JP6652674B1 - Method of manufacturing composite member and composite member - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a composite member capable of efficiently producing a composite member having high bonding strength. A method of manufacturing a composite member including a Cu-based metal member and an Al alloy member, comprising using a press mold having a cavity and a surplus portion communicating with the cavity, wherein the press mold includes: An insert installation step of installing the Cu-based metal member as an insert; a semi-solid metal supply step of supplying a semi-solid state Al alloy into the press die; and the semi-solid state Al by the press die. A pressing step of applying pressure to the alloy to form the cavity shape, filling a part of the Al alloy in the excess portion, and forcing the Al alloy filled in the excess portion into the cavity. And a press-fitting step of press-fitting the composite member. [Selection diagram] Fig. 1

Description

  The present invention relates to a method for manufacturing a composite member including a Cu-based metal member and an Al alloy member. The present invention also relates to a composite member including a Cu-based metal member and an Al alloy member.

  Composite members made of a plurality of dissimilar metals are used in various applications because they have various functions depending on the combination of metals. Among them, a composite member composed of a Cu-based metal member and an Al alloy member, in addition to Cu having high conductivity and heat conductivity, Al has relatively good conductivity and heat conductivity while being lightweight. For this reason, it is widely used as a conductive member such as a battery electrode and a heat conductive member such as a heat sink and a heat pipe.

  As a method of joining metals, mechanical methods such as caulking and welding have been used for a long time. However, when a Cu-based metal member and an Al alloy member are joined by these methods, there is a problem that strength, electrical conductivity, thermal conductivity, and the like at the joint are inferior.

  In recent years, dissimilar metals have also been joined using friction joining (friction welding). Friction welding is a joining method that uses frictional heat generated by rotating the material to be joined at high speed, so there is no need to separately prepare a heat source, and it is not necessary to use a welding rod or flux. There is an advantage.

  For example, Patent Literature 1 discloses that a copper rod is joined to an aluminum member by friction joining. At that time, in the technique proposed in Patent Document 1, the tip of the copper rod is formed into a tapered shape and the surface is provided with irregularities.

JP-A-07-47480

  According to the above friction joining, dissimilar metals can be easily joined. Further, it is considered that the use of the technique proposed in Patent Document 1 can improve the joining strength when joining dissimilar metals by friction joining.

  However, friction welding still has the following problems.

  In the friction welding, since the materials to be joined are joined by rotating at high speed, the shape of the material to be rotated on the side to be rotated is a shape suitable for rotation, specifically, as shown in Patent Document 1. It is limited to cylindrical shape.

  In addition, both the material to be rotated and the other material to be rotated need to have strength enough to withstand the force applied during high-speed rotation, and are limited to shapes that can be fixed with a chuck or the like.

  Furthermore, in order to make the shape of the composite member the shape of the final product, it is necessary to form the material to be joined before performing the friction joining or to form after joining. Therefore, productivity is low because molding and joining must be performed separately.

  For the above reasons, there is a demand for a method of manufacturing a composite member having a high degree of freedom in shape and excellent in productivity.

  On the other hand, insert molding is also known as a method for producing a composite member made of a dissimilar metal. In the insert molding, a method of manufacturing a composite member in which an insert is integrated by pouring a molten metal (metal in a molten state) into the mold while a member called an insert is set inside the mold and solidifying the molten metal. .

  According to the insert molding, high productivity can be obtained because joining with the insert can be performed simultaneously with metal molding using a mold. However, the composite member obtained by insert molding has insufficient strength at the joint, and its use range is limited.

  The present invention has been made in view of the above circumstances, and has as its object to provide a method for manufacturing a composite member capable of efficiently producing a composite member having high bonding strength. Another object of the present invention is to provide a composite member having high bonding strength.

  The inventors have conducted repeated studies to solve the above problems, and as a result, when manufacturing a composite member including a Cu-based metal member and an Al alloy member as an insert, using an Al alloy in a semi-solid state, In addition, it has been found that a composite member having extremely excellent bonding strength can be manufactured by forcibly pressing an Al alloy filled in a surplus portion (also referred to as a thickened portion) provided in a mold into a cavity.

  The present invention has been made based on the above findings, and the gist configuration thereof is as follows.

1. A method for manufacturing a composite member including a Cu-based metal member and an Al alloy member,
Using a press mold having a cavity and a surplus portion communicating with the cavity,
An insert installation step of installing the Cu-based metal member as an insert in the press mold,
In the press die, a semi-solid metal supply step of supplying a semi-solid Al alloy,
A press step of applying pressure to the semi-solidified Al alloy by the press mold to form the cavity shape, and filling a part of the Al alloy in the excess portion.
Press-fitting the Al alloy filled in the excess portion into the cavity.

2. The method for producing a composite member according to claim 1, further comprising an electromagnetic stirring step of bringing the molten metal obtained by melting the Al alloy into a semi-solid state while applying electromagnetic stirring to the molten metal prior to the semi-solid metal supplying step.

3. 3. The method of manufacturing a composite member according to the above item 1 or 2, wherein the volume of the excess portion is 3 to 8% of the volume of the cavity.

4. A composite member comprising a Cu-based metal member and an Al alloy member,
The Cu-based metal member and the Al alloy member are joined via a Cu-Al-based alloy layer present at an interface between the Cu-based metal member and the Al alloy member,
A composite member, wherein the Al alloy member has a forged structure.

  According to the present invention, a composite member having high bonding strength can be obtained. In addition, according to the manufacturing method of the present invention, since the joining with the insert and the shaping into a product shape can be performed simultaneously, the productivity is excellent. Further, the manufacturing method of the present invention is not limited by the shape as in the case of friction welding. In addition, the composite member of the present invention is not only excellent in bonding strength but also excellent in proof stress in the base material portion of the Al alloy member.

It is a mimetic diagram showing a manufacturing process of a compound member in one embodiment of the present invention. It is drawing which shows the shape of the composite member created in the Example. It is a microscope photograph of the joined part in the composite member obtained in the example. 6 is a micrograph of a joint in the composite member obtained in Comparative Example 1. 9 is a micrograph of a joint in a composite member obtained in Comparative Example 2.

  Next, a method for carrying out the present invention will be specifically described.

  The method for manufacturing a composite member according to one embodiment of the present invention is a method for manufacturing a composite member including a Cu-based metal member and an Al alloy member.

[Cu-based metal member]
The Cu-based metal member is not particularly limited, and a member made of an arbitrary Cu-based metal can be used. As the Cu-based metal, any of copper (pure copper) and copper alloy can be used. The copper alloy is not particularly limited, and any copper-containing alloy can be used, but a copper-based alloy is preferably used.

  When copper is used as the copper-based metal, it is preferable to use tough pitch copper from the viewpoint of electrical conductivity and thermal conductivity.

  The shape of the Cu-based metal member is not particularly limited, and may be any shape. Examples of the shape of the Cu-based metal member include a plate shape, a rod shape (a column shape, a prism shape, and the like), a pipe shape, and a shape obtained by combining them, and the like, but a more complicated shape can also be used.

[Al alloy members]
The Al alloy member is not particularly limited, and a member made of any Al alloy can be used. The Al alloy is not particularly limited, and any alloy containing aluminum can be used, but an aluminum-based alloy is preferably used.

  As typical aluminum alloys, wrought alloys and casting alloys are known, and in the present invention, any of them can be used as the aluminum-based alloy. As the aluminum-based alloy, for example, an alloy containing one or more selected from the group consisting of Cu, Si, Mg, Ni, Mn, and Zn as an alloying element, and the balance being Al and unavoidable impurities It is preferable to use Examples of the aluminum-based alloy include an Al-Si alloy, an Al-Si-Mg alloy, an Al-Mg alloy, an Al-Si-Cu alloy, an Al-Si-Cu-Mg alloy, and an Al-Mn alloy. One or two or more selected from the group consisting of a system alloy, an Al-Cu system alloy, an Al-Zn-Mg system alloy, and an Al-Zn-Mg-Cu system alloy can be used.

  The shape of the Al alloy member is not particularly limited, and may be any shape. In the present invention, a semi-solid Al alloy is formed by a press die as described later. Therefore, by designing the cavity shape of the press die so as to have a desired product shape, it is possible to manufacture a composite member having an arbitrary shape.

[Manufacturing process]
In one embodiment of the present invention, a composite member is manufactured by using a press die having a cavity and a surplus portion communicating with the cavity and performing the following steps (1) to (4). . Hereinafter, each step will be described. The following steps (1) to (4) may be performed sequentially, but at least one step may be performed simultaneously with at least one other step or at an overlapping timing.
(1) Insert installation step of installing a Cu-based metal member as an insert in a press die (2) Semi-solid metal supply step of supplying a semi-solid state Al alloy into a press die (3) Press die Pressing the semi-solidified Al alloy into a cavity shape by pressurizing the Al alloy, and pressing a part of the Al alloy into a surplus portion (4) placing the Al alloy filled in the surplus portion into the cavity Press-in process for forcible press-in

  FIG. 1 is a schematic view illustrating a manufacturing process of a composite member according to an embodiment of the present invention. In the present embodiment, as shown in FIG. 1A, a lower die 10 and an upper die 20 are used as press dies. Inside the lower mold 10, a cavity 11 having a shape corresponding to the shape of the composite member to be finally manufactured is formed. The lower mold 11 is provided with a surplus portion 12 communicating with the cavity 11. The surplus portion is an extra space not included in the shape of the final composite member.

A pressurizing device 30 is disposed outside the lower mold 11, and the pressurizing plunger 31 is driven to pressurize the excess portion 12.

(1) Insert Installation Step In the insert installation step, a Cu-based metal member (not shown) as an insert is installed in the press die. The installation position of the insert is not particularly limited, and may be a position corresponding to a product to be manufactured. Also, the number of inserts is not particularly limited, and may be any number of one or two or more.

  It is preferable that the insert is fixed to at least one of the lower mold 11 and the upper mold 12. For example, the insert can be fixed by providing an insert holding portion (not shown) for holding the insert in either the lower mold 11 or the upper mold 12. As the insert holding portion, for example, a concave portion for inserting and holding at least a part of the insert can be used.

(2) Semi-solid metal supply step Next, a semi-solid Al alloy is supplied into the press die (semi-solid metal supply step). Such a method of molding using a metal in a semi-solid state (semi-solid metal) is also called a semi-solid method or a semi-solid molding method. A semi-solid metal is a metal in which a liquid phase and a solid phase coexist between a liquidus line and a solidus line of the metal. Since the semi-solid metal has a lower temperature than the molten metal, the use of the semi-solid metal can extend the life of the mold as compared with the case of using a molten metal. In addition, such a metal in a semi-solid state is also referred to as a semi-solid slurry.

  The method for bringing the Al alloy into a semi-solid state is not particularly limited, and any method can be used. Normally, a semi-solid metal can be obtained by melting an Al alloy once and then cooling it while stirring as necessary to grow primary crystals into grains. The stirring can be performed by any method such as mechanical stirring, ultrasonic stirring, and electromagnetic stirring, but it is preferable to use electromagnetic stirring. Hereinafter, the case where electromagnetic stirring is used will be further described.

[Electromagnetic stirring step]
The method for producing a composite member according to one embodiment of the present invention further includes an electromagnetic stirring step of bringing the molten metal obtained by melting the Al alloy into a semi-solid state while applying electromagnetic stirring to the molten metal prior to the semi-solid metal supply step. .

  Generally, when a semi-solid metal is produced from a molten metal, the temperature is lowered while the molten metal is placed in a container (cup, cylinder, or the like), and a solid-liquid coexisting state is obtained. At this time, since the temperature of the molten metal decreases mainly due to heat removal to the container, a nucleus is formed on a contact surface with the container, and a dendrite-like structure grows from the nucleus as a base point.

  On the other hand, when electromagnetic stirring is performed, the nuclei formed on the contact surface with the container in contact with the molten metal are diffused into the molten metal by stirring and vibration, and as a result, spherical and fine crystal nuclei are dispersed. A semi-solid metal can be obtained. Therefore, when the semi-solid metal is produced by using electromagnetic stirring, the structure of the Al alloy portion in the finally obtained composite member becomes fine and uniform, and the mechanical properties such as strength and toughness are further improved. Specifically, in the method of the present invention, when a semi-solid metal produced by using electromagnetic stirring is used, the average particle size of the Al alloy member portion of the finally obtained composite member can be 50 μm or less. . Here, the average particle diameter indicates an average circle equivalent diameter.

  After preparing a semi-solid Al alloy, the semi-solid Al alloy is supplied into a press die. The supply position is not particularly limited, and may be any position. For example, as in the embodiment shown in FIG. 1 (b), it can be supplied to substantially the center in the cavity 11 of the lower die 10.

(3) Pressing Step Thereafter, pressure is applied to the semi-solidified Al alloy by a press die to form a cavity shape. In the present invention, in the pressing step, it is important to fill a part of the semi-solidified Al alloy into the excess wall portion.

  In the embodiment shown in FIG. 1, pressure is applied to the semi-solidified Al alloy by moving the upper die 20 downward by a pressing means (not shown) (FIGS. 1 (c) and 1 (d)). At the time of the pressing step, the press-fit plunger 31 is retracted downward, and the excess portion 12 exists as a space continuous with the cavity 11. Therefore, the Al alloy pressed by the upper mold 20 is filled in the cavity 11 and the excess portion 12 while being pressed.

  The pressing means is not particularly limited, and any pressing means can be used. For example, a general press can be used, but it is preferable to use a servo press in that the pressing conditions can be precisely controlled.

  The press load is not particularly limited, but is preferably 800 kN or more, and more preferably 1000 kN or more, from the viewpoint of enhancing the effect of the press-fitting step described later and further improving the bonding strength. On the other hand, the upper limit of the press load is not particularly limited, but is generally preferably 2000 kN or less, more preferably 1800 kN or less.

(4) Press-in Step In the press-in step, the Al alloy filled in the excess portion is forcibly pressed into the cavity. Specifically, as shown in FIG. 1 (e), the press-fitting plunger 31 is driven by the pressurizing device 30 to remove all the Al alloy existing inside the excess thickness portion 12 from the cavity 11. Push inside. The press-fitting may be performed until the Al alloy inside the cavity 11 is completely solidified.

  By forcibly pressing the excess Al alloy into the cavity, the metal in the cavity flows and is compressed. As described above, the temperature of the Al alloy is increased by further compressing under pressure by the press die, and as a result, diffusion of atoms at the interface between the Cu-based metal member and the Al alloy is promoted. Then, a thick alloy layer (Cu-Al-based alloy layer) is formed at the interface. By forming such a thick alloy layer, the bonding strength between the Cu-based metal member and the Al alloy can be effectively increased. As described above, in the present invention, in order to increase the bonding strength, it is extremely important to perform press-fitting from a surplus portion. Further, in the composite member thus obtained, since the Cu-based metal member and the Al alloy are metallurgically joined via the Cu-Al-based alloy layer, the Cu-based metal member and the Al alloy are joined together. It is also excellent in electrical and thermal conductivity between layers.

  In a method using a normal molten metal that is not in a semi-solid state, such an interface alloy layer is not formed, or even if formed, it is negligible, and the joining strength cannot be substantially improved. Even when a semi-solid metal is used, the effect of heat due to compression cannot be obtained unless press-fitting from the excess portion, and the interface alloy layer grows insufficiently. That is, it can be said that the above-described excellent effects of the present invention can be obtained only when the three items of the insert formation, the use of the semi-solid metal, and the press-fitting from the excess portion are combined.

  Further, when the press-fitting is not performed, the structure of the finally obtained member is constituted by substantially spherical particles, as in the case of die casting using a normal semi-solid metal. On the other hand, in the present invention, since a large compressive force acts on the semi-solid metal in the cavity by performing press-fitting from the excess portion while pressure is applied by the mold, the structure of the member finally obtained is Is composed of compressed flat particles. The structure is similar to a work structure formed by plastic deformation, and is called a forged structure or a work flow structure. That is, in the composite member according to one embodiment of the present invention, at least a part, preferably the whole, of the Al alloy member has a forged structure.

  Furthermore, at the time of the above-described press-fitting, a shear force acts due to collision of primary crystals of the Al alloy. As a result, in addition to generating frictional heat, dislocations are introduced into the primary crystal. Thereby, a compressive stress is generated inside the Al alloy, and the proof stress is improved.

  Therefore, the composite member obtained by the method of the present invention has excellent mechanical properties (hardness, proof stress, etc.) in the base material (Al alloy member) in addition to high bonding strength.

  After the above-mentioned press-fitting step, although not particularly limited, the mold may be opened after the Al alloy is solidified according to a conventional method, and the composite member may be taken out.

(Surplus part)
The shape of the excess portion is not particularly limited, and may be any shape.
Further, the arrangement of the excess portion is not particularly limited, and may be provided at any position communicating with the cavity. From the viewpoint of preventing the device structure from becoming complicated, it is preferable to provide the device on the lower surface of the lower die as shown in FIG. In addition, a plurality of the excess portions can be provided, but usually the number of the excess portions is preferably one because the device structure becomes complicated.

  Although the volume of the excess portion is not particularly limited, it is preferable that the volume of the excess portion be 3% or more of the volume of the cavity from the viewpoint of enhancing the effect of the press-fitting described above. On the other hand, the upper limit is not particularly limited. However, if the excess portion is too large, the pressure required for press-fitting increases, and a device corresponding thereto is required. Therefore, the volume of the excess portion is 8% or less of the volume of the cavity. It is preferable that

  Next, the present invention will be described more specifically based on examples. The following examples show preferred examples of the present invention, and the present invention is not limited to the examples.

(Example)
According to the above-described embodiment, a composite member including the Cu-based metal member 40 and the Al alloy member 50 having the shape and dimensions shown in FIG. 2 was manufactured. Specifically, first, a copper (C1100) round bar having a diameter of 6 mm and a length of 13 mm was set as an insert in a press die. Next, a semi-solidified Al alloy was supplied into the cavity of the press die and pressed. As the Al alloy, A6061 which is an Al-Mg-Si alloy was used, and the molten metal obtained by melting the Al alloy was semi-solidified while being subjected to electromagnetic stirring.

  By the press, a part of the Al alloy was filled in a surplus portion provided in a press die. Thereafter, the press-fitting plunger was driven to forcibly press-fit the Al alloy filled in the excess portion into the cavity.

  In the obtained composite member, the Cu-based metal member and the Al alloy were firmly joined, and the two did not separate even when a load was applied.

  FIGS. 3A and 3B are micrographs of a joint portion in the composite member obtained in the above example, in which FIG. 3A is a photograph taken at 150 × and FIG. 3B is a photograph taken at 1000 ×. As can be seen from FIG. 3, a layer different from the bulk (base material) portion was formed at the interface between the Cu-based metal member and the Al alloy. When the layer was analyzed by energy dispersive X-ray analysis (EDS), it was found that the layer was a Cu-Al-based alloy layer in which Cu and Al coexisted.

  The thickness of the alloy layer was relatively thick, although it varied depending on the part, and the median of the minimum thickness and the maximum thickness was 1.15 mm.

  Further, the structure of the Al alloy portion was a forged structure as is clear from FIG. Further, when the average particle size (average equivalent circle diameter) of the Al alloy portion was determined by image analysis, it was 50 μm or less.

(Comparative Example 1)
For comparison, a composite member was manufactured using a normal molten metal that was not in a semi-solid state instead of the Al alloy in a semi-solid state. In Comparative Example 1, the press-fitting step was not performed using a mold having no excess portion. Other conditions were the same as those in the above-described embodiment.

FIGS. 4A and 4B are photomicrographs of the joined portion of the composite member obtained in Comparative Example 1, wherein FIG. 4A is a photograph taken at 150 × and FIG. 4B is a photograph taken at 1000 ×. As can be seen from FIG. 4, no alloy layer was formed at the interface between the Cu-based metal member and the Al alloy. Also, the bonding strength between the Cu-based metal member and the Al alloy was inferior to that of the example. When a load of 58.4 N / mm ² was applied, the Cu-based metal member came off the Al alloy member.

(Comparative Example 2)
Further, for comparison, a composite member was manufactured using a mold having no excess portion without performing the press-fitting step. Other conditions were the same as those in the above-described embodiment. The Al alloy was supplied in a semi-solid state as in the example.

  FIGS. 5A and 5B are photomicrographs of the joint in the composite member obtained in Comparative Example 2 described above. FIG. 5A is a photograph taken at 150 × and FIG. 5B is a photograph taken at 1000 ×. As can be seen from FIG. 5, although the alloy layer was formed at the interface between the Cu-based metal member and the Al alloy, the thickness was smaller than that in Example 1, and specifically, the variation due to the portion. However, the median of the minimum and maximum thickness was 0.83 mm. Therefore, the composite member of Comparative Example 2 was inferior in bonding strength as compared with the composite member of Example.

  Further, since the semi-solid metal produced by using electromagnetic stirring was used, the structure of the Al alloy portion was composed of fine particles as shown in FIG. 5B, but the particle shape was substantially spherical. However, it was not a forged structure as in the examples. This is because press-fitting from the surplus portion was not performed. Therefore, the composite member of Comparative Example 2 was inferior in mechanical properties of the Al alloy member portion as compared with the composite member of Example.

10 Lower mold (press mold)
11 Cavity 12 Surplus part 20 Upper die (press die)
Reference Signs List 30 pressurizing device 31 plunger for press fitting 40 Cu-based metal member 50 Al alloy member

Claims (4)

A method for manufacturing a composite member including a Cu-based metal member and an Al alloy member,
Using a press mold having a cavity and a surplus portion communicating with the cavity,
An insert installation step of installing the Cu-based metal member as an insert in the press mold,
In the press die, a semi-solid metal supply step of supplying a semi-solid Al alloy,
A press step of applying pressure to the semi-solidified Al alloy by the press mold to form the cavity shape, and filling a part of the Al alloy in the excess portion.
Press-fitting the Al alloy filled in the excess portion into the cavity.   The method for producing a composite member according to claim 1, further comprising an electromagnetic stirring step of bringing the molten metal obtained by melting the Al alloy into a semi-solid state while applying electromagnetic stirring to the molten metal prior to the semi-solid metal supply step.   The method for manufacturing a composite member according to claim 1, wherein a volume of the excess portion is 3 to 8% of a volume of the cavity. A composite member comprising a Cu-based metal member and an Al alloy member,
The Cu-based metal member and the Al alloy member are joined via a Cu-Al-based alloy layer present at an interface between the Cu-based metal member and the Al alloy member,
A composite member , wherein the Al alloy member has a forged structure composed of flat particles .