JP7167478B2 - Aluminum alloy wire rod and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to an aluminum alloy wire and a method for producing the same.

Electric wires and cables having conductors made of copper or copper alloys are used as wiring materials in applications such as railway vehicles, automobiles, and other electrical equipment. From the viewpoint of reducing energy consumption in automobiles and the like, there is a great demand for weight reduction of these electric wires and cables. Therefore, in recent years, the use of conductors made of aluminum or aluminum alloys, which have a lower specific gravity than copper or copper alloys, has been studied for electric wires and cables used in these applications.

For example, Patent Literature 1 proposes a method of adding alloy elements such as magnesium (Mg) and zirconium (Zr) to an aluminum alloy and causing aging precipitation of these elements. According to Patent Document 1, the strength, elongation, electrical conductivity and heat resistance of the conductor can be improved by employing such an aluminum alloy as the conductor. In addition, the heat resistance in Patent Document 1 indicates that the strength is 150 MPa or more when held at a temperature from room temperature to 150° C. for 1000 hours.

JP 2012-229485 A

By the way, in electric wires and cables used in railway vehicles and the like, when aluminum or an aluminum alloy is used for the conductor, the cross-sectional area of the conductor becomes larger than when copper is used. Since the wiring space for wiring electric wires and cables is limited in moving vehicles such as railway vehicles, the cross-sectional area of conductors made of aluminum or aluminum alloy is reduced as much as possible, and electric wires and cables are routed in the same wiring space as before. It is desired that However, when the cross-sectional area of a conductor made of aluminum or an aluminum alloy is reduced, it has been difficult to obtain a high level of strength, elongation, electrical conductivity and heat resistance in a well-balanced manner.

An object of the present invention is to provide an aluminum alloy wire having high levels of strength, elongation, electrical conductivity and heat resistance in a well-balanced manner.

According to one aspect of the invention,
A wire rod made of an aluminum alloy,
The aluminum alloy is
Co: 0.1 to 1.0% by mass, Zr: 0.2 to 0.5% by mass, Fe: 0.02 to 0.09% by mass, Si: 0.02 to 0.09% by mass, Mg: 0 to 0.2% by mass, Ti: 0 to 0.10% by mass, B: 0 to 0.03% by mass, Cu: 0 to 1.00% by mass, Ag: 0 to 0.50% by mass, Au: 0 to 0.50% by mass, Mn: 0 to 1.00% by mass, Cr: 0 to 1.00% by mass, Hf: 0 to 0.50% by mass, V: 0 to 0.50% by mass, Sc: 0 to 0.50% by mass, Ni: 0 to 0.50% by mass, the balance: having a chemical composition consisting of Al and inevitable impurities, and
Having a metal structure containing Al crystal grains and Al-Co-Fe compounds and Al-Zr compounds,
Tensile strength of 150 MPa or more,
Conductivity is 55% IACS or more,
The strength when heated at 200 ° C. for 10 years is 90% or more of the strength in the initial state,
An aluminum alloy wire is provided.

According to another aspect of the invention,
A method for manufacturing a wire rod made of an aluminum alloy,
Co: 0.1 to 1.0% by mass, Zr: 0.2 to 0.5% by mass, Fe: 0.02 to 0.09% by mass, Si: 0.02 to 0.09% by mass, Mg: 0 to 0.2% by mass, Ti: 0 to 0.10% by mass, B: 0 to 0.03% by mass, Cu: 0 to 1.00% by mass, Ag: 0 to 0.50% by mass, Au: 0 to 0.50% by mass, Mn: 0 to 1.00% by mass, Cr: 0 to 1.00% by mass, Hf: 0 to 0.50% by mass, V: 0 to 0.50% by mass, Sc: A preparation step of preparing a molten metal consisting of 0 to 0.50% by mass, Ni: 0 to 0.50% by mass, and the balance: Al and inevitable impurities;
a casting step of forming a casting material containing an Al—Co—Fe compound by quenching and casting the molten metal at a cooling rate that causes Co to crystallize while suppressing the crystallization of Zr;
A wire drawing step of drawing the cast material to form a drawn wire material;
an aging treatment step of subjecting the drawn wire material to aging treatment, and precipitating Zr dissolved in the Al phase as an Al—Zr compound;
The aluminum alloy has the chemical composition and a metal structure containing Al crystal grains, an Al—Co—Fe compound, and an Al—Zr compound, and the wire has a tensile strength of 150 MPa or more and an electrical conductivity of 55% IACS. As described above, the strength when heated at 200 ° C. for 10 years is configured to be 90% or more of the strength in the initial state,
A method for manufacturing an aluminum alloy wire is provided.

According to the present invention, it is possible to obtain an aluminum alloy wire having high levels of strength, elongation, electrical conductivity and heat resistance in a well-balanced manner.

FIG. 1 is a SIM (secondary ion microscope) image of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire of Example 4. FIG. FIG. 2 is a STEM (scanning electron microscope) dark-field image of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire of Example 4. FIG. 3 is an enlarged view of FIG. 3. FIG. 4 is a SIM (secondary ion microscope) image of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire of Comparative Example 1. FIG. FIG. 5 is a dark-field image of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire of Comparative Example 1, taken by STEM (scanning electron microscope). FIG. 6 is an enlarged view of FIG.

In order to solve the above-described problems, the present inventors appropriately changed the types of alloying elements, manufacturing conditions, and the like, and studied changes in various properties when the chemical composition of the aluminum alloy was changed. As a result, it was found that by using Co and Zr as alloying elements, the strength, elongation, electrical conductivity and heat resistance of the finally obtained aluminum alloy wire can be obtained at high levels in a well-balanced manner. The present invention has been made based on this finding.

<Aluminum alloy wire>
An aluminum alloy wire according to one embodiment of the present invention will be described below. In this specification, the numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits.

(chemical composition)
First, the chemical composition of an aluminum alloy (hereinafter simply referred to as an alloy) that constitutes an aluminum alloy wire (hereinafter simply referred to as an alloy wire) will be described.

The chemical composition of the alloy is Co: 0.1-1.0 mass %, Zr: 0.2-0.5 mass %, Fe: 0.02-0.09 mass %, Si: 0.02-0. 09% by mass, Mg: 0 to 0.2% by mass, Ti: 0 to 0.10% by mass, B: 0 to 0.03% by mass, Cu: 0 to 1.00% by mass, Ag: 0 to 0.00% by mass. 50 mass %, Au: 0-0.50 mass %, Mn: 0-1.00 mass %, Cr: 0-1.00 mass %, Hf: 0-0.50 mass %, V: 0-0. 50% by mass, Sc: 0 to 0.50% by mass, Ni: 0 to 0.50% by mass, balance: Al and unavoidable impurities.

Co is an essential component added to the alloy wire. As will be described later, in the manufacturing process (during casting and solidification) of the alloy wire, most of Co reacts with Al to form crystallized substances (Al—Co compounds), and the finally obtained alloy wire exists as a compound phase. The Al--Co compound actually exists in the form of an Al--Co--Fe compound that absorbs Fe that is inevitably present in the aluminum alloy. The Al--Co--Fe compound contributes to the refinement of recrystallized Al grains in the alloy and improves the elongation of the alloy wire. Co may reduce the electrical conductivity of the alloy. It is possible to obtain the effect of having a high level of strength, elongation, and heat resistance in a well-balanced manner. The Co content is preferably 0.2% by mass to 1.0% by mass, more preferably 0.3% by mass to 0.8% by mass.

Zr, like Co, is an essential component added during the production of the alloy wire. As will be described later, Zr exists in a solid solution state in the ingot (cast material) after casting, but precipitates as an Al—Zr compound in the alloy wire after aging heat treatment. The Al—Zr compound mainly contributes to improving the heat resistance of the alloy wire. If the Zr content is excessively high, it may reduce the ductility of the alloy during the manufacturing process of the alloy wire, thereby hindering the diameter reduction of the alloy wire. In this regard, by setting the Zr content to 0.2% by mass to 0.5% by mass, it is possible to maintain high ductility of the alloy and obtain desired heat resistance in the alloy wire. More preferably, the Zr content is 0.3% by mass to 0.4% by mass.

Fe is a component that is inevitably taken in from aluminum raw materials. Fe contributes to improving the strength of the alloy. When Fe crystallizes as FeAl ₃ during casting or precipitates as FeAl ₃ during aging heat treatment, it may reduce the ductility of the alloy and hinder the diameter reduction of the alloy wire during production. In the present embodiment, by blending Co, an Al--Co--Fe compound is formed by absorbing Fe when the Al--Co compound is crystallized. Accordingly, the formation of FeAl ₃ is suppressed by making Fe into an Al—Co—Fe compound. As a result, it is possible to improve the strength of the alloy while suppressing the decrease in ductility of the alloy. The content of Fe is preferably less than or equal to the content of Co from the viewpoint of absorption by the Al—Co compound, and is 0.02% by mass to 0.09% by mass. This makes it possible to obtain high strength while reducing the diameter of the alloy wire. The Fe content is preferably 0.04% by mass to 0.09% by mass. Incidentally, Fe may be added so as to have a predetermined content.

Si, like Fe, is a component that is inevitably taken in from aluminum raw materials. Si contributes to the improvement of the strength of the alloy by forming a solid solution in Al crystal grains of the alloy or precipitating together with Fe. Si, like Fe, may reduce the elongation of the alloy or hinder the reduction in diameter of the alloy wire. , it is possible to improve the strength while suppressing the decrease in elongation of the alloy. The Si content is preferably 0.04% by mass to 0.08% by mass. Incidentally, Si may be added so as to have a predetermined content.

Mg, Ti, B, Cu, Ag, Au, Mn, Cr, Hf, V, Sc, and Ni are optional components that are derived from the aluminum raw material and are added as appropriate. Here, the optional component indicates a component that may or may not be contained. Each alloy element suppresses the coarsening of Al phase crystal grains in the alloy wire and contributes to the improvement of its strength. Among them, Cu, Ag, and Au can be precipitated at grain boundaries to improve grain boundary strength. By setting the content of each alloying element within the above range, the elongation of the alloy is suppressed and the effect of each alloying element can be obtained.

The balance other than the above-mentioned components becomes Al and unavoidable impurities. Here, the unavoidable impurities are those that are unavoidably incorporated in the manufacturing process of the alloy wire, and are contained in such a small amount that the characteristics of the alloy wire are not affected. Examples of unavoidable impurities include Ga, Zn, Bi, and Pb.

From the viewpoint of the electrical conductivity of the alloy wire, the Al content is preferably 97% by mass or more, more preferably 98% by mass or more, and even more preferably 98.4% by mass or more.

(metal structure)
Next, the metal structure of the aluminum alloy will be described.

The metallographic structure of the alloy contains Al--Co--Fe compounds and Al--Zr compounds consisting of Al crystal grains, crystallized substances or precipitates, and these compounds are finely dispersed.

Here, the crystallized substance refers to a compound formed in the step of solidifying the molten metal by cooling when casting the aluminum alloy, or in the step of cooling the high-temperature cast material to near room temperature after solidification. . In other words, the crystallized substances are compounds formed in the aluminum alloy at the casting material stage.
The term "precipitate" refers to a compound formed by aging treatment in the stage of heating and holding a cast material that has been cooled to room temperature in a high-temperature atmosphere below the melting point. Specifically, it is a compound that is formed for the first time when a metal element solid-soluted in the Al phase of the cast material diffuses and agglomerates into the Al phase due to the aging treatment. In other words, the precipitates do not exist in the Al alloy at the stage of the cast material, but exist at the stage of the alloy wire rod after the aging treatment.

From the viewpoint of achieving higher levels of strength, elongation, electrical conductivity and heat resistance of the alloy, the metallic structure of the alloy is preferably a fine crystal structure in which the above compounds are finely dispersed. Specifically, in the metal structure of the alloy, in a cross section parallel to the longitudinal direction of the wire, the area occupied by Al crystal grains with a maximum grain size of 10 μm or less is preferably 90% or more in area ratio. In the metallographic structure having such an area ratio, most of the Al crystal grains are fine crystals of 10 μm or less, so the crystal grain boundaries formed between the crystal grains form a fine network structure. Due to the presence of two types of compounds, the Al--Co--Fe compound and the Al--Zr compound, in such grain boundaries and their neighboring regions, the compounds are finely and uniformly dispersed in the metal structure.

The grain size is the grain size of Al grains in a cross section along the longitudinal direction of an aluminum alloy wire in which Al grains and Al--Co--Fe compounds and Al--Zr compounds are present in the metal structure. Indicates maximum value.

In the metallographic structure, the number of Al-Co-Fe compounds per unit area (hereinafter simply referred to as number density) is preferably 50/100 µm ² or more in a cross section perpendicular to the longitudinal direction of the alloy wire. By dispersing the Al—Co—Fe compound at such a number density, the compound can be finely dispersed in the metal structure, and various properties can be obtained at a higher level and in a well-balanced manner in the alloy wire.

In the metallographic structure, the number of Al—Zr compounds per unit area (number density) is preferably 500/100 μm ² in a cross section perpendicular to the longitudinal direction of the alloy wire. By dispersing the Al—Zr compound at such a number density, the compound can be finely dispersed in the metal structure, and various properties can be obtained at a higher level and in a well-balanced manner in the alloy wire.

In the metallic structure, the size of the Al—Zr compound is preferably 5 nm or more and 100 nm or less. By reducing the size of the precipitates, the number of precipitates can be increased even when the content of the alloying element is reduced, and the effect of the precipitates can be obtained in a well-balanced manner. Moreover, since the ductility of the alloy can be maintained at a high level, the workability can be increased in the wire drawing process, and the diameter of the alloy wire can be further reduced.

Also, in the metallographic structure, the size of the Al-Co-Fe compound is preferably 20 nm or more and 500 nm or less. As with the Al--Zr compound, it is preferable to reduce the particle size of the Al--Co--Fe compound. Since Co atoms diffuse faster than Zr atoms in the Al structure, the size of the Al--Co--Fe compound increases more than that of the Al--Zr compound. As will be described later, the role of the Al-Co-Fe compound is to suppress the growth of recrystallized grains in the initial stage of aging heat treatment. Therefore, in the metallographic structure after aging heat treatment, there is no problem even if the size of the Al--Co--Fe compound exceeds that of the Al--Zr compound.

The shape of the compound is not particularly limited, but the Al--Co--Fe compound is preferably spherical or spheroidal. Although the Al--Zr compound is preferably spherical, it does not matter if it has an irregular shape. Note that the spheroidal shape refers to a shape that is circular in the direction perpendicular to the longitudinal direction of the wire and elliptical in the direction parallel to the longitudinal direction of the wire.

(Characteristics of aluminum alloy wire)
The aluminum alloy wire rod of the present embodiment is formed from an aluminum alloy having the chemical composition and metallographic structure described above, and has well-balanced strength, elongation, electrical conductivity, and heat resistance at high levels. Specifically, the alloy wire has a tensile strength of 150 MPa or more at room temperature and a tensile elongation of 8% or more. Moreover, it has a conductivity of 50% IACS or more. In addition, it has heat resistance such that the strength when heated at 200° C. for 10 years is 90% or more of the strength in the initial state. It should be noted that the "heat resistance in which the strength when heated at 200 ° C. for 10 years is 90% or more of the strength in the initial state" is obtained by heating the aluminum alloy wire at a specific temperature and time. Based on the isothermal softening curve of tensile strength, the temperature at which the tensile strength of the aluminum alloy wire is 10% lower than the tensile strength (initial tensile strength) before heating (for example, any temperature in the range of 300 ° C. to 400 ° C.) and time (for example, any time in the range of 600 sec to 3000000 sec) is Arrhenius plotted, and the time when the temperature in the Arrhenius plot is 200 ° C. (the time when the tensile strength decreases by 10%) is 10 means more than a year old. Specifically, it can be obtained by the heat resistance evaluation method in Examples described later.

The wire diameter of the alloy wire is not particularly limited, but from the viewpoint of flexibility, it is preferably 2 mm or less, more preferably 0.3 mm to 1 mm. In this embodiment, by making the alloy have a predetermined structure, it is possible to obtain various properties at a high level and in a well-balanced manner while keeping the wire diameter at 2 mm or less.

<Method for producing aluminum alloy wire>
Next, a method for manufacturing the aluminum alloy wire described above will be described. The aluminum alloy wire rod of the present embodiment can be manufactured by sequentially performing each step of a molten metal preparation step, a casting step, a forming step, a wire drawing step, and an aging treatment step. Each step will be described in detail below.

(Preparation process)
First, a molten metal for forming an aluminum alloy wire is prepared. In this embodiment, the Al raw material, the Co raw material, the Zr raw material, and, if necessary, other alloy raw materials are mixed and melted so that the molten metal has the chemical composition described above. The method of mixing and dissolving the raw materials is not particularly limited, and conventionally known methods can be used.

(Casting process)
Subsequently, the molten metal is cast to form a cast material. In the present embodiment, the molten metal is quenched and solidified at a cooling rate that allows Co to crystallize while suppressing Zr from crystallizing. As a result, the Al--Co--Fe compound is crystallized to form a cast material in which the Al--Co--Fe compound is dispersed.

Here, the knowledge obtained by the present inventors will be described with respect to the difference in behavior between Co and Zr due to rapid cooling in the casting stage.

According to the studies of the present inventors, it was found that Co and Zr differ in the easiness of crystallization and precipitation (precipitation rate) due to the difference in diffusion rate in the aluminum solid phase.

Specifically, the diffusion rate of Co in the Al solid phase is equal to or higher than the self-diffusion rate of Al. Moreover, the solid solubility of Co in the Al phase in the thermal equilibrium state is very small, less than 0.05% at maximum. Therefore, Co easily aggregates and crystallizes in the Al structure even immediately after being cast from the molten metal and solidified. Due to crystallization, most of Co is crystallized as a compound in the Al structure at the ingot (casting material) stage after casting.

In addition to the crystallized compound, Co atoms dissolved in the Al phase immediately after solidification also exist. Immediately after solidification, supersaturated Co atoms, which are more than the thermal equilibrium solid solubility, form a solid solution in the Al phase. However, Co atoms diffuse at high speed in the Al phase, so that Co atoms dissolved in a supersaturated solid solution aggregate in a relatively short period of time to form a compound phase. As a result, most of the added Co atoms exist as a compound phase with Al until the cast material is cooled to room temperature after casting and solidification, and the Co atoms dissolved in the Al phase have a thermal equilibrium concentration of It remains close to a small amount of less than 0.1%.

On the other hand, the diffusion rate of Zr in the Al phase is significantly lower than the self-diffusion rate of Al, and the precipitation rate in the Al structure is lower than that of Co. Moreover, the maximum solid solubility of Zr in the Al phase in the thermal equilibrium state is about 0.3 to 0.4%, which is several times larger than that of Co. For this reason, Zr is difficult to crystallize in the stage of the casting material after casting, and most of it exists in a supersaturated solid solution state in the Al structure. In addition, since Zr diffuses significantly slower than Co, the supersaturated solid-solution state is maintained as it is even when the cast material after casting is stored at room temperature for a long time. Zr in a supersaturated solid solution state can be precipitated by aging treatment, for example, by heating at a temperature of 300° C. or higher.

The present inventors paid attention to this difference in deposition rate and conducted a study. As a result, as the rate of cooling the molten metal is increased, most of the Co is crystallized as an Al—Co—Fe compound in the resulting cast material, while suppressing the crystallization of Zr and allowing Zr to form a solid solution. It has been found that it can be maintained According to such a cast material, it is possible to suppress wire breakage even when the wire is drawn at a high degree of working compared to a cast material in which Zr is crystallized, and it is possible to manufacture an alloy wire rod with a small wire diameter.

In the cast material, Co forms an Al-Co-Fe compound with Fe in the molten metal, so that Fe in a solid solution state that causes a decrease in electrical conductivity is small, and precipitates that cause a decrease in elongation ( FeAl ₃ ) is less. On the other hand, the Al-Co-Fe compound formed in the cast material is dispersed in the Al structure, and acts to suppress coarsening of Al crystal grains due to recrystallization in the aging heat treatment stage described later. do. In the present embodiment, by finely dispersing the Al—Co—Fe compound, it is possible to further suppress the coarsening of the crystal grains in the aging treatment process, and to maintain the crystal grain size of the crystal grains smaller. .

The Al--Co--Fe compound does not reduce the ductility of the Al alloy unlike the FeAl ₃ compound, and therefore does not hinder the diameter reduction of the alloy wire. The Al-Co-Fe compound is a compound containing at least Al, Co and Fe, and may contain other metal elements. Also, the Al--Co--Fe compound has an elongated shape in the cast ingot.

In the casting process, the cooling rate is preferably 1° C./s to 60° C./s, more preferably 20° C./s to 50° C./s.

In addition, in the present embodiment, from the viewpoint of refining the Al-Co-Fe compound and suppressing the segregation of solid solution Zr, a propelti continuous casting machine capable of casting by quenching the molten metal or a twin roll casting machine is used. billet casting or continuous casting is preferred.

(Molding process)
Subsequently, if necessary, the cast material is formed into a bar shape (so-called rough drawn wire) so that the cast material can be easily drawn. Here, for example, the cast material is machined so that the wire diameter is 5 mm to 50 mm. As machining, for example, conventionally known methods such as rolling, swaging, and drawing may be performed.

(Wire drawing process)
Subsequently, the rod-shaped cast material is subjected to cold wire drawing to be processed into a drawn wire material having a predetermined wire diameter. During this wire drawing process, the Al--Co--Fe compounds dispersed in the cast material are finely pulverized and simultaneously stretched onto a flat plate in the wire drawing direction. By dispersing the Al—Co—Fe compound more finely and densely, it is possible to more reliably suppress coarsening of crystal grains in the aging treatment step described later. The wire drawing may be performed by a conventionally known method such as drawing using a die. The workability is the ratio of the cross-sectional area of the wire drawn material to the cross-sectional area of the cast material, and indicates the rate of area reduction in the wire drawing process.

In the present embodiment, since the cast material has high ductility due to suppression of crystallization of Zr, it is possible to increase the workability of wire drawing. From the viewpoint of pulverizing the Al-Co-Fe compound more finely and dispersing it more finely in the drawn wire, the cast material is drawn so that the cross-sectional area is 0.01 times or less, and the wire diameter of the drawn wire is reduced to 2. 0 mm or less is preferable. By setting such a workability, it becomes easy to control the size of the Al--Co--Fe compound after wire drawing to 20 nm to 500 nm. In addition, when Zr is precipitated in the aging treatment step described later, the size of the Al—Zr compound can be easily controlled to 5 nm to 100 nm. Moreover, the precipitates can be more dispersed and deposited in the final alloy wire.

In addition, in this embodiment, since the cast material has high ductility, the annealing treatment (so-called intermediate annealing treatment) for alleviating working strain during wire drawing can be omitted. As a result, coarsening due to recrystallization of Al crystal grains can be further suppressed.

(Aging treatment process)
Subsequently, the drawn wire material is subjected to aging treatment. As the aging treatment, the drawn wire material may be heated, for example, in the temperature range of 270° C. to 440° C., and the treatment time may be 10 hours or longer. The aging treatment precipitates Zr, which dissolves in the Al phase in the drawn wire material, as an Al—Zr compound. The Al—Zr compound is a compound containing at least Al and Zr, and may contain other metal elements. In addition, during the aging treatment, Co that forms a solid solution in the Al alloy constituting the drawn wire may also precipitate to form an Al--Co--Fe compound.

During the aging treatment, Al crystal grains are recrystallized by heating. In this regard, in the present embodiment, since the Co compound is finely dispersed in the wire drawn material, the particles suppress the coarsening of the Al crystal grains, and the majority of the Al crystal grains are reduced to a fine size (for example, 10 μm). The following crystal grain sizes) can be maintained. From the viewpoint of obtaining various properties in a balanced manner at a higher level, the size of the Al crystal grains is kept fine so that the area occupied by the Al crystal grains with a crystal grain size of 10 μm or less is 90% or more in terms of area ratio. is preferred.

Moreover, during the aging treatment, Zr dissolved in the Al phase migrates to the grain boundaries and precipitates. At this time, in the present embodiment, since the Al crystal grains are minute and the crystal grain boundaries formed therebetween have a fine mesh structure, the distance for Zr to move from the Al phase to the crystal grain boundaries is short, and the Zr can promote precipitation at grain boundaries. Therefore, the precipitates of Zr can be finely dispersed and precipitated in the drawn wire material in a minute size (for example, 10 nm to 100 nm).

As described above, the drawn wire is subjected to aging treatment to obtain the alloy wire of the present embodiment.

<Effects of this embodiment>
According to this embodiment, one or more of the following effects can be obtained.

In this embodiment, the molten metal having the chemical composition described above is quenched at a cooling rate such that Co is crystallized while suppressing Zr from crystallizing. As a result, when the molten metal is solidified, Co is dispersed in the solidified structure as an Al--Co--Fe compound. In addition, crystallization is suppressed by dissolving Zr in the Al phase. By drawing the cast material, the Al--Co--Fe compound is pulverized into fine particles and uniformly dispersed to form a drawn wire. Then, by subjecting the drawn wire material to an aging treatment, Zr that dissolves in the Al phase is precipitated as an Al—Zr compound. In the aging treatment, Al crystal grains are recrystallized by heating along with the precipitation of Zr, but the Al-Co-Fe compound finely dispersed in the drawn wire suppresses coarsening due to recrystallization of Al crystal grains. and the Al recrystallized grains can be kept small. In addition, most of Zr is precipitated at grain boundaries between fine recrystallized Al grains and in grains in the vicinity of the grain boundaries, so that it is finely dispersed. Thus, in the present embodiment, by subjecting the cast material quenched at a predetermined cooling rate to wire drawing and aging treatment, the Al recrystallized grains are small and each of Al-Co-Fe and Al-Zr An alloy wire in which the compound is finely dispersed can be obtained.

The obtained alloy wire has the above-described chemical composition and a metal structure containing Al--Co--Fe compounds and Al--Zr compounds as Al crystal grains and dispersed particles. In the metallographic structure, many fine Al crystal grains exist, and the crystal grain boundaries formed between the crystal grains have a fine network structure, and compounds are dispersed on the crystal grain boundaries. That is, the compound is uniformly and finely dispersed in the metal structure.

An alloy wire having such a metal structure has the following properties. That is, since Fe is dispersed in the form of an Al--Co--Fe compound instead of an FeAl ₃ compound, the decrease in strength and elongation due to FeAl ₃ is suppressed. In addition, by allowing the compound to absorb Fe, the amount of Fe solid-soluted in the Al phase is small, and high electrical conductivity can be maintained. Also, since the Al—Zr compound is precipitated, high heat resistance can be obtained. Further, by finely dispersing each compound of Al--Co--Fe and Al--Zr in the alloy with fine Al crystal grains, the effect of each compound particle can be obtained at a high level and in a well-balanced manner.

Specifically, according to the alloy wire of the present embodiment, the tensile strength is 150 MPa or more, the tensile elongation is 8% or more, the electrical conductivity is 55% IACS or more, and the strength when heated at 200 ° C. for 10 years is the initial state. It is 90% or more of the strength of , and strength, elongation, conductivity and heat resistance can be obtained at a high level and in a well-balanced manner.

Also, the alloy wire preferably has a metal structure in which Al crystal grains having a grain size of 10 μm or less occupy 90% or more of the area in a cross section parallel to the longitudinal direction of the alloy wire. The larger the area ratio, the more fine Al crystal grains are present in the metal structure, and the crystal grain boundaries formed between the crystal grains have a fine network structure. In the present embodiment, by configuring the metal structure so that the area ratio of Al crystal grains of 10 μm or less is 90% or more, the mesh structure of the grain boundaries can be made finer, and the The compounds can be present more dispersedly. Thereby, strength, elongation, electrical conductivity and heat resistance can be obtained at a higher level in a well-balanced manner.

Further, the alloy wire preferably has a number of Al--Co--Fe compounds per unit area (number density) of 50/100 μm ² or more in a cross section perpendicular to the longitudinal direction. Since the Al--Co--Fe compounds are finely dispersed so as to have such a number density, the alloy wire can satisfy various characteristics of the alloy wire at a higher level.

Further, the alloy wire preferably has a number of Al—Zr compounds per unit area (number density) of 500/100 μm ² or more in a cross section perpendicular to the longitudinal direction. Since the Al--Zr compound is finely dispersed so as to have such a number density, the alloy wire can satisfy various characteristics of the alloy wire at a higher level.

Also, in the alloy wire, the size of the Al—Zr compound is preferably 5 nm or more and 100 nm or less. By reducing the size of the Al—Zr compound, the elongation of the alloy wire can be further improved, and the breakage rate during the manufacturing process can be reduced. As a result, the yield of the alloy wire can be improved.

Also, in the alloy wire, the size of the Al—Co—Fe compound is preferably 20 nm or more and 500 nm or less. When the size of the Al--Co--Fe compound falls within this range, it is possible to efficiently suppress coarsening of Al crystal grains.

Moreover, in the present embodiment, the crystallization of Zr is suppressed in the cast material, and the ductility is maintained at a high level. Therefore, in the wire drawing process, the wire can be drawn with a high workability, and the diameter of the alloy wire can be reduced while maintaining the balance of various properties at a high level. Specifically, the wire diameter can be 2 mm or less.

In addition, in the present embodiment, since the crystallization of Zr is suppressed in the cast material and the ductility is maintained at a high level, it is possible to reduce wire breakage due to working strain in the drawn wire material. In addition, since the drawn wire material has high ductility, annealing treatment for alleviating working strain can be omitted.

Moreover, in the present embodiment, the precipitates are preferably spherical. Since the precipitates are spherical, cracks at the interface between the Al phase and the precipitates can be suppressed when stress is concentrated on a part of the alloy wire due to deformation, so that the ductility of the alloy wire can be improved. can.

In addition, in the present embodiment, when the drawn wire is subjected to aging treatment, Co crystallized substances suppress recrystallization of Al crystal grains and maintain the Al crystal grains at a small particle size. Therefore, the crystal grain boundaries between the Al crystal grains have a fine network structure, so that the time required for solid-solution Zr to migrate from the Al phase to the crystal grain boundaries and precipitate can be shortened. As a result, the aging treatment can be shortened and the production efficiency of the alloy wire can be improved.

Further, when casting the molten metal, the cooling rate is preferably 1° C./s to 60° C./s, more preferably 20° C./s to 50° C./s. By quenching the molten metal under such conditions, it is possible to suppress the crystallization of Zr more reliably and crystallize Co in a more finely dispersed manner. This makes it possible to obtain a higher level of balance of properties.

Also, during wire drawing, it is preferable to draw the cast material at a workability such that the cross-sectional area of the cast material is 0.01 times or less. By drawing the wire at such a workability, the Al--Co--Fe compound crystallized in the cast material can be pulverized more finely and dispersed uniformly. As a result, in the aging treatment, the Al—Zr compound can be dispersed and precipitated more finely, and the balance of various properties can be obtained at a higher level.

EXAMPLES Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

<Production of alloy wire>
(Example 1)
In Example 1, 99.9% pure aluminum, Co, and Zr were blended so that Co, Zr, Fe, and Si had the composition shown in Table 1 below, and melted using a high-frequency melting furnace in an argon atmosphere. did. The obtained molten metal was cast in a water-cooled copper crucible to obtain a casting material having a predetermined chemical composition. The solidification rate during casting was 25° C./SEC (second). The cast material had a cylindrical shape with an outer diameter of φ30 mm and a length of 150 mm. This cast material was swaged to obtain a rough drawn wire of φ9.5 mm, and then thinned to φ0.45 mm by repeating wire drawing by drawing with a die. No intermediate heat treatment was performed during the wire drawing descent through the die. The obtained wire rod of φ0.45 mm was held in a salt bath heated and held at 300° C. for 20 hours or more to carry out aging heat treatment, and an alloy wire rod of Example 1 was produced.

(Examples 2 to 12)
In Examples 2 to 12, alloy wires were produced in the same manner as in Example 1 except that the chemical compositions of Co, Zr, Fe and Si were changed as shown in Table 1.

(Examples 13-15)
In Examples 13 to 15, alloy wires were produced in the same manner as in Example 4, except that the cooling rate was changed as shown in Table 1.

(Comparative Examples 1 to 9)
In Comparative Examples 1 to 9, alloy wires were produced in the same manner as in Example 1, except that the chemical compositions of Co, Zr, Fe and Si were changed as shown in Table 2 below.

<Evaluation method>
The metal structure, the form of compounds dispersed in the metal structure, elongation, tensile strength, electrical conductivity and heat resistance of the produced alloy wire were evaluated by the following methods.

(metal structure)
The fineness of the metal structure of the alloy wire was evaluated based on the grain size distribution of the Al crystal grains. Specifically, first, after embedding the alloy wire in the resin, a cross section perpendicular to the longitudinal direction was exposed by polishing. Next, the cross section was observed by SIM (Scanning Ion Microscope: secondary ion microscope), and the obtained SIM image was subjected to image analysis. Then, from the obtained image analysis results, the area ratios of the Al crystal grains of 10 μm or less and the Al crystal grains of more than 10 μm in the cross section were obtained, and the grain size distribution was measured. In this example, if the area ratio of Al crystal grains of 10 μm or less is 90% or more, the metal structure is evaluated as having a fine crystal structure, and is indicated by ◯. On the other hand, if it was less than 90%, it was evaluated as not having a fine crystal structure, and was marked with x.

(Form of compound)
The morphology of the compounds dispersed in the metallographic structure of the alloy wire was examined by exposing a cross section perpendicular to the longitudinal direction by polishing and observing the cross section with an STEM (scanning transmission electron microscope). For the observation, an STEM apparatus having a field emission (FE) electron beam source is used to take a high angle annular dark field image (HAADF) to capture fine particles containing Co, Fe, and Zr. Compound particles were observed. In this example, the presence or absence of Al--Co--Fe compounds and Al--Zr compounds and their number densities were measured. The number density was measured by measuring the number density for each of five different cross sections in the longitudinal direction of the alloy wire and calculating the average. In this example, the Al--Co--Fe compound was evaluated as ◯ when the number density was 50/100 μm ² or more, and was evaluated as x when it was less than 50. For the Al--Zr compound, 500/100 μm ² or more was evaluated as ◯, and less than 500 was evaluated as x.

(elongation and tensile strength)
The elongation and tensile strength of the alloy wire were measured by a tensile test of the alloy wire. In this example, elongation of 8% or more was evaluated as good elongation. Moreover, when the tensile strength was 150 MPa or more, the strength was evaluated as high.

(conductivity)
The electrical conductivity of the alloy wire was calculated by measuring the electrical resistance of the alloy wire produced at 20° C. by the DC four-terminal method. In this example, if the conductivity was 55% IACS or more, it was evaluated as having high conductivity.

(Heat-resistant)
The heat resistance of the alloy wire was evaluated by the following method to determine whether the strength was 90% or more of the strength in the initial state when heated at 200° C. for 10 years. First, the alloy wire was subjected to aging treatment by changing the heating temperature and heating time, and the tensile strength was measured from the tensile test of the wire after the aging treatment. Five wires having the same chemical composition and aging conditions were subjected to a tensile test, and the average of the test results for the five wires was adopted as the tensile strength. Next, from the values of heating temperature, heating time and tensile strength, isothermal softening curves of tensile strength at various temperatures were created. Next, from the isothermal softening curve, the time required for the tensile strength to decrease by 10% from the initial value (value of tensile strength before heating) was determined by heating. Next, the temperature and time at which the tensile strength decreases by 10% from the initial value (the time at which the tensile strength decreases by 10% from the initial value when heated at temperatures of 300 ° C., 350 ° C. and 400 ° C.) are plotted by Arrhenius, The time when the temperature in the Arrhenius plot is 200° C. (the time when the tensile strength decreases by 10%) was obtained. At this time, if the time at 200 ° C. on the Arrhenius plot is 10 years or more, it is determined to have the desired heat resistance and is judged to be acceptable (○), and if the time at 200 ° C. is less than 10 years. If any, the desired heat resistance was not obtained, and it was determined to be unacceptable (x). In this measurement, it was assumed that the softening phenomenon of 10% or less all occurred with the same activation energy.

<Evaluation results>
A SIM image of the alloy wire of Example 4 is shown in FIG. In FIG. 1, the horizontal direction corresponds to the longitudinal direction (drawing direction) of the alloy wire. According to FIG. 1, it was confirmed that many Al crystal grains were formed. It was confirmed that most of the Al grains were equiaxed grains with a small aspect ratio. Further, when the grain size distribution of the SIM image shown in FIG. It was confirmed that the occupied area ratio was as small as 3.3%, and most of them were fine crystal grains with a size of less than 10 µm.

A STEM image of the alloy wire of Example 4 is shown in FIG. According to FIG. 2, dispersion of round-shaped particles (white) was confirmed. The size of the round particles is in the range of several tens to several hundreds of nanometers, and they are mainly distributed on grain boundaries. Finer grains than these round grains also exist in the metallographic structure of FIG. FIG. 3 shows a metallographic structure in which a part of the STEM image of FIG. 2 is enlarged. According to FIG. 3, it was confirmed that particles with a size of several tens of μm were dispersed both at the grain boundaries and inside the grains. It was also found that the shape of the particles observed in FIG. 3 was irregular, such as dot-like, rod-like, and band-like.

In FIG. 2, when the chemical composition of the dispersed particles was measured by energy dispersive analysis (EDS), Co and Fe were detected in addition to Al from the round particles. Quantitative analysis of the EDS spectrum revealed that the Fe content in the particles was less than the Co content. From this result, it was suggested that the round particles in FIG. 2 are AlCo compounds represented by the Al ₉ Co ₇ phase, and may be Al—Co—Fe compounds in which part of Co is replaced with Fe. . Also, no Al--Fe compound phase containing only Fe without Co, such as an Al ₃ Fe compound, was confirmed.

Further, when EDS analysis was performed on the fine irregular-shaped particles confirmed in FIG. 3, Zr was detected in addition to Al, but Co and Fe were not detected. From this result, it was found that these amorphous fine particles were Al—Zr compounds represented by Al ₃ Zr.

In addition, in the alloy wire of Example 4, the number of round-shaped Al—Co—Fe compound particles was 210 per 100 μm ² on average at five locations. In addition, the average number of irregular shaped Al—Zr compound particles was 2,800 per 100 μm ² at five locations.

In addition, as shown in Table 1, the alloy wire of Example 4 was confirmed to have well-balanced properties at high levels. Specifically, it was confirmed that the elongation was 8%, the tensile strength was 179 MPa, and the electrical conductivity was 56% IACS. In addition, even when the alloy wire of Example 4 is heated at 200 ° C. for 10 years, the decrease in strength due to heating is 10% or less from the initial state, and 90% or more of the strength in the initial state is maintained. It was confirmed that it can be done and that it has high heat resistance. It is presumed that this is because the Al recrystallized grains are small and the compounds of Al--Co--Fe and Al--Zr are finely dispersed in the metallographic structure of the alloy wire.

In Examples 1 to 3 and 5 to 12, the area occupied by Al crystal grains with a crystal grain size of 10 μm or less was 90% or more, and it was confirmed that a fine crystal structure was formed. Specifically, the areas occupied by coarse crystal grains having a grain size of more than 10 μm were less than 10% in terms of area ratio. Further, when the STEM dark field image was examined for each example, it was confirmed that Al--Co--Fe compounds and Al--Zr compounds were dispersed in all samples. In addition, as in Example 4, it was confirmed that various properties were maintained at a high level and in a well-balanced manner.

Examples 13 to 15 show the results of alloys with the same chemical composition as in Example 4, where the solidification rate during casting was changed from 25°C/SEC (sec) to 8, 12, and 20°C/SEC. The tensile strength gradually decreases as the solidification rate slows down. On the other hand, the electrical conductivity tends to increase as the solidification rate slows down. This is because when the solidification rate increases, the crystallization of Zr during casting is suppressed, the amount of supersaturated solid solution of Zr increases, and the precipitation of Al—Zr compounds during aging treatment is promoted, resulting in an increase in tensile strength. it is conceivable that.

On the other hand, in the alloy wire of Comparative Example 1, as shown in FIGS. 4 to 6, it was confirmed that the metal structure of Example 1 was not formed. 4 is a SIM (secondary ion microscope) image of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire of Comparative Example 1. FIG. FIG. 5 is a dark-field image of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire of Comparative Example 1, taken by STEM (scanning electron microscope). FIG. 6 is an enlarged view of FIG.

According to FIG. 4, in the alloy wire of Comparative Example 1, most of the Al crystal grains are elongated in the longitudinal direction and have a large aspect ratio. In a part of FIG. 4, coarse crystal grains exceeding 10 μm in the longitudinal direction are recognized. These longitudinally elongated grains are considered to be formed by the easy movement of grain boundaries in the longitudinal direction at the stage of recrystallization during the aging heat treatment.

In addition, when the grain size distribution of the SIM image shown in FIG. 4 was measured by image analysis processing, coarse grains with a length exceeding 10 μm accounted for 44.7% of the entire observation area in terms of area ratio. , it was confirmed that Al crystal grains tend to coarsen as compared with Example 1.

Further, according to the STEM image of Comparative Example 1 shown in FIG. 5, there are no round particles (Al—Co—Fe compound) as in Example 1, and fine particles of 100 nm or less are present at the grain boundaries. Dispersion is observed. According to FIG. 6, similarly to FIG. 3 of Example 1, it can be seen that irregularly shaped particles with a size of about several tens to 100 μm are dispersed both at the grain boundaries and inside the grains.

EDS analysis of the irregularly shaped particles in FIG. 6 detected Zr in addition to Al, but did not detect Co or Fe. From this result, it was found that these irregularly shaped particles were Al--Zr compounds represented by Al ₃ Zr. In addition, it was also confirmed that there were some coarser particles with a size of about several hundred μm, although only a few, in which only Fe was detected in addition to Al. It was presumed that the coarse particles containing only Fe were highly likely to be Al—Fe compounds such as Al ₃ Fe. In other words, in the alloy wire of Comparative Example 1, the compounds dispersed in the metal structure are presumed to be Al--Zr compounds and a small number of Al--Fe compounds. The number density of the Al—Zr compound was 3,300 per 100 μm ² on average at five locations.

Moreover, the alloy wire of Comparative Example 1 had an elongation of 4% and a tensile strength of 149 MPa, and it was confirmed that desired mechanical properties could not be obtained. It is presumed that this is because no Al--Co--Fe compound is formed because Co is not blended. It should be noted that the heat resistance of Comparative Example 1 was determined to be acceptable.

In Comparative Examples 2 and 3, when the SIM image was subjected to image analysis processing to measure the grain size distribution, it was confirmed that coarse grains with a length of more than 10 μm accounted for more than 20% of the entire observation area in terms of area ratio. was done. In Comparative Example 2, since Zr was not added, no Al—Zr compound was formed. Therefore, although the elongation is high, it was confirmed that the tensile strength is remarkably low. On the other hand, in Comparative Example 3, although Zr was added, it was as small as 0.1% by mass, so formation of an Al—Zr compound was not confirmed. Therefore, it was confirmed that desired mechanical properties could not be obtained similarly to Comparative Example 2. In addition, in the alloy wires of Comparative Examples 2 and 3, the time required for the strength to decrease to less than 90% of the strength in the initial state when heated at 200°C (the time required for the decrease in strength due to heating to reach 10% or more). was less than 10 years, and the heat resistance was confirmed to be unsatisfactory. It is believed that this is because the Al--Zr compound was not formed, resulting in lower heat resistance.

In Comparative Examples 4 to 9, although Al crystal grains with a grain size of 10 μm or less are present, it was confirmed that the area ratio was about 80% and less than 90%. Also, although an Al--Co--Fe compound and an Al--Zr compound were formed, it was confirmed that the properties were not well-balanced because it was desired that the content of Co, Zr, Fe and Si be moderate. The heat resistance in each example was determined to be acceptable.

<Preferred embodiment of the present invention>
Preferred embodiments of the present invention are additionally described below.

[Appendix 1]
According to one aspect of the invention,
A wire rod made of an aluminum alloy,
The aluminum alloy is
Co: 0.1 to 1.0% by mass, Zr: 0.2 to 0.5% by mass, Fe: 0.02 to 0.09% by mass, Si: 0.02 to 0.09% by mass, Mg: 0 to 0.2% by mass, Ti: 0 to 0.10% by mass, B: 0 to 0.03% by mass, Cu: 0 to 1.00% by mass, Ag: 0 to 0.50% by mass, Au: 0 to 0.50% by mass, Mn: 0 to 1.00% by mass, Cr: 0 to 1.00% by mass, Hf: 0 to 0.50% by mass, V: 0 to 0.50% by mass, Sc: 0 to 0.50% by mass, Ni: 0 to 0.50% by mass, the balance: having a chemical composition consisting of Al and inevitable impurities, and
Having a metal structure containing Al crystal grains and Al-Co-Fe compounds and Al-Zr compounds,
Tensile strength of 150 MPa or more,
Conductivity is 55% IACS or more,
The strength when heated at 200 ° C. for 10 years is 90% or more of the strength in the initial state,
An aluminum alloy wire is provided.

[Appendix 2]
In the aluminum alloy wire rod of Supplementary Note 1, preferably,
In the metallographic structure, the area occupied by the Al crystal grains having a grain size of 10 μm or less is 90% or more in area ratio.

[Appendix 3]
In the aluminum alloy wire of Supplementary Note 1 or 2, preferably,
In a cross section perpendicular to the longitudinal direction, the number of Al—Zr compounds per unit area is 500/100 μm ² or more.

[Appendix 4]
In the aluminum alloy wire according to any one of Appendices 1 to 3, preferably
In a cross section perpendicular to the longitudinal direction, the number of Al--Co--Fe compounds per unit area is 50/100 μm ² or more.

[Appendix 5]
In the aluminum alloy wire according to any one of Appendices 1 to 4, preferably
The size of the Al-Co-Fe compound is 20 nm or more and 500 nm or less.

[Appendix 6]
In the aluminum alloy wire according to any one of Appendices 1 to 5, preferably
The size of the Al—Zr compound is 5 nm or more and 100 nm or less.

[Appendix 7]
In the aluminum alloy wire according to any one of Appendices 1 to 6, preferably
The wire diameter is 2.0 mm or less.

[Appendix 8]
In the aluminum alloy wire according to any one of Appendices 1 to 7, preferably
The Al-Co-Fe compound and the Al-Zr compound have a spherical shape.

[Appendix 9]
According to another aspect of the invention,
A method for manufacturing a wire rod made of an aluminum alloy,
Co: 0.1 to 1.0% by mass, Zr: 0.2 to 0.5% by mass, Fe: 0.02 to 0.09% by mass, Si: 0.02 to 0.09% by mass, Mg: 0 to 0.2% by mass, Ti: 0 to 0.10% by mass, B: 0 to 0.03% by mass, Cu: 0 to 1.00% by mass, Ag: 0 to 0.50% by mass, Au: 0 to 0.50% by mass, Mn: 0 to 1.00% by mass, Cr: 0 to 1.00% by mass, Hf: 0 to 0.50% by mass, V: 0 to 0.50% by mass, Sc: A preparation step of preparing a molten metal consisting of 0 to 0.50% by mass, Ni: 0 to 0.50% by mass, and the balance: Al and inevitable impurities;
a casting step of forming a casting material containing an Al—Co—Fe compound by quenching and casting the molten metal at a cooling rate that causes Co to crystallize while suppressing the crystallization of Zr;
A wire drawing step of drawing the cast material to form a drawn wire material;
an aging treatment step of subjecting the drawn wire material to aging treatment, and precipitating Zr dissolved in the Al phase as an Al—Zr compound;
The aluminum alloy has the chemical composition and a metal structure containing Al crystal grains, an Al—Co—Fe compound, and an Al—Zr compound, and the wire has a tensile strength of 150 MPa or more and an electrical conductivity of 55% IACS. As described above, the strength when heated at 200 ° C. for 10 years is configured to be 90% or more of the strength in the initial state,
A method for manufacturing an aluminum alloy wire is provided.

[Appendix 10]
In the method for producing an aluminum alloy wire according to Supplementary Note 9, preferably
The maximum recrystallized grain size of Al crystal grains in the metal structure is 10 μm or less.

[Appendix 11]
In the method for producing an aluminum alloy wire according to Supplementary Note 9 or 10, preferably
In the casting step, the cooling rate is set to 1° C./s or more and 60° C./s or less.

[Appendix 12]
In the method for producing an aluminum alloy wire according to any one of Appendices 9 to 11, preferably
In the wire drawing step, the cast material is drawn at a workability such that the cross-sectional area is 0.01 times or less.

[Appendix 13]
In the method for producing an aluminum alloy wire according to any one of Appendices 9 to 12, preferably,
In the wire drawing step, the wire diameter of the wire drawn material is set to 2.0 mm or less.

Claims (10)

A wire rod made of an aluminum alloy,
The aluminum alloy is
Co: 0.1 to 1.0% by mass, Zr: 0.2 to 0.5% by mass, Fe: 0.02 to 0.09% by mass, Si: 0.02 to 0.09% by mass, balance: Having a chemical composition consisting of Al and inevitable impurities,
And,
Having a metal structure containing Al crystal grains and Al-Co-Fe compounds and Al-Zr compounds,
Tensile strength of 150 MPa or more,
Conductivity is 55% IACS or more,
Arrhenius plotted the time for the tensile strength to decrease by 10% from the initial value when heated at temperatures of 300 ° C., 350 ° C. and 400 ° C., and the time when heated at 200 ° C. for 10 years obtained from the Arrhenius plot. The tensile strength is 90% or more of the tensile strength in the initial state ,
In the metal structure, in a cross section along the longitudinal direction, the area occupied by the Al crystal grains having a crystal grain size of 10 μm or less, which is the maximum grain size, is 90% or more in terms of area ratio.
Aluminum alloy wire. In a cross section perpendicular to the longitudinal direction, the number of Al—Zr compounds per unit area is 500/100 μm ² or more,
The aluminum alloy wire according to claim 1 . In a cross section perpendicular to the longitudinal direction, the number of Al-Co-Fe compounds per unit area is 50/100 μm ² or more,
The aluminum alloy wire according to claim 1 or 2 . The size of the Al-Co-Fe compound is 20 nm or more and 500 nm or less,
The aluminum alloy wire according to any one of claims 1 to 3 . The Al—Zr compound has a size of 5 nm or more and 100 nm or less,
The aluminum alloy wire according to any one of claims 1-4 . The wire diameter is 2.0 mm or less,
The aluminum alloy wire according to any one of claims 1-5 . The Al-Co-Fe compound has a spherical or spheroidal shape,
The Al—Zr compound has a spherical shape or irregular shape,
The aluminum alloy wire according to any one of claims 1-6 . A method for manufacturing a wire rod made of an aluminum alloy,
Co: 0.1 to 1.0% by mass, Zr: 0.2 to 0.5% by mass, Fe: 0.02 to 0.09% by mass, Si: 0.02 to 0.09% by mass, balance: A preparation step of preparing a molten metal containing Al and unavoidable impurities;
a casting step of forming a cast material by rapidly cooling the molten metal at a cooling rate of 1° C./s or more and 60° C./s or less;
A wire drawing step of drawing the cast material to form a drawn wire material;
an aging treatment step of subjecting the drawn wire material to aging treatment at 270° C. or higher and 440° C. or lower for 10 hours or longer;
The aluminum alloy has a metal structure containing Al crystal grains and an Al-Co-Fe compound and an Al-Zr compound, and the tensile strength of the wire is 150 MPa or more, the electrical conductivity is 55% IACS or more, 300 ° C., Arrhenius plot the time for the tensile strength to decrease by 10% from the initial value when heated at temperatures of 350 ° C. and 400 ° C., and the tensile strength when heated at 200 ° C. for 10 years obtained from the Arrhenius plot. Configured to be 90% or more of the tensile strength in the initial state,
In the metal structure, in a cross section along the longitudinal direction, the area occupied by the Al crystal grains having a crystal grain size of 10 μm or less, which is the maximum grain size, is configured so that the area ratio is 90% or more .
A method for producing an aluminum alloy wire. In the wire drawing step, the cast material is drawn at a workability such that the cross-sectional area is 0.01 times or less,
The method for producing an aluminum alloy wire according to claim 8 . In the wire drawing step, the wire diameter of the wire drawn material is set to 2.0 mm or less,
The method for producing an aluminum alloy wire according to claim 8 or 9 .

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