JP2000237863A - Formation of metallic interface reaction layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the control of thickness while forming a reaction layer in the interface between a first metal and a second metal member by allowing the solid second metal member to contact with the molten first metal surface and also, solidifying the molten metal while oscillating the second metal member with the propagation of ultrasonic wave. SOLUTION: As the first metal, e.g. Mg or Mg alloy is used and the solid second metal member e.g. Al alloy, is brought into contact with the molten first metal surface and the molten first metal is solidified while oscillating the second metal member with the propagation of the ultrasonic wave. Further, the interface reaction layer is discovered on the first metal surface by separating the second metal member from the first metal during solidifying. Then, the interface reaction layer formed on the first metal surface can be utilized as the surface hardened layer by suitably selecting the kinds of the first metal and the second metal member. A crucible 6 charging ADC12, is heated in a prescribed condition, and when the molten metal becomes a prescribed temp. after forcibly air-cooling, the tip part of the metal bar 5 of SUS304 is dipped into the molten metal, and the ultrasonic wave oscillation under a prescribed condition is applied to obtain the joined part of both metals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for forming a metal interface reaction layer. The method for forming a metal interfacial reaction layer of the present invention can be used for forming a surface hardened layer or for forming an interfacial reaction layer at the interface between a cast-in member and a casting at the time of cast-in casting.

[0002]

2. Description of the Related Art For example, since an aluminum alloy is active and has a low softening temperature, it is necessary to form a protective layer on the surface for use in a sliding environment or a high-temperature corrosive environment. In order to form the protective layer, methods such as surface coating such as plating and thermal spraying, surface alloying, partial compounding, joining and casting are known.

[0003] In this insert casting, it is known that an interface reaction layer may be formed at the interface between the insert member and the casting, and it has been studied to use this interface reaction layer as a bonding layer or the like. ing. For example, see
No. 280110 discloses a method in which a surface hardened layer is formed by irradiating the surface of an aluminum member with a high-density energy beam such as a laser beam or an electron beam, followed by rapid solidification.

[0004]

However, the surface hardening method using a high-density energy beam requires a large-scale apparatus, which increases facility costs and limits installation space. Also, in cast-in-place casting, for example, when trying to cast a cast-in stainless steel member with molten aluminum, if the temperature of the molten metal is low, the bonding becomes poor due to the oxide film, and if the temperature of the molten metal is high, a thick reaction layer is generated at the interface. It is known that there is a problem that the bonding strength is reduced.

The present invention has been made in view of such circumstances, and has as its object to enable easy formation of an interface reaction layer and control of the thickness of the interface reaction layer.

[0006]

According to the present invention, there is provided a method for forming an interface reaction layer, comprising the steps of: bringing a solid second metal member into contact with a surface of a molten metal of a first metal; An object of the present invention is to form a reaction layer at an interface between a first metal and a second metal member by solidifying a molten metal while vibrating the members.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is characterized in that a solid second metal member is brought into contact with the surface of a first molten metal while being subjected to ultrasonic vibration. Thereby, an interface reaction layer is formed at the interface between the two. For example, the interface reaction layer is not formed only by bringing the second metal member made of stainless steel into contact with the first metal melt made of aluminum, but the second metal member comes into contact with the first metal melt surface while being ultrasonically vibrated. By doing so, an interface reaction layer can be formed. Although the reason for this has not been clarified at present, it is considered that the reason is that the oxide film and the air layer at the interface are removed by the ultrasonic vibration.

In the case of forming a surface hardened layer according to the present invention, a solid second metal member is brought into contact with the surface of the molten metal of the first metal, and the molten metal is solidified while vibrating the second metal member by propagation of ultrasonic waves. Let it. Thereby, the oxide film and the air layer at the interface are removed, and the interface reaction layer is formed. Then, by separating the second metal member from the first metal during solidification, an interface reaction layer appears on the surface of the first metal. Further, after the first metal is solidified, cutting may be performed at the interface so that the interface reaction layer is exposed. By appropriately selecting the types of the first metal and the second metal member, the interface reaction layer exposed on the first metal surface can be used as a surface hardened layer.

For example, if magnesium or a magnesium alloy is used as the first metal and a member made of an aluminum alloy is used as the second metal member, an interface reaction layer made of spinel (MgAl ₂ O ₄ ) can be formed at the interface. By removing the aluminum alloy member, the interface reaction layer can be used as a surface hardened layer. If aluminum or an aluminum alloy is used as the first metal and a stainless steel member made of SUS304 is used as the second metal member, Fe-Al-Si, Al ₉₅
An interface reaction layer made of Fe ₄ Cr, Cr ₃ Ni ₅ Si ₂ or the like is formed, and the interface reaction layer can be used as a surface hardened layer by removing the stainless steel member.

[0010] Further, by controlling the temperature of the first molten metal at the time of ultrasonic vibration, it is possible to avoid joining the second metal member while forming an interface reaction layer. With this configuration, the step of removing the second metal member described above can be omitted, and the formation of the surface hardened layer is further facilitated. Since the interface reaction layer is formed only on the surface where the second metal member contacts, if the area of the contacting portion of the second metal member is reduced, the surface hardened layer can be partially formed.

Further, according to the method for forming an interface reaction layer of the present invention, the thickness of the interface reaction layer can be easily controlled. When the second metal member is brought into contact with the first molten metal, an interface reaction layer may be formed without applying ultrasonic vibration.
The thickness of the interface reaction layer is proportional to the temperature of the melt, and the interface reaction layer grows as the contact time with the melt increases. However, in the case of cast-in-place casting, if the interface reaction layer is excessively thick, physical properties such as bonding strength may be reduced in the case of cast-in-place casting.

Therefore, in the present invention, the second metal member is brought into contact with the first molten metal while being subjected to ultrasonic vibration. Then, it became clear that the interfacial reaction layer generated on the surface of the second metal member was scattered in the molten metal due to the acoustic current generated by the ultrasonic vibration, thereby reducing the thickness of the interfacial reaction layer. An interface reaction layer is instantaneously formed by contact with the molten metal while being subjected to ultrasonic vibration, and thereafter, the longer the vibration time, the thinner the interface reaction layer becomes, and the larger the total amplitude of the ultrasonic vibration becomes, the larger the interface reaction layer becomes. It became clear that the thickness of the reaction layer was reduced. However, if the vibration time is too long, cracks may occur in the interface reaction layer.

That is, by adjusting the ultrasonic vibration time and the total amplitude, it is possible to control the thickness of the interface reaction layer, and to avoid problems such as a decrease in cast joining strength in the insert casting. In the casting joining with ultrasonic vibration, first, an air layer and an oxide film at the interface are removed by ultrasonic vibration, and then an interface reaction layer is formed. Therefore, in order to reduce the thickness of the interface reaction layer, it is most desirable to solidify at the moment when the surface reaction layer is formed by removing the interface air layer or oxide film.

On the other hand, for example, when the second metal member is brought into contact with the first molten metal while being vibrated by ultrasonic waves and pulled up in this state, the first molten metal adheres to the surface of the second metal member so as to be attracted thereto. It became clear that the amount of adhesion was larger than when no ultrasonic vibration was applied. That is, it became clear that the ultrasonic vibration increases the adhesive force. Also, the amount of the adhered molten metal is slight even if the amount of the adhered metal is increased, and the molten metal is rapidly solidified on the surface of the pulled up second metal member.

Therefore, if this phenomenon is utilized, an extremely thin interface reaction layer can be formed at the interface between the pulled-up second metal member and the first molten metal adhered thereto. That is, when the second metal member is brought into contact with the first molten metal while being ultrasonically vibrated and pulled up, an appropriate amount of the first molten metal adheres to the second metal member in a state where the interface reaction layer is formed. I have. Then, the deposited molten metal is cooled and solidified at the moment of being pulled up, so that the growth of the interface reaction layer is suppressed and a thin interface reaction layer is formed.

Then, if the second metal member to which the solidified material of the first molten metal adheres is immersed in the first molten metal again, the solidified material of the first molten metal and the first molten metal are cast and joined, and the solidification is performed. Bonding can be easily performed between the object and the second metal member while maintaining a thin interface reaction layer. Also in this case, it is desirable to perform ultrasonic vibration for the purpose of removing the oxide film. It is desirable that the temperature of the molten metal be as low as possible and the vibration time be as short as possible so that the coagulated material does not melt again and the interface reaction layer grows.

[0017]

(Embodiment 1) In this embodiment, the present invention is applied to a case where a hardened surface layer is formed on the surface of an aluminum alloy. FIG. 1 shows an ultrasonic casting and joining apparatus used in the present embodiment. This apparatus includes an ultrasonic oscillation source 1, a vibrator 2 having air cooling means (not shown), a horn 3 having water cooling means (not shown), and a heating furnace 4. The resonance frequency of this vibration system is 20 kilohertz.

In this embodiment, a SUS3
A metal rod 5 made of 04 and having a diameter of 9 mm is fixed via a nut 30. In addition, a crucible 6 is arranged in the heating furnace 4,
The crucible 6 has an ADC 12 of an Al-Si-Cu alloy.
Is inserted. First, the crucible 6 was heated in the heating furnace 4, and the ADC12 melt was held at 973K for 20 minutes.
Subsequently, the heating furnace 4 was removed and forced air cooling was performed. The crucible 6 was raised by the lift 7 at the same time when the temperature of the molten metal reached 913 K, and the tip 1 mm of the metal rod 5 was immersed in the molten metal as shown in FIG. Immediately before immersion in the molten metal,
Ultrasonic vibration was started at 0 μm, and after 10 seconds, ultrasonic vibration was stopped. After that, forced air cooling was continued.

The metal rod 5 and A of the sample cooled to room temperature
Microstructure photograph of the cross section of the junction of DC12 and EPM at the interface
A analysis results are shown in FIGS. 2 and 3, respectively. (Example 2) Cast joining was performed in the same manner as in Example 1 except that the temperature of the molten metal when the metal rod 5 was immersed in the molten metal was 933K. A micrograph of the cross section of the joint between the metal rod 5 and the ADC 12 of the sample cooled to room temperature, and EP at the interface.
MA analysis results are shown in FIGS. 4 and 5, respectively.

(Comparative Example 1) Using the same apparatus as in Example 1, the heating furnace 4 was removed and forced air cooling was performed.
At the same time as the temperature reached 3K, the crucible 6 was raised by the lift 7 and the tip 1 mm of the metal rod 5 was dipped in the molten metal. Forced air cooling was performed without ultrasonic vibration. FIGS. 6 and 7 show a micrograph of the cross section of the joint between the metal rod 5 and the ADC 12 and the EPMA analysis result of the interface of the sample cooled to room temperature, respectively.

(Evaluation) In the joint sample obtained by the method of Comparative Example 1, the metal rod 5 was not joined as shown in FIG. 6, and it was difficult to join even if the temperature of the molten metal was increased to 953K. Was. From FIG. 7, it is clear that a large amount of oxygen is observed on the surfaces of the metal rod 5 and the ADC 12, and that the bonding was inhibited by the oxide film. No interface reaction layer was formed at the interface of the joined sample obtained by the method of Comparative Example 1.

On the other hand, in the bonded sample obtained by the method of the first embodiment, a gap is partially formed as shown in FIG. 2 and partially bonded, and in the method of the second embodiment, the interface is formed as shown in FIG. Are in close contact and are joined over the entire surface. Since the difference between Example 1 and Example 2 is only the molten metal temperature at the time of joining, it is considered that there was a difference in the joining state depending on the molten metal temperature. And Example 1
In the partially bonded sample, a large amount of oxygen is recognized at the interface as shown in FIG. 3, and in Example 2, almost no oxygen is recognized at the interface as shown in FIG. Therefore, it is considered that the cast joining of the SUS 304 and the ADC 12 is realized by removing the oxide film at the joining interface by ultrasonic vibration.

In Examples 1 and 2, 51% A
1-24% Fe-12% Mn-5.8% Si-4.5%
An interfacial reaction layer composed of Cr is formed. This interface reaction layer has a hardness of about 1000 HV,
Much higher hardness. Therefore, if the metal bar 5 is removed by cutting or the like, an interface reaction layer having high hardness remains on the surface of the ADC 12 and is exposed, and can be used as a surface hardened layer. Further, the joined sample obtained by the method of Example 1 has an advantage that the metal rod 5 can be easily removed due to the existence of a partial gap.

By the way, in Example 1, the interface reaction layer was about 1
In the second embodiment, an interface reaction layer having a thickness of about 5 μm, which is thinner than that of the first embodiment, is formed. This is due to the effect of the temperature of the molten metal at the start of joining. Thus, the relationship between the temperature of the molten metal and the thickness of the formed interface reaction layer was determined by experiment, and the results are shown in FIG. White circles indicate that the entire surface is completely joined, semi-white semi-black circles are partially joined,
Black circles indicate that they are not joined. As shown in FIG. 8, in the case where the ultrasonic vibration was not applied, even if the temperature of the molten metal was high, the interface reaction layer was not formed and was not joined. This is because an oxide film exists at the interface.

On the other hand, when ultrasonic vibration is applied, if the bonding temperature is, for example, about 900 K, an interface reaction layer is formed even without bonding. Therefore, a bonding temperature of about 9
If the temperature is set to 00K, the surface hardened layer can be formed without the need for the metal rod removing step. However, in FIG. 8, the thickness of the surface hardened layer greatly varies depending on the conditions. Therefore, an experiment described in the following example was performed.

Example 3 First, the crucible 6 was heated in the heating furnace 4 and the ADC12 melt was held at 973K for 20 minutes. Subsequently, the heating furnace 4 was removed and forced air cooling was performed. The crucible 6 was raised by the lift 7 at the same time when the temperature of the molten metal reached 923 K, and the tip 1 mm of the metal rod 5 was immersed in the molten metal.
Immediately before immersing in the molten metal, the metal rod 5 starts to be subjected to ultrasonic vibration,
After vibrating for 4 seconds, the ultrasonic vibration was stopped. Then 3.3
Forced air cooling was continued at a cooling rate of K / sec.

The obtained bonded sample was in a partially bonded state as in Example 1 as shown in FIG. 9, and the thickness of the interface reaction layer was 4.5 μm. (Example 4) It is the same as Example 3 except that the ultrasonic vibration was changed to 10 seconds instead of 4 seconds.

The obtained sample is in a state of being closely bonded as shown in FIG. 10, and the thickness of the interface reaction layer is 1
In the solidified ADC 12, particles having the same composition as that of the interface reaction layer exist. (Evaluation) That is, in the method of Example 4, since the excitation time was longer than that of Example 3, it was considered that the formed interface reaction layer was scattered into the molten metal by acoustic flow, and the interface reaction layer was thinned accordingly. . Therefore, it is clear that the thickness of the interface reaction layer can be controlled by controlling the ultrasonic vibration time.

FIG. 8 shows that the interface reaction layer formed by the ultrasonic vibration is thick in the case of non-joining and partial joining,
It can be seen that in the case of close contact bonding, the thickness is temporarily reduced and the thickness increases as the bonding temperature increases. Therefore, in the case of forming an intimate bond, it is particularly preferable if the molten metal solidifies once the thickness of the interface reaction layer is once reduced, since the thickness of the interface reaction layer can be extremely reduced.

According to the study of the present inventors, when the second metal member is brought into contact with the first molten metal while being vibrated by ultrasonic waves, and pulled up in that state, the first molten metal is brought to the surface of the second metal member. It was found that the particles adhered so that they adhered, and the amount of adhesion was larger than in the case where no ultrasonic vibration was applied. It is presumed that this phenomenon is also due to the removal of the air layer existing at the interface.

Therefore, in the following embodiment, casting and joining are performed in two steps. (Example 5) <First step> First, the crucible 6 was heated in the heating furnace 4 and the ADC12 melt was held at 973K for 20 minutes. Subsequently, the heating furnace 4 was removed and forced air cooling was performed. Melt temperature is 9
The crucible 6 was raised by the lift 7 at the same time when the temperature reached 23 K, and the tip 1 mm of the metal rod 5 was immersed in the molten metal. Metal rod 5
Immediately before being immersed in the molten metal, ultrasonic vibration was started at a total amplitude of 13 μm, and after being vibrated for 10 seconds, the crucible 6 was lowered. Then, while continuing the ultrasonic vibration, the molten metal attached to the tip of the metal rod 5 was rapidly solidified.

At this time, the thickness of the adhesion layer is about 4 μm,
At the interface between the adhesion layer and the metal rod 5, as shown in FIG.
An interface reaction layer having a thickness of about 1.5 μm similar to that in Example 4 was formed. In addition, particles scattered from the interface reaction layer exist in the adhesion layer. <Second Step> Next, when the temperature of the molten metal is 873K, the crucible 6 is raised, and the tip of the metal rod 5 having the adhesion layer is 1 mm.
Was soaked in the molten metal. Ultrasonic vibration of the metal rod 5 was started at a total amplitude of 10 μm immediately before being immersed in the molten metal, and ultrasonic vibration was stopped after vibrating for 4 seconds. Thereafter, forced air cooling was continued at a cooling rate of 3.3 K / sec.

In this second step, the air layer and the oxide film at the interface between the adhesion layer and the molten metal are removed by ultrasonic vibration, and then the adhesion layer is slightly melted and melt-bonded to complete the bonding. As shown in FIG. 12, the obtained bonded sample is in a state of being closely bonded and bonded, and the thickness of the interface reaction layer is about 1.5 μm, and the thickness obtained in the first step is maintained.
In the solidified ADC 12, a Si phase crystallized from the scattered interface reaction layer is present in a granular form.

Therefore, also in this embodiment, a thin interface reaction layer can be easily formed.

[0035]

According to the method for forming a metal interfacial reaction layer of the present invention, an interfacial reaction layer between metal species, which has been conventionally difficult, can be reliably formed. It is also easy to control the thickness of the interface reaction layer. Therefore, the joining strength in cast joining can be improved, and a hardened surface layer can be formed without using a high-density energy beam or the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an ultrasonic casting apparatus used in an embodiment of the present invention.

FIG. 2 is a photomicrograph showing the metal structure at the interface of the cast joint obtained in one example of the present invention.

FIG. 3 is an EPMA analysis chart of an interface of a cast joint product obtained in one example of the present invention.

FIG. 4 is a micrograph showing the metal structure of the interface of the cast joint obtained in the second embodiment of the present invention.

FIG. 5 is an EPMA analysis chart of the interface of the cast joint product obtained in the second example of the present invention.

FIG. 6 is a photomicrograph showing the metal structure of the interface of the cast joint obtained in the comparative example of the present invention.

FIG. 7 is an EPMA analysis chart of an interface of a cast joint product obtained in a comparative example of the present invention.

FIG. 8 is a graph showing the relationship between the temperature of the molten metal at the time of joining and the thickness of the interface reaction layer.

FIG. 9 is a photomicrograph showing the metal structure at the interface of the cast joint obtained in the third example of the present invention.

FIG. 10 is a photomicrograph showing the metal structure at the interface of the cast joint obtained in the fourth example of the present invention.

FIG. 11 is a photomicrograph showing the metal structure at the interface of the cast joint obtained in the first step of the fifth example of the present invention.

FIG. 12 is a photomicrograph showing the metal structure of the interface of the cast joint obtained in the second step of the fifth example of the present invention.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 20, 1999 (1999.12.
20)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9

[Procedure amendment 5]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 10

[Procedure amendment 6]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 11

[Procedure amendment 7]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG.

Claims (1)

[Claims] 1. A method in which a solid second metal member is brought into contact with the surface of a molten metal of a first metal, and the molten metal is solidified while vibrating the second metal member by propagation of ultrasonic waves, thereby forming the first metal and the first metal. A method for forming a metal interface reaction layer, comprising forming a reaction layer at an interface with a second metal member.