Copper alloy, copper alloy plastic processing material, component for electronic / electrical machine, component for flexible device, component for heat radiation, metal seal material

Abstract

To provide a copper alloy excellent in conductivity while having a sufficiently large elastic deformation amount with a low Young's modulus and unlikely to cause a plastic deformation even under a large deformation.SOLUTION: A copper alloy has a composition including 15-57 mass% Zn, 12 mass% or less Al, satisfying A+5×B≥30 and A+3.5×B≤57 in which the Zn content is A mass% and the Al content is B mass%, and a balance Cu with inevitable impurities. A volume fraction in a β phase is 50% or more. an average of KAM (Kernel Average Misorientation) values of the β phase is 2.0° or less obtained when a measurement area of 1 mm2 or more is measured at a measurement interval 1 μm step by an EBSD method and measured excluding a measurement point with a CI value of 0.1 or less analyzed by data analysis software OIM.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to, for example, a copper alloy suitable for parts for electric and electronic equipment such as home appliances, semiconductor parts such as lead frames, printed wiring boards, heat sinks, switch parts, bus bars, connectors, etc., a copper alloy plastic working material made of this copper alloy, parts for electronic and electric equipment, parts for flexible devices, parts for heat dissipation, and metal sealing materials.

Background Art

[0002] Conventionally, copper or copper alloys excellent in electrical conductivity and heat conductivity have been used for parts for electric and electronic equipment such as terminals, bus bars, lead frames, and heat dissipation members. As copper alloys for the above-mentioned various uses, for example, as shown in Patent Documents 1-3, Cu-Zn based alloys (so-called brass) are used. In these Patent Documents 1-3, various elements other than Cu and Zn are added in order to ensure strength and workability.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in order to improve the usability of electronic and electrical devices, the components for electronic and electrical devices have been made flexible. Therefore, among the materials constituting the components for electronic and electrical devices, those having a low Young's modulus so that elastic deformation can be easily performed, and having a large elastic deformation amount so that even when receiving a large deformation, plastic deformation does not occur and the material returns to its original shape are required. Here, in conventional copper alloys such as those described in Patent Documents 1-3, the Young's modulus does not decrease, and the elastic deformation amount cannot be made sufficiently large, and there is a risk of easily undergoing plastic deformation when receiving a large deformation.

[0005] In Patent Document 4, a copper-based alloy that exhibits a large pseudoelastic deformation due to shape memory characteristics and superelastic characteristics while maintaining excellent workability has been reported. However, the Young's modulus is not sufficiently low and the deformation is not easy. In addition, when the conductivity is not disclosed and the conductivity is low, there is a problem that heat generation is large and energy loss is large when energized.

[0006] This invention has been made in view of the above-described circumstances, and provides a copper alloy having excellent conductivity, a low Young's modulus, a sufficiently large elastic deformation amount, and being less likely to undergo plastic deformation even when receiving a large deformation, a copper alloy plastic processed material made of this copper alloy, components for electronic and electrical devices, components for flexible devices, components for heat dissipation, and a metal sealing material.

Means for Solving the Problems

[0007] As a result of intensive studies by the inventors to solve the above problems, the following findings were obtained. It became clear that in order to obtain a copper material with a low Young's modulus, it is important to "obtain many β phases" and "reduce the strain inside the material". The β phase that appears in copper alloys has a lower Young's modulus than the α phase used in ordinary copper alloys. Therefore, the Young's modulus can be reduced by obtaining many β phases. Furthermore, by reducing the strain inside the β phase, there is no inhibition of deformation inside the β phase, and it becomes possible to obtain an even lower Young's modulus. In addition, by making the strain distribution within the material uniform, there are no parts that are locally difficult to deform, and the entire material deforms uniformly, thereby obtaining a lower Young's modulus. From the above, it has become clear that obtaining a large amount of β-phase with small and uniformly dispersed strain is important for reducing the Young's modulus of the copper alloy.

[0008] The present invention has been made based on the above findings. The copper alloy of Aspect 1 of the present invention contains 15% by mass or more and 57% by mass or less of Zn, contains 12% by mass or less of Al, where the content of Zn is A% by mass and the content of Al is B% by mass, satisfying A + 5×B ≧ 30 and A + 3.5×B ≦ 57, and the balance is composed of Cu and unavoidable impurities. The volume fraction of the β-phase is 50% or more, and the average value of the KAM (Kernel Average Misorientation) value of the β-phase measured at a measurement interval of 1 μm step for a measurement area of 1 mm 2 or more, excluding the measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less, is 2.0° or less.

[0009] According to the copper alloy of Aspect 1 of the present invention, it contains 15% by mass or more and 57% by mass or less of Zn, contains 12% by mass or less of Al, where the content of Zn is A% by mass and the content of Al is B% by mass, satisfying A + 5×B ≧ 30 and A + 3.5×B ≦ 57, and the balance is composed of Cu and unavoidable impurities. Therefore, it has excellent strength and conductivity and can have good thermal conductivity. In addition, the β-phase can be sufficiently formed. And since the volume fraction of the β-phase is 50% or more and the average value of the KAM value of the β-phase is 2.0° or less, the proportion occupied by the β-phase is large and the strain is sufficiently small. Therefore, the Young's modulus is sufficiently low and elastic deformation becomes easy. As a result, the amount of elastic deformation becomes sufficiently large, and even when subjected to large deformation, it is difficult to plastically deform easily and can be suitably used for applications where flexibility is required.

[0010] The copper alloy of Embodiment 2 of the present invention is characterized in that, in the copper alloy of Embodiment 1 of the present invention, it further contains 0.005% by mass or more and 10% by mass or less of Ni. According to the copper alloy of Embodiment 2 of the present invention, since it contains 0.005% by mass or more and 10% by mass or less of Ni, solid solution strengthening by Ni and the formation of precipitates containing Ni and Al can further improve the strength.

[0011] The copper alloy of Embodiment 3 of the present invention is characterized in that, in the copper alloy of Embodiment 1 or Embodiment 2 of the present invention, it further contains one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag in a total amount of 0.0005% by mass or more and 2.5% by mass or less. According to the copper alloy of Embodiment 3 of the present invention, since it contains one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag in a total amount of 0.0005% by mass or more and 2.5% by mass or less, while maintaining the conductivity, it can suppress the plastic deformation of the β phase and further increase the elastic deformation amount.

[0012] The copper alloy of Embodiment 4 of the present invention is characterized in that, in any one of the copper alloys of Embodiments 1 to 3 of the present invention, it further contains one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, mischmetal (MM) in a total amount of 0.0005% by mass or more and 2.5% by mass or less. According to the copper alloy of Embodiment 4 of the present invention, since it contains one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, mischmetal (MM) in a total amount of 0.0005% by mass or more and 2.5% by mass or less, while maintaining the conductivity, it can suppress the plastic deformation of the β phase and further increase the elastic deformation amount.

[0013] The copper alloy of Embodiment 5 of the present invention is characterized in that, in any one of the copper alloys of Embodiments 1 to 4 of the present invention, the standard deviation of the KAM value of the β phase is 0.75° or less. According to the copper alloy of Embodiment 5 of the present invention, since the standard deviation of the KAM value of the β phase is 0.75° or less, strain is not localized, deformation is not inhibited by strain, and the Young's modulus can be surely lowered.

[0014] The copper alloy of Embodiment 6 of the present invention is characterized in that, in any one of the copper alloys of Embodiments 1 to 5 of the present invention, when having an α phase, the average value of the KAM value of the α phase is 2.0° or less. According to the copper alloy of Embodiment 6 of the present invention, there may be an α phase in addition to the β phase. Since the average value of the KAM value of this α phase is 2.0° or less, the strain is sufficiently small and the Young's modulus can be kept low.

[0015] The copper alloy of Embodiment 7 of the present invention is characterized in that, in any one of the copper alloys of Embodiments 1 to 6 of the present invention, the average value of the GOS (Grain Orientation Spread) value of the β phase is 2.0° or less. According to the copper alloy of Embodiment 7 of the present invention, the average value of the GOS value of the β phase is 2.0° or less, strain is not localized, and the Young's modulus can be further kept low.

[0016] The copper alloy of Embodiment 8 of the present invention is characterized in that, in any one of the copper alloys of Embodiments 1 to 7 of the present invention, the Young's modulus is 100 GPa or less. According to the copper alloy of Embodiment 8 of the present invention, since the Young's modulus is 100 GPa or less, the Young's modulus is sufficiently low, elastic deformation becomes easy, and it can be suitably used for applications where flexibility is required.

[0017] The copper alloy of Embodiment 9 of the present invention is characterized in that, in any one of the copper alloys of Embodiments 1 to 8 of the present invention, the maximum elastic strain is 0.4% or more. According to the copper alloy of Embodiment 9 of the present invention, the maximum elastic strain is 0.4% or more, and even when subjected to large deformation, it is difficult to plastically deform.

[0018] The copper alloy of Aspect 10 of the present invention is characterized in that, among the copper alloys of any one of Aspects 1 to 9 of the present invention, the conductivity is 10% IACS or more. According to the copper alloy of Aspect 10 of the present invention, since the conductivity is 10% IACS or more, conductivity is ensured, and it can be suitably used as a material for an energized member.

[0019] The copper alloy wrought product of Aspect 11 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0020] The component for electronic and electrical equipment of Aspect 12 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0021] The component for a flexible device of Aspect 13 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0022] The component for heat dissipation of Aspect 14 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0023] The metal sealing material of Aspect 15 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

Advantages of the Invention

[0024] According to the present invention, there can be provided a copper alloy excellent in conductivity, having a low Young's modulus, a sufficiently large elastic deformation amount, and being less likely to undergo plastic deformation even when subjected to a large deformation, a copper alloy wrought product made of this copper alloy, a component for electronic and electrical equipment, a component for a flexible device, a component for heat dissipation, and a metal sealing material.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0026] Hereinafter, a copper alloy which is an embodiment of the present invention will be described. Note that the copper alloy of the present embodiment is used as a material for various parts such as parts for electronic and electrical equipment, parts for flexible devices, parts for heat dissipation, and metal sealing materials.

[0027] The copper alloy of the present embodiment contains 15% by mass or more and 57% by mass or less of Zn, contains 12% by mass or less of Al, sets the content of Zn as A% by mass, and the content of Al as B% by mass, satisfying A + 5×B ≧ 30 and A + 3.5×B ≦ 57, and the balance is composed of Cu and inevitable impurities. Further, in the copper alloy of the present embodiment, it may further contain 0.005% by mass or more and 10% by mass or less of Ni.

[0028] Further, in the copper alloy of the present embodiment, it may further contain one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag in a total range of 0.0005% by mass or more and 2.5% by mass or less. Further, in the copper alloy of the present embodiment, it may further contain one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, mischmetal (MM) in a total range of 0.0005% by mass or more and 2.5% by mass or less.

[0029] And, in the copper alloy of the present embodiment, the volume fraction of the β phase is 50% or more, and excluding the measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less when measuring a measurement area of 1 mm or more at a measurement interval of 1 μm step by the EBSD method, the average value of the KAM (Kernel Average Misorientation) value of the β phase measured is 2.0° or less. 2 The average value of the KAM (Kernel Average Misorientation) value of the β phase measured is 2.0° or less, excluding the measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less when measuring a measurement area of 1 mm or more at a measurement interval of 1 μm step by the EBSD method.

[0030] In addition, in the copper alloy of the present embodiment, the standard deviation of the KAM value of the β phase is preferably 0.75° or less. Furthermore, in the copper alloy of the present embodiment, the average value of the GOS (Grain Orientation Spread) value of the β phase is preferably 2.0° or less. In addition, in the copper alloy of the present embodiment, when it has an α phase, the average value of the KAM value of this α phase is preferably 2.0° or less. Also, the standard deviation of the KAM value of the α phase is preferably 0.75° or less.

[0031] Here, in the copper alloy of the present embodiment, the Young's modulus is preferably 100 GPa or less. In addition, in the copper alloy of the present embodiment, the maximum elastic strain is preferably 0.4% or more. Furthermore, in the copper alloy of the present embodiment, the conductivity is preferably 10% IACS or more.

[0032] In the copper alloy of the present embodiment, the reasons for defining the component composition, crystal structure, and various properties as described above will be explained below.

[0033] (Zn) The copper alloy of the present embodiment has Cu and Zn as main components. Here, when the Zn content is less than 15% by mass, the β phase does not sufficiently exist, the volume fraction of the β phase becomes less than 50%, and the Young's modulus may increase. Also, when the Zn content exceeds 57% by mass, a very brittle γ phase appears and the workability greatly deteriorates. Therefore, in the present embodiment, the Zn content is set within the range of 15% by mass or more and 57% by mass or less. Thereby, it can be excellent in strength and conductivity and can have good thermal conductivity. Here, the Zn content is preferably 18% by mass or more, and more preferably 20% by mass or more. Also, the Zn content is preferably 56% by mass or less, and more preferably 55% by mass or less.

[0034] (Al) By adding an appropriate amount of Al to the Cu-Zn alloy, it becomes possible to further improve the strength. Here, in order to suppress the brittle γ phase and make the β phase sufficiently present, the Al content should be 12 mass% or less, the Zn content is A mass%, the Al content is B mass%, and A + 5×B ≥ 30 and A + 3.5×B ≤ 57 are satisfied. When A + 5×B is less than 30, a sufficient β phase cannot be obtained and the Young's modulus becomes high. When A + 3.5×B exceeds 57, the proportion of the brittle γ phase increases and processing becomes difficult. In addition, the Al content is more preferably 11 mass% or less, and even more preferably 10 mass% or less. Also, the Al content is more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more. Also, A + 5×B is more preferably 31 or more, and even more preferably 32 or more. Furthermore, A + 3.5×B is more preferably 56 or less, and even more preferably 55 or less.

[0035] (Ni) By adding an appropriate amount of Ni to the Cu-Zn alloy, in addition to solid solution strengthening, precipitates containing Ni and Al are formed by adding together with Al, making it possible to further improve the strength. Here, in order to obtain the effect of improving the strength by Ni without significantly reducing the conductivity, the Ni content is preferably in the range of 0.005 mass% or more and 10 mass% or less. In addition, the Ni content is more preferably 0.01 mass% or more, and even more preferably 0.1 mass% or more. Also, the Ni content is more preferably 9 mass% or less, and even more preferably 8 mass% or less. Also, when Ni is not intentionally added, the Ni content may be less than 0.005 mass%.

[0036] (Group C elements: one or more selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag) In the copper alloy of the present embodiment, by containing one or more Group C elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag, plastic deformation of the β-phase is suppressed, and the elastic deformation amount becomes larger. On the other hand, if a large amount of these Group C elements is contained, the conductivity may decrease. Therefore, in the copper alloy of the present embodiment, it is preferable that the total content of one or more Group C elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag is in the range of 0.0005% by mass or more and 2.5% by mass or less. Co, Fe, Sn, Mg, Ag are elements suitable for strengthening the β-phase, and their optimum composition is 0.0005% by mass to 1% by mass in total. Mn, Si, Be are elements effective for obtaining more β-phase in addition to strengthening the β-phase, and their optimum composition is 0.0005% by mass to 1% by mass in total. Sb, Cd, As are elements suitable for strengthening the β-phase, and their optimum composition is 0.0005% by mass to 0.5% by mass in total. In addition, the total content of Group C elements is more preferably 0.001% by mass or more, and even more preferably 0.005% by mass or more. Also, the total content of Group C elements is more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less. When Group C elements are not intentionally added, the total content of Group C elements may be less than 0.0005% by mass.

[0037] (Group D elements: one or more selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, MM) In the copper alloy of the present embodiment, by containing one or more Group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, MM, precipitates and compounds are formed, thereby suppressing plastic deformation of the β-phase and increasing the elastic deformation amount. On the other hand, if a large amount of these Group D elements is contained, the conductivity may decrease. Therefore, in the copper alloy of the present embodiment, it is preferable that the total content of one or more Group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and MM is in the range of 0.0005% by mass or more and 2.5% by mass or less. Ti, V, Cr, Zr, and MM are elements suitable for strengthening the β phase by reacting with oxygen, sulfur, P, B, C, etc. in the material to form compounds, and their optimal composition is 0.0005% by mass to 0.8% by mass in total. Nb, Mo, and W are elements suitable for strengthening the β phase, and their optimal composition is 0.0005% by mass to 0.5% by mass in total. P and C are elements suitable for deoxidizing the material and forming compounds with other elements to strengthen the β phase, and their optimal composition is 0.0005% by mass to 1% by mass in total. B is an element suitable for suppressing embrittlement of the material and forming compounds with other elements to strengthen the β phase, and its optimal composition is 0.0005% by mass to 1% by mass. In addition, the total content of Group D elements is more preferably 0.001% by mass or more, and even more preferably 0.005% by mass or more. Also, the total content of Group D elements is more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less. When Group D elements are not intentionally added, the total content of Group D elements may be less than 0.0005% by mass.

[0038] Examples of inevitable impurities other than the above-mentioned elements include Ba, Ca, rare earth elements, Ta, Re, Ru, Sr, Os, Rh, Ir, Pb, Pd, Pt, Au, Hf, Hg, Ga, In, Ge, Tl, N, Li, etc. These impurity elements may be contained within a range that does not affect the properties. Since these inevitable impurities may reduce the conductivity, it is preferable that the total amount is 2.5% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less.

[0039] (Volume fraction of β phase) In the Cu-Zn alloy, in addition to the β phase, the α phase and the γ phase may appear. Here, since the Young's modulus decreases when the β phase deforms, when the volume fraction of the β phase is less than 50%, the β phase cannot be deformed sufficiently and the Young's modulus becomes high. Therefore, in the copper alloy of the present embodiment, the volume fraction of the β phase is set to 50% or more. Note that the volume fraction of the β phase is preferably 60% or more, and more preferably 70% or more.

[0040] (Average value of KAM value of β phase) The KAM (Kernel Average Misorientation) value measured by EBSD is a value calculated by averaging the orientation differences between one pixel and the pixels surrounding it. Since the shape of the pixel is a regular hexagon, when the proximity order is 1, the average value of the orientation differences with the six adjacent pixels is calculated as the KAM value. By using this KAM value, local orientation differences, that is, the distribution of strain can be visualized. The less the amount of strain inside the material, the weaker the inhibition of deformation by the strain, and the lower the Young's modulus. Therefore, the average value of the KAM value of the β phase is preferably 2.0° or less, more preferably 1.75° or less, and even more preferably 1.50° or less.

[0041] (Standard deviation of KAM value of β phase) When the strain is localized, the standard deviation of the above-mentioned KAM value becomes large. In the region where the strain is localized, the deformation is inhibited by the strain, so the Young's modulus becomes high. Therefore, the standard deviation of the KAM value of the β phase is preferably 0.75° or less, more preferably 0.65° or less, and even more preferably 0.6° or less.

[0042] (Average value of GOS value of β phase) The GOS (Grain Orientation Spread) value measured by EBSD represents the average value of the differences between each pixel and the average angle θ within the crystal, calculated for all pixels within the grain, and represents the average of these differences. Here, the average value is calculated using the number of each crystal, not the size of the crystal region. That is, a large GOS value indicates that the strain present in the grain is localized. Therefore, when the GOS value is high, i.e., the strain is unevenly distributed, locally deformed parts are generated, resulting in a high Young's modulus. Therefore, the average value of the GOS value of the β phase is preferably 2.0° or less, more preferably 1.75° or less, and even more preferably 1.50° or less. Here, the average value is calculated using the number of grains.

[0043] (Average value and standard deviation of the KAM value of the α phase) In the copper alloy of this embodiment, in addition to the β phase, the α phase may exist. When the α phase exists, it is also preferable that the amount of strain in this α phase is small. Also, it is preferable that the strain is not localized in the α phase. Therefore, the average value of the KAM value of the α phase is preferably 2.0° or less, more preferably 1.75° or less, and even more preferably 1.50° or less. Also, the standard deviation of the KAM value of the α phase is preferably 0.75° or less, more preferably 0.65° or less, and even more preferably 0.6° or less.

[0044] (Young's modulus) In the copper alloy of this embodiment, a low Young's modulus is required so that elastic deformation can be easily achieved. Specifically, in the copper alloy of this embodiment, the Young's modulus is preferably 100 GPa or less. Furthermore, the Young's modulus is more preferably 90 GPa or less, and even more preferably 80 GPa or less.

[0045] (Maximum elastic strain) In the copper alloy of the present embodiment, even when it undergoes large deformation, it is required to ensure an elastic deformation amount so that it does not easily plastically deform. Specifically, in the copper alloy of the present embodiment, it is preferable that the maximum elastic strain is 0.4% or more. Note that the maximum elastic strain is more preferably 0.45% or more, and even more preferably 0.5% or more.

[0046] (Conductivity) In the copper alloy of the present embodiment, when the conductivity is 10% IACS or more, it is particularly suitable as a material for the current-carrying member, which is a component for electric and electronic equipment. Note that the conductivity of the copper alloy of the present embodiment is preferably 12% IACS or more, and more preferably 14% IACS or more.

[0047] Next, an example of a method for manufacturing the copper alloy of the present embodiment will be described with reference to the flowchart shown in FIG. 1.

[0048] (Melting and casting process S01) First, the above-described elements are added to the copper melt obtained by melting the oxygen-free copper raw material to adjust the components, and a copper alloy melt is produced. Note that for the addition of various elements, elemental substances, master alloys, etc. can be used. Alternatively, a raw material containing the above-described elements may be melted together with the copper raw material. Here, each element is preferably a so-called 3N with a purity of 99.9 mass% or more, or a so-called 4N with a purity of 99.99 mass% or more. In the melting process, for reducing the hydrogen concentration, atmospheric melting is performed in an inert gas atmosphere (e.g., Ar gas) with a low vapor pressure of H 2 O, and it is preferable to minimize the holding time during melting. Then, the component-adjusted copper alloy melt is poured into a mold to produce an ingot. Note that when considering mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0049] (Hot working process S02) Hot working is performed on the obtained ingot to introduce strain and deform the shape to a predetermined size. In hot working, by introducing strain, a high strain can be applied in a state where the crystals are coarse, so that the material homogeneity can be improved. In the hot working step S02, since it is necessary to break the casting structure, a certain working ratio is required. The total working ratio needs to be 50% or more, preferably 55% or more, and more preferably 60% or more. The plastic working method is not particularly limited, but when the final shape is a plate or strip, it is preferable to adopt rolling. In the case of wire or bar, it is preferable to adopt extrusion, groove rolling, and in the case of a bulk shape, it is preferable to adopt forging or pressing.

[0050] (Intermediate temperature working step S03) Next, intermediate temperature working is performed on the obtained hot worked material to introduce strain while causing a phase transformation and deform the shape to a predetermined size. In this intermediate temperature working step S03, in a temperature range of 200°C or higher and 600°C or lower where the α + β phase is stable and a sufficient diffusion rate can be obtained, by performing multiple passes with an average working ratio of 20% or less per pass, strain is preferentially applied to the β phase that is easy to deform. Also, the total working ratio in the intermediate temperature working step S03 needs to be 20% or more, preferably 25% or more, and more preferably 30% or more. The plastic working method is not particularly limited, but when the final shape is a plate or strip, it is preferable to adopt rolling. In the case of wire or bar, it is preferable to adopt extrusion, groove rolling, and in the case of a bulk shape, it is preferable to adopt forging or pressing.

[0051] (First heat treatment step S04) Next, heat treatment is performed in the temperature range of the α + β phase to achieve homogenization and / or solution treatment, precipitate fine α phases, and cause recrystallization while obtaining a uniformly dispersed β phase. Here, the heat treatment method is not particularly limited, but it is preferably performed in a non-oxidizing or reducing atmosphere. Also, the heat treatment temperature needs to be 600°C or lower, preferably 550°C or lower. On the other hand, if the temperature is too low, diffusion will be insufficient, so it needs to be 350°C or higher. Also, the cooling method after heat treatment is carried out by a method such as water quenching with a cooling rate of 200°C / min or higher. Note that the warm rolling process and the first heat treatment process may be repeated multiple times.

[0052] (Cold working process S05) After the first heat treatment process S04, cold working is carried out. The processing temperature is in the range of -200°C or higher and 400°C or lower. Also, the total processing rate is 30% or higher, and a high strain is applied to obtain a uniform strain distribution. Note that in this cold working process S05, there is no particular limitation on the processing method, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be adopted. In this embodiment, wire drawing is performed.

[0053] (Second heat treatment process S06) Next, in order to form a large amount of β phase, heat treatment is performed on the cold worked material. By applying high strain to the cold worked material and performing heat treatment under high temperature conditions with a slow heating rate and a fast cooling rate, the proportion of the β phase can be increased, and the structure with an average KAM value of the β phase of 2.0° or less can be frozen. Here, the heat treatment method is not particularly limited, but it is preferably carried out in a non-oxidizing or reducing atmosphere. Also, the heat treatment temperature needs to be high. When the temperature is low, a sufficient amount of β phase cannot be obtained, so the heat treatment temperature is preferably 600°C or higher, more preferably 700°C or higher. On the other hand, if the heat treatment temperature is too high, it will exceed the melting point of the material, so the heat treatment temperature needs to be 1000°C or lower. Furthermore, the heating rate needs to be slow at 10°C / min or lower. By slowing down the heating rate, a structure with an average KAM value of the β phase of 2.0 or less can be obtained. On the one hand, for the cooling method, a method with a cooling rate of 200 °C / min or more, such as water quenching, is required. When the cooling rate is slow, phases other than the β-phase may appear frequently during cooling, and the proportion occupied by the β-phase may decrease. In addition, for the purpose of improving the efficiency of rough machining and homogenizing the structure, hot working may be performed after the heat treatment.

[0054] (Tempering process S07) For the recrystallized heat-treated copper material, tempering may be performed to adjust the material strength. When low material strength is required, tempering may not be necessary. The final thickness and wire diameter are not particularly limited. In this tempering process S07, the processing method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be adopted.

[0055] Through the above processes, the copper alloy (copper alloy plastic processed material) of this embodiment will be manufactured. The means for adjusting the volume fraction of the β-phase, the average value of the KAM value, etc. within the above range is not limited to a specific method. For example, it can be achieved by controlling the temperature of the warm working process S03, the temperature of the second heat treatment process S06, the heating rate, the cooling temperature, etc. as described above.

[0056] According to the copper alloy of this embodiment configured as above, it contains 15% by mass or more and 57% by mass or less of Zn, 12% by mass or less of Al. Let the content of Zn be A% by mass and the content of Al be B% by mass, satisfying A + 5×B ≥ 30 and A + 3.5×B ≤ 57, with the balance being Cu and inevitable impurities. Therefore, it has excellent strength, conductivity, and can have good thermal conductivity. And since the volume fraction of the β-phase is 50% or more and the average value of the KAM value of this β-phase is 2.0° or less, the proportion of the β-phase is large and the strain is sufficiently small, so the Young's modulus is sufficiently low and elastic deformation becomes easy. As a result, the amount of elastic deformation becomes sufficiently wide, and even when receiving a large deformation, it does not easily undergo plastic deformation, and it can be suitably used for applications where flexibilization is required.

[0057] In this embodiment, when further containing 0.005% by mass or more and 10% by mass or less of Ni, the strength can be further improved.

[0058] In this embodiment, when further containing a total of 0.0005% by mass or more and 2.5% by mass or less of one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag, while maintaining the conductivity, plastic deformation of the β-phase can be suppressed and the amount of elastic deformation can be further increased.

[0059] In this embodiment, when further containing a total of 0.0005% by mass or more and 2.5% by mass or less of one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, MM, while maintaining the conductivity, plastic deformation of the β-phase can be suppressed and the amount of elastic deformation can be further increased.

[0060] In this embodiment, when the standard deviation of the KAM value of the β-phase is 0.75° or less, it means that the strain is not localized, the deformation is not inhibited by the strain, and the Young's modulus can be surely lowered. As a result, the amount of elastic deformation becomes even larger, and even when receiving a large deformation, it does not easily undergo plastic deformation, and it can be suitably used for applications where flexibilization is required.

[0061] In the present embodiment, when it has an α-phase and the average value of the KAM value of this α-phase is 2.0° or less, it has an α-phase in addition to the β-phase. However, since the average value of the KAM value of this α-phase is 2.0° or less, the strain is sufficiently small, and the Young's modulus can be suppressed to be low. As a result, the elastic deformation amount becomes even larger, and even when it receives a large deformation, it does not easily undergo plastic deformation, and it can be suitably used for applications where flexibility is required.

[0062] In the present embodiment, when the average value of the GOS (Grain Orientation Spread) value of the β-phase is 2.0° or less, the strain is not localized, and the Young's modulus can be suppressed to be low. As a result, the elastic deformation amount becomes even larger, and even when it receives a large deformation, it does not easily undergo plastic deformation, and it can be suitably used for applications where flexibility is required.

[0063] In the present embodiment, when the maximum elastic strain is 0.4% or more, the elastic deformation amount is sufficiently ensured, and even when it receives a large deformation, it does not easily undergo plastic deformation, and it can be suitably used for applications where flexibility is required.

[0064] In the present embodiment, when the Young's modulus is 100 GPa or less, the Young's modulus is sufficiently low, and elastic deformation can be easily performed. It can be suitably used for applications where flexibility is required, such as flexible devices, printed wirings used therein, and further metal sealing materials.

[0065] In the present embodiment, when the conductivity is 10% IACS or more, the conductivity is ensured, and it can be suitably used as a material for parts for electronic and electrical devices such as terminals, current-carrying members, probe needles, thermal interface materials, and heat dissipation parts.

[0066] The copper alloy, which is an embodiment of the present invention, has been described above. However, the present invention is not limited thereto and can be appropriately modified without departing from the technical idea of the invention. In the above-described embodiment, an example of the manufacturing method of the copper alloy has been described. However, the manufacturing method of the copper alloy is not limited to that described in the above-described embodiment, and an existing manufacturing method may be appropriately selected for manufacturing.

Examples

[0067] The results of the confirmation experiments conducted to confirm the effects of the present invention will be described below.

[0068] First, raw materials made of pure copper with a purity of 99.999 mass% or more and each additive element of 99.9% or more were prepared, loaded into a high-purity graphite crucible, and high-frequency melted in an atmosphere furnace with an Ar gas atmosphere. It was adjusted to the component composition shown in Table 1 and poured into a heat-insulating material (isowool) mold to produce an ingot. The size of the ingot was about 100 mm in diameter × about 150 to 200 mm in length.

[0069] Next, hot working (hot extrusion) was performed on the obtained ingot under the conditions shown in Table 2 in an Ar gas atmosphere. In order to remove the oxide film on the surface after hot working, surface lathe processing was performed and processed to a predetermined size. Then, the size was adjusted as appropriate to obtain the final shape. Then, warm working, primary heat treatment, cold working, secondary heat treatment, and tempering were performed under the conditions shown in Table 2 to produce wire rods for property evaluation made of the copper alloys of the present invention examples and comparative examples with a final wire diameter of 1 mm to 5 mm.

[0070] The copper alloys of the present invention examples and comparative examples obtained as described above were evaluated as follows. The evaluation results are shown in Table 3.

[0071] (Composition analysis) Measurement samples were taken from the obtained ingots and measured using a high-frequency inductively coupled plasma optical emission spectrometer (ICP).

[0072] (Volume fraction of β phase) A 10-mm-long sample was cut from the wire for property evaluation. After mechanical polishing of the cross-section perpendicular to the processing direction using waterproof abrasive paper and diamond abrasive grains, finish polishing was performed using a colloidal silica solution. This sample was analyzed using an EBSD measurement device (Quanta FEG 450 manufactured by FEI, OIM Data Collection manufactured by EDAX / TSL (currently AMETEK)) and analysis software (OIM Data Analysis ver. 8.6 manufactured by EDAX / TSL (currently AMETEK)) at an acceleration voltage of 15 kV for the electron beam and a measurement interval of 1 μm step over a measurement area of 1 mm 2 or more. Excluding the measurement points where the CI value was 0.1 or less, the angular difference between each grain was analyzed, the crystal phase was identified, the ratio of the area identified as the β phase in each measurement field was defined as the area fraction of the β phase, and the average area fraction over three or more fields was defined as the volume fraction of the β phase.

[0073] (KAM value, GOS value) In the same manner as the method described for the volume fraction of the β phase above, analysis was performed using an EBSD measurement device and analysis software to obtain the KAM value for all pixels of the β phase, and the average value and standard deviation were calculated. Also, the average value of the GOS value was calculated. When the α phase was present, the KAM value for all pixels of the α phase was also obtained, and the average value and standard deviation were calculated.

[0074] (Conductivity) A 60-mm-long test piece was taken from the wire for property evaluation, and the electrical resistance was determined by the four-terminal method. Also, the dimensions of the test piece were measured using a micrometer, and the volume of the test piece was calculated. Then, the conductivity was calculated from the measured electrical resistance value and volume. The test piece was taken so that its longitudinal direction was parallel to the processing direction of the wire for property evaluation.

[0075] (Young's modulus) The Young's modulus E was determined from the slope in the elastic region of the stress-strain curve by attaching a contact extensometer to the above test piece and performing a mechanical test according to JIS Z 2241. The strain rate was 5×10 ―4 s ―1 was used.

[0076] (Maximum elastic strain) In the same tensile test as described above, as shown in Fig. 2, stress was applied and removed repeatedly so that the applied strain increased by 0.5% each time, and the difference between the applied strain and the residual strain when the residual strain first occurred during unloading was defined as the maximum elastic strain. Maximum elastic strain = Applied strain - Residual strain

[0077] [Table 1]

[0078] [Table 2]

[0079] [Table 3]

[0080] In Comparative Example 1, the composition was not appropriate and the volume fraction of the β-phase was 0%, the Young's modulus was as high as 110 GPa, and the maximum elastic strain was as small as 0.1%. In Comparative Example 2, the composition was not appropriate and the volume fraction of the β-phase was 0%, the Young's modulus was as high as 115 GPa, and the maximum elastic strain was as small as 0.1%. In Comparative Example 3, the volume fraction of the β-phase was 45%, the average value of the KAM value of the β-phase was 2.12°, the Young's modulus was as high as 120 GPa, and the maximum elastic strain was as small as 0.2%. In Comparative Example 4, the volume fraction of the β-phase was 70%, but the average value of the KAM value of the β-phase was 2.11°, the Young's modulus was as high as 112 GPa, and the maximum elastic strain was as small as 0.3%. In Comparative Example 5, the volume fraction of the β-phase was 95%, but the average value of the KAM value of the β-phase was 2.33°, the Young's modulus was as high as 105 GPa, and the maximum elastic strain was as small as 0.3%. In Comparative Examples 6, 7, and 8, A + 3.5 × B exceeded 57, resulting in poor workability and the inability to produce the wire rods for property evaluation.

[0081] On the other hand, in Invention Examples 1 - 17, the volume fraction of the β phase was 50% or more, the average value of the KAM value of the β phase was 2.0° or less, and the maximum elastic strain became as large as 0.4% or more. Further, the conductivity was 10% IACS or more, indicating excellent conductivity.

[0082] As a result of the above confirmation experiments, it was confirmed that according to the present invention, it is possible to provide a copper alloy that has excellent conductivity, a low Young's modulus, a sufficiently large elastic deformation amount, and is less likely to undergo plastic deformation even when subjected to large deformation.

Claims

1. It contains Zn of 15% by mass or more and 57% by mass or less, contains Al of 12% by mass or less, the content of Zn is A% by mass, the content of Al is B% by mass, and it satisfies A + 5×B ≥ 30 and A + 3.5×B ≤ 57, and the balance is made of Cu and inevitable impurities, the volume fraction of the β phase is 50% or more, 1mm by EBSD method ２ The above measurement area is measured at measurement intervals of 1 μm, and the average value of the KAM (Kernel Average Misorientation) value of the β phase measured excluding measurement points where the CI value analyzed by data analysis software OIM is 0.1 or less is 2.0 ° or less. Copper alloy characterized by the above.

2. The copper alloy according to claim 1, further containing Ni of 0.005% by mass or more and 10% by mass or less.

3. The copper alloy according to claim 1 or claim 2, further containing, in total, one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag in the range of 0.0005% by mass or more and 2.5% by mass or less.

4. The copper alloy according to claim 1 or claim 2, further containing, in total, one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, misch metal in the range of 0.0005% by mass or more and 2.5% by mass or less.

5. The copper alloy according to claim 1, wherein the standard deviation of the KAM value of the β phase is 0.75° or less.

6. When having an α phase, the copper alloy according to claim 1 or claim 2, wherein the average value of the KAM value of the α phase is 2.0° or less.

7. The copper alloy according to claim 1 or claim 2, wherein the average value of the GOS (Grain Orientation Spread) value of the β phase is 2.0° or less.

8. The copper alloy according to claim 1 or claim 2, wherein the Young's modulus is 100 GPa or less.

9. The copper alloy according to claim 1 or claim 2, wherein the maximum elastic strain is 0.4% or more.

10. The copper alloy according to claim 1 or claim 2, wherein the conductivity is 10% IACS or more.

11. A copper alloy plastic processed material, characterized by being made of the copper alloy according to claim 1 or claim 2.

12. Parts for electronic and electrical equipment, characterized by being made of the copper alloy according to claim 1 or claim 2.

13. Parts for flexible devices, characterized by being made of the copper alloy according to claim 1 or claim 2.

14. Parts for heat dissipation, characterized by being made of the copper alloy according to claim 1 or claim 2.

15. A metal sealing material characterized by being made of the copper alloy according to claim 1 or claim 2.

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