JP5376389B2 - Nitride dispersion strengthened Cu alloy, method for producing the same and conductor wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride-dispersed reinforced copper (Cu) alloy superior in tensile strength and conductivity and its manufacturing method. <P>SOLUTION: The Cu alloy of the invention is a Cu alloy in which fine particles of a nitride are dispersed in Cu or a Cu alloy. This Cu alloy has a tensile strength of 1,000 MPa or higher and a conductivity of 75%IACS or higher. The method of manufacturing the Cu alloy includes a melting step of melting Cu or a Cu alloy by adding a nitride-forming element, a bubbling step of bubbling the melt obtained in the melting step with a gas containing nitrogen, and a solidifying step of solidifying the melt. By this bubbling step, it is possible to nitride the nitride-forming element in the melt to form fine nitride particles, and at the same time, it is possible to easily and uniformly disperse the nitride particles in the melt. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a nitride dispersion strengthened Cu alloy, a method for producing the same, and a conductor wire. In particular, it relates to a nitride dispersion strengthened Cu alloy having excellent tensile strength and electrical conductivity, a method for producing the same, and a conductor wire.

  Cu or Cu alloys are widely used as conductive materials such as lead wires, lead frames, and cables. From the viewpoint of further thinning, miniaturization, large capacity, and high performance of electrical and electronic equipment, There is a need for high conductivity Cu alloys. However, the strength and conductivity of the Cu alloy are in a trade-off relationship, and the conductivity tends to decrease when the strength is increased. Examples of Cu alloys that are generally put into practical use include Cu—Be alloys, Cu—Ti alloys, Cu—Sn alloys, Cu—Cr alloys, and Cu—Zr alloys. For example, the Cu-Be alloy known as high strength among Cu alloys in practical use has a tensile strength of 1000 MPa or more, but its conductivity is less than 50% IACS.

  In addition, there is a Cu-Ag alloy whose strength is improved by adding Ag to Cu without substantially reducing the conductivity of Cu. Cu-Ag alloys have high strength and good electrical conductivity. For example, alloys with a tensile strength of 800 MPa or more have been developed while maintaining the electrical conductivity at 80% IACS or higher.

  Furthermore, it is considered to improve the strength while maintaining the conductivity of the base material by dispersing fine particles of ceramics such as oxides and nitrides in Cu or Cu alloy as the base material. Techniques relating to such a dispersion strengthened Cu alloy are disclosed in Patent Document 1 and Patent Document 2, for example.

  Patent Document 1 discloses a method for producing a nitride dispersion strengthened Cu alloy. Specifically, after melting by adding Zr to Cu, the surface of the molten alloy is irradiated with a high-temperature arc in an atmosphere containing nitrogen, and the molten alloy is heated and nitrogen in the atmosphere and Zr in the molten alloy To nitrify Zr. Then, the molten alloy is solidified with the nitride of Zr dispersed in the molten alloy.

  Patent Document 2 discloses a Cu alloy containing a Cu—Cr alloy as a main component and dispersing oxides, nitrides, and the like of Cr, Ti, and Al, and a method for manufacturing the same. In Patent Document 2, when manufacturing using a casting method, after adding Cr, Ti, Al, and Ag to Cu in an argon atmosphere and dissolving, molten argon gas, oxygen gas, etc. for degassing and oxide formation Bubbling from below. Next, after agglomerating at a reduced temperature, the agglomerated material is rapidly cooled under a 3.5 bar nitrogen atmosphere in order to perform internal diffusion of nitrogen.

JP-A-5-098371 JP-A-8-218136

  However, Be is very toxic and has safety issues. The Cu-Ag alloy is a high-strength and high-conductivity Cu alloy that has an excellent balance between strength and electrical conductivity. However, because it uses Ag, which is a rare metal, its cost performance is low. It must be said that it is difficult to use as a general-purpose product.

The Cu alloy obtained by the manufacturing method of Patent Document 1 has a hardness of 145 Hv and a conductivity of 88% IACS. The hardness and tensile strength are almost proportional, and the value with 1/3 hardness (Hv) is almost equal to the tensile strength (kgf / mm ² ), so the tensile strength of this alloy is estimated to be around 473 MPa. . Certainly this alloy has good electrical conductivity, but not enough strength. In the method of Patent Document 1, Zr is nitrided by reacting nitrogen in the atmosphere and Zr in the molten alloy on the surface of the molten alloy irradiated with the high-temperature arc. For this reason, it is difficult to surely disperse the nitride fine particles uniformly in the Cu alloy, which is considered to be a factor that a sufficient strength cannot be obtained. Moreover, in the manufacturing method of patent document 1, in order to utilize a high temperature arc, for example, a multi-phase multi-electrode plasma arc generator is required, and work becomes a cause and cost increase.

  Next, the tensile strength of the Cu alloy of Patent Document 2 is 523 MPa, and the conductivity is 88% IACS. Although this Cu alloy has good electrical conductivity as well as the Cu alloy of Patent Document 1, it does not have sufficient strength. In the method of Patent Document 2, internal diffusion of nitrogen is performed by cooling the agglomerate in a pressurized nitrogen gas atmosphere. Therefore, since nitrogen is introduced into the alloy from the alloy surface, it is difficult to uniformly disperse the nitride fine particles in the Cu alloy. Further, in the method of Patent Document 2, it is necessary to perform rapid solidification in a pressurized nitrogen gas atmosphere, and the operation is complicated.

  The present invention has been made in view of the above circumstances, and one of its purposes is a dispersion-strengthened Cu alloy having a high strength and high conductivity excellent in balance between strength and conductivity, in which nitride fine particles are dispersed. Is to provide.

  Another object of the present invention is to provide a method for producing a dispersion strengthened Cu alloy which improves the conventional production method and forms fine nitride particles and can be uniformly dispersed in a base material. There is.

  Another object of the present invention is to provide a conductor wire using a nitride dispersion strengthened Cu alloy having high strength and high conductivity.

  The Cu alloy of the present invention is a Cu alloy in which fine particles of nitride are dispersed in Cu or a Cu alloy. The alloy has a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more.

  Conventionally, such a Cu alloy having an excellent balance between strength and electrical conductivity could be obtained by adding Ag to Cu. However, the Cu-Ag alloy has a low cost performance because it uses Ag, which is a rare metal, and it has been difficult to use such a Cu alloy for general-purpose products. The Cu alloy of the present invention has a high strength and high conductivity Cu that achieves a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more by dispersing nitride fine particles in the base material Cu or Cu alloy. It is an alloy. The base material is not necessarily limited to Cu alone, but may be a Cu alloy such as a Cu—Ag alloy, a Cu—Sn alloy, a Cu—Cr alloy, or a Cu—Zr alloy. For example, when a Cu—Ag alloy is selected as the base material, it is possible to obtain a Cu alloy with high strength and high conductivity having equivalent or better performance with a smaller amount of Ag added than before.

  The nitride particles present in the Cu alloy of the present invention preferably have an average particle size of 0.1 μm or less and are dispersed at intervals of an average of 1 μm or less.

  With such a configuration, it is easy to obtain a Cu alloy having a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. The interval is the distance between the center points of adjacent particles.

  The element forming the nitride is preferably at least one element selected from Zr, Ti, Ce, Al, Ta, B, V, and Nb.

  The elements listed above are elements that easily form nitrides compared to Cu, and the nitrides are stable and have high hardness and high strength. Therefore, since such nitride fine particles are dispersed in the base material, the strength can be further improved while maintaining the conductivity of the base material.

  The volume ratio of the nitride contained in the Cu alloy of the present invention is preferably 0.01 vol% or more and 20 vol% or less. The specific composition of the Cu alloy of the present invention when Cu or a Cu alloy is used as the base material contains a nitride-forming element and nitrogen in the following composition range when expressed in terms of weight ratio wt%, and the balance Are preferably Cu and inevitable impurities.

(A) When using Zr
Zr: 0.01 to 15 wt%, N: 0.001 to 2.5 wt%.
(B) When using Ti
Ti: 0.01 to 10 wt%, N: 0.001 to 3.0 wt%.
(C) When using Ce
Ce: 0.01 to 15 wt%, N: 0.001 to 1.5 wt%.
(D) When using Al
Al: 0.001 to 6 wt%, N: 0.001 to 3.0 wt%.
(E) When using Ta
Ta: 0.01-30 wt%, N: 0.001-2.5 wt%.
(F) When using B
B: 0.001 to 4 wt%, N: 0.001 to 5.5 wt%.
(G) When using V
V: 0.01 to 12 wt%, N: 0.001 to 3.5 wt%.
(H) When Nb is used
Nb: 0.01 to 17 wt%, N: 0.001 to 3.0 wt%.

  The nitride-forming elements contained in the Cu alloy of the present invention include those that form nitrides, those that do not form nitrides and are precipitated in Cu alloys, those that are solid-solved in Cu alloys, etc. All together. If the nitride-forming element is less than the minimum content, sufficient strength tends not to be obtained, and if it exceeds the maximum content, the conductivity tends to be greatly reduced. Most of N is considered to form nitride by reacting with a nitride-forming element without being dissolved in Cu. The Cu alloy of the present invention may contain a plurality of elements selected from the above-mentioned nitride forming elements in the Cu alloy. In this case, the total content of nitride-forming elements is preferably adjusted so that the total content of nitrides formed is 20 vol% or less.

  Further, the nitride is preferably formed by bubbling a gas containing nitrogen.

  By bubbling nitrogen-containing gas into the molten metal with the nitride-forming element added to the base material, fine nitride particles are formed, and the stirring particles uniformly disperse the nitride particles in the molten metal. . Therefore, the Cu alloy obtained by solidifying the molten metal is in a state in which nitride particles are uniformly dispersed. The Cu alloy of the present invention can be easily manufactured by using a simple means such as bubbling, and the manufacturing cost can be reduced.

  The Cu alloy production method of the present invention is a Cu alloy production method in which fine particles of nitride are dispersed in Cu or a Cu alloy as a base material, and has the following configuration. The method of the present invention includes a melting step in which an element that easily forms a nitride is added to Cu or a Cu alloy and melted, a bubbling step in which a gas containing nitrogen is bubbled into the molten metal obtained by the melting step, and the molten metal. A coagulation process for coagulation.

  The production method of the Cu alloy of the present invention is different from the conventional production method in that bubbling means is mainly used for forming nitride particles. According to the above configuration, fine nitride particles can be formed and can be easily and uniformly dispersed in the base material. By using this production method, it is possible to produce a Cu alloy having a high strength and high conductivity having a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more.

  Hereafter, the manufacturing method of this invention Cu alloy is demonstrated in detail.

  First, a predetermined amount of Cu or Cu alloy as a base material and an element that easily forms a nitride are prepared. Elements that easily form nitrides include, for example, Zr, Ti, Ce, Al, Ta, B, Mg, Hf, V, Nb, etc. periodic table groups 2a, 3a, 4a, 5a and At least one element selected from Group 3b. In particular, it is preferable that the standard free energy of formation of nitride per 1 mol of nitrogen gas is an element of −100 kJ or less at 1100 ° C., more preferably −200 kJ or less at 1100 ° C. Further, the blending ratio of the nitride-forming element is preferably set to the following value, for example.

(A) When using Zr
Zr: 0.02 to 50 wt%, balance is Cu or Cu alloy.
(B) When using Ti
Ti: 0.01-20wt%, the balance is Cu or Cu alloy.
(C) When using B
B: 0.001 to 5 wt%, balance is Cu or Cu alloy.
(D) When using V
V: 0.07 to 15 wt%, the balance being Cu or Cu alloy.
(E) When Nb is used
Nb: 0.10 to 20 wt%, balance is Cu or Cu alloy.

  Next, after heating these raw materials prepared in the melting step to a molten state, a gas containing nitrogen is bubbled from the lower part of the molten metal. The gas containing nitrogen to be bubbled may be only nitrogen gas or a mixed gas of an inert gas such as argon gas and nitrogen gas. When the mixed gas is used, the mixed gas preferably contains 30% by volume or more of nitrogen gas, and more preferably contains 50% by volume or more. By increasing the ratio of nitrogen gas, the reaction between the nitride-forming element and nitrogen can be promoted. The flow rate of the gas to be bubbled and the bubbling time may be appropriately determined according to the amount of the molten metal, the amount of the added nitride forming element, and the like. By this bubbling step, the nitride forming element in the molten metal is nitrided to form fine nitride particles, and the nitride particles can be easily and uniformly dispersed in the molten metal. The atmosphere for melting and bubbling may be air, but is preferably an inert gas such as nitrogen gas or argon gas in order to suppress the generation of slag (oxide). More preferably, a mixed gas in which 5 to 15 vol% of hydrogen gas is added to the above inert gas in order to drive out oxygen inevitably present.

  In the bubbling step, the temperature of the molten metal is preferably set to a melting point of Cu or higher, and more preferably set to 1100 ° C. or higher.

  By setting the temperature of the molten metal to 1100 ° C. or higher, homogenization of the molten metal can be promoted, and the reaction between the nitride-forming element and nitrogen can be promoted. Note that when the temperature of the molten metal is higher than the melting point of the nitride, since the nitride particles tend to be coarse, the molten metal temperature is preferably set to be equal to or lower than the melting point of the nitride.

  In the bubbling step, the size of the gas bubbles supplied to the molten metal is preferably 10 mm or less in diameter, more preferably 5 mm or less in diameter, and the gas flow rate is 10 ml / min or more per 1 kg of molten metal. Is preferable, and more preferably 50 ml / min or more.

  By using fine bubbles having a diameter of 10 mm or less, the reaction between the nitride-forming element and nitrogen can be promoted. Furthermore, if the bubble size is reduced to 5 mm or less, the surface area of the entire bubble increases, and the reaction between the nitride-forming element and nitrogen can be further promoted. Further, by setting the gas supply rate to 10 ml / min or more per 1 kg of molten metal, it is possible to easily and uniformly disperse the nitride particles in the molten metal by the stirring action, and the reaction between the nitride forming element and nitrogen. Can be promoted. Furthermore, if the gas supply rate is increased to 50 ml / min or more per 1 kg of the molten metal, the stirring action is improved, and the nitride particles are more easily and uniformly dispersed in the molten metal. This reaction can be further promoted. The bubble size is adjusted by, for example, the opening diameter of a nozzle from which gas is ejected. For example, by attaching porous ceramics to the opening of the nozzle, the size of the bubbles can be made smaller than the opening diameter of the nozzle. It is also possible to adjust the bubble size by adjusting the opening diameter of the nozzle and the stirring speed by stirring the molten metal with a stirring blade or the like. With the shearing force generated by the rotation of the stirring blade, the bubbles supplied from the nozzle can be divided and made finer, and the size of the bubbles can be made smaller than the opening diameter of the nozzle.

  In the solidification step, the molten metal is solidified with the nitride particles uniformly dispersed.

  In the solidification step, the molten metal is preferably solidified at a cooling rate of 10 ° C./min or more, more preferably at a cooling rate of 60 ° C./min or more.

  By solidifying at a cooling rate of 10 ° C / min or more, the molten metal can be solidified with the nitride particles uniformly dispersed in the molten metal, and the resulting Cu alloy has uniform nitride particles. It becomes a distributed state. Furthermore, if the cooling capacity is increased and solidification is performed at a cooling rate of 60 ° C./min or more, the molten metal can be solidified while the nitride particles are more uniformly dispersed in the molten metal, and the obtained Cu The alloy is in a state in which nitride particles are more uniformly dispersed. Such a cooling rate can be realized by, for example, water-cooling solidification.

  In the solidification step, it is preferable to continuously cast the molten metal.

  It becomes possible to improve the productivity of Cu alloy by continuous casting.

  The Cu alloy of the present invention can be suitably used as a conductor wire for use in electric / electronic devices and the like by forming into a wire shape. In particular, it is desirable that the nitride particles present in the Cu alloy formed on the wire have an average particle size of 0.1 μm or less and the particles are dispersed at an average interval of 1 μm or less.

  Such a wire is a high-strength and high-conductivity wire having a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. Therefore, it is possible to contribute to further reduction in thickness, size, and capacity of electric / electronic devices. In particular, since it has high conductivity and is excellent in flexibility and twistability, it can be suitably used for movable parts of automobiles, devices and robots.

  The Cu alloy of the present invention and the manufacturing method thereof have the following effects.

  The Cu alloy of the present invention has a high strength and high conductivity with a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more because nitride particles are dispersed in Cu or Cu alloy. Cu alloy. The Cu alloy of the present invention does not need to use Be as an additive element at all and has high manufacturing safety. Further, it is not necessary to use expensive silver, and the manufacturing cost is low. Even if a Cu-Ag alloy is used as the base material, the amount of Ag to be added is smaller than before, and the manufacturing cost can be kept low.

  A conductor wire obtained by forming such a Cu alloy into a wire shape can be suitably used for electrical and electronic equipment. In particular, since it has sufficient tensile strength, it can also be used in places such as a movable part of a robot. In addition, it has high conductivity, so that power consumption of the device can be suppressed.

  In addition, the Cu alloy manufacturing method of the present invention uses simple means such as bubbling to form nitride particles, is easy to work, and can reduce manufacturing costs. Further, the bubbling also has an effect of stirring the molten metal, so that nitride particles can be uniformly dispersed in the molten metal.

  Embodiments of the present invention will be described below.

<Preparation of Cu alloy and its evaluation>
Various Cu alloys were produced using the method for producing a Cu alloy of the present invention, and the composition, mechanical properties (tensile strength), and electrical properties (conductivity) of each alloy were examined.

Example 1
A nitride dispersion-strengthened Cu alloy using Cu as a base material and Zr as a nitride-forming element was prepared.

  A specific manufacturing method will be described.

  Oxygen-free Cu980g and Cu-Zr alloy (Zr content 50wt%) 20g were prepared. These raw materials were put in an alumina crucible and heated to 1175 ° C in an electric furnace to be in a molten state. Thereafter, while keeping the temperature of the molten metal constant, pure nitrogen gas was bubbled from the lower portion of the molten metal to nitride the molten Zr and to stir the molten metal. The bubbling conditions were a pressure of 0.1 MPa and a flow rate of 200 ml / min. The nozzle used for bubbling was a nozzle with an opening diameter of 4.5 mm so that the bubble size was 4.5 mm in diameter. The atmosphere during melting and bubbling was a mixed gas of 90 vol% nitrogen and 10 vol% hydrogen in order to prevent oxidation of the raw material. After performing this bubbling operation for 5 hours, 10 to 20 g of molten metal was collected from the vicinity of the center of the molten metal with a quartz pipette and immediately poured into the water together with this pipette to solidify the molten metal. The cooling rate at this time was about 600 ° C./min. The solidified Cu alloy was taken out from this pipette, and the work of removing the quartz adhering to the surface was performed to obtain a cast ingot of Cu alloy. The obtained Cu alloy was designated as Sample 1.

  Further, as a sample for comparison, the same raw material as that of Sample 1 was melted, and then the molten metal was immediately solidified without bubbling to produce a Cu alloy. The melting operation and the solidification operation were performed in the same manner as the preparation of Sample 1. The obtained Cu alloy was designated as Sample 2.

  Further, as another comparative sample, 1000 g of oxygen-free Cu was melted, and after bubbling was performed for 5 hours, the molten metal was solidified to produce a Cu alloy. The melting operation, bubbling operation, and solidification operation were performed in the same manner as the preparation of Sample 1. The obtained Cu alloy was designated as Sample 3.

  Table 1 shows the compositions of Sample 1, Sample 2, and Sample 3.

  Next, each of the obtained sample 1, sample 2 and sample 3 was processed to produce a round bar specimen (Cu alloy wire). Specifically, a Cu alloy wire with a diameter of φ3.26 mm was produced from a Cu alloy cast ingot with a diameter of φ4.5 mm by swaging each sample at a surface reduction rate of 50%. Table 2 shows the tensile strength and electrical conductivity examined for each specimen.

  Sample 1 had a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. In contrast, Sample 2 had a tensile strength of 496 MPa and had only a tensile strength of about 40% of Sample 1. Sample 3 had a tensile strength of 353 MPa, which was only about 30% that of Sample 1. This is considered to be due to the influence of the nitrogen content, and this nitrogen is considered to react with Zr to form ZrN (zirconium nitride). Therefore, the present inventors dissolved the metal component in the sample using a bromine methanol solution for each sample, recovered the non-metallic component remaining without being dissolved, dried, and then X-rays of the component Structural analysis by diffraction was performed. It was confirmed that a plurality of ZrN particles were formed in the Cu alloy of Sample 1. In addition, the inventors have obtained a microscopic image of the cross section of the sample 1 with a scanning electron microscope and image-processed to model the ZrN particles in the Cu alloy into a circle equal to the area, The average particle diameter and the average interval of ZrN were determined with the diameter of this circle as the particle size of ZrN particles and the distance between the centers of the circles as the interval between ZrN particles. Then, the present inventors confirmed that this ZrN was (1) formed as fine particles and (2) was uniformly dispersed in the Cu alloy of Sample 1. Specifically, the ZrN particles had an average particle size of 0.08 μm, and the particles were dispersed at an average interval of 0.41 μm.

(Example 2)
A nitride dispersion-strengthened Cu alloy using Cu as the base material and Ti as the nitride-forming element was prepared.

  Specifically, oxygen-free Cu980 g and Cu-Ti alloy (Ti content 50 wt%) 20 g were prepared, and a Cu alloy was produced by the same method as Sample 1 produced in Example 1. The obtained Cu alloy was designated as Sample 4. Moreover, the sample 4 was processed similarly to the sample 1, and the test body (Cu alloy wire) was produced. Table 3 shows the composition of Sample 4 and the tensile strength and electrical conductivity of the specimen.

  Sample 4 had a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. The present inventors conducted a structural analysis by X-ray diffraction of the nonmetallic component in the sample 4 in the same manner as the sample 1, and a plurality of TiN (titanium nitride) particles were formed in the Cu alloy of the sample 4. Confirmed that it has been. In addition, the present inventors acquired a microscopic image of the cross section of the sample 4 as in the case of the sample 1 and processed the image, whereby (1) the TiN is formed as fine particles, (2) It was confirmed that the Cu alloy of Sample 4 was uniformly dispersed. Specifically, TiN particles had an average particle size of 0.08 μm, and the particles were dispersed at an average interval of 0.52 μm.

(Example 3)
A nitride dispersion strengthened Cu alloy was prepared using Cu as the base material and B as the nitride-forming element.

  Specifically, 900 g of oxygen-free Cu and 100 g of Cu-B alloy (B content 2 wt%) were prepared, and a Cu alloy was produced by the same method as Sample 1 produced in Example 1. The obtained Cu alloy was designated as Sample 5. Further, the sample 5 was processed in the same manner as the sample 1 to prepare a test body (Cu alloy wire). Table 4 shows the composition of Sample 5 and the tensile strength and conductivity of the test specimen.

  Sample 5 had a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. The present inventors conducted a structural analysis by X-ray diffraction of the nonmetallic component in the sample 5 in the same manner as in the sample 1, and a plurality of BN (boron nitride) particles were formed in the Cu alloy of the sample 5. Confirmed that it has been. In addition, the present inventors acquired a microscopic image of the cross section of the sample 5 and processed the image in the same manner as the sample 1, whereby (1) the BN was formed as fine particles, (2) It was confirmed that the sample was uniformly dispersed in the Cu alloy of Sample 5. Specifically, the BN particles had an average particle size of 0.09 μm, and the particles were dispersed at an average interval of 0.4 μm.

  As described above, Sample 1, Sample 4 and Sample 5, which are the inventive Cu alloys of the present invention, are high strength and high conductivity Cu alloys having a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. I was able to confirm. In addition, it was confirmed that nitride fine particles such as ZrN, TiN, and BN were uniformly dispersed in these alloys.

Example 4
Using the same raw material as Sample 1, a nitride dispersion strengthened Cu alloy was produced by changing the bubbling conditions and the cooling rate during solidification.

[Implementation after changing bubbling conditions]
Cu alloy with different bubbling conditions after bubbling work for 20 hours and 200 hours respectively at a gas flow rate of 50 ml / min and 5 ml / min per kg of molten metal for bubbling work, and then solidifying each molten metal Was made. Except for these bubbling conditions, the melting, bubbling, and solidification operations were performed in the same manner as Sample 1. The obtained Cu alloys were used as Sample 6 and Sample 7, and were processed in the same manner as Sample 1 to prepare specimens (Cu alloy wires). Table 5 shows the compositions of Sample 6 and Sample 7, and the tensile strength and conductivity of the test specimens.

  Sample 6 had a tensile strength of 1000 MPa or more and an electrical conductivity of 75% IACS or more, while Sample 7 had a tensile strength of 426 MPa, which was only about 35% of that of Sample 1. Therefore, the present inventors investigated the state of ZrN particles by acquiring microscopic images of the cross sections of Sample 6 and Sample 7 and performing image processing in the same manner as Sample 1. As a result, ZrN particles were uniformly dispersed in Sample 6 as in Sample 1, but ZrN particles were nonuniformly dispersed in Sample 7. From this, it is considered that Sample 7 did not obtain a sufficient stirring action.

[Implementation by changing the cooling rate during solidification]
Different cooling rates are obtained by performing the melting, bubbling, and solidification operations in the same manner as Sample 1, except that the cooling rates during solidification are 60 ° C / min and 5 ° C / min. Cu alloys were prepared respectively. The obtained Cu alloys were designated as Sample 8 and Sample 9, and processed in the same manner as Sample 1 to prepare test bodies (Cu alloy wires). Table 6 shows the compositions of Sample 8 and Sample 9, and the tensile strength and conductivity of the test specimens.

  Sample 8 had a tensile strength of 1000 MPa or more and an electrical conductivity of 75% IACS or more, while Sample 9 had a tensile strength of 413 MPa, which was only about 35% of that of Sample 1. Therefore, the present inventors investigated the state of ZrN particles by acquiring microscopic images of the cross sections of the sample 8 and the sample 9 and performing image processing in the same manner as the sample 1. As a result, the sample 8 had the ZrN particles uniformly dispersed as in the sample 1, but the sample 9 had the ZrN particles dispersed non-uniformly. From this, it is considered that the dispersion state of the ZrN particles became non-uniform because the cooling rate of Sample 9 was slow during solidification.

  Next, a Cu alloy using V and Nb, which are elements having a standard free energy of formation of nitride per 1 mol of nitrogen gas of −100 kJ or less and more than −200 kJ at 1100 ° C., was investigated.

(Example 5)
A nitride dispersion strengthened Cu alloy was prepared using Cu as the base material and V as the nitride-forming element.

  Specifically, oxygen-free Cu980 g and Cu-V alloy (V content 50 wt%) 20 g were prepared, and a Cu alloy was produced by the same method as Sample 1 produced in Example 1. The obtained Cu alloy was designated as Sample 10. Further, the sample 10 was processed in the same manner as the sample 1 to prepare a test body (Cu alloy wire). Table 7 shows the composition of Sample 10 and the tensile strength and conductivity of the test specimen.

  Sample 10 had a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. The present inventors conducted a structural analysis of the sample 10 by X-ray diffraction of the nonmetallic component in the same manner as the sample 1, and a plurality of VN (vanadium nitride) particles were formed in the Cu alloy of the sample 10. Confirmed that it has been. In addition, the present inventors obtain a microscope image of a cross section of the sample 10 and perform image processing in the same manner as the sample 1, and (1) the VN is formed as fine particles, (2) It was confirmed that the sample was uniformly dispersed in the Cu alloy of Sample 10. Specifically, VN particles had an average particle size of 0.08 μm, and the particles were dispersed at an average interval of 0.49 μm.

(Example 6)
A nitride dispersion strengthened Cu alloy was prepared using Cu as the base material and Nb as the nitride-forming element.

  Specifically, oxygen-free Cu980 g and Cu-Nb alloy (Nb content 50 wt%) 20 g were prepared, and a Cu alloy was produced by the same method as Sample 1 produced in Example 1. The obtained Cu alloy was designated as Sample 11. Further, the sample 11 was processed in the same manner as the sample 1 to prepare a test body (Cu alloy wire). Table 8 shows the composition of Sample 11 and the tensile strength and conductivity of the test specimen.

  Sample 11 had a tensile strength of 1000 MPa or more and a conductivity of 75% IACS or more. The present inventors conducted a structural analysis by X-ray diffraction of the nonmetallic component in the sample 11 in the same manner as the sample 1, and formed a plurality of NbN (niobium nitride) particles in the Cu alloy of the sample 11. Confirmed that it has been. In addition, the present inventors acquired a microscopic image of the cross section of the sample 11 as in the case of the sample 1 and processed the image, whereby (1) the NbN is formed as fine particles, (2) It was confirmed that the sample 11 was uniformly dispersed in the Cu alloy. Specifically, the NbN particles had an average particle size of 0.08 μm, and the particles were dispersed at an average interval of 0.39 μm.

  As shown in Examples 5 and 6, Samples 10 and 11 using V and Nb as nitride-forming elements are Cu alloys having high strength and high conductivity, and are free of standard generation of nitrides. It was confirmed that even if the energy is V or Nb exceeding −200 kJ at 1100 ° C., it reacts efficiently with nitrogen to form nitride particles. It was also confirmed that nitride fine particles such as VN and NbN were uniformly dispersed in these alloys.

<Production of conductor wire and its evaluation>
Next, each of the specimens of Sample 1, Sample 4, Sample 5, Sample 10, and Sample 11 was formed into a wire shape. Specifically, a conductor wire having a diameter of φ0.1 mm was produced from a Cu alloy wire having a diameter of φ3.26 mm by performing wire drawing at a surface reduction rate of 99.9%. Conductor wire produced using the Cu alloy of Sample 1 is Wire 1, Conductor wire produced using the Cu Alloy of Sample 4 is Wire 2, Conductor wire produced using the Cu alloy of Sample 5 is Wire 3, Sample 10 The conductor wire produced using the Cu alloy of No. 4 was designated as wire 4, and the conductor wire produced using the Cu alloy of Sample 11 was designated as wire 5. Table 9 shows the results of measuring the tensile strength and conductivity of each of the wires 1 to 5. As a comparative example, the results of measuring the tensile strength and conductivity of a conductor wire made of Cu-0.3Sn (Cu alloy containing 0.3 wt% Sn) that is generally used are also shown.

  The wires 1 to 5 obtained by molding the Cu alloy of the present invention all had a high conductivity of 75% IACS or higher, and in particular, had a tensile strength of 1000 MPa or higher. These were about twice the tensile strength of the Cu-0.3Sn wire used in the comparative example. Furthermore, when the present inventors acquired a microscopic image of the cross section of the wires 1 to 5 with a scanning electron microscope and confirmed by performing image processing, the average particle size of the nitride particles present in each alloy was The average particle size was 0.05 μm, and the particles were dispersed at an average interval of 0.3 μm.

  The Cu alloy of the present invention has both properties such as high strength and high conductivity, and can be suitably used as a lead wire, a lead frame, and a cable used in automobiles, electrical / electronic devices, robots, and the like.

  Moreover, the manufacturing method of this invention Cu alloy can manufacture the above-mentioned Cu alloy easily.

Claims (8)

A dispersion strengthened Cu alloy in which nitride is dispersed in Cu or Cu alloy,
It is a molten alloy that solidifies molten metal,
The nitride particles have an average particle size of 0.1 μm or less, and the particles are dispersed at an average interval of 1 μm or less,
Dispersion strengthened Cu alloy characterized in that the tensile strength of this alloy is 1000 MPa or more and the electrical conductivity is 75% IACS or more.   The dispersion strengthened Cu alloy according to claim 1, wherein the content of the nitride is 0.01 vol% or more and 20 vol% or less.   3. The dispersion according to claim 1, wherein the element forming the nitride is an element selected from at least one of Zr, Ti, Ce, Al, Ta, B, V, and Nb. Reinforced Cu alloy. A method for producing a dispersion strengthened Cu alloy in which nitride is dispersed in Cu or a Cu alloy,
A melting process in which an element that easily forms nitride is added to Cu or a Cu alloy and melted;
A bubbling step of bubbling a gas containing nitrogen in the molten metal obtained by the melting step;
A solidification process for solidifying this molten metal at a cooling rate of 10 ° C / min or more,
In the bubbling step, the size of the gas bubbles supplied to the molten metal is 10 mm or less in diameter, and the flow rate of the gas is 10 ml / min or more per 1 kg of the molten metal,
In the dispersion strengthened Cu alloy obtained by these processes ,
The average particle size of the nitride particles is 0.1 μm or less, and the particles are dispersed at an average interval of 1 μm or less,
A method for producing a dispersion strengthened Cu alloy, characterized by having a tensile strength of 1000 MPa or more and an electrical conductivity of 75% IACS or more.   The method for producing a dispersion-strengthened Cu alloy according to claim 4, wherein in the bubbling step, the temperature of the molten metal is set to 1100 ° C or higher.   6. The method for producing a dispersion strengthened Cu alloy according to claim 4, wherein the molten metal is continuously cast in the solidification step. The dispersion according to any one of claims 4 to 6 , wherein in the melting step and the bubbling step, the atmosphere is a mixed gas obtained by adding 5 vol% or more and 15 vol% or less of hydrogen gas to an inert gas. Manufacturing method of reinforced Cu alloy. It is formed by drawing the dispersion strengthened Cu alloy according to any one of claims 1 to 3,
Nitride particles present in a dispersion strengthened Cu alloy formed on a wire have an average particle size of 0.1 μm or less, and the particles are dispersed at an average interval of 1 μm or less. Wire.