JPH0798210B2 - Amorphous alloy coated body and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an amorphous alloy coated body in which an amorphous alloy coated body is formed on the surface of a core material by plastic working, and a method for producing the same.

[Prior Art] An amorphous alloy is generally called an amorphous alloy, and does not have a crystal structure like a metal and has no atomic arrangement periodicity and is in a disordered state. Therefore, even in the X-ray diffraction test, it does not show a clear peak like a metal, and its atomic arrangement is close to that in a liquid state.

Amorphous alloys have high mechanical strength, low coefficient of thermal expansion, low radiation damage, and excellent chemical corrosion resistance and wear resistance. In addition, since an amorphous material as a magnetic material does not have the structure anisotropy such as crystal anisotropy, lattice defects and grain boundaries as seen in an amorphous alloy, the coercive force and the non-permeability are extremely high. It exhibits excellent properties. Therefore, the amorphous alloy has an electromagnetic core,
A wide range of applications such as various sensors and electromagnetic clutches are expected.

As a method for obtaining an amorphous alloy, there are a vacuum vapor deposition method, a sputtering method, a plating method, etc., but these are all limited in the alloy structure that can be obtained, and although suitable for forming a thin film of an amorphous alloy, It is not possible to obtain a large amount of amorphous alloy.
In addition, as a method for obtaining a large amount of large amorphous alloy, there is a liquid quenching method, which is a method of rapidly cooling and supercooling a molten metal or alloy to freeze its structure to make it amorphous. is there.

The use of the amorphous alloy thus obtained has the following problems. First, even amorphous alloys obtained by the liquid quenching method can only obtain fibrous, ribbon-like or flake-like substances with a thickness of 0.01 cm at most, and those with a thickness greater than this can be cooled. Secondly, it is difficult to obtain it due to the relation of speed. Secondly, the crystallization temperature at which these amorphous alloys are crystallized is relatively low, and a large compact is formed from fibers, ribbons, powders, etc. of the amorphous alloy. It may be crystallized immediately by heating or machining to obtain or bond it to another crystalline base material.In this way, in the case of an amorphous alloy, the usual sintering method or welding method is Random atomic arrangement that is characteristic of amorphous,
Since it is crystallized by heat, various proposals have been made for producing a thick alloy from a fibrous, ribbon-shaped or flake-shaped amorphous alloy. These proposals include a laser method (JP-A-59-101287), a method of using a bonding material (JP-A-60-102706), and an impact method (JP-A-59-74).
33), high temperature and high pressure method (JP-A-60-24346) and high temperature extrusion method (HHLiebermann, Materials Scien)
ce and Engineering, 46 (1980) 241-248). Among the above methods, the laser method has a drawback that the number of thin plates is the joining limit and the joining is weak because the joining is partial, and the method of using the matching material has the drawback that the joining portion is weak and the magnetic characteristics are also poor. Further, the impact method is expensive because it uses an expensive explosive, and the high temperature and high pressure method has a problem that the sample size is limited.
On the other hand, the matching of amorphous alloys of industrial materials is also performed by the laser method,
Although it is possible to use the bonding material and the impact method, both have a problem of insufficient strength of the bonding portion.

By the way, there is a torque sensor as a device utilizing the magnetic characteristics of an amorphous alloy. A torque sensor is a sensor that adheres a magnetostrictive material to the surface of the drive shaft and detects the change in the magnetic characteristics of the magnetostrictive material by subjecting it to the stress applied to the drive shaft.This magnetostrictive material uses an amorphous alloy. is there. When using an amorphous alloy for this torque sensor, what is required is to obtain a cylindrical amorphous alloy block and how to firmly fix this cylindrical amorphous alloy block to the drive shaft surface. It is. As mentioned above, amorphous alloys have high strength and high altitude, and they crystallize at a low temperature of 400 to 500 ° C, so common welding methods such as welding and brazing cannot be used like ordinary metal materials. The joining of the drive shaft and the amorphous alloy is the key to the amorphous alloy torque sensor.

As a proposal to obtain a cylindrical amorphous alloy block, JP-A-60
There is an invention of -204804 publication. According to the present invention, when an amorphous powder compact having a hollow portion is manufactured, a preform having a portion substantially corresponding to the hollow portion is made of another kind of powder, and then the preform is compression-solidified by a shock wave molding method. It is formed into a hollow portion by molding and then removing the powder solidified portion of another kind of the solidified molded body obtained. However, the present invention has a problem that the method for applying a shock wave is not simple.

Further, as a proposal for forming a drive shaft as a base material and forming an amorphous metal coating layer directly on the surface of the base material, Japanese Patent Laid-Open No. 60-1940
There is an invention of Japanese Patent No. 85. According to the present invention, a base material and an amorphous metal are placed in a metal container and subjected to high energy processing to form a coating layer of the amorphous metal on the surface of the base material. In this invention, high energy processing means
It is an explosion-molding process, the bond between the base material and the coating layer of amorphous metal is strong, and the magnetic properties of the coating layer are excellent, but since it is an explosion-processing process, there is a great risk and the processing cost is very expensive. There is a drawback that

There is an invention of US Pat. No. 4,377,622 as a method for obtaining an amorphous alloy block by hot extrusion. According to the invention, a metal container is filled with a thin wire amorphous alloy so as to have a theoretical density of about 50 to 60%, and the container is sealed with a stopper to form a billet for extrusion. A columnar amorphous alloy block is obtained by heating to a processing temperature between crystallization temperatures and extruding at this processing temperature at a cross-section reduction rate of at least 3.5 to 1 (about 70%). . Further, in another embodiment of the present invention, a core material is installed in the center of the container, an amorphous alloy is filled between the container and the core material, and after the container is closed, a plastic transition temperature and a crystallization temperature are similarly set. A method of obtaining a cylindrical amorphous alloy block by extruding at a processing temperature of 10 and removing the core material by machining is disclosed.

In this invention, in order to satisfactorily bond the core material and the amorphous alloy coating layer, the cross-section reduction rate in the extrusion process is about 70%.
More than required. This requires extensive equipment to apply a significant extrusion load. In addition, during extrusion processing, a difference in extrusion speed between the core material and the amorphous alloy occurs, slippage occurs at the boundary between the two, and a crack is formed on the amorphous alloy side, resulting in poor bonding between the two. Cause problems.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above problems and provide an amorphous alloy coated body excellent in bonding between a core material and an amorphous alloy and a method for producing the same. To do.

[Means for Solving the Problems] The amorphous alloy coated body of the present invention comprises a core material having irregularities on the surface and an amorphous alloy coated on the surface of the core material. A coating layer of an amorphous alloy was formed on the surface of the core material by plastically working the core material and the amorphous alloy at a forming temperature between the plastic transition temperature and the crystallization temperature of the crystalline alloy. That is the summary.

Further, the gist of the method for producing an amorphous alloy coated body of the present invention is that it comprises the following steps.

a) a step of fixing a core material having irregularities on the surface at the center of a metal container with one end open, and filling an amorphous alloy between the container and the core material, b) the open end of the container A step of inserting a stopper into the container to seal the container to form a forming billet, c) heating the forming billet to a forming temperature between the plastic transition temperature and the crystallization temperature of the amorphous alloy, and performing plastic forming at the forming temperature The process of doing.

[Operation] The amorphous alloy used in the present invention has excellent magnetic characteristics in, for example, Fe-based and Co-based, and may be in the form of powder, fine wire or ribbon. First, a core material having surface irregularities is fixed to the center of a metal container whose one end is open. The unevenness of the surface of the core material may be such that the amorphous alloy does not slip on the surface of the core material when the core material and the amorphous alloy undergo plastic deformation.For example, the surface of the core material is knurled. You can use what you did. Next, the amorphous alloy is filled into the space between the container and the core material. If it is a powder, it is filled while repeatedly performing cold precompression, and if it is a thin wire or a thin strip, it is wrapped around the core material at a high density. The packing density of an amorphous alloy is about the theoretical density.
About 40% is sufficient. After the filling of the amorphous alloy is completed, the container is evacuated to about 10 ⁻³ Torr or more and inert substitution of argon, nitrogen, etc. is performed. This eliminates the air in the container and prevents the oxidation of the amorphous alloy. Next, a plug is inserted into the open end of the container and hermetically sealed to form a molded billet. Welding or high temperature type adhesives such as ceramics type adhesives may be used to seal the plugs.

The forming billet is heated to a forming temperature between the plastic transition temperature and the crystallization temperature. Here, the plastic transition temperature refers to the temperature at which, when stress is applied to an amorphous alloy at various temperatures, it exhibits a non-uniform deformation behavior at a certain temperature or lower, but shows a uniform deformation behavior at a temperature higher than that. Of. Therefore, when the amorphous alloy is plastically deformed at a forming temperature between the plastic transition temperature and the crystallization temperature, the amorphous alloy is deformed uniformly as a whole.

In the present invention, the forming billet undergoes plastic working while being heated to the forming temperature between the plastic transition temperature and the crystallization temperature of the amorphous alloy. Specifically, the plastic working is working such as extrusion or drawing, and the amorphous working receives shearing force by the plastic working. Bonding does not occur in an amorphous alloy by mere compression, but when a shear stress component acts, contact between adjacent amorphous alloys is promoted, and the flow of plastic deformation increases this contact area and the oxides on the surface and Since the film of impurities is destroyed, the joining of amorphous alloys takes place.

The extrusion die used for plastic deformation is preheated to the forming temperature by a heating coil or the like. Further, it is necessary to process the molding temperature at a temperature below the crystallization temperature minus the processing heat generation temperature so that the molding billet does not exceed the crystallization temperature due to the temperature rise due to the processing heat generation. A cross-section reduction rate of about 40% is sufficient for extrusion processing.

In the plastic working of a forming billet, the core material and the amorphous alloy have different densities, so that the core material tends to stretch first during forming. Therefore, if there is little friction between the amorphous alloy and the core material, slippage will occur at the boundary between the amorphous alloy and cracks on the side of the amorphous alloy, and the shear that greatly contributes to the joining of the amorphous alloys will not occur. It does not add enough to the crystalline alloy. But,
In the present invention, since the surface of the core material is provided with irregularities,
The friction between the core material and the amorphous alloy is large, the amorphous alloy and the core material are stretched similarly, slippage does not occur at the boundary, and the coating layer of the amorphous alloy is not cracked. Further, there is no shear loss caused by slippage, and shear can be effectively added to the amorphous alloy. Further, due to the unevenness of the surface of the core material, an amorphous alloy coated body in which the core material and the amorphous alloy are mechanically strongly bonded can be integrally molded.

Example An example of the present invention will be described in detail to clarify the effect of the present invention.

(Example 1) As shown in the sectional view of FIG. 1, outer diameter 29 mm, inner diameter 26 mm, S45C
Prepare a cylindrical container 10 made of 14 mm in the center of this container 10.
A knurled core 14 having a large number of linear grooves with a pitch of 1 mm and a depth of 0.5 mm was fixed to the surface of φ55 mm S55C, intersecting at 45 ° and 90 ° with respect to the shaft center. Note that the fixed end of the core material 14 is not knurled. Further, the tip 16 of the container 10 was processed at an angle of 90 °. Then the container 10 and core 14
Between the amorphous alloy powder (component; Fe ₇₈ B ₁₃ Si ₉ , grain size; 74
~ 105 μm) 18 while repeatedly cold pre-compressing the density of about 4
It was filled to 0%. After filling the amorphous alloy 18, the container 10 was evacuated to 10 ^-3 Torr, and the atmosphere was replaced with argon. Immediately, the plug 20 was inserted and sealed with a ceramic adhesive to make the container.
10 was closed to form a molding billet 22. For comparison, a polished core material 14 in which the knurling 12 was not applied to the surface of the core material 14 was separately prepared and similarly filled with an amorphous alloy 18 to form a molding billet 22.

Next, a graphite lubricant is applied to the forming billet 22 and heated to various forming temperatures as shown in Table 1, which is inserted into the extrusion die 24 shown in FIG. As shown in FIG. 5, an amorphous alloy coating 28 having an amorphous alloy coating layer 26 formed on the surface of the core material 14 was obtained. The extrusion mold 24 was previously heated to the molding temperature by the heating coil 30. The cross-section reduction rate of the extrusion mold 24 was 40%, and the approach angle was 90 °.

The obtained amorphous alloy coated body was cut, and the density of the coating layer, the presence or absence of cracks, the magnetic properties and the amorphous alloy content were inspected and the results are shown in Table 1.

As known from Table 1, those molded at 500 ° C
Although it was crystallized in all cases, it was confirmed that the others were kept in an amorphous state. Below 300 ° C, all the samples had many cracks and were very porous. However, at 350 ° C or higher, a dense coating was obtained, but cracks did not disappear in the surface-polished state, whereas those subjected to surface knurling had no cracks and a dense and good coating layer. 26 was obtained, and its density was 98.5% or more of the theoretical density. A cross-sectional photograph of a sample obtained by molding the surface-polished state at 400 ° C is shown in Fig. 4, and the surface knurled at 400 ° C.
A cross-sectional photograph of the sample molded in step 1 is shown in FIG. 5, and a further enlarged photograph of FIG. 5 is shown in FIG. 4, 5, and 6
As is clear from the figure, many cracks oblique to the extrusion direction are observed in the surface-polished state shown in FIG. 4, whereas no cracks are observed in the knurled ones shown in FIGS. 5 and 6. It can be seen that a dense coating layer is formed without being observed.

When the amorphous alloy 18 is a thin wire or a thin strip, as shown in FIGS. 7 and 8, the thin wire or the thin strip is wound around the core material 12 at a high density before being placed in the container 10. The billet 22 may be formed by inserting it and plugging it 20.

Example 2 The sample of the present invention and the sample of the comparative example, which were molded at 400 ° C. in Example 1, were processed into a torque sensor shaft 32 as shown in the sectional view of FIG. 9, and the torque sensor of FIG. As shown in the schematic diagram, the drive shaft 4 was connected and the torque was detected.

The operation of the torque sensor shown in FIG. 10 will be described. A coil 2 for exciting the coating layer 26 and a coil 3 for detecting the magnetostrictive characteristic of the coating layer 26 are provided near the surface of the drive shaft 4 on which the coating layer 26 is formed. When installed, the electromotive force caused by the distortion due to the torque transmitted to the drive shaft 4 can be measured. This electromotive force is extracted as an amplified electric signal. As a detection circuit, a signal output from the transmitter 6 is converted into a square wave by the drive circuit 7, and a current is added to the exciting coil 2. The electromotive force generated by the distortion generated by driving the detection coil 3 is amplified by the AC amplifier 8, sampled by the sampling circuit 9, and further compared with the excitation square wave to detect the torque. In this embodiment, the excitation frequency is 1,1khz and the gap is 0.
The torque was detected as 5 mm.

FIG. 11 is a diagram showing the relationship between the torque applied to the example of the present invention and the comparative example and its output. In Comparative Example 1, permalloy is bonded around the core material without providing irregularities, and in Comparative Example 2, Ni plating is formed around the core material. As is apparent from FIG. 11, the torque applied to the amorphous coating body that is the drive shaft and the output obtained from the amorphous alloy coating layer as a result of the invention are in good proportion as compared with the comparative example. The relationship is established. Further, the difference in hysteresis due to the rise and fall of the applied torque is smaller and the sensitivity is better in the example of the present invention than in the comparative example.

In addition, in the present invention, the unevenness of the core material is not limited to that obtained by knurling as shown in FIG. 1, but the unevenness may be provided in the circumferential direction if the core material has a cylindrical shape. May be provided. The arrangement of such irregularities can eliminate the difference in extrusion or drawing speed between the core material and the amorphous alloy during extrusion or drawing.
It is possible to prevent cracking of the coating layer made of an amorphous alloy. As for the shape of the unevenness, when the core material is cylindrical, the unevenness in the axial direction and the unevenness in the above arrangement may be used in some cases.

[Effects of the Invention] As described above, the amorphous alloy coated body of the present invention and the method for producing the same are such that the core material having surface irregularities is fixed to the center of the container, and the amorphous material is provided between the container and the core material. The alloy is filled with a high-quality alloy, the container is capped and sealed to form a molded vitreto, and the molded vitreto is plastically worked at a molding temperature between the plastic transition temperature and the crystallization temperature of the amorphous alloy to form a core material surface. In order to obtain a coating layer of an amorphous alloy, the amorphous alloy coating obtained by the present invention has no defects such as cracks in the coating layer and has a sufficiently high density, and also has excellent magnetic properties. Also, it has a number of excellent effects such as extremely strong bonding with the core material. By using the amorphous alloy coated body of the present invention, a magnetic body such as a torque sensor,
It can be used for many parts as a magnetic head, a wear-resistant sliding member, a filter material having corrosion resistance, an electrode material for soda electrolysis and a fuel cell.

[Brief description of drawings]

FIG. 1 is a sectional view of a forming billet, FIG. 2 is a sectional view of an extrusion die, FIG. 3 is a sectional view of an amorphous alloy coated body, FIG.
5 and 6 are micrographs showing the metallographic structure of the cross section of the coating layer, FIG. 7 is a cross section of a molded billet filled with a ribbon-shaped amorphous alloy, and FIG. 8 is a thin-line amorphous. 9 is a sectional view of a molded billet filled with an alloy, FIG. 9 is a sectional view of a torque sensor shaft, FIG. 10 is a schematic diagram of a torque sensor, and FIG. 11 is a diagram showing a relationship between torque and torque sensor output. 10 …… container, 12 …… knurling, 14 …… core material, 18…
… Amorphous alloy, 20 …… Stopper, 22 …… Molded billet, 26 ……
Amorphous alloy coating layer, 28 ... Amorphous alloy coating

Front page continuation (72) Inventor Shoji Akai 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd. (56) Reference JP-A-53-57170 (JP, A) JP-A-61-69953 ( JP, A)

Claims (13)

[Claims] 1. A molding temperature comprising a core material having irregularities on its surface and an amorphous alloy coated on the surface of the core material, the molding temperature being between the plastic transition temperature and the crystallization temperature of the amorphous alloy. 2. An amorphous alloy coated body, wherein a coating layer of an amorphous alloy is formed on the surface of the core material by plastically working the core material and the amorphous alloy. 2. The amorphous alloy coated body according to claim 1, wherein the irregularities on the surface of the core material are irregularities generated by knurling the surface of the core material. 3. The amorphous alloy coated body according to claim 1 or 2, wherein the plastic working is extrusion working. 4. The amorphous alloy coated body according to claim 1 or 2, wherein the plastic working is drawing. 5. The amorphous alloy coated body according to claim 1, wherein the density of the coating layer of the amorphous alloy is 98% or more of the theoretical density. 6. A method for producing an amorphous alloy coated body, which comprises the steps of: a) fixing a core material having an uneven surface on the center of a metal container whose one end is open. Filling the amorphous alloy between the container and the core material, b) inserting a plug into the open end of the container to seal the container into a molded billet, c) the amorphous billet Heating to a forming temperature between the plastic transition temperature and the crystallization temperature of the fine alloy, and plastically working at the forming temperature. 7. The method for producing an amorphous alloy-coated body according to claim 6, wherein the container is filled with an amorphous alloy, and then the container is evacuated and then replaced with an inert gas. 8. The method for producing an amorphous alloy coated body according to claim 6, wherein the evacuation is performed at least 10 ⁻³ Torr. 9. The filling rate of the amorphous alloy is at least 40%.
The method for producing an amorphous alloy coated body according to claim 6, wherein 10. The method for producing an amorphous alloy coated body according to claim 6, wherein the plastic working is extrusion molding. 11. The method for producing an amorphous alloy coated body according to claim 6, wherein the plastic working is drawing. 12. A cross-section reduction rate due to the plastic working is at least 40%.
11. The method for producing an amorphous alloy coated body according to any one of 10 items. 13. The method for producing an amorphous alloy coated body according to claim 6, wherein the container is removed by machining after the plastic working.