JP4404786B2 - High strength and high conductivity copper alloy and method for producing the same - Google Patents

Description

  The present invention relates to a high-strength and highly conductive copper alloy and a method for producing the same.

Spring materials for electrical and electronic equipment such as terminals, connectors, switches, and relays are required to have excellent spring characteristics, bending workability, and electrical conductivity. Conventionally, phosphor bronze has been used. High-strength, high-conductivity alloys have been developed due to the demand for further miniaturization.
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 to increase the electrical conductivity has a relationship of decreasing the strength. Therefore, an alloy system (double phase alloy) in which the second phase is crystallized in the Cu matrix has been developed. In this alloy, the second phase is dispersed in a fiber shape by strong processing and has a strength equal to or higher than that of phosphor bronze, and the parent phase is Cu. Therefore, the conductivity is 60% IACS (internationally annealed copper standard: High conductivity exceeding the ratio of electrical conductivity to annealed standard annealed copper is 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 8).

  In the case of the above prior art, means such as drawing and rolling are used as a processing method for drawing the second phase into a fiber shape. For example, in Patent Documents 1 and 2 described above, when a multiphase alloy is rolled and manufactured, the second phase is sufficiently stretched in the rolling direction to become fibrous, and the rolling proceeds in the direction perpendicular to the rolling direction (the longitudinal direction of the rolled material). It also describes that the strength of the rolled material is also improved.

In addition, rolling is a processing method capable of continuously producing various plate materials and the like, but there is a problem that the degree of processing cannot be increased so much due to restrictions on material dimensions before and after processing. That is, the processing degree is expressed by true strain η = ln (A ₀ / A) (A ₀ : cross-sectional area before processing, A: cross-sectional area after processing), but the plate thickness decreases as the processing degree increases. Therefore, when the product thickness is reached, further processing becomes impossible. For example, the degree of work of a normal rolled material is only about η = 1 to 6 (63.2% to 99.8%), and a material having a very large size is required to obtain a larger η, The strength of the multiphase alloy cannot be improved.
For this reason, repeated roll-bonding rolling (hereinafter referred to as “ARB” as appropriate) has been proposed (see, for example, Patent Document 9). This technique is a method of performing strong processing by rolling without reducing the final plate thickness by repeating the cycle of re-rolling after laminating the material after rolling to the original plate thickness after cutting. .

JP-A-6-192801 JP-A-6-279894 JP-A-9-104935 JP-A-9-235633 Japanese Patent Laid-Open No. 9-249925 JP-A-10-53824 Japanese Patent Laid-Open No. 10-140267 Japanese Patent Publication No. 48-34652 Japanese Patent No. 2961263

In general, a multiphase alloy is an alloy that is strengthened by using a composite rule, or an alloy that is strengthened by increasing the interphase interface area, and is strengthened by dispersing the second phase in a fibrous form (fiber form). . Here, it is made by dispersing the crystallized second phase that does not dissolve in copper into a fibrous form by strong processing in the copper matrix phase, and the effect by increasing the interphase interface area is great. For this reason, the strength of the second phase increases as the number of the second phase is more dispersed (finely dispersed if the volume fraction is the same), the second phase is more easily stretched, and the degree of processing is increased.
The above-described conventional multiphase alloys are all two-phase alloys, and include Cu-bcc alloys such as Cu-Fe alloys, Cu-Cr alloys, Cu-Nb alloys, and Cu-Ag alloys (eutectic alloys). ). However, although Cu-Ag alloy tends to make initial crystallized fine, it is inferior in hot workability and heat resistance, and has a high material cost. On the other hand, compared with Cu-Ag alloy, Cu-bcc alloy is excellent in heat resistance and material cost is low. However, when the Fe content is increased in order to improve the strength, productivity is lowered due to a decrease in conductivity, an increase in melting point, a solidification defect due to a large solid-liquid coexistence region, and the like.
In particular, in the case of a Cu—Fe alloy, since the primary crystal is the Fe phase and it is difficult to refine the crystallized product depending on the casting conditions, there is a limit to increasing the strength by miniaturizing the Fe crystallized product. Therefore, increasing the amount of Fe added (the proportion of the Fe phase) to improve the strength not only reduces the conductivity, but also does not increase the number of crystallized substances in the second phase. It becomes coarse and the increase in strength is small. In addition, the productivity described above is reduced.
That is, 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 and highly-conductive copper alloy excellent in both strength and conductivity and a method for producing the same.

  As a result of various studies, the present inventors have crystallized an Fe phase and an Ag phase in a Cu matrix to form a three-phase alloy, thereby preventing a decrease in conductivity due to excessive addition of Fe, It has been found that the strength can be improved without losing electrical conductivity by miniaturization and coexistence of the Ag phase.

  In order to achieve the above object, the high-strength, high-conductivity copper alloy of the present invention contains 7% to 25% Fe by mass, 3% to 10% Ag, and the balance Cu and unavoidable It is characterized by comprising Cu impurities, a Cu parent phase, an Fe phase containing 70% or more of Fe, and an Ag phase containing 50% or more of Ag.

The high-strength and high-conductivity copper alloy preferably further contains 0.05% or more and 1% or less in total of one or more trace elements selected from the group of Sn, Mg and Zr by mass%. .
In the rolling surface direction, the average thickness d of the Cu matrix phase separated by the adjacent phases of the Fe phase and the Ag phase satisfies the relationship of d ≦ 400 nm. It is preferable that the average aspect ratio At ₂ satisfies the relationship of 10 ≦ At ₂ .

Here, the aspect ratio of the Fe phase is defined by (elongation width of Fe phase) / (thickness of Fe phase in the rolling thickness direction). Therefore, the aspect ratio At viewed from the cross section along the direction perpendicular to the rolling (the cross section perpendicular to the rolling) is represented by t2 / t1 in FIG. t2 and t1 can be obtained from a cross-sectional image of the Fe phase. For the t2 and t1 in the Fe phase, the maximum values of t2 and t1 may normally be adopted from the BSE (reflected electron) image of the SEM (scanning electron microscope) obtained for the cross section perpendicular to the rolling.
The At is calculated from one t2 of Fe phase, t1 measured for Fe phase plurality (e.g., 100), the average value of the obtained At may be set to the average aspect ratio At _2.

One form of the manufacturing method of the high-strength, high-conductivity copper alloy of the present invention is a manufacturing method of the high-strength, high-conductivity copper alloy, which contains Fe in an amount of 7% to 25% by mass, and contains 3 Ag. Two rolling materials of copper alloy containing not less than 10% and not more than 10%, the balance being Cu and unavoidable impurities, co-existing with Cu parent phase, Fe phase containing 70% or more of Fe, and Ag phase containing 50% or more of Ag The first step of laminating as described above and the second step of rolling the laminated rolling materials in the laminating direction are repeated one or more times in this order. In addition, the rolling raw material in the case of laminating two or more sheets may be the same type or different types.
The rolled material preferably further contains 0.05% or more and 1% or less in total of one or more trace elements selected from the group consisting of Sn, Mg, and Zr by mass%.

  According to the present invention, a high-strength, high-conductivity copper alloy excellent in both strength and conductivity can be obtained.

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

<Composition of high strength and high conductivity copper alloy>
[Chemical composition]
The said copper alloy contains 7% or more and 25% or less of Fe by mass%, contains 3% or more and 10% or less of Ag, and consists of the remainder Cu and inevitable impurities. When Fe is contained in an amount of 7% or more, it is crystallized as an Fe phase in the Cu matrix, and when Ag is contained in an amount of 3% or more, it is crystallized as an Ag phase in the Cu matrix to form a three-phase “multiphase alloy”. . Preferably, the copper alloy contains 7% to 25% of Fe. The Fe phase mainly contributes to strengthening with an increase in the interphase interface area as a multiphase alloy. In addition, the Ag phase is considered to contribute mainly to solid solution strengthening, precipitation strengthening, refinement of the initial crystallized product of the Fe phase, and strengthening accompanying an increase in the interphase interface area as a multiphase alloy. In addition, even if the Ag content is less than 3%, it contributes to solid solution strengthening and precipitation strengthening of the Cu mother phase. However, by causing the Ag phase to crystallize with a content of 3% or more, the interfacial area is further reduced. The effect of strengthening with the increase is obtained. In the Cu-Ag alloy, Ag dissolves up to 8%. However, since casting is performed in a non-equilibrium state, crystallization occurs even when Ag is 3%.

  If the Fe content is less than 7%, the effect of composite strengthening by the Fe phase is small, and if it exceeds 25%, casting and the like become difficult and the productivity is lowered, or the conductivity of the obtained alloy is lowered. Or If the Ag content is less than 3%, the effect of composite strengthening by the Ag phase is small, and if it exceeds 10%, the cost increases. On the other hand, when the Ag content exceeds 10%, productivity such as hot workability is lowered, and heat resistance is lowered.

[Fe phase and Ag phase]
The Fe phase and the Ag phase are obtained by crystallization of Fe or Ag from a molten alloy containing Cu and the above chemical components during casting. The Fe phase contains 70% or more of Fe, and the Ag phase contains 50% or more of Ag. The Fe phase and the Ag phase are crystallized, for example, in a needle shape in the Cu matrix, but the crystallization form is not limited to this. In addition, when the trace element described below is included, the trace element is distributed at a predetermined ratio between the Cu parent phase and the Fe phase (or Ag phase). In addition, although Cu parent phase contains 90% or more of Cu, for example, it is not restricted to this.
The Fe phase and the Ag phase can be observed as a composition different from that of the parent phase by a SEM BSE image after polishing the cross section of the rolled structure after the final process. If the structure is difficult to observe, etching or electropolishing may be performed.

[Three-phase alloy]
Next, the reason for using the three-phase alloy system in the present invention will be described. First, a Cu-Ag alloy which is a two-phase alloy is inferior in hot workability and heat resistance, and has a high material cost. On the other hand, Cu—Fe alloy has lower strength than Cu—Ag alloy, and if the Fe content is increased in order to improve strength, productivity increases due to higher melting point and wider solid-liquid coexistence region. descend. Further, the Fe phase is coarsened and the strength cannot be increased enough to meet the increase in the content, and the conductivity is lowered. Therefore, when Ag is contained in the Cu—Fe alloy system, the presence of Ag suppresses the coarsening of the Fe phase. Further, since the melting point does not increase, the deterioration of productivity is prevented. In addition, when Ag is contained, the crystallized product of the Fe phase (Ag phase) is refined, and even when Ag is dissolved in the Cu matrix, the decrease in conductivity is small. Thus, by using a Cu—Fe—Ag alloy, both strength and conductivity can be improved and heat resistance can be improved as compared with a two-phase alloy.

  In addition, as a method for improving the strength of the multi-phase alloy, the initial phase crystallized material other than the Cu matrix is refined, the degree of work (for example, the degree of cold work) is increased, and the different phases are deformed by the work. It is easy to do. However, in the case of a Cu—Fe alloy, the crystallized Fe phase has high rigidity and is difficult to be deformed by processing, but by using a Cu—Fe—Ag alloy, the Fe phase is easily deformed. This is considered to be due to the interaction between the Fe phase and the Ag phase.

[Inevitable impurities]
The content of inevitable impurities in the copper alloy does not need to be as clean as oxygen-free copper C1011 standardized in JIS H2123. For example, it is acceptable if the impurity content is within the range normally mixed from furnace materials or raw materials. Is done.

[Trace elements]
The copper alloy preferably further contains one or more trace elements selected from the group consisting of Sn, Mg and Zr by mass% as a trace element in a total amount of 0.05% or more and 1% or less. The trace element causes precipitation strengthening (or solid solution strengthening) of the copper alloy, improves heat resistance, or refines initial crystals of the Fe phase and / or Ag phase during the casting of the copper alloy, Improve strength. If the content of the trace element is less than 0.05%, these effects may not be observed, and if it exceeds 1%, the conductivity of the alloy may be significantly reduced.
Sn and Mg contribute to solid solution strengthening, Zr and Mg contribute to precipitation strengthening and heat resistance improvement, and Sn also improves strength by refinement of initial crystals of Fe phase and / or Ag phase. Contribute.

<Rolling high-strength, high-conductivity copper alloy>
By rolling the alloy material (such as an ingot), the strength of the alloy can be further improved. In general, a multi-phase alloy is an alloy that is strengthened by dispersing a phase different from the matrix, such as a fiber or ribbon, in the matrix, and crystallized without being dissolved in Cu by strong processing. The Fe phase and the Ag phase are stretched and dispersed in the Cu matrix to obtain high strength. Strong processing includes drawing, rolling, and the like, but when rolled, wide materials and plate materials can be produced.
In addition, by setting it as a Cu-Fe-Ag alloy, it becomes easy to deform | transform compared with the case where Fe phase and Ag phase exist independently in a two-phase alloy. Therefore, the elongation of each phase when cold rolling is performed is larger than that of the two-phase alloy, and the strength is further increased.

<Average thickness d of Cu matrix>
By the way, the strength of the multiphase alloy of the present invention has an elastic effect and a plastic effect, and the elastic effect is strengthened by the presence of a phase harder than the parent phase. According to the composite side, the formula σ = V ₁ σ ₁ + V ₂ σ ₂ + V ₃ σ ₃
(Subscripts 1, 2, and 3 indicate Cu, Fe, and Ag, respectively, V indicates a volume fraction, and σ indicates stress). However, in the case of the alloy of the present invention, V ₁ is much larger than V ₂ and V _3. For example, when V ₁ = 0.8 and V ₂ = 0.1, the stress σ _{2 of the} Fe phase is up to 100 MPa. Even if it is increased, the strength of the alloy as a whole increases only by 10 MPa.
On the other hand, the plastic effect is an effect caused by deformation only in the Cu matrix, and the strength is increased when the interphase interface area between the Cu matrix, the Fe phase, and the Ag phase increases.
From the above, by increasing the strength (stress) σ and the volume fraction V of the Fe phase and the Ag phase, the heterogeneous interface area (the interface between the Cu matrix and the Fe phase, and the interface between the Cu matrix and the Ag phase) Increasing the amount of (dislocation failure) is more important in terms of increasing the strength.
In other words, the factors that are effective in strengthening the multiphase alloy are as follows: 1) a large volume fraction, 2) a large interfacial area, and 3) the thickness of the parent phase (the mother sandwiched between the second and third phases). The thickness of the phase is small. Among these, when 1) becomes large, the thickness of the parent phase also becomes thin and the effect of 3) can be obtained, but it is not efficient to express this effect. Therefore, in the present invention, attention is paid to the above 2) and 3). Here, when 2) is increased, the structure becomes finer and the thickness of the parent phase also becomes thinner. Further, in order to make 3) thinner, the degree of processing is increased, but as a result, the heterogeneous interface area also increases. That is, 2) and 3) are related to each other, and it is considered that the effects 1) to 3) are synergistically effective in strengthening the multiphase alloy.
However, it is actually difficult to measure the interfacial area as an index indicating the degree of 2) and 3). Therefore, the average thickness (or the interval between adjacent second and / or third phases) d of the Cu matrix is used as a parameter for the interphase interface area. This will be described with reference to FIG.

First, when a rolled material is considered as the alloy of the present invention, the structure shown in FIG. 1 is exemplified as the rolled material structure. In this figure, the Fe phase and the Ag phase 4 are dispersed in the Cu matrix (matrix) of the rolled material 2 (the Fe phase and the Ag phase are not particularly distinguished in FIG. 1). The sheet width direction is defined as “rolling perpendicular direction T”, and the longitudinal direction of the sheet is defined as “rolling direction L”. In the case of a conventional multiphase alloy, the second phase is hardly drawn in the direction perpendicular to the rolling and is in the form of a fiber. On the other hand, in the present invention, the Fe phase and the Ag phase are also stretched in the direction perpendicular to the rolling direction, and show, for example, a ribbon shape (tongue piece shape).
As described above, in the case of a rolled material, the ribbon-like Fe phase and Ag phase are dispersed in a state of being laminated in the rolling surface direction, and the thickness of the Fe phase and Ag phase is thin. The thickness of the Cu parent phase delimited by the Fe phase or the Ag phase as viewed from the direction is smaller, and the number of Fe phases and Ag phases in the unit volume of the alloy is increased, that is, the interfacial area is increased. become.

Now, if the thickness of the Fe phase and the Ag phase is ignored, the larger the number of Fe phases and Ag phases crossing the line parallel to the rolling surface direction, the narrower the interval between the phases,
The average thickness d of Cu parent phase is expressed by d = (length of line segment m) / (number of Fe phase and Ag phase crossing line segment m). In addition, as length of the line segment m, it is good also as the plate | board thickness of a rolling material, and good also about the visual field area | region of a microscope, for example. Further, d obtained for a plurality of line segments may be further averaged. When a coarse Fe phase exists, the distance is subtracted from the length of the line segment. Specifically, d is obtained by subtracting the sum of the distances of Fe phases of 50 nm or more from the length of the line segment, and dividing it by the number of Fe phases and Ag phases crossing it. The coarse Fe phase is, for example, as shown in FIG.
The above d is sufficiently smaller than the thickness (plate thickness) of the alloy material and is usually sufficiently larger than the thicknesses of the Fe phase and the Ag phase. Compared to the length of the line segment, the Ag phase is negligibly small.

  From the viewpoint of improving the strength of the alloy by increasing the heterogeneous interface area, it is preferable that d satisfies the relationship of d ≦ 400 nm. When a three-phase alloy is used, the initial crystallized material becomes finer and the number thereof increases as compared with the two-phase alloy, so that the interphase interface area increases. Further, by using a three-phase alloy, the Fe phase and the Ag phase are easily deformed as compared with the two-phase alloy, and d is likely to be small.

<Average aspect ratio At ₂ of Fe phase>
When the rolled material of the present invention is viewed from a cross section perpendicular to the rolling, the average aspect ratio At ₂ of the Fe phase is set to 10 or more. A method for defining the average aspect ratio At ₂ will be described with reference to FIG.
As described above, in the present invention, the Fe phase and the Ag phase are also stretched in the direction perpendicular to the rolling direction, and show, for example, a ribbon shape (tongue piece shape). In addition, in other conventionally known multi-phase alloys, even if there is a case where there is a ribbon-like (tongue piece-like) shape in which the second phase is stretched also in the direction perpendicular to the rolling direction, in the present invention, Preferably, the length in the direction perpendicular to the rolling direction of the second phase is longer than that of the conventional double phase alloy, and the average aspect ratio is also larger in the present invention.

[Regulation of At]
In the present invention, At ₂ is 10 or more. When At ₂ is less than 10, the Fe phase is not stretched in the direction perpendicular to the rolling direction, the strength in this direction is insufficient and the strength is not improved, and cracking occurs at the interface between the different phases. Decreases. On the other hand, At ₂ does not have an upper limit, but if At ₂ is 110 or less, production is easy. In addition, in a normal rolling method, it may be difficult to obtain At ₂ exceeding 80, but in ARB (repeated lap bonding rolling) described later, it is easy.
The average aspect ratio At ₃ of the Ag phase can also be defined in exactly the same way as the above At _2. However, since the Ag phase is more easily deformed than the Fe phase, At ₃ > At ₂ . Therefore, it is sufficient to define the lower limit of At _2.

[Method for adjusting At ₂ ]
Usually, when rolling is performed, the structure is stretched in the rolling direction, but not so much in the direction perpendicular to the rolling direction. Therefore, in consideration of the finally managed value of At, there is a method of growing a crystallized product (Fe phase) to a certain size before rolling so that the width t2 of the Fe phase extends in the direction perpendicular to the rolling. . In addition, At is increased by performing width setting by hot forging or cold forging. In addition, by lowering the rolling direction tension during rolling, the structure in the rolling direction can be weakened to extend the Fe phase in the direction perpendicular to the rolling direction, the degree of processing per pass can be reduced, and the number of passes can be increased. The Fe phase can be stretched in the direction perpendicular to the rolling.

  For example, first, hot forging is performed to widen the width to about 1.4 times the ingot width. Thereafter, hot rolling and cold rolling are performed, and heat treatment, cold rolling, and heat treatment are performed again.

  Next, cold rolling is performed after the heat treatment. To increase At, the work degree η = 0.16 to 0.36 (15% to 30%) per pass during cold rolling, preferably η = The tension applied during cold rolling should be as low as 0.29 (25%) or less, and should be suppressed to 80 MPa to 300 MPa, preferably 200 MPa or less.

<Manufacturing>
Hereafter, an example of the manufacturing method of the alloy of this invention is given. First, electrolytic copper or oxygen-free copper is used as a main raw material, and a composition to which the above chemical components and others are added is melted in a melting furnace to produce an ingot (ingot). After this ingot is homogenized and annealed, it is subjected to hot (warm) rolling or hot (warm) forging or hot (warm) rolling and hot (warm) forging, and cold rolling.
As a rolling method, the final plate thickness may be obtained by the above-described cold rolling, but ARB can also be performed. When performing by ARB, it is preferable to carry out as follows.

<Repeated lap joint rolling (ARB)>
ARB performs the above-described cold rolled material as a rolled material for ARB. FIG. 3 is a process diagram schematically showing an example of an ARB.
In this figure, first, the surfaces S and S of the two rolled materials 1A and 1B are respectively cleaned. As the rolling material, a copper alloy ingot, a material obtained by appropriately homogenizing and annealing the ingot, and then hot rolling or hot forging, or a cold rolled material can be used. The thickness of the rolled material may be a thick material such as an ingot, or a cold rolled material having a thin plate thickness close to the final product thickness. The cleaning is for removing oil, oxide film, and the like on the surface so that the rolled materials are joined by rolling. For example, degreasing, polishing, washing, and the like can be performed. In the ARB, a cleaning process is currently essential, but it can be omitted in the future if the surface roughness of the rolled material can be strictly controlled by annealing, rolling, or the like.
Next, the rolling materials 1A and 1B are stacked (I: first step), and the tip portions J are joined together. Any number of rolled materials may be stacked as long as it is two or more. Joining is not essential, but it is preferably performed to prevent the tip portion from being opened during rolling to prevent joining, or the formation of a gap between the laminated materials to cause surface oxidation or the like. In addition to welding, the joining method may be mechanical joining (fastening with a bolt or the like, binding with a wire or the like). Further, in addition to the front end, the rear end (rolling side) of the rolled material may be joined.
Next, the rolling materials 1A and 1B are passed between the rolls 10 and 10, and rolled in the stacking direction (vertical direction in the figure) (II: second step). Depending on the workability of the rolled material, the rolled material may be heat-treated before rolling or may not be heat-treated.
Next, using the cutter 20, the rolled material 1 </ b> C is cut in, for example, the short direction (the direction perpendicular to the rolling direction) to obtain two rolled materials 1 </ b> D and 1 </ b> E whose longitudinal directions are divided. Each rolled material is subjected to ARB again and rolled in the same manner as the rolled material.
In the present invention, various heat treatments and annealing may be performed before and after rolling, in the middle thereof, and after final rolling.

In ARB, the series of steps described above are repeated one or more times in this order. When repeating twice or more, the process which cut | disconnects a rolling material and returns to the beginning of a process is performed. For example, when the reduction rate of ARB is 50%, the thickness of the rolled material before rolling is t ₀ , but the thickness of the rolled material 1C after rolling is also t ₀ (0.5t ₀ + 0.5t ₀ ). It can be rolled without reducing the actual material thickness. Further, the rolling stock 1A of FIG. 3, when Fe a (Ag) Phase 1x interval (thickness of the Cu matrix) and _{d 0} in 1B, the thickness _d 1 = 0.5d ₀ next to the Cu matrix after rolling (When the reduction ratio is 50%), it can be seen that the structure of the rolled material undergoes strong processing and becomes finer.

As described above, the alloy of the present invention is a Cu-Fe-Ag-based three-phase alloy, whereby the Fe phase is easily deformed, the average thickness d of the Cu matrix is reduced, and the strength is increased. Can do. Considering such a strengthening mechanism, as the degree of work η is increased by rolling with ARB, the distance between the Cu matrix phases decreases and the thickness decreases, and the heterogeneous interface area between the Cu matrix, the Fe phase, and the Ag phase increases. To increase the strength. As the number of repetitions of ARB increases, the degree of processing can be increased. Moreover, although there is no upper limit to the number of repetitions, it may be set within a range in which cracking due to rolling does not occur according to the composition of the alloy. Depending on the necessary final plate thickness, for example, the number of repetitions is about 4 to 5 times. In particular, the final product thickness of the rolled material is determined in advance, and in normal rolling, the rolling degree cannot be increased beyond this thickness. However, according to ARB, after processing to less than the final product thickness, the degree of processing can be increased by repeating rolling with overlapping.
In addition, if the rolling reduction per rolling in ARB is 50%, the thickness of the rolled material after n times of repetition becomes 1/2 ⁿ of the thickness of the rolled material. Therefore, when the number of repetitions is 4 and 5, respectively, the processing degrees are η = 2.77 (93.8%) and 3.47 (96.9%), respectively.

In addition, when heat-treating a rolling raw material before ARB, if the Fe phase and Ag phase (especially Ag phase) of a rolling raw material are hold | maintained at the temperature below the temperature divided by heat, the strength deterioration by division | segmentation of a 2nd phase will be carried out. Since it is prevented and ductility is restored, cracks are unlikely to occur in the ARB, and joining becomes easy.

  Conventionally, rolled materials of copper-based multiphase alloys cannot be used for spring materials such as terminals due to problems such as electrical conductivity. It has been used as a product part. In the present invention, a copper alloy having both good conductivity and strength can be obtained, and it is possible to greatly contribute to the miniaturization, weight reduction and performance improvement of electronic devices, and the like.

  In addition, this invention is not limited to the said embodiment. Moreover, as long as there exists an effect of this invention, the copper alloy in the said embodiment may contain another component.

  The present invention can be applied to electronic devices such as connectors. As for the connector, the terminal is comprised by the manufacturing method of the said high intensity | strength highly conductive copper alloy. The connector can be applied to any known form and structure, and usually consists of a male (plug) and a female (jack). 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.

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

1. Manufacture of a sample The element of the composition shown in Table 1 was added to electrolytic copper and melted in vacuum to cast an ingot, which was subjected to homogenization annealing, hot-rolled, and cold-rolled to obtain a rolling material. The thickness of the rolled material was 0.1 mm, 0.2 mm, 0.4 mm, or 0.8 mm.
1-1. Normal rolling: Examples 1 to 10, Comparative Examples 1 to 8
The rolled material was degreased, polished, and washed during the cold rolling, and then annealed at a temperature lower than the temperature at which the Fe phase and the Ag phase were divided by heat, and cold rolled until the final thickness was reached. For comparison, samples prepared in the same manner by adding elements having the compositions shown in Table 1 were designated as Comparative Examples 1-8.
1-2. ARB: Examples 11-13, Comparative Examples 9-11
The rolled material was degreased, polished, and washed during the cold rolling to clean the surface, and then annealed at a temperature equal to or lower than the temperature at which the Fe phase and Ag phase were separated by heat. Next, rolled materials of the same thickness are stacked, and a total of four corners at the front and rear corners are welded, and ARB is performed with the number of repetitions of 1 or 2 to obtain a final thickness (working degree η is 6 (99 8%))). Samples of Examples 1 to 12 were obtained as described above. For comparison, samples prepared in the same manner by adding elements having the compositions shown in Table 1 were designated as Comparative Examples 9 to 11.
In the following tables, for example, the number before each element symbol of “Cu-15Fe-4Ag” in Example 10 indicates the content (%) of Fe and Ag in the alloy, and the number is 1 or less. Things were trace elements. For example, in the case of Example 10, the trace elements are Mg and Sn.

2. Evaluation of Sample (1) Calculation of Average Aspect Ratio At2 of Fe Phase After polishing the rolled perpendicular section of the sample after rolling to the final plate thickness (1 μm diamond paste, but etching or electropolishing if Fe phase is small and difficult to observe Later), BSE images were obtained using SEM. In the image, the black portion compared with the Cu parent phase was regarded as the Fe phase, and the thickness t1 and the extension width t2 of the Fe phase were determined. t1 and t2 take the maximum value of each Fe phase. Seeking At ₂ from the t1, t2 measured in the image, each seeking At ₂ for 100 Fe phase was adopted as the averaged as the average aspect ratio. Note that the atomic number of Ag and Fe is different from that of Cu, and the backscattering coefficient increases as the atomic number increases. Therefore, the Ag phase appears white and the Fe phase appears black compared to the Cu matrix in the BSE image.

(2) Average thickness d of Cu matrix
The polished sample used for the calculation of At ₂ was observed with a field of view of 8000 times, and the upper and lower sides of the observation field of view were the length of the line segment. Five lines were drawn at equal intervals for the same visual field, and 30 visual fields were observed.
(Length of line segment m) / (Number of Fe and Ag phases crossing line segment m)
Thus, the average thickness d (nm) of the Cu matrix was determined.

(3) Bending workability The sample after rolling to the final plate thickness is subjected to a W bending test in accordance with JIS H3110 and H3130, and the minimum of a 10 mm wide sample (t: sample thickness) extending in the direction perpendicular to the rolling direction and the rolling direction, respectively. The bending radius (MBR) was determined. And bending workability was evaluated according to the following criteria.
○: MBR / t ≦ 2.5 Δ: MBR / t exceeds 2.5 and less than 4 ×: MBR / t ≧ 4

(4) Measurement of strength According to JIS Z2241, the tensile strength of the sample in the rolling direction was measured, and 0.2% yield strength (YS: yield strength) was obtained. The sample was produced according to JIS.
(5) Measurement of conductivity The conductivity of the sample was determined by the four probe method.
(5) Heat resistance About each sample, it annealed at 250 degreeC for 1 hour, and evaluated the heat resistance for the fall of the intensity | strength (0.2% yield strength) after annealing on the following references | standards.
◎: Strength decrease after annealing is less than 15 MPa ○: Strength decrease after annealing is 15 MPa or more and 25 MPa or less △: Strength decrease after annealing exceeds 25 MPa and 50 MPa or less ×: After annealing With a strength drop of more than 50 MPa

  The obtained results are shown in Tables 1 and 2.

As is clear from Table 1, each example was excellent in both strength (0.2% yield strength) and conductivity. Each example was also excellent in heat resistance.
In the case of Example 1, which is a three-phase alloy, the strength is significantly increased as compared with Comparative Examples 2, 3, and 6 that are two-phase alloys. Further, in Example 2 in which the average thickness d of the Cu matrix exceeded 400 nm, the strength was slightly reduced as compared with the other examples, but there was no practical problem. Further, in Example 3 in which the average aspect ratio At ₂ of the Fe phase was less than 10, the bending workability in the direction perpendicular to the rolling was slightly lowered as compared with the other examples, but there was no practical problem.

Here, Example 3 has poor bending workability in the direction perpendicular to rolling (x), but on the other hand, it is strong and has high electrical conductivity, so it is effective for applications that do not require bending workability (for example, fork-type connectors). Can be applied to.
Moreover, although Examples 1-3 are the same compositions, the conditions and frequency | count of an aging treatment at the time of manufacture, and a workability differ. Specifically, the degree of processing increases in order of increasing strength (in the order of Examples 1, 3 and 2) (for each example, η = 4.5 to 6 (98.9% to 99.8%)). Adjust between). In Examples 1 to 3, the aging treatment was performed slightly on the overaging side from the peak aging condition, but the lower the strength, the more on the overaging side.

On the other hand, in the case of Comparative Examples 1 to 5 in which Cu—Fe alloys were used, the strength was lower than that of the examples that were three-phase alloys. In particular, Comparative Example 4 increased the Fe content to 20%, but the strength did not improve much. In Comparative Example 5, Sn was added as a trace element, but the strength was not improved so much.
In addition, although the comparative examples 2 and 3 are the same compositions, the conditions and frequency | count of the aging treatment at the time of manufacture, and the workability were changed like Example 1-3.
Further, in Comparative Examples 6 and 7 made of Cu—Ag alloy, not only the strength was lower than that of the example of a three-phase alloy, but also the heat resistance was lowered. Among these, since Comparative Example 7 added Zr as a trace element, the heat resistance was slightly improved, but the strength was not improved.
In the case of Comparative Example 8 in which the Fe content is less than 7%, the Fe phase was not formed so as to contribute to the strength, so that the three-phase alloy was not formed, and the strength was higher than that in Example 5 in which the Ag content was the same. Declined.
Furthermore, in Examples 7 to 10 to which trace elements were added, the heat resistance was further excellent as compared with the other examples.

As is clear from Table 2, each of the examples subjected to ARB was excellent in both strength (0.2% yield strength) and conductivity. Each example was also excellent in heat resistance.
In Examples 11 and 13 in which ARB was performed, the strength was improved as compared with Comparative Examples 10 and 11 having the same composition and the same degree of processing. Further, in Examples 11 and 12 in which ARB was performed, the strength was improved as compared with Comparative Example 9 having the same final plate thickness. Further, in the case of Example 12 in which ARB was performed three times, the strength was significantly improved as compared with the Example in which Fe and Ag had the same composition.
From the above, it is preferable to perform ARB, and d ≦ 400 nm and 10 ≦ At ₂ .
Furthermore, in the case of Example 13 to which a trace element was added, the heat resistance was further excellent as compared with the other examples.

The organization of each material is shown in FIGS.
FIG. 4 is a view showing an SEM BSE image of the structure of the sample (ingot) before rolling of Example 11 (Cu-15Fe-4Ag). In FIG. 4, the black region indicates the Fe phase, the white region indicates the Ag phase, and the gray region indicates the Cu matrix. 5, 6, and 7 are diagrams showing metal micrographs of samples of Comparative Example 3 (Cu-15Fe), Comparative Example 4 (Cu-20Fe), and Example 1 (Cu-15Fe-4Ag) before rolling, respectively. is there. In each figure, the black region indicates the Fe phase, and the white region indicates the Cu matrix (the Ag phase is not visible under the observation conditions). As is apparent from FIGS. 5 to 7, even when the Fe content of the Cu—Fe (two-phase) alloy is increased to 20%, the number of Fe phases does not increase, but the Cu—Fe—Ag (three phases) increases. ) By using an alloy, the Fe phase crystallizes finely.

It is the figure which showed typically the rolling material structure | tissue of the alloy of this invention. It is a figure which shows the coarse Fe phase in the structure | tissue of the sample after rolling. It is process drawing which showed the outline of an example of ARB typically. It is a figure which shows the BEM image of SEM of the structure | tissue of the sample (ingot) before rolling. It is a figure which shows the structure | tissue of the sample before rolling. It is another figure which shows the structure | tissue of the sample before rolling. It is another figure which shows the structure | tissue of the sample before rolling.

Explanation of symbols

1A, 1B Rolled material J Rolled material tip 10 Roll 1C, 1D, 1E, 2 Rolled material 1x, 4 Fe phase and Ag phase

Claims (7)

  Fe containing 7% or more and 25% or less of Fe by mass%, containing 3% or more and 10% or less of Ag, consisting of the balance Cu and unavoidable impurities, Cu parent phase, Fe phase containing Fe of 70% or more, and Ag A high-strength, high-conductivity copper alloy characterized in that an Ag phase containing 50% or more coexists.   Furthermore, the high intensity | strength of Claim 1 containing 0.05% or more and 1% or less in total of 1 type, or 2 or more types of trace elements chosen from the group of Sn, Mg, and Zr by the mass% High conductivity copper alloy.   It is a rolling material, The high intensity | strength highly conductive copper alloy of Claim 1 or 2 characterized by the above-mentioned.   The high thickness according to claim 3, wherein an average thickness d of the Cu matrix phase separated by an adjacent phase among the Fe phase and the Cu matrix phase satisfies a relationship of d ≦ 400 nm in the rolling surface direction. High strength copper alloy. 5. The high-strength and high-conductivity copper alloy according to claim 3, wherein an average aspect ratio At ₂ of the Fe phase satisfies a relationship of 10 ≦ At ₂ when viewed from a cross-section perpendicular to rolling.   It is a manufacturing method of the high intensity | strength highly conductive copper alloy of Claim 1, 4 or 5, Comprising: Fe is contained 7% or more and 25% or less by mass%, Ag is contained 3% or more and 10% or less, and remainder Cu A first step of laminating two or more copper alloy rolling materials, which are made of inevitable impurities and coexist with a Cu parent phase, an Fe phase containing 70% or more of Fe, and an Ag phase containing 50% or more of Ag; And a second step of rolling the rolled material in the stacking direction at least once in this order. The rolling material further contains 0.05% or more and 1% or less in total of one or more trace elements selected from the group consisting of Sn, Mg, and Zr by mass%. The manufacturing method of the high intensity | strength highly conductive copper alloy of description.