JPH08141781A - Joining material for brazing - Google Patents

Abstract

PURPOSE: To provide a joining material capable of securely brazing members to be joined. CONSTITUTION: This joining material for brazing consists of a rare earth element contg. the alloy element AE to induce an eutectic reaction with rare earth elements at AE<=50atm.% and the volumetric fraction Vf of the amorphous phase thereof is Vf>=50%. The liquid phase generated by the joining material exhibits excellent wettability with the members to be joined which are various kinds of materials. The joining material has high oxidation resistance and uniform compsn. according to formation of the amorphous phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a brazing joint material, and more particularly,
The present invention relates to a bonding material made of a rare earth element-based alloy.

[0002]

2. Description of the Related Art For example, a permanent magnet containing a rare earth element is
It is very brittle and has poor machinability, and when exposed to high temperatures, it has a property that the metal structure changes and the magnetic properties deteriorate accordingly.

Therefore, for example, when attaching a permanent magnet to a metal rotor of a motor, it is not possible to adopt attachment means such as an insertion structure, screwing, welding, etc. Therefore, an adhesive has been conventionally used.

[0004]

However, the use of an adhesive causes problems that the adhesive strength is low because the wettability of the permanent magnet is poor, and that the adhesive strength is significantly reduced as the temperature rises. Under such circumstances, it is impossible to meet the demand for high-speed rotation of the motor.

In view of the above, the present invention provides two members to be joined,
For example, it is an object to provide an alloy-based bonding material capable of firmly brazing a metal member.

[0006]

A bonding material for brazing according to the present invention comprises a rare earth element-based alloy containing AE ≦ 50 atom% of an alloying element AE that causes a eutectic reaction with a rare earth element,
It is characterized in that the volume fraction Vf of the amorphous phase is Vf ≧ 50%.

[0007]

Since the rare earth element and the alloy element AE undergo a eutectic reaction during brazing, the temperature at which the joining material is in a liquid phase state or a solid-liquid coexisting state is relatively low. This makes it possible to avoid a change in the characteristics of both members to be joined due to brazing.

On the other hand, the liquid phase generated from the bonding material containing a rare earth element as a main component is highly active and exhibits excellent wettability with respect to members to be bonded made of various materials. The amorphous phase is
Since there is no grain boundary layer that serves as the starting point of oxidation, the oxidation resistance is extremely high, the oxides are rarely mixed, and the composition is uniform without segregation. By using a bonding material having excellent wettability and having a volume fraction Vf of the amorphous phase of Vf ≧ 50% (including 100%), both members to be bonded are firmly brazed. You can

However, if the content of the alloy element AE is AE> 5
When it is 0 atom%, the volume fraction Vf of the liquid phase in the solid-liquid coexisting state becomes low, and the bonding strength decreases. From this, it is desirable that the content of the alloy element AE is set so as to have a eutectic composition or a composition close thereto in relation to the rare earth element.

[0010]

EXAMPLE A rare earth element-based alloy constituting a bonding material is basically composed of a main component rare earth element and an alloy element AE which causes a eutectic reaction with the rare earth element. The rare earth elements are Y, La, Ce, Pr, Nd, Sm, Eu, Gd,
Tb, Dy, Ho, Er, Tm, Yb, Mm (Misch metal), Di (Didym or Didymium) and Lu
It is at least one selected from. In addition, alloy element A
E is Cu, Al, Ga, Co, Fe, Ag, Ni, A
u, Mn, Zn, Pd, Sn, Sb, Pb, Bi, Ge
And at least one selected from In. The content of the alloy element AE is set to AE ≦ 50 atomic%. When two or more alloy elements AE are contained, the total content of them is AE ≦ 50 atom%. In addition, the lower limit of the alloying element is AE in order to secure the liquid phase in the solid-liquid coexisting state.
= 5 atom% is desirable.

Table 1 shows examples of eutectic alloys in rare earth element-based alloys.

[0012]

[Table 1] Examples of the hypoeutectic and hypereutectic alloys in the rare earth element-based alloys include the following. In each chemical formula,
The unit of the numerical value is atomic% (the same applies below). Nd ₆₀
Cu ₄₀ alloy, Nd ₇₅ Cu ₂₅ alloy, Nd ₈₀ Cu ₂₀ alloy, N
d ₅₀ Cu ₅₀ alloy, Nd ₉₀ Al ₁₀ alloy, Nd ₈₀ Co ₂₀ alloy, Sm ₇₅ Cu ₂₅ alloy, Sm ₆₅ Cu ₃₅ alloy, La ₈₅ Ga
₁₅ alloy. Furthermore, as a ternary alloy, Nd ₆₅ Fe ₅ Cu
₃₀ alloy (liquid phase generation temperature 510 ° C) and Nd ₇₀ Cu ₂₅ A
₁₅ alloy (liquid phase generation temperature 474 ° C.) can be mentioned.

In brazing two members to be joined, the two members are superposed with a joining material interposed therebetween, and then the superposed product is placed in a vacuum heating furnace, and the joining material undergoes liquid phase heating under heating. A method is adopted in which the state or the solid-liquid coexisting state is set, and then the furnace is cooled.

During this brazing, the rare earth element and the alloy element A
Since the eutectic reaction occurs with E, the temperature at which the bonding material is in the liquid phase state or the solid-liquid coexisting state is relatively low. As a result, it is possible to avoid changes in the characteristics of the members to be joined due to brazing.

On the other hand, the liquid phase generated from the bonding material containing a rare earth element as a main component is highly active, and exhibits excellent wettability with respect to members to be bonded made of various kinds of materials. The amorphous phase is
Since there is no grain boundary layer that serves as the starting point of oxidation, the oxidation resistance is extremely high, the oxides are rarely mixed, and the composition is uniform without segregation. By using a bonding material having excellent wettability and having a volume fraction Vf of the amorphous phase of Vf ≧ 50% (including 100%), both members to be bonded are firmly brazed. You can

If the heating time t is too long, the characteristics of the members to be joined are changed. Therefore, it is desirable that t≤10 hours, and from the viewpoint of improving productivity, t≤1 hour.

A liquid quenching method, for example, a single roll method is applied to the production of the bonding material. That is, (a) a molten metal having a rare earth alloy composition is prepared. (B) The molten metal is jetted onto the outer surface of the Cu-made cooling roll that rotates at a high speed and is rapidly cooled, whereby the volume fraction Vf of the amorphous phase is Vf ≧.
A thin band-shaped bonding material that is 50% is obtained.

The thickness of the bonding material is controlled by the number of rotations of the cooling roll, the molten metal ejection pressure, the molten metal ejection temperature, etc., and is usually 10 to 150 μm. In this case, the bonding material has a high toughness because it has an amorphous phase, and therefore, it does not break even if formed into a thin strip shape, and is continuously mass-produced.

With the increase in toughness, it is easy to obtain a joining material having a predetermined shape by subjecting the belt-like joining material to punching or the like so as to match the shape of the joining surface of the members to be joined. Example 1 Nd ₇₀ C having a eutectic composition of Nd having a purity of 99.9% and Cu having a purity of 99.9% as shown in FIG.
The u ₃₀ alloy was weighed so as to obtain, then the weighed material was melted using a vacuum melting furnace, and then cast to obtain an ingot.

About 200 g of a raw material was sampled from an ingot made of this Nd ₇₀ Cu ₃₀ alloy, and this was melted at high frequency in a quartz nozzle to prepare a molten metal, and then the molten metal was rotated at a high speed below the slit of the quartz nozzle. Ultra-thin band-like bonding material having a width of 30 mm and a thickness of 70 μm was obtained by jetting it with argon gas pressure onto the outer peripheral surface of the Cu cooling roll and performing ultra-cooling.

The manufacturing conditions in this case are as follows. That is, the inner diameter of the quartz nozzle is 40 mm, the size of the slit is the width
0.25mm, length 30mm, argon gas pressure 1.0kg
f / cm ² , melt temperature 670 ° C., distance between slit and cooling roll 1.0 mm, peripheral speed of cooling roll 20 m / sec
The cooling rate of the molten metal is about 10 ⁵ K / sec.

FIG. 2 shows the X-ray diffraction results of the ingot made of Nd ₇₀ Cu ₃₀ alloy and the band-shaped bonding material. In the band-shaped bonding material, a wide halo pattern was observed at 2θ≈30 °, which indicates that the band-shaped bonding material was obtained. Has an amorphous single-phase structure, and therefore the volume fraction Vf of the amorphous phase is Vf = 100.
%. Further, the band-shaped bonding material had high toughness and was capable of 180 ° contact bending.

In brazing, as shown in FIG. 3, an extremely thin plate-like amorphous bonding material 1 having a length of 10 mm, a width of 10 mm and a thickness of 70 μm was cut out from the band-shaped bonding material.

One member to be joined has a length of 10 mm and a width of 1
0 mm, 3 mm thick NdFeB system permanent magnet (Sumitomo Special Metals Co., Ltd., trade name NEOMAX-28UH) 2 was selected, and the cold-rolled steel plate 4 having a thickness of 0.3 mm was laminated as the other member to be joined. And length 10mm, width 10mm, length 1
A 5 mm rectangular parallelepiped laminate 3 was selected. In this case, the caulking means 5 is used for joining the steel plates 4.

As shown in FIG. 3, one amorphous bonding material 1 is formed on the bonding surface 6 formed by the steel plate end surfaces of one laminated body 3, and one permanent magnet 2 is formed on the amorphous bonding material 1. Further, another amorphous bonding material 1 is further laminated on the permanent magnet 2, and another laminated body 3 is further laminated on the amorphous bonding material 1 with the bonding surface 6 facing downward. The thing was made. Then, the stack is placed in a vacuum heating furnace,
A heating step at a heating temperature T = 530 ° C. and a heating time t = 20 minutes, followed by a cooling step consisting of furnace cooling, is performed so that the permanent magnets 2 are sandwiched by two laminated bodies 3 as shown in FIG. , 3 were brazed through the crystalline bonding layer 7 formed of the amorphous bonding material 1 to obtain a bonded body 8. In this brazing process, the heating temperature T is T = 530 ° C. and exceeds the eutectic point 520 ° C. shown in FIG. 1, so that the amorphous bonding material 1 is in a liquid phase state. The through holes 9 present in both laminates 3 are used for connection with the chuck in the tensile test.

For comparison, a microcap
Nd after cutting with a cutter ₇₀Cu₃₀Better than alloy
10 mm long, 10 mm wide, and 0.25 mm thick (microphone
Manufacture of thin plate-like crystalline bonding material with limit thickness by locator)
Then, using this crystalline bonding material, the same method as described above is performed.
A joined body having the same structure as the joined body 8 shown in FIG.

For comparison, a permanent magnet 2 similar to the above is used for comparison.
And two laminates 3 similar to the above were laminated via an epoxy resin adhesive (manufactured by Nippon Ciba-Geigi Co., Ltd., trade name Araldite) to produce a laminate similar to the above. Then, the stack is placed in a drying oven and heated to a heating temperature of 200
A bonding process similar to the above, in which the two laminated bodies 3 and the permanent magnets 2 are bonded via an epoxy resin adhesive by performing a bonding process consisting of a heating step at a temperature of 60 ° C. for 60 minutes and then furnace cooling It was

A tensile test was conducted on the bonded body 8 using the amorphous bonding material 1, the bonded body using the crystalline bonding material and the bonded body using the epoxy resin adhesive at room temperature and under heating at 150 ° C. As a result, the results shown in Table 2 were obtained.

[0029]

[Table 2] As is clear from Table 2, the bonded body 8 using the amorphous bonding material 1 has higher bonding strength than the bonded body using the epoxy resin adhesive at room temperature and under heating at 150 ° C. The bonding strength was almost the same under both environments, and the variation was small. The jointed body using the adhesive has a low joint strength at room temperature and has a large variation, and the joint strength decreases to one-third of that at room temperature when heated at 150 ° C.

Further, the bonded body 8 using the amorphous bonding material 1 has a higher bonding strength than the bonded body using the crystalline bonding material at the above both temperatures. This is because the amorphous bonding material 1 has excellent oxidation resistance, a small amount of oxide, and a uniform composition.

Further, since the thickness of the amorphous bonding material 1 is less than one third of the thickness of the crystalline bonding material, the amount of corrosion is small and the post-treatment after the brazing treatment is easy. .

The permanent magnet 2 containing a rare earth element such as NdFeB type permanent magnet or SmCo type permanent magnet has its magnetic characteristics, especially coercive force _I H _C (magnetization) when the heating temperature T during the joining process becomes T> 650 ° C. Strength I = 0) tends to decrease.
However, the residual magnetic flux density Br and coercive force _B H _C (magnetic flux density B = 0) Most unchanged, thus the maximum magnetic energy product (BH) max is substantially constant. In the brazing process using the amorphous bonding material 1, the heating temperature T is T = 53.
Since 0 ° C. and T ≦ 650 ° C., the magnetic characteristics of the permanent magnet 2 are not changed.

The poor wettability of the permanent magnet 2 is due to the presence of a rare earth element concentration, that is, a phase having a high Nd concentration in the crystal grain boundaries. In the brazing process using the amorphous bonding material 1, the amorphous bonding material 1 is in a liquid phase state, and Nd whose main component is Nd ₇₀
The liquid phase generated from the Cu ₃₀ alloy exhibits high wettability with respect to the permanent magnet 2 since it is highly active and shares the main component with the phase having a high Nd concentration existing in the crystal grain boundary.
Further, the wettability with respect to the laminated body 3 made of the steel sheet 4 is also very good due to the high activation.

Therefore, the amorphous bonding material 1 as described above is used.
By using, it is possible to firmly bond the permanent magnet 2 and the laminated body 3 without impairing the magnetic characteristics of the permanent magnet 2.

The joining technique is applied to brazing of the permanent magnet 2 to the laminated iron core of the rotor in a motor as a rotary electric machine, and enables realization of a high-speed rotary motor having a rotation speed of 10,000 rpm or more. [Example 2] The same single roll method as in Example 1 was adopted to produce mixed phase bonding materials and amorphous bonding materials of various compositions, and the same brazing treatment as in Example 1 was performed using each bonding material. This was performed to obtain various bonded bodies, and the same tensile test as in Example 1 was performed on each bonded body. Also, similar to Example 1, a crystalline bonding material was manufactured from ingots of various compositions and compared.

Table 3 shows the brazing treatment conditions such as the composition of various joining materials and the joining strength of the joined body.

[0037]

[Table 3] In Table 3, Example 1 of the joining material is a multi-phase joining material having a metal structure composed of a mixed phase of an amorphous phase and a crystalline phase, and the volume fraction Vf of the amorphous phase is 75%. , Vf ≧ 50%
Since the above condition is satisfied, the composition is more uniform than that of the crystalline bonding material of Example 1a, and as a result, the bonding strength of the bonded body is increased. In addition, Examples 2 and 3 of the bonding material are both amorphous bonding materials, while Examples 2a and 3a of the bonding material are both crystalline bonding materials. Also in this case, it is understood that good results can be obtained by using the amorphous bonding materials 2 and 3.

The joining material is also used for brazing a metal member other than the permanent magnet to another metal member.

[0039]

According to the present invention, by providing the above-specified structure, it is possible to firmly braze two members to be joined by generating a liquid phase in a relatively low temperature range. A bonding material can be provided.

In particular, this bonding material has an advantage that the bonding strength can be increased without deteriorating the magnetic characteristics of the permanent magnet in the bonding of the permanent magnet containing the rare earth element and the dissimilar metal member by selecting the composition thereof. Have.

[Brief description of drawings]

FIG. 1 shows a main part of a Cu—Nd system phase diagram.

FIG. 2 is an X-ray diffraction diagram for a band-shaped bonded body and an Nd ₇₀ Cu ₃₀ alloy ingot.

FIG. 3 is a perspective view showing a superposition relationship between a laminated body and a bonding material.

FIG. 4 is a perspective view of a joined body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bonding material 2 Permanent magnet 3 Laminated body 7 Bonding layer 8 Bonded body

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[Procedure amendment]

[Submission date] January 23, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

A liquid quenching method, for example, a single roll method is applied to the production of the bonding material. That is, (a) a molten metal having a rare earth element alloy composition is prepared. (B)
The molten metal is jetted onto the outer surface of the Cu-made cooling roll that rotates at a high speed to perform ultra-quench cooling, whereby the volume fraction Vf of the amorphous phase is V
A thin band-shaped bonding material with f ≧ 50% is obtained.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

[0037]

[Table 3] In Table 3, Example 1 of the joining material is a multi-phase joining material having a metal structure composed of a mixed phase of an amorphous phase and a crystalline phase, and the volume fraction Vf of the amorphous phase is 75%. , Vf ≧ 50%
Since the above condition is satisfied, the composition is more uniform than that of the crystalline bonding material of Example 1a, and as a result, the bonding strength of the bonded body is increased. In addition, Examples 2 and 3 of the bonding material are both amorphous bonding materials, while Examples 2a and 3a of the bonding material are both crystalline bonding materials. Also in this case, it can be seen that good results can be obtained by using Examples 2 and 3 of the amorphous bonding material.

Claims (4)

[Claims] 1. A rare earth element-based alloy containing AE ≦ 50 atomic% of an alloying element AE that causes a eutectic reaction with a rare earth element, and a volume fraction Vf of an amorphous phase is Vf ≧ 50%. Bonding material for brazing. 2. The alloy element AE is Cu, Al, Ga,
Co, Fe, Ag, Ni, Au, Mn, Zn, Pd, S
The brazing material for brazing according to claim 1, which is at least one selected from n, Sb, Pb, Bi, Ge and In. 3. The brazing joint material according to claim 1, wherein the rare earth element-based alloy has a eutectic composition. 4. The brazing joint material according to claim 1, which is used for joining a permanent magnet containing a rare earth element and a dissimilar metal member.