Aluminum alloy and aluminum alloy material

Abstract

[Problem] To provide: an aluminum alloy material which combines high strength, good moldability, and high thermal conductivity, and which has a slow decrease in strength due to annealing; and an aluminum alloy for obtaining the aluminum alloy material. [Solution] An aluminum alloy which contains 0.5 to 2.5 mass% of Fe and 0.5 to 2.5 mass% of Ni, with the remainder comprising Al and unavoidable impurities, and which is characterized in that the ratio of the content (mass%) of Ni / the content (mass%) of Fe is 0.3 to 4.0, and the total of the content (mass%) of Fe and the content (mass%) of Ni is 1.5 to 5.0 mass%.

Description

Technical Field

[0001] This invention relates to an Al-Fe-Ni based aluminum alloy and aluminum alloy materials, and more particularly to an aluminum alloy sheet suitable for use in battery casings and covers. Background Technology

[0002] Aluminum alloys are lightweight and have excellent machinability, making them effective for use in various components such as general utensils, building materials, shipbuilding materials, heat sink materials, and various containers. For example, in battery casings and covers where excellent heat dissipation is required, Japanese Industrial Standards (JIS)-3003 (Al-Mn) alloys, whose strength is increased through work hardening, are used.

[0003] More specifically, in the battery casing and cover, cold-rolled 3000 series aluminum alloys that have been work-hardened by tempering with H24 or H14 are used. However, if the temperature is maintained above 350°C, the strength drops sharply. With the increasing capacity of batteries in recent years, the charge and discharge temperatures have become higher. When using work-hardened materials, they may soften during battery use and fail to maintain sufficient strength.

[0004] Furthermore, welding is often involved in the manufacturing of aluminum alloy structures. As a result, significant softening occurs in the heat-affected zone (HAZ) of the work-hardened aluminum alloy, and the strength of the aluminum alloy structure is determined by this HAZ. In other words, the inherent strength or reliability of the aluminum alloy cannot be fully utilized.

[0005] Furthermore, it is known that work-hardened materials lack ductility, especially with low uniform elongation. Additionally, they are difficult to exhibit isotropic ductility, and the stretching direction has a greater impact on uniform elongation. Therefore, work-hardened aluminum alloys are unsuitable for use in high-quality aluminum alloy components or aluminum alloy components with complex shapes.

[0006] In response, the inventors disclosed an aluminum alloy sheet for a battery cover used in the forming of an integrated explosion-proof valve in Patent Document 1 (Japanese Patent Application Publication No. 2020-50889). The sheet is characterized by having the following composition: Fe: 0.85%–1.50% by mass, Mn: 0.30%–0.70% by mass, Ti: 0.002%–0.15% by mass, and B: less than 0.05% by mass, with the remainder being Al and impurities. The Fe / Mn ratio is limited to 1.8–3.5, and the impurities Si are limited to less than 0.40% by mass, Cu to less than 0.03% by mass, Mg to less than 0.05% by mass, and V to less than 0.03% by mass. Furthermore, the sheet has a tensile strength of 95 MPa or more, a 0.2% endurance of 40 MPa or more, an elongation of 40% or more, a recrystallized structure, and an elongation of 6.5% or more after cold rolling at 80% reduction.

[0007] The aluminum alloy sheet for the battery cover described in Patent Document 1 has a tensile strength of 95 MPa or more, a 0.2% endurance of 40 MPa or more, an elongation of 40% or more, a recrystallized structure, and an elongation of 6.5% or more after cold rolling with a reduction of 80%. Therefore, it has moderate strength, excellent resistance to deformation and formability, and thus the working pressure deviation of the integrally formed explosion-proof valve is small, and the resistance to repeated fatigue is excellent.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2020-50889 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] The aluminum alloy sheet for the battery cover described in Patent Document 1 has good ductility and formability, and also suppresses the decrease in strength that occurs with rising temperature. However, its tensile strength is only about 95 MPa, which is not sufficient for various applications.

[0013] In view of the problems of the prior art as described above, the object of the present invention is to provide an aluminum alloy material that has high strength, good formability and high thermal conductivity, and whose strength decreases slowly due to annealing, as well as an aluminum alloy for obtaining said aluminum alloy material.

[0014] Technical means to solve the problem

[0015] To achieve the aforementioned objective, the inventors have repeatedly and diligently studied the relationship between the composition, mechanical properties, and thermal conductivity of aluminum alloys. As a result, they discovered that adding appropriate amounts of Fe and Ni to aluminum alloys is extremely effective, thus completing this invention.

[0016] That is, the present invention provides an aluminum alloy, characterized in that:

[0017] Contains Fe: 0.5%–2.5% by mass

[0018] Ni: 0.5% by mass to 2.5% by mass

[0019] The remaining portion contains Al and unavoidable impurities.

[0020] The ratio of Ni content (mass%) to Fe content (mass%) is 0.3 to 4.0.

[0021] The total content of Fe (mass%) and the content of Ni (mass%) is 1.5% to 5.0% by mass.

[0022] In the aluminum alloy of the present invention, by adding Ni to the Fe-containing aluminum alloy, the crystal structure changes from Al3Fe to Al9FeNi, and the crystallization temperature decreases. As a result, fine crystals (Al9FeNi) are dispersed abundantly and uniformly in the Al matrix, increasing the strength of the aluminum alloy and suppressing the decrease in strength of the heat-affected zone. Furthermore, the addition of Ni to the Al matrix promotes recovery during high-strain processing at room temperature, thus making recrystallization difficult to occur even when the cold-rolled aluminum alloy is annealed, and maintaining high strength even for annealed O-materials.

[0023] Furthermore, in the aluminum alloy of the present invention, since the aluminum alloy material can be made strong without work hardening, an aluminum alloy material with excellent ductility can be obtained, especially with increased uniform elongation. In addition, compared with work-hardened materials, the anisotropy of ductility is reduced, which imparts good formability to the aluminum alloy material. Furthermore, Ni is an element that hardly dissolves into the Al matrix phase, and Fe is expelled from the matrix phase as Al9FeNi, thus imparting high thermal conductivity to the aluminum alloy material.

[0024] In the aluminum alloy of the present invention, the ratio of Ni content (mass%) to Fe content (mass%) is 0.3 to 4.0. When the ratio of Ni content (mass%) to Fe content (mass%) is 0.3 or higher, the effect of Ni addition is sufficiently demonstrated. On the other hand, even if the ratio of Ni content (mass%) to Fe content (mass%) exceeds 4.0, the effect of Ni addition cannot be significantly improved, and Ni is an expensive element; therefore, the upper limit of the ratio of Ni content (mass%) to Fe content (mass%) is 4.0.

[0025] Furthermore, in the aluminum alloy of the present invention, the total content of Fe (mass%) and Ni (mass%) is 1.5% to 5.0% by mass. By setting the total content of Fe (mass%) and Ni (mass%) to 1.5% by mass or more, a sufficient amount of Al9FeNi can be dispersed for the high strength of the aluminum alloy. On the other hand, even if the total content of Fe (mass%) and Ni (mass%) exceeds 5.0% by mass, further high strength of the aluminum alloy cannot be expected along with the dispersion of Al9FeNi, and toughness may also decrease. In addition, Ni is an expensive element, therefore the upper limit of the total content of Fe (mass%) and Ni (mass%) is 5.0% by mass.

[0026] Furthermore, in the aluminum alloy of the present invention, it is preferable to also contain Mn: more than 0% by mass and less than 1.5% by mass as an optional additive element. By adding an appropriate amount of Mn, the decrease in the thermal conductivity of the aluminum alloy can be minimized, while achieving high strength.

[0027] Furthermore, in the aluminum alloy of the present invention, it is preferable to also contain Si: more than 0% by mass and less than 1.0% by mass as an optional additive element. By adding an appropriate amount of Si, the decrease in the thermal conductivity of the aluminum alloy can be minimized, while achieving high strength. In particular, by adding Si together with Mn to form an Al-Si-Mn compound, the strength of the aluminum alloy can be efficiently increased.

[0028] Furthermore, the present invention provides an aluminum alloy material, characterized in that it comprises the aluminum alloy of the present invention. Because the aluminum alloy material of the present invention comprises the aluminum alloy of the present invention, it possesses high strength, good formability, and high thermal conductivity, and exhibits a slow decrease in strength due to annealing.

[0029] The aluminum alloy material of the present invention preferably has a thermal conductivity of 200 W / m·K or higher at room temperature. With a thermal conductivity of 200 W / m·K or higher, it can be suitable for use as a battery material (casing and cover), etc.

[0030] Furthermore, the aluminum alloy material of the present invention preferably exhibits a tensile strength of 100 MPa or more, a 0.2% tensile strength of 50 MPa or more, and a total elongation of 25% or more in a tensile test at room temperature. Because the aluminum alloy material possesses these tensile properties, it can be suitable for use as components requiring high strength or reliability.

[0031] Furthermore, the aluminum alloy material of the present invention preferably exhibits a uniform elongation of 15% or more in a tensile test at room temperature. By demonstrating a uniform elongation of 15% or more in the aluminum alloy material, well-formable components can be obtained.

[0032] Furthermore, the aluminum alloy material of the present invention is preferably characterized by a uniform elongation difference of less than 4% in each of the 0°, 45°, and 90° directions relative to the rolling direction during a tensile test at room temperature. By having an isotropic uniform elongation, a well-formable component can be obtained from the aluminum alloy material.

[0033] Furthermore, the aluminum alloy material of the present invention preferably has an average circular diameter of 1.5 μm or less for the compound particles. By having an average circular diameter of 1.5 μm or less for the compound particles, a sufficient number of compound particles can be dispersed in the Al matrix, and the spacing between the compound particles can be narrowed. As a result, the compound particles effectively hinder the movement of dislocations, thus imparting high strength to the aluminum alloy material. Here, the compound particles in the aluminum alloy material of the present invention are Al-Fe-Ni based compounds or Al-Si-Mn based compounds.

[0034] Furthermore, the aluminum alloy material of the present invention preferably has an absolute maximum diameter of 15 μm or less for the compound particles. By setting the absolute maximum diameter of the compound particles to 15 μm or less, damage originating from the compound particles or the compound particle / Al matrix interface can be suppressed.

[0035] Furthermore, the aluminum alloy material of the present invention preferably has a particle number surface density of 40,000 particles / mm². 2 That's all. The particle number surface density of the compound particles was set to 40,000 particles / mm². 2 In this way, the compound particles effectively hinder the movement of dislocations, thus imparting high strength to the aluminum alloy. Furthermore, the sufficient expulsion of Fe and Ni from the Al matrix contributes to high electrical conductivity in the aluminum alloy.

[0036] The effects of the invention

[0037] The present invention provides an aluminum alloy material that has high strength, good formability and high thermal conductivity, and whose strength decreases slowly due to annealing, as well as an aluminum alloy for obtaining the aluminum alloy material. Attached Figure Description

[0038] [ Figure 1 [A graph represents the relationship between the electrical conductivity and thermal conductivity of metallic materials.]

[0039] [ Figure 2 [ ] is the stress-strain curve in Example 3.

[0040] [ Figure 3 [ ] is the stress-strain curve in Comparative Example 1.

[0041] [ Figure 4 [ ] is the stress-strain curve in Comparative Example 2.

[0042] [ Figure 5 [This is a graph showing the relationship between 0.2% toughness of aluminum alloy and annealing temperature.]

[0043] [ Figure 6 [This is the optical microscope observation result of the aluminum alloy material obtained in Example 3.]

[0044] [ Figure 7 [This is the optical microscope observation result of the aluminum alloy material obtained in Example 4.]

[0045] [ Figure 8 [Image shows the optical microscope observation results of the aluminum alloy material obtained in Comparative Example 1.]

[0046] [ Figure 9 [Image shows the optical microscope observation results of the aluminum alloy material obtained in Comparative Example 3.]

[0047] [ Figure 10 [This is the microstructure observation result of the aluminum alloy material obtained in Example 3.]

[0048] [ Figure 11 [This is the microstructure observation result of the aluminum alloy material obtained in Example 4.]

[0049] [ Figure 12 [This refers to the microstructure observation results of the aluminum alloy material obtained in Comparative Example 2.]

[0050] [ Figure 13 [This refers to the microstructure observation results of the aluminum alloy material obtained in Comparative Example 3.]

[0051] [ Figure 14 [This refers to the microstructure observation results of the aluminum alloy material obtained in Comparative Example 7.] Detailed Implementation

[0052] The following describes in detail representative embodiments related to the aluminum alloys and aluminum alloy materials of the present invention, but the present invention is not limited to these.

[0053] 1. Aluminum alloy

[0054] In order to impart high strength, good formability, and high thermal conductivity to the aluminum alloy of the present invention, and to suppress the strength loss caused by annealing, the content of Fe and Ni has been specifically optimized. The constituent elements of the aluminum alloy of the present invention will be described below.

[0055] (1) Required additional elements

[0056] Fe: 0.5% by mass to 2.5% by mass

[0057] The Fe content is 0.5% to 2.5% by mass. By setting the Fe content to 0.5 wt% or more in an aluminum alloy containing an appropriate amount of Ni, the strength of the aluminum alloy can be increased through the formation of Al-Fe-Ni compounds. Furthermore, by setting the Fe content to 2.5% by mass or less, the formation of coarse Al-Fe-Ni compounds that reduce toughness and ductility can be suppressed. The Fe content is preferably set to 1.0% to 2.0% by mass, more preferably 1.2% to 1.8% by mass.

[0058] Ni: 0.5% by mass to 2.5% by mass

[0059] The Ni content is 0.5% to 2.5% by mass. By setting the Ni content to 0.5 wt% or more in an aluminum alloy containing an appropriate amount of Fe, the strength of the aluminum alloy can be increased through the formation of Al-Fe-Ni compounds. Furthermore, by setting the Ni content to 2.5% by mass or less, the formation of coarse Al-Fe-Ni compounds that reduce toughness and ductility can be suppressed. The Ni content is preferably set to 1.0% to 2.0% by mass, more preferably 1.2% to 1.8% by mass.

[0060] Ni is an element that hardly dissolves into the Al matrix at room temperature. If Ni-containing aluminum alloys are subjected to high-strain processing at room temperature, a decrease in strength occurs. This is because recovery occurs in the high-strain region, and by utilizing this phenomenon, even when annealing cold-rolled aluminum alloys, a non-recrystallized structure can be obtained. More specifically, even with final annealing at 450°C, a non-recrystallized structure is achieved, thus suppressing the decrease in strength.

[0061] Ni content (mass%) / Fe content (mass%): 0.3–4.0

[0062] The Ni content (mass%) / Fe content (mass%) ratio is 0.3 to 4.0. When the Ni content (mass%) / Fe content (mass%) ratio is 0.3 or higher, the effect of Ni addition is fully manifested. On the other hand, even if the Ni content (mass%) / Fe content (mass%) ratio exceeds 4.0, the effect of Ni addition cannot be significantly improved, and Ni is an expensive element; therefore, the upper limit of the Ni content (mass%) / Fe content (mass%) ratio is 4.0. The Ni content (mass%) / Fe content (mass%) ratio is preferably set to 0.5 to 3.5, more preferably 1.0 to 2.0. Here, the value of the Ni content (mass%) / Fe content (mass%) in the aluminum alloy of the present invention is the value obtained by rounding the second decimal place of the value obtained from the calculation of the Ni content (mass%) / Fe content (mass%) ratio to the first decimal place.

[0063] The combined content of Fe (mass%) and Ni (mass%) is 1.5% to 5.0% by mass.

[0064] The total content of Fe (mass%) and Ni (mass%) is 1.5% to 5.0% by mass. By setting the total content of Fe (mass%) and Ni (mass%) to 1.5% by mass or more, a sufficient amount of Al9FeNi can be dispersed for the high strength of the aluminum alloy. On the other hand, even if the total content of Fe (mass%) and Ni (mass%) exceeds 5.0% by mass, further high strength of the aluminum alloy cannot be expected along with the dispersion of Al9FeNi, and toughness may also decrease. In addition, Ni is an expensive element, so the upper limit of the total content of Fe (mass%) and Ni (mass%) is 5.0% by mass. The total content of Fe (mass%) and Ni (mass%) is preferably set to 2.0% to 4.5% by mass, more preferably 2.5% to 4.0% by mass.

[0065] (2) Adding elements arbitrarily

[0066] Mn: greater than 0% by mass and less than 1.5% by mass

[0067] By adding Mn at a concentration greater than 0% and less than 1.5% by mass, the decrease in thermal conductivity of the aluminum alloy can be minimized while achieving high strength. On the other hand, if the amount of Mn added exceeds 1.5% by mass, the thermal conductivity of the aluminum alloy will be less than 200 W / m·K. The preferred amount of Mn added is 0.5% to 1.0% by mass.

[0068] Si: greater than 0% by mass and less than 1.0% by mass

[0069] By adding Si in amounts greater than 0% and less than 1.0% by mass, the decrease in thermal conductivity of aluminum alloys can be minimized while simultaneously achieving high strength. In particular, by adding Si together with Mn to form Al-Si-Mn compounds, the strength of aluminum alloys can be efficiently increased. On the other hand, if the amount of Si added exceeds 1.0% by mass, eutectic Si particles are formed, which are prone to recrystallization during final annealing, resulting in a decrease in the strength of the aluminum alloy. The amount of Si added is preferably set to 0.05% to 0.5% by mass, more preferably 0.07% to 0.3% by mass.

[0070] (3) Unavoidable impurities

[0071] Specific examples of unavoidable impurity elements include: magnesium (Mg), copper (Cu), zinc (Zn), lithium (Li), nickel (Ni), titanium (Ti), calcium (Ca), sodium (Na), strontium (Sr), yttrium (Y), niobium (Nb), molybdenum (Mo), tungsten (W), antimony (Sb), beryllium (Be), phosphorus (P), vanadium (V), tin (Sn), lead (Pb), bismuth (Bi), cobalt (Co), silver (Ag), gallium (Ga), scandium (Sc), cerium (Ce), boron (B), carbon (C), nitrogen (N), and oxygen (O), but copper (Cu) is preferably strictly excluded. If copper (Cu) is present, even in small amounts, the thermal conductivity of the aluminum alloy decreases, and grain boundary corrosion is easily carried out, making it unsuitable for use as battery materials (casings and covers).

[0072] These unavoidable impurity elements may be elements that are unavoidably present in the aluminum raw material, unavoidably mixed in during the manufacture of aluminum alloys, or modifiers added intentionally when grain-refining elements such as titanium, boron, and zirconium are added. The content of these unavoidable impurity elements is not particularly limited as long as it does not impair the effects of the present invention, but is preferably set to 0.5% by mass or less, more preferably 0.3% by mass or less, and particularly preferably 0.2% by mass or less, individually. Furthermore, the content of each element can be determined by inductively coupled plasma (ICP) luminescence spectrophotometry and inert gas melting-infrared absorption spectrometry, etc.

[0073] 2. Aluminum alloy material

[0074] The aluminum alloy material of the present invention has high strength, good formability and high thermal conductivity, and suppresses the strength loss caused by annealing. The microstructure and characteristics of the aluminum alloy material of the present invention will be described below.

[0075] (1) Organization

[0076] The aluminum alloy material of the present invention has a microstructure in which compound particles (second phase particles) such as Al-Fe-Ni system compounds or Al-Si-Mn system compounds are dispersed in Al matrix.

[0077] The average circular diameter of the compound particles is preferably 1.5 μm or less. By having an average circular diameter of 1.5 μm or less, a sufficient number of compound particles can be dispersed in the Al matrix, and the spacing between the compound particles can be narrowed. As a result, the compound particles effectively hinder dislocation movement, imparting high strength to the aluminum alloy. More preferably, the average circular diameter of the compound particles is 1.0 μm or less.

[0078] The absolute maximum diameter of the compound particles is preferably 15 μm or less. By setting the absolute maximum diameter of the compound particles to 15 μm or less, damage originating from the compound particles or the compound particle / Al matrix interface can be suppressed. More preferably, the absolute maximum diameter of the compound particles is 10 μm or less, and most preferably, 8 μm or less.

[0079] The preferred particle number surface density of the compound particles is 40,000 particles / mm². 2 That's all. The particle number surface density of the compound particles was set to 40,000 particles / mm². 2 In this way, the compound particles effectively hinder dislocation movement, imparting high strength to the aluminum alloy. Furthermore, the sufficient expulsion of Fe and Ni from the Al matrix contributes to high electrical conductivity in the aluminum alloy. A more preferable particle number areal density is 50,000 particles / mm². 2 The optimal value is 60,000 pieces / mm. 2 above.

[0080] The method for determining the average circular equivalent diameter, absolute maximum diameter, and particle number areal density of the compound particles is not particularly limited, as long as it does not impair the effects of the present invention; any existing known method can be used for measurement. For example, an aluminum alloy material can be cut at any cross-section, and the obtained cross-sectional sample can be observed using an optical microscope or a scanning electron microscope, and measurements can be made based on the observation results. Here, the obtained tissue photographs are binarized through image processing, thereby allowing for simple and efficient extraction of information related to the compound particles. Furthermore, depending on the observation method, mechanical grinding, polishing, electrolytic grinding, and etching of the cross-sectional sample are all acceptable.

[0081] (2) Tensile properties

[0082] The aluminum alloy material of the present invention preferably exhibits the following properties in a tensile test at room temperature: a tensile strength of 100 MPa or more, a 0.2% tensile strength of 50 MPa or more, and a total elongation of 25% or more. These tensile properties make the aluminum alloy material suitable for use in components requiring high strength or reliability. More preferably, the tensile strength is 120 MPa or more, and most preferably 140 MPa or more. Furthermore, the 0.2% tensile strength is more preferably 60 MPa or more, and most preferably 70 MPa or more. Additionally, the total elongation is more preferably 30% or more, and most preferably 35% or more.

[0083] Furthermore, the aluminum alloy material of the present invention preferably exhibits a uniform elongation of 15% or more in a tensile test at room temperature. By demonstrating a uniform elongation of 15% or more in the aluminum alloy material, well-formable components can be obtained. A uniform elongation of 18% or more is more preferred, and 20% or more is most preferred.

[0084] Furthermore, the aluminum alloy material of the present invention preferably has a uniform elongation difference of less than 4% in each direction (0°, 45°, and 90° relative to the rolling direction) during a tensile test at room temperature. By having an isotropic uniform elongation, a well-formed component can be obtained. Here, "difference in uniform elongation" refers to the difference in absolute values ​​obtained by measuring each tensile test piece taken with the tensile direction at 0°, 45°, and 90° relative to the rolling direction. More preferably, the difference in uniform elongation is less than 3%, and most preferably less than 2%.

[0085] (3) Thermal conductivity

[0086] The aluminum alloy material of the present invention preferably has a thermal conductivity of 200 W / m·K or higher at room temperature. With a thermal conductivity of 200 W / m·K or higher, it can be suitably used as a battery material (casing and cover). A thermal conductivity of 220 W / m·K or higher is more preferred, and 240 W / m·K or higher is most preferred.

[0087] There are no particular limitations on the method for determining the thermal conductivity of aluminum alloys; various existing methods, such as the flash evaporation method or the temperature tilt method, can be used. Alternatively, the thermal conductivity can be calculated from the electrical conductivity. Here, it is known that the electrical and thermal conductivity of metallic materials, according to the Wiedemann-Franz rule, exhibit the following relationship: Figure 1 The relationship is as shown in (Kobe Steel Technical Bulletin, Vol. 71 No. 2, June 2022, p. 29).

[0088] 3. Manufacturing methods for aluminum alloy materials

[0089] The method for manufacturing the aluminum alloy material of the present invention is not particularly limited as long as it does not impair the effect of the present invention. By using the aluminum alloy of the present invention and performing O treatment as the final annealing, an aluminum alloy material with uniform tensile properties and good ductility, and exhibiting good formability and high thermal conductivity can be obtained.

[0090] More specifically, for example, a casting material containing the aluminum alloy of the present invention is subjected to homogenization treatment, and then an aluminum alloy sheet with a desired thickness is produced by hot rolling and cold rolling, and finally annealed at 300°C to 500°C, thereby obtaining the aluminum alloy material of the present invention.

[0091] The above describes representative embodiments of the present invention, but the present invention is not limited to these and various design changes can be made, all of which are included in the technical scope of the present invention.

[0092] Example

[0093] Example

[0094] Cast aluminum alloys with the compositions shown in Table 1 as examples were obtained by direct cooling (DC) continuous casting. Table 1 also lists the values ​​for "Ni content (mass%) / Fe content (mass%)" and "total of Fe content (mass%) and Ni content (mass%)". The value of Ni content (mass%) / Fe content (mass%) is expressed as the value obtained by rounding the second decimal place of the calculated value of Ni content (mass%) / Fe content (mass%) to the first decimal place. In all cases, the aluminum alloys in the examples have a Ni content (mass%) / Fe content (mass%) of 0.3 to 4.0 and a total Fe content (mass%) / Ni content (mass%) of 1.5 to 5.0 mass.

[0095] [Table 1]

[0096]

[0097] Next, the obtained casting material was homogenized at 560°C for 6 hours, then hot-rolled to a thickness of 7 mm, and cold-rolled to a final thickness of 1 mm. Subsequently, a final annealing (O treatment) was performed at 450°C for 3 hours to obtain the aluminum alloy material as an embodiment of the present invention.

[0098] The microstructure of arbitrary cross-sections of the obtained aluminum alloy materials was observed using an optical microscope. Commercially available image processing software was used to binarize the obtained microstructure images, and compound particles dispersed in the Al matrix were extracted. Furthermore, for the extracted compound particles, the circle equivalent average diameter, absolute maximum diameter, and particle number surface density were calculated. Here, the circle equivalent diameter is the diameter of a circle whose area is equivalent to that of each extracted compound particle, and the absolute maximum diameter is the largest of the diameters connecting the centroid of the compound particle and the two points on its outer periphery. The obtained values ​​are shown in Table 2.

[0099] [Table 2]

[0100]

[0101] Tensile test specimens (JIS Z 2201 14B specimens) were collected from various aluminum alloys, and tensile properties were evaluated at room temperature according to the tensile test method of JIS Z 2241. The tensile directions of the specimens were set as 0° (L direction), 45° direction, and 90° direction (LT direction) relative to the rolling direction. Furthermore, regarding elongation, total elongation and uniform elongation were measured. The obtained tensile properties are shown in Table 2.

[0102] Next, the electrical conductivity of each aluminum alloy was measured, and the obtained electrical conductivity was converted into thermal conductivity. For the conductivity measurement, a digital conductivity meter (AutoSigma 3000 / DL) manufactured by Hocking was used, and... Figure 1 Based on the relationship, four times the electrical conductivity was set as the thermal conductivity. The obtained electrical and thermal conductivity values ​​are shown in Table 2.

[0103] Comparative Examples

[0104] A cast aluminum alloy with the composition shown in Table 1 as a comparative example was used, except that the aluminum alloy material was obtained in the same manner as in the examples. Here, only Comparative Example 1 underwent H24 treatment and not O treatment. The conditions for H24 treatment were set at 280°C for 3 hours.

[0105] Here, in Comparative Examples 1 to 3, the ratio of Ni content (mass%) to Fe content (mass%) is less than 0.3, and in Comparative Examples 1 to 6, 9 and 11, the total of Fe content (mass%) and Ni content (mass%) is less than 1.5 mass.

[0106] Furthermore, the obtained aluminum alloy was evaluated in the same manner as in the embodiment. The evaluation results are shown in Table 2. As shown in Table 2, the aluminum alloy exhibits a tensile strength of 100 MPa or more, a 0.2% endurance of 50 MPa or more, and a total elongation of 25% or more in all components and all tensile directions. Although the aluminum alloy was subjected to O treatment, the strength decrease caused by annealing was slow, thus maintaining a tensile strength of 100 MPa or more. In addition, the aluminum alloy exhibits a uniform elongation of 15% or more in all components and all tensile directions, and the difference in uniform elongation in each direction relative to the rolling direction (0°, 45°, and 90°) is within 4%.

[0107] In contrast, in Comparative Example 1, which underwent work hardening through H24 treatment, both the total elongation and uniform elongation were low. Furthermore, the differences in elongation in the 0°, 45°, and 90° directions relative to the rolling direction were extremely large. In Comparative Example 2, which involved O treatment on an aluminum alloy with the same composition as Comparative Example 1, although the total elongation and uniform elongation were improved, the 0.2% endurance was low, and the differences in uniform elongation in the 0°, 45°, and 90° directions relative to the rolling direction exceeded 4%. As representative examples, the stress-strain curves of Example 3, Comparative Example 1, and Comparative Example 2 are shown respectively. Figure 2 , Figure 3 and Figure 4 It was found that the aluminum alloy material of Example 3 has isotropic tensile properties compared with the aluminum alloy materials of Comparative Example 1 and Comparative Example 2.

[0108] Furthermore, for example, in the aluminum alloys of Comparative Examples 7 to 9, the differences in uniform elongation in each direction relative to the rolling direction (0°, 45°, and 90°) were small. However, in Comparative Examples 7 and 9, the areal density of the compound particles was low, and the 0.2% strength was low. Furthermore, in Comparative Example 7, 2% by mass of Si was contained, resulting in the formation of eutectic Si (average diameter of the compound particles: 1.7 μm, absolute maximum diameter: 17.7 μm). After final annealing at 450°C, recrystallization occurred, leading to a decrease in strength. In Comparative Example 8, coarse compound particles were formed, resulting in low thermal conductivity. Regarding Comparative Example 11, which had a low Ni content, the thermal conductivity was less than 200 W / m·K.

[0109] In addition, in Comparative Examples 3 to 6 with low Ni content and Comparative Example 10 with low Fe content, the 0.2% toughness of the aluminum alloy was low.

[0110] To evaluate the strength reduction of aluminum alloy materials caused by annealing, the aluminum alloy materials obtained in Examples 3, 4, Comparative Example 1, and Comparative Example 3 were further subjected to annealing treatment, and tensile tests in the rolling direction were performed in the same manner as above. The annealing temperatures were set to 300°C, 350°C, 400°C, 450°C, and 500°C, and the holding time was set to 3 hours. The relationship between the obtained 0.2% endurance and the annealing temperature is shown in the figure. Figure 5 middle.

[0111] The work-hardened aluminum alloy of Comparative Example 1 exhibits high strength at room temperature, but its 0.2% strength decreases significantly when annealed at temperatures above 350°C. On the other hand, the aluminum alloy of Comparative Example 3, which underwent O treatment, showed a small decrease in strength due to annealing, but its absolute value of 0.2% strength was low. In contrast, the aluminum alloys obtained in Examples 3 and 4 exhibit high strength at room temperature and suppress the decrease in strength caused by annealing. This indicates that the aluminum alloy of the present invention can suppress the decrease in strength or hardness of the heat-affected zone during welding.

[0112] The optical microscopic observation results of the cross-sections of the aluminum alloy materials obtained in Examples 3, 4, Comparative Example 1, and Comparative Example 3 are shown below. Figure 6 , Figure 7 , Figure 8 and Figure 9 It was found that, compared with Comparative Example 1 and Comparative Example 3, a large number of fine compound particles were dispersed in Examples 3 and 4.

[0113] The tissue observation results from the cross-sections of Examples 3, 4, Comparative Example 2, Comparative Example 3, and Comparative Example 7 are shown below. Figure 10 , Figure 11 , Figure 12 , Figure 13 and Figure 14 The cross-section was etched. It was found that in Examples 3 and 4, the non-recrystallized structure was maintained even after O treatment. In contrast, in Comparative Examples 2, 3, and 7, recrystallization occurred due to O treatment.

[0114] Based on the above results, it is known that in order to obtain aluminum alloys that have high strength, good formability, high thermal conductivity, and slow strength loss due to annealing, it is effective to optimize the content of Ni and Fe and implement O treatment.

Claims

1. An aluminum alloy, characterized in that: Contains Fe: 0.5%–2.5% by mass Ni: 0.5% by mass to 2.5% by mass The remaining portion contains Al and unavoidable impurities. The ratio of Ni content (mass%) to Fe content (mass%) is 0.3 to 4.

0. The total content of Fe (mass%) and the content of Ni (mass%) is 1.5% to 5.0% by mass.

2. The aluminum alloy according to claim 1, characterized in that: It also contains Mn: more than 0% by mass and less than 1.5% by mass. As an arbitrary added element.

3. The aluminum alloy according to claim 1 or 2, characterized in that: It also contains Si: more than 0% by mass and less than 1.0% by mass. As an arbitrary added element.

4. An aluminum alloy material, characterized in that: It includes the aluminum alloy as described in claim 1 or 2.

5. The aluminum alloy material according to claim 4, characterized in that: The thermal conductivity at room temperature is above 200 W / m·K.

6. The aluminum alloy material according to claim 4, characterized in that: In a tensile test at room temperature, the tensile strength is above 100 MPa, the 0.2% endurance is above 50 MPa, and the total elongation is above 25%.

7. The aluminum alloy material according to claim 6, characterized in that: In a tensile test at room temperature, the uniform elongation is greater than 15%.

8. The aluminum alloy material according to claim 6, characterized in that: In a tensile test at room temperature, the difference in uniform elongation in each of the 0°, 45°, and 90° directions relative to the rolling direction is within 4%.

9. The aluminum alloy material according to claim 4, characterized in that: The average diameter of the circumference of the compound particles is less than 1.5 μm.

10. The aluminum alloy material according to claim 4, characterized in that: The absolute maximum diameter of the compound particles is less than 15 μm.

11. The aluminum alloy material according to claim 4, characterized in that: The particle number surface density of the compound particles is 40,000 / mm². 2 above.

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