JP2021066927A - Aluminum alloy foil - Google Patents

Abstract

To provide aluminum alloy foil having high elongation characteristics.SOLUTION: Aluminum alloy foil is provided that has a composition containing 1.2 mass% to 1.6 mass% of Fe, 0.05 mass% to 0.15 mass% of Si, and 0.005 mass% to 0.1 mass% of Cu, Mn being restricted to 0.01 mass% or less, and the remainder composed of Al and other inevitable impurities. An average crystal grain size of the aluminum alloy foil is 20 to 30 μm, maximum crystal grain size/average crystal grain size is equal to or less than 3.0, Cube orientation density is 10 or more, Cu orientation density is 20 or less, and R orientation density is 15 or less.SELECTED DRAWING: None

Description

The present invention relates to an aluminum alloy foil having excellent moldability.

Aluminum alloy foils used for packaging materials such as foods and lithium-ion batteries are required to have high elongation because they are formed by being subjected to large deformation by press molding or the like. Conventionally, as a material having high elongation, for example, a soft foil of a JIS A1000 series alloy called 1N30 or the like or a JIS A8000 series alloy such as 8079 or 8021 has been used.
Aluminum alloy foil is not deformed in one direction, but is often overhanged and deformed in multiple directions. Therefore, regarding the elongation characteristics, in addition to the elongation in the rolling direction, which is generally used as the elongation value. In addition, it is required that the elongation at 45 ° and 90 ° with respect to the rolling direction is high.

In response to such a demand, it has been conventionally proposed to control the crystal grains in the alloy in order to realize an aluminum alloy foil having high elongation.
For example, Patent Document 1 attempts to obtain high moldability by defining an average crystal grain of 7 to 20 μm.
Further, Patent Document 2 attempts to obtain high moldability by defining a very fine crystal particle size of 12 μm or less.
Further, Patent Document 3 defines a fine crystal grain structure having an average crystal grain size of 7.0 to 12.0 μm.

International Publication No. 2013/1686606 Japanese Unexamined Patent Publication No. 2014-47372 Japanese Unexamined Patent Publication No. 2018-115376

However, in the above-mentioned Patent Documents 1 to 3, the elongation characteristics are not sufficient, and the balance between strength and elongation is not good.

The present invention has been made against the background of the above circumstances, and one of the objects of the present invention is to provide an aluminum alloy foil having good processability and high moldability.

That is, in the first form of the aluminum alloy foil of the present invention, Fe: 1.2% by mass or more and 1.6% by mass or less, Si: 0.05% by mass or more and 0.15% by mass or less, Cu: 0. An aluminum alloy foil containing .005% by mass or more and 0.1% by mass or less, restricted to Mn: 0.01% by mass or less, and having a composition in which the balance is composed of Al and other unavoidable impurities. The average crystal grain size is 20 to 30 μm, the maximum crystal grain size / average crystal grain size ≤ 3.0, the Cube orientation density is 10 or more, the Cu orientation density is 20 or less, and the R orientation density is 15 or less. It is characterized by being.

The invention of the aluminum alloy foil of the second aspect is the grain boundary (HAGB) having an orientation difference of 15 ° or more and the orientation difference in the crystal orientation analysis per unit area by backscattered electron diffraction (EBSD) in the above embodiment. It is characterized in that the ratio of the lengths of small tilt angle grain boundaries (LAGB) of 2 ° or more and less than 15 ° is “HAGB length / LAGB length> 2.0”.

In the invention of the aluminum alloy foil of the third embodiment, in the above-described embodiment, the number density of Al—Fe-based intermetallic compounds having a particle diameter (corresponding to a circle) of 1.0 to 3.0 μm is 6.0 × 10 ³ pieces / mm ² or less, and the same number density of less than the particle diameter (circle equivalent diameter) 0.1 [mu] m or more 1.0μm is characterized in that it is 1.0 × 10 ⁴ cells / mm ² or more.

The method for producing an aluminum alloy foil of the present invention is the method for producing an aluminum alloy foil according to any one of the above-mentioned embodiments.
Fe: 1.2% by mass or more and 1.6% by mass or less, Si: 0.05% by mass or more and 0.15% by mass or less, Cu: 0.005% by mass or more and 0.1% by mass or less, Mn: The ingot of an aluminum alloy having a composition of Al and other unavoidable impurities with the balance regulated to 0.01% by mass or less is subjected to a homogenization treatment of holding at 480 to 540 ° C. for 6 hours or more, and then rolled after the homogenization treatment. Hot rolling is performed so that the finished temperature is 230 ° C. or higher and lower than 300 ° C., and in the middle of cold rolling, intermediate annealing is performed at a temperature of 300 to 400 ° C. for 3 hours or more, and the final intermediate annealing is performed. After that, the final cold rolling ratio to the final thickness is 90% or more and less than 95%.

Hereinafter, the contents specified in the present invention will be described.
-Fe: 1.2% by mass or more and 1.8% by mass or less Fe crystallizes as an Al-Fe intermetallic compound during casting, and if the size is large, it becomes a recrystallized site during annealing to make the recrystallized grains fine. It has the effect of becoming. If it is less than 1.2% by mass, the distribution density of the coarse intermetallic compound becomes low, the effect of its miniaturization is low, and the final crystal grain size distribution becomes non-uniform. If it exceeds 1.8% by mass, the effect of grain refinement is saturated or reduced, and the size of the Al—Fe intermetallic compound produced during casting becomes very large, so that the foil has elongation, formability, and rollability. Decreases. A particularly preferable range is 1.2% by mass at the lower limit and 1.6% by mass at the upper limit.

-Si: 0.05% by mass or more and 0.15% by mass or less Si forms an intermetallic compound together with Fe. If it exceeds 0.15% by mass, there is a concern that the rollability and elongation characteristics may be deteriorated due to the formation of coarse intermetallic compounds, and the uniformity of the recrystallized grain size after final annealing may be deteriorated. If it is less than 0.05% by mass, the precipitation of Fe is suppressed, the amount of solid solution Fe increases, and the ratio of continuous recrystallization increases during intermediate annealing and final annealing. As the proportion of continuous recrystallization increases, the Cu orientation develops even after recrystallization, and the uniformity of grain size also decreases. For the above reasons, the lower limit of Si is preferably 0.07% and the upper limit is preferably 0.13%.

-Cu: 0.005% by mass or more and 0.1% by mass or less Cu is an element that increases the strength of aluminum foil and lowers its elongation. On the other hand, it has the effect of suppressing excessive work softening during cold rolling, which has been reported for Al—Fe alloys. If it is less than 0.005% by mass, the effect of suppressing work softening is low, and if it exceeds 0.1% by mass, the material becomes hard and the elongation and moldability are clearly lowered. Preferably, the lower limit is 0.005% and the upper limit is 0.005% or less.

-Mn: 0.01% by mass or less Mn dissolves in the aluminum matrix or forms a very fine compound, and has a function of suppressing recrystallization of aluminum. If the amount is small, it can be expected to suppress work softening as in Cu, but if the amount added is large, recrystallization during intermediate annealing and final annealing will be delayed, making it difficult to obtain fine and uniform crystal grains. It causes excessive development of Cu orientation and R orientation. Therefore, it is regulated to 0.01% or less. More preferably, the upper limit is 0.005%.

・ Average crystal grain size 20 to 30 μm
Since the crystal grains of the soft aluminum foil become finer, it is possible to suppress rough skin on the foil surface when it is deformed, and high elongation and high moldability associated therewith can be expected. However, if the crystal grains become too fine, the material becomes hard, and the n value (work hardening index) decreases, so that there is a concern that the elongation decreases. In addition, fine recrystallized grains in Al—Fe-based alloys are often obtained by continuous recrystallization, and in that case, the Cu orientation density becomes very high even after final annealing, and the grain size also becomes non-uniform. There is a concern that the sex will deteriorate. If the average crystal grain size is less than 20 μm, there is a concern that the above-mentioned crystal grain refinement may have an adverse effect. If it exceeds 30 μm, the surface of the foil becomes rough during molding, which causes a decrease in moldability.
The n value is not limited, but 0.23 or more is desirable.

・ Maximum crystal grain size / average crystal grain size ≤ 3.0
Even if the average crystal grain size is the same, if the grain size distribution of the crystal grains is non-uniform, local deformation is likely to occur, and the elongation and moldability of the foil are lowered. Therefore, high moldability can be obtained by setting not only the average crystal grain but also the maximum particle size / average particle size ≤ 3.0.

-As the texture, the Cube orientation density is 10 or more, the Cu orientation density is 20 or less, and the R orientation density is 15 or less. The texture has a great influence on the elongation of the foil. When the Cube orientation density is less than 10, the Cu orientation density exceeds 20, and the R orientation density also exceeds 15, significant anisotropy occurs in the elongation of the foil, and the elongation in the 45 ° direction with respect to the rolling direction increases. On the contrary, the elongation value in the 0 and 90 ° directions decreases. If anisotropy occurs in elongation, uniform deformation cannot be achieved during molding, and moldability deteriorates. Therefore, by keeping the Cube azimuth density of 10 or more, the Cu azimuth density of 20 or less, and the R azimuth density of 15 or less, the balance of elongation in three directions can be maintained.

Aggregation is a factor that is influenced by various factors during manufacturing. Among them, in order to achieve the texture of the product of the present invention, (1) the Cu orientation should not be excessively developed immediately before the final annealing, that is, after the final cold rolling, and (2) discontinuous recrystallization during recrystallization during the final annealing. It is especially important to increase the proportion of. For example, one of the factors satisfying (1) is not to make the final cold rolling ratio from intermediate annealing to the final thickness too high. Basically, the higher the cold rolling ratio, the higher the Cu orientation density. Regarding (2), it is desirable to reduce the solid solution amount of Fe in the aluminum matrix, and to set the final cold rolling ratio to some extent, which is contrary to (1). The recrystallization behavior is roughly divided into continuous recrystallization and discontinuous recrystallization, but if the ratio of continuous recrystallization is large, the texture after cold rolling will be maintained considerably even after final annealing. As a result, the Cu orientation density tends to be high and the Cube orientation density tends to be low. To reduce the solid solution amount of Fe as much as possible, it can be achieved by optimizing the conditions of homogenization treatment and intermediate annealing and promoting the precipitation of Fe.

・ "HAGB (large grain boundary) length / LAGB (small angle grain boundary) length>2.0"
Although not limited to Al—Fe alloys, the ratio of the length of LAGB to HAGB to the total grain boundaries changes depending on the recrystallization behavior during annealing. A large proportion of LAGB after final annealing is often seen when the proportion of continuous recrystallization is high, and even if the average grain is fine, it is local when HAGB length / LAGB length ≤ 2.0. Deformation is likely to occur and the elongation is reduced. It is desirable that HAGB length / LAGB length> 2.0, which can be expected to improve moldability.
For example, in Patent Document 2, the crystal grain boundary is defined as a grain boundary having an orientation difference of 5 ° or more obtained by EBSD. If it is 5 ° or more, LAGB and HAGB are mixed, and it is unclear whether the recrystallized grains surrounded by HAGB are really fine.

In order to achieve the ratio of HAGB (large grain boundary) length / LAGB (small angle grain boundary) length, it is particularly important to increase the ratio of discontinuous recrystallization in recrystallization at the time of final annealing. That is, it is necessary to sufficiently precipitate Fe by homogenization treatment or intermediate annealing to reduce the solid solution amount of Fe in the aluminum matrix and set a high final cold rolling ratio to some extent.

-Density of Al-Fe intermetallic compounds with a particle size of 1.0 μm or more and 3.0 μm or less: 6.0 × 10 ³ pieces / mm ² or less 1.0 μm or more generally acts as a nucleation site during recrystallization. It is said that the particle size is such that fine recrystallized grains can be easily obtained at the time of annealing due to the high density distribution of such intermetallic compounds. If the particle size is less than 1.0 μm, it is difficult to effectively work as a nucleation site during recrystallization, and if it exceeds 3.0 μm, pinholes are likely to occur and elongation is likely to decrease. However, when such a coarse compound is present at a high density, it also serves as a starting point of pinholes during molding and causes deterioration of moldability. Therefore, the distribution density is preferably 6.0 × 10 ³ pieces / mm ² or less.
However, when the particle density of the above-mentioned intermetallic compound becomes extremely low, it leads to coarsening of crystal grains. Therefore, it ^{is desirable that the particle density is 2.0 × 10 3} pieces / mm ² or more.
The particle size is indicated by a circle-equivalent diameter.

The density of the compound is mainly determined by the amount of Si and Fe added and the conditions of the homogenization treatment. It is important to perform the homogenization treatment under appropriate conditions while selecting the appropriate amount of Fe and Si. If the amount of Fe is small, the density decreases, and if it is too large, the upper limit density is exceeded. Further, when the amount of Fe is extremely large, the compound is significantly coarsened, and the risk of producing a coarse compound greatly exceeding 3.0 μm is increased. Further, when the amount of Si is small, the density of fine compounds of 1.0 μm or less increases, and when the amount of Si is too large, the compound becomes coarse. When the homogenization treatment temperature is low, the compound density of 1.0 μm or more tends to be low, and conversely, when the temperature is high, it increases.

-Density of Al-Fe intermetallic compounds with a particle size of 0.1 μm or more and less than 1.0 μm: 1.0 × 10 ⁴ pieces / mm ² or more Although it is generally said that it is difficult to become a core of recrystallization, Results suggesting that it has a great influence on the refinement and recrystallization behavior of crystal grains have been obtained. Although the detailed mechanism is not yet clear, the HAGB length / LAGB length after final annealing is due to the presence of some fine compounds of less than 1.0 μm in addition to the coarse intermetallic compounds with a particle size of 1.0 to 3.0 μm. It has been confirmed that the decrease in the amount of particles is suppressed. It is also possible that the fragmentation of crystal grains during cold rolling (Grain subdivision mechanism) is promoted. Therefore, the density of the Al—Fe-based intermetallic compound in the particle size range is preferably in the above range.

For the above density, the amount of Si and Fe added and the conditions of the homogenization treatment are important. If the amount of Fe or Si is too large, the density of fine compounds will decrease. The same applies if the homogenization treatment temperature is too high.

-Homogenization treatment: Hold at 480 to 540 ° C for 6 hours or more The obtained ingot is subjected to a homogenization treatment for holding at 480 to 540 ° C for 6 hours or more. At 480 ° C or lower, Fe precipitation is small and the growth of intermetallic compounds is insufficient, while at 540 ° C or higher, the growth of intermetallic compounds is remarkable, and the density of fine intermetallic compounds with a particle size of 0.1 μm or more and less than 1 μm is high. It will drop significantly. In such a homogenization treatment at around 500 ° C., a long-time heat treatment is required to precipitate fine intermetallic compounds at high density, and it is necessary to secure at least 6 hours or more. If it is less than 6 hours, the precipitation is not sufficient and the density of fine intermetallic compounds decreases.

-Hot rolling: Finishing temperature 230 ° C or higher and lower than 300 ° C In hot rolling, it is desirable to set the finished temperature to less than 300 ° C and suppress recrystallization. By setting the hot-rolled finished temperature to 300 ° C. or lower, the hot-rolled plate has a uniform fiber structure. By suppressing recrystallization after hot rolling in this way, the amount of strain accumulated up to the subsequent intermediate annealing plate thickness increases, and a recrystallized grain structure with a uniform particle size can be obtained during intermediate annealing. .. This also leads to the uniformity of the final crystal grain size. If the temperature exceeds 300 ° C, recrystallization occurs in a part of the hot-rolled plate, the fiber structure and the recrystallized grain structure are mixed, and the recrystallized grain size at the time of intermediate annealing becomes non-uniform, which is the final as it is. This leads to non-uniform crystal grain size. Since the temperature during hot rolling is extremely low for finishing at less than 230 ° C., there is a concern that cracks may occur on the side of the plate and the productivity may be significantly reduced.

・ Intermediate annealing: 300 ° C to 400 ° C
In the intermediate annealing, the hardened material is softened by repeating cold rolling to restore the rollability, and the precipitation of Fe is promoted to reduce the amount of solid solution Fe. If the temperature is lower than 300 ° C, recrystallization is not completed and there is a risk that the crystal grain structure becomes non-uniform, and if the temperature is higher than 400 ° C, the recrystallized grains become coarse and the final grain size becomes large. Further, at high temperatures, the amount of Fe deposited decreases and the amount of solid solution Fe increases. When the amount of solid solution Fe is large, discontinuous recrystallization at the time of final annealing is suppressed, and the ratio of small tilt angle grain boundaries increases. Therefore, the intermediate annealing temperature is preferably less than 380 ° C., and the holding time of intermediate annealing is preferably 3 hours or more. If it is less than 3 hours, recrystallization may be incomplete and Fe precipitation may be insufficient. There is no particular upper limit, but considering productivity, 15 hours or less is desirable.

-Final cold rolling rate: 90% or more and less than 95% The higher the final cold rolling rate from after intermediate annealing to the final thickness, the greater the amount of strain accumulated in the material and the finer the recrystallized grains after final annealing. At the same time, the development of Cu orientation becomes remarkable. On the contrary, if the final cold rolling ratio is too low, it causes coarsening and non-uniformity of recrystallized grains. Specifically, it is desirable to control the final cold rolling ratio to 90 to 95%, and if it is less than 90%, the amount of accumulated strain decreases, which leads to coarsening and non-uniformity of the crystal grain size after final annealing. In that case, the rate of recrystallization also increases, LAGB with an orientation difference of less than 15 ° increases, and HAGB length / LAGB length decreases. On the other hand, if it exceeds 95%, the development of Cu orientation in cold rolling becomes remarkable, and the Cu orientation density becomes remarkable even after the final annealing.

According to the present invention, an aluminum alloy foil having high elongation characteristics can be obtained.

It is a figure which shows the planar shape of the square punch used in the limit forming height test in the Example of this invention.

A method for producing an aluminum alloy foil according to an embodiment of the present invention will be described.
As an aluminum alloy, Fe: 1.2% by mass or more and 1.6% by mass or less, Si: 0.05% by mass or more and 0.15% by mass or less, Cu: 0.005% by mass or more and 0.1% by mass or less. Then, Mn: was regulated to 0.01% by mass or less, and the balance was adjusted to a composition consisting of Al and other unavoidable impurities to produce an aluminum alloy ingot. The method for producing the ingot is not particularly limited, and it can be produced by a conventional method such as semi-continuous casting. The obtained ingot is homogenized by holding it at 480 to 540 ° C. for 6 hours or more.

After the homogenization treatment, hot rolling is performed, and the rolling finish temperature is set to 230 ° C. or higher and lower than 300 ° C. After that, cold rolling is performed, and intermediate annealing is performed one or more times during the cold rolling. In the intermediate annealing, the temperature is set to 300 ° C to 400 ° C. The intermediate annealing time is preferably 3 hours or more. If it is less than 3 hours, the softening of the material may be insufficient when the annealing temperature is low. It should be noted that long-time annealing of more than 10 hours is economically unfavorable, and therefore 10 hours or less is preferable.
The cold rolling after the final intermediate annealing corresponds to the final cold rolling, and the final cold rolling ratio at that time is set to less than 90 to 95%. The final thickness of the foil is not particularly limited, but can be, for example, 10 μm to 40 μm.

The obtained aluminum alloy foil has an average crystal grain size of 20 to 30 μm, and a maximum crystal grain size / average crystal grain size ≦ 3.0.
The aluminum alloy foil preferably has a Cube density of 10 or more, a Cu directional density of 20 or less, and an R directional density of 15 or less.
Aluminum foil has an excellent balance between excellent elongation characteristics and strength. For example, the elongation in each direction of 0 °, 45 °, 90 ° is 25% or more, 0 °, 45 °, 90 with respect to the rolling direction. The strength in each direction of ° is 90 MPa or more, and the balance between elongation and strength in the three directions can be better maintained.

In the aluminum alloy foil, it is desirable that the density of the intermetallic compound satisfies the following regulations.
-The number density of Al-Fe intermetallic compounds having a particle size of 1.0 to 3.0 μm is 6.0 × 10 ³ pieces / mm ² or less, and the same number density of particle size 0.1 μm or more and less than 1.0 μm. Is 1.0 x 10 ⁴ pieces / mm ² or more

The aluminum alloy foil can be deformed by press molding or the like, and can be suitably used as a packaging material for foods and lithium ion batteries. In the present invention, the use of the aluminum alloy foil is not limited to the above, and the aluminum alloy foil can be used for an appropriate purpose.

An ingot of an aluminum alloy having the composition shown in Table 1 (the balance is Al and other unavoidable impurities) was produced by a semi-continuous casting method. Then, the obtained ingot was subjected to the production conditions shown in Table 1 (homogenization treatment conditions, hot rolling finish temperature, plate thickness at intermediate annealing, intermediate annealing conditions, final cold rolling ratio). An aluminum alloy foil was produced by homogenization treatment, hot rolling, cold rolling, intermediate annealing, and cold rolling again.
The thickness of the foil was 30 μm.

The following measurements and evaluations were performed on the obtained aluminum alloy foil.
-Tensile strength and elongation were both measured by a tensile test. The tensile test conforms to JIS Z2241 and is a universal tensile tester (Shimadzu Corporation) by collecting a JIS No. 5 test piece from a sample so that elongation in each direction of 0, 45, 90 ° with respect to the rolling direction can be measured. The test was carried out with AGS-X 10 kN) at a tensile speed of 2 mm / min. The calculation of the growth rate is as follows. First, before the test, two lines are marked in the center of the length of the test piece in the vertical direction of the test piece at intervals of 50 mm, which is the reference point distance. After the test, the fracture surface of the aluminum alloy foil is matched to measure the distance between marks, and the elongation amount (mm) obtained by subtracting the gauge point distance (50 mm) from that is divided by the gauge point distance (50 mm) to achieve the elongation rate. (%) Was calculated.

-Crystal particle size Each aluminum alloy foil is immersed in a 20% by volume perchloric acid + 80% by volume ethanol mixed solution, electropolished at a voltage of 20V, washed with water, and then washed with water at a voltage of 30V in a 5% by volume aqueous borohydride. After forming an anodic oxide film in the above, the crystal grains were observed and photographed with a polarizing optical microscope. The average crystal grain size was measured by the cutting method from the crystal grain photograph.

-HAGB length / LAGB length After electropolishing the foil surface, crystal orientation analysis is performed by SEM-EBSD, and grain boundaries (HAGB) with an orientation difference of 15 ° or more between crystal grains and an orientation difference of 2 ° or more 15 Small grain boundaries (LAGB) below ° were observed. The visual field size of 45 × 90 μm was measured in three visual fields at a magnification of × 1000, the lengths of HAGB and LAGB in the visual field were obtained, and the ratio was calculated.

-Limited molding height The molding height was evaluated by a square tube molding test. The test was performed with a universal thin plate forming tester (Model 142/20 manufactured by ERICHSEN), and a 30 μm-thick aluminum foil was subjected to a square punch (side length L = 37 mm, corner chamfering) having the shape shown in FIG. Diameter R = 4.5 mm) was used. As the test conditions, the wrinkle suppressing force was 10 kN, the scale of the punch rising speed (molding speed) was 1, and mineral oil was applied as a lubricant to one side of the foil (the side where the punch hits). The punch that rises from the bottom of the device hits the foil, and the foil is molded, but the maximum height of the punch that can be molded without cracks or pinholes when three consecutive moldings are performed is the limit molding height of the material. It was defined as (mm). The height of the punch was changed at 0.5 mm intervals. In the product of the present invention, a molding height of 8.0 mm or more was accepted.

-Density of the intermetallic compound The intermetallic compound is obtained by cutting the parallel cross section (RD-ND surface) of the foil with a CP (Cross section policer) and using a field emission scanning electron microscope (FE-SEM: NVision 40 manufactured by Carl Zeiss). And observed. For the "Al-Fe-based intermetallic compound having a particle size of 1 μm or more and less than 3 μm", five visual fields observed at a magnification of × 2000 times were image-analyzed to calculate the density. For the "Al-Fe-based intermetallic compound having a particle size of 0.1 μm or more and less than 1 μm", 10 visual fields observed at a magnification of × 10000 times were image-analyzed to calculate the density. The particle size was determined by the equivalent circle diameter.

Crystal orientation density The Cube orientation was {001} <100>, the Cu orientation was {112} <111>, and the R orientation was {123} <634>. For each azimuth density, the incomplete pole map of {200}, {220}, and {111} is measured by the X-ray diffractometry, and the result is used to calculate the three-dimensional azimuth distribution function (ODF). And evaluated.

The results of each of the above measurements are shown in Table 2.

D Length of one side R Chamfer diameter

Claims (3)

Fe: 1.2% by mass or more and 1.6% by mass or less, Si: 0.05% by mass or more and 0.15% by mass or less, Cu: 0.005% by mass or more and 0.1% by mass or less, Mn: It is an aluminum alloy foil regulated to 0.01% by mass or less and the balance is composed of Al and other unavoidable impurities. The average crystal grain size of the aluminum alloy foil is 20 to 30 μm, and the maximum crystal grain size / An aluminum alloy foil having an average crystal grain size of ≦ 3.0, a Cube orientation density of 10 or more, a Cu orientation density of 20 or less, and an R orientation density of 15 or less. In crystal orientation analysis per unit area by backscattered electron diffraction (EBSD), the lengths of large grain boundaries (HAGB) with orientation difference of 15 ° or more and small grain boundaries (LAGB) with orientation difference of 2 ° or more and less than 15 °. The aluminum alloy foil according to claim 1, wherein the ratio is "HAGB length / LAGB length> 2.0". The number density of Al-Fe intermetallic compounds having a particle size (equivalent to a circle, the same applies hereinafter) of 1.0 to 3.0 μm is 6.0 × 10 ³ pieces / mm ² or less, and a particle size of 0.1 μm or more. The aluminum alloy foil according to claim 1 or 2, wherein the same number density of less than 1.0 μm is 1.0 × 10 ⁴ pieces / mm ^{2 or more.}

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