral gases can also be used. For example, a mixed gas in which hydrogen (H ₂ ) gas is mixed with nitrogen (N ₂ ) gas at a concentration of 1% to 5% (eg, 3%) can be used.

The Pt source used in this step may be any material containing Pt element, and the detailed components and form are not particularly limited. An example of such a Pt source is a Pt paste in which Pt powder is dispersed in a predetermined solvent. By applying such a Pt paste to the surface of the W-based member 10 and then performing a baking treatment, the Pt—W layer 25 can be formed on the surface of the W-based member 10, and a W-rich layer can be formed on the surface of the W-based member 10. 15 can be formed. The Pt paste is not particularly limited except that it contains Pt particles, and conventionally known Pt pastes can be used as long as they do not inhibit the effects of the technology disclosed herein. As an example, the average particle size of Pt particles in the paste is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 5 μm, particularly preferably 0.1 μm to 1.0 μm, for example 0.5 μm. The “average particle size” used herein is the average value of the particle sizes of a plurality of particles (eg, 100 particles) measured based on SEM observation. The content (volume ratio) of the Pt particles when the total volume of the Pt paste is 100 vol% is preferably 1 vol% or more, more preferably 5 vol% or more, still more preferably 10 vol% or more, and particularly 20 vol% or more. preferable. As a result, poor formation of the Pt--W alloy due to Pt deficiency can be prevented. On the other hand, from the viewpoint of suppressing the viscosity increase of the Pt paste and improving the workability, the upper limit of the content (volume ratio) of the Pt particles is preferably 50 vol% or less, more preferably 40 vol% or less, and 35 vol% or less. More preferably, 30 vol % or less is particularly preferable. The content (weight ratio) of the Pt particles when the total weight of the Pt paste is 100 wt% is preferably 50 wt% or more, more preferably 55 wt% or more, further preferably 60 wt% or more, and particularly 65 wt% or more. preferable. On the other hand, the upper limit of the content (weight ratio) of the Pt particles is preferably 90 wt% or less, more preferably 85 wt% or less, still more preferably 80 wt% or less, and particularly preferably 75 wt% or less. It should be noted that the components of the Pt paste (solvent, binder, dispersant, etc.) other than the Pt particles can be conventionally known components without particular limitations as long as they do not inhibit the effects of the technology disclosed herein. The detailed description is omitted because it does not characterize the technology to be used.

Also, from the viewpoint of forming a sufficiently thick Pt—W layer 25 (intermediate layer 20 after production), the coating thickness of the Pt paste in this step is preferably 10 μm or more, more preferably 20 μm or more, and 30 μm or more. More preferably, 40 μm or more is particularly preferable. 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, still more preferably 70 μm or less, and particularly preferably 60 μm or less. This can prevent unreacted Pt from being generated 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 forming process described below. The coating thickness of the Pt paste can be easily controlled by adjusting the thickness of the metal mask used during paste coating.

From the viewpoint of preventing damage (cracks, etc.) due to sudden changes in volume during the firing process, it is preferable to perform a drying process for drying the Pt paste before the firing process. The heating temperature in such 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 cracks, the upper limit of the heating temperature in the drying treatment is preferably 140° C. or lower, more preferably 130° C. or lower. Moreover, the drying time is preferably 10 minutes or more and 60 minutes or less (for example, about 30 minutes).

In addition, if the Pt paste contains an organic component such as a binder, it is preferable to perform a preliminary heating treatment (binder removal treatment) for the purpose of removing the organic component before the firing treatment. Note that if the W-based member 10 is oxidized by this binder removal treatment, the formation of the Pt—W layer 25 may be inhibited by tungsten oxide. Therefore, the organic component (binder, etc.) added to the Pt paste is preferably a resin material (for example, acrylic resin, etc.) that can be sufficiently thermally decomposed in a non-oxidizing atmosphere. From the viewpoint of reliably removing the organic component, 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 during the binder removal treatment, the upper limit of the heating temperature in the binder removal treatment is preferably 500° C. or less, more preferably 450° C. or less, and further 400° C. or less. Preferably, 350° C. or less is particularly preferable. Moreover, the heating time in the binder removal treatment is preferably 0.5 hours or longer, and more preferably 1 hour or longer. This ensures the removal of organic components. On the other hand, from the viewpoint of production efficiency, the upper limit of the heating time in the binder removal treatment 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.

(b) Pt--Cu Forming Step In this step, the Cu source and the Pt--W layer 25 are subjected to baking while being in contact with each other. The Cu source used in this step is a material containing Cu as its main component. In the example shown in FIG. 5, a Cu-based member 200 to be joined with the W-based member 10 is used as the Cu source. Then, when the baking treatment in this step is performed, Pt moves (typically diffusion) progresses. Cu diffused from the Cu-based member 200 is supplied to the W-rich layer 15 after the Pt has migrated. As a result, the Pt--W phase 16 in the W-based member 10 becomes the Pt--Cu phase. As a result, the W-based member 10 (see FIG. 1) having the Pt--Cu phase 14 at the grain boundaries is formed. On the other hand, in the Pt--W layer 25 from which Pt has migrated, de-Pt progresses from the Pt--W alloy to Cu, and a W phase 22 (see FIG. 2) containing W as the main component is formed. On the other hand, by supplying Pt to Cu, a Pt—Cu phase 24 is formed so as to fill the periphery of the W phase 22 . Thereby, an intermediate layer 20 having a ternary two-phase W--Pt--Cu alloy is formed.

It should be noted that the movement (diffusion) of Pt from the Pt--W alloy to Cu proceeds as long as the reaction barrier can be overcome, so the method is not limited to the above-described firing treatment or the like. When the Pt is caused to move by the firing treatment, the maximum temperature in the firing treatment is preferably 750° C. or higher, more preferably 800° C. or higher, still more preferably 850° C. or higher, and particularly preferably 900° C. or higher. As a result, the Pt--Cu phase 14 can be efficiently formed by promoting the diffusion of Pt more favorably. On the other hand, the upper limit of the highest firing temperature is preferably 1500° C. or lower, more preferably 1400° C. or lower, still more preferably 1300° C. or lower, and particularly preferably 1200° C. or lower. The baking time in this step is preferably 1 hour or longer, more preferably 1.5 hours or longer. As a result, the Pt--W layer 16 that has entered the grain boundary of the W-based member 10 can be properly changed into the Pt--Cu phase 14. FIG. On the other hand, from the viewpoint of production efficiency, the upper limit of the baking time in this step is preferably 3 hours or less, more preferably 2.5 hours or less.

Moreover, the firing atmosphere in this step is preferably set to a non-oxidizing atmosphere (for example, a neutral atmosphere, an inert atmosphere, or a reducing atmosphere). Examples of the reducing gas include hydrogen ( _H2 ) gas, hydrocarbon ( _CH4 , _{C3H8 ,} etc.) gas, and the like. Examples of inert gas include argon (Ar) gas, and examples of neutral gas include nitrogen (N ₂ ) gas and ammonia. A mixture of reducing gas and inert gas (or neutral gas) can also be used. For example, a mixed gas in which hydrogen gas is mixed with nitrogen gas at a concentration of 1% to 5% (eg, 3%) can be used.

The Cu source used in this step is not particularly limited as long as it is a material containing Cu. For example, the Cu source may contain metal elements other than Cu. A Pt element is mentioned as an example of such metal elements other than Cu. Further, by mixing a metal element other than Pt or Cu into the Cu source, the intermediate layer 20 (for example, the Pt—Cu phase 24) after production can contain an alloy of Cu and other metal elements. . As described above, metal elements capable of forming a copper alloy include gold (Au), nickel (Ni), aluminum (Al), tin (Sn), zinc (Zn) silica (Si), iron (Fe ), manganese (Mn), cobalt (Co), and beryllium (Be).

On the other hand, the shape of the Cu source is also not particularly limited. For example, in the example shown in FIG. 5, a Cu-based member 200 is used as the Cu source. However, the Cu source for manufacturing the metal bonded body is not limited to a solid metal member such as the Cu-based member 200 . For example, the Cu source may be a Cu paste in which Cu powder is dispersed in a solvent. When the Cu-based member 200 is used as the Cu source, a joined body (see FIG. 3) in which the W-based member 10 and the Cu-based member 200 are joined via the intermediate layer 20 can be obtained. That is, in the example shown in FIG. 5, manufacturing of the metal joined body 100 and joining of the W-based member 10 and the Cu-based member 200 can be performed simultaneously, which contributes to improvement in working efficiency. On the other hand, when copper paste is used as the Cu source, a metal bonded body 100 (see FIG. 1) in which the Cu-based member 200 is not bonded can be manufactured. Such a single metal bonded body 100 has the advantage of being easy to distribute and sell. Also, a copper thin film deposited by chemical vapor deposition or the like can be used as a Cu source instead of the copper paste. Also in this case, the metal joined body 100 to which the Cu-based member 200 is not joined can be manufactured. Note that the thickness of the Cu source (the thickness of the applied paste or the thickness of the thin film) when forming the single metal bonded body 100 is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, and particularly 60 μm or less. preferable. On the other hand, from the viewpoint of preventing defective formation of the intermediate layer 20 due to lack of Cu element, the lower limit of the thickness of the Cu source is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and particularly 40 μm or more. preferable.

When Cu paste is used as a Cu source, the average particle size of 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, it is 1 μm. The content (volume ratio) of the Cu particles when the total volume of the Cu paste is 100 vol% is preferably 5 vol% or more, more preferably 10 vol% or more, further preferably 15 vol% or more, and particularly 20 vol% or more. preferable. As a result, formation failure of the Pt--Cu phase 14 due to lack of Cu can be prevented. On the other hand, from the viewpoint of suppressing the viscosity increase of the copper paste and improving the workability, the upper limit of the content (volume ratio) of the Cu particles is preferably 55 vol% or less, more preferably 50 vol% or less, and 45 vol% or less. More preferably, 40 vol % or less is particularly preferable. The content (weight ratio) of the Cu particles when the total weight of the Cu paste is 100 wt% is preferably 60 wt% or more, more preferably 65 wt% or more, further preferably 70 wt% or more, and particularly 75 wt% or more. preferable. On the other hand, the upper limit of the content (weight ratio) of Cu particles is preferably 95 wt% or less, more preferably 90 wt% or less, and particularly preferably 85 wt% or less. In addition, the components of the Cu paste (solvent, binder, dispersant, etc.) other than the Cu particles can be conventionally known components without particular limitations as long as they do not inhibit the effects of the technology disclosed herein. The detailed description is omitted because it does not characterize the technology to be used. Further, as described above, when forming the intermediate layer 20 containing a metal element other than Pt or Cu, powder of the metal element other than Pt or Cu can be added to the Cu paste. Although details will be described later, the powder of the metal element other than Pt and Cu to be added at this time is preferably a powder of a metal element that forms a copper alloy having a melting point lower than that of Cu alone.

(2) Other Manufacturing Methods The method of manufacturing the metal bonded body disclosed herein is not limited to the above-described method, and various methods can be employed as appropriate. For example, in the manufacturing method described above, the firing treatment is performed in each of the Pt--W generation process and the Pt--Cu generation process. However, it has been experimentally confirmed that the metal bonded body disclosed herein can be manufactured even when the Pt paste is sandwiched between the W-based member and the Cu source and the firing treatment is performed at once. Specifically, when the W-based member, the Pt paste, and the Cu source are fired together, a Pt—W layer is formed at the boundary between the W-based member and the Pt paste, and Pt is formed at the grain boundary of the W-based member. -W phase is formed. As the firing process progresses further, the Pt in the Pt—W phase within the W-based member moves toward the Cu-based member, and the Cu element is supplied to the grain boundaries of the W-based member to form the Pt—Cu phase. generated. As a result, it is possible to manufacture a metal joined body having a W-based member in which a Pt—Cu phase exists in the grain boundaries. From the viewpoint of reliably forming the metal bonded body disclosed herein, it is preferable to separate the Pt--W generation step and the Pt--Cu generation step from each other and carry out the firing treatment, as described above. On the other hand, in consideration of manufacturing efficiency and manufacturing cost, it is preferable to bake the W-based member, the Pt paste, and the Cu source together.

Further, in the above-described manufacturing method, in the Pt—Cu generation step, diffusion of Pt occurs from the Pt—W layer 25 to the Cu source (Cu-based member 200). A ternary two-phase W--Pt--Cu alloy (see FIG. 2) is produced. However, the intermediate layer of the metal joined body disclosed herein is not limited to a form having a ternary two-phase W--Pt--Cu alloy, and may be formed of a single-phase Pt--Cu alloy. When forming such an intermediate layer having a single-phase Pt--Cu alloy, it is preferable to reduce the thickness of the Pt--W layer in the manufacturing method described above. For example, by setting the thickness of the Pt—W layer to 50 nm or less (preferably 40 nm or less, more preferably 30 nm or less, and even more preferably 20 nm or less), an intermediate layer having a single-phase Pt—Cu alloy can be easily formed. can be formed to In addition, in order to realize such a thin Pt--W layer, as a Pt source in the Pt--W production process, it is preferable to adopt a means of using a Pt paste with a small Pt particle size or a very thin Pt foil. .

Further, in the manufacturing methods described above, the Pt--W layer and the Cu source are brought into direct contact with each other. However, the technique disclosed here is not limited to such a manufacturing method. That is, an intermediate metal material (including a thin film and a dried paste film) may be interposed between the Pt--W layer and the Cu source. The inventor of the present invention has confirmed that the metal bonded body disclosed herein can be produced even if the firing treatment is performed while the Pt—W layer and the Cu source are in contact with each other through the intermediate metal material. . Examples of such an intermediate metal material include a metal member containing Au (for example, a dry film of Au paste) and a metal member containing Pt (for example, a dry film of Pt paste). In particular, when a metal member containing Au is used, an intermediate layer containing an Au—Cu alloy can be formed, thereby preventing deterioration in bondability due to occurrence of Kirkendall voids.

The embodiments of the technology disclosed herein have been described above. Note that the technology disclosed herein is not limited to the above description, and various configurations can be appropriately changed as long as the effects of the technology disclosed herein are not significantly impaired. For example, in the above description, a Cu-based member is presented as an object to be joined by the metal joined body disclosed herein. However, the object to be joined by the metal joined body disclosed herein may be any metal member that can be suitably joined to the intermediate layer containing the Pt element and the Cu element, and may be any metal member other than the Cu-based member. A Pt-based member is an example of an object to be joined other than the Cu-based member. Since the intermediate layer of the metal bonded body disclosed herein contains the Pt element, it can exhibit suitable bondability even to Pt-based members.

[Test example]
Test examples relating to the present invention will be described below, but these test examples are not intended to limit the technology disclosed herein.

1. Example 1
(1) Preparation of Sample First, a tungsten plate (thickness: 0.3 mm, length: 7.5 mm, width: 7.5 mm) was prepared as a W-based member. Then, a Pt paste containing a Pt element was prepared, and the Pt paste was applied to the entire surface of the W-based member. The Pt paste used in this test was obtained by kneading 21 vol % Pt powder (average particle size: 0.5 μm), a binder (ethyl cellulose resin), a dispersing agent, and a solvent. 2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutylate was used as a solvent for the Pt paste. Then, in this test, after drying the Pt paste by performing a drying treatment at 120° C. for 30 minutes, the binder was removed in the atmosphere (heating rate: 10° C./min, maximum temperature: 200° C., heating time: 3 hours) was performed. Next, a copper plate (thickness: 0.3 mm, length: 20 mm, width: 20 mm) was prepared as a Cu source (Cu-based member). Then, the surface of the W-based member to which the paste is applied and the Cu-based member are brought into surface contact, and a 50 g alumina block is placed on the W-based member so that the contact portion between the W-based member and the Cu-based member is zero. A pressure of 0.89 kPa was applied. In this state, a joined body sample in which the W-based member and the Cu-based member are firmly joined is obtained by performing a firing treatment with a temperature increase rate of 4° C./min, a maximum firing temperature of 1000° C., and a firing time of 2 hours. Obtained. N ₂ gas containing 3% hydrogen (H ₂ ) was used as the atmosphere gas during firing.

(2) Sample Analysis (a) SEM Observation and EDX Analysis After cutting the sample of Example 1 along the lamination direction, the cut surface was polished using ion milling, and a cross-sectional SEM image of the cut surface was taken. Further, EDX analysis was performed on the captured cross-sectional SEM image, and elemental mapping images of tungsten (W), copper (Cu), and platinum (Pt) were obtained. FIG. 6 shows the analysis result at a magnification of 250 times, FIG. 7 shows the analysis result at a magnification of 1000 times, FIG. 8 shows the analysis result at a magnification of 10000 times, and FIG. 9 shows the analysis result at a magnification of 50000 times. 6 to 9, (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. .

First, as shown in FIG. 6, when observed at a low magnification of 250 times, an alloy layer (intermediate layer) mainly composed of a Pt—Cu alloy is formed between the W-based member and the Cu-based member. was confirmed. In Example 1, the intermediate layer and the W-based member were firmly bonded, although the Pt--Cu alloy, which is the main component of the intermediate layer, normally has low bondability to the W-based member. Therefore, as shown in FIGS. 8(a) and 8(b), as a result of observation at a higher magnification (10,000 times), in Example 1, elements other than W were present inside the W-based member (grain boundaries). It was confirmed that the ingredients were included. Then, as shown in FIGS. 8(c) and 8(d), it was confirmed that the elements that entered the interior of the W-based member were the Pt element and the Cu element. From the above, the W-based member of Example 1 has a Pt—Cu phase containing Pt element and Cu element at the grain boundary, and the Pt—Cu phase separates the W-based member and the intermediate layer ( It was presumed that the bondability with the Pt--Cu alloy) was improved. Further, as shown in FIG. 7, in Example 1, a layer (W—Pt—Cu region) in which W, Pt, and Cu are mixed is formed at the boundary between the intermediate layer and the W-based member. Do you get it. When this W--Pt--Cu region was further enlarged, as shown in FIGS. 8 and 9, a W--Pt--Cu alloy in which the W phase was mixed in the Pt--Cu phase matrix was confirmed. From the above analysis results, it was found that an intermediate layer having a ternary two-phase W--Pt--Cu alloy was formed between the W-based member and the Cu-based member. It is expected that the intermediate layer containing this W--Pt--Cu alloy further improves the bondability between the W-based member and the Cu-based member.

(b) Observation of crystal structure Using FIB-SEM, the sample of Example 1 was sliced and SEM/EBSD images were obtained. The results are shown in FIG. As shown in FIG. 10, in Example 1, a Pt--Cu alloy is formed between the W-based member and the Cu-based member, and W--Pt is formed at the boundary between the Pt--Cu alloy and the W-based member. -Cu alloy is formed. It was also confirmed that in the region of the W-based member in contact with the W—Pt—Cu alloy, the W crystal grains were smaller than in other regions. It is presumed that this is because W was supplied from the region in order to produce a W--Pt--Cu alloy. In the region where the crystal structure of the W-based member is reduced, as shown in FIG. 8, the Pt—Cu phase enters the crystal grain boundary. Improvement can be expected.

(c) Elemental Mapping In addition, in this test, HAADF-STEM (High Angle Annular Dark-Field Scanning Transmission Electron Microscopy) images (magnification: 50000 times) of test pieces sliced by FIB-SEM were obtained. A HAADF-STEM image is shown in FIG. FIG. 12 shows the EDX spectrum of region A (W phase in the intermediate layer) in FIG. FIG. 13 shows the EDX spectrum of region B (the P—Cu phase in the intermediate layer).

First, as shown in FIG. 12, W element, Mo element, Fe element, and O element were mainly confirmed in the W phase in the intermediate layer. Among these elements, the Mo element and the Fe element are considered to be derived from impurities contained in the W-based member. Also, regarding Mo, there is a possibility that something included in the sample folder was detected. On the other hand, as shown in FIG. 13, Cu element, Pt element, and O element were mainly confirmed in the Pt—Cu phase in the intermediate layer. Note that the O element confirmed in both the W phase and the Pt--Cu phase is considered to be derived from oxygen adhering in the measurement environment and surface oxidation of the test piece.

As a result of analyzing FIG. 12, the number of W atoms in the W phase in the intermediate layer is 84.57 atm %, the number of Cu atoms is 2.56 atm %, and the number of Pt atoms is 0.06 atm %. there were. In addition, the W phase contained 12.81 atm % of molybdenum (Mo), which is an impurity, and it is considered that this was detected in the sample folder. On the other hand, as a result of analyzing FIG. 13, the number of W atoms in the Pt—Cu phase in the intermediate layer is 2.31 atm%, the number of Cu atoms is 78.13 atm%, and the number of Pt atoms is 15.59 atm%. %Met. In addition, the Pt--Cu phase contained 3.97 atm % of molybdenum (Mo) as an impurity. It is considered that this Mo also detected what is included in the sample folder.

2. Example 2
(1) Preparation of samples In Example 2, the content of Pt powder in the Pt paste was reduced to 10 vol%, and the conditions for the binder removal treatment after coating of the Pt paste were changed to 160°C for 30 minutes. A bonded body sample was prepared by bonding a W-based member and a Cu-based member under the same conditions as in Example 1.

(2) Sample Analysis (a) SEM Observation and EDX Analysis The sample of Example 2 was subjected to SEM observation and EDX analysis under the same conditions as in Example 1. The analysis result of Example 2 at a magnification of 5000 times is shown in FIG. 14, the analysis result of the Pt--Cu region at a magnification of 50000-fold is shown in FIG. FIG. 17 shows the analysis result of the W--Pt--Cu region at a magnification of 50,000, and FIG. 18 shows the analysis result of the W-based member at a magnification of 50,000. 14 to 18, (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. be. Further, for Example 2, a line segment X1 having a length of 20 μm is drawn from the upper side (Pt—Cu alloy side) to the lower side (W-based member side) in FIG. Changes in the concentration distribution of each element of Cu were investigated. The results of such line analysis are shown in FIG. The position of 0 μm on the horizontal axis of FIG. 19 corresponds to the upper end of the line segment X1, and the position of 20 μm corresponds to the lower end of the line segment X1. The vertical axis indicates the characteristic X-ray intensity of each element. In FIG. 19, (a) shows the analysis results of Pt, (b) shows the analysis results of W, and (c) shows the analysis results of Cu. As shown in FIG. 19, in the region where the Pt—Cu alloy exists, the presence of the Pt element and the Cu element was confirmed, but the W element was not confirmed. In the region where the W--Pt--Cu alloy exists, each of the W element, the Pt element and the Cu element was confirmed. Most of the region (12 μm to 20 μm) where the W-based member exists was the W element (FIG. 19B), but in the surface layer (region around 13.8 μm) of the W-based member, the Pt element and Cu A peak indicating the presence of the element was confirmed. From this, it was confirmed that in Example 2 as well, the Pt element and the Cu element entered the grain boundaries of the W-based member. The Pt--Cu phase present at the grain boundaries of this W-based member can also be confirmed in the elemental map shown in FIG.

(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 from that shown in FIG. 14 to perform various analyses. 20(a) is a backscattered electron image (5000 times) of Example 2, (b) is an enlarged view (20000 times) of region α in (a), and (c) is It is an enlarged view (20000 times) of area|region (beta). As also shown in FIG. 20, in Example 2, a region containing a W—Pt—Cu alloy (W—Pt—Cu region) is provided in the intermediate layer between the W-based member and the Cu-based member. , a region containing a Pt--W alloy (Pt--W region) and a region containing a Pt--Cu alloy (Pt--Cu region) were formed. In Example 2, an elemental mapping image based on EDX analysis was obtained in each of the regions α and β in FIG. 20(a). FIG. 21 shows the result of the elemental mapping image in the region α, and FIG. 22 shows the result of the elemental mapping image in the region β. First, as shown in FIG. 21, in the Pt—W region in the region α, a small amount of Pt—Cu crystal grains are present between Pt—W crystal grains having a grain size of about 100 to 500 nm. confirmed. The area ratio between the Pt--W crystal grains and the Pt--Cu crystal grains in this Pt--W region was 98.5:1.5. Also, as shown in FIG. 22, it was confirmed in the backscattered electron image that the Pt element and the Cu element entered the crystal grain boundary of the W-based member. The area ratio of the Pt--Cu phase and the W phase in the W--Pt--Cu region shown in FIG. 22 was 52.9:47.1.

(d) HAADF-STEM Analysis Next, in Example 2, an HAADF-STEM image and an elemental mapping image of the HAADF-STEM image were also acquired. 23 is a diagram showing the results of HAADF-STEM images and elemental mapping images of Example 2. FIG. FIG. 24 is a graph showing concentration distributions of Pt, Cu, and W on line segment X2 in FIG. As shown in FIGS. 24 and 23, in Example 2, a W-based member mainly composed of W, a W—Pt—Cu region having a W phase and a Pt—Cu phase, and a Pt—W A Pt--W region made of an alloy and a Pt--Cu region made of a Pt--Cu alloy were formed.

Further, FIG. 25 shows an HAADF-STEM image and an elemental mapping image at the interface between the W-based member of Example 2, the W phase in the W--Pt--Cu region, and the Pt--Cu phase in the W--Pt--Cu region. It is a figure which shows a result. 26 is a graph showing concentration distributions of Pt, Cu, and W on line segment X3 in FIG. 25, and FIG. 27 is a graph showing concentration distributions of O and Fe on line segment X3. As shown in FIGS. 25 and 27, the existence of a small amount of iron (Fe) element was confirmed in the W-based member. Also, the oxygen (O) element is presumed to be due to measurement noise. These Fe element and O element are present in any region, and no clear uneven distribution was confirmed at the interface between the Pt--Cu phase in the W--Pt--Cu region and the W-based member.

Further, in Example 2, electron beam diffraction was performed in each of regions α to δ in FIG. The results are shown in FIG. FIG. 28(a) is an image showing the result of electron beam diffraction in the region α (W-based member). From the electron beam diffraction result, it can be seen that W is the main component in the region α (W-based member). Next, FIG. 28(b) is an image showing the result of electron beam diffraction in the region β (W--Pt--Cu region). From the electron beam diffraction results, W phase and Pt--Cu phase were confirmed in the region β (W--Pt--Cu region). Furthermore, it was found that at least Cu ₃ Pt was present in the Pt--Cu phase in the W--Pt--Cu region. FIG. 28(c) is an image showing the result of electron beam diffraction in the region γ (Pt—W region). In the Pt--W region, a Pt--Cu alloy was also confirmed in addition to the Pt--W alloy. The Pt--W layer contained at least Pt ₂ W as the Pt--W alloy and at least Cu ₃ Pt as the Pt--Cu alloy. FIG. 28(d) is an image showing the result of electron beam diffraction in the region δ (Pt—Cu region). The Pt--Cu region contained at least Cu ₃ Pt as a Pt--Cu alloy.

Next, as shown in FIG. 25 described above, in Example 2, an HAADF-STEM image and an elemental mapping image at the interface between the W-based member and the W--Pt--Cu region are obtained. In addition, in Example 2, HAADF-STEM images and elemental mapping images were obtained for each layer of the W-based member, the Pt--W region, and the Pt--Cu region. The results are shown in Figures 29-31. As shown in FIGS. 25, 30 and 31, in Example 2, in each of the W—Pt—Cu region, the Pt—W layer, and the Pt—Cu region, the Pt—Cu phase having Pt and Cu was confirmed. Furthermore, as shown in FIG. 29, in Example 2, a Pt—Cu phase was confirmed even at the grain boundaries of the W-based member. 32 to 35 show the EDX spectra of the Pt—Cu phase in each of these regions, and Table 1 shows the element ratios calculated based on these EDX spectra. As shown in FIGS. 32 to 35 and Table 1, the element ratio of the Pt—Cu phase present at the grain boundaries of the W-based member was not significantly different from the element ratio of the Pt—Cu phase in other layers.

As a result of the above analysis, even in Example 2, the Pt--Cu phase entered the grain boundaries of the W-based member. From this, by applying the Pt paste to the W-based member and performing the firing process, the Pt element enters the crystal grain boundary of the W-based member to generate the Pt--W phase, and then the Pt--Cu phase is generated. It is thought that Also in Example 2, a W--Pt--Cu alloy was formed between the Pt--W region and the W-based member.

3. Example 3
(1) Preparation of samples In Example 3, a Pt paste having the same composition as in Example 2 was applied to the surface of the same W-based member as in Examples 1 and 2, and dried (120°C for 30 minutes). After that, a binder removal treatment (heating rate: 10° C./min, maximum temperature: 160° C., heating time: 0.5 h) was performed in an air atmosphere. Next, firing treatment (heating rate: 4° C./min, maximum temperature: 1000° C., firing time: 2 h) was performed in an N ₂ gas (containing 3% hydrogen (H ₂ )) atmosphere. When the surface was observed after cooling to room temperature, a Pt baked film was formed and exhibited metallic luster. Also, a Pt--W alloy was produced between the W-based member and the Pt fired film. Next, an Au paste was applied to the surface of the Pt fired film. The Au paste used in this test consisted of 20 vol% Au powder (average particle diameter: 0.5 μm), glass powder (SiO ₂ —B ₂ O ₃ glass), binder (ethyl cellulose resin), It is obtained by kneading a dispersing material and a solvent (2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutylate). After that, after performing drying treatment (120° C., 30 minutes), binder removal treatment (heating rate: 10° C./min, maximum temperature: 350° C., firing time: 3 hours) was performed in the atmosphere, W-based member , a Pt--W layer, a Pt sintered film, and an Au dried film were laminated in this order to obtain a four-layer structure. Then, the same Cu-based member as in Examples 1 and 2 was brought into contact with the Au dry film of such a four-layer structure and a load (50 g of alumina block) was placed on it, and N ₂ gas (3% hydrogen (H ₂ ) Firing treatment (heating rate: 4°C/min, maximum temperature: 1000°C, firing time: 2h) was performed in an atmosphere containing 2). As a result, a joined body sample in which the W-based member and the Cu-based member were firmly joined was obtained.

(2) Sample Analysis (a) SEM Observation and EDX Analysis The sample of Example 3 was subjected to SEM observation and EDX analysis under the same conditions as in Example 1. FIG. 36 shows the analysis results of Example 3 at a magnification of 300 times. 37 shows the analysis results of the first Pt--Cu--Au region in FIG. 36 at a magnification of 50,000; FIG. 39 shows the analysis result of the −Cu—Au region at a magnification of 50,000, and FIG. 40 shows the analysis result of the second W—Pt—Cu—Au region at a magnification of 50,000. Further, FIG. 41 shows the analysis result of the boundary between the second W--Pt--Cu--Au region and the W-based member at a magnification of 50,000, and FIG. 42 shows the analysis result of the W-based member at a magnification of 50,000. 36 to 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. and (e) is an elemental map of Au.

Further, in Example 3, a line segment X4 having a length of about 300 μm is drawn from the upper side (first Pt--Cu--Au region side) to the lower side (W-based member side) in FIG. , Pt, Cu, and Au. The results are shown in FIG. The 0 μm position on the horizontal axis of FIG. 43 corresponds to the upper end of the line segment X4, and the 300 μm position corresponds to the lower end of the line segment X4. The vertical axis indicates the characteristic X-ray intensity of each element. In FIG. 43, (a) shows the analysis results of Pt, (b) shows the analysis results of W, (c) shows the analysis results of Cu, and (d) shows the analysis results of Au. there is Furthermore, in Example 3, EDX spectra in each field of view shown in FIGS. 37 to 42 were obtained. EDX spectra in each of these fields of view are shown in FIGS. 44 to 49. FIG.

First, as shown in FIGS. 41, 42, 48, and 49, it was confirmed that the Pt element and the Cu element entered the grain boundaries of the W-based member also in Example 3. From this, even when the firing treatment is performed with the Au layer interposed between the Pt—W layer and the Cu source (Cu-based member), the Pt—Cu phase is formed at the grain boundary of the W-based member. It was confirmed that

Further, as shown in FIGS. 36 to 40, in Example 3, a region containing a Pt--Cu--Au alloy (t--Cu--Au region) and a region containing a W--Pt--Cu--Au alloy (W--Pt-- Cu—Au regions) were alternately formed in the thickness direction. The cause of the formation of such a layered structure is that as a result of the Pt--W layer being formed thick, cracks occur in the Pt--W layer, and Pt from the Pt--W layer diffuses into both the layer surface and the inside of the layer. presumed to have arisen from Further, as shown in FIGS. 50 and 51, the first W--Pt--Cu--Au region and the second W--Pt--Cu--Au region were each magnified and observed. was formed. From this, it was confirmed that a quaternary two-phase W--Pt--Cu--Au alloy containing a W phase and a Pt--Cu--Au phase was formed in the intermediate layer of Example 3. Further, as shown in FIGS. 36 to 41, the intermediate layer of Example 3 did not have Kirkendall voids as confirmed in Example 1 (see FIG. 7). This is presumably because the intermediate layer of Example 3 contained an Au--Cu alloy with a low melting point, and the Au--Cu alloy turned into a liquid phase during firing to close the Kirkendall voids.

4. Example 4
(1) Preparation of Sample In Example 4, a joined body sample was prepared in the same procedure as in Example 3, except that Cu paste was applied to the surface of the fired Pt film instead of the Au paste. The Cu paste used in this test consisted of 20 vol% Cu powder (average particle size: 0.5 μm), glass powder (SiO ₂ —B ₂ O ₃ glass), binder (ethyl cellulose resin), It is obtained by kneading a dispersing material and a solvent (2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutylate).

(2) Sample Analysis (a) SEM Observation and EDX Analysis The sample of Example 4 was subjected to SEM observation and EDX analysis under the same conditions as in Example 1. FIG. 52 shows the analysis result of Example 4 at a magnification of 5000 times, FIG. 53 shows the analysis result of the Pt--W region at a magnification of 50000-fold, and FIG. FIG. 55 shows the analysis result of the W-based member at a magnification of 50,000, and FIG. 56 shows the analysis result of the interface between the W-based member and the W--Pt--Cu region at a magnification of 50,000-fold. 52 to 56, (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. be.

First, as shown in FIG. 55, also in Example 4, it was confirmed that the Pt—Cu phase entered the grain boundaries of the W-based member. Furthermore, as shown in FIGS. 54 and 56, it was confirmed that a ternary two-phase WP—Cu alloy was formed in the intermediate layer in Example 4 as well. Further, as shown in FIGS. 52 and 53, in Example 4, it was confirmed that a Pt--W region containing a Pt--W alloy as a main component was formed in part of the intermediate layer.

5. Example 5
(1) Preparation of samples In Example 5, a Pt paste having the same composition as in Example 2 was applied to the surface of the same W-based member as in Examples 1 to 4, and dried (120°C, 30 minutes). After that, a binder removal treatment (heating rate: 10° C./min, maximum temperature: 160° C., heating time: 0.5 h) was performed in an air atmosphere. Then, firing treatment (heating rate: 4° C./min, maximum temperature: 1000° C., firing time: 2 hours) was performed in an N ₂ gas (containing 3% hydrogen (H ₂ )) atmosphere. Note that in Example 5, unlike the other examples, the thickness of the Pt paste applied was reduced from 10 μm to 2 μm. Therefore, when the coating surface after cooling was observed, part of the W-based member 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 20 vol% Pt—Cu powder (Pt powder with an average particle size of 0.5 μm and Cu powder with an average particle size of 0.5 μm were mixed at a ratio of 10:90. material), glass powder (SiO ₂ -B ₂ O ₃ based glass), binder (ethyl cellulose based resin), dispersing agent, solvent (2,2,4-Trimethyl-1,3-pentanediol 1-Monoisobutylate) It is a mixture of Then, after performing a drying treatment (120° C., 30 minutes), a binder removal treatment (heating rate: 10° C./min, maximum temperature: 350° C., heating time: ₃ h) is performed in an air atmosphere. Firing treatment (heating rate: 4° C./min, maximum temperature: 1000° C., firing time: 2 h) was performed in a gas atmosphere (containing 3% hydrogen (H ₂ )). As a result, a joined body sample was obtained in which an intermediate layer containing platinum (Pt) and copper (Cu) was formed on the surface of the W-based member.

(2) Sample Analysis The sample of Example 5 was subjected to SEM observation and EDX analysis under the same conditions as in Example 1. FIG. 57 shows the analysis result of Example 5 at a magnification of 5000, FIG. 58 shows the analysis result of the Pt—Cu region at a magnification of 50000, and FIG. 59 shows the analysis result of the first W-Pt—Cu region at a magnification of 50000. FIG. 60 shows the analysis result of the Pt--W region at a magnification of 50,000, and FIG. 61 shows the analysis result of the boundary between the second W--Pt--Cu region and the W-based member at a magnification of 50,000. 57 to 61, (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. be. Further, for Example 5, a line segment X5 having a length of 20 μm is drawn from the lower side (W-based member side) to the upper side (Pt—Cu region side) in FIG. Changes in the concentration distribution of each element of Cu were investigated. The results are shown in FIG. The 0 μm position on the horizontal axis of FIG. 62 corresponds to the lower end of the line segment X5, and the 20 μm position corresponds to the upper end of the line segment X5. The vertical axis indicates the characteristic X-ray intensity of each element.

First, as shown in FIGS. 61 and 62, it was confirmed that the Pt element and the Cu element entered the grain boundaries of the W-based member also in Example 5. FIG. From this, it was confirmed that even when a Cu paste is used as a Cu source, a metal joined body having a W-based member in which a Pt—Cu phase exists in the grain boundaries can be manufactured. Further, as shown in FIGS. 57 to 61, in Example 5, an intermediate layer structure in which a Pt--Cu region, a first W--Pt--Cu region, a Pt--W region, and a second W--Pt--Cu region are laminated. layers were formed. The reason why the intermediate layer having such a layered structure was formed is that cracks in the Pt--W layer caused diffusion of Pt from the Pt--W layer from both the layer surface and the inside of the layer, as in Example 3 above. presumed to be because

6. Comparative example 1
(1) Preparation of Sample In Comparative Example 1, Cu paste was applied to the surface of the W-based member, and then dried and fired. Specifically, a Cu paste having the same composition as in Example 4 was applied to the surface of a W-based member having the same dimensions as in Example 1. Then, drying treatment was performed at 120° C. for 30 minutes to dry the Cu paste, and then heat treatment was performed in the air at 400° C. for 1 hour. After that, 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.

(2) Sample Analysis The sample of Comparative Example 1 was subjected to SEM observation and EDX analysis under the same conditions as in Example 1. FIG. 63 shows the analysis result of Comparative Example 1 at a magnification of 250, FIG. 64 shows the analysis result at a magnification of 1000, FIG. 65 shows the analysis result at a magnification of 5000, and FIG. show. 63 to 66, (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. Element map. As a result of these analyses, in Comparative Example 1, a phenomenon in which the Cu element or the like entered the grain boundaries of the W-based member was not confirmed (see, for example, FIG. 66(c)). Also, an intermediate layer containing an alloy material in which W and Cu are mixed was not formed. That is, even if Cu and W are brought into contact with each other in the absence of Pt (a state in which a W—Pt alloy is not formed) and the firing treatment is performed, the W-based member in which the Cu element or the like enters the grain boundaries Also, it was found that an intermediate layer in which W and Cu are mixed is not generated. In the sample of Comparative Example 1, the interface between the W-based member and the Cu layer was easily peeled off by an external force.

7. Comparative example 2
(1) Preparation of Sample In Comparative Example 2, a Pt paste was applied to the surface of a plate-shaped W-based member, followed by drying and firing. Specifically, a Pt paste having the same composition as in Example 1 was applied to the surface of a W-based member having the same dimensions as in Example 1. Then, after the Pt paste was dried by drying treatment at 120° C. for 30 minutes, heat treatment was performed in the air at 160° C. for 0.5 hour. After that, a firing process 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 joined body was obtained in which a layer containing platinum (Pt) was formed on the surface of the W-based member.

(2) Sample Analysis The sample of Comparative Example 2 was subjected to SEM observation and EDX analysis under the same conditions as in Example 1. FIG. 67 shows the analysis result of Comparative Example 2 at a magnification of 5000 times. In addition, (a) of FIG. 67 is a cross-sectional SEM image, (c) is an elemental map of W, and (d) is an elemental map of Pt. As a result of these analyses, an alloy containing Pt and W (Pt—W alloy) was formed on the surface of the W-based member by firing with the Pt source and W source in contact as in Comparative Example 2. It was confirmed that

8. Comparative example 3
(1) Preparation of Samples In Comparative Example 3, a Pt—Cu paste was applied to the surface of a plate-shaped W-based member, followed by drying and firing. Specifically, a Pt—Cu paste having the same composition as in Example 5 was applied to the surface of a W-based member having the same dimensions as in Example 1. Then, after performing a drying treatment at 120 ° C. for 30 minutes to dry the paste, performing a first heat treatment at 160 ° C. for 0.5 hours in the air, and then in N ₂ gas containing 3% H ₂ gas , the second heat treatment was performed with a temperature increase rate of 10° C./min, a maximum heating temperature of 400° C., and a heating time of 1 hour. Then, a baking treatment was performed with a temperature increase rate of 5° C./min, a maximum baking temperature of 1000° C., and a baking time of 30 minutes.

(2) Sample Analysis The sample of Comparative Example 3 was subjected to SEM observation and EDX analysis under the same conditions as in Example 1. FIG. 68 shows the analysis result of Comparative Example 3 at a magnification of 5000, and FIG. 69 shows the analysis result at a magnification of 50000. As a result of these analyses, when the Pt source and the Cu source were mixed and fired as in Comparative Example 3, although the Pt source and the Cu source were present on the surface of the W-based member, A W-based member containing the Pt element and the Cu element was not formed. Furthermore, a Pt--Cu alloy was formed on the surface of the W-based member, but this Pt--Cu alloy was not properly joined to the W-based member. The reason for such a result is presumed as follows. In Comparative Example 3, the reaction between the mixed Pt source and Cu source occurred preferentially, and no Pt—W alloy was produced. Since the Pt—Cu alloy produced by the reaction between the Pt source and the Cu source has low reactivity with the W-based member, it did not move (diffusion) into the grain boundaries of the W-based member. . From this, in order to form a W-based member having a Pt—Cu phase at the grain boundary, a Pt—W alloy is formed on the surface of the W-based member, and then a Cu source is brought into contact with the Pt—W alloy. It was found that it is better to perform the firing treatment at the same time.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

10 W-based member 12 Crystal grain 14 Pt-Cu phase 15 W-rich layer 16 Pt-W phase 20 Intermediate layer 22 W phase 24 Pt-Cu phase 25 Pt-W layer 100 Metal bonded body 200 Cu-based member

Claims (8)

a tungsten-based member containing tungsten (W);
Bonded to the surface of the tungsten-based member and comprising at least an intermediate layer containing platinum (Pt) and copper (Cu),
A metal joined body, wherein a Pt--Cu phase containing platinum (Pt) and copper (Cu) is present at grain boundaries of the tungsten-based member. 2. The metal bonded body according to claim 1, wherein said Pt--Cu phase exists in a region within 10 μm from the interface between said tungsten-based member and said intermediate layer toward the inside of said tungsten-based member. 3. The metal joined body according to claim 1, wherein said tungsten-based member is one selected from the group consisting of tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, and tungsten composite materials. 4. The metal joined body according to claim 3, wherein said tungsten composite material contains at least one element selected from the group consisting of copper (Cu), cobalt (Co), nickel (Ni) and molybdenum (Mo). The metal bonded body according to any one of claims 1 to 4, wherein the intermediate layer contains a copper alloy having a melting point lower than that of copper (Cu). 6. The metal bonded body according to claim 5, wherein said copper alloy having a melting point lower than that of copper (Cu) is an alloy of copper (Cu) and gold (Au). The intermediate layer comprises a W--Pt--Cu alloy in which a W phase containing tungsten (W) as a main component and a Pt--Cu phase containing platinum (Pt) and copper (Cu) are mixed. 7. The metal bonded body according to any one of 6. 8. The metal joined body according to claim 7, wherein said W--Pt--Cu alloy is constituted by a plurality of said W phases existing in said matrix consisting of said Pt--Cu phases.

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