KR100787929B1 - Method of low temperature joining between ti-cu dissimilar metals using amorphous filler material - Google Patents

Abstract

A method for low temperature bonding between Ti-Cu dissimilar metals using an amorphous insert material is provided to obtain a preferable effect in the internal thermal stress aspect without affecting mechanical properties of a surrounding base metal, simply perform bonding and welding processes without pre-heat and post-heat treating processes, and make it possible for the method to be usefully used in bonding of dissimilar metals or alloys of various parts. A method for low temperature bonding between Ti-Cu dissimilar metals using an amorphous insert material comprises the steps of: positioning an amorphous insert material(B) with a low melting point between Ti(A2) and Cu(A1) to be joined with each other; and heating the Ti and Cu to at least the melting point of the amorphous insert material inserted between the Ti and Cu, thereby bonding the Ti and Cu with each other. The amorphous insert material with a low melting point is an alloy comprising Ti and Cu to be joined with each other. The amorphous insert material with a low melting point is an alloy comprising 30 to 50 atomic % of Ti, 5 to 25 atomic % of Cu, 1 to 20 atomic % of Ni and 15 to 35 atomic % of Be. The amorphous insert material with a low melting point is formed in a form selected from the group consisting of powder, ribbon and sheet.

Description

Method for low temperature joining between Ti-Cu dissimilar metals using amorphous filler material

1 is a schematic diagram of a low-temperature bonding method between titanium-copper dissimilar metal using an amorphous insert according to the present invention,

2 is a scanning electron micrograph (maintenance temperature: 690 ℃) showing the surface of the titanium-copper bonded to the bonded according to an embodiment of the present invention,

3 is a scanning electron micrograph (maintenance temperature: 760 ℃) showing the surface of the titanium-copper bonded to the bonded according to an embodiment of the present invention,

Figure 4 is a scanning electron micrograph (maintenance temperature: 790 ℃) showing the surface of the titanium-copper bonded to the bonded according to an embodiment of the present invention.

<Short Description of Main Reference Signs>

A1: copper

A2: titanium

B: low melting point amorphous insert

C1: heating means

C2: heating means

The present invention relates to a low temperature bonding method between titanium-copper dissimilar metal using an amorphous insert.

Current architecture; Structures including transportation equipment such as automobiles, ships, airplanes, and trains; Various piping; And pipes, etc., there are many component parts that require joining between metals or alloys. Most of the welding between the metal and the alloy is a welding method using a high temperature melt bonding.

However, melt bonding and welding have a problem of deteriorating the mechanical properties by changing the structure of the surrounding base material such as grain coarsening due to the high working temperature, and stress corrosion cracking (SCC) due to internal stress formation by high temperature treatment. It is causing a problem. In addition, during melt bonding and welding, pre and post heat treatment is required to control the structure and remove residual stress. For this pre and post heat treatment, complicated heating / maintenance and precise control of the cooling rate are required, thereby reducing the cost of joining and welding. In addition to increasing, there is a difficulty in securing the reliability of the joint and the weld. Furthermore, melt bonding and welding are difficult to apply to heterojunctions between different metals or different compositions.

Therefore, it is recognized that there are no semi-permanent, field-applicable and practical countermeasures for dissimilar metals, especially in the case of structures requiring dissimilar metals, differences in melting points and coefficients of thermal expansion between dissimilar metals, or internal stress formation due to high temperature heat treatment. Due to this, there have been many difficulties in the application of the existing high temperature liquid melt welding technology (TIG, SMAW, etc.). Therefore, there is always a risk of fragile interface formation, stress corrosion cracking, corrosion and leakage by applying a process that mainly depends on mechanical physical contact at the contact area.

In light of these considerations, development of sound bonding technology that provides sufficient tensile strength and adhesive strength between the dissimilar metals / alloys of various structural components, and excellent leak tight characteristics and is applicable in the field is required. Low-temperature solid-state bonding technique using non-melting method is considered suitable without causing deterioration of tissue and unhealthy internal stress.

Representative solid-state welding technologies that have been recently developed include friction welding (friction pressure welding, friction stir welding) and brazing. The research on friction bonding has been increasing rapidly since the 1990s, but it is applicable only to the joining of plates or the joining of materials with circular cross-sections due to the limited shape of the joinable materials. Recently, the research on brazing technology has been actively conducted to apply to new materials such as ceramics and high temperature materials. However, the results of the previous studies show that the brazing temperature is higher than the liquidus line of the intercalating metal so that the base material to be bonded has a large heat effect. The problem which causes the characteristic fall of is shown. For example, the bonding temperature between titanium so far is about 900-1000 ° C., which is higher than the α-β transformation temperature of titanium, indicating a problem that changes in the properties of the titanium base material to be bonded at the time of bonding occur. In addition, research on brazing so far has focused only on bonding between homogeneous metals (for example, titanium-titanium bonding), and the development of bonding technology on brazing between dissimilar metals such as titanium-copper has significantly different characteristics. It is a weak situation.

To solve this problem, Shiue et al. Performed a titanium-copper heterojunction using a crystalline silver insert [R.K. Shiue et. Al., “The interfacial reaction of infrared brazing Cu and Ti with two silver-based braze alloys”, Journal of Alloys and Compounds, 371 (2004) 148-157]. There is a problem of changing the titanium base material at the time of bonding.

Accordingly, the present inventors have solved the problem of the conventional melt bonding technology and at the same time, while studying a method of performing a bonding between different metals having a significant difference between the two metals such as titanium-copper at low temperature, low melting point amorphous insertion The ash was placed between dissimilar metals and elevated above the melting temperature of the low melting point amorphous insert to develop a method of forming dissimilar metals and completed the present invention.

It is an object of the present invention to provide a low temperature bonding method between titanium and copper dissimilar metals using a low melting point amorphous insert.

In order to achieve the above object, the present invention

Placing a low melting amorphous insert between the titanium and copper to be joined (step 1); And

It provides a low-temperature bonding method between titanium and copper dissimilar metals using a low melting point amorphous insert comprising the step (step 2) of heating a temperature above the melting temperature of the low melting point amorphous insert inserted in step 1 (step 2). do.

Hereinafter, the present invention will be described in detail with reference to FIG. 1 .

1 is a schematic diagram showing a low temperature bonding method between a dissimilar metal of titanium and copper according to the present invention.

As shown in FIG . 1 , a low melting point amorphous insert B is first positioned between titanium (A2) and copper (A1) to be bonded.

The low melting amorphous insert is made of an amorphous alloy. It can be manufactured for most alloy materials (Fe-based, Ti-based, Ni-based). The amorphous alloy has a composition close to the eutectic composition for amorphous formation, and its melting temperature is significantly lower than that of the general crystalline alloy. Therefore, when used as a brazing insert, the temperature for joining two base materials is conventionally brazed. Can be significantly lower than the temperature. In addition, due to the composition close to the process composition, the melting temperature range is narrow, the insert can be melted quickly in a short time to form a bonding time can be reduced.

In the low temperature bonding method of the dissimilar metal according to the present invention, the low melting point amorphous insert is preferably an alloy containing titanium and copper to be bonded. For example, such low melting amorphous inserts may use alloys containing 30-50 atomic% zirconium, 5-25 atomic% titanium, 5-25 atomic% copper, 1-20 atomic% nickel and 15-35 atomic% beryllium. Can be. In addition, the solidus temperature of the low melting point amorphous insert can be used that is 670 ℃ or less, the liquidus temperature is 730 ℃ or less. Since such low melting amorphous inserts are in an equilibrium state, the two-metal dissimilar metals to be bonded are contained in large amounts, thereby facilitating dissimilar metal bonding.

In the low temperature bonding method between dissimilar metals according to the present invention, the low melting point amorphous insert may be in the form of powder, ribbon, plate, or the like, but is not limited thereto.

In the low temperature bonding method between dissimilar metals according to the present invention, the method for locating the low melting point amorphous insert is not particularly limited, and for example, after placing the low melting point amorphous insert on titanium or copper, The method of placing a metal thereon, and coating the low melting point amorphous insert on titanium or copper can be used.

After placing the low melting point amorphous insert (B) between the titanium (A2) and copper (A1), the amorphous insert (B) and the ambient temperature by using the heating means (C1, C2), the amorphous insert (B) When the temperature is raised above the melting temperature and maintained for a predetermined time, diffusion of alloying elements occurs due to the difference in composition between the molten amorphous insert (B), titanium (A2) and copper (A1). A strong bond can be made between (B) and titanium (A2) and copper (A1).

In the low temperature bonding method between dissimilar metals according to the present invention, the bonding temperature is preferably 670 ~ 1085 ℃. This is because the solidus temperature of the low melting point amorphous insert is 670 ° C or lower, and the melting point of copper is 1085 ° C. Therefore, the bonding method of the present invention does not affect the physical properties of the base material because it can be bonded even at a temperature much lower than the conventional brazing temperature (900 ~ 1000 ℃) (900 ℃ or less). In addition, it can bring about a very desirable effect in terms of internal thermal stress, and can greatly contribute to the simplification of the joining and welding process because it does not have to perform the pre- and post-heat treatment process that requires complex and precise thermal history control.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only examples of the present invention, and the scope of the present invention is not limited to the following examples.

< Example  1> Amorphous Inserts  Titanium-copper heterogeneous Intermetallic  Low temperature bonding

A low melting point amorphous insert between a titanium metal plate having a melting temperature of 1160 ° C. and a copper metal plate having a melting temperature of 1083 ° C. with 41.2 atomic% zirconium, 13.8 atomic% titanium, 12.5 atomic% copper, 10.0 atomic% nickel, and 22.5 atomic% beryllium. After inserting a ribbon having a thickness of 60 μm, infrared brazing was performed while raising the temperature at a rate of 100 ° C./min until the temperature became 690 ° C. in an argon atmosphere. The temperature was maintained at 690 ° C. for 10 minutes, followed by cooling at an average cooling rate of 50 ° C./minute to bond titanium and copper.

< Example  2> Amorphous Inserts  Titanium-copper heterogeneous Intermetallic  Low temperature bonding

Titanium and copper were bonded in the same manner as in Example 1 except that the temperature was raised to 760 ° C.

< Example  3> Amorphous Inserts  Titanium-copper heterogeneous Intermetallic  Low temperature bonding

Titanium and copper were bonded in the same manner as in Example 1 except that the temperature was raised to 790 ° C.

< Experimental Example > Bonded Surface Analysis

In order to determine the compactness of the titanium-copper bonded by the bonding method according to the present invention was carried out the following experiment.

After observing the microstructure of the titanium-copper junctions bonded according to Examples 1 to 3 with a scanning electron microscope, the results are shown in FIGS. 2 to 4 .

As shown in FIGS . 2 to 4 , even when the titanium-copper heterojunction is performed at a low temperature of 900 ° C. or less by using a low melting point amorphous insert, a dense joint without cracks or pores may be formed at the joint. have. In addition, the diffusion of the alloying element due to the difference in composition between the molten amorphous insert and titanium and copper at the time of bonding can be confirmed that the strong bonding between the titanium and copper accordingly. Diffusion occurred due to the diffusion of titanium and copper into the molten low melting point amorphous insert, and the junction was formed to form a crystalline structure instead of an amorphous structure. In addition, it can be seen that the diffusion layer of the component element is formed at the interface between the junction and titanium and copper, it can be confirmed the compactness of the titanium-copper heterojunction.

As described above, the joining method according to the present invention is simple in various forms between the titanium-copper dissimilar metals / alloys to which the joining temperature is much lower than the conventional brazing temperature (below 900 ° C.) and the low melting point amorphous insert is to be joined. Because of the positioning and bonding, it can have a very desirable effect in terms of internal thermal stress without affecting the mechanical properties of the surrounding base material, and it is not necessary to perform the pre and post heat treatment process that requires complicated and precise thermal history control. It can also contribute greatly to the simplification of the welding process procedure. In addition, since there is little material dependency, it can be usefully used for dissimilar metal / alloy joining of various component materials.

Claims (7)

Placing a low melting amorphous insert between the titanium and copper to be joined (step 1); And A low-temperature bonding method between titanium and copper dissimilar metals using a low melting amorphous insert comprising a step (step 2) of bonding titanium and copper by heating above the melting temperature of the low melting amorphous insert inserted in step 1. 2. The method of claim 1, wherein the low melting amorphous insert is an alloy comprising titanium and copper to be bonded. 3. The method of claim 1, wherein the low melting amorphous insert comprises 30 to 50 atomic% zirconium, 5 to 25 atomic% titanium, 5 to 25 atomic% copper, 1 to 20 atomic% nickel and 15 to 35 atomic% beryllium A low temperature bonding method between titanium and copper dissimilar metals using a low melting point amorphous insert, which is an alloy. The method of claim 1, wherein the low melting point amorphous insert is any one selected from the group consisting of a powder, a ribbon, and a plate. 2. The low melting amorphous insert of claim 1, wherein the low melting amorphous insert is positioned on titanium or copper by a method of positioning the low melting point amorphous insert, and then another metal is placed thereon. Low temperature bonding method between titanium and copper dissimilar metal using ash. The method of claim 1, wherein the low melting point amorphous insert is coated with titanium or copper by a method of locating the low melting point amorphous insert. . The low temperature bonding method between titanium and copper dissimilar metals using a low melting point amorphous insert according to claim 1, wherein the bonding temperature is 670 to 1085 ° C.

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