WO2011155214A1

WO2011155214A1 - Bonding member and manufacturing method thereof

Info

Publication number: WO2011155214A1
Application number: PCT/JP2011/003298
Authority: WO
Inventors: 英樹山岸; 昭二餅川
Original assignee: ワシマイヤー株式会社; 富山県
Priority date: 2010-06-10
Filing date: 2011-06-10
Publication date: 2011-12-15
Also published as: JP5830727B2; JPWO2011155214A1

Abstract

[Problem] In order to provide a bonding member which is light weight and has a superior ability to bond a magnesium member and an aluminium member, and a manufacturing method for the bonding member which enables the simple, high productivity manufacture of said bonding member. [Solution] The present invention is a bonding member (100) provided with a magnesium member (1) comprising a magnesium alloy, an aluminium member (2) comprising an aluminium alloy, and an intermediate layer (3) formed between the magnesium member (1) and the aluminium member (2); wherein the intermediate layer (3) comprises an insert material selected from a group comprising Ni, Cu, and Ti, and the magnesium member (1), the aluminium member (2), and intermediate layer (3) are integrally bonded.

Description

CONNECTING MEMBER AND MANUFACTURING METHOD THEREOF

The present invention relates to a coupling member and a manufacturing method thereof, and more specifically, a coupling member that is lightweight and excellent in the joining property between a magnesium member and an aluminum member, and the coupling member can be easily manufactured, and the productivity is also improved. The present invention relates to a method for manufacturing an excellent coupling member.

In general, an aluminum alloy has excellent mechanical strength, whereas a magnesium alloy has a characteristic of being lightweight.
In recent years, there has been a demand for a coupling member having both of these characteristics.

For example, a magnesium-aluminum clad material in which a magnesium alloy is used as an inner core material and the surface layer of the magnesium alloy is directly coated with aluminum or an alloy thereof by extrusion is known (for example, see Patent Document 1).
Also, rolling, extruding, drawing, or compression processing is performed on one or a plurality of surfaces of the magnesium material or the magnesium alloy material so that the thickness is 0.1 to 10% of the vertical thickness of the magnesium material or the magnesium alloy material. An aluminum-coated magnesium alloy material coated with a pure aluminum material or an aluminum alloy material is known (see, for example, Patent Document 2).

As a method of directly joining an aluminum alloy and a magnesium alloy, the base material is pressed and adhered, and a solid phase is formed by a diffusion joining method using atomic diffusion under a temperature condition below the melting point of the base material or by frictional heat of a rotary tool. There is known a friction stir welding method (FSW) in which members are integrated in a state by plastic flow (for example, see Non-Patent Document 1).

JP-A-6-328270 JP 2003-181975 A

However, the magnesium-aluminum clad material described in Patent Document 1 and the aluminum-coated magnesium alloy material described in Patent Document 2 are both in a form in which the magnesium alloy is simply coated with an aluminum alloy. The tensile strength (hereinafter also referred to as “joinability”) of the joint portion with the above is not sufficient.

In the diffusion bonding methods described in

Patent Documents

1 and 2, generally, when an aluminum alloy and a magnesium alloy are directly diffusion bonded, an intermetallic compound phase composed of Al ₃ Mg ₂ , Al ₁₂ Mg ₁₇ or the like is formed at the bonding interface. grow up. This intermetallic compound phase is very fragile and easily formed, so that defects such as cracks and Kirkendall voids are likely to occur. Generally, the tensile strength is about 30 MPa.
In addition, since an oxide film is formed in the bonding process, there is a disadvantage that it must be processed in a reduced pressure or an inert gas atmosphere.
Furthermore, since a pressure holding time of several tens of minutes to several hours is required, the practicality is poor from the viewpoint of strength and productivity.

On the other hand, in the friction stir welding method described in Non-Patent Document 1, although the tensile strength of the joint portion is relatively strong (tensile strength of about 115 MPa: Non-Patent Document 1), in practice, wire bonding or point bonding is used. Therefore, the bondability is insufficient. The friction stir welding method cannot be applied to the joining interface inside the member, and is difficult to apply to a three-dimensional curved surface. For this reason, processing takes time and it is difficult to cope with mass production.

The present invention has been made in view of the above circumstances, and although it is lightweight, it is easy to manufacture a coupling member excellent in bondability between a magnesium member and an aluminum member, and the coupling member, and is excellent in productivity. It aims at providing the manufacturing method of a coupling member.

The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, when the aluminum alloy and the magnesium alloy are directly joined, when the heating and pressurizing such as hot forging is performed, the joining interface is fine under a predetermined condition. It has been found that a mechanical joint interface is formed in addition to diffusion bonding, resulting in an anchor effect and greatly improving the joint strength.
Based on this knowledge, it has been found that the above problem can be solved by providing an intermediate layer made of a predetermined metal between the magnesium member and the aluminum member, and the present invention has been completed.

That is, the present invention is a coupling member comprising (1) a magnesium member made of a magnesium alloy, an aluminum member made of an aluminum alloy, and an intermediate layer formed between the magnesium member and the aluminum member. The layer is made of at least one insert material selected from the group consisting of Ni, Cu, and Ti, and exists in the bonding member that is joined so that the magnesium member, the aluminum member, and the intermediate layer are integrated.

In the present invention, (2) a first diffusion layer made of a magnesium alloy and an insert material is formed at the interface between the magnesium member and the intermediate layer, and an aluminum alloy is formed at the interface between the aluminum member and the intermediate layer. It exists in the coupling member of the said (1) description in which the 2nd diffused layer which consists of insert materials is formed.

The present invention includes (3) an interface between the magnesium member and the first diffusion layer, an interface between the first diffusion layer and the intermediate layer, an interface between the intermediate layer and the second diffusion layer, and an aluminum member and the second diffusion layer. In the connecting member of (2), a mechanical joint by plastic flow is formed at the interface.

The present invention is (4) the method of manufacturing a coupling member according to any one of (1) to (3) above, wherein a magnesium alloy, an insert material made of Ti, and an aluminum alloy are overlapped, It exists in the manufacturing method of the coupling member which joins a magnesium member, an intermediate | middle layer, and an aluminum member by heating in the range of 200 to 450 degreeC, and pressurizing by 100 Mpa-700 Mpa.

The present invention provides (5) the method for producing a coupling member according to any one of (1) to (3) above, wherein a magnesium alloy, an insert material made of Ni or Cu, and an aluminum alloy are laminated. In addition, the present invention resides in a method for manufacturing a bonding member that joins a magnesium member, an intermediate layer, and an aluminum member by heating in a range of 300 ° C. to 400 ° C. and pressurizing at 700 MPa to 750 MPa.

The present invention provides (6) the method for producing a bonded member according to (4) or (5) above, wherein after the magnesium member, the intermediate layer, and the aluminum member are joined, solution treatment and aging treatment are further performed. Exist.

According to the coupling member of the present invention, the brittle aluminum and magnesium described above are provided by providing an intermediate layer made of at least one insert material selected from the group consisting of Ni, Cu and Ti between the magnesium member and the aluminum member. Since no intermetallic compound phase is formed, the bondability between the magnesium member and the aluminum member is excellent over the entire surface via the intermediate layer.
Moreover, the said coupling member is excellent in the lightweight property resulting from a magnesium alloy, and is excellent in mechanical strength or corrosion resistance resulting from an aluminum alloy. For this reason, for example, when used for a wheel of an automobile or the like, it is preferable to reduce the weight by using an aluminum member as the outer side and a magnesium member as the inner side that are easily damaged in a corrosive environment.
Furthermore, since the coupling member is surface-bonded, it can be applied to the bonding interface inside the member and can be applied to a three-dimensional curved surface.

In the above coupling member, a first diffusion layer made of a magnesium alloy and an insert material is formed at an interface between the magnesium member and the intermediate layer, and an aluminum alloy and an insert material are formed at the interface between the aluminum member and the intermediate layer. When the 2nd diffusion layer which consists of is formed, bondability improves more.
In particular, plastic flow occurs at the interface between the magnesium member and the first diffusion layer, the interface between the first diffusion layer and the intermediate layer, the interface between the intermediate layer and the second diffusion layer, and the interface between the aluminum member and the second diffusion layer. In the case where the interface is formed, the area to be diffusion-bonded increases, so that the bondability is further improved.

In the manufacturing method of the coupling member of the present invention, since the coupling member is obtained simply by superimposing a magnesium alloy, a predetermined insert material, and an aluminum alloy and heating and pressing under a predetermined condition, the manufacturing is easy. And excellent in productivity.
Further, when the solution treatment and the aging treatment are performed after joining, it is possible to suppress the aluminum alloy from being annealed, so that the joining property is reliably improved.

FIG. 1 is a cross-sectional view schematically showing a coupling member according to this embodiment. FIG. 2 is a schematic enlarged sectional view of a portion P in FIG. In the coupling member which concerns on Example 1, it is a side view which shows the state which laminated | stacked the magnesium billet, the insert material, and the aluminum billet. FIGS. 4 (a) to 4 (c) show the bonding member according to Example 1 from the state in which the magnesium alloy billet, the insert material, and the aluminum alloy billet are stacked to heat and press until the bonding member is obtained. It is explanatory drawing for demonstrating this process. FIG. 5 is a graph showing the relationship between the tensile strength of the joint surface, the applied pressure during heating, and the heating temperature in Examples 1 to 11. FIG. 6 is a graph showing the relationship between the tensile strength of the joint surface, the applied pressure during heating, and the heating temperature in Examples 12 to 20. FIG. 7 is a graph showing the relationship between the tensile strength of the joining surface and the applied pressure during joining in Examples 21 to 25. FIGS. 8A to 8C are photographs of secondary electron images obtained by a scanning electron microscope (SEM) on the joint surface of the coupling member according to the second embodiment. FIG. 9 is a photograph of a secondary electron image obtained by a scanning electron microscope (SEM) on the joint surface of the coupling member according to Example 22. FIG. 10A to FIG. 10F show the surface analysis results of the coupling member according to Example 2 using an X-ray microanalyzer (EPMA). FIG. 11A to FIG. 11B show the surface analysis results of the coupling member according to Example 22 by X-ray microanalyzer (EPMA). 12 (a) to 12 (d) show the results of line analysis by EPMA of the coupling member according to the second embodiment. FIG. 13A is a line analysis result by EPMA of the coupling member according to Example 22. FIG. FIG. 13B is a line analysis result by EPMA of the coupling member according to Example 22. FIG. 14 shows the relationship between the heating temperature during bonding in the bonding member according to Comparative Example 1, the tensile strength of the obtained bonding member, and the thickness of the intermetallic compound phase composed of aluminum and magnesium formed at the bonding interface. It is a graph to show. 15A and 15B are photographs of secondary electron images obtained by SEM of the coupling member according to Comparative Example 1. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

FIG. 1 is a cross-sectional view schematically showing a coupling member according to this embodiment.
As shown in FIG. 1, a coupling member 100 according to this embodiment includes a magnesium member 1 made of a magnesium alloy, an aluminum member 2 made of an aluminum alloy, and an intermediate layer inserted between the magnesium member 1 and the aluminum member 2. 3. That is, the coupling member 100 has a structure in which the magnesium member 1, the intermediate layer 3, and the aluminum member 2 are laminated in this order and joined together.

The magnesium member 1 is made of an alloy containing magnesium as a main component. For this reason, the coupling member 100 is lightweight, and the magnesium member 1 side has a feature that internal friction is large and vibration and impact are easily absorbed.
Examples of the additive element of the magnesium alloy include aluminum, zinc, calcium, and lithium. The characteristics of the magnesium alloy can be changed by adjusting the blending of these additive metals.
Among these, it is preferable that an additive metal is aluminum and zinc from a versatility viewpoint.

The aluminum member 2 is made of an alloy mainly composed of aluminum. For this reason, the aluminum member 2 side is characterized by excellent mechanical strength.
Examples of the additive element of the aluminum alloy include copper, manganese, silicon, magnesium, zinc, nickel, and the like. The characteristics of the aluminum alloy can be changed by adjusting the blending of these additive metals.
Specifically, Al—Cu alloy (duralumin), Al—Mn alloy, Al—Si alloy, Al—Mg alloy, Al—Mg—Si alloy, Al—Zn—Mg alloy, Al— Zn-Mg-Cu based alloys and the like can be mentioned.

The intermediate layer 3 functions like an adhesive for joining the magnesium member 1 and the aluminum member 2.
The intermediate layer 3 is made of at least one insert material selected from the group consisting of Ni, Cu and Ti.

The thickness of the intermediate layer 3 is preferably 10 μm to 2 mm. In particular, when it is 1 mm, there is an advantage that the applied pressure on the joint surface is easily equalized. When the thickness is less than 10 μm, compared with the case where the thickness is within the above range, for example, when the shape of the coupling member is an arc, a curved surface, a three-dimensional surface, etc., unevenness occurs in the applied pressure, and the magnesium member 1 And the aluminum member 2 may be insufficiently joined. On the other hand, when the thickness exceeds 2 mm, the characteristics of the magnesium member 1 and the aluminum member 2 may not be sufficiently exhibited as compared with the case where the thickness is within the above range, resulting in an increase in weight and cost. There are also drawbacks.

As described above, the bonding member 100 is provided with the intermediate layer 3 made of an insert material between the magnesium member 1 and the aluminum member 2, thereby connecting the magnesium member 1 and the aluminum member 2 via the intermediate layer 3. Is excellent over the entire surface.

FIG. 2 is a schematic enlarged sectional view of a portion P in FIG.
As shown in FIG. 2, in the coupling member 100 according to the present embodiment, a first diffusion layer 11 made of a magnesium alloy and an insert material is formed at the interface between the magnesium member 1 and the intermediate layer 3. A second diffusion layer 12 made of an aluminum alloy and an insert material is formed at the interface between the member 2 and the intermediate layer 3.

In the coupling member 100, a mechanical joint 21 by plastic flow is formed at the interface between the magnesium member 1 and the first diffusion layer 11, and a machine by plastic flow is formed at the interface between the first diffusion layer 11 and the intermediate layer 3. The mechanical joint 22 is formed at the interface between the intermediate layer 3 and the second diffusion layer 12, and the mechanical joint 23 by plastic flow is formed at the interface between the aluminum member 2 and the second diffusion layer 12. A mechanical joint 24 is formed by plastic flow.
Here, the mechanical joint means a fine concavo-convex part formed by plastic flow on the boundary surface, thereby exhibiting an anchor effect.

Therefore, in the coupling member 100, not only the first diffusion layer 11 and the second diffusion layer 12 are provided, but also the mechanical joints 21 to 24 that are fine plastic flow interfaces exhibit an anchor effect. Therefore, high strength surface bonding is achieved. In addition, in the formation of the plastic flow interface, the bonding strength is further improved by increasing the area to be diffusion bonded.

The coupling member 100 according to the present embodiment is lightweight due to the magnesium alloy, and has excellent corrosion resistance and mechanical strength due to the aluminum alloy. For this reason, it is suitably used for applications such as a vehicle wheel, a housing, a structural member (clad material), and a casing in an electronic device. For example, when it is used for a vehicle wheel, it is preferable that the outer side which is easily damaged in a corrosive environment is an aluminum member and the inner side is a magnesium member.
In addition to these, since various three-dimensional molded products can be provided by pressing the connecting member, products with reduced weight can be provided over a wide range of fields.

Next, a method for manufacturing the coupling member 100 will be described.
The bonding member 100 is formed by laminating a magnesium alloy, an insert material, and an aluminum alloy, and heating and pressurizing the magnesium member 1, the intermediate layer 3 made of the insert material, and an aluminum member made of the aluminum alloy. 2 is obtained by joining them so as to be integrated with each other.

First, a magnesium alloy, a sheet of at least one insert material selected from the group consisting of Ni, Cu and Ti, and an aluminum alloy are laminated.

At this time, the surface roughness (Rz) of the surface laminated with the insert material of the magnesium alloy is 10 μm or less, and the surface roughness (Rz) of the surface laminated with the insert material of the aluminum alloy is 10 μm or less. In addition, it is preferable that the surface is clean and has a natural oxide film level by polishing. In this case, the bonding strength is further improved.
Here, the surface roughness (Rz) means a value measured according to JIS B0601 (2001).

Then, the whole member is heated and pressed to form the first diffusion layer and the second diffusion layer on the bonding surface, whereby the coupling member 100 is obtained. At this time, it is preferable to form the mechanical joint by the fine plastic flow described above. Then, when the insert material is Ni or Cu, the tensile strength of the joint surface reaches at least 115 MPa to 120 MPa, and when the insert material is Ti, the tensile strength of the joint surface reaches at least 154 MPa.

Here, when the insert material is Ti, the heating temperature is preferably in the range of 200 ° C. to 450 ° C., more preferably in the range of 200 ° C. to 400 ° C., and in the range of 300 ° C. to 350 ° C. More preferably it is.
If the temperature is lower than 200 ° C., the plastic flow may be reduced as compared with the case where the temperature is within the above range, resulting in insufficient bonding. Further, when the temperature exceeds 450 ° C., the diffusion reaction layer may grow more than necessary and the bonding may be insufficient as compared with the case where the temperature is within the above range.

When the insert material is Ti, the pressure applied is preferably in the range of 100 MPa to 700 MPa.
When the pressure is less than 100 MPa, bonding may be insufficient as compared with the case where the pressure is within the above range, and when the pressure exceeds 700 MPa, the pressure is within the above range. Further, the plastic flow becomes too large, the insert material is broken, a brittle intermetallic compound is generated by the direct reaction between the magnesium alloy and the aluminum alloy, and the strength may be lowered due to the generation of defects such as cracks and Kirkendall voids.

When the insert material is Ni or Cu, the heating temperature is preferably in the range of 300 ° C to 400 ° C.
If the temperature is lower than 300 ° C., the plastic flow may be reduced as compared with the case where the temperature is within the above range, resulting in insufficient bonding. Further, when the temperature exceeds 400 ° C., the diffusion reaction layer may grow more than necessary and the bonding may be insufficient as compared with the case where the temperature is within the above range.

When the insert material is Ni or Cu, the pressure applied is preferably in the range of 700 MPa to 750 MPa.
If the pressure is less than 700 MPa, bonding may be insufficient as compared with the case where the pressure is within the above range, and if the pressure exceeds 750 MPa, the pressure is within the above range. Further, the plastic flow becomes too large, the insert material is broken, a brittle intermetallic compound is generated by the direct reaction between the magnesium alloy and the aluminum alloy, and the strength may be lowered due to the generation of defects such as cracks and Kirkendall voids.

Although it does not specifically limit as a method to heat-press, For example, hot forging etc. are mentioned.
In addition, when heating and pressurization is performed under reduced pressure in the atmosphere or in an inert gas atmosphere, formation of an oxide film that causes a decrease in bondability can be suppressed. For this reason, higher strength bonding can be expected. In addition, the state of each joint surface of the magnesium alloy, insert material, and aluminum alloy before joining needs to be adjusted by grinding | polishing etc. (state about a natural oxide film).

In addition, after joining a magnesium member, an intermediate | middle layer, and an aluminum member, it is preferable to perform a solution treatment and an aging treatment further.
In this case, since it can suppress that an aluminum alloy will be in the annealing state, bondability improves reliably. This is particularly effective when hot forging is performed.

According to the manufacturing method of a coupling member, since a coupling member is obtained simply by laminating a magnesium member, an intermediate layer, and an aluminum member, and heating and pressing under predetermined conditions, the production is easy. Excellent productivity. That is, in the atmosphere, for example, three-dimensional surface bonding is possible in a short time of about 20 seconds, so that it is possible to improve mass productivity and reduce costs.

The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

For example, the coupling member according to the present embodiment has a two-layer structure of a magnesium member and an aluminum member, but may have three or more layers. That is, the aluminum member may be laminated on both surfaces of the magnesium member, and the magnesium member may be laminated on both surfaces of the aluminum member.

Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples.

(Examples 1 to 25 and Reference Examples 1 to 10)
First, a magnesium alloy billet (diameter 204 mm, height 184 mm) cast into a columnar shape of AZ80 (magnesium alloy), and an intermediate layer (100 mm × 100 mm × 1 mm (100 mm × 100 mm × 1 mm) made of insert materials (Ni, Cu, Ti) shown in Table 1 Thickness)) and an aluminum alloy billet (diameter 204 mm, height 184 mm) cast into a cylindrical shape of A6151 (aluminum alloy). When Ti was used as the insert material, A2000 series alloy A2017 (duralumin) was used as the aluminum alloy instead of A6151.

Next, the joint surfaces of the magnesium alloy billet and the aluminum alloy billet were ground, polished with a SiC # 1000 abrasive paper, and further the surface was degreased with acetone. The surface roughness (Rz) was Rz = 3.4 μm at the center of the aluminum alloy billet side surface, and the surface roughness Rz = 2.6 μm at the magnesium alloy billet side.

Then, as shown in FIG. 3, a magnesium alloy billet 31, an intermediate layer 33, and an aluminum alloy billet 32 are laminated, and in order to fix them, connecting plate members 34 are bolted to the side surfaces of the magnesium alloy billet 31 and the aluminum alloy billet 32. 35 and screwed. As shown in Table 1, the weight of the laminated magnesium alloy billet 31, intermediate layer 33 and aluminum alloy billet 32 (hereinafter simply referred to as “laminated body”) was about 27 kg. In Table 1, “-” means not measured.

Next, as shown in FIG. 4A, a laminated body 36 is installed between a lower die 37 for flat pressing and an upper die 38 of a press machine having a pressurizing force of 9000 tons. The laminate 36 was placed on the mold 37.
Thereafter, the laminate was heated under the temperature conditions shown in Table 2 and pressurized for 20 seconds under the pressure conditions shown in Table 1 as shown in FIG. In Table 2, “-” means that no measurement was performed.
And after natural cooling, it formed into the solution by heat processing and age-hardened, and the coupling member 40 shown to (c) of FIG. 4 was obtained.

(Table 1)

(Table 2)

(Evaluation 1)
Samples were taken in the direction perpendicular to the bonding interface for the bonding members obtained in Examples 1 to 25 and Reference Examples 1 to 10, and based on JIS-Z2241 (metal material tensile test method), the tensile strength of the bonding members Was measured. Each sample was evaluated twice by collecting samples from different locations.
The obtained results are shown in Table 3.

(Table 3)

From the results shown in Table 3, it was found that the joining member of Example 2 using Ni as the insert material and having a heating temperature of 300 ° C. and a pressing force of 750 MPa exhibits a tensile strength of about 120 MPa at the maximum.
The joining members of Examples 12 to 17 using Cu as the insert material had a maximum tensile strength of about 100 MPa.
It was found that when the insert material is Ni or Cu, it is not joined at a low temperature (tensile strength of 0 MPa), but it suddenly joins when a certain temperature is exceeded. This is thought to be related to the formation of a plastic flow interface. Further, it was found that the tensile strength tends to decrease conversely when the temperature is increased beyond the point at which the joining becomes abrupt. The reason why the tensile strength decreases as the processing temperature rises is considered to be because a fragile diffusion layer grows thicker than necessary compared to the base material (in order to obtain a high-strength diffusion bonding phase, generally the reaction layer The thinner the better.)

The joining member of Example 22 using Ti as the insert material, A2017 as the aluminum alloy, heating temperature 300 ° C., and pressurizing force 200 MPa showed the highest tensile strength σ _B = 151.0 MPa. The tensile strength σ _B = 120 MPa or more was recorded even when the applied pressure was 100 MPa, 300 MPa, 500 MPa, and 700 MPa. From these results, it was found that Ti was the most excellent insert material compared to Ni and Cu (not only the tensile strength but also the tolerance of the processing range).

FIG. 5 shows the relationship between the tensile strength of the joint surface in Examples 1 to 11 and the applied pressure and heating temperature at the time of joining, and the tensile strength of the joined surface in Examples 12 to 20, the applied pressure and heating at the time of joining. FIG. 6 shows the relationship with temperature, and FIG. 7 shows the relationship between the tensile strength of the joint surface in Examples 21 to 25 and the applied pressure during joining. In addition, in FIG. 7, the value with the higher result of the tensile strength shown in Table 3 is shown.

(Evaluation 2)
The joint part of the coupling member obtained in Example 2 and Example 22 was photographed with a scanning electron microscope (SEM). In SEM, an electron beam is squeezed into an electron beam to irradiate the object and detect secondary electrons emitted from the object or reflected electrons reflected by the object. Can be observed. The secondary electron images obtained in Example 2 are shown in FIGS. 8A to 8C, and the secondary electron beam obtained in Example 22 is shown in FIG.

(A) of FIG. 8 is a photograph of the joining part of a magnesium member, an intermediate | middle layer (Ni), and an aluminum member whose measurement scale is 200 micrometers. FIG. 8B is a photograph of a joint portion between the magnesium member and the intermediate layer (Ni) having a measurement scale of 20 μm. (C) of FIG. 8 is a photograph of the joint portion between the intermediate layer and the aluminum member having a measurement scale of 20 μm.
In the cross-sectional observation of FIG. 8, no defects such as cracks and Kirkendall voids that were easily formed during direct diffusion bonding of aluminum and magnesium were observed.

In FIG. 9, the description of arrows Line1 and Line2 indicates the joint surface and the measurement direction of the line analysis described later. The upper part of the photograph is a magnesium alloy (AZ80), the central part is an insert material Ti, and the lower part is an aluminum alloy (A2017, duralumin). The measurement scale is 100 μm.

(Evaluation 3)
The joint interface of the coupling members obtained in Example 2 and Example 22 was subjected to surface analysis using an electron beam microanalyzer (EPMA). In EPMA, constituent elements can be analyzed from the wavelength of characteristic X-rays generated by irradiating an object with an electron beam. The surface analysis images obtained in Example 2 are shown in FIGS. 10 (a) to 10 (f), and the surface analysis images obtained in Example 22 are shown in FIGS. 11 (a) to 11 (b). ).

10 (a) to 10 (c), the measurement scale is 5 μm, the upper side is a magnesium member, and the lower side is an intermediate layer (Ni). FIG. 10 (d) to FIG. In (f), the measurement scale is 5 μm, the upper side is the intermediate layer (Ni), and the lower side is the aluminum member. In addition, (a) of FIG. 10 is a secondary electron image. FIG. 10B is a reflected electron image. (C) of FIG. 10 is a surface analysis result of magnesium. FIG. 10D shows the Ni surface analysis results. (E) of FIG. 10 is a surface analysis result of aluminum. (F) of FIG. 10 is an oxygen surface analysis result.
From FIG. 10 (f), the presence of fine oxides was clearly confirmed (existing from the interface to the magnesium alloy side to about 10 μm). Since this was a processing process in the atmosphere, it is considered that a certain amount of oxide was formed. This also coincides with the signal intensity changing portions of (a), (b), (c) and (e) of FIG.

In FIG. 11 (a) to FIG. 11 (b), the measurement scale is 5 μm. 11A is a surface analysis result of the joint surface between the magnesium alloy AZ80 and the insert material Ti along the Line 1 in FIG. 9, where SL is a secondary electron image, and CP is a reflected electron. It is a statue. Mg, Ti, Al, and O represent each element analyzed.
In the case of the analysis photograph Mg in FIG. 11 (a), the upper part is a magnesium alloy AZ80 and the lower part is an insert material Ti. A thin diffusion layer and a fine plastic flow interface are formed at the interface (anchor effect). Looking at the phase diagram of the binary system, it is considered that these diffusion reactions are small because Ti has very little mutual dissolution with Mg. The diffusion reaction in this case is considered to be mainly the Al component and Ti in the Mg alloy. That is, it is considered that the use of Ti for the insert material can suppress the growth of the fragile Mg reaction layer as much as possible, thereby obtaining a high-strength diffusion layer.
In the case of the analysis photograph Ti in FIG. 11 (b), the upper surface portion is Ti and the lower surface portion is an aluminum alloy. A diffusion reaction is observed at the bonding interface. In the photograph in which Al is described, the upper part is Ti and the lower part is an aluminum alloy. As in the case of the AZ80 alloy side, formation of a good diffusion layer that is thin and free from defects was confirmed.

11 (b), the upper part of each photograph is the insert material Ti, and the lower part is aluminum alloy A2017 (duralumin). SL described in the photograph is a secondary electron image, and CP is a reflected electron image. In the figure described in Ti, formation of a thin diffusion layer and a fine plastic flow interface (anchor effect) is recognized at the interface. Similarly, formation of a thin diffusion layer and a plastic flow interface is recognized at the interface in the diagram described in Al. In the photograph described in O, the presence of a particularly remarkable oxide is not recognized.

(Evaluation 4)
In the same manner as in Evaluation 3, the joint portion of the coupling member obtained in Example 2 and Example 22 was subjected to line analysis by EPMA. The line analysis graphs obtained in Example 2 are shown in FIGS. 12 (a) to 12 (d), and the line analysis graphs obtained in Example 22 are shown in FIGS. 13 (a) and 13 (b). ).

(A) of FIG. 12 is a line analysis corresponding to (c) of FIG. 10, and shows the analysis result of magnesium. The scanning direction is perpendicular to the interface from the magnesium alloy side to the Ni insert material direction. The vertical axis represents the intensity of the generated characteristic X-ray, and the horizontal axis represents the scanning distance (mm). The horizontal axis of the graph is one scale of 0.001 mm (1 μm), and shows a boundary portion between a portion where magnesium is present and a portion where magnesium is not present. That is, it is a portion where a diffusion layer with nickel (Ni) can be read. FIG. 12B shows the result of nickel line analysis. It can be seen that a magnesium member and a diffusion layer of about 1 μm are formed. It turns out that it is a very thin diffusion layer, and it can be understood that it is a favorable diffusion layer. (C) of FIG. 12 is a line analysis result of aluminum. FIG. 12 (d) shows the results of oxygen line analysis. It can be confirmed that the oxide layer Q is detected. Note that this portion corresponds to the oxide layer shown in FIG. The thickness of the oxide layer was about 10 μm.

FIG. 13A is performed along Line 1 in FIG. 9, and FIG. 13B is performed along Line 2 in FIG. In addition, the type of element to be analyzed is described for each graph. In FIG. 13, CP indicates the reflected electron intensity. Mg, Ti, Al, and O represent the element symbols analyzed. The horizontal axis is the scanning distance, and the unit is (mm).

FIG. 13A shows that the diffusion layer is about 2 μm. Magnesium has low mutual solubility with Ti. By using Ti as an intermediate material, reaction with Mg is suppressed as much as possible, while thin and good diffusion layers can be obtained by mainly reacting with Al in the magnesium alloy. As a result, a high-strength joint interface can be formed together with a fine plastic flow interface (a synergistic effect of mechanical joining (anchor effect) and metallurgical joining (diffusion reaction)). From the results of the oxygen line analysis, it can be understood that the formation of a fragile oxide layer is very small in Ti compared to Ni (FIG. 12) (contributes to high strength).

FIG. 13B shows that a thin and good diffusion layer is formed between Ti and Al at the bonding interface between the insert material (Ti) and A2017. The thickness of the diffusion reaction layer seems to be around 1 μm (very thin with a resolution determined by the region where characteristic X-rays are generated). It can also be seen that there is almost no generation of oxide at the bonding interface.

(Comparative Example 1)
A coupling member was obtained in the same manner as in Example 1 except that the insert material serving as the intermediate layer was not used. That is, a magnesium alloy (AZ80) and an aluminum alloy (A6151) are directly brought into contact with each other to form a laminate, and the laminate temperature is set to 360 ° C., 385 ° C., 400 ° C., and 420 ° C. Went.

(Evaluation 5)
The tensile strength of the coupling member obtained in Comparative Example 1 was measured in the same manner as in Evaluation 1. The obtained result is shown in FIG.
As shown in FIG. 14, the joint member of Comparative Example 1 showed a tendency for the tensile strength to increase rapidly at a processing temperature of 420 ° C. (tensile strength σ _B = 55 MPa).
At lower temperatures, the tensile strength was in the range of σ _B = 10 MPa to 30 MPa.
The reason why the tensile strength suddenly increases at 420 ° C. is that the formation of the plastic flow interface becomes remarkable above this temperature.
However, in this Al—Mg direct bonding method using no insert material, an intermetallic compound phase (Al ₁₂ Mg ₁₇ , Al ₃ Mg ₂ ) that is extremely brittle and has many defects is easily formed (FIG. 14).
In direct bonding, a certain degree of tensile strength (about 55 MPa) can be obtained by forming a plastic flow interface by hot forging, but it is inevitable to form critical defects such as cracks and voids that are the starting point of fracture. Therefore, it can be understood that the use of appropriate insert materials is essential.

(Evaluation 6)
For the coupling member obtained in Comparative Example 1, the joint portion of the coupling member was photographed with a scanning electron microscope (SEM) in the same manner as in Evaluation 2. The obtained secondary electron images are shown in FIGS. 15 (a) and 15 (b).
As shown in FIGS. 15A and 15B, layers of Al ₁₂ Mg ₁₇ and Al ₃ Mg ₂ as intermetallic compounds were confirmed on the magnesium member side. In FIG. 15A, cracks were observed, and in FIG. 15B, Kirkendall voids (holes resulting from the difference in diffusion rate) were generated. This result demonstrates the superiority of using an intermediate layer that forms a good diffusion layer.

The bonding member of the present invention is lightweight and has excellent durability due to the magnesium alloy, and has excellent mechanical strength due to the aluminum alloy. For this reason, it is suitably used for applications such as a vehicle wheel, a housing, a structural member (clad material), and a casing in an electronic device.

DESCRIPTION OF SYMBOLS 1 ... Magnesium member 2 ...

Aluminum member

3,33 ... Intermediate | middle layer 11 ... 1st diffused layer 12 ... 2nd diffused

layer

21, 22, 23, 24 ... Mechanical junction 31 ... Magnesium alloy billet 32 ... Aluminum alloy billet 34 ... Connecting plate material 35 ... Bolt 36 ... Laminate 37 ... Lower mold 38 ...

Upper mold

40, 100 ...・ Coupling member P ... part Q ... oxide layer

Claims

A coupling member comprising a magnesium member made of a magnesium alloy, an aluminum member made of an aluminum alloy, and an intermediate layer formed between the magnesium member and the aluminum member,
The intermediate layer is made of at least one insert material selected from the group consisting of Ni, Cu and Ti,
The coupling member joined so that the said magnesium member, the said aluminum member, and an intermediate | middle layer may be united.
A first diffusion layer made of the magnesium alloy and the insert material is formed at the interface between the magnesium member and the intermediate layer,
The coupling member according to claim 1, wherein a second diffusion layer made of the aluminum alloy and the insert material is formed at an interface between the aluminum member and the intermediate layer.
The interface between the magnesium member and the first diffusion layer, the interface between the first diffusion layer and the intermediate layer, the interface between the intermediate layer and the second diffusion layer, and the aluminum member and the second diffusion layer The coupling member according to claim 2, wherein a mechanical joint portion by plastic flow is formed at an interface with.
A method for manufacturing a coupling member according to any one of claims 1 to 3,
The magnesium alloy, the insert material made of Ti, and the aluminum alloy are overlaid, heated to a range of 200 ° C. to 450 ° C., and pressurized at 100 MPa to 700 MPa, thereby the magnesium member, the intermediate layer, A method for manufacturing a coupling member for joining the aluminum member.
A method for manufacturing a coupling member according to any one of claims 1 to 3,
The magnesium member, the insert material made of Ni or Cu, and the aluminum alloy are overlaid, heated to a range of 300 ° C. to 400 ° C., and pressurized at 700 MPa to 750 MPa, whereby the magnesium member and the intermediate layer And the manufacturing method of the coupling member which joins the said aluminum member.
6. The method for manufacturing a coupling member according to claim 4, wherein after the magnesium member, the intermediate layer, and the aluminum member are joined, a solution treatment and an aging treatment are further performed.