WO2007046378A1

WO2007046378A1 - Cu-Ag ALLOY WIRE HAVING HIGH STRENGTH AND HIGH CONDUCTIVITY AND METHOD FOR MANUFACTURE THEREOF

Info

Publication number: WO2007046378A1
Application number: PCT/JP2006/320659
Authority: WO
Inventors: Yoshikazu Sakai; Yoko Hori
Original assignee: National Institute For Materials Science
Priority date: 2005-10-17
Filing date: 2006-10-17
Publication date: 2007-04-26
Also published as: JP5051647B2; JPWO2007046378A1

Abstract

Disclosed is a Cu-Ag alloy wire having a low Ag content. The wire can be manufactured by performing a cold wire drawing processing prior to and after a thermal treatment for recrystallization in a vacuum or inert gas atmosphere, wherein the processing degree in the latter cold wire drawing processing is 12 times greater than that in the former cold wire drawing processing. The wire has high strength and high conductivity.

Description

High strength and high conductivity Cu-Ag alloy wire and its manufacturing method

Technical field

[0001] The present invention relates to a Cu—Ag alloy fine wire having both high strength and high electrical conductivity and a method for producing the same. More specifically, in detail, an electric wire for an electronic device, a cable for driving a robot, a small motor, and the like. It is useful as a conductor material for coils, small magnet coils, etc., and as a lead wire, conductive panel material, reinforcing material for superconducting wires, etc., having high strength, high strength, and conductivity characteristics. This relates to a thin wire of Cu—Ag alloy and a manufacturing method thereof.

Background art

Conventionally, the strength and conductivity of copper alloys for conductive materials are in a trade-off relationship, and it is known that the strength decreases when the strength is high, and conversely the strength is low when the conductivity is high. ing. For example, in the case of pure Cu, a highly conductive material, the conductivity is almost 100% IACS, but the tensile strength is only 200-400 MPa. On the other hand, in the case of Cu-Be alloy, which is a high-strength material, the tensile conductivity is 900-1500 MPa, and the force conductivity is only up to 50% IACS. Therefore, a fiber reinforced Cu Ag alloy has been developed by the present applicant as a material that overcomes the constraints on the balance between strength and conductivity (Patent Documents 12 and 2). In this copper alloy, 4 32at% (6.6 wt% -44. 4wt%) of Ag was added to Cu to crystallize the primary crystal Cu and the eutectic phase of Cu and Ag uniformly and finely. Thereafter, the wire is cold drawn or rolled to extend the primary and eutectic phases into a filament shape to improve the strength. Furthermore, during the processing, it is dissolved in the primary and eutectic phases by performing multi-stage heat treatment in a vacuum atmosphere or in an inert gas at a temperature of 300-550 ° C and a heat treatment time of 0.5-40 hours. Ag and Cu are deposited to achieve high conductivity as well as high strength. However, in this case, the addition of 4at% ((6.6 wt%) or less of Ag is said to have no effect on strength improvement. In this respect, the addition of a smaller amount of Ag improves the characteristics. In addition, the necessity of adding a large amount of Ag of 6.6 wt% or more is a problem in workability and cost performance. [0003] In order to solve this problem, 1-: cold-working a copper alloy containing L0wt% Ag, and in the middle of this cold-working in a vacuum atmosphere or inert gas at a temperature of 700-950 ° C 0.5-5 hours heat treatment, followed by cold working, and at such a low temperature that no recrystallization occurs in the vacuum atmosphere or inert gas during the cold working, ie 250 ° C or more 400 A manufacturing method has been proposed in which high strength and high electrical conductivity can be realized by performing cold working for 0.5 to 40 hours at a temperature of less than ° C (Patent Document 3). ), Improvement of both strength and electrical conductivity is almost achieved.

Patent Document 1: Japanese Patent No. 2104108

Patent Document 2: Japanese Patent No. 2714555

Patent Document 3: JP-A-6-287729

Disclosure of the invention

Problems to be solved by the invention

[0004] From the background as described above, the present invention solves the conventional problems, and even with a low concentration of Ag additive, it has a high strength (high tensile strength) that can not be realized conventionally by simple means. With high conductivity characteristics, particularly high strength of 600MPa or higher, and 900MPa or higher, it is possible to manufacture ultra-fine copper alloy wires with high conductivity characteristics of 70% 1 ACS or higher. It is an object to provide an Ag alloy fine wire and a manufacturing method thereof.

Means for solving the problem

[0005] The present invention is characterized by the following as a solution to the above problems.

[0006] First: In Cu-Ag alloy thin wire obtained by performing cold wire drawing before and after performing recrystallization heat treatment in a vacuum or an inert gas atmosphere, Machining strength force Cu-Ag alloy thin wire characterized by being 12 times or more in the subsequent process compared to the previous process.

[0007] Second: In the first Cu-Ag alloy thin wire, the Ag content is 1 to 10 wt%.

[0008] Third: A Cu-Ag alloy fine wire, wherein the Ag content in the first Cu-Ag alloy fine wire is 2 to 6 wt%.

[0009] Fourth: In the first Cu-Ag alloy fine wire, the Ag content is 2 to 3 wt%, A Cu—Ag alloy fine wire characterized in that the degree of workability is 18 times or more.

[0010] Fifth: When performing cold wire drawing before and after performing recrystallization heat treatment in a vacuum or an inert gas atmosphere, the degree of work in the subsequent process was increased to 12 times or more of the degree of work in the previous process. A method for producing a Cu—Ag alloy fine wire.

[0011] Sixth: In the fifth method for producing a Cu—Ag alloy fine wire, the method for producing a Cu—Ag alloy fine wire, characterized in that the Ag content power is about 10 wt%.

[0012] Seventh: A method for producing a Cu—Ag alloy fine wire, characterized in that, in the fifth method for producing a Cu—Ag alloy fine wire, the Ag content is 2 to 6 wt%.

[0013] Eighth: In the fifth method for producing a Cu—Ag alloy fine wire, the Ag content is 2 to 3 wt%, and the magnification of the processing degree is 18 times or more. A method for producing a Cu-Ag alloy fine wire.

[0014] The production method of the present invention as described above is uncommon when obtaining a material intended for strength to be held for a relatively long time at a temperature at which sufficient recrystallization occurs during cold working. One of the features is that the strength increases rapidly with the increase in the degree of work and the degree of work 7 ? (However, η = ΙηΑ / Α: Α: Cross-sectional area before processing, Α: Cross-sectional area after processing) is 12 or more

0 0

This is based on the knowledge and confirmation that could not be expected in the past that the upper ultra-high machining area could be processed without intermediate annealing.

[0015] In this way, the amount of Ag added can be greatly reduced, and furthermore, the heat treatment can be carried out to a super-strength region with a degree of processing of 7? = 12 or more at one time during the entire material manufacturing process. Its manufacturing cost can be reduced. The realization of high strength, high conductivity, and ultrafine wire, which was not possible with conventional materials, encouraged the development of new products using this material. In addition, many products that use conductive materials were made compact and lightweight. It is possible to increase the added value of the product. Brief Description of Drawings

[0016] FIG. 1 is a diagram showing a comparison between the conventional method and the method of the present invention as the relationship between the strength of a Cu-3 wt% Ag alloy fine wire and the degree of processing.

FIG. 2 is a diagram showing a comparison between the conventional method and the method of the present invention as the relationship between the strength of the Cu-5 wt% Ag alloy fine wire and the workability. FIG. 3 is a diagram showing a comparison between the conventional method and the method of the present invention as the relationship between the strength and conductivity of a Cu-3 wt% Ag alloy fine wire.

FIG. 4 is a graph showing a comparison between the conventional method and the method of the present invention as the relationship between the strength and conductivity of a Cu-5 wt% Ag alloy fine wire.

[Fig. 5] A graph showing the relationship between the strength and workability of Cu-3wt% Ag fine wire under various heat treatment conditions.

[Fig. 6] A graph showing the relationship between the strength and workability of Cu-5wt% Ag alloy wire under various heat treatment conditions.

FIG. 7 is a graph showing the relationship between the strength of a Cu—Ag alloy fine wire containing lwt% —10 wt% Ag and the degree of calorie in the method of the present invention.

FIG. 8 is a graph showing the relationship between the strength and electrical conductivity of Cu-Ag alloy fine wires containing lwt% -10wt% Ag in the present invention.

FIG. 9 is a graph showing the relationship between Vickers hardness and heat treatment time (Aging Time) when heat-treated at 450 ° C. for a Cu—Ag alloy containing 2 wt% -10 wt% Ag in the present invention.

FIG. 10 is a photograph showing the structure of a Cu-3wt% Ag alloy before and after heat treatment.

[Fig. Ll] A photograph showing the structure of a Cu-5wt% Ag alloy before and after heat treatment.

BEST MODE FOR CARRYING OUT THE INVENTION

[0017] The present invention has the characteristics as described above. Embodiments will be described below.

[0018] First, in terms of the composition of the Cu-Ag alloy fine wire, according to the present invention, the amount of added Ag is in the range of lwt%-1 Owt%, more preferably 2wt%-6wt%. . If it is less than lwt% Ag, high strength cannot be obtained. If it exceeds 10 wt%, the cost performance against the rate of increase in strength with respect to the added amount of Ag is poor. Melting for alloy ingots can be done by various means, such as high-frequency vacuum melting furnaces and melting under atmospheric pressure while flowing an inert gas such as argon or nitrogen gas. . The heat treatment during the cold heating in the production method of the present invention is performed at a temperature that enables recrystallization. Not limited in particular Force that varies depending on Ag composition and degree of covering Generally, for example, 400 ° C or more Temperature conditions below 550 ° C are preferably considered. Below 400 ° C, recrystallization does not proceed sufficiently and Ag precipitation is difficult to occur, and the subsequent increase in strength due to cold working is low. Above 550 ° C, the amount of Ag deposited decreases, and both strength and conductivity tend to decrease.

[0019] The time for this heat treatment is generally considered to be about 0.5 to 50 hours. From the balance of power treatment efficiency, strength, and electrical conductivity, it is preferable that the time is 6 hours or more.

The heat treatment is performed in a vacuum or in an inert gas atmosphere in order to prevent oxidation on the material surface. Since copper and silver are relatively difficult to oxidize, the degree of vacuum may be about lPa, which can be pulled only by a rotary pump. As the inert gas, for example, argon (Ar) or a mixed gas such as hydrogen gas 50% + nitrogen gas 50%, a flow rate of about lOccZmin is sufficient.

[0020] In the manufacturing method of the present invention, such heat treatment is performed during the cold working. This heat treatment only needs to be performed once.

In cold working for wire drawing, various methods such as draw bench, swager, groove roll and the like are adopted, and in thin wire processing, a continuous wire drawing machine is preferably used. Regarding the degree of processing (r?) By cold working, the degree of working is set to 12 or more in the present invention.

[0022] The term "thin wire" in the present invention means a linear or rod-like material. There are no particular restrictions on the straight section. This depends on the application. The diameter is usually considered to be lmm or less.

[0023] In the present invention, a thin wire having high strength and high conductivity expressed by the following mathematical relationship is provided.

That is, the Cu—Ag alloy fine wire of the present invention has a relationship between strength: Y (MPa) and conductivity: X (% IA CS), which is in a range represented by the following formula (1), and is more preferable. Is in the range expressed by the following equation (2).

[0025] [Equation 1]

(1) -40X + 3600≤Y≤ -40Χ + 4525

(2) -40Χ + 4050≤Υ≤ -40Χ + 4525

Conventionally, Cu-Ag alloy thin wires containing lwt% -10wt% Ag having the relationship of strength and conductivity expressed as described above are known! /, N! / ,. [0026] An example will be shown below and will be described in more detail. Of course, the present invention is not limited to the following examples.

Example

[0027] In the following example, a graphite crucible strip (10 X 10 X 30) electrolytic copper was melted (1080 ° C) using a Tamman furnace, and granular silver was added to 1250 ° C. After the temperature is increased, the alloy is melted by pouring into a graphite mold to make a lump.

[0028] In the cold working for wire drawing, the surface of the lump is ground by 1 to 2 mm, followed by a swaging process, and then a die drawing force test on a draw bench.

[0029] Fig. 1 shows the relationship between the strength of a Cu-3wt% Ag alloy processed by the conventional manufacturing method (Patent Document 3) and the manufacturing method of the present invention and a processing degree of 7 ?. In the conventional method, the molten lump is first cold-worked to a working degree of 7? = 0.63 (50%), and then heat-treated at 800 ° C for 3 hours (heat treatment 1: in the atmosphere, in a pine furnace Solution treatment). Along with this, the strength decreases from 450 MPa to 250 MPa. After the heat treatment, cold work is performed up to 7? = 1. 19 (70%), and no recrystallization occurs! /, Heat treatment is performed at a low temperature of 350 ° C for 3 hours (heat treatment 2: vacuum heat treatment furnace (1 Pa ), Precipitation treatment). The strength after heat treatment is 441 MPa, which is slightly higher than that before heat treatment (428 MPa). After the second heat treatment, the strength increases to about 640 MPa by cold working to 7? = 3. 88 (97. 9%), but the strength does not change even if the degree of work increases after that. descend.

[0030] On the other hand, in the method of the present invention, the molten soot lump is cold worked to a working degree of 7? Recrystallization heat treatment is performed in a vacuum heat treatment furnace (lPa) for 15 hours at a temperature of 450 ° C. The strength after this heat treatment decreases from 450 MPa to 250 MPa. The strength is a force that increases slowly by cold working after recrystallization heat treatment. The degree of working is 7? = 4. 45 (98.8%), which is lower than the conventional method. If the degree of workability is 7? = 4.45 (98.8%) or more, the conventional method cannot expect an increase in strength, but the method of the present invention shows that the strength increases significantly as the degree of workability increases.

[0031] Fig. 2 shows the relationship between the strength of a Cu-5wt% Ag alloy processed by the conventional method (Patent Document 3) and the method of the present invention and the degree of processing of 7 ?. It can be seen that the Cu-5wt% Ag alloy shows the same behavior as the Cu-3wt% Ag alloy. [0032] Fig. 3 shows the relationship between the strength and conductivity of a Cu-3wt% Ag alloy processed by the conventional manufacturing method (Patent Document 3) and the manufacturing method of the present invention. When compared at the same strength level, it can be seen that the conductivity of the Cu-3wt% Ag alloy produced by the method of the present invention is more than 5% IACS higher than that of the conventional method.

[0033] Fig. 4 shows the relationship between the strength and conductivity of the Cu-5wt% Ag alloy processed by the conventional method (Patent Document 3) and the method of the present invention. Similarly, in the case of the Cu-5 wt% Ag alloy, it can be seen that the conductivity of the method of the present invention is 5% IACS higher than the conventional method.

[0034] Fig. 5 shows an example of the relationship between strength and workability when Cu-3wt% Ag alloy is heat-treated at various temperatures and times. High-temperature, long-time heat treatment material (450 ° C, 15h material, 450 ° C, 20h) has low strength, short-time heat treatment material (350 ° C, 10h material, 430 ° C, 3h material, 450 ° C, Compared with 5h material), it is lower in the low workability range, but is significantly higher in the high workability range, and the powerful properties that could not be realized in the past are possible with the low-concentration Ag additive. The important thing in this heat treatment is to precipitate the Ag dissolved in the Cu matrix to the maximum extent. For this purpose, it is necessary to hold it for a relatively long time above the temperature at which recrystallization occurs during cold working. When obtaining a material intended for strength, it is important to perform heat treatment that is not common sense. Therefore, the strength after heat treatment is reduced to the strength before cold working, and Cu and Ag are stretched into fibers by the subsequent cold treatment, and high strength is obtained. Figure 6 shows an example of the relationship between the strength and the degree of aging when Cu-5wt% Ag alloy is heat-treated at various temperatures and times. As the Ag concentration increases, the precipitation temperature decreases, so the Cu-5wt% Ag alloy has a lower temperature than the Cu-3wt% Ag alloy, or a relatively short time (410 ° C, 10h, 450 ° C, 5h Good results are obtained by heat treatment of the material. FIG. 7 shows the relationship between the strength and the workability of a Cu-lwt% Ag-10 wt% Ag alloy calored by the production method of the present invention. The Cu—lwt% Ag, 2wt% Ag, and 3wt% Ag alloys were heat-treated at 450 ° C. for 20 hours at a workability = 0.6, respectively. The Cu-4wt% Ag alloy was heat-treated at 450 ° C for 10h at a workability of 7? Cu-5wt% Ag and 6wt% Ag alloys were heat-treated at 410 ° C for 10h at a workability of 7? = 0.6. The Cu-10wt% Ag alloy was heat-treated at 450 ° C for 5h at a workability of 7? After the heat treatment, each alloy was cold worked to a working degree r? = 8. Cu-2wt% Ag and 3wt% Ag alloys were subsequently cold worked to a working degree r? = 11. It can be seen that the strength of each alloy increases with increasing workability, and the rate of increase in strength increases with increasing Ag concentration.

[0035] Fig. 8 shows the relationship between the strength and conductivity of a Cu-wtwt-10wt% Ag alloy (heat treatment conditions are the same as in Fig. 7). In addition to a single heat treatment during the cold working process, it can be drawn to a high-strength work area with a workability r? = 11 or more without annealing. The strength and conductivity of Cu-2wt% Ag alloy is 1200MPa, 81.7% IACS, Cu—3wt% Ag alloy is 1400MPa, 76.4% IACS, which provides high strength and high conductivity that cannot be achieved with low-concentration materials. The solid lines A and B shown in FIG. 8 indicate the range in which the relationship between the strength: Y and the electrical conductivity: X of the thin alloy wire of the present invention is expressed by the above-described formula (2).

[0036] Fig. 9 shows the relationship between the hardness and heat treatment time when a Cu-2wt% -Cu-10wt% Ag alloy was cold worked to a strength of 0.6 and then heat treated at 450 ° C. ! / Speak. The initial hardness is about 70Hv, and when it is cold worked, the hardness increases to about 130-170. By subsequent heat treatment, the hardness decreases with aging time as shown in Fig. 9. The time when this decrease becomes constant is the completion of recrystallization.

[0037] 2% eight ₈ The alloy 20- 30 hours, 3% eight ₈ In alloy 15 20 hours, 4 wt% Ag in the alloys 5-10 hours, in 5 wt% Ag alloy 2-3 hours, 6 wt% Ag alloy And 10wt% Ag is about 1-2 hours. This result shows that the heat treatment temperature force is 50 ° C. When the heat treatment temperature is lower than 450 ° C, the recrystallization completion time is longer, and when the heat treatment temperature is higher than 450 ° C, Become a short time side.

FIG. 10 and FIG. 11 are optical micrographs showing the state of the structure before and after heat treatment of Cu-3 wt% Ag and Cu-5 wt% Ag alloy. Figure 10 (a) shows the structure of a material that was cold worked to a degree of work r? = 0.53 after solution treatment of a 3wt% Ag alloy. Figure 10 (b) shows the microstructure of the cold-worked material after heat treatment at 350 ° CX 1 Oh. In (a) and (b), there is almost no change in organization. FIG. 10 (c) shows the state of the material in the state of FIG. 10 (&) after heat treatment at 450 for 10 hours. As can be seen in Fig. 10 (c), after 450 ° CX 10h heat treatment, the entire sample recrystallizes. The Cu-5wt% Ag alloy is the same as the Cu-3wt% Ag alloy as shown in Figs. 11 (a), 11 (b), and 11 (c). The features of the present invention are well illustrated. Industrial applicability

According to the present invention, production of a high strength, high conductivity, ultrafine copper alloy wire, which was impossible with the conventional method, can be realized in a simple process using existing equipment. In conventional ultrafine wire manufacturing, force that requires annealing several times In the present invention, heat treatment is required only once in all the processes of ultrafine wire manufacturing, and up to ultra-strong steel work areas with a workability r? = 12 or more. Can draw wire. In addition, according to the present invention, the addition of a low concentration of Ag provides a high strength property of 600 MPa or more, further 900 MPa or more, and a high conductivity characteristic of 70% IACS or more, for example, 1200 MPa at 2 wt% Ag. High strength and high conductivity of 80% IACS can be obtained.

Claims

The scope of the claims

[1] In the Cu-Ag alloy thin wire obtained by performing the cold wire drawing force before and after performing the recrystallization heat treatment in a vacuum or an inert gas atmosphere, Machining power in machining Cu-Ag alloy thin wire characterized by being 12 times or more in the subsequent process compared to the previous process.

[2] The Cu—Ag alloy thin wire according to claim 1, wherein the Ag content is 1 to 10 wt%.

[3] A Cu—Ag alloy fine wire, wherein the Cu—Ag alloy fine wire according to claim 1 has an Ag content of 2 to 6 wt%.

[4] The Cu—Ag alloy fine wire according to claim 1, wherein the Ag content is 2 to 3 wt%, and the magnification of the working degree is 18 times or more. Ag alloy thin wire.

[5] Before and after performing recrystallization heat treatment in a vacuum or inert gas atmosphere, the degree of work in the subsequent process is 12 times or more of the degree of work in the previous process. A method for producing Cu-Ag alloy thin wires characterized by

[6] In the method for producing a Cu—Ag alloy fine wire according to claim 5, the Ag content is

1 to: A method for producing a Cu—Ag alloy fine wire, characterized by being LOwt%.

[7] In the method for producing a Cu—Ag alloy fine wire according to claim 5, the Ag content is

A method for producing a Cu—Ag alloy fine wire, characterized in that the content is 2 to 6 wt%.

[8] In the method for producing a Cu—Ag alloy fine wire according to claim 5, the Ag content is

The method for producing a Cu—Ag alloy fine wire, characterized in that it is 2 to 3 wt%, and the magnification of the above-mentioned degree of cache is 18 times or more.