Manufacturing method for alloy material and usage thereof

Abstract

To provide a novel technique that can provide a robust and reliable junction between a tungsten component and other metallic components.SOLUTION: A manufacturing method disclosed herein prepares an oxidation contact body where a W source containing the tungsten (W) element contacts a Cu source containing the copper (Cu) element, and W and Cu are oxidized at the boundary between the W source and the Cu source, then conducts calcination processing for the oxidation contact body under a reduction atmosphere. By this, a W- Cu alloy that is an alloy material where the W element and the Cu element are mutually diffused can be produced. Using the W- Cu alloy enables robust joining of the tungsten component with other metallic components.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing an alloy material and various members obtained by the method. [Background technology]

[0002] Tungsten members containing tungsten (W) (hereinafter also referred to as "W members") have the characteristics of a high melting point and a low thermal expansion coefficient, and are highly reliable in high-temperature environments. For this reason, W members are used in ultra-high-temperature parts exposed to high-temperature environments, such as divertors, accelerators, plasma discharge devices, high-temperature furnaces, and thin-film formation devices. On the other hand, tungsten is a rare and expensive metal, and is difficult to process. For this reason, metal joints in which W members are joined to other metal members are widely used. One example of a joint target for such W members is a member made of copper (Cu) (hereinafter also referred to as "Cu member").

[0003] However, according to the inorganic materials database (AtomWork) by the National Institute for Materials Science and others, it is said that no alloy is formed between W and Cu members due to mutual diffusion of metal elements. In other words, it is considered that a joining method of forming an alloy at the boundary between two metal members to form a strong joint cannot be used in joining W and Cu members, and joining methods other than alloy formation are used. One example of such other joining method is a method of heating the W and Cu members while applying strong pressure. In a joint made by such a method, it is considered that intermetallic bonding occurs in a very thin region at the joint interface between the W and Cu members. In addition, Patent Document 1 describes a method for manufacturing a dissimilar metal joint in which a W member and a Cu member are joined. In this manufacturing method, copper powder is interposed between a copper-containing bulk material (Cu member) and a tungsten-containing material (W member), and then a spark plasma sintering process is performed under a predetermined atmosphere. Patent Document 1 describes that the above-mentioned joining means (manufacturing method) makes it possible to manufacture a dissimilar metal joint having excellent joint strength and in which the occurrence of various problems is suppressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6563581 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, with the expansion of applications of W members, there is a demand for further improving the bonding strength and reliability of a metal bonded body in which a W member is bonded to another metal member (e.g., a Cu member). However, with the above-mentioned conventional bonding means, it is difficult to realize a strong and reliable bond that meets the recent demands. The present invention has been made to solve the above-mentioned problems, and its main purpose is to provide a new technology that realizes a strong and reliable bond between a tungsten member and another metal member. [Means for solving the problem]

[0006] As a result of various experiments and studies to solve the above-mentioned problems, the present inventors have discovered that when an oxidation contact body in which a W source and a Cu source containing Cu element are in contact with each other and W oxide and Cu oxide are present at the boundary between the W source and the Cu source is sintered in a reducing atmosphere, an alloy material (W-Cu alloy) in which W element and Cu element, which were thought not to be mutually diffused, are mutually diffused is surprisingly produced.The present inventors then considered that by using this W-Cu alloy, it is possible to join a W member and another metal member via the alloy material, and therefore it is possible to produce a metal joint that is strong and highly reliable.

[0007] The manufacturing method of the alloy material disclosed herein (hereinafter, simply referred to as the "manufacturing method") has been made based on the above findings. That is, the manufacturing method disclosed herein includes preparing an oxidized contact body in which a W source containing tungsten (W) element and a Cu source containing copper (Cu) element are in contact with each other, and in which W and Cu are oxidized at the boundary between the W source and the Cu source, and then subjecting the oxidized contact body to a sintering treatment in a reducing atmosphere. This makes it possible to form a W-Cu alloy in which the W element and the Cu element are mutually diffused. Then, by joining a W member and a Cu member via this W-Cu alloy, a strong and highly reliable metal joint can be produced.

[0008] In one embodiment of the manufacturing method disclosed herein, the W source is a solid metal member (W member) containing W element. By using the W member as the W source in this manner, a W-Cu alloy can be generated on the surface of the W member. The metal laminate in which the W-Cu alloy is formed on the surface of the W member in this manner can be suitably used when producing a metal bonded body in which the W member is bonded to another metal member.

[0009] In one embodiment of the manufacturing method disclosed herein, the W source comprises at least one selected from the group consisting of tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, copper-tungsten composite material, and silver-tungsten composite material. By using the above-mentioned W-based material as the W source, the W-Cu alloy can be appropriately formed.

[0010] In one embodiment of the manufacturing method disclosed herein, the Cu source is a Cu powder substantially composed of copper particles containing copper element. By using such a powder Cu source, interdiffusion between W element and Cu element is easily caused, so that the manufacturing efficiency of the W-Cu alloy can be improved.

[0011] In the above embodiment using Cu powder, the Cu powder preferably has an average particle size of 10 nm to 5000 nm based on SEM observation. By using such a very small amount of Cu powder, the interdiffusion between W element and Cu element occurs more easily, so that the W-Cu alloy can be produced more efficiently.

[0012] In one embodiment of the manufacturing method disclosed herein, the Cu source is a Cu paste in which Cu powder is dispersed in a specific solvent. This facilitates contact between the W source and the Cu source, further improving the manufacturing efficiency of the W-Cu alloy. In addition, when the W source is a W material, it is possible to prevent voids from occurring between the W-Cu alloy and the W material after production.

[0013] In one embodiment of the manufacturing method disclosed herein, an oxidized contact body is prepared by performing an oxidation treatment on a contact body in which a W source and a Cu source are in contact with each other. This makes it possible to easily obtain an oxidized contact body. However, the manufacturing method disclosed herein is not limited to this embodiment, and a W source and a Cu source that are individually oxidized may be brought into contact with each other to be used as the oxidized contact body.

[0014] In the embodiment in which the oxidation treatment is carried out, after the oxidation treatment and before the firing treatment, copper oxide is present at least in a region of 5 nm or more from the surface of the Cu source in contact with the W source. By carrying out the oxidation treatment in this way so that copper oxide is present at a predetermined thickness from the surface of the Cu source, it is possible to more appropriately generate a W-Cu alloy having a certain thickness or more (typically 5 nm or more).

[0015] In the embodiment in which the oxidation treatment is carried out, tungsten oxide is present at least in a region of 5 nm or more from the surface of the W source in contact with the Cu source after the oxidation treatment and before the firing treatment is carried out. In this way, by carrying out the oxidation treatment so that tungsten oxide is present at a predetermined thickness from the surface of the W source, it is possible to more appropriately generate a W-Cu alloy having a certain thickness or more (typically 5 nm or more).

[0016] In the embodiment in which the oxidation treatment is carried out, the contact body is heated in an oxidizing atmosphere in the oxidation treatment, whereby the W source and the Cu source can be sufficiently oxidized in a short time, and the W-Cu alloy can be efficiently produced.

[0017] In the embodiment in which the oxidation treatment is carried out, the heating temperature in the oxidation treatment is preferably 50° C. or higher and 200° C. or lower. By setting the heating temperature in the oxidation treatment to 50° C. or higher, the W source and the Cu source can be sufficiently oxidized in a shorter time. On the other hand, by setting the heating temperature in the oxidation treatment to 200° C. or lower, sintering of the W source and the Cu source during the oxidation treatment can be reliably prevented, and excessive oxidation of the Cu source can be prevented.

[0018] In the embodiment in which the oxidation treatment is carried out, the heating time in the oxidation treatment is preferably 0.5 hours or more, which allows the W source and the Cu source to be sufficiently oxidized, and therefore allows the W-Cu alloy to be appropriately produced.

[0019] In one embodiment of the manufacturing method disclosed herein, the firing process is carried out in an atmosphere filled with a neutral gas or a mixed gas of an inert gas and a reducing gas. By mixing a neutral gas (or an inert gas) in this way to reduce the concentration of the reducing gas, copper oxide and the like are prevented from being reduced in a low-temperature environment, and the oxidation state can be maintained until the temperature is raised to a high-temperature environment, thereby improving the production efficiency of the W-Cu alloy.

[0020] In addition, as described above, when the firing process is performed in an atmosphere filled with a mixed gas containing a reducing gas, the concentration of the reducing gas in the mixed gas is preferably 1% to 5%. By using a mixed gas with a very low reducing gas concentration in this way, the production efficiency of the W-Cu alloy can be more suitably improved. In addition, the reducing gas used at this time is preferably hydrogen gas.

[0021] In one embodiment of the manufacturing method disclosed herein, the heating temperature in the firing treatment is 500° C. or higher and 1100° C. or lower. By setting the heating temperature in the firing treatment to 500° C. or higher, the mutual diffusion of W element and Cu element can be promoted, and the manufacturing efficiency of the W-Cu alloy can be improved. On the other hand, by setting the heating temperature in the firing treatment to 1100° C. or lower, the W source and Cu source can be prevented from melting.

[0022] In one embodiment of the manufacturing method disclosed herein, the heating time in the firing treatment is 0.1 hours or more, which allows sufficient interdiffusion between W and Cu elements to occur and allows the W-Cu alloy to be properly manufactured.

[0023] In addition, as another aspect of the technology disclosed herein, there is provided an alloy material manufactured by the above-mentioned manufacturing method. This alloy material is a W-Cu alloy material containing, as a main component, a W-Cu alloy in which copper (Cu) elements and tungsten (W) elements are mutually dispersed. And, according to the above-mentioned manufacturing method, a W-Cu alloy material having a thickness of 5 nm or more can be manufactured. Such a W-Cu alloy material having a sufficient thickness is suitable as a joining material for joining a W member to another metal member.

[0024] Further, another aspect of the technology disclosed herein is a metal laminate having a W-Cu alloy layer. Such a metal laminate includes a W member containing tungsten (W) elements, and a W-Cu alloy layer formed on the surface of the W member and containing, as a main component, a W-Cu alloy in which copper (Cu) elements and tungsten (W) elements are dispersed in each other. In the metal laminate disclosed herein, the thickness of the W-Cu alloy layer is 5 nm or more. By using a metal laminate having such a configuration, the W member and another metal member can be joined via a W-Cu alloy layer of sufficient thickness, and a strong and highly reliable metal joint can be produced.

[0025] In addition, as another aspect of the technology disclosed herein, a metal joined body is provided. The metal joined body includes the above-mentioned metal laminate and a joining object joined to the surface of the W-Cu alloy layer of the metal laminate. In the metal joined body, the W member and the other metal member are joined via the W-Cu alloy layer, so that the metal joined body is strong and has high reliability.

[0026] In one embodiment of the joined body disclosed herein, the objects to be joined are Cu members containing copper (Cu). Moreover, the Cu members are preferably at least one selected from the group consisting of tough pitch copper, oxygen-free copper, copper alloys, and copper powder sintered bodies. The W-Cu alloy obtained by the technique disclosed herein can be joined particularly well with Cu members. In other words, the technique disclosed herein can be particularly suitably used for manufacturing a metal joined body in which a W member and a Cu member are joined. [Brief description of the drawings]

[0027] [Figure 1] (a) is a cross-sectional SEM image (100,000x) of sample 1, and (b) and (c) are elemental maps of Cu and W, respectively, based on EDX analysis. [Diagram 2] (a) is a cross-sectional SEM image (100,000x) of sample 2, and (b) and (c) are elemental maps of Cu and W, respectively, based on EDX analysis. [Diagram 3] 1 is an SEM photograph of Sample 2. [Figure 4] (a) is a cross-sectional SEM image (50,000x) of sample 3, and (b) to (d) are elemental maps of O, Cu, and W, respectively, based on EDX analysis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] An embodiment of the technology disclosed herein will be described below. Matters other than those specifically mentioned in this specification and necessary for implementing the technology disclosed herein can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the relevant field. In this specification, "A to B (A and B are numerical values)" means "A or more and B or less."

[0029] 1. Manufacturing method of alloy materials First, the manufacturing method of the alloy material disclosed herein is described. In the manufacturing method disclosed herein, the oxidation contact body is subjected to a sintering treatment under a reducing atmosphere. This makes it possible to manufacture an alloy material (W-Cu alloy) in which W and Cu elements are mutually diffused. Each step in the manufacturing method is specifically described below.

[0030] (1) Preparation of the oxidation contact In the production method disclosed herein, first, an oxidized contact body is prepared. In this specification, the term "oxidized contact body" refers to a contact body in which a W source and a Cu source are in contact with each other, and in which W oxide and Cu oxide are present at the boundary between the W source and the Cu source.

[0031] (a) W source The W source may be a material containing tungsten (W) element, and its form and specific components are not particularly limited. For example, the form of the W source may be a solid metal member (W member) containing W element, or may be W powder substantially composed of tungsten particles containing W element. The W source may also be a W paste in which W powder is dispersed in a predetermined solvent. Among these forms, it is preferable to use a W member, which is a solid metal member, as the W source. This allows a metal laminate in which a W-Cu alloy is formed on the surface of the W member to be manufactured. This allows the procedure for joining the W member to another metal member (joining target) to be simplified. In addition, when W powder is used as the W source, the average particle diameter of the W powder is preferably 10 μm or less, more preferably 5 μm or less, further preferably 3 μm or less, and particularly preferably 1 μm or less. By using such fine W powder as the W source, it is possible to promote the mutual diffusion of the W element and the Cu element in the reduction firing treatment described later. In addition, in consideration of the ease of handling of the W source when preparing the oxidation contact body, the average particle diameter of the W powder is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 30 nm or more, and particularly preferably 50 nm or more. In this specification, the "average particle diameter" is the arithmetic mean value of the equivalent circle diameter of the area of ​​200 particles measured based on SEM observation or TEM observation. In addition, when a W paste is used as a W source, the components other than the W powder (solvent, binder, dispersant, etc.) are not particularly limited, and components that can be added to a general metal paste can be used without particular limitation.

[0032] Examples of the components of the W source include tungsten, tungsten nitride, tungsten carbide, and tungsten carbonitride. From the viewpoint of preventing poor production of the W-Cu alloy due to a shortage of W element, the W source preferably contains W element as a main component. Here, "containing W element as a main component" means that elements other than W element are not intentionally contained. Therefore, when unavoidable impurities (metal elements other than W element) derived from raw materials or manufacturing processes are contained in the W source, it is included in the concept of "containing W element as a main component" in this specification. For example, if the number of atoms of W element is 75 at% or more when the total number of metal elements constituting the W source is 100 at%, it can be said that "containing W element as a main component". From the viewpoint of more appropriately causing the diffusion of W element in the firing process, the number of atoms of W element in the W source is preferably 77.5 at% or more, more preferably 80 at% or more, even more preferably 82.5 at% or more, and particularly preferably 85 at% or more. The upper limit of the number of atoms of the W element in the W source is not particularly limited, and may be 99.5 at% or less, 97.5 at% or less, 95 at% or less, 92.5 at% or less, or 90 at% or less. The W source is not limited to the above-mentioned form of "containing W element as a main component". For example, the W source may be composed of a composite material obtained by combining a W-based material with other materials. For example, the W source may contain copper (Cu), silver (Ag), molybdenum (Mo), iron (Fe), cobalt (Co), nickel (Ni), gold (Au), thorium (Th), etc. Examples of this type of composite material include a copper-tungsten composite material and a silver-tungsten composite material. The W source may also be composed of a composite material obtained by mixing a W-based material with a ceramic. Examples of ceramics that may be contained in the W source include high-melting point ceramics such as thoria (ThO2) and yttria (Y2O3).

[0033] (b) Cu source As with the above-mentioned W source, the Cu source may be a material containing copper (Cu) element, and its form and specific components are not particularly limited. For example, the Cu source may be a Cu powder substantially composed of Cu particles containing Cu element. By using a fine Cu source such as Cu powder, diffusion of Cu element is likely to occur in the reduction firing treatment described later. From the viewpoint of more favorable diffusion of Cu element, the average particle size of the Cu powder is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, and particularly preferably 2 μm or less. In addition, if the particle size of the Cu powder becomes too small, the handling of the Cu source when preparing the oxidation contact body tends to become difficult. From this viewpoint, the average particle size of the Cu powder is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 30 nm or more, and particularly preferably 50 nm or more. In addition, the Cu source may be a Cu paste in which the above-mentioned Cu powder is dispersed in a predetermined solvent. This makes it easier for the W source and the Cu source to come into contact with each other, further improving the efficiency of producing the W-Cu alloy. In particular, when the W source is a solid metal member (W member), by using a Cu paste as the Cu source, it is possible to prevent the occurrence of voids between the W-Cu alloy and the W member after production. In addition, when using a Cu paste, the components other than the Cu powder (solvent, binder, dispersant, etc.) are not particularly limited, and components that can be added to general metal pastes can be used without particular limitations. In addition, the Cu source is not limited to the above-mentioned Cu powder, and may be a solid metal member (Cu member) containing Cu elements. By using this Cu member as the Cu source, a metal laminate in which a W-Cu alloy layer is formed on the surface of the Cu member can be produced.

[0034] The Cu source used in this process may be a material containing Cu element, and the components are not particularly limited. Specifically, metal elements that can be mixed with the Cu source include gold (Au), nickel (Ni), aluminum (Al), tin (Sn), zinc (Zn), silica (Si), iron (Fe), manganese (Mn), cobalt (Co), and beryllium (Be). From the viewpoint of appropriately causing diffusion of Cu element in the reduction firing process, it is preferable that the Cu source contains Cu element as a main component. Here, "containing Cu element as a main component" means that elements other than Cu element are not intentionally contained. Therefore, when unavoidable impurities (metal elements other than Cu element) derived from raw materials, manufacturing process, etc. are contained in the Cu source, it is included in the concept of "containing Cu element as a main component" in this specification. For example, when the total number of metal elements constituting the Cu source is 100 at%, if the atomic number of Cu element is 75 at% or more, it can be said that "containing Cu element as a main component". From the viewpoint of more appropriately diffusing the Cu element in the firing treatment, the atomic number of the Cu element in the Cu source is preferably 77.5 at% or more, more preferably 80 at% or more, and particularly preferably 82.5 at% or more. The upper limit of the atomic number of the Cu element in the Cu source is not particularly limited, and may be 99.5 at% or less, 97.5 at% or less, 95 at% or less, 92.5 at% or less, or 90 at% or less.

[0035] (c) Preparation of the oxidation contact In the manufacturing method disclosed herein, an oxidized contact body is prepared using the above-mentioned W source and Cu source. As an example of a means for obtaining such an oxidized contact body, a contact body in which the W source and the Cu source are in contact with each other is prepared in advance, and the contact body is subjected to an oxidation treatment. The specific procedure of such a means will be described below.

[0036] (c-1) Preparation of contact body As described above, a contact body in which the W source and the Cu source are in contact with each other is prepared. The form of the contact body varies depending on the form of each of the W source and the Cu source, and does not limit the technology disclosed herein. For example, when both the W source and the Cu source are solid metal members, the contact body can be prepared by bringing each metal member (W member and Cu member) into close contact with each other. When both the W source and the Cu source are powder materials, a mixed powder in which each powder material (W powder and Cu powder) is mixed can be prepared as the contact body. As described above, when a W member is prepared as the W source and a Cu paste is prepared as the Cu source, the contact body can be prepared by applying the Cu paste to the surface of the W member. By bringing the W source and the Cu source into contact with each other by applying the paste in this way, the W source and the Cu source can be easily brought into close contact with each other, and therefore, it is possible to prevent the occurrence of voids between the W-Cu alloy and the W member after the reduction firing treatment. In addition, when a W material is prepared as the W source and Cu powder is prepared as the Cu source, a contact body can be prepared by bringing a molded body in which the Cu powder is filled into a frame into contact with the W material.

[0037] (c-2) Oxidation treatment Next, the above-mentioned contact body is subjected to an oxidation treatment. As a result, each of the W source and the Cu source is oxidized, and an oxidized contact body in which W oxide and Cu oxide exist at the boundary between the W source and the Cu source is generated. The specific procedure of the oxidation treatment is not particularly limited, and various conventionally known means can be adopted without particular limitation. For example, in the oxidation treatment, the contact body may be heated in an oxidizing atmosphere. By performing such an oxidation treatment accompanied by heating, the W source and the Cu source can be sufficiently oxidized in a short time, which contributes to improving the production efficiency of the oxidized contact body (i.e., the production efficiency of the W-Cu alloy). In addition, it is preferable that the Cu source after carrying out this process has copper oxide present at least in a region of 5 nm or more (more preferably 20 nm or more, even more preferably 50 nm or more, particularly preferably 100 nm or more) from the surface in contact with the W source. By carrying out an oxidation treatment that sufficiently oxidizes the Cu source in this way, a W-Cu alloy having a thickness of 5 nm or more can be more appropriately generated. On the other hand, after carrying out this step, it is preferable that tungsten oxide is present in at least a region of 5 nm or more (more preferably 7 nm or more, even more preferably 10 nm or more, and particularly preferably 15 nm or more) from the surface in contact with the Cu source. By carrying out an oxidation treatment that sufficiently oxidizes the W source in this way, it is possible to more appropriately generate a W-Cu alloy having a thickness of 5 nm or more.

[0038] In addition, when performing oxidation treatment involving heating, in order to generate an oxide of a predetermined thickness as described above, the heating temperature is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 80°C or higher, and particularly preferably 100°C or higher. This appropriately promotes the oxidation of the W source and the Cu source to generate an oxide of sufficient thickness. On the other hand, from the viewpoint of preventing the W source and the Cu source from sintering during the oxidation treatment and preventing excessive oxidation of the Cu source, the upper limit of the heating temperature in the oxidation treatment is preferably 200°C or lower, more preferably 180°C or lower, even more preferably 160°C or lower, and particularly preferably 140°C or lower. By performing the oxidation treatment under such conditions, monovalent copper oxide (copper(I) oxide) is generated on the surface of the Cu source after the treatment. Furthermore, it is preferable to adjust the heating time in the oxidation treatment from the viewpoint of sufficiently oxidizing the W source and the Cu source. As an example, the heating time in the oxidation treatment is preferably 0.5 hours or more, more preferably 1 hour or more, even more preferably 1.5 hours or more, and particularly preferably 2 hours or more. On the other hand, the upper limit of the heating time is not particularly limited, and may be 24 hours or less, or may be 21 hours or less. In consideration of the improvement of production efficiency by shortening the oxidation treatment, the upper limit of the heating time in the oxidation treatment is preferably 10 hours or less, more preferably 7.5 hours or less, and particularly preferably 5 hours or less. However, these heating times in the oxidation treatment do not limit the technology disclosed herein, and can be changed as appropriate. For example, when the heating temperature is increased, the heating time required to sufficiently oxidize the W source and the Cu source can be shortened. In this specification, the "heating temperature" refers to the maximum temperature in the heat treatment, and the "heating time" refers to the time to maintain the maximum temperature. As described above, the specific procedure of the oxidation treatment is not particularly limited as long as the W source and the Cu source can be sufficiently oxidized. For example, if a contact body in which the W source and the Cu source are in contact with each other is left in an oxygen atmosphere for a long period of time (for example, 10 days or more), an oxidized contact body in which the W source and the Cu source are sufficiently oxidized can be obtained without performing a heat treatment.

[0039] (c-3) Other means The means for obtaining the oxidized contact body is not limited to the above means, and various means can be adopted. For example, the surfaces of the W source and the Cu source may be individually oxidized, and then the oxidized surfaces may be brought into contact with each other. Even when the oxidized contact body prepared by such a means is used, the W-Cu alloy disclosed herein can be produced.

[0040] (2) Reduction firing treatment Next, in the manufacturing method disclosed herein, the oxidized contact body prepared as described above is subjected to a calcination treatment under a reducing atmosphere. In this reduction calcination treatment, mutual diffusion between W and Cu elements occurs, and a W-Cu alloy is generated. As described above, this W-Cu alloy is an alloy material that has not been considered to be generated in the past. Although it is not intended to limit the technology disclosed herein, the following hypothesis is considered as a generation mechanism of such an alloy material. In the manufacturing method disclosed herein, an oxidized contact body in which W oxide and Cu oxide are generated at the interface between the W source and the Cu source is used. Then, when this oxidized contact body is subjected to a reduction calcination treatment, a tungsten copper composite oxide (W-Cu composite oxide) in which the W oxide and the Cu oxide are mutually diffused is generated at the beginning of the calcination treatment. When the reduction calcination treatment is continued thereafter, the reduction of the W-Cu composite oxide progresses, and a W-Cu alloy is generated. In addition, the following is also considered as another example of a hypothesis of the generation mechanism of the W-Cu alloy. When the oxidized Cu source (copper oxide) is subjected to a reduction firing process, the Cu element is activated during the reduction reaction, which may have facilitated the diffusion of the Cu element into the W source, resulting in the formation of a W-Cu alloy.

[0041] The heating temperature in the reduction 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 can improve the production efficiency of the W-Cu alloy. On the other hand, if the heating temperature in the reduction firing process is too high, the W source and the Cu source may melt, and the W-Cu alloy may not be produced. From this viewpoint, the upper limit of the heating 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. In addition, the heating time in the reduction firing process is preferably 0.5 hours or more, and more preferably 1 hour or more. This allows the W-Cu alloy to be appropriately produced. On the other hand, in consideration of the improvement of production efficiency by shortening the reduction firing process, the upper limit of the heating time in this process is preferably 5 hours or less, more preferably 4 hours or less, and particularly preferably 3 hours or less.

[0042] In addition, the atmosphere during the firing is not particularly limited as long as it is adjusted to a reducing atmosphere. Examples of the reducing gas used to make the firing atmosphere a reducing atmosphere include hydrogen (H2) gas and hydrocarbon (CH4, C3H8, etc.) gas. In addition, from the viewpoint of more appropriately generating the W-Cu alloy, it is preferable to perform the firing process in an atmosphere filled with a neutral gas or a mixed gas of an inert gas and a reducing gas. When the concentration of the reducing gas is reduced by mixing a neutral gas (or an inert gas) in this way, the temperature at which the reduction reaction of copper oxide, tungsten oxide, and copper-tungsten composite oxide is completed increases. This suppresses the reduction of copper oxide and the like in a low-temperature environment (about 200°C) and returns to copper, and the oxidized state can be maintained until the temperature is raised to a high-temperature environment, so that the interdiffusion of W element and Cu element occurs easily along with the reduction reaction, and the generation efficiency of the W-Cu alloy is improved. In addition, an example of the inert gas mixed with the above-mentioned reducing gas includes argon (Ar) gas. In addition, an example of the neutral gas includes nitrogen (N2) gas and ammonia. The concentration of the reducing gas (e.g., hydrogen (H2) gas) in the mixed gas is preferably 20% or less, more preferably 1% to 5%, and may be set to, for example, 3%. By using a mixed gas with a very low reducing gas concentration in this way, the oxidation state can be maintained until the temperature is raised to a high-temperature environment of 500°C or more, and a reduction reaction can occur in the high-temperature environment, so that the production efficiency of the W-Cu alloy can be more preferably improved.

[0043] 2.Alloy material Next, an alloy material manufactured by the manufacturing method disclosed herein will be described. According to the manufacturing method disclosed herein, an alloy material (W-Cu alloy material) containing a W-Cu alloy in which Cu elements and W elements are mutually dispersed as a main component and having a thickness of 5 nm or more is manufactured. Then, by using the W-Cu alloy material having a thickness of 5 nm or more, a W member and another metal member (for example, a Cu member) can be firmly joined. Specifically, even in the conventional technology for directly joining the above-mentioned Cu member and W member, diffusion of the W element and the Cu element may occur in a very narrow region of less than 1 nm (typically about several atoms) at the boundary between the Cu member and the W member. However, even if diffusion of the W element and the Cu element occurs in such a very narrow region, the bonding strength between the W member and the Cu member is not dramatically improved. In contrast, according to the manufacturing method disclosed herein, a W-Cu alloy material having a thickness of 5 nm or more can be easily manufactured. That is, according to the technology disclosed herein, an alloy material capable of improving the bonding strength between the Cu member and the W member can be provided.

[0044] As described above, the W-Cu alloy material disclosed herein contains a W-Cu alloy as a main component. Here, "containing a W-Cu alloy as a main component" means that elements other than W and Cu are not intentionally included. Therefore, the "W-Cu alloy material" in this specification includes metal materials that contain a trace amount of unavoidable impurities derived from raw materials, manufacturing processes, etc., in addition to W and Cu elements. For example, the W-Cu alloy material disclosed herein includes metal materials in which the total atomic number of W and Cu elements is 75 at% or more when the total number of constituent elements is 100 at%. From the viewpoint of more sufficiently ensuring the bondability with W and Cu members, the total atomic number of W and Cu elements in the W-Cu alloy member is preferably 80 at% or more, more preferably 82.5 at% or more, and particularly preferably 85 at% or more. The upper limit of the total atomic number of W and Cu elements in the W-Cu alloy material is not particularly limited, and may be 100 at% or less, 99.5 at% or less, 99 at% or less, 98 at% or less, or 97 at% or less. Elements (unavoidable impurities) that may be contained in the W-Cu alloy material include O, Cu, Pt, Mo, Fe, Pd, Ir, Au, Co, Ni, Zn, Al, Sn, Pb, Mn, Ag, and Th.

[0045] The content ratio of W element and Cu element in the W-Cu alloy is not particularly limited. As an example, when the total number of atoms of W element and Cu element in the W-Cu alloy is 100 at%, the number of W element atoms is preferably 5 at% to 50 at%. As the number of W element atoms increases, the bondability with the W member tends to improve. From this viewpoint, the number of W element atoms is preferably 10 at% or more, more preferably 15 at% or more, and particularly preferably 20 at% or more. On the other hand, as the number of W element atoms decreases, the number of Cu element atoms relatively increases, so that the bondability with the Cu member tends to improve. From this viewpoint, the number of W element atoms is preferably 40 at% or less, more preferably 35 at% or less, and particularly preferably 30 at% or less.

[0046] Also, as described above, from the viewpoint of firmly joining the W member and other metal members, the thickness of the W-Cu alloy material is required to be 5 nm or more. From the viewpoint of further improving the joining strength between the W member and other metal members, the thickness of the W-Cu alloy material is preferably 50 nm or more, preferably 100 nm or more, preferably 150 nm or more, and preferably 200 nm or more. The upper limit of the thickness of the W-Cu alloy member is not particularly limited, and may be 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, or 500 nm or less.

[0047] 3. Metal laminates and metal joints The technique disclosed herein can also produce members containing a W-Cu alloy (metal laminate and metal joint body), each of which will be described in detail below.

[0048] (1) Metal laminate According to the technology disclosed herein, a metal laminate is provided in which a W-Cu alloy layer is formed on the surface of a W member. Such a metal laminate can be easily obtained, for example, as described above, by preparing a contact body by applying Cu paste to the surface of a W member in the preparation of the contact body. This metal laminate can also be prepared by welding an already produced W-Cu alloy material to the surface of the W member. This metal laminate can be easily joined to other metal members by using the W-Cu alloy layer as the joining surface. That is, by using the metal laminate disclosed herein, a metal joined body in which a W member and another metal member are joined can be easily prepared. As described above, in order to sufficiently secure the joining strength between the W member and another metal member, the thickness of the W-Cu alloy layer of the metal laminate disclosed herein is set to 5 nm or more. The W member used in this metal laminate may be a solid metal member containing W element, and its shape and components are not particularly limited. For example, the W member of the metal laminate can be the same as the W member that can be used as the W source described above, so that a duplicated explanation will be omitted.

[0049] (2) Metal bonded body A metal joint is formed by joining another metal member (joining object) to the surface of the W-Cu alloy layer side of the metal laminate including the above-mentioned W member and W-Cu alloy. This metal joint can be easily obtained, for example, by preparing a contact body in which Cu paste is placed between the W member and the joining object in the preparation of the above-mentioned contact body. This metal joint can also be prepared by welding the joining object to the W-Cu alloy layer of the above-mentioned metal laminate.

[0050] In the technology disclosed herein, the object to be joined with the W member is not particularly limited, and conventionally known metal members can be used without any particular restrictions. For example, the object to be joined may be a metal member (dissimilar metal member) different from the W member. Specifically, by joining the W member and the dissimilar metal member via a W-Cu alloy, the W member and the dissimilar metal member can be joined firmly and with high reliability. The dissimilar metal member is not particularly limited as long as it is a metal member that can be joined with the W-Cu alloy. Examples of such dissimilar metal members include metal members containing copper (Cu), nickel (Ni), zinc (Zn), aluminum (Al), etc. Among the above-mentioned dissimilar metal members, a Cu member containing copper as a main component is particularly suitable for joining with the W-Cu alloy and is a relatively inexpensive metal member, so that it is suitable as a joining object. Specific examples of this Cu member include tough pitch copper, oxygen-free copper, copper alloy, and copper powder sintered body. In addition, the object to be joined with the W member in the technology disclosed herein is not limited to dissimilar metal members. In other words, the W-Cu alloy material disclosed herein can also be used to join W members together.

[0051] As described above, the technique disclosed herein can produce an alloy material (W-Cu alloy) containing W and Cu elements, which have been conventionally believed not to interdiffuse. Furthermore, by using a W-Cu alloy material having a thickness of 5 nm or more, a W member and another metal member can be firmly joined. That is, the technique disclosed herein can realize a strong and reliable joining between a tungsten member and another metal member, which can contribute to improving the performance of ultra-high temperature parts such as divertors, accelerators, plasma discharge devices, high-temperature furnaces, and thin film forming devices. The use of the W-Cu alloy disclosed herein is not limited to joining W members, and it can also be used as a barrier film, catalyst, etc. to protect the surface of a metal member (e.g., a W member).

[0052] [Test example] Test examples relating to the present invention will be described below, but these test examples are not intended to limit the present invention.

[0053] In this test, three types of metal joints (samples 1 to 3) were produced by joining a W member and a Cu member, and various analyses were performed on each of the metal joints.

[0054] (1) Sample 1 First, Cu paste was applied to the entire surface of one side of a Cu member (a tough pitch copper plate measuring 0.3 mm thick x 15 mm thick x 15 mm thick). A W member (a tungsten plate measuring 0.3 mm thick x 7.5 mm thick x 7.5 mm thick) was placed on the Cu paste and lightly pressed with a finger to create a contact body in which the W member and the Cu paste were in contact. The Cu paste used in this sample contains 90 wt% Cu powder with an average particle size of 1 μm. The materials other than the Cu powder are glass powder, a binder (ethyl cellulose resin), a dispersing agent, and a solvent.

[0055] Next, the above-mentioned contact body was subjected to a heat treatment of heating at 120°C for 4 hours in an oxidizing atmosphere to produce an oxidized contact body. At this time, when the Cu film after drying of the Cu paste was observed, it was slightly reddish. From this, it is understood that the Cu powder was oxidized by the above-mentioned heat treatment to produce red copper oxide (I). Then, the oxidized contact body was moved to a reducing atmosphere filled with N2-H2 (3%) gas, and a binder removal treatment (heating rate: 10°C / min, heating temperature: 400°C, heating time: 1 hour) was performed. Then, a firing treatment (heating rate: 5°C / min, maximum temperature: 1000°C, firing time: 30 minutes) was performed while maintaining the reducing atmosphere. Then, the sample after firing was cooled to room temperature to obtain Sample 1. Then, this Sample 1 was polished by ion milling, and SEM observation and EDX analysis were performed. The results are shown in Figure 1. In addition, in FIG. 1, (a) is a cross-sectional SEM image (100,000 times), (b) is an elemental map of Cu, and (c) is an elemental map of W.

[0056] As shown in FIG. 1, in Sample 1, it was confirmed that a W-Cu alloy was formed between the W member and the Cu member, in which W elements and Cu elements were mutually diffused. This shows that by performing a reduction and calcination treatment on an oxidation contact body in which W oxides and Cu oxides exist at the boundary between the W source and the Cu source, mutual diffusion between W elements and Cu elements, which was previously thought not to occur, occurs. In addition, the thickness of the W-Cu alloy observed in Sample 1 was about 230 nm. The metal joint between the W member and the Cu member, which were joined via a W-Cu alloy of such thickness, had very high strength.

[0057] (2) Sample 2 Here, sample 2 was prepared under the same conditions as sample 1, except that the time of the heat treatment before the reduction firing treatment was extended to 21 hours. Then, as a result of observing the surface on which the Cu paste was applied after the heat treatment, a Cu film with a stronger redness than that of sample 1 was formed. From this, it is understood that the Cu powder was oxidized by the heat treatment in this sample as well. Then, SEM observation and EDX analysis were performed on the prepared sample 2 under the same conditions as sample 1. The results are shown in Figure 2. Note that (a) in Figure 2 is a cross-sectional SEM image (100,000 times), (b) is an element map of Cu, and (c) is an element map of W. In addition, EDX analysis was performed on each point 1 to 3 in Figures 3(a) to (c), which are cross-sectional SEM images at 100,000 times, for sample 2, and the ratio of the number of W and Cu atoms (at%) was measured. The measurement results are shown in Table 1 below.

[0058] [Table 1]

[0059] As shown in Figures 2 to 3 and Table 1, in Sample 2, a W-Cu alloy was generated between the W member and the Cu member (for example, point 2 in Figure 3), in which W elements and Cu elements diffused into each other. This shows that a W-Cu alloy can be generated even when the oxidation treatment time is extended to 21 hours. In Sample 2, as in Sample 1, the thickness of the W-Cu alloy exceeded 5 nm, and the bonding strength was very high.

[0060] (3) Sample 3 Here, sample 3 was prepared under the same conditions as sample 1, except that the time of the heat treatment before the reduction firing treatment was shortened to 30 minutes. When the surface to which the Cu paste was applied was observed after the heat treatment, a red film like that of samples 1 and 2 was not formed. This indicates that the oxidation of the Cu powder in this sample was insufficient. SEM observation and EDX analysis were then carried out on the prepared sample 3 under the same conditions as sample 1. The results are shown in Figure 4. In Figure 4, (a) is a cross-sectional SEM image (50,000x), (b) is an elemental map of O, (c) is an elemental map of Cu, and (d) is an elemental map of W.

[0061] As shown in Fig. 3, in sample 3, the boundary between the Cu and W components is clearly confirmed, and it is understood that there is no mutual diffusion between the W and Cu elements. This shows that if the Cu and W components are not sufficiently oxidized before the reduction firing process, a W-Cu alloy is not produced. From the above experimental results, it is found that in order to produce a W-Cu alloy in which the W and Cu elements are mutually diffused, it is necessary to perform a firing process in a reducing atmosphere after performing an oxidation process in which the Cu source and the W source are oxidized.

[0062] 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 exemplified above.

Claims

1. A method for producing an alloy material includes preparing an oxidized contact body in which a W source containing tungsten (W) element and a Cu source containing copper (Cu) element are contacted with each other, and W and Cu are oxidized at the boundary between the W source and the Cu source, and then subjecting the oxidized contact body to a sintering treatment under a reducing atmosphere.

2. The method for producing an alloy material according to claim 1 , wherein the W source is a solid metal component containing W element.

3. 3. The method of claim 2, wherein the W source comprises at least one selected from the group consisting of tungsten, tungsten nitride, tungsten carbide, tungsten carbonitride, copper tungsten composite, and silver tungsten composite.

4. The method for producing an alloy material according to any one of claims 1 to 3, wherein the Cu source includes Cu powder substantially composed of copper particles containing elemental copper.

5. The method for producing an alloy material according to claim 4, wherein the Cu powder has an average particle size based on SEM observation of 10 nm to 5000 nm.

6. 6. The method for producing an alloy material according to claim 4, wherein the Cu source is a Cu paste obtained by dispersing the Cu powder in a predetermined solvent.

7. The method for producing an alloy material according to any one of claims 1 to 6, wherein the oxidized contact body is prepared by performing an oxidation treatment on a contact body in which the W source and the Cu source are in contact with each other.

8. 8. The method for producing an alloy material according to claim 7, wherein copper oxide is present at least in a region of 5 nm or more from a surface of the Cu source in contact with the W source after the oxidation treatment and before the firing treatment.

9. 9. The method for producing an alloy material according to claim 7, wherein after the oxidation treatment and before the firing treatment, tungsten oxide is present at least in a region of 5 nm or more from a surface of the W source in contact with the Cu source.

10. The method for producing an alloy material according to any one of claims 7 to 9, wherein in the oxidation treatment, the contact body is heated in an oxidizing atmosphere.

11. The method for producing an alloy material according to claim 10, wherein the heating temperature in the oxidation treatment is 50° C. or more and 200° C. or less.

12. The method for producing an alloy material according to claim 10 or 11, wherein the heating time in the oxidation treatment is 0.5 hours or more.

13. The method for producing an alloy material according to any one of claims 1 to 12, wherein the sintering treatment is carried out in an atmosphere filled with a neutral gas or a mixed gas of an inert gas and a reducing gas.

14. The method for producing an alloy material according to claim 13, wherein the concentration of the reducing gas in the mixed gas is 1% to 5%.

15. The method for producing an alloy material according to claim 13 or 14, wherein the reducing gas is hydrogen gas.

16. The method for producing an alloy material according to any one of claims 1 to 15, wherein the heating temperature in the sintering treatment is 500°C or higher and 1100°C or lower.

17. The method for producing an alloy material according to any one of claims 1 to 16, wherein a heating time in the firing treatment is 0.1 hours or more.

18. An alloy material containing, as a main component, a W-Cu alloy in which copper (Cu) elements and tungsten (W) elements are dispersed in each other, and having a thickness of 5 nm or more.

19. A W member containing tungsten (W) element; a W-Cu alloy layer formed on the surface of the W member and containing, as a main component, a W-Cu alloy in which copper (Cu) elements and tungsten (W) elements are dispersed; Equipped with The metal laminate, wherein the W-Cu alloy layer has a thickness of 5 nm or more.

20. The metal laminate according to claim 19 ; A joining object joined to the surface of the W—Cu alloy layer of the metal laminate. A metal joint comprising:

21. The metal joined body according to claim 20, wherein the joining objects are Cu members containing copper (Cu) element.

22. The metal joined body according to claim 21, wherein the Cu member is at least one selected from the group consisting of tough pitch copper, oxygen-free copper, a copper alloy, and a copper powder sintered body.

Images