JP2008081834A - High-strength, high-conductivity dual phase copper alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-strength, high-conductivity dual phase copper alloy having excellent strength and bending workability. <P>SOLUTION: The rolled material has a composition comprising, by mass, 3 to 15% Ag, and in which one or more kinds of precipitates selected from the group consisting of Fe, Cr and Fe-P are precipitated into a Cu mother phase, and also, the total concentration composing the precipitates in the alloy is 0.1 to <2%, and the balance Cu with inevitable impurities, has a structure composed of the Cu mother phase and the second phase, and has a 0.2% proof stress of ≥800 MPa. The grain diameter of the precipitates is 20 to 100 nm, and the thickness of the second phase viewed from the cross-section orthogonal to the rolling direction is ≤1 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a two-phase copper alloy that is excellent in strength and conductivity and can be suitably applied to, for example, a spring material for electronic equipment.

Spring materials (connector materials) for electrical and electronic equipment such as terminals, connectors, switches, and relays are required to have excellent spring characteristics, bendability, and conductivity. Conventionally, phosphor bronze has been used. High-strength, high-conductivity alloys have been developed in response to demands for further miniaturization of electronic components.
In addition, the generation of Joule heat increases with the increase in electric current of electric and electronic devices, and the temperature of the spring material is required for the connector mounted on the vehicle, because of the influence of ambient temperature. For example, when the heat resistance is low, the contact pressure decreases due to long-term use, leading to defects in contact failure.
In general, when a strengthening element is added to Cu to increase the strength, the electrical conductivity decreases, while on the other hand, increasing the Cu purity has a relationship of decreasing the strength to increase the electrical conductivity. Therefore, an alloy system (double phase alloy) was developed in which the second phase was crystallized in the Cu matrix. This alloy has a second phase dispersed in a fiber form by strong processing and has the same strength as phosphor bronze, but the parent phase is Cu, so the conductivity is 60% IACS (international annealed copper standard, annealed) A highly conductive material exceeding the ratio of electrical conductivity to standard annealed copper has been obtained. As this multiphase alloy system, Cu—Cr, Cu—Fe, Cu—Nb, Cu—W, Cu—Ta, Cu—Ag and the like are known (for example, see Patent Documents 1 to 7).

  On the other hand, in a multiphase alloy, the rolled Ag phase is divided and pinched-off by a heat treatment at about 400 ° C., so that the heat resistance of the multiphase alloy is low. On the other hand, a technique for improving heat resistance by dispersing particles such as carbide in a Cu matrix is known (see, for example, Patent Document 8).

JP-A-9-249925 Japanese Patent Laid-Open No. 10-140267 Japanese Patent Laid-Open No. 10-8166 Japanese Patent Laid-Open No. 06-192801 Japanese Patent Laid-Open No. 06-279894 Japanese Patent Laid-Open No. 10-53824 Japanese Patent Laid-Open No. 10-349085 JP 2000-96163 A

By the way, in the case of the said prior art, means, such as drawing and rolling, are used as a strong processing method for extending | stretching a 2nd phase to a fiber form. In this case, since the wire is only required to have a strength in the wire direction, sufficient strength can be ensured only by drawing and stretching the second phase.
In addition, the techniques described in Patent Documents 4 to 7 are produced by using the above-mentioned multiphase alloy to produce a rolled material. When the second phase is sufficiently stretched in the parallel direction of rolling to become fibrous, It is described that the strength of the rolled material is also improved as rolling proceeds in the longitudinal direction.

  However, these documents do not describe bending workability. For example, when a connector is taken from the rolled material, it is customary to punch the connector in such a way that the connector is aligned in the longitudinal direction of the rolled material and each pin extends in the width direction of the rolled material. When bending in a perpendicular direction, if the bending workability in this direction is low, cracks may occur when bending the connector. The problem with such a multi-phase alloy is what the present inventors have paid attention to for the first time, and as a result of investigating the bending workability in the direction perpendicular to the rolling of the conventional multi-phase alloy, the bending workability is It turned out to be very bad.

On the other hand, in the case of the technique described in Patent Document 8, heat resistance (so-called semi-softening temperature) against heat treatment for 1 hour has been confirmed. However, when the spring material is used for an actual product, it can be used for a long time (high temperature or room temperature). Stress relaxation characteristics) Heat resistance is required. For example, in the case of an electronic device such as a CPU socket, the heat resistance test at 150 ° C. × 1000 hours (stress relaxation test described later) is often used as a reference.
It is considered that the characteristics different from the evaluation test of the semi-softening temperature and the stress relaxation test are evaluated. Specifically, when a plate material such as a copper foil is bonded to a resin or cured (heat treatment), heat treatment is performed at about 400 ° C. for about 1 hour, and the strength at that time is important. Therefore, the semi-softening temperature can be given as a reference for the softening characteristics. In order to improve this semi-softening property, it is effective to suppress the movement of dislocations or raise the recrystallization temperature. Pinning dislocations by precipitates and increasing the recrystallization temperature by added elements. Becomes effective.
On the other hand, in a copper alloy of a spring material such as a CPU socket, the strength is softened due to the generation of Joule heat due to a large current, and the contact pressure may be reduced. Therefore, it is necessary to evaluate the relaxation rate of the contact pressure (stress) at a constant temperature. In principle, stress relaxation characteristics are not related to semi-softening characteristics, and the main cause of sag is the grain boundary (interface) slip of crystal grains. In general, precipitates are effective in suppressing this interface slip. It is thought that.
However, no investigation has been made on the stress relaxation rate of conventional multiphase alloys, and there has been no improvement. As a result of investigations by the present inventors, all of the conventional multiphase alloys have low stress relaxation rates (inferior long-term heat resistance). )It has been found.

As described above, strong processing is required to increase the strength by finely dispersing the second phase, but the bending workability decreases as the strong processing is performed. In addition, if annealing is performed to ensure bending workability, the fibrous Ag phase becomes spheroidized and the strength decreases. Therefore, it has been difficult to achieve both strength and bending workability.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-strength, high-conductivity two-phase copper alloy excellent in strength and bending workability.

As a result of various studies, the present inventors have found that in a rolled material of an alloy system in which a second phase mainly composed of Ag is crystallized in a Cu matrix (hereinafter referred to as “double phase alloy”), As seen, it was found that the strength and the bending workability were improved by reducing the thickness and interval of the second phase and further depositing precipitates.
That is, in the multiphase alloy of the present invention, the one corresponding to the grain boundary is the interface between the parent phase and the second phase, and therefore precipitates are effective for suppressing the slip at this interface. As described above, since the precipitate is effective for both the semi-softening property and the stress relaxation property, the precipitation type copper alloy of the present invention can improve both the semi-softening property and the stress relaxation property.

  In order to achieve the above object, the high-strength and highly-conductive two-phase copper alloy of the present invention contains 3% or more and 15% or less of Ag by mass%, and is selected from the group of Fe, Cr and Fe-P. One or more kinds of precipitates are precipitated in the Cu matrix, and the total concentration of the elements constituting the precipitates in the alloy is 0.1% or more and less than 2%, and the remainder consists of Cu and unavoidable impurities. It is a rolled material having a 0.2% proof stress of 800 MPa or more consisting of a parent phase and a second phase, the grain size of the precipitate is 20 to 100 nm, and the thickness of the second phase is 1 μm when viewed from the cross section perpendicular to the rolling It is excellent in the following bending workability.

When viewed from a cross section perpendicular to rolling, the interval between the adjacent second phases is preferably 3 μm or less.
Furthermore, it is preferable to contain a total of 0.01% or more and 0.2% or less of one or more additive elements selected from the group consisting of Sn, Mg and Ti.

  According to the present invention, a high-strength and highly conductive two-phase copper alloy having excellent strength and bending workability can be obtained.

  Embodiments of the high-strength, high-conductivity two-phase copper alloy according to the present invention will be described below. In the present invention, “%” means “% by mass” unless otherwise specified.

[Chemical composition]
As a chemical component, the copper alloy contains 3% to 15% of Ag. When 3% or more of Ag is contained, it is crystallized as a second phase in the Cu matrix and constitutes a so-called “double phase alloy”. When the Ag content is less than 3%, the effect of composite strengthening by the second phase is small. Even if the Ag content exceeds 15%, the properties (especially strength) of the alloy hardly increase, the effect is saturated, and the conductivity decreases.
The content of inevitable impurities in the copper alloy is preferably the same as oxygen-free copper specified in JIS. For example, it can be made equivalent to the content of impurities in oxygen-free copper C1011 standardized to JIS H2123.
Examples of these impurities include Gd, Y, Yb, Nd, In, Pd, and Te.

[Second phase]
In the second phase, the element is crystallized at the time of casting from a molten alloy containing Cu and the chemical component, and a large amount of Ag is distributed to the second phase during the crystallization. Usually, the Ag concentration in the second phase is 50% or more. The second phase is crystallized, for example, in a needle shape in the Cu matrix, but the crystallization form is not limited to this. The second phase can be observed as a composition different from the parent phase by a BSE (backscattered electron) image of an SEM (scanning electron microscope) after polishing the cross section of the rolled structure after the final step. If the structure is difficult to observe, etching or electropolishing may be performed.

  FIG. 1 schematically shows the rolled material structure of the alloy of the present invention. In this figure, in the rolled material structure, the second phase 4 is dispersed in the matrix of the Cu matrix 2. Then, “the width direction of the plate is defined as“ a perpendicular direction T of rolling ”and the longitudinal direction of the plate is defined as“ the parallel direction L of rolling ”. In the present invention, the second phase preferably has a length in the rolling parallel direction of 10 times or more of the thickness t, and shows, for example, a ribbon shape (tongue piece shape).

[Thickness of the second phase]
In FIG. 1, when viewed from a cross section perpendicular to rolling, the thickness of the second phase (corresponding to the second phase length in the rolling direction) is t1, and the interval between adjacent second phases (distance in the rolling direction) is d. The rolling perpendicular section refers to a section when the rolled material is cut along a plane perpendicular to the rolling surface along the rolling perpendicular direction T. The rolling parallel direction may be determined, for example, as the rolling parallel direction of the rolls formed on the rolling surface.
The strength increases as the thickness t1 of the second phase decreases. Moreover, d can be reduced by increasing the rolling degree. In the case of the alloy of the present invention, higher strength can be obtained by setting t1 to 1 μm or less.

  The reason why the strength is improved by reducing t1 will be further described. A multiphase alloy is a strengthening mechanism that uses a composite law. In general, the strength (σ: stress) of a material depends on the volume fractions of the first and second phases (V1 and V2 respectively). (Σ = V1σ1 + V2σ2), rather than the volume fraction of the second phase, the distance between the dispersed second phases contributes more to the strength. That is, when the interval between the second phases is reduced by processing, that is, the area of the heterophase interface between the Cu matrix and the second phase is increased, that is, the thickness of the Cu matrix is thinned, the highest strength is obtained.

  And in order to narrow the space | interval of 2nd phases, it is necessary for each 2nd phase to become fine and the thickness to also become small. In other words, in order to strengthen the multiphase alloy, it is important to make the initial crystallized product of the second phase fine and further deform the second phase by subsequent processing to reduce the thickness and bring them close to each other. .

[Interval between adjacent second phases]
Further, as described above, as viewed from the cross-section perpendicular to the rolling, as the distance d between the adjacent second phases is smaller, the higher strength is obtained, so d is preferably 3 μm or less. For the same reason that the thickness t1 decreases, the strength depends on the interfacial area. That is, when a line is drawn perpendicularly to the stacking direction of the second phase on the structure photograph (the direction of rolling reduction), the number of interfaces between the parent phase and the second phase (ribbon-like structure) passing through this line Strength depends. And the intensity | strength which only the 2nd phase is sheared when processing shows the intensity | strength of this material, and it is thought that intensity | strength becomes high, so that there are many said interfaces.

[Method for controlling t1 and d]
As a method for controlling t to 1 μm or less, for example, heat treatment is performed at a low workability so that the workability of cold rolling is 90% or more. For example, in the examples described later, heat treatment at 500 ° C. is performed after 30% cold working, and then 99.7% cold rolling is performed.
Moreover, t1 can also be controlled by adjusting the cooling rate at the time of melting and casting so as to refine the crystallized material that becomes the second phase. For example, it is desirable to adjust the amount of heat generated during solidification to exceed the heat capacity of the mold, and preferably the larger the heat capacity of the mold. Also, the faster the mold cooling rate, the finer the crystallized material, and it becomes easier to obtain the same fine structure by melt casting that has been obtained only by strong processing. Therefore, t1 and d can be controlled by combining subsequent processing and heat treatment.
By controlling as described above, the length of the second phase in the rolling parallel direction can be made 10 times or more the thickness t.

[Precipitate]
The copper alloy is formed by further depositing one or more precipitates selected from the group of Fe, Cr and Fe-P in the Cu matrix. The elements constituting the precipitates are contained in the copper alloy material, and this material is subjected to an aging heat treatment after cold working, thereby precipitating mainly in the Cu matrix and precipitation hardening of the copper alloy. Among the precipitates, Fe—P is an intermetallic compound, and the composition ratio is not limited, but is usually a composition ratio of Fe: P = 2: 1.
The total concentration of the elements constituting the precipitate (precipitated elements) in the alloy is 0.1% or more and less than 2%. Although the above precipitates are mainly precipitated in the Cu matrix, some of them are dissolved in the alloy without being precipitated, and thus are defined by the concentration in the alloy. The concentration of the precipitated element in the alloy can be measured, for example, by a wet method.

As already described, as a method for improving the semi-softening characteristics, dislocation pinning by precipitates and increase in recrystallization temperature by additive elements are effective. Further, as a method for improving the stress relaxation characteristics, precipitates are effective for suppressing the grain boundary (interface) slip of the crystal grains. In the multiphase alloy of the present invention, the one corresponding to the grain boundary is the interface between the parent phase and the second phase, and therefore the slip at this interface can be suppressed by the precipitate. Accordingly, the precipitates can improve both the semi-softening characteristic and the stress relaxation characteristic.
Furthermore, when the additive element (Sn etc.) mentioned later is included, heat resistance (semi-softening temperature) improves further.
When the concentration of the precipitated element is less than 0.1%, the precipitate does not sufficiently precipitate, and when it is 2% or more, the particle size of the precipitate exceeds 100 nm and becomes coarse, resulting in the following problems.

The particle size of the precipitate needs to be 20-100 nm. Precipitates mainly precipitate in the Cu matrix and hinder the extension of the second phase by rolling, so when the grain size of the precipitate is coarsened to the thickness of the second phase, the precipitate divides the second phase. The second phase is not stretched and the bending workability is deteriorated. In particular, in the present invention, since the second phase is refined so that the thickness t1 is 1 μm or less, the particle size of the precipitates needs to be 100 nm or less, which is one digit smaller than that. However, if the particle size of the precipitate is less than 20 nm, the precipitate is re-dissolved in the matrix by subsequent processing or the like, so the range is 20 to 100 nm.
The grain size of the precipitate is obtained, for example, by cutting the alloy strip before the final cold rolling in a direction perpendicular to the thickness parallel to the rolling direction, and observing about 10 fields of view with a scanning electron microscope or a transmission electron microscope. be able to. When the size of the precipitate is 5 to 50 nm, it is preferable to shoot at a magnification of 500,000 to 700,000 times, and when it is 100 to 2000 nm, the image is taken at 5 to 100,000 times. Then, the major axis a, the minor axis b, and the area of each of the precipitates having a size of 5 nm or more are measured for each of the photographed photographs using an image analysis apparatus (for example, product name Luzex, manufactured by Nireco Corporation). From these average values, the particle size of the precipitate can be calculated.

  The aging heat treatment can be performed, for example, at a temperature of 300 ° C. to 600 ° C. for 0.5 to 100 hours, whereby the precipitate can be refined. In addition, it is desirable to perform this heat treatment after cold working because diffusion of a solid solution precipitated element is promoted and precipitation is facilitated. In addition, if the heat treatment is performed at a time when the degree of work is large, it is difficult to improve the strength even if it is subsequently cold worked. Therefore, heat treatment at a degree of work as low as possible is desirable. On the other hand, when heat treatment is performed before processing, the precipitated elements that are dissolved are difficult to precipitate. However, if heat treatment is performed for a long time of about 15 hours, fine precipitation occurs and the effect of precipitation strengthening can be obtained. May be.

  As described above, a copper alloy having a 0.2% proof stress of 800 MPa or more can be obtained by setting the thickness t1 of the second phase to 1 μm or less and precipitating fine precipitates in the parent phase.

The content ratio of the precipitate in the alloy can be determined, for example, by analyzing the surface or cross section of the obtained material by Auger Electron Spectroscopy (AES) and performing elemental determination. In this case, a calibration curve may be created in advance for the pure substance of each element, and quantification may be performed.
In addition, even in the same specimen, the content ratio of precipitates varies. Therefore, for example, in one alloy sample, the content ratio of precipitates can be measured with respect to 50 points (50 crystallization products), and the maximum value can be set as the content ratio of precipitates. Moreover, when it contains 2 or more types of deposits, let those total amount be a content rate.

[Additive elements]
Furthermore, it is preferable that the alloy of the present invention contains one or more additive elements selected from the group of Sn, Mg and Ti in a total amount of 0.01% to 0.2%. The additive element mainly dissolves in the Cu matrix, strengthens the copper alloy, and raises the recrystallization temperature of the copper alloy, thereby improving the heat resistance (semi-softening temperature).
When the total amount of additive elements is less than 0.01%, solid solution strengthening is not sufficient, and when it exceeds 0.2%, the electrical conductivity is lowered and the bending workability is also deteriorated.
The method for measuring the content ratio of the additive element in the alloy can be the same as the method for measuring the content ratio of the precipitated element described above.

[Manufacturing]
An ingot is prepared by melting a composition in which electrolytic copper or oxygen-free copper is used as a main raw material and adding the above chemical components and the like in a melting furnace. A rolled material can be obtained by sequentially performing, for example, homogenization annealing, hot rolling, cold rolling, annealing, cold rolling, and annealing on the ingot. Cold rolling is preferably performed, for example, at a working degree η = 3.5 or more.

In addition, this invention is not limited to the said embodiment.
The copper alloy of the present invention can be in various forms such as spring materials (strips) and foils. For example, when the copper alloy of the present invention is used for the spring material, it can be applied to electronic devices such as connectors. The connector can be applied to all known forms and structures, but usually consists of a male (jack, plug) and a female (socket, receptacle). For example, the terminals may be arranged like a spring, with a number of skewered pins arranged side by side and appropriately bent so that the terminals come into electrical contact with each other when fitted to other connectors. And the terminal of a connector is normally comprised with the said copper alloy for electronic devices.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these.

1. Preparation of sample Ingot was cast by adding elements of the composition shown in Tables 1 and 2 to electrolytic copper, and melted in vacuum, and this was homogenized and annealed at a temperature of 800 ° C for 3 hours. After the solution treatment, hot rolling was performed. Further, chamfering was performed and cold rolling was performed. In order to divide the stretched second phase, annealing was performed at 500 ° C., finish cold rolling was performed, and a spring material sample having a plate thickness of 0.1 mm was produced. An aging treatment (15 hours at 500 ° C.) was applied during cold rolling. The total rolling degree of cold rolling is 99.7%, the degree of working per pass is 30 to 36%, and the tension is 350MPa or more (however, the initial pass of cold rolling is 150MPa, and the latter pass when the plate thickness is reduced is about 375MPa) ).
The form of the second phase (thickness t1, d) was determined from the BSE image of the cross section SEM of the sample. The grain size of the precipitate was determined by cutting the alloy strip before the final cold rolling parallel to the rolling direction at a right angle to the thickness, and observing the precipitate in the cross section with 10 fields of view using a scanning electron microscope or a transmission electron microscope. When the size of the precipitate was 5 to 50 nm, the image was taken at a magnification of 500,000 to 700,000 times, and when it was 100 to 2000 nm, the image was taken at 5 to 100,000 times. And using the image analysis apparatus (product name Luzex, manufactured by Nireco Co., Ltd.), the major axis a, the minor axis b, and the area are individually measured for all the precipitates having a size of 5 nm or more. From the average value, the particle size of the precipitate was calculated.

<Sample evaluation>
(1) Strength evaluation
According to JIS-Z2241, the tensile strength of the sample was measured to obtain 0.2% yield strength (YS). The sample was produced according to JIS.
(2) Evaluation of conductivity The conductivity of the sample was determined by the four probe method. The unit% IACS (international annealed copper standard) is the ratio of electrical conductivity to annealed standard soft copper. However, the conductivity decreases when the alloy contains the above additive elements (Sn, etc.). Therefore, if the additive element is not included, the conductivity is 50% IACS or more. If the additive element is contained, the conductivity is 45% IACS or more. Was evaluated as being good.

(3) Evaluation of bending workability A W bending test was performed according to the Japan Copper and Brass Association Technical Standard (JBMA T307). The minimum bending radius (MBR) was determined for a 10 mm wide sample (t: sample thickness) extending in the direction perpendicular to the rolling. The samples of each experimental example and comparative example were evaluated according to the following criteria.
○: MBR / t value is smaller than the reference example value Δ: MBR / t value is larger than the reference example value ×: MBR / t value is considerably larger than the reference example value MBR of the reference example / T is about 1.
(4) Stress relaxation rate As a stress relaxation property at high temperature, a stress relaxation rate (Technical Standard of Japan Copper and Brass Association (JCBA): JCBA T309) was measured. In this test, a strip test piece having a width of 10 mm is attached to a cantilever beam, the deflection displacement (displacement at a predetermined position at the free end) after being held for a predetermined time in a high temperature bent state is compared with the initial state, and the sag due to temperature It is a method to evaluate. When the deflection after the test and the initial state does not change, the value of the stress relaxation rate is 0%, and as the deflection after the test becomes larger than the initial state, the value of the stress relaxation rate increases (stress decreases).
The stress relaxation rate is the following formula: Stress relaxation rate = (y−y1) / y0 × 100 (%)
(However, y = deflection displacement (mm) after elapse of a predetermined time, y1 = initial deflection (mm), y0 = set height (mm)).
The set height is the following formula: y0 = (2/3) × l × l × σ0 / (E × t)
(Where, l = target distance (mm), σ 0 = load stress (kg / mm 2); 80% of 0.2% proof stress or any stress below 0.2% proof stress, E = Young's modulus (kg / mm 2 ), T = plate thickness (mm)).

The stress relaxation was measured until the sample was 150 ° C. and showed a certain relaxation rate. Specifically, the stress relaxation rate was measured for 25, 50, 100, and 200 hours, and a substantially constant stress relaxation rate was shown in about 1000 hours. This value was taken as the stress relaxation rate.
In addition, the stress relaxation rate after 150 degreeC x 1000 hours of the phosphor bronze generally used is about 40%. Therefore, in the evaluation of the following examples and comparative examples, those having a stress relaxation rate of 40% or less were regarded as having good heat resistance.

The obtained results are shown in Tables 1 to 9.
Tables 1 to 5 show the results of the examples, and Tables 6 to 9 show the results of the comparative examples. Here, in the comparative example of Table 6, the total processing degree, the solution treatment temperature, and the heat treatment temperature were set to the same conditions as in the examples. On the other hand, in the comparative example of Table 7, the solution treatment temperature and the heat treatment temperature were the same as those in the example, but the total degree of processing was reduced to 70.0%.
In the comparative example of Table 8, the total degree of processing and the solution treatment temperature were the same as those in the example, but the heat treatment temperature was reduced to 200 ° C. However, in Comparative Examples 57 to 59 among the comparative examples in Table 8, the heat treatment temperature was reduced to 200 ° C and the solution treatment temperature was reduced to 750 ° C.
In the comparative example of Table 9, the total processing degree and the solution treatment temperature were the same as those in the example, but the heat treatment temperature was increased to 700 ° C. However, among Comparative Examples 82 to 84 among Comparative Examples in Table 9, the heat treatment temperature was increased to 700 ° C and the solution treatment temperature was reduced to 750 ° C.

  As is apparent from Tables 1 to 5, in each example, the 0.2% proof stress was improved to 800 MPa, the bending workability was excellent, and the electrical conductivity was also good. Further, in each example, the stress relaxation rate was 40% or less, and the heat resistance was excellent.

On the other hand, in Comparative Examples 1 to 3 in which no precipitation element was added in Table 6, no precipitate was deposited, the stress relaxation rate exceeded 40%, and the heat resistance was poor. In the case of Comparative Example 4 in which the Ag content was less than 3%, the second phase did not crystallize, and the 0.2% yield strength decreased to less than 800 MPa. In the case of Comparative Example 5 in which the Ag content exceeded 15%, the bending workability deteriorated.
In Comparative Examples 6, 7, 9, and 10 in which the total content of the precipitated elements was 2% or more, the particle size of the precipitate exceeded 100 nm, and the bending workability deteriorated. In these comparative examples, since the heat treatment temperature was high, the size of the precipitate changed.
In the case of Comparative Example 8, the particle size of the precipitate exceeded 100 nm and became coarse, and the bending workability deteriorated.
In Comparative Examples 11 and 12 in which the total content of the precipitated elements was less than 0.1%, no precipitate was deposited, the stress relaxation rate exceeded 40%, and the heat resistance was poor.
In the case of Comparative Examples 13 to 16 in which the total content of additive elements exceeded 0.5%, the conductivity decreased and the bending workability also deteriorated.

  In the case of each comparative example shown in Table 7, since the total workability was reduced to 70.0%, the thickness t1 of the second phase exceeded 1 μm, and the 0.2% proof stress decreased to less than 800 MPa.

  In the case of each comparative example shown in Table 8, since the heat treatment temperature was reduced to 200 ° C., the precipitate did not precipitate or the precipitate did not grow sufficiently and the particle size was less than 20 nm, so the bending workability was lowered. did.

  In the case of each comparative example shown in Table 9, since the heat treatment temperature was increased to 700 ° C., the thickness t1 of the second phase exceeded 1 μm, and the 0.2% proof stress decreased to less than 800 MPa.

It is the figure which showed typically the rolling material structure | tissue of the alloy of this invention.

Explanation of symbols

2 Cu base material 4 Second phase

Claims (3)

  Containing at least 3% and not more than 15% of Ag by mass%, one or more precipitates selected from the group of Fe, Cr and Fe-P are precipitated in the Cu matrix and constitute the precipitates The total concentration in the alloy of the elements to be made is 0.1% or more and less than 2%, consisting of the balance Cu and unavoidable impurities, and a 0.2% proof stress consisting of a Cu parent phase and a second phase having a yield strength of 800 MPa or more, A high-strength, high-conductivity, two-phase copper alloy excellent in bending workability in which the grain size of the precipitate is 20-100 nm and the thickness of the second phase is 1 μm or less when viewed from a cross section perpendicular to rolling.   2. The high-strength, high-conductivity, two-phase copper alloy according to claim 1, wherein when viewed from a cross-section perpendicular to rolling, an interval between adjacent second phases is 3 μm or less.   Furthermore, the high intensity | strength highly conductive two-phase copper alloy of Claim 1 or 2 which contains 0.01 to 0.2% in total of 1 or more types of additional elements chosen from the group of Sn, Mg, and Ti.

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