Aluminum-based composition, aluminum alloy powder, aluminum alloy additive manufactured product, method for forming aluminum alloy powder, and method for manufacturing additive manufactured product.

Abstract

An aluminum-based composition comprising aluminum, magnesium, copper, chromium, silicon, scandium, and zirconium, further comprising one or more other metals other than aluminum, magnesium, copper, chromium, scandium, and zirconium. Based on the total amount of the aluminum-based composition, scandium is present in an amount of 0.46 mass% to 0.80 mass%, and zirconium is present in an amount of 0.15 mass% to 0.40 mass%.

Description

[Technical Field]

[0001] This invention relates to the formation of powder chemical compositions and processing conditions for powder gas atomization to achieve crack-free medium-strength and high-strength aluminum alloy powders and components.

[0002] The present invention further relates to the control of the microstructure and properties of Al6xxx powder, a medium-strength aluminum alloy developed for additive manufacturing. [Background technology]

[0003] Medium-strength and high-strength aluminum alloys play important roles in the aerospace, automotive, and semiconductor industries. These alloys include Al-Cu(2xxx), Al-Mg-Si(6xxx), and Al-Zn(7xxx) alloys. Laser powder bed fusion (LPBF) treatment of these aluminum alloys remains challenging due to crack formation. To address the solidification cracking problem, two main approaches have been employed: (1) optimization of treatment parameters and (2) modification of the powder's chemical composition.

[0004] (1) Optimization of processing parameters:

[0005] Cracks observed in LPBF high-strength aluminum alloys are primarily due to thermal cracking located at grain boundaries. To eliminate solidification cracking, a type of thermal cracking commonly seen in additively fabricated medium-strength and high-strength aluminum alloys, adjustment of processing parameters is usually the first step. By adjusting the LPBF processing parameters, the cooling rate, temperature gradient, and solidification rate are controlled. This is intended to reduce stress between interdendritic regions or increase the liquid backfill capacity in the semi-molten zone, thereby strengthening crack resistance.

[0006] Scanning speed is the most common LPBF treatment parameter to optimize. The correlation between scanning speed and crack susceptibility has been widely studied. Conclusions from the literature indicate that crack susceptibility increases with increasing scanning speed. Therefore, reducing the scanning speed is one of the common methods to eliminate cracks during LPBF treatment. This method has been successful with Al2xxx alloys such as Al-Cu-Mg and Al2195, but not with Al6xxx and Al7xxx alloys.

[0007] In addition to scanning speed, another approach to solving the cracking problem is to increase the preheating temperature. Increasing the preheating temperature reduces the cooling rate during the solidification process, which prevents cracking. A preheating temperature of 500°C has been shown to successfully solve the cracking problem in Al6061 alloys because it reduces solidification supercooling. However, in the case of Al7075 alloys, it has been reported that preheating the baseplate during printing does not eliminate cracking. On the contrary, this may lead to more serious cracking in the sample. While preheating at 500°C can effectively address the cracking problem in Al6061 alloys, it should be noted that this temperature requirement presents significant difficulties due to the limited capabilities of most commercially available LPBF instruments. Therefore, this hinders the implementation of this approach.

[0008] Furthermore, hatch spacing and defocus distance have been proven to be contributing factors to crack formation in Al-Cu alloys. The effect of defocus distance on crack formation in Al7050 has also been studied, but the cracking problem remains unresolved. Therefore, optimizing treatment parameters to eliminate cracks during LPBF treatment is more effective in Al-Cu alloys than in Al-Mg-Si alloys or Al-Zn alloys.

[0009] (2) Changes to the chemical composition of Al powder:

[0010] The concept of modifying the chemical composition of a powder to resolve cracking problems involves introducing secondary particles to refine the grain size. By introducing elements such as Sc and Zr, nucleation sites can be formed before α-Al solidification. Refining the grain size can prevent crack formation / propagation and enhance grain boundary strengthening. Compared to coarse columnar particles, fine equiaxed grains are more effective in eliminating cracks for the following reasons: (1) Fine equiaxed grains make crack propagation more difficult than with columnar particles. (2) Fine equiaxed grains increase the critical stress for thermal cracking and delay the onset of dendrite coherence. The particle refinement efficiency of the introduced inoculant depends on lattice mismatch.

[0011] This method has been reported for a wide range of aluminum alloys in LPBF, including Al-Cu-Mg, Al-Mn-Mg, and Al-Zn. A commercially available powder using this method is Scalmalloy®, which contains Sc and Zr in a medium-strength Al-Mg alloy. Derived alloys of Scalmalloy®, such as Addalloy® (Al-Mg-Zr), are also being studied. As an Al7xxx alloy, 7A77.60L alloy (Al-Zn-Mg-Cu-Zr) is also commercially available. Its yield strength (YS) is 490-585 MPa, its ultimate tensile strength (UTS) is 520-615 MPa, and its elongation is 6-14%.

[0012] Information in the literature is very limited regarding derivative alloys of the two most common medium-strength and high-strength aluminum alloys, Al6061 and Al7075. AlZnMgScZr alloys produced in LPBF have been reported to achieve yield strengths (YS) of 418.3 MPa and ultimate tensile strengths (UTS) of 425.7 MPa, respectively, after T6 heat treatment. An AlZnMgCuScZr alloy produced in LPBF with a YS of 647 MPa has also been reported. Airbus has also filed intellectual property rights in the EU, covering a very wide range of chemical compositions.

[0013] In addition to the information above, Elementum 3D has introduced ceramics into Al6061 and Al7050 alloys for LPBF treatment. Both alloys contain 2% ceramic. For Al6061 containing 2% ceramic, the YS and UTS after T6 treatment are 297±14MPa and 331±20MPa, respectively, with an elongation of 12±1.5%. When 2% ceramic is added to Al7050, the YS and UTS after HIP treatment and T74 treatment are 469±3MPa and 504±3MPa, respectively, with an elongation of 6±1.5%. However, details of the ceramics have not been reported.

[0014] Furthermore, powder quality is crucial for achieving optimal, crack-free strength in LPBF Al6061 and Al7075 components. However, there is no documented literature regarding the correlation between the gas atomization (GA) process of powders and the resulting powder quality (chemical composition, morphology, size distribution, and yield of GA powder). [Overview of the Initiative]

[0015] To realize crack-free medium-strength and high-strength aluminum alloy powders, and additively manufactured products using such alloy powders, the present invention includes, in some embodiments, the following items.

[0016] Item 1: An aluminum-based composition comprising aluminum, magnesium, copper, chromium, silicon, scandium, zirconium, and one or more other metals other than aluminum, magnesium, copper, chromium, scandium, and zirconium, wherein, based on the total amount of the aluminum-based composition, scandium is present in an amount of 0.46 mass% to 0.80 mass%, and zirconium is present in an amount of 0.15 mass% to 0.40 mass%.

[0017] Item 2: A composition according to Item 1, wherein scandium is present in an amount of 0.46 mass% to 0.72 mass% and zirconium is present in an amount of 0.15 mass% to 0.36 mass% based on the total amount of the aluminum-based composition.

[0018] Item 3: A composition according to Item 1, wherein magnesium is present in an amount of 0.8 mass% to 1.4 mass% based on the total amount of the aluminum-based composition.

[0019] Item 4: A composition according to Item 3, wherein magnesium is present in an amount of 0.8 mass% to 1.2 mass% based on the total amount of the aluminum-based composition.

[0020] Item 5: A composition according to Item 1, wherein copper is present in an amount of 0.15 mass% to 0.4 mass% based on the total amount of the aluminum-based composition.

[0021] Item 6: A composition according to Item 1, wherein chromium is present in an amount of 0.04 mass% to 0.45 mass% based on the total amount of the aluminum-based composition.

[0022] Item 7: A composition according to Item 6, wherein chromium is present in an amount of 0.04 mass% to 0.35 mass% based on the total amount of the aluminum-based composition.

[0023] Item 8: A composition according to Item 1, wherein silicon is present in an amount of 0.4 mass% to 1.0 mass% based on the total amount of the aluminum-based composition.

[0024] Item 9: A composition according to Item 8, wherein silicon is present in an amount of 0.4 mass% to 0.8 mass% based on the total amount of the aluminum-based composition.

[0025] Item 10: A composition according to Item 1, further comprising zinc present in an amount of less than 0.25 mass% based on the total amount of the aluminum-based composition.

[0026] Item 11: A composition according to Item 1, wherein one or more other metals include iron, manganese, and / or titanium.

[0027] Item 12: A composition according to Item 11, wherein iron is present in an amount of less than 0.2 mass%, and manganese and titanium are present in an amount of less than 0.3 mass%, based on the total amount of the aluminum-based composition.

[0028] Item 13: A composition according to Item 12, wherein iron is present in an amount of less than 0.2 mass%, and manganese and titanium are present in an amount of less than 0.15 mass%, based on the total amount of the aluminum-based composition.

[0029] Item 14: An aluminum-based composition comprising aluminum, zinc, magnesium, copper, chromium, scandium, zirconium, and one or more other metals other than aluminum, zinc, magnesium, copper, chromium, scandium, and zirconium, wherein, based on the total amount of the aluminum-based composition, scandium is present in an amount of 0.35 mass% to 1.04 mass% and zirconium is present in an amount of 0.15 mass% to 0.52 mass%.

[0030] Item 15: A composition according to Item 14, in which zinc is present in an amount of 5.5 mass% to 7.0 mass% based on the total amount of the aluminum-based composition.

[0031] Item 16: A composition according to Item 14, in which magnesium is present in an amount of 2.3 mass% to 3.2 mass% based on the total amount of the aluminum-based composition.

[0032] Item 17: A composition according to Item 14, wherein copper is present in an amount of 1.2 mass% to 2.0 mass% based on the total amount of the aluminum-based composition.

[0033] Item 18: A composition according to Item 14, wherein chromium is present in an amount of 0.28 mass% or less based on the total amount of the aluminum-based composition.

[0034] Item 19: A composition according to Item 14, further comprising silicon present in an amount of less than 0.2 mass% based on the total amount of the aluminum-based composition.

[0035] Item 20: A composition according to Item 14, wherein one or more other metals include iron, manganese, titanium, nickel, lead, tin, and / or vanadium.

[0036] Item 21: A composition according to Item 15, wherein, based on the total amount of the aluminum-based composition, iron is present in an amount of less than 0.2 mass%, manganese and titanium are present in an amount of 0.1 mass% or less each, nickel and lead are present in an amount of 0.01 mass% or less each, and tin and vanadium are present in an amount of less than 0.01 mass% each.

[0037] Item 22: A composition according to Item 15, further comprising oxygen present in an amount of less than 0.03 mass%, nitrogen present in an amount of less than 0.01 mass%, and hydrogen present in an amount of 0.001 mass%, based on the total amount of the aluminum-based composition.

[0038] The elements listed in items 1 to 22 can be combined as appropriate without including conflicting characteristics. For example, one embodiment includes all of items 1 to 3, 5 to 6, 8, and 10 to 12. Another embodiment includes all of items 1 to 2, 4, 5, 7, 9 to 11, and 13. And yet another embodiment includes all of items 14 to 22. Other combinations are also possible and may be adjusted by those skilled in the art.

[0039] Item 23: An aluminum-based composition comprising magnesium, copper, chromium, silicon, scandium, zirconium, and one or more other metals other than aluminum, magnesium, copper, chromium, scandium, and zirconium, with the remainder being aluminum with unavoidable impurities, wherein scandium is present in an amount of 0.46 mass% to 0.80 mass% and zirconium is present in an amount of 0.15 mass% to 0.40 mass% based on the total amount of the aluminum-based composition. The one or more other metals are selected from the group consisting of iron, manganese, and / or titanium.

[0040] Item 24: A composition comprising any one of items 1 to 23, wherein the composition is aluminum alloy powder.

[0041] Item 25: A composition comprising any one of items 1 to 23, wherein the composition is an aluminum alloy additively manufactured product.

[0042] Item 26: A method for forming aluminum alloy powder, comprising: inductively melting an aluminum-based composition according to Item 1 to produce a molten aluminum alloy; and treating the molten aluminum alloy by a gas atomization method.

[0043] Item 27: The method according to Item 26, wherein the gas atomization method is carried out with (i) a pressure of 40–45 bar, (ii) a power of 20–30 kW, and / or (iii) a temperature of 60°C–100°C.

[0044] Item 28: The method according to Item 26, wherein the aluminum alloy powder is free from cracks.

[0045] Item 29: A method for forming an aluminum alloy powder, comprising: inductively melting an aluminum-based composition according to Item 14 to produce a molten aluminum alloy; and treating the molten aluminum alloy by a gas atomization method.

[0046] Item 30: The method according to Item 29, wherein the gas atomization method is carried out at (i) a pressure of 40–45 bar, (ii) a power of 20–30 kW, and / or (iii) a temperature of 60°C–100°C.

[0047] Item 31: The method according to Item 29, wherein no cracks are present in the aluminum alloy powder.

[0048] Item 32: A method for additively manufacturing a product, comprising forming an additively manufactured product using aluminum alloy powder according to Item 24 as a raw material powder for additive manufacturing.

[0049] Item 33: A method according to Item 32, wherein the additive manufacturing is a powder bed fusion method using an electron beam or laser, or a directed energy deposition method using an electron beam or laser.

[0050] By using the above-mentioned aluminum-based composition to form aluminum alloy powder and to form additively manufactured products (or laminated molded products or bulk products), the resulting products are crack-free and exhibit yield strength, tensile strength, and elongation within the desired range. [Brief explanation of the drawing]

[0051] [Figure 1] This shows the relationship between the mole fraction of the solids Al5.5Zn2.3Mg1.2Cu and Al5.5Zn2.3Mg1.2Cu0.28Cr and temperature. [Figure 2] This shows the calculated effect of Sc on the critical cooling rate of Al7xxx. The orange dashed line represents the critical cooling rate = 1 × 10⁶ K / s. [Figure 3] This shows the calculated effect of Sc on the critical cooling rate of Al6xxx. The orange dashed line represents the critical cooling rate = 5 × 10⁵ K / s. [Figure 4] This shows the particle size distribution of Al6xxx with different Sc and Zr content during the GA process. [Figure 5] This shows the particle size distribution of Al7xxx with different Sc and Zr content during the GA process. [Figure 6] (a) represents the yield (%) of the gas atomization process of atomized Al6xxx using different gas pressures and (b) different heating powers. [Figure 7] (a) Represents the particle size (μm) of Al6xxx powder atomized using different gas pressures and (b) different heating powers. [Figure 8] (a) shows the particle size distribution of atomized Al6xxx powder using heating power of 25kW, (b) 22kW, and (c) 20kW. [Figure 9] This graph shows the effect of heating power on the powder form of atomized Al6xxx powder. [Figure 10] This image shows a typical scanning electron microscope (SEM) image of atomized Al6xxx powder. [Figure 11] This shows (a) yield (%) and (b) particle size (μm) of Al7xxx atomized powder using different heating power levels. [Figure 12] (a) shows the particle size distribution of atomized Al7xxx powder using heating power of 22kW, (b) 25kW, and (c) 28kW. [Figure 13] This graph shows the effect of heating power on the powder form of atomized Al7xxx powder. [Figure 14] This image shows a typical SEM image of atomized Al7xxx powder. [Figure 15] This EBSD result shows that ultrafine particles are insufficient in samples printed using Zr-deficient GA powder. [Figure 16] This diagram illustrates the general configuration of laser additive manufacturing. [Figure 17] This is a microscopic image of additively manufactured part B1. [Figure 18] This is a microscopic image of additively manufactured part B2. [Figure 19] This is a microscopic image of additively manufactured part B3. [Figure 20] This is a microscopic image of additively manufactured part B4. [Figure 21] This is a microscopic image of a B5-sized additively manufactured product. [Figure 22] This shows the microstructure of the sample from Example E1. [Figure 23] This shows the microstructure of the sample from Example E2. [Figure 24] This shows the TEM results of the DA sample from Example E3. [Figure 25] This shows the TEM results of the STA sample from Example E4. [Modes for carrying out the invention]

[0052] In this invention, the expression "mass%" represents weight percentage, or simply weight%. The mass% described in one or more examples of this invention is based on the total amount (100%) of the aluminum-based composition.

[0053] In some embodiments, the present invention includes the following items (1) to (3):

[0054] (1) Chemical compositions for two types of aluminum alloys: Al6xxx (medium strength / weight %: Zn<0.25, Mg 0.8~1.4, Si 0.4~1.0, Cu 0.15~0.4, Cr 0.04~0.45, Sc 0.46~0.8, Zr 0.15~0.4, Fe<0.2, Mn<0.3, Ti<0.3, others total ≤0.15) alloy and Al7xxx (high strength / (Weight %): Zn 5.5~7, Mg 2.3~3.2, Cu 1.2~2.0, Cr 0~0.28, Sc 0.35~1.04, Zr 0.15~0.52, Fe<0.2, Si<0.2, Mn≦0.1, Ti≦0.1, Ni≦0.01, Pb≦0.01, Sn<0.01, V<0.01, O<0.03, N<0.01, H<0.001, Others total ≦0.15) Alloy.

[0055] (2) Electrode-induced dissolution inert gas atomization (EIGA) process for producing powders suitable for additive manufacturing processes: (Power: 20-25 kW, Gas pressure: 45 bar).

[0056] (3) A laminated product in which aluminum alloy powder obtained by the EIGA process is used as raw material powder for additive manufacturing (AM), wherein the additive manufacturing is performed by powder bed fusion (PBF) using an electron beam or laser, or directed energy deposition (DED) using an electron beam or laser.

[0057] The above chemical compositions are modified based on Al6061 and Al7075 alloys. The composition of Sc and Zr is crucial to eliminate cracking in Al6xxx and Al7xxx alloys between both the GA and LPBF processes. The lower limits of Sc and Zr depend on whether Al3(Sc,Zr) can nucleate before the solidification of α-Al that occurs during the process. Based on time-dependent nucleation theory, the nucleation incubation time can be calculated by equation (1):

number

number

number

number

[0058] Density and temperature were calculated using Thermo-Calc software with the TCAL8 database. Al5.5Zn2.3Mg1.2Cu and Al0.9Mg0.4Si0.2Cu were selected as representatives of the original Al6061 and Al7075. It was first demonstrated that the effect of Cr has little effect on crack initiation. Figure 1 shows the relationship between the mole fraction of the solid and temperature, showing that increasing Cr from 0% to 0.28% has little effect on the α-Al nucleation temperature.

[0059] For more favorable thermal stability, a weight percentage ratio of Sc:Zr of 2:1 is selected. Figure 2 shows the calculated effect of Sc on the critical cooling rate of Al7xxx. As the Sc content increases, the critical cooling rate increases. In the LPBF process of aluminum alloys, the cooling rate of the molten pool at the edge of the molten pool boundary of the aluminum alloy is 10 5 ~10 6 The cooling rate reaches K / s. The cooling rate increases as you approach the center of the molten pool. In Al7xxx, which is very sensitive to crack initiation, it is necessary to form equiaxed grain regions not only at the edges of the molten pool. Therefore, the critical cooling rate is 1 × 10⁻⁶. 6 Select K / s. The lower limits for Sc and Zr in Al7xxx are 0.40% and 0.20%, respectively.

[0060] Figure 3 shows the calculated effect of Sc on the critical cooling rate of Al6xxx. Since Al6xxx has lower crack susceptibility compared to Al7xxx, the critical cooling rate is 5 × 10⁻⁶. 5 Select K / s. The lower limits for Sc and Zr in Al6xxx are 0.46% and 0.23%, respectively.

[0061] The upper limit depends on the size of the Al3(Sc,Zr) phase. If the radius of Al3Sc is greater than 40 nm, the matching relationship with the matrix changes to semi-matched, and the efficiency of functioning as a nucleation site is lost. Phase growth can be calculated according to the Lifshitz-Slyozov-Wagner theory.

number

number

[0062] The calculation results for the upper limits of Al6xxx and Al7xxx are shown in Figures 4 and 5, respectively. Based on the above, the proposed chemical composition of the present invention is as shown in Table 1. The proposed chemical composition has a narrower range compared to the chemical composition of Airbus IP.

[0063] Table 1: Proposed chemical compositions of Al6xxx and Al7xxx

[0064] [Table 1] JPEG2026517559000017.jpg61160

[0065] In Table 1, reference [1] refers to "Zhou, L., Pan, H., Hyer, H., Park, S., Bai, Y., McWilliams, B., Cho, K., & Sohn, Y. (2019). Microstructure and tensile property of a novel AlZnMgScZr alloy additively manufactured by gas atomization and laser powder bed fusion. Scripta Materialia, 158, 24-28." Furthermore, reference [2] is “Zhu, Z., Ng, FL, Seet, HL, Lu, W., Liebscher, CH, Rao, Z., Raabe, D., & Nai, SML (2022). Superior mechanical properties of a selective-laser-melted AlZnMgCuScZr alloy enabled by a tunable hierarchical microstructure and dual-nanoprecipitation. Materials Today, 52, 90-101”.

[0066] Electrode-induced dissolution inert gas atomization (EIGA) is a powder atomization method that enables the production of spherical, low-porosity metal powders with minimal oxygen pickup. This atomization method is suitable for producing powders of both reactive and non-reactive metal materials, and the quality of the produced powder is effectively usable for additive manufacturing (AM). EIGA equipment is used to finen the Al6xxx and Al7xxx alloys designed for this purpose.

[0067] The atomization process is controlled by two main parameters: (1) atomization power and (2) atomization gas pressure. For Al6xxx alloys, the atomization powers used were 20, 22, and 25 kW, and the atomization gas pressures used were 35, 40, and 45 bar. In addition, to prevent backflow of molten material, the pressure difference between the chamber and the tower must be maintained at over 120 mbar. The electrode length used was a maximum of 500 mm, and the diameter was 50 mm. Other parameters included a gas temperature of 80°C and a nozzle gap of 0.66-0.68 mm.

[0068] Figure 6 shows the effect of gas pressure and heating power on the yield of the gas atomization process, which is determined by the weight of the original electrode, the total weight of the atomized powder, and the weight of the powder sieved to less than 150 μm. As the gas pressure increases, the sieved yield improves significantly, but the effect of heating power is minimal. Figure 7 shows the effect of gas pressure and heating power on the particle size distribution (powder particle size). The particle size distribution of the aluminum alloy powder of the present invention is obtained by a laser diffraction particle size distribution analyzer. In the cumulative distribution curve showing the relationship between particle size and volume cumulative distribution from the smallest particle size side, particle size D10 corresponding to a cumulative frequency of 10 volume%, particle size D50 corresponding to a cumulative frequency of 50 volume%, and particle size D90 corresponding to a cumulative frequency of 90 volume% are measured. Figure 7 shows that the powder particle size is 43 μm to 75 μm for D50, 17 μm to 31 μm for D10, and 82 μm to 142 μm for D90. As gas pressure increases, particle size decreases. The powder particle size distribution is almost unaffected by heating power. Figure 8 shows the particle size distribution of powder atomized at a gas pressure of 45 bar. More than 67% of the atomized powder is in the range of 20-63 μm, which is suitable for LPBF. Figure 9 shows the effect of heating power on the powder morphology. The results show that there is no significant effect from heating power within the test range. More than 70% of the powder is spherical. Therefore, a heating power of 20-25 kW and a gas pressure of 45 bar are suitable for this process. Figure 10 shows an SEM image of the powder, representing the sphericity of the powder. The chemical composition of the atomized powder and the additively manufactured product (or printed coupon) is shown in Table 2.

[0069] Table 2: Chemical composition of proposed Al6xxx powder, gas atomized (GA) powder, and laser powder bed fusion (LPBF) additively manufactured parts

[0070] [Table 2]

[0071] For Al7xxx alloys, the atomization powers used were 22, 25, and 28 kW, and the atomization gas pressure used was 45 bar. In addition, to prevent backflow of molten material, the pressure difference between the chamber and the tower must be maintained at over 120 mbar. Other parameters included a gas temperature of 80°C and a nozzle gap of 0.66–0.68 mm.

[0072] Figure 11 shows the effect of heating power on yield and particle size distribution (powder particle size). The effect of heating power on sieved yield and particle size is minimal. However, it was observed that powder atomized at less than 28 kW showed a lower sieved yield. Figure 12 shows the particle size distribution (powder particle size). Approximately 50% of the atomized powder was in the range of 20-63 μm, suitable for LPBF. Figure 13 shows the effect of heating power on powder morphology. The results show that there is no significant effect of heating power within the test range. More than 70% of the powder is spherical. Therefore, heating power of 20-25 kW and gas pressure of 45 bar are suitable for this process. Figure 14 shows an SEM image of the powder, representing the sphericity of the powder. The chemical composition of the atomized powder is shown in Table 3. The experimental chemical composition is slightly outside the range of the proposed chemical composition. The Sc content is equal to the lower limit of the proposed composition, while the Zr content is lower than the lower limit of the proposed composition. The lack of Zr suggests poor particle refinement capability. Figure 15 shows the EBSD results of a sample printed using powder at an ultra-low scanning speed (low cooling rate). Insufficient ultrafine particles demonstrate poor particle refinement capability, which is associated with crack formation. This result indicates that the presence of appropriate Sc / Zr in the powder is essential, ensuring the production of crack-free samples through the LPBF process.

[0073] Table 3: Chemical composition of proposed Al7xxx and GA Al7xxx powders [Table 3] JPEG2026517559000020.jpg61160

[0074] An alloy powder having the above composition is prepared as the raw material for the additively manufactured product according to this embodiment. The chemical composition of the additively manufactured product is basically the same as the chemical composition of the alloy powder.

[0075] An embodiment of the additive manufacturing method using the alloy powder described above as a raw material will be described. The additive manufacturing method according to the present invention is a method for manufacturing additively manufactured products by the following steps, which include irradiating the Al-based alloy powder with an electron beam or laser beam to melt and solidify it in order to construct an additively manufactured product. One of its features is that the powder sample is irradiated with an electron beam or laser beam to melt and solidify it.

[0076] Figure 16 shows a schematic configuration of a laser additive manufacturing method that uses a laser as a heat source to perform additive manufacturing in powder bed fusion. As shown in Figure 16, 1 is the alloy powder used as raw material, 2 is the powder feeder, 3 is the coating blade, 4 is the laser oscillator, 5 is the laser beam, 6 is the galvanometer equipment, 7 is the manufactured part (additive-built part), and 8 is the build platform.

[0077] In the additive manufacturing method, alloy powder 1 is supplied onto the build plate 8 by raising the powder supply plate 2 by a predetermined distance, lowering the build plate 8 by a predetermined distance, and moving the coating blade 3 in the X direction. The laser beam 5 from the laser oscillator 4 is controlled by a galvanometer device 6 and irradiated onto the alloy powder in the supply area, causing the alloy powder to selectively melt and solidify to form a solidified layer. By repeating this process, a three-dimensional construct part 7 (additive-manufactured part) is constructed.

[0078] Embodiments in which products are constructed by irradiating them with an electron beam or laser beam to melt and solidify them are applicable to both the PBF bonding method and the DED method, which are additive manufacturing methods (referred to as AM methods in this invention) for metal materials.

[0079] The additive manufacturing method of the present invention, using the PBF method as an example, may include the following steps:

[0080] Step 1: An optional preheating step in which the base plate is heated to a preheating temperature in the range of 25°C to 200°C in order to preheat the alloy powder (e.g., aluminum alloy powder) spread on the base plate. In some embodiments, the preheating temperature is preferably in the range of 50°C to 200°C, and more preferably in the range of 100°C to 200°C.

[0081] Step 2: Additive manufacturing step, in which alloy powder spread on a base plate is irradiated with a heat source to selectively melt and solidify the alloy powder in order to form a solidified layer, and this step is repeated to construct an additively manufactured product.

[0082] Step 3: An optional post-processing step, such as a heat treatment step, in which a heat treatment process is performed on the additively manufactured part under specific conditions.

[0083] The additive manufacturing method of the present invention uses a laser or electron beam as the heat source for the powder bed fusion method in the additive manufacturing step (step 2). In some embodiments, the conditions for the additive manufacturing step may be, for example, an electron beam output or laser output of 50 to 1,000 W, a scanning speed of 100 to 5,000 mm / s, and a scanning interval of 0.05 to 0.5 mm to form a layer thickness of 0.01 to 0.1 mm. For the purpose of improving molding accuracy or preventing unmelted Al alloy powder, the demonstration conditions include a layer thickness of 20 to 50 μm, an electron beam output or laser output of 100 to 500 W, a scanning speed of 600 to 1,200 mm / s, and a scanning interval of 0.05 to 0.12 mm.

[0084] In some embodiments, by using an additive manufacturing method including at least steps 1 and 2 described above, the resulting additively manufactured product has the following mechanical properties. For example, the tensile strength in the X-Y direction is not particularly limited and may be 290 MPa or more. For example, the yield strength in the XY direction is not particularly limited and may be 265 MPa or more, with an upper limit of 300 MPa for the yield strength. For example, the elongation in the XY direction is not particularly limited and may be 10% or more, with an upper limit of 25% for the elongation. In some embodiments, the porosity of the resulting additively manufactured product is 2.0% or less, preferably 1.0%, and more preferably 0.5%.

[0085] In some embodiments, the additively manufactured product obtained by using an additive manufacturing method including at least steps 1 and 2 described above has the following physical properties. For example, the thermal conductivity (W / (m·K)) is between 100 (W / m·K) and 120 (W / m·K) at room temperature, in the range of 120 to 140 (W / m·K) at 100°C, in the range of 130 to 150 (W / m·K) at 200°C, and in the range of 140 to 170 (W / m·K) at 300°C.

[0086] In some embodiments, an optional post-treatment step / heat treatment step (step 3) includes a heat treatment process such as direct aging (DA) at a temperature in the range of 250°C to 450°C for 5 minutes to 100 hours. In some other embodiments, an optional heat treatment step (step 3) includes a heat treatment process such as solution aging (STA), which includes solution treatment at a high temperature (460 to 550°C) for 5 minutes to 10 hours, water quenching, and aging at a low temperature (140 to 220°C) for 30 minutes to 100 hours.

[0087] In some embodiments, when a neutral salt spray (NSS) test is measured in accordance with ISO 9227 (JIS Z 2371), the corrosion loss value (g / m²) is measured. 2 ) is 4.5g / m 2 The following characteristics are observed, and it has performance equivalent to that of the conventional material A6061.

[0088] Example:

[0089] In the following examples, five types of aluminum alloy powder samples (P1 to P5) were prepared, and five types of additive manufacturing product samples (B1 to B5) were manufactured using the aluminum alloy powders (P1 to P5). Their respective compositions are shown in Table 4 below. The compositions of the additive manufacturing products B1, B4 to B5 have not been measured, and these compositions should approximately match the compositions of the powders (P1, P4 to P5). The aluminum alloy powders P1 and P5 contain Sc and Zr used in amounts outside the scope of the present invention, while the aluminum alloy powders P2 to P4 contain elements within the scope of the present invention. All of the additive manufacturing products B1 to B5 are "as-built" samples that do not undergo further heat treatment (step 3). The additive manufacturing products were manufactured under the following conditions. Specifically, an additive manufacturing apparatus EOS M290 (LPBF method) was used as the additive manufacturing method, and the additive manufacturing conditions were a preheating temperature of 25°C to 200°C, an energy density of 100 J / mm 3 ~200 J / mm 3 , and a layer thickness of approximately 0.03 mm. The energy density was set using the following formula: Energy density (J / mm 3 ) = Laser output (W) / (Scanning speed (mm / s) × Scanning pitch (mm) × Layer thickness (mm)).

[0090]

[0091]

[0092]

[0093]

[0094]

[0095] Table 4: Compositions of aluminum alloy powders and additive manufacturing products:Table 5: Evaluation results of powder characteristics:​​​From the results shown in Table 5 above, and in comparison, the aluminum alloy powders (P1~P5) have a volume-based median diameter (D 50 ) is approximately 28-39 μm, D 10 Approximately 14-21 μm, D 90 It was found that the particles have a particle size of approximately 52-64 μm. In addition, it was found that all aluminum alloy powders (P1-P5) had a sphericity of 71.5% or higher and an imperfect sphericity of 29% or lower.

[0096] The mechanical properties, presence or absence of cracks, and porosity of the obtained additively fabricated parts (B1-B5) were evaluated. The results are shown below.

[0097] Specifically, the mechanical properties were measured according to ASTMk E8 / E8M-13a.

[0098] The results of the mechanical property evaluation of additively manufactured parts B1 to B5 are shown in Table 6 below, and for comparison, the mechanical properties of conventional A6061 material are shown in Table 7. Furthermore, the results of the crack evaluation and porosity of additively manufactured parts B1 to B5 are shown in Table 8 below.

[0099] Table 6: Evaluation results of mechanical properties of additively manufactured parts (B1-B5):

[0100] [Table 6]

[0101] Table 7: Mechanical properties of conventional A6061 material (reference material):

[0102] [Table 7]

[0103] Table 8: Crack evaluation and porosity of additively manufactured products B1-B5

[0104] [Table 8]

[0105] From the results shown in Table 6 above, it can be seen that additively manufactured products B2 to B4 exhibit superior mechanical properties in terms of tensile strength, yield strength, and elongation. In contrast, additively manufactured product B1 has inferior mechanical properties, and cracks were observed in the manufactured product. This is because B1 uses a powder composition P1 that contains amounts of Sc / Zr outside the range of the present invention (Sc: 0.46 to 0.80 mass%, Zr: 0.15 to 0.4 mass%). Furthermore, as shown in additively manufactured product B5, when the Sc / Zr content is higher than the range of the present invention, although the tensile strength is high, the yield strength and elongation are lower compared to additively manufactured products B2 to B4 (including compositions within the range of the present invention).

[0106] Furthermore, a comparison with the mechanical properties of conventional A6061 material shown in Table 7 reveals that the mechanical properties of additively manufactured parts B2-B4 are even more improved compared to the conventional material. Additionally, as shown in Table 8, the porosity of additively manufactured parts B2-B5 is even lower than that of additively manufactured part B1. It is also shown that no cracks were observed in additively manufactured parts B2-B4 (see Figures 18-20).

[0107] The reason no cracks are observed is that ultrafine particles are formed at the boundary of the molten pool. These particles interfere with the epitaxial growth of long columnar particles within the alloy without additional modification, reducing crack susceptibility. Using aluminum alloy powder P2 as an example, we further evaluated the microstructure and assessed the effects of heat treatment.

[0108] By using aluminum alloy powder P2 as a raw material (composition containing elements within the scope of the present invention), the microstructure of the additively fabricated product in its as-form state (without further heat treatment) was further evaluated, as shown in Figures 22 and 23. The two examples show different ultrafine grain fractions, corresponding to relatively low energy density (Figure 22) and relatively high energy density (Figure 23), respectively. The ultrafine grain size is less than 1 μm.

[0109] The microhardness of the samples shown in Figures 22 and 23 is 84-103 HV. 0.1The tensile properties of the samples shown in Figures 22 and 23 are shown in Table 9.

[0110] Table 9: Tensile strength of as-printed samples (additive manufacturing):

[0111] [Table 9]

[0112] The contribution to strength improvement in the as-formed sample is mainly derived from grain boundaries. Precipitates provide one of the main elements for the strength of aluminum alloys. Therefore, controlling precipitates is important for controlling the properties, and this control is achieved through heat treatment control. There are two methods for programming the heat treatment of this alloy, including DA and STA as mentioned above.

[0113] (1) It depends on the addition of elements, namely precipitates consisting of Sc and Zr. The precipitate is Al3(Sc,Zr). To achieve this, it is necessary to apply a suitable temperature (250~450°C). The duration can vary from 5 minutes to 100 hours depending on the original microstructure and the required properties. This method is called direct aging (DA).

[0114] (2) It depends on the original elements, namely the precipitates made of Mg and Si. The precipitates are Mg x Si y Therefore, to achieve this, solution treatment is first necessary. Solution treatment is performed at a high temperature (460-550°C) for 5 minutes to 10 hours. After holding, the parts are water-quenched. After solution treatment, the parts are aged, which is done at a low temperature (140-220°C) for 30 minutes to 100 hours. This method is called solution aging (STA).

[0115] When DA was performed on the sample of Example E2, the DA was held at 400°C for 1 hour (referred to as Example E3). The TEM results in Figure 24 show coherent secondary Al3(Sc,Zr) as a strengthening phase in the sample. The sample of Example 2 was subjected to STA treatment, held at 550°C for 0.5 hours, then water quenched, and subsequently held at 175°C for 8 hours (referred to as Example E4). The TEM observation results in Figure 25 show that needle-shaped precipitates are nucleated in the sample. These needle-shaped precipitates are Mg x Si y That is the case.

[0116] The microhardness of the DA sample depends on temperature and holding time. The maximum microhardness can exceed 120HV0.1. The microhardness of the STA sample also depends on temperature and holding time. Example E4 shows a microhardness of ~110HV0.1.

[0117] Examples of tensile properties of heat-treated samples are shown in Table 10 below. In addition to Examples E3 and E4, the following examples are also included for comparison:

[0118] Example 5: A sample with the microstructure shown in Example E1 was directly aged at 400°C for 1 hour.

[0119] Example E6: A sample having the microstructure shown in Example E1 was solution-treated at 520°C for 0.5 hours, then quenched in water, and held at 175°C for 8 hours.

[0120] Table 10: Tensile properties of samples after heat treatment:

[0121] [Table 10]

[0122] By comparing the microstructure and tensile properties shown in Table 10 above, the strengthening mechanism of the heat-treated samples depends on the contributions of both grain boundary strengthening and precipitate strengthening. In the DA sample, coherent secondary Al3(Sc,Zr) precipitates are the main contributing factor. In the STA sample, coherent Al3(Sc,Zr) and needle-like precipitates are the main contributing factors.

[0123] Based on the above examples, when using the LPBF process to create additively manufactured parts (without further heat treatment), a bimodal particle size distribution can be obtained that includes ultrafine particles smaller than 1 μm and columnar particles larger than 1 μm, resulting in 84HV 0.1 The above minute hardness levels can be achieved. Furthermore, by incorporating specified amounts of aluminum, magnesium, copper, chromium, silicon, scandium, and zirconium into the aluminum alloy powder P2 used as a raw material for manufacturing additively fabricated products, the resulting product is crack-free, has a yield strength and tensile strength of 250 MPa or higher, and an elongation of 16% or higher.

[0124] In DA-treated samples, nano-sized Al3(Sc,Zr) precipitates were observed using a transmission electron microscope. These precipitates are the main contributors to the strengthening of this state, and the ultrafine grain size is maintained at 1 μm or less. Similarly, DA-treated samples exhibit yield strength and ultimate tensile strength of 300 MPa or higher, and elongation of 3% or higher. In STA-treated samples, nano-sized Al3(Sc,Zr) precipitates and needle-like precipitates were observed using a transmission electron microscope. These precipitates are the main contributors to the strengthening of this state, and the grain size is in the range of 100 nm to 200 μm. Similarly, STA-treated samples exhibit ultimate tensile strength of 330 MPa or higher, while simultaneously having a yield strength of 270 MPa or higher. [Industrial applicability]

[0125] The alloy powders (Al6xxx and Al7xxx) and additively manufactured products of the present invention can be used in a wide range of engineering applications, from the aerospace, automotive, and semiconductor industries to the marine and defense industries.

Claims

1. An aluminum-based composition, Aluminum, magnesium, copper, chromium, silicon, scandium, zirconium, Aluminum, magnesium, copper, chromium, scandium, and one or more other metals besides zirconium Includes, Based on the total amount of the aluminum-based composition, scandium is present in an amount of 0.46 mass% to 0.80 mass%, and zirconium is present in an amount of 0.15 mass% to 0.40 mass%. Aluminum-based composition.

2. Based on the total amount of the aluminum-based composition, scandium is present in an amount of 0.46 mass% to 0.72 mass%, and zirconium is present in an amount of 0.15 mass% to 0.36 mass%. The aluminum-based composition according to claim 1.

3. Based on the total amount of the aluminum-based composition, the magnesium is present in an amount of 0.8 mass% to 1.4 mass%. The aluminum-based composition according to claim 1.

4. Based on the total amount of the aluminum-based composition, the copper is present in an amount of 0.15 mass% to 0.4 mass%. The aluminum-based composition according to claim 1.

5. Based on the total amount of the aluminum-based composition, the chromium is present in an amount of 0.04 mass% to 0.45 mass%. The aluminum-based composition according to claim 1.

6. Based on the total amount of the aluminum-based composition, the silicon is present in an amount of 0.4 mass% to 1.0 mass%. The aluminum-based composition according to claim 1.

7. The aluminum-based composition further contains zinc present in an amount of less than 0.25 mass%, based on the total amount of the aluminum-based composition. The aluminum-based composition according to claim 1.

8. The one or more other metals mentioned above include iron, manganese, and / or titanium. The aluminum-based composition according to claim 1.

9. Based on the total amount of the aluminum-based composition, the iron is present in an amount of less than 0.2 mass%, and the manganese and titanium are present in amounts of less than 0.3 mass, respectively. The aluminum-based composition according to claim 8.

10. An aluminum-based composition, Aluminum, zinc, magnesium, copper, chromium, scandium, zirconium, Aluminum, zinc, magnesium, copper, chromium, scandium, and one or more other metals besides zirconium Includes, Based on the total amount of the aluminum-based composition, scandium is present in an amount of 0.35 mass% to 1.04 mass%, and zirconium is present in an amount of 0.15 mass% to 0.52 mass%. Aluminum-based composition.

11. Based on the total amount of the aluminum-based composition, the zinc is present in an amount of 5.5 mass% to 7.0 mass%. The aluminum-based composition according to claim 10.

12. Based on the total amount of the aluminum-based composition, the magnesium is present in an amount of 2.3 mass% to 3.2 mass%. The aluminum-based composition according to claim 10.

13. Based on the total amount of the aluminum-based composition, the copper is present in an amount of 1.2 mass% to 2.0 mass%. The aluminum-based composition according to claim 10.

14. Based on the total amount of the aforementioned aluminum-based composition, the chromium is present in an amount of 0.28 mass% or less. The aluminum-based composition according to claim 10.

15. The aluminum-based composition further contains silicon present in an amount of less than 0.2 mass%, based on the total amount of the aluminum-based composition. The aluminum-based composition according to claim 10.

16. The one or more other metals mentioned above include iron, manganese, titanium, nickel, lead, tin, and / or vanadium. The aluminum-based composition according to claim 10.

17. Based on the total amount of the aforementioned aluminum-based composition, The aforementioned iron is present in an amount of less than 0.2 mass%, The manganese and titanium are present in amounts of 0.1 mass% or less, The nickel and lead are present in amounts of 0.01 mass% or less, The tin and vanadium are present in amounts of less than 0.01 mass%, The aluminum-based composition according to claim 16.

18. Based on the total amount of the aforementioned aluminum-based composition, Oxygen present in amounts less than 0.03 mass%, Nitrogen present in amounts of less than 0.01 mass%, Hydrogen present in an amount of 0.001 mass% and This also includes, The aluminum-based composition according to claim 10.

19. Aluminum-based composition according to claims 1 to 18 including, Aluminum alloy powder.

20. Formed by using the aluminum-based compositions described in claims 1 to 18 Aluminum alloy additive manufacturing product.

21. The aluminum-based composition described in claim 1 is induced to melt and produce a molten aluminum alloy, The molten aluminum alloy is treated by a gas atomization method. including, A method for forming aluminum alloy powder.

22. The aforementioned gas atomization method is, (i) Pressure of 40-45 bar, (ii) Power of 20-30 kW, and / or (iii) Temperatures between 60°C and 100°C It will be held The method according to claim 21.

23. The aforementioned aluminum alloy powder does not contain any cracks. The method according to claim 21.

24. Using the aluminum alloy powder described in claim 19 as a raw material powder for additive manufacturing. including A method for manufacturing products using additive manufacturing.

25. The additive manufacturing method is a powder bed fusion method using an electron beam or laser, or a directed energy deposition method using an electron beam or laser. The method according to claim 24.

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