Aluminum alloy, method for manufacturing additively formed objects, and additively formed objects

Abstract

To provide an aluminum alloy having improved ductility.SOLUTION: An aluminum alloy is used in additive manufacturing, the aluminum alloy containing Si, Fe, Mn and inevitable impurities, in which α-phase Al-Si-Fe intermetallic compounds are present.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an aluminum alloy used for additive manufacturing, a method for manufacturing an additive manufactured object, and an additive manufactured object.

Background Art

[0002] A method for manufacturing an additive manufactured object of an aluminum alloy using a metal 3D printer is known. At this time, the process of spreading aluminum alloy powder and irradiating a specific part with a laser beam or an electron beam to dissolve the aluminum alloy powder and then solidify it is repeated.

[0003] In order to improve the mechanical strength of an additive manufactured object of an aluminum alloy, for example, it is described that one or more of Mn and Cr are added to an aluminum alloy containing Si and Fe which is an inevitable impurity (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, it is desired to improve the mechanical strength of an additive manufactured object using an aluminum alloy containing a large amount of inexpensive Fe.

[0006] Here, an aluminum alloy containing Si and Fe has a problem that the ductility of the aluminum alloy decreases because a β-phase Al-Si-Fe-based intermetallic compound (Al5FeSi) grows during manufacturing. The β-phase Al-Si-Fe-based intermetallic compound has a monoclinic crystal structure, is plate-shaped (the cross section is needle-shaped), and is brittle.

[0007] The present invention aims to provide an aluminum alloy capable of improving ductility. [Means for solving the problem]

[0008] One aspect of the present invention is an aluminum alloy used in additive manufacturing, comprising Si, Fe, Mn, and unavoidable impurities, wherein an α-phase Al-Si-Fe intermetallic compound exists.

[0009] The above-mentioned aluminum alloy may have a Si content of 3% to 20% by mass, a Fe content of 0.5% to 7% by mass, and a Mn content of 0.1% to 7% by mass.

[0010] The above aluminum alloy may further contain Be or Zr.

[0011] The above aluminum alloy may have a Be content of 0.05% by mass or more and 1% by mass or less, and a Zr content of 0.2% by mass or more and 5% by mass or less.

[0012] The above aluminum alloy may further contain Cu, Zn, Mg, Ti, and Ni.

[0013] Another aspect of the present invention is a method for manufacturing an additively manufactured object, wherein additive manufacturing is performed using the above-mentioned aluminum alloy powder.

[0014] Another aspect of the present invention is an additively fabricated aluminum alloy as described above. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an aluminum alloy that can improve ductility. [Brief explanation of the drawing]

[0016] [Figure 1] This figure shows the X-ray diffraction spectra of aluminum alloys from Examples 1-1, 1-2, and Comparative Example 1. [Figure 2] SEM photographs of the surfaces of the test pieces of Comparative Example 1 and Examples 1-1 and 1-2 before the tensile test. [Figure 3] SEM photographs of the surfaces of the test pieces of Comparative Example 1 and Examples 1-1 and 1-2 after the tensile test.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0018] [Aluminum alloy] The aluminum alloy of the present embodiment contains Si, Fe, Mn, and inevitable impurities, and an α-phase Al-Si-Fe-based intermetallic compound (Al 15 Fe3Si2) is present. Since the aluminum alloy of the present embodiment has an α-phase Al-Si-Fe-based intermetallic compound, the growth of the β-phase Al-Si-Fe-based intermetallic compound is suppressed. As a result, the ductility of the aluminum alloy of the present embodiment is improved. Here, the α-phase Al-Si-Fe-based intermetallic compound has a cubic crystal structure and is granular. Further, when the aluminum alloy of the present embodiment contains Zn, the corrosion resistance of the aluminum alloy of the present embodiment is improved. Furthermore, an aluminum secondary alloy ingot containing a large amount of impurities such as Fe and Zn can be used as a raw material for the aluminum alloy of the present embodiment. The aluminum secondary alloy ingot is a material with a low environmental load because the amount of CO2 emissions during production is small.

[0019] Note that the aluminum alloy of the present embodiment is used for additive manufacturing.

[0020] The content of Si in the aluminum alloy of the present embodiment is 3% by mass or more and 20% by mass or less, and preferably 5% by mass or more and 15% by mass or less. When the content of Si in the aluminum alloy of the present embodiment is 3% by mass or more, cracking of the aluminum alloy of the present embodiment is less likely to occur, and when it is 20% by mass or less, solidification cracking of the aluminum alloy of the present embodiment is less likely to occur.

[0021] The content of Fe in the aluminum alloy of this embodiment is 0.5% by mass or more and 7% by mass or less, preferably 1% by mass or more and 3% by mass or less. When the content of Fe in the aluminum alloy of this embodiment is 0.5% by mass or more, the mechanical strength of the aluminum alloy of this embodiment is improved, and when it is 7% by mass or less, the ductility of the aluminum alloy of this embodiment is improved.

[0022] The content of Mn in the aluminum alloy of this embodiment is 0.1% by mass or more and 7% by mass or less, preferably 0.5% by mass or more and 2% by mass or less. When the content of Mn in the aluminum alloy of this embodiment is 0.1% by mass or more and 7% by mass or less, the ductility of the aluminum alloy of this embodiment is improved.

[0023] The aluminum alloy of this embodiment may further contain Be or Zr. Thereby, the growth of the β-phase Al-Si-Fe-based intermetallic compound is further suppressed.

[0024] The content of Be in the aluminum alloy of this embodiment is preferably 0.05% by mass or more and 1% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less. When the content of Be in the aluminum alloy of this embodiment is 0.05% by mass or more and 1% by mass or less, the ductility of the aluminum alloy of this embodiment is improved.

[0025] The content of Zr in the aluminum alloy of this embodiment is preferably 0.2% by mass or more and 5% by mass or less, and more preferably 0.4% by mass or more and 2.0% by mass or less. When the content of Zr in the aluminum alloy of this embodiment is 0.2% by mass or more and 5% by mass or less, the ductility of the aluminum alloy of this embodiment is improved.

[0026] The above aluminum alloy may further contain Cu, Zn, Mg, Ti, and Ni.

[0027] The form of the aluminum alloy in this embodiment is not particularly limited, but examples include ingots, powders, rods, plates, etc.

[0028] Ingots can be manufactured, for example, by melting a base alloy above its melting point to create molten metal, and then pouring the molten metal into an iron mold.

[0029] Furthermore, it is preferable to perform a degassing treatment when manufacturing ingots.

[0030] The powder can be produced, for example, by crushing an ingot.

[0031] [Method for manufacturing additively fabricated objects] The manufacturing method for the additively fabricated object of this embodiment involves additive fabrication using the aluminum alloy powder of this embodiment.

[0032] For example, using a metal 3D printer, the aluminum alloy powder of this embodiment is spread to a thickness of 1 μm or more, and a laser beam or electron beam is irradiated onto a specific area to heat the powder to a temperature above its melting point and melt it. Then, the molten powder is cooled at a rate of 1 × 10⁻¹⁰ 4 The process of solidifying at temperatures above °C / s is repeated.

[0033] [Laminated fabricated objects] The additively manufactured product of this embodiment is an additively manufactured product of the aluminum alloy of this embodiment, and is manufactured by the manufacturing method of the additively manufactured product of this embodiment. Therefore, the additively manufactured product of this embodiment has improved ductility and mechanical strength.

[0034] The applications of the additively manufactured products of this embodiment are not particularly limited, but examples include aluminum parts for automobiles. [Examples]

[0035] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0036] [Examples 1-1, 1-2, Comparative Example 1] A base alloy having a predetermined composition (see Table 1) was melted at a temperature above its melting point to produce molten metal. This molten metal was then poured into an iron mold to produce an aluminum alloy ingot. During the production of the aluminum alloy ingot, a degassing treatment was performed.

[0037] [Crystal structure analysis] The crystal structure of aluminum alloys was analyzed using a horizontal-type high-power X-ray diffractometer, Rint TTRIII (manufactured by Rigaku). CuKα rays were used as the characteristic X-rays. The samples were prepared by cutting aluminum alloy ingots into 10 cm squares with a thickness of 1 to 10 mm, and then polishing the surfaces with 1000-grit sandpaper and a buffing wheel.

[0038] Figure 1 shows the X-ray diffraction spectra of aluminum alloys from Examples 1-1, 1-2, and Comparative Example 1.

[0039] Figure 1 shows that the aluminum alloys of Examples 1-1 and 1-2 contain α-phase Al-Si-Fe intermetallic compounds, whereas the aluminum alloy of Comparative Example 1 does not contain α-phase Al-Si-Fe intermetallic compounds.

[0040] [Tensile test] Tensile tests were conducted using a precision universal testing machine AGX-V (manufactured by Shimadzu Corporation) in accordance with ISO 6892-1 or JIS Z 2241 to measure the elongation of aluminum alloys. JIS No. 4 test specimens were used, and the elongation of the specimens was measured using an extensometer (N=4).

[0041] Table 1 shows the evaluation results of the elongation of the aluminum alloys in Examples 1-1, 1-2, and Comparative Example 1.

[0042] [Table 1]

[0043] Table 1 shows that the aluminum alloys of Examples 1-1 and 1-2 have greater elongation, i.e., higher ductility, than the aluminum alloy of Comparative Example 1.

[0044] [SEM observation] The surface of the test specimens before and after tensile testing was observed using a scanning electron microscope SU6600 (manufactured by Hitachi).

[0045] Figures 2 and 3 show SEM images of the surface of the specimens of Comparative Example 1 and Examples 1-1 and 1-2 before and after the tensile test, respectively.

[0046] Figure 2 shows that the specimen of Comparative Example 1 before the tensile test shows the growth of needle-shaped intermetallic compounds (regions enclosed by lines), i.e., β-phase Al-Si-Fe intermetallic compounds. In contrast, the specimens of Examples 1-1 and 1-2 before the tensile test show the presence of granular intermetallic compounds (regions enclosed by lines), i.e., α-phase Al-Si-Fe intermetallic compounds, and the growth of β-phase Al-Si-Fe intermetallic compounds is suppressed.

[0047] Figure 3 shows that the specimen of Comparative Example 1 after tensile testing has more brittle fracture surfaces (regions enclosed by lines) than the specimens of Examples 1-1 and 1-2 after tensile testing. Therefore, it can be seen that the β-phase Al-Si-Fe intermetallic compound contributes to the brittle fracture surfaces.

[0048] [Examples 2-1 to 2-4, Comparative Example 2] An aluminum alloy ingot was prepared in the same manner as in Example 1-1, except that the composition of the master alloy was changed (see Table 2).

[0049] [Crystal structure analysis] As mentioned above, analysis of the crystal structure of the aluminum alloys revealed that the aluminum alloys of Examples 2-1 to 2-4 contained α-phase Al-Si-Fe intermetallic compounds, while the aluminum alloy of Comparative Example 2 did not contain α-phase Al-Si-Fe intermetallic compounds.

[0050] [Tensile test] As mentioned earlier, tensile tests were conducted on the aluminum alloy.

[0051] Table 2 shows the evaluation results of the elongation of the aluminum alloys in Examples 2-1 to 2-4 and Comparative Example 2.

[0052] [Table 2]

[0053] Table 2 shows that the aluminum alloys of Examples 2-1 to 2-4 have greater elongation, i.e., higher ductility, than the aluminum alloy of Comparative Example 2.

[0054] [Examples 3-1 to 3-4, Comparative Example 3] An aluminum alloy ingot was prepared in the same manner as in Example 1-1, except that the composition of the master alloy was changed (see Table 3).

[0055] [Crystal structure analysis] As mentioned above, analysis of the crystal structure of the aluminum alloys revealed that the aluminum alloys of Examples 3-1 to 3-4 contained α-phase Al-Si-Fe intermetallic compounds, while the aluminum alloy of Comparative Example 3 did not contain α-phase Al-Si-Fe intermetallic compounds.

[0056] [Tensile test] As mentioned earlier, tensile tests were conducted on the aluminum alloy.

[0057] Table 3 shows the evaluation results of the elongation of the aluminum alloys in Examples 3-1 to 3-4 and Comparative Example 3.

[0058] [Table 3]

[0059] Table 3 shows that the aluminum alloys of Examples 3-1 to 3-4 have greater elongation, i.e., higher ductility, than the aluminum alloy of Comparative Example 3.

Claims

1. An aluminum alloy used in additive manufacturing, It consists only of Al, Si, Fe, Mn, Be, and unavoidable impurities. An α-phase Al-Si-Fe intermetallic compound exists, The Si content is 3% by mass or more and 15% by mass or less. The Fe content is 0.5% by mass or more and 3% by mass or less. The Mn content is 0.1% by mass or more and 2% by mass or less. An aluminum alloy having a Be content of 0.05% by mass or more and 1% by mass or less.

2. An aluminum alloy used in additive manufacturing, It consists only of Al, Si, Fe, Mn, Cu, Zn, Mg, Ti, Ni, and unavoidable impurities. An α-phase Al-Si-Fe intermetallic compound exists, The Si content is 3% by mass or more and 15% by mass or less. The Fe content is 0.5% by mass or more and 3% by mass or less. The Mn content is 0.1% by mass or more and 2% by mass or less. The Cu content is 0.26% by mass. The Zn content is 0.48% by mass. The Mg content is 0.4% by mass. The Ti content is 0.02% by mass. An aluminum alloy with a Ni content of 0.025% by mass.

3. A method for manufacturing an additively manufactured product, comprising additive manufacturing using the aluminum alloy powder described in claim 1 or 2.

4. An additively fabricated aluminum alloy product according to claim 1 or 2.

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