Highly elastic aluminum alloy casting material

Abstract

The present invention provides a highly elastic aluminum alloy casting material having a high elastic modulus and a high specific elastic modulus and having improved castability, brittleness resistance, machinability, and tensile properties. The highly elastic aluminum alloy casting material comprises: 17.0 (exclusive) to 23 wt% of silicon (Si); 6.0 (exclusive) to 18 wt% of nickel (Ni); 0.2 wt% to 0.5 wt% of magnesium (Mg); and the balance being aluminum (Al) and inevitable impurities.

Description

High-elasticity aluminum alloy casting material

[0001] The present invention relates to an aluminum alloy casting material, and more particularly, to a high-elasticity aluminum alloy casting material having a high elastic modulus and specific elastic modulus.

[0002] The Young's modulus is a measure of the stiffness of a solid material or component, indicating its resistance to displacement. In other words, it represents the material's ability to withstand and maintain its shape under loads such as tension or compression. A higher Young's modulus indicates better stiffness. Furthermore, in structures where deformation, rather than destruction, is important, the Young's modulus is a key characteristic. Furthermore, for lightweight structures, the Young's modulus, calculated by dividing the Young's modulus by the density (that is, Young's modulus / density), is an important characteristic. Structural components of transportation equipment such as automobiles, such as end plates for fuel cell vehicles, and machine tools require lightweight, high-elasticity alloy materials; higher Young's modulus translates to higher efficiency.

[0003] Aluminum alloy castings boast excellent castability, high strength, and lightweight properties, making them widely used in transportation equipment like automobiles and general mechanical components like machine tools. Furthermore, global environmental and energy concerns are driving the demand for lighter vehicles. This trend toward lighter, thinner, and smaller components is further expanding their applications. Furthermore, to expand the freedom of component design, the development of aluminum alloy castings with higher elastic moduli is required.

[0004] The technical problem to be achieved by the technical idea of ​​the present invention is to provide a high-elasticity aluminum alloy casting material having high elastic modulus and specific elastic modulus and improved castability, brittleness resistance, machinability, and tensile properties.

[0005] However, these tasks are exemplary and the scope of the present invention is not limited thereby.

[0006] According to one embodiment of the present invention, a high-elasticity aluminum alloy casting material may include silicon (Si) of more than 17.0 wt% to 23 wt%; nickel (Ni) of more than 6.0 wt% to 18 wt%; magnesium (Mg) of 0.2 wt% to 0.5 wt%; and the remainder being aluminum (Al) and unavoidable impurities.

[0007] According to one embodiment of the present invention, when the content of silicon is in the range of 20 wt% to 23 wt%, the correlation between the content of silicon and the content of nickel can satisfy the following equation.

[0008] Ni [wt%] ≤ (214 - 8 x Si [wt%]) / 3

[0009] According to one embodiment of the present invention, the composition may include 17.5 wt% to 20.5 wt% of silicon (Si); 7.5 wt% to 14.5 wt% of nickel (Ni); 0.2 wt% to 0.5 wt% of magnesium (Mg); and the remainder being aluminum (Al) and unavoidable impurities.

[0010] According to one embodiment of the present invention, it may further include 1.5 wt% or less of copper (Cu).

[0011] According to one embodiment of the present invention, at least one of chromium (Cr) of 0.3 wt% or less; manganese (Mn) of 0.3 wt% or less; titanium (Ti) of 0.2 wt% or less; and zirconium (Zr) of 0.2 wt% or less may be further included.

[0012] According to one embodiment of the present invention, it may further include 0.5 wt% or less of iron (Fe).

[0013] According to one embodiment of the present invention, it may further include 0.003 wt% to 0.03 wt% of phosphorus; and 0.02 wt% to 0.2 wt% of TiB2.

[0014] According to one embodiment of the present invention, the composition may further include 0.003 wt% to 0.03 wt% of phosphorus; and 0.02 wt% to 0.2 wt% of at least one of TiB2, MgAl2O4, NbB2, and AlB2 as a micronizer.

[0015] According to one embodiment of the present invention, it can have a microstructure composed of a primary Si and a needle-like Al3Ni phase.

[0016] According to one embodiment of the present invention, elastic modulus: 88 GPa to 120 GPa and inelastic modulus: 32.5 x10 6 m 2 / s 2 ~ 40 x10 6 m 2 / s 2 can satisfy.

[0017] According to one embodiment of the present invention, a microstructure having a frequency of polygonal Al3Ni phase of 10% or less can be provided.

[0018] According to one embodiment of the present invention, a microstructure can be formed in which the frequency of primary Si having a major axis length of 100 μm or more is 6% or less.

[0019] A high-elasticity aluminum alloy casting material according to the technical idea of ​​the present invention contains silicon (Si) of more than 17.0 wt% to 23 wt%; nickel (Ni) of more than 6.0 wt% to 18 wt%; and magnesium (Mg) of 0.2 wt% to 0.5 wt%, and thus has an elastic modulus of 88 GPa to 120 GPa and a specific elastic modulus of 32.5 x10 6 m 2 / s 2 ~ 40 x10 6 m 2 / s 2It can satisfy the requirements, suppress the formation of polygonal Al3Ni phase, and refine the primary Si and needle-shaped Al3Ni phases to improve castability, brittleness resistance, machinability, and tensile properties. Therefore, existing commercial aluminum alloys have a low elastic modulus of up to about 82 GPa, which has limited the design of parts, but the high-elasticity aluminum alloy casting material according to the present invention can produce an aluminum casting alloy that is lightweight and has a high elastic modulus and inelastic modulus, and thus can be applied to the production of aluminum casting parts for automobiles, machine parts, etc. that require excellent elasticity and rigidity.

[0020] The effects of the present invention described above are illustrative, and the scope of the present invention is not limited by these effects.

[0021] FIG. 1 is a phase diagram of a ternary alloy of aluminum-silicon-nickel for alloy design of a high-elasticity aluminum alloy casting material according to one embodiment of the present invention.

[0022] FIG. 2 is a graph showing the composition of silicon and nickel for comparative examples and examples of high-elasticity aluminum alloy casting materials according to one embodiment of the present invention.

[0023] FIGS. 3 and 4 are optical microscope photographs showing the microstructures of comparative examples and examples of high-elasticity aluminum alloy casting materials according to one embodiment of the present invention.

[0024] FIG. 5 is an optical microscope photograph showing the effect of adding a refiner on the microstructure of a high-elasticity aluminum alloy casting according to one embodiment of the present invention.

[0025] FIG. 6 is an optical microscope photograph showing the effect of the content of the refiner TiB2 on the microstructure of a high-elasticity aluminum alloy casting according to one embodiment of the present invention.

[0026] Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0027] The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The following embodiments may be modified in various ways, and the scope of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to more faithfully and completely explain the present disclosure and to fully convey the spirit of the present invention to those skilled in the art. In addition, the thickness and size of each layer in the drawings are exaggerated for convenience and clarity of explanation.

[0028] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the present invention. As used herein, the singular forms "a," "an," and "the" include plural forms unless the context clearly dictates otherwise. Furthermore, when used herein, the words "comprise" and / or "comprising" specify the presence of stated features, numbers, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, components, and / or groups thereof.

[0029] Young's modulus is a value that represents the bonding force between atoms on a microscopic level. The stronger the bonding force between atoms, the higher the elastic modulus. It is an inherent property of the material. Aluminum alloys have a higher or similar specific modulus than gray cast iron and steel, but generally have a lower elastic modulus. Pure aluminum has an elastic modulus of about 69 GPa, and a specific modulus of about 25.5x10 6 m 2 / s 2 Among commercial aluminum alloy casting materials, the most widely used A356 (AC4C) alloy has an elastic modulus of about 75 GPa and a specific elastic modulus of about 28x10 6 m 2 / s2 Among commercial aluminum alloy casting materials, the A390 alloy with a large amount of silicon added has the highest elastic modulus of about 82 GPa and a specific elastic modulus of about 30x10 6 m 2 / s 2 On the other hand, gray cast iron has an elastic modulus of about 120 GPa and an inelastic modulus of about 16.7x10 6 m 2 / s 2 And steel has an elastic modulus of about 200 GPa and an inelastic modulus of about 25.5x10 6 m 2 / s 2 am.

[0030] It is difficult to change the elastic modulus of a material, and in the case of aluminum alloys, there is a method to improve the interatomic bonding by forming a solid solution, but it is not effective. Alternatively, the elastic modulus of the aluminum alloy can be increased by adding a ceramic reinforcement with a high elastic modulus or by forming an intermetallic compound with a high elastic modulus. That is, the elastic modulus can be increased when the aluminum alloy is formed into a metal matrix composite. Materials with added ceramic reinforcement with a high elastic modulus are aluminum-based metal matrix composites (MMCs). The aluminum-based metal matrix composites are materials that increase the elastic modulus of the material by adding a large amount of ceramic reinforcement with a high elastic modulus, such as SiC (about 450 GPa), TiC (about 400 GPa), or TiB2 (about 550 GPa), to an aluminum alloy. As the proportion of these ceramic reinforcements increases, the elastic modulus of the material increases. For example, aluminum-based metal matrix composites, which combine 20 vol% SiC with A359 aluminum alloy, have a high elastic modulus of approximately 104 GPa. However, aluminum-based metal matrix composites have low wettability between the aluminum molten metal and the ceramic particles, making them difficult to manufacture by casting, which may reduce economic feasibility. In addition, aluminum-based metal matrix composites contain very hard ceramic materials, so their processability is significantly poor and recycling is limited. Furthermore, there are problems such as deterioration of properties due to the reaction between the aluminum matrix and the reinforcement, and precipitation of ceramic materials during remelting. Therefore, the actual use of aluminum-based metal matrix composites is very limited.

[0031] According to the technical idea of ​​the present invention, by adding a large amount of alloying elements to aluminum to form various intermetallic compounds (IMCs) having a higher elastic modulus than aluminum, for example, by controlling the amount of alloying elements such as silicon (Si), nickel (Ni), copper (Cu), magnesium (Mg), titanium (Ti) or other transition metals, a high-elasticity aluminum alloy casting material having increased elastic modulus and specific elastic modulus can be provided.

[0032] Silicon and nickel are alloying elements that can be added to effectively increase the elastic and inelastic moduli of aluminum alloys. Copper, on the other hand, only slightly increases the elastic and inelastic moduli. Titanium, while increasing both moduli, can increase the melting point to over 1000°C when added in large quantities.

[0033] FIG. 1 is a phase diagram of a ternary alloy of aluminum-silicon-nickel for alloy design of a high-elasticity aluminum alloy casting material according to one embodiment of the present invention.

[0034] Referring to Figure 1, the melting point and the formed phases of the aluminum-silicon-nickel ternary alloy are shown. It can be seen that the melting point increases as the silicon content and nickel content increase, and in particular, the increase in the melting point due to the increase in silicon content is sharp. The formed phases in the aluminum-silicon-nickel ternary alloy are Al phase, Si phase, Al3Ni phase, and Al6Ni3Si phase. In the region where the silicon and nickel contents are low, they do not react with each other, but at 13 wt% silicon and 23.6 wt% nickel, they react to form the Al6Ni3Si phase, and as the nickel content increases, the range of silicon contents that form the Al6Ni3Si phase expands. For example, when the nickel content is 30 wt%, the Al6Ni3Si phase is formed at 10.5 wt% to 15.5 wt% silicon.

[0035] Taking this into account, thermodynamic calculations were performed on aluminum alloys containing 16 to 24 wt% silicon and 4 to 24 wt% nickel, to calculate the volume fractions of the resulting phases (Si phase, Al3Ni phase, Al6Ni3Si phase) generated in each composition. The aluminum alloy further contains 0.3 wt% magnesium and 0.15 wt% iron, and thus can be expressed as Al-xSi-yMg-0.3Mg-0.15Fe. Subsequently, the elastic modulus was calculated using the volume fractions of the resulting phases, and the specific elastic modulus was calculated by calculating the theoretical density.

[0036] Examining the calculated elastic modulus and inelastic modulus, the elastic modulus increases in the region where the Al6Ni3Si phase is formed, but the degree of increase decreases significantly, and the inelastic modulus decreases. This phenomenon is analyzed to be because when the Al6Ni3Si phase with an elastic modulus of approximately 175 GPa is formed, the amount of Al3Ni phase with a higher elastic modulus of approximately 187 GPa is produced, and the amount of Si phase (elastic modulus of approximately 162 GPa), which can increase both the elastic modulus and inelastic modulus, is produced decreases. Therefore, the composition range of silicon and nickel in which the Al6Ni3Si phase is not formed is analyzed to be an efficient composition range for producing a high-elasticity aluminum alloy.

[0037] In addition, the microstructural characteristics of the aluminum alloy are very important in order to secure excellent castability and brittleness resistance. When silicon is contained in an amount of 16 wt% or more and nickel in an amount of 4 wt% or more, primary Si and Al3Ni phases are formed in large quantities, and these phases need to be refined. In particular, the Al3Ni phase has an acicular or polygonal (blocky) shape depending on the silicon and nickel contents. It was confirmed that the acicular Al3Ni phase is refined by a refiner such as TiB2, but the polygonal Al3Ni phase is not refined. If the Al3Ni phase is formed coarsely, with a size of several hundred microns (μm), castability decreases and brittleness increases. Therefore, it is necessary to exclude a composition region in which a large amount of polygonal Al3Ni phase is formed. Similarly, it is also necessary to exclude a composition region in which primary silicon is coarsely grained.

[0038] When silicon is included in an amount exceeding 23 wt%, it was analyzed that the elastic modulus and the specific elastic modulus increase, but in this region, as shown in Fig. 1, the melting point of the aluminum alloy is high, and the proportion of primary Si having a size of 100 μm or more increases, resulting in a decrease in castability and an increase in brittleness.

[0039] As described above, it is necessary to control the contents of silicon and nickel contained in high-elasticity aluminum alloy castings to increase the elastic modulus and specific elastic modulus, improve castability, and reduce brittleness.

[0040] Hereinafter, a high-elasticity aluminum alloy casting material, which is one aspect of the present invention, will be described.

[0041] High-elasticity aluminum alloy casting material

[0042] A high-elasticity aluminum alloy casting material according to one embodiment of the present invention comprises: silicon (Si) in an amount exceeding 17.0 wt% to 23 wt%; nickel (Ni) in an amount exceeding 6.0 wt% to 18 wt%; magnesium (Mg) in an amount exceeding 0.2 wt% to 0.5 wt%; and the remainder being aluminum (Al) and other unavoidable impurities.

[0043] In addition, the high-elasticity aluminum alloy casting material may include 17.5 wt% to 20.5 wt% of silicon (Si); 7.5 wt% to 14.5 wt% of nickel (Ni); 0.2 wt% to 0.5 wt% of magnesium (Mg); and the remainder being aluminum (Al) and unavoidable impurities.

[0044] The high-elasticity aluminum alloy casting material may further contain, in addition to the above elements, for example, 2.0 wt% or less of copper (Cu), and may further contain, for example, more than 0 wt% to 2.0 wt% of copper. In addition, the high-elasticity aluminum alloy casting material may further contain, in addition to the above elements, 1.5 wt% or less of copper, and may further contain more than 0 wt% to 1.5 wt% of copper.

[0045] The high-elasticity aluminum alloy casting material may further include, in addition to the above elements, at least one of, for example, 0.3 wt% or less of chromium (Cr); 0.3 wt% or less of manganese (Mn); 0.2 wt% or less of titanium (Ti); and 0.2 wt% or less of zirconium (Zr). In addition, the high-elasticity aluminum alloy casting material may further include, in addition to the above elements, at least one of, for example, more than 0 wt% to 0.3 wt% of chromium (Cr); more than 0 wt% to 0.3 wt% of manganese (Mn); more than 0 wt% to 0.2 wt% of titanium (Ti); and more than 0 wt% to 0.2 wt% of zirconium (Zr).

[0046] The high-elasticity aluminum alloy casting material may further contain, in addition to the above elements, iron (Fe) of, for example, 0.5 wt% or less. In addition, the high-elasticity aluminum alloy casting material may further contain, in addition to the above elements, iron of, for example, more than 0 wt% to 0.5 wt%, or iron of more than 0 wt% to 0.35 wt%. The iron may be added as an additional element or included as an unavoidable impurity.

[0047] The above high-elasticity aluminum alloy casting material may further contain 0.003 wt% to 0.03 wt% (30 ppm to 300 ppm) of phosphorus (P). If the phosphorus is less than 0.003 wt% or more than 0.03 wt%, the refinement effect may be minimal. The phosphorus may be introduced into the aluminum molten metal in the form of AlP or AlCuP.

[0048] The above high-elasticity aluminum alloy casting material may further contain 0.02 wt% to 0.2 wt% (200 ppm to 2000 ppm) of TiB2. If the TiB2 is less than 0.02 wt% or more than 0.2 wt%, the refinement effect may be minimal. The TiB2 may be introduced into the aluminum molten metal in the form of an Al-TiB2 master alloy.

[0049] Hereinafter, the role and content of each component included in the high-elasticity aluminum alloy casting material according to the present invention will be described as follows.

[0050] Silicon (Si): More than 17 wt% to 23 wt%

[0051] Silicon has an elastic modulus of approximately 162 GPa, and exists as eutectic Si and primary Si, so it is an element that can increase the elastic modulus and inelastic modulus. When the silicon content is 17 wt% or less, the increase in the elastic modulus and inelastic modulus may be minimal. When the silicon content exceeds 23 wt%, the microstructure such as primary Si may coarsen, which may deteriorate castability, brittleness resistance, machinability, tensile properties, etc. Therefore, silicon may be added in an amount exceeding 17 wt% to 23 wt% of the total weight of the cast material. In addition, it is preferable that silicon be added in an amount of 17.5 wt% to 20.5 wt% of the total weight of the cast material.

[0052] Nickel (Ni): More than 6 wt% to 18 wt%

[0053] Nickel is an element that can increase the elastic modulus and inelastic modulus by forming an Al3Ni phase with an elastic modulus of approximately 187 GPa. When the nickel content is 6 wt% or less, the increase in the elastic modulus and inelastic modulus may be minimal. When the nickel content exceeds 18 wt%, the Al3Ni phase becomes coarse and forms a polygonal shape that is not refined, which reduces castability and deteriorates mechanical properties, and in particular, brittleness may increase due to a decrease in elongation. Therefore, nickel may be added in an amount exceeding 6 wt% to 18 wt% of the total weight of the cast material. In addition, nickel is preferably added in an amount of 7.5 wt% to 14.5 wt% of the total weight of the cast material.

[0054] Magnesium (Mg): 0.2 wt% to 0.5 wt%

[0055] Magnesium (Mg) can increase the hardness of the aluminum matrix by forming the Mg2Si phase. Since the aluminum matrix must have a certain level of hardness during machining of parts, containing magnesium is helpful in increasing the hardness. On the other hand, the Mg2Si phase has an elastic modulus of approximately 120 GPa, which is lower than the elastic modulus of primary Si and Al3Ni phases, and is therefore ineffective in increasing the elastic modulus. Therefore, adding a large amount of magnesium can actually decrease the elastic modulus by reducing the formation of the silicon phase, which helps improve the elastic modulus. When the magnesium content is less than 0.2 wt%, the effect of improving hardness may be minimal. When the magnesium content exceeds 0.5 wt%, the elastic modulus may decrease. Therefore, magnesium can be added in an amount of 0.2 wt% to 0.5 wt% of the total weight of the cast material.

[0056] Copper (Cu): 2.0 wt% or less

[0057] Copper (Cu) can increase the hardness of an aluminum matrix by forming an Al2Cu phase, an AlCuMg phase, or an AlCuMgSi phase. Since the aluminum matrix must have a certain level of hardness during machining of parts, containing copper is helpful in increasing the hardness. On the other hand, the Al2Cu phase or the AlCuMgSi phase has an elastic modulus of about 110 GPa to 120 GPa, which is lower than the elastic modulus of primary Si and Al3Ni phases, and is therefore ineffective in increasing the elastic modulus. Therefore, adding a large amount of copper can actually decrease the elastic modulus by reducing the formation of a silicon phase that helps improve the elastic modulus. In addition, the density increases depending on the copper content, which can also decrease the specific elastic modulus. When the copper content exceeds 2.0 wt%, the elastic modulus and the specific elastic modulus can decrease. Therefore, copper can be added in an amount of 2.0 wt% or less of the total weight of the casting material, and can be added in an amount of more than 0 wt% to 2.0 wt%. In addition, copper is preferably added in an amount of 1.5 wt% or less of the total weight of the casting material, and can be added in an amount of more than 0 wt% to 1.5 wt%, in order to optimize the elastic modulus and inelastic modulus.

[0058] Chromium (Cr): 0.3 wt% or less

[0059] Chromium (Cr) can increase the elastic modulus by forming an Al(Fe, Cr)Si phase. When the chromium content exceeds 0.3 wt%, the Al(Fe, Cr)Si phase coarsens, which reduces castability and deteriorates mechanical properties. In particular, brittleness may increase due to a decrease in elongation, and primary Si may coarsen. Therefore, chromium may be added in an amount of 0.3 wt% or less based on the total weight of the casting material, and may be added in an amount of more than 0 wt% to 0.3 wt%.

[0060] Manganese (Mn): 0.3 wt% or less

[0061] Manganese (Mn) can increase the elastic modulus by forming an Al(Fe, Mn)Si phase. When the manganese content exceeds 0.3 wt%, the Al(Fe, Mn)Si phase coarsens, which reduces castability and deteriorates mechanical properties. In particular, brittleness may increase due to a decrease in elongation, and primary Si may coarsen. Therefore, manganese may be added in an amount of 0.3 wt% or less based on the total weight of the cast material, and may be added in an amount of more than 0 wt% to 0.3 wt%.

[0062] Titanium (Ti): 0.2 wt% or less

[0063] Titanium (Ti) can increase the elastic modulus by forming an Al3Ti phase with an elastic modulus of approximately 215 GPa, and can also increase the inelastic modulus. However, titanium has a high melting point, so when a large amount is added, the temperature of the molten metal needs to be increased to 850°C or higher, and further, the melting point of the alloy can increase to 1000°C or higher. In particular, when silicon is contained in an amount of 12.6% or more, the AlSi(Ti) phase with a high elastic modulus of 200 GPa or higher can be formed in an Al-Si alloy, thereby increasing the elastic modulus of the aluminum alloy. However, it reduces the amount of primary Si phase formed, so it is not practically effective in increasing the elastic modulus. When the titanium content exceeds 0.2 wt%, there is a limit to the increase in the melting point. Therefore, titanium can be added in an amount of 0.2 wt% or less of the total weight of the cast material, and can be added in an amount of more than 0 wt% to 0.2 wt%.

[0064] Zirconium (Zr): 0.2 wt% or less

[0065] Zirconium (Zr) can increase the elastic modulus by forming the Al3Zr phase with an elastic modulus of approximately 215 GPa, and can also increase the inelastic modulus. However, zirconium has a high melting point, so when a large amount is added, the temperature of the melt needs to be increased to 850°C or higher, and further, the melting point of the alloy can increase to 1000°C or higher. In particular, when silicon is contained at 12.6% or more, the AlSi(Zr) phase with a high elastic modulus of 200 GPa or higher can be formed in the Al-Si alloy, which can increase the elastic modulus of the aluminum alloy. However, it reduces the amount of primary Si phase formed, so it is not practically effective in increasing the elastic modulus. When the zirconium content exceeds 0.2 wt%, there is a limit to the increase in the melting point. Therefore, zirconium can be added in an amount of 0.2 wt% or less of the total weight of the cast material, and can be added in an amount of more than 0 wt% to 0.2 wt%.

[0066] Iron (Fe): 0.5 wt% or less

[0067] Iron can increase the elastic modulus by forming AlFeSi phase, AlFeMgSi phase, etc., but it is lower than the elastic modulus of primary Si, Al3Ni phase, etc. In addition, when the amount of silicon or nickel added is large, the effect of increasing the elastic modulus is almost non-existent, and the specific elastic modulus decreases due to the increase in density. Therefore, iron may be contained as an unavoidable impurity in aluminum alloy castings. Therefore, it is preferable that iron is not contained in the aluminum alloy casting, or is limited to more than 0 wt% to 0.5 wt% of the total weight of the casting, or further, is limited to more than 0 wt% to 0.35 wt% of the total weight of the casting.

[0068] The remaining component of the above high-elasticity aluminum alloy casting material is aluminum (Al). However, during the typical manufacturing process, unintended impurities from raw materials or the surrounding environment can inevitably be mixed in, and thus cannot be excluded. Since these impurities are readily apparent to anyone skilled in the art of typical manufacturing, their full content is not specifically discussed in this specification.

[0069] The above high-elasticity aluminum alloy casting material may have a microstructure composed of primary Si and needle-like Al3Ni phases.

[0070] Below, the characteristics of the microstructure of a high-elasticity aluminum alloy casting were analyzed using a semi-quantitative method as follows.

[0071] The frequency (%) of polygonal Al3Ni phase and the frequency (%) of primary Si larger than 100 μm were calculated using the following method. First, the shapes of Al3Ni phase and primary Si were classified using three optical microscope photographs at 50x magnification for each composition, and the sizes and numbers were measured, which were expressed as frequencies using the following equations. The area of ​​the microstructure in the optical microscope photographs was approximately 6.81 mm. 2 It was.

[0072] The frequency (%) of the above polygonal Al3Ni phase was calculated by classifying the Al3Ni phase into needle-like and polygonal shapes and then using the following equation 1.

[0073] [Formula 1]

[0074] Frequency (%) of polygonal Al3Ni phase

[0075] = (Number of polygonal Al3Ni phases) / (Number of total Al3Ni phases) x 100

[0076] The above high-elasticity aluminum alloy casting material may have a microstructure in which the frequency of the polygonal Al3Ni phase is, for example, 28% or less, and may have a microstructure in which the frequency of the polygonal Al3Ni phase is, for example, 10% or less. When the frequency of the polygonal Al3Ni phase is 0%, it may be classified as “non-formed,” when the frequency of the polygonal Al3Ni phase is 10% or less, it may be classified as “trace-formed,” and when the frequency of the polygonal Al3Ni phase is more than 10%, it may be classified as “mass-formed.”

[0077] The frequency (%) of the primary Si having a major axis length of 100 μm or more was calculated using the following equation 2.

[0078] [Formula 2]

[0079] Frequency (%) of primary Si with a major axis length of 100 μm or more

[0080] = (Number of primary Si with a major axis length of 100 μm or more) / (Total number of primary Si) x 100

[0081] The above high-elasticity aluminum alloy casting material may have a microstructure in which the frequency of primary Si of the major axis length of 100 μm or more (i.e., the minimum value of the length of the longest side is 100 μm) is, for example, 8% or less, and may have a microstructure in which the frequency of primary Si of the major axis length of 100 μm or more is, for example, 6% or less. A frequency of primary Si of 0% to 2% or less in the major axis length of 100 μm or more may be classified as “fine,” a frequency of more than 2% to 6% or less may be classified as “slightly coarse,” and a frequency of 6% or more may be classified as “coarse.”

[0082] The above high-elasticity aluminum alloy casting material has an elastic modulus of 88 GPa to 120 GPa and an inelastic modulus of 32.5 x10 6 m 2 / s 2 ~ 40 x10 6 m 2 / s 2 can satisfy.

[0083] The high-elasticity aluminum alloy casting material may be heat treated after casting, for example, T6 heat treated after solution treatment and then aging treatment. Alternatively, the high-elasticity aluminum alloy casting material may be heat treated T5, which is aging treatment without solution treatment. The solution treatment may be performed by maintaining the material at a temperature ranging from 350°C to 550°C for 10 minutes to 10 hours, for example. The aging treatment may be performed by maintaining the material at a temperature ranging from 100°C to 250°C for 1 hour to 30 hours, for example. However, these temperatures and times are merely examples, and the technical idea of ​​the present invention is not limited thereto.

[0084] Hereinafter, the composition range and mechanical properties of the high-elasticity aluminum alloy casting material will be specifically described through experimental examples of the present invention.

[0085] Experimental example

[0086] Below, preferred experimental examples are presented to aid understanding of the present invention. However, these examples are provided solely to aid understanding of the present invention and are not intended to limit the present invention. Any details not described herein are technically feasible for those skilled in the art, and therefore, their description will be omitted.

[0087] According to the compositions in Table 1 below, pure metals or master alloys of aluminum, silicon, nickel, and magnesium were used and melted at 700°C to 850°C in a vacuum induction melting furnace in an argon atmosphere to form molten aluminum. The melt temperature varied depending on the alloy composition. After melting, the molten aluminum was poured into a mold preheated to 150°C to 350°C and cast, thereby producing a high-elasticity aluminum alloy casting. In addition, the case of performing sand casting is also included in the technical idea of ​​the present invention.

[0088] In addition, in order to refine the phase formed during melting of aluminum alloy, AlP master alloy (100 ppm to 200 ppm based on P content) and Al-TiB2 master alloy (600 ppm to 1200 ppm based on TiB2) were added. For comparison, alloys were also manufactured without adding P and TiB2 or with adding large amounts of P and TiB2.

[0089] The manufactured aluminum alloy casting material was processed into test specimens measuring 40 mm x 15 mm x 3 mm. The dynamic Young's modulus of the test specimens was measured using the impulse excitation technique (ASTM E1876-01). In addition, the density of the test specimens was measured to calculate the inelastic modulus.

[0090] The microstructure of the above high-elasticity aluminum alloy casting material was observed using an optical microscope.

[0091] Table 1 is a table showing the alloy composition and content of comparative examples and examples of high-elasticity aluminum alloy casting materials of the present invention. The alloy composition in Table 1 refers to weight percent (wt%), and the remainder of all alloys includes aluminum and other unavoidable impurities.

[0092] Classification SiNiMgFePTiB2 Comparative Example 1 16 120.30.15 0.020.075 Comparative Example 2 16 160.30.15 0.020.075 Comparative Example 3 16 200.30.15 0.020.075 Comparative Example 4 18 40.30.15 0.020.075 Comparative Example 5 18 200.30.15 0.020.075 Comparative Example 6 18 240.30.15 0.020.075 Comparative Example 7 22 140.30.15 0.020.075Comparative Example 8246.20.30.150.020.075Comparative Example 92480.30.150.020.075Comparative Example 1024100.30.150.020.075Comparative Example 1124120.30.150.020.075Comparative Example 1224140.30.150.020.075Example 1186.20.30.150.020.075Example 21880.30.150.0 20.075Embodiment 3 18 100.30.150.020.075Embodiment 4 18 120.30.150.020.075Embodiment 5 18 140.30.150.020.075Embodiment 6 18 160.30.150.020.075Embodiment 7 18 180.30.150.020.075Embodiment 8 206.20.30.150.020.075Embodiment 9 2080.30.150.020.075 Example 10 20 100.30.15 0.020.075 Example 11 20 120.30.15 0.020.075 Example 12 20 140.30.15 0.020.075 Example 13 20 180.30.15 0.020.075 Example 14 22 80.30.15 0.020.075 Example 15 22 100.30.15 0.020.075 Example 16 22 120.30.15 0.020.075

[0093] Figure 2 is a graph illustrating the composition of silicon and nickel for comparative examples and examples of high-elasticity aluminum alloy castings according to one embodiment of the present invention. In Figure 2, "non" means a comparative example, and "real" means an example.

[0094] Referring to Table 1 and Fig. 2, in the high-elasticity aluminum alloy casting material, iron (Fe) is not intentionally added but is included as an unavoidable impurity, and phosphorus (P) and TiB2 are added as particle refiners.

[0095] Comparative Examples 1 to 3 differ in that the silicon content is 16 wt%, which is less than the lower limit of the scope of the present invention. In addition, Comparative Example 3 differs in that the nickel content exceeds the upper limit of the scope of the present invention.

[0096] Comparative Examples 4 to 7 include silicon within the scope of the present invention. Comparative Example 4 differs in that it includes nickel below the lower limit of the scope of the present invention. Comparative Examples 5 to 7 differ in that it includes nickel above the upper limit of the scope of the present invention.

[0097] Comparative Examples 8 to 12 differ in that the silicon content is 24 wt%, which exceeds the upper limit of the scope of the present invention, and nickel is included within the scope of the present invention.

[0098] The composition range of the high-elasticity aluminum alloy casting material according to an embodiment of the present invention corresponds to the area inside the pentagon ABCDE of Fig. 2. Here, A represents 17 wt% Si and 6 wt% Ni, B represents 17 wt% Si and 18 wt% Ni, C represents 20 wt% Si and 18 wt% Ni, D represents 23 wt% Si and 10 wt% Ni, and E represents 23 wt% Si and 6 wt% Ni. The line CD is as shown in Equation 3 below.

[0099] [Formula 3]

[0100] Ni [wt%] = (214 - 8 x Si [wt%]) / 3

[0101] Therefore, when the content of the silicon is in the range of 20 wt% to 23 wt%, the correlation between the content of the silicon and the content of the nickel can satisfy the following equation 4.

[0102] [Formula 4]

[0103] Ni [wt%] ≤ (214 - 8 x Si [wt%]) / 3

[0104] FIGS. 3 and 4 are optical microscope photographs showing the microstructures of comparative examples and examples of high-elasticity aluminum alloy casting materials according to one embodiment of the present invention.

[0105] Referring to Fig. 3, the microstructure of Comparative Example 6 (Al-18Si-24Ni-0.3Mg-0.15Fe) included primary Si, acicular Al3Ni phase, and blocky Al3Ni phase. On the other hand, the microstructure of Example 6 (Al-18Si-16Ni-0.3Mg-0.15Fe) included primary Si and acicular Al3Ni phase, but did not include blocky Al3Ni phase.

[0106] Referring to Fig. 4, in Comparative Examples 1, 3, and 5, a large amount of blocky Al3Ni phase was formed, as indicated by arrows. In addition, in Comparative Example 9, coarse primary Si having a length exceeding 100 μm was formed unevenly, as indicated by arrows.

[0107] As the silicon content increased, the size of the primary Si increased, and the Al3Ni phase changed from a needle-like shape to a polygonal shape, or the needle-like shape became coarse. When the silicon content was 16 wt%, the Al3Ni phase mostly had a polygonal shape, and when the silicon content was 18 wt% or more and the nickel content was low, the Al3Ni phase appeared as needles, and as the nickel content increased, there was a tendency for more polygonal Al3Ni phases to be formed. When the silicon content was 24 wt% or more, the Al3Ni phase was formed as coarse needles, and the size of the primary Si also became coarse. Therefore, the silicon content is preferably in the range of more than 17.0 wt% to 23 wt%.

[0108] When the nickel content increases in the range of silicon content exceeding 17.0 wt% to 23 wt%, the Al3Ni phase tends to change from needle-like to polygonal in shape, or the needle size becomes coarse. In particular, when the nickel content exceeds 18 wt%, the needle-like Al3Ni phase becomes coarse. Considering the elastic modulus, it is preferable that the nickel content exceeds 6 wt%. Therefore, the nickel content is preferably in the range of 6.0 wt% to 18 wt%.

[0109] In the range of silicon content exceeding 17.0 wt% to 23 wt% and nickel content exceeding 6.0 wt% to 18 wt%, in the region of high silicon and nickel contents, the microstructure became coarse and the melting point of the aluminum alloy was high at 760°C or higher. When the melting point of the aluminum alloy is high, the hydrogen concentration of the molten metal increases, which may increase the occurrence of pores inside the specimen during casting. Therefore, it is desirable to satisfy the correlation between the silicon content and the nickel content of the above equation 2.

[0110] Table 2 is a table showing the mechanical properties and microstructure of the high-elasticity aluminum alloy casting material of Table 1 according to one embodiment of the present invention.

[0111] Classification Elastic modulus (GPa) Specific elastic modulus (x10 6 , m 2 / s 2 ) Density (g / cm) 3) Polygonal shape Al3Ni phase frequency (%) Major axis length 100 μm or more Primary Si frequency (%) Comparative example 195.6 32.94 2.90 130.80 Comparative example 299.6 33.65 2.96 033.8 2.8 Comparative example 3 107.2 35.5 33.01 833.92.7 Comparative example 4 86.7 32.08 2.70 300 Comparative example 5 110.13 5.9 13.06 6 29.31.6 Comparative example 6 116.2 36.60 3.17 4 28.53.6 Comparative example 7 104.8 36.2 32.893011.4Comparative Example895.034.992.71408.3Comparative Example997.635.462.75208.1Comparative Example10100.235.992.7850.88.4Comparative Example11103.036.442.826015.5Comparative Example12106.837.362.8581.411.6Example189.932.812.73900Example292.233. 092.78700Example 396.033.822.83700Example 499.134.422.87800Example 5100.634.742.89700Example 6105.335.442.9720.80Example 7109.736.333.0191.30Example 892.933.962.73601.2Example 994.934.412.75701.1Example 1 097.234.462.82201.4Example 1199.435.052.83601.5Example 12101.235.402.86001.1Example 13111.537.083.0081.01.2Example 1496.635.022.75800.8Example 1599.235.402.80201.5Example 16102.336.032.8400.61.0

[0112] Referring to Table 2, the elastic modulus, inelastic modulus, and density are shown as mechanical properties, and the frequency (%) of polygonal Al3Ni phase and the frequency (%) of primary Si of 100 μm or more are shown as microstructures.

[0113] In Comparative Examples 1 to 3, the elastic modulus and specific elastic modulus satisfied the range of the present invention. Since a large amount of polygonal Al3Ni phases were produced, and their frequency was about 30% or more, they did not satisfy the range of the present invention. The primary Si had an overall uniform and fine shape, and the frequency of primary Si of 100 μm or more was about 3% or less.

[0114] In Comparative Example 4, the elastic modulus and specific elastic modulus were lower than the lower limit of the scope of the present invention, and thus, the scope of the present invention was not satisfied. Since the frequency of the polygonal Al3Ni phase was approximately 0%, it is analyzed that the polygonal Al3Ni phase was not formed. The primary Si had an overall uniform and fine shape, and the frequency of primary Si of 100 μm or more was approximately 0%.

[0115] In Comparative Examples 5 and 6, the elastic modulus and specific elastic modulus satisfied the range of the present invention. Since a large amount of polygonal Al3Ni phase was generated and its frequency was about 28% or more, it did not satisfy the range of the present invention. The primary Si had an overall uniform and fine shape, and the frequency of primary Si of 100 μm or more was about 4% or less.

[0116] In Comparative Examples 7 to 12, the elastic modulus and specific elastic modulus satisfied the range of the present invention. The polygonal Al3Ni phase was not formed or its frequency was about 1.5% or less. The primary Si had an uneven and coarse shape, and the frequency of primary Si of 100 μm or more exceeded about 8%, thus not satisfying the range of the present invention.

[0117] Therefore, it is analyzed that the comparative examples will not provide the required castability and brittleness resistance because the polygonal Al3Ni phase is generated at a frequency of 28% or more, or the primary Si has an uneven and coarse shape, and the frequency of the primary Si of 100 μm or more is about 8% or more.

[0118] In the examples, the elastic modulus and inelastic modulus satisfied the range of the present invention. In addition, the primary Si had a uniform and fine shape, and the frequency of primary Si larger than 100 μm was found to be about 2% or less. The polygonal Al3Ni phase was not formed or was found to have a frequency of about 1.5% or less. Therefore, the examples are analyzed to provide high elastic modulus and inelastic modulus while simultaneously providing the required castability and brittleness resistance.

[0119] Hereinafter, the influence of iron content in a high-elasticity aluminum alloy casting material according to the technical idea of ​​the present invention will be examined.

[0120] Table 3 is a table showing the alloy composition and content of examples in which the iron content was varied in the high-elasticity aluminum alloy casting material of the present invention. The alloy composition in Table 3 refers to weight percent, and the remainder of all alloys includes aluminum and other unavoidable impurities.

[0121] Classification SiNiMgFePTiB2 Example 17 186.20.30.30.020.075 Example 18 18100.30.30.020.075 Example 19 18120.30.30.020.075 Example 20 186.20.30.50.020.075 Example 21 18100.30.50.020.075 Example 22 18120.30.50.020.075

[0122] Referring to Table 3, in the examples, the contents of silicon, nickel, and magnesium are within the scope of the present invention. In the examples, the contents of iron are 0.3 wt% and 0.5 wt%, which are increased compared to 0.15 wt% in Table 1.

[0123] Table 4 is a table showing the mechanical properties and microstructure of the high-elasticity aluminum alloy casting material of Table 3 according to one embodiment of the present invention.

[0124] Classification Elastic modulus (GPa) Specific elastic modulus (x10 6 , m 2 / s 2 ) Density (g / cm) 3 )Frequency (%) of polygonal shape Al3Ni phaseFrequency (%) of primary Si with a major axis length of 100 μm or moreExample 1790.532.942.74900Example 1896.134.012.82400Example 1999.534.652.87200Example 2091.533.262.75200Example 2196.634.232.82200Example 2298.634.482.86000

[0125] Referring to Table 4, the elastic modulus and inelastic modulus of the examples in which the iron content was increased to 0.5 wt% or less satisfied the scope of the present invention. The elastic modulus and inelastic modulus showed a tendency to increase somewhat as the iron content increased. In addition, since the frequency of the polygonal Al3Ni phase was about 0%, it is analyzed that the polygonal Al3Ni phase was not formed. The primary Si had an overall uniform and fine shape, and the frequency of the primary Si of 100 μm or more was about 0%. Therefore, it is preferable that the iron content of the high-elasticity aluminum alloy casting material be 0.5 wt% or less.

[0126] Hereinafter, the influence of additional elements in a high-elasticity aluminum alloy casting material according to the technical idea of ​​the present invention will be examined.

[0127] A high-elasticity aluminum alloy casting material further containing one of copper, manganese, and chromium was manufactured using the above-described method.

[0128] Table 5 is a table showing the alloy composition and content of an example of a high-elasticity aluminum alloy casting material of the present invention that further includes additional elements such as copper, manganese, and chromium. The alloy composition in Table 5 refers to weight percent, and the remainder in all alloys includes aluminum and other unavoidable impurities.

[0129] ClassificationSiNiMgFeCuMnCrPTiB2Example 231880.30.150.5000.020.075Example 241880.30.151000.020.075Example 251880.30.152000.020.075Example 2618100.30.151000.020.075Example 2718100.30.152000. 020.075 Example 28 20100.30.15 1000.020.075 Example 29 20100.30.15 2000.020.075 Example 30 20100.30.15 00.25 00.020.075 Example 31 20100.30.15 000.25 0.020.075 Example 32 20100.50.15 0000.020.075

[0130] Referring to Table 5, silicon, nickel, and magnesium are included in the scope of the present invention in the examples. Examples 23 to 29 further include copper, Example 30 further includes manganese, Example 31 further includes chromium, and Example 32 has a magnesium content of 0.5 wt%, which is an increase from 0.3 wt% in Table 1.

[0131] Table 6 is a table showing the mechanical properties and microstructure of the high-elasticity aluminum alloy casting material of Table 5 according to one embodiment of the present invention.

[0132] Classification Elastic modulus (GPa) Specific elastic modulus (x10 6 , m 2 / s 2 ) Density (g / cm) 3) Polygonal shape Al3Ni phase frequency (%) Primary Si with a major axis length of 100 μm or more Frequency (%) Example 2 393.9 33.5 0 2.80 200 Example 2 494.133.5 12.80 900 Example 2 592.333.0 32.79 400 Example 2 696.0 33.8 32.83 600 Example 2 796.6 33.7 82.85 800 Example 2 8100.335.4 0 2.83 30 1.6 Example 2 999.0 34.5 9 2.86 20 1.7 Example 3 0102.4 35.6 7 2.87 102.7 Example 3 199.9 35.0 8 2.84 60 4.9 Example 3 296.7 34.2 4 2.82 50 1.4

[0133] Referring to Table 6, the elastic modulus and specific elastic modulus in all cases where copper was further included in an amount of 2 wt% or less, manganese was further included in an amount of 0.25 wt%, chromium was further included in an amount of 0.25 wt%, or magnesium was included in an amount of 0.5 wt% satisfied the range of the present invention. In addition, in all cases, the frequency of the polygonal Al3Ni phase was approximately 0%, so it was analyzed that the polygonal Al3Ni phase was not formed. The primary Si had an overall uniform and fine shape, and the frequency of primary Si of 100 μm or more was approximately 5% or less.

[0134] As the copper content increases, the elastic modulus tends to increase, but the elastic modulus and inelastic modulus tend to decrease at a copper content of 2 wt% compared to a copper content of 1 wt%. Therefore, the copper content of the high-elasticity aluminum alloy casting material may be 2.0 wt% or less, and for optimization of the elastic modulus and inelastic modulus, it is preferably 1.5 wt% or less.

[0135] When manganese and chromium are included, it is analyzed that the elastic modulus and specific elastic modulus increase, but the frequency of primary Si particles larger than 100 μm increases. Therefore, it is preferable that the content of chromium is 0.3 wt% or less, and the content of manganese is 0.3 wt% or less.

[0136] Even when the magnesium content was increased to 0.5 wt%, there was little change in the elastic modulus, inelastic modulus, and microstructure. Therefore, it is preferable that the magnesium content be 0.5 wt% or less.

[0137] Hereinafter, the influence of a refiner on a high-elasticity aluminum alloy casting material according to the technical idea of ​​the present invention will be examined.

[0138] In Al-Si-Ni alloys, it is desirable to add an additional refiner together with phosphorus (P) to refine the formed phase, such as Al3Ni, in addition to the primary Si to improve castability and tensile properties. The refiner can be selected based on a critical value of lattice misfit between the formed phase and the refiner based on crystallographic theory, for example, the edge-to-edge model (Bramfitt model). The refiner must satisfy the crystallographic critical value and have a higher melting point than the formed phase.

[0139] In the high-elasticity aluminum alloy casting material of the present invention, in the Al-Si-Ni composition range where Al3Ni exists in a needle-like state, primary Si and Al3Ni phases are formed in large quantities. If the primary Si and Al3Ni phases are coarse, castability, machinability, tensile properties, etc. may deteriorate. Therefore, refinement of the formed phases does not significantly affect the elastic modulus, but can improve castability, brittleness resistance, machinability, tensile properties, etc.

[0140] FIG. 5 is an optical microscope photograph showing the effect of adding a refiner on the microstructure of a high-elasticity aluminum alloy casting according to one embodiment of the present invention.

[0141] Referring to FIG. 5, based on the content of 18Si-8Ni-0.3Mg-0.15Fe-0.5Cu of Example 23, the microstructures of the case where phosphorus (P) and TiB2 are not included as a refiner (Case 1), the case where only 0.02 wt% phosphorus (P) is included without TiB2 (Case 2), the case where only 0.075 wt% TiB2 is included without phosphorus (P) (Case 3), and the case where both 0.02 wt% phosphorus (P) and 0.075 wt% TiB2 are included (Case 4) (Example 23) are shown.

[0142] When analyzing the mechanical properties, the elastic modulus was 92.8 GPa (Case 1), 93.0 GPa (Case 2), 93.3 GPa (Case 3), and 93.9 GPa (Case 4) in the above order, and the specific elastic modulus was 33.14x10 in the above order. 6 m 2 / s 2 (Case 1), 33.38x10 6 m 2 / s 2 (Case 2), 33.32x10 6 m 2 / s 2 (Case 3), and 33.50x10 6 m 2 / s 2 (Case 4) As shown in the figure, it is analyzed that the addition of a finer agent has little effect on the elastic modulus and inelastic modulus.

[0143] When analyzing the microstructure, the polygonal Al3Ni phase was not formed in all cases. In the case where the phosphorus (P) and the TiB2 were not included (Case 1), the primary Si had an uneven and coarse shape, the frequency of primary Si of 100 μm or more was 23.5%, and the needle-like Al3Ni phase appeared coarse. In the case where only the phosphorus (P) was included without the TiB2 (Case 2), the primary Si was formed as a uniform and fine phase, but the needle-like Al3Ni phase appeared coarse. In the case where the phosphorus (P) was not included and only the TiB2 was included (Case 3), the primary Si had an uneven and coarse shape, the frequency of primary Si of 100 μm or more was 12.9%, and the needle-like Al3Ni phase appeared fine. When the above-mentioned P and TiB2 were included together (Case 4), the primary Si was formed as a uniform and fine phase, and the needle-like Al3Ni phase also appeared finely.

[0144] Based on these results, it is analyzed that the phosphorus content makes the primary Si uniform and fine, and the TiB2 content refines the needle-like Al3Ni phase. Therefore, as a refiner, it is preferable to add the phosphorus and the TiB2 together. The phosphorus content is preferably in the range of 0.003 wt% to 0.03 wt%, and the TiB2 content is preferably in the range of 0.02 wt% to 0.2 wt%. Here, a case in which at least one of MgAl2O4, NbB2, and AlB2 is included instead of the TiB2 is also included in the technical idea of ​​the present invention.

[0145] FIG. 6 is an optical microscope photograph showing the effect of the content of the refiner TiB2 on the microstructure of a high-elasticity aluminum alloy casting according to one embodiment of the present invention.

[0146] Referring to FIG. 6, the microstructures are shown when, based on the content of Example 23, 18Si-8Ni-0.3Mg-0.15Fe-0.5Cu, 0.02 wt% of phosphorus is further included and the amount of TiB2 added is changed to 0 wt% (0 ppm) (Case 5), 0.075 wt% (750 ppm) (Case 6), 0.15 wt% (1500 ppm) (Case 7), and 0.22 wt% (2200 ppm) (Case 8).

[0147] When the amount of TiB2 added was 0.075 wt% (Case 6) and 0.15 wt% (Case 7), the micronization effect was prominent, but when the amount of TiB2 added was 0 wt% (Case 5) and 0.22 wt% (Case 8), the micronization effect was minimal.

[0148] Therefore, in order to refine both the super-crystalline Si and the needle-like Al3Ni phases, it is preferable to add 0.003 wt% to 0.03 wt% of phosphorus and 0.02 wt% to 0.2 wt% of TiB2 together.

[0149] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent alternative embodiments are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

[0150] According to one embodiment of the present invention as described above, a high-elasticity aluminum alloy casting material can be used to produce an aluminum casting alloy that is lightweight and has a high elastic modulus and specific elastic modulus, and thus can be applied to the production of aluminum casting parts for automobiles, machine parts, etc. that require excellent elasticity and rigidity.

Claims

More than 17.0 wt% to 23 wt% silicon (Si); More than 6.0 wt% to 18 wt% nickel (Ni); 0.2 wt% to 0.5 wt% magnesium (Mg); and The remainder contains aluminum (Al) and unavoidable impurities. High elasticity aluminum alloy casting material.

2. In paragraph 1, When the content of the silicon is in the range of 20 wt% to 23 wt%, the correlation between the content of the silicon and the content of the nickel satisfies the following equation: Ni [wt%] ≤ (214 - 8 x Si [wt%]) / 3 High elasticity aluminum alloy casting material.

3. In paragraph 1, 17.5 wt% to 20.5 wt% silicon (Si); 7.5 wt% to 14.5 wt% nickel (Ni); 0.2 wt% to 0.5 wt% magnesium (Mg); and The remainder contains aluminum (Al) and unavoidable impurities. High elasticity aluminum alloy casting material.

4. In paragraph 1, Further comprising not more than 1.5 wt% copper (Cu), High elasticity aluminum alloy casting material.

5. In paragraph 1, Chromium (Cr) not more than 0.3 wt%; Manganese (Mn) of not more than 0.3 wt%; less than 0.2 wt% titanium (Ti); and At least one of zirconium (Zr) of 0.2 wt% or less is further included. High elasticity aluminum alloy casting material.

6. In paragraph 1, Further containing 0.5 wt% or less of iron (Fe), High elasticity aluminum alloy casting material.

7. In paragraph 1, 0.003 wt% to 0.03 wt% phosphorus; and Further comprising 0.02 wt% to 0.2 wt% of TiB2, High elasticity aluminum alloy casting material.

8. In paragraph 1, 0.003 wt% to 0.03 wt% phosphorus; and Further comprising at least one of TiB2, MgAl2O4, NbB2, and AlB2 as a refiner in an amount of 0.02 wt% to 0.2 wt%. High elasticity aluminum alloy casting material.

9. In paragraph 1, Having a microstructure composed of super-crystalline Si and needle-like Al3Ni phases, High elasticity aluminum alloy casting material.

10. In paragraph 1, Elastic modulus: 88 GPa ~ 120 GPa and inelastic modulus: 32.5 x10 6 m 2 / s 2 ~ 40 x10 6 m 2 / s 2 Satisfying, High elasticity aluminum alloy casting material.

11. In paragraph 1, Having a microstructure with a frequency of less than 10% on polygonal Al3Ni, High elasticity aluminum alloy casting material.

12. In paragraph 1, Having a microstructure with a frequency of primary Si of 6% or less and a major axis length of 100 μm or more, High elasticity aluminum alloy casting material.

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