JPH07103492B2 - Copper alloy filament and its manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a copper alloy filament and a method for producing the same, and more particularly to a fibrous magnetic material, a resistance change type temperature sensor material and the like having good toughness and handleability. And a method for producing the same, which is useful as a copper alloy filament.

[Prior Art] For example, a Cu-Mn-Al-based copper alloy has magnetism and can be applied to various applications as a magnetic material, and is expected to be effectively used as a material for a resistance change temperature sensor. Has been done.

By the way, in order to put the above copper alloy into practical use as a sensor material, etc., it is necessary to make the shape as small as possible and further increase the electrical resistance. For that purpose, thinning is an effective means. Considered to be one.
However, the above-mentioned copper alloy is hard and brittle and has poor workability, and it is very difficult to make it fine by machining.

On the other hand, as one of the methods for thinning fragile metal materials,
The rotating submerged spinning method described in Japanese Patent Application Laid-Open No. 55-64948 previously disclosed by the applicant of the present application has been known, and this method is expected to be an extremely useful method.

That is, according to this method, a cooling liquid is injected into the inner peripheral surface of a rotating cylindrical hollow drum, and this is pressed against the inner peripheral surface by a centrifugal force to form a cooling liquid layer. This is a method in which a molten metal jet is sprayed in the form of thin wires to be rapidly cooled and solidified, and even brittle metallic materials can be easily made into thin wires.

[Problems to be Solved by the Invention] By using the above-mentioned spinning submerged spinning method, even a copper alloy as described above can be easily formed into a thin wire, and a resistance change type temperature sensor or the like is put into practical use. It is expected that it will open the way to. Then, when the above-mentioned spinning submerged spinning method was applied to the copper alloy, it was confirmed that even a brittle copper alloy could be easily thinned. However, among the copper alloy filaments obtained in this way, especially thicker (150 μm
It was found that the (super) is very brittle and difficult to handle because it is easily broken when it is bent more than 90 degrees, and its versatility is poor. If the thickness is 150 μm or less, it may be bent or may be cut at the time of bending depending on the bent portion. Further 80μ
Almost certainly when using a filament with a diameter of m or less
It was possible to bend 180 degrees. Therefore, looking at the internal structure of this copper alloy filament, at the location where the above-mentioned bending cutting occurs, two or more crystals are always (in any cross section) in the transverse section orthogonal to the filament axis. It was confirmed that the grains were present and had a so-called polycrystalline structure. On the other hand, it is 18 in the single crystalline part of bamboo knots (solid columnar structure, not hollow).
Bending is possible at 0 degrees, and as the copper alloy filament becomes thinner, the proportion of the single crystalline portion as described above increases,
It has been found that when the metal filament has a size of 80 μm or less, interstitial single crystalline portions of bamboo nodes are connected through grain boundaries corresponding to bamboo nodes over almost the entire length. Therefore, the inventors of the present invention proceeded with research to improve the physical properties of the copper alloy filament composed only of the above-mentioned polycrystalline portion, and independently of the thickness of the copper alloy filament, at least a part of the filament had a bamboo knot-shaped single-piece structure. If a crystalline part can be made, that part will exhibit excellent toughness, and
I thought that bending would be possible. That is 150 μmφ
Even in the case of the above copper alloy filament, if a single crystallized portion as described above can be formed even in part, the toughness is improved in mechanical properties, and the electrical,
It was hoped that the magnetic properties could be modified into interesting ones.

The present invention is intended to realize such an expectation, and specifically has a single crystalline structure in at least a part of the longitudinal direction, has good toughness and handleability, and is electrically and magnetically Another object of the present invention is to provide a copper alloy filament having excellent properties and a method for producing the same.

[Means for Solving Problems] The structure of the copper alloy filament according to the present invention has a crystal grain in which a single crystal having no dendrite-like structure is formed in a bamboo node shape in at least a part of the filament longitudinal direction. The gist of the present invention is that it has a structure in which it is continuously connected with a boundary as a boundary, and the structure of the method for producing a copper alloy filament according to the present invention is configured by centrifugal force in a rotating cylindrical drum. A molten copper alloy is injected into the formed cooling liquid through a spinning nozzle, and a copper alloy filament obtained by cooling and solidifying is heat-treated at a temperature lower than the melting point of the copper alloy and at least 2/3 of the melting point. However, it has a gist.

[Operation] As a technique for making an alloy into a single crystal, a solidification method and a strain annealing method are well known. That is, the solidification method is a method of producing a single crystal by utilizing solidification from molten metal, while the strain annealing method heats (anneals) the processed metal.
It is also called a recrystallization method because it utilizes a recrystallization technique for generating new crystal grains. The latter strain annealing method is carried out by applying an appropriate strain to a metal material formed into a linear or plate shape, and then heating this to a high temperature.

The present inventors, taking advantage of the above knowledge, think that it is possible to modify the polycrystalline and fragile copper alloy filament to be a single crystalline one with excellent flexibility and a single crystalline, strain as described above. Various experiments were conducted including the annealing method.

As a result, the polycrystalline copper alloy filament obtained by the rotating submerged spinning method is directly less than the melting point of the copper alloy and has a melting point of less than the melting point of the copper alloy without a process of giving strain by treatment such as pre-annealing or drawing. When heat-treated at a temperature of 2/3 or higher, the polycrystalline structure formed in the spinning process is modified to have grain boundaries that cross the filament axis and have non-uniform spacing, and do not have a dendrite-like structure. It was clarified that the single crystal part had a characteristic structure that was continued. It was confirmed that the copper alloy filaments having such a structure have very good toughness and are extremely flexible without breaking even when they are closely bent to 180 degrees. In this specification, "bamboo knot"
The term refers to a state in which the crystal grain boundaries formed in the cross-sectional direction of the filament have an appearance as if they were bamboo knots when observed under a microscope, although they differ slightly depending on spinning conditions and heat treatment conditions. About the length of the filament
They are formed at irregular intervals of 0.3 to 20 mm (usually about twice the filament diameter or more), and the knots of the bamboo are composed of a single crystal having no dendrite-like structure. FIG. 3 is a typical example of the copper alloy filament according to the present invention, and schematically shows a structure in which a single crystal is continuously formed in a node shape of bamboo. Hereinafter, such a structure is referred to as a bamboo structure.

Although it is possible to make the bamboo-like structure by reducing the diameter of the copper alloy filament, as shown in FIG. 4 (a), in the copper alloy filament before heat treatment, each single crystal part has a dendrite shape. Have an organization. FIG. 4 (b) shows
It is a drawing-substitute micrograph (copy) of a copper alloy filament having a dendrite-like structure, which was taken after an etching treatment for the purpose of clearly revealing the dendrite-like structure. The copper alloy filament having such a dendrite structure has insufficient toughness. In order for the copper alloy filament to have high toughness and exhibit excellent flexibility, it is necessary that each single crystal part does not have a dendrite structure, as shown in Fig. 5 (a). Is. FIG. 5 (b) is a drawing substitute micrograph (copy) of the copper alloy filament according to the present invention, which has been subjected to the etching treatment.
Is. It can be seen that it does not have a dendrite structure. In the following description, a bamboo structure having no dendrite structure is referred to as a bamboo structure according to the present invention.

As described above, the copper alloy filament of the present invention is characterized in that it has the bamboo structure according to the present invention. However, it does not mean that the entire filament has to be composed of the bamboo structure according to the present invention. However, if at least a part of the filament has a bamboo-like structure according to the present invention,
The flexibility is remarkably improved as compared with the conventional polycrystalline copper alloy filament.

The point that the bamboo-like structure according to the present invention can be obtained by heat-treating the copper alloy filament obtained by the rotating submerged spinning method without any pretreatment has not been theoretically elucidated, but the heat treatment It is presumed that the bamboo structure according to the present invention was generated by the disappearance of the dendrite structure and probably by the strain introduced into the filament during spinning having a significant influence on the generation of the bamboo structure. In any case, the copper alloy filament having a bamboo-like structure according to the present invention becomes extremely rich in flexibility, capable of closely bending at 180 degrees, and has a significantly large elongation in a tensile test. The copper alloy filament having a bamboo-like structure according to the present invention is a material that is easy to see and handle, and can be processed at higher levels, and can be drawn and rolled. Further, a part of the copper alloy filament having a bamboo structure can be cut out and used as a single crystal. In this case, since the copper alloy filaments having the same diameter are cut out, a single crystal having a uniform diameter can be obtained, and further, a single crystal having different orientations in the axial direction can be obtained. Although various things can be considered as the copper alloy used in the present invention,
Of these, the most preferable is a copper alloy containing Mn: 1 to 35 atomic%, Al: 5 to 35 atomic% (the sum of Mn and Al is 6 to 60 atomic%), and the balance Cu and unavoidable impurities. However, when a copper alloy having a composition deviating from the above-mentioned preferable component composition is used, the bamboo in accordance with the present invention can be used even when the spinning submerged spinning method is adopted as described in detail later and the heat treatment is then performed in a predetermined temperature range. It is difficult to obtain a structure having a ring-shaped structure, and thus it is difficult to sufficiently improve flexibility.

Next, a method for manufacturing the copper alloy filament according to the present invention will be described. The basic construction of the spinning method adopted in the present invention is in accordance with the spinning submerged spinning method disclosed in JP-A-55-64948. For example, FIGS. 1 and 2 are a schematic front view and a partially cutaway side view illustrating the method, and by rotating the rotating drum 6 at a high speed, the rotating liquid film layer 8 is formed on the inner peripheral surface side.
To form. Then, the molten copper alloy is jetted from the jet nozzle 2 on the lower surface of the crucible 1 toward the liquid surface 9 of the liquid film layer 8 to jet the molten copper alloy into filaments 4 and rapidly solidifies them on the inner peripheral wall of the rotary drum 6. Winding around. In the figure, 3 is a heater for melting metal, 5 is an inert gas for jetting molten copper alloy, 7 is a motor, and 10 is a belt. When the peripheral velocity of the rotating liquid film layer is set to be substantially the same as or slightly higher than the jetting speed of the molten copper alloy from the jetting nozzle 2, a copper alloy filament having good cross-sectional uniformity can be easily obtained. The cooling liquid used here may be a pure liquid, a solution, an emulsion, or the like,
Water is most preferable in terms of cost and cooling efficiency. The rotating drum may be horizontal or vertical, but the surface speed of the liquid film layer in the drum is about 400 to 900 m / min, the angle of entry of the molten copper alloy into the liquid film layer is 50 to 80 °, the jet nozzle 2 and cooling The distance from the liquid surface 9 is preferably about 0.5 to 10 mm.
By the way, the copper alloy filament obtained by the spinning liquid spinning method as described above is a polycrystalline structure having two or more crystal grains in its cross section and having many crystal grains in the axial direction of the filament. Although very brittle, when this copper alloy filament is heat-treated at a temperature lower than the melting point of the copper alloy and not less than 2/3 of the melting point for about 0.2 to 5 hours,
The bamboo-like structure according to the present invention is modified into a highly flexible material. However, when the temperature is out of the above range, such a reforming effect cannot be obtained. The heat treatment is preferably performed in an inert gas atmosphere or vacuum.

[Examples] Example 1 A rotary submerged spinning method as shown in Figs.
A copper alloy filament having a diameter of 180 μm was produced using a molten copper alloy having a composition of (50) -Mn (25) -Al (25) atom% (melting point: about 920 ° C.). Water at 10 ° C. was used as the cooling liquid. Then, this copper alloy filament was heat-treated at 800 ° C. for 3 hours or 5 hours under a reduced pressure of about 0.5 torr or less.

The copper alloy filament before heat treatment has a polycrystalline structure having three crystal grains in the cross section and a large number of crystal grains arranged in the axial direction of the filament, and is a fragile material that easily breaks when bent. However, the two types of filaments subjected to the heat treatment had crystal grain boundaries in the direction transverse to the filaments at intervals of about 0.3 to 20 mm in the longitudinal direction, and had a dendrite-like structure between the crystal grain boundaries. It had a bamboo-like structure consisting of a non-single crystalline material, and was a flexible material that did not break even when closely bent at 180 degrees.

Example 2 Cu (60) -Mn (20) -Al (20) atom%, Cu (55) -Mn
(20) -Al (25) and Cu (45) -Mn (30) -Al (25) three kinds of copper alloy melts with a composition of atomic% (melting points are about 93 each
0 ° C., about 920 ° C. and about 950 ° C.) were used to prepare a copper alloy filament having a diameter of 180 μm in the same manner as in Example 1, and then heat-treated at 900 ° C. for 3 hours under a reduced pressure atmosphere of about 0.5 torr or less. Each of the obtained heat-treated products had a bamboo-like structure according to the present invention over almost the entire length, and each was highly flexible and capable of 180-degree contact bending.

Example 3 Cu (65) -Mn (2) -Al (33) atom%, Cu (58) -Mn
(34) -Al (8) atom% and Cu (92) -Mn (3) -Al
(5) Copper alloy with each composition of atomic% (melting point is about 10 each
Spinning and heat treatment were carried out in the same manner as in Example 2 except that 30 ° C, about 890 ° C, about 1060 ° C) were used.

Each of the obtained filaments had a bamboo-like structure in which single crystals having no dendrite-like structure were connected over almost the entire length, and the filaments had excellent flexibility capable of being intimately bent by 180 degrees.

Example 4 A copper alloy having a composition of Cu (50) -Mn (25) -Al (25) atomic% (melting point: about 920 ° C.) was used to prepare a filament having a diameter of 180 μm in the same manner as in Example 1. , Then about 0.5to
3 at 620 ° C and 300 ° C under reduced pressure of rr
Heat treatment was performed for 5 hours or 5 hours. All of the filaments heat-treated at 620 ° C had a bamboo-like structure and were flexible so that they could be bent in close contact with each other at 180 degrees, but none of the filaments heat-treated at 300 ° C had a bamboo-like structure. It was fragile because it was polycrystalline having two or more crystal grains in every cross section.

[Advantages of the Invention] The present invention is configured as described above, and while maintaining the original excellent magnetic and electrical characteristics of a filament made of a copper alloy, it modifies the weakness, which is the greatest drawback of the filament. It is possible to impart extremely flexible and bendable characteristics, and it is possible to remarkably improve the handling property. As a result, it can be easily applied to, for example, a resistance change type temperature sensor and the like, and it can be expected that the field of application will be greatly expanded.

[Brief description of drawings]

FIGS. 1 and 2 are views for explaining the spinning method in a rotating liquid, FIG. 1 is a schematic front view, and FIG. 2 is a partial cross-sectional side view. FIG. 3 is an explanatory view showing a bamboo structure of a copper alloy filament. FIG. 4 (a) is an explanatory view schematically showing a longitudinal section of a copper alloy filament having a dendrite structure, and FIG. 4 (b) is a drawing-substitute micrograph (copy) showing the dendrite structure. . FIG. 5 (a) is an explanatory view schematically showing a longitudinal section of a copper alloy filament not having a dendrite-like structure, and FIG. 5 (b) is a drawing-substitute microscope for a copper alloy filament not having a dendrite-like structure. It is a photograph (copy). 1: crucible 2: jet nozzle 3: heater, 4: filament 5: inert gas, 6: rotating drum 7: motor, 8: cooling liquid 9: cooling liquid level, 10: belt

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI technical display location // D01D 5/08 F (72) Inventor Hideaki Ishihara 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd.

Claims (5)

[Claims] 1. A structure in which a single crystal having no dendrite-like structure is continuously formed at least at a part in the longitudinal direction of a filament with a grain boundary formed like a nodule of bamboo as a boundary. A copper alloy filament characterized in that. 2. A Cu-Mu-Al-based alloy containing Mn: 1 to 35 atomic%, A
The copper alloy filament according to claim 1, wherein l: 5 to 35 atomic% (however, the sum of Mn and Al is 6 to 60 atomic%), and the balance is Cu and inevitable impurities. 3. A molten copper alloy is formed into a filament by a melt-spinning method, and is less than the melting point of the copper alloy and 2/3 of the melting point.
Claim 1 which is heat-treated at the above temperature
Alternatively, the copper alloy filament according to item 2. 4. A copper alloy filament having a structure in which a single crystal having no dendrite-like structure is continuously connected at a grain boundary formed in a node shape of bamboo as a boundary in at least a part of the filament longitudinal direction. In manufacturing, a molten copper alloy is jetted through a spinning nozzle into a cooling liquid formed by centrifugal force in a rotating cylindrical drum, and a copper alloy filament obtained by cooling and solidifying the molten copper alloy has a melting point of the copper alloy. A method for producing a copper alloy filament, characterized in that the heat treatment is performed at a temperature of less than 2/3 of the melting point. 5. A copper alloy comprising Mn: 1 to 35 atomic%, Al: 5 to 35 atomic% (however, the sum of Mn and Al is 6 to 60 atomic%), and the balance Cu.
And the production method according to claim 4, which is an unavoidable impurity.