Metal powder for additive manufacturing, additive products using the same, and methods for manufacturing the same.

Abstract

This invention provides a metal powder suitable for manufacturing additive products that have a tensile strength of 400 MPa or more, a 0.2% yield strength of 250 MPa or more, and an elongation at break of 1.5% or more at room temperature. [Solution] An additive manufacturing metal powder is used, which contains 0.20% to 6% by mass of nickel as an alloying element to aluminum, and 0.20% to 10% by mass of at least one selected from the group consisting of manganese, chromium, copper, scandium, and zirconium, and the total content of nickel, manganese, chromium, and copper is 5% to 12% by mass, and the content of nickel relative to the total amount of alloying elements other than aluminum is 10% to 50% by weight.

Description

[Technical Field]

[0001] The present invention relates to aluminum alloy powder for producing additive products made of aluminum alloy having high relative density and excellent room-temperature strength. [Background technology]

[0002] Conventionally, Al-Si casting alloys, such as Al-10%Si-0.4%Mg (ISO-AlSi10Mg) alloy, have been mainly used as aluminum alloy materials for additive manufacturing (additive manufacturing). The additively manufactured products (formed bodies) exhibit an extremely fine cellular dendrite structure on the submicron order due to the effect of rapid solidification by irradiation with a laser, etc., and show excellent mechanical properties (strength and elongation at break) in the as-printed material.

[0003] Aluminum alloy powders for additive manufacturing (additive manufacturing) have been developed, including aluminum alloy powders containing silicon and magnesium (e.g., Patent Document 1), and aluminum alloy powders containing specific amounts of iron, manganese, chromium, nickel, and zirconium (e.g., Patent Document 2). Furthermore, the mechanical properties of fabricated objects using aluminum alloy powders containing silicon and magnesium have been investigated (Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] WO2017 / 203717 Brochure [Patent Document 2] WO2022 / 080319 Brochure [Non-patent literature]

[0005] [Non-Patent Document 1] Journal of the Laser Processing Society of Japan: Takahiro Kimura, Vol.25, No.3 (2018), 164-173 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] When manufacturing objects using the additive manufacturing method with aluminum alloy powder as described above, if the object is fabricated at a high temperature of 150°C or higher without preheating, the internal (residual) stresses of the additive product may not be properly removed, resulting in significant thermal deformation. Furthermore, if the fabricated additive product is used without heat treatment, risks such as deformation due to residual internal stress, deterioration of mechanical properties, reduction in fatigue strength, and reduction in corrosion resistance may occur. Therefore, in order to ensure the shape accuracy, proper mechanical properties, and reliability of the additive products, it is necessary to perform appropriate preheating and heat treatment.

[0007] However, the technology described in Patent Document 1 tends to decrease in strength with preheating and heat treatment, making it difficult to use in components requiring high strength. Furthermore, while the technology described in Patent Document 2 improves high-temperature strength and high-temperature Young's modulus by adding transition metal elements to aluminum, the strength at room temperature after heat treatment is only about 300 MPa, and excessive addition of transition metals leads to a decrease in elongation at break. For applications such as structural components in automobiles and aircraft, aluminum alloys with high strength and appropriate ductility at room temperature are required, specifically, a tensile strength of 400 MPa or more, a 0.2% yield strength of 250 MPa or more, and an elongation at break of 1.5% or more at room temperature. Therefore, it is difficult to obtain such performance with the technologies described in Patent Documents 1 and 2.

[0008] Therefore, the present invention aims to provide a metal powder suitable for manufacturing additive products having a tensile strength of 400 MPa or more, a 0.2% yield strength of 250 MPa or more, and an elongation at break of 1.5% or more at room temperature. [Means for solving the problem]

[0009] In response to the above problems, the inventors of the present invention considered various options and came up with the following configurations [1] to

[12] . [1] Additive manufacturing metal powder comprising aluminum, nickel as an alloying element, 0.20% by mass or more and 6% by mass or less, and at least one selected from the group consisting of manganese, chromium, copper, scandium, and zirconium, at 0.20% by mass or more and 10% by mass or less, wherein the total content of nickel, manganese, chromium, and copper is 5% by mass or more and 12% by mass or less, and the content of nickel relative to the total amount of alloying elements other than aluminum is 10% by weight or more and 50% by weight or less. [2] The additive metal powder according to [1], wherein the total content of scandium and zirconium is 0.2% by mass or more and 3% by mass or less. [3] The additive metal powder according to [1], further containing iron, wherein the iron content is less than 4.5% by mass. [4] The additive metal powder according to [1], further containing silicon, wherein the silicon content is less than 1% by mass.

[0010] A method for manufacturing an additive product, comprising: a first step of forming a powder layer containing an additive metal powder described in any of [5][1] to [4]; and a second step of forming a metal layer by solidifying the metal powder at predetermined positions in the powder layer, wherein the first and second steps are repeated sequentially, and the product is manufactured by stacking and joining multiple metal layers. [6] A method for producing an additive product according to [5], comprising the step of preheating the metal layer and the powder layer at a temperature of 50°C or more and 500°C or less in the first and second steps. [7] A method for producing an additive according to [5], further comprising a third step of heat-treating the additive after the second step. [8] The method for producing an additive according to [7], wherein in the third step, the additive is heat-treated at a temperature of 100°C to 650°C. [9] A method for producing an additive according to [6], further comprising a third step of heat-treating the additive after the second step.

[10] The method for producing an additive according to [9], wherein in the third step, the additive is heat-treated at a temperature of 100°C to 650°C.

[0011]

[11] An additive product containing aluminum, with nickel as an alloy element in a content of 0.20% by mass or more and 6% by mass or less, containing at least one selected from the group consisting of manganese, chromium, copper, scandium, and zirconium in a content of 0.20% by mass or more and 10% by mass or less, and having a total content of nickel, manganese, chromium, and copper of 5% by mass or more and 12% by mass or less, with the content of nickel relative to the total amount of alloy elements other than aluminum being 10% by weight or more and 50% by weight or less, and having a relative density of 95% or more and 100% or less.

[12] The additive product according to

[11] , wherein the total content of scandium and zirconium is 0.2% by mass or more and 3% by mass or less.

[13] The additive product according to

[11] or

[12] , further containing iron with an iron content of less than 4.5% by mass.

[14] The additive product according to

[11] or

[12] , further containing silicon with a silicon content of less than 1% by mass. [Advantages of the Invention]

[0012] As described above, as alloying elements added to aluminum for improving mechanical properties after preheating or heat treatment, nickel for structural composite strengthening, chromium for solid solution strengthening, manganese, copper, scandium, and zirconium for dispersion and precipitation strengthening by forming compounds with aluminum are added, thereby improving mechanical properties. That is, an aluminum alloy powder for additive manufacturing (layered manufacturing) can be provided to produce an additive product having a tensile strength of 400 MPa or more, a 0.2% proof stress of 250 MPa or more, and an elongation at break of 1.5% or more at room temperature. [Brief Description of the Drawings]

[0013] [Figure 1] (a) A process diagram for explaining the steps of a method for manufacturing an additive product according to an embodiment of the present invention. (b) A process diagram for explaining the steps of a method for manufacturing an additive product according to an embodiment of the present invention following (a). (c) A process diagram for explaining the steps of a method for manufacturing an additive product according to an embodiment of the present invention following (b). [Figure 2](a) A process diagram illustrating the steps of the manufacturing method for the additive product, following Figure 1(c). (b) A process diagram illustrating the steps of the manufacturing method for the additive product, following (a). (c) A process diagram illustrating the steps of the manufacturing method for the additive product, following (b). [Figure 3] Following Figure 2(c), this is a process diagram illustrating the steps of the manufacturing method for the additive product. [Figure 4] Plan view of a test specimen used in tensile testing. [Figure 5] (a) A photograph showing the shape of the manufactured appendix. (b) A photograph showing the shape of the cylindrical appendix used to produce the tensile test specimen. [Figure 6] (a) Optical microscope image of a vertical cross-section of the manufactured adduct (Example 1). (b) Optical microscope image of a vertical cross-section of the manufactured adduct (Example 2). (c) Optical microscope image of a vertical cross-section of the manufactured adduct (Example 3). (d) Optical microscope image of a vertical cross-section of the manufactured adduct (Example 4). [Figure 7] (a) Optical microscope image of a vertical cross-section of the manufactured adduct (Example 5). (b) Optical microscope image of a vertical cross-section of the manufactured adduct (Comparative Example 1). (c) Optical microscope image of a vertical cross-section of the manufactured adduct (Comparative Example 2). (d) Optical microscope image of a vertical cross-section of the manufactured adduct (Comparative Example 3). [Figure 8] (a) Optical microscope image of a vertical cross-section of the manufactured adduct (Comparative Example 4). (b) Optical microscope image of a vertical cross-section of the manufactured adduct (Comparative Example 5). [Figure 9] (b) A graph showing the change in Vickers hardness of an adduct product due to heat treatment (Example 1). (c) A graph showing the change in Vickers hardness of an adduct product due to heat treatment (Example 2). (d) A graph showing the change in Vickers hardness of an adduct product due to heat treatment (Example 3). [Figure 10] (a) Graph showing the change in Vickers hardness of the adduct by heat treatment (Example 4). (b) Graph showing the change in Vickers hardness of the adduct by heat treatment (Example 5). [Figure 11](a) Scanning electron microscope (SEM) backscattered electron image of a horizontal cross section of the manufactured adduct (Example 1). (b) Scanning electron microscope (SEM) backscattered electron image of a horizontal cross section of the manufactured adduct (Example 2). (c) Scanning electron microscope (SEM) backscattered electron image of a horizontal cross section of the manufactured adduct (Example 3). [Figure 12] (a) Scanning electron microscope (SEM) backscattered electron image of a horizontal cross section of the manufactured adduct (Example 4). (b) Scanning electron microscope (SEM) backscattered electron image of a horizontal cross section of the manufactured adduct (Example 5). [Modes for carrying out the invention]

[0014] The metal powder for additive manufacturing of the present invention contains 0.20% to 6% by mass of nickel as an alloying element in aluminum, and 0.20% to 10% by mass of at least one selected from the group consisting of manganese, chromium, copper, scandium, and zirconium, and the total content of nickel, manganese, chromium, and copper is 5% to 12% by mass, and the content of nickel relative to the total amount of alloying elements other than aluminum is 10% to 50% by weight. Embodiments of the present invention will be described below. The present invention relates to aluminum alloy powder for manufacturing additive products (hereinafter referred to as "additive manufacturing metal powder"), a method for manufacturing additive products using this additive manufacturing metal powder, and additive products. However, the following description is not intended to limit the scope of the invention of this disclosure.

[0015] <Metal powders for additive manufacturing> The additive manufacturing metal powder of the present invention corresponds to toner and ink in a two-dimensional printer. This additive manufacturing metal powder is an aluminum alloy powder mainly composed of aluminum (Al), containing nickel (Ni) as an alloying element, and containing at least one selected from manganese (Mn), chromium (Cr), copper (Cu), scandium (Sc), and zirconium (Zr). Furthermore, it may optionally contain iron (Fe), silicon (Si), etc., as alloying elements.

[0016] The nickel content of this additive manufacturing metal powder is preferably 0.2% by mass or more, more preferably 1% by mass or more. It is also preferably 6% by mass or less, more preferably 5% by mass or less, and even more preferably 4% by mass or less. When the content is within these ranges, the additive product made using the additive manufacturing metal powder can exhibit excellent mechanical properties such as high relative density, sufficient ductility, and sufficiently improved room temperature strength. If the content is higher than the above range, the ductility of the additive product made using the additive manufacturing metal powder may be significantly reduced. If the content is lower than the above range, the room temperature strength of the additive product made using the additive manufacturing metal powder may not be sufficiently improved.

[0017] The content of at least one element selected from manganese, chromium, copper, scandium, and zirconium is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. It is also preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 7% by mass or less, and particularly preferably 6% by mass or less. When the content is within these ranges, it is possible to exhibit excellent mechanical properties such as high relative density, sufficient ductility, and sufficiently improved room temperature strength. If the content is higher than the above range, the ductility of the additive product made using the additive metal powder may decrease significantly, and the melting point of the powder may increase, making it difficult to manufacture the additive metal powder. If the content is lower than the above range, the room temperature strength of the additive product made using the additive metal powder may not improve sufficiently.

[0018] The total content of nickel, manganese, chromium, and copper is preferably 5% by mass or more, more preferably 6% by mass or more, and even more preferably 7% by mass or more. Furthermore, 12% by mass or less is preferable, more preferably 11% by mass or less, even more preferably 10% by mass or less, and particularly preferable 9% by mass or less. When the total content is within these ranges, the adducted product exhibits excellent mechanical properties, such as high relative density, sufficient ductility, and significantly improved room-temperature strength. If the content is higher than the above range, the melting point of the alloy may increase, making the production of the adducted product difficult, and the ductility of the adducted product may decrease significantly. If the content is lower than the above range, the room-temperature strength of the adducted product may not improve sufficiently.

[0019] Furthermore, the nickel content relative to the total amount of alloying elements other than aluminum should preferably be 10% by weight or more, more preferably 12% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more. Also, 50% by weight or less is preferable, and 45% by weight or less is preferable. When the nickel content is within these ranges, the added product can exhibit excellent mechanical properties such as high relative density, sufficient ductility, and sufficiently improved room temperature strength. If the nickel content is higher than the above range, the ductility of the added product may decrease significantly. If the nickel content is lower than the above range, the room temperature strength of the added product may not improve sufficiently.

[0020] The total content of scandium and zirconium is preferably 0.2% by mass or more, more preferably 0.25% by mass or more. It is also preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1.5% by mass or less. When the total content is within these ranges, the adductor can exhibit excellent mechanical properties, such as high relative density, sufficient ductility, and significantly improved room-temperature strength. If the content is higher than the above range, the melting point of the powder increases, potentially making the production of the metal powder for adductor manufacturing difficult, and the ductility of the adductor decreases significantly. If the content is lower than the above range, the room-temperature strength of the adductor does not improve sufficiently.

[0021] This additive manufacturing metal powder may further contain iron. The iron content is preferably less than 4.5% by mass, more preferably less than 3% by mass, even more preferably less than 2% by mass, and particularly preferably less than 1% by mass. If the iron content is 4.5% by mass or more, the additive product made using the metal powder will become significantly brittle, and there is a risk of cracking such as interlaminar cracking.

[0022] Furthermore, this additive metal powder may also contain silicon. The silicon content is preferably less than 1% by mass, and more preferably less than 0.5% by mass. If the silicon content is 1% by mass or more, the ductility of the additive product made using the metal powder may decrease, and furthermore, cracks such as solidification cracks may occur.

[0023] The metal powder used for additive manufacturing may contain small amounts of impurity elements. These impurity elements may be elements that are inevitably mixed in during the production of aluminum alloy powder (unavoidable impurities), or they may be modifying elements that are intentionally added. The content of impurity elements is not particularly limited, but is preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.2% by mass or less.

[0024] Specific examples of the aforementioned impurity elements include magnesium (Mg), copper (Cu), zinc (Zn), lithium (Li), silicon (Si), iron (Fe), manganese (Mn), chromium (Cr), nickel (Ni), titanium (Ti), calcium (Ca), sodium (Na), strontium (Sr), yttrium (Y), niobium (Nb), molybdenum (Mo), tungsten (W), antimony (Sb), beryllium (Be), phosphorus (P), vanadium (V), tin (Sn), lead (Pb), bismuth (Bi), cobalt (Co), silver (Ag), gallium (Ga), scandium (Sc), cerium (Ce), boron (B), carbon (C), nitrogen (N), oxygen (O), and the like. The content of each element in the metal powder used for additive manufacturing can be measured by inductively coupled plasma emission spectroscopy (ICP emission spectroscopy) and inert gas fusion-infrared absorption spectroscopy, etc.

[0025] The particle size of the metal powder for additive manufacturing is not particularly limited, but the volume-based average particle size (median diameter d50) is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more. If the average particle size is less than 1 μm, the fluidity of the powder decreases, and there is a risk that a uniform powder layer cannot be formed in the manufacturing process of the additive product. On the other hand, the average particle size is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 100 μm or less, and particularly preferably 60 μm or less. If the average particle size exceeds 200 μm, the powder may get caught in the blade during additive manufacturing, making it difficult to spread evenly, and there is a risk that a normal powder layer cannot be formed.

[0026] The amount of oxygen contained in the metal powder for additive manufacturing is not particularly limited, but is preferably 0.001% by weight or more. It is also preferably 0.5% by weight or less, and more preferably 0.2% by weight or less. If the amount of oxygen exceeds this range, oxygen-related defects may occur in the additive product, potentially degrading its mechanical properties. If the amount of oxygen is below this range, there is a risk of the powder spontaneously igniting.

[0027] The moisture content in the metal powder used for additive manufacturing is not particularly limited, but is preferably 0.001% by weight or more. It is also preferably 0.5% by weight or less, and more preferably 0.2% by weight or less. If the moisture content exceeds this range, gas defects may occur in the additive product, potentially degrading its mechanical properties. It is industrially very difficult and impractical to reduce the moisture content below this range.

[0028] The aforementioned metal powder for additive manufacturing can be produced, for example, by gas atomization or water atomization, but it can also be produced by other methods such as the rotating electrode method, plasma atomization, centrifugal atomization, mechanical alloying, and chemical processes. As described above, by using the metal powder for additive manufacturing of the present invention, it is possible to manufacture additive products with high relative density and excellent mechanical properties at room temperature.

[0029] <Method of manufacturing additive products> Next, a method for producing an additive product using the aforementioned additive metal powder will be described. In this invention, powder bed fusion bonding, a type of additive manufacturing method, is used, but other additive manufacturing methods may also be used, for example, directed energy deposition (DMD) can be used. Furthermore, indirect additive manufacturing methods such as binder injection or fused deposition (FDM) may also be used. The additive product of the present invention comprises a first step of forming a powder layer containing the additive metal powder, and a second step of forming a metal layer by solidifying the additive metal powder at predetermined positions in the powder layer, wherein the first and second steps are repeated sequentially, and the product is manufactured by stacking and joining multiple metal layers.

[0030] <First and Second Processes> Specifically, as shown in Figure 1(a), the first step involves supplying additive manufacturing metal powder a onto a substrate 11 placed on a stage 14 in the chamber 10 by moving the squeegee 12 horizontally (in the direction of arrow A), thereby forming a powder layer P containing additive manufacturing metal powder a on the substrate 11. At this time, by adjusting the position of the vertically movable stage 14, a powder layer P of a desired thickness t can be formed.

[0031] Next, as shown in Figure 1(b), the laser scanning device 13 irradiates a laser beam onto an arbitrary area of ​​the surface of the metal powder layer P, heating the metal powder in the irradiated area. As a result, the metal powder in the laser-irradiated area melts or sintersects and solidifies, and then, as shown in Figure 1(c), a second step is performed in which the metal layer M is formed by irradiating the laser beam along a desired scanning path. Next, as shown in Figure 2(a), the first step is repeated in which the position of the stage 14 is moved downward by a predetermined thickness, and the squeegee 12 is moved horizontally (in the direction of arrow A) to supply the additive manufacturing metal powder a onto the metal layer M, thereby forming a powder layer P containing the additive manufacturing metal powder a on the substrate 11.

[0032] Next, as shown in Figure 2(b), the laser scanning device 13 irradiates a laser beam onto an arbitrary area of ​​the surface of the metal powder layer P, heating the metal powder in the irradiated area. As a result, the metal powder in the laser-irradiated area melts or sintersects and solidifies, and as shown in Figure 2(c), the metal layer M is formed by irradiating the laser beam along a desired scanning path, and the second step is repeated. At this time, when the powder layer P solidifies by melting or sintering to form the metal layer M, it is joined to the previously formed lower metal layer M, so the newly formed metal layer M becomes integrated with the lower metal layer M.

[0033] By sequentially repeating these first and second steps, an additive product M1 is manufactured in which multiple metal layers M are stacked and joined together, as shown in Figure 3. This additive manufacturing product, which is made by stacking and joining multiple layers, can be fabricated, for example, based on slice data converted from the three-dimensional shape data of the target additive manufacturing product using 3D CAD. The slice data is the shape data of each cross-section obtained by dividing the three-dimensional shape data of the additive manufacturing product into multiple layers, one above the other, with a predetermined stacking thickness t. By moving the base material 11 up and down using the stage 14 based on the predetermined stacking thickness t, and irradiating a predetermined area of ​​each of the multiple metal powder layers P stacked in the vertical direction with laser light based on the slice data, the metal powder is locally melted or sintered and solidified, thereby fabricating an additive manufacturing product with the desired shape.

[0034] Here, in the second step, the irradiation conditions when irradiating the metal powder layer P with laser light, that is, the output of the laser light, the scanning speed, the scanning interval, etc., can be appropriately adjusted within a range of, for example, 10000 W or less for the output, 30000 mm / s or less for the scanning speed, and 50 mm or less for the scanning interval, respectively. Further, the layer thickness t can be appropriately adjusted within a range of, for example, 10 mm or less. According to the research of the inventors, by irradiating the metal powder under the conditions optimized for each powder property such as the composition of the metal powder, the particle size distribution, and the powder shape, using the output P (W) of the laser light, the scanning speed V (mm / s), the scanning interval s (mm), and the layer thickness t (mm), an additive product having a high relative density can be obtained. E d = P / (V·s·t) The volume energy density E d (J / mm 3 ) calculated by the following formula

[0035] The volume energy density under the optimal laser irradiation conditions for manufacturing the additive product of the present invention to be dense (high relative density) is not particularly limited, but is preferably 30 J / mm 3 or more and 150 J / mm 3 or less, more preferably 40 J / mm 3 or more and 120 J / mm 3 or less, and even more preferably 40 J / mm 3 or more and 100 J / mm 3 or less. If it is lower than the above range, there is a risk of void defects due to unmelted parts inside the additive product. Also, if it is higher than the above range, there is a risk of spherical gas pores generated inside the additive product by entraining hydrogen derived from moisture adhering to the atmospheric gas or powder. Note that although laser light can be used as a heat source for melting and solidifying the metal powder, the means is not limited to laser light, and for example, an electron beam, plasma, or the like may be used.

[0036] In the manufacturing method of the present invention, the metal layer, the powder layer, and the adduct may be preheated in the first and second steps. The preheating temperature is preferably 50°C or higher, more preferably 100°C or higher, and even more preferably 150°C or higher. It is also preferably 500°C or lower, more preferably 400°C or lower, and even more preferably 250°C or lower. Preheating below 50°C does not sufficiently suppress cracking (delamination) and thermal deformation, and preheating at temperatures above 500°C causes the microstructure of the adduct to disappear and the mechanical properties to deteriorate. For preheating, an electric heater attached to the bottom of the build stage or base plate is usually used, but ceramic heaters or high-frequency heating may also be used. Alternatively, heating may be performed by scanning a heat source such as a laser beam or electron beam.

[0037] <3rd process> The manufacturing method of the present invention may further include a third step of heat-treating the adduct after the second step. In the third step of heat treatment, a temperature of 100°C or higher is preferred, and 150°C or higher is more preferred. Also, a temperature of 650°C or lower is preferred, 500°C or lower is more preferred, and 450°C or lower is even more preferred. Heat treatment below 100°C does not sufficiently improve strength, and heat treatment at temperatures above 650°C may cause the microstructure of the adduct to disappear, degrading its mechanical properties, or cause a change in the shape of the adduct due to partial melting. In the third step, a solution treatment (solid solution heat treatment) may be performed before the heat treatment. The furnace used for the heat treatment is usually an atmospheric furnace, but an atmospheric furnace may be used, for example, in an inert gas atmosphere such as nitrogen or argon, or in a reducing gas atmosphere such as hydrogen.

[0038] Furthermore, the time for the heat treatment is preferably 0.1 hours or more, more preferably 0.5 hours or more, and more preferably 1 hour or more. Also, it is preferably 1000 hours or less, more preferably 500 hours or less, more preferably 100 hours or less, and even more preferably 30 hours or less. If it is shorter than 0.1 hours, the strength of the additive may not improve sufficiently. On the other hand, if it is longer than 1000 hours, there is a risk that the strength of the additive will decrease due to over-aging.

[0039] <Additive Products> The additive product of the present invention is composed of an aluminum alloy of a specific composition that constitutes the metal powder for additive manufacturing described above. That is, this additive product mainly consists of aluminum, contains nickel, and contains at least one selected from the group consisting of manganese, chromium, copper, scandium, and zirconium. The nickel content of this adduct is preferably 0.2% by mass or more, more preferably 1% by mass or more. It is also preferably 6% by mass or less, more preferably 5% by mass or less, and even more preferably 4% by mass or less. When the content is within these ranges, the adduct has a high relative density, sufficient ductility, and can exhibit excellent mechanical properties such as sufficiently improved room temperature strength. If the content is higher than the above range, the ductility of the adduct may decrease significantly. If the content is lower than the above range, the room temperature strength of the adduct will not improve sufficiently.

[0040] The content of at least one element selected from manganese, chromium, copper, scandium, and zirconium is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. It is also preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 7% by mass or less, and particularly preferably 6% by mass or less. When the content is within these ranges, the adductor can exhibit excellent mechanical properties such as high relative density, sufficient ductility, and sufficiently improved room temperature strength. If the content is higher than the above range, the ductility of the adductor may be significantly reduced. If the content is lower than the above range, the room temperature strength of the adductor may not be sufficiently improved.

[0041] The total content of nickel, manganese, chromium, and copper is preferably 5% by mass or more, more preferably 6% by mass or more, and even more preferably 7% by mass or more. Furthermore, 12% by mass or less is preferable, more preferably 11% by mass or less, even more preferably 10% by mass or less, and particularly preferable 9% by mass or less. When the total content is within these ranges, the adducted product exhibits excellent mechanical properties, such as high relative density, sufficient ductility, and significantly improved room-temperature strength. If the content is higher than the above range, the melting point of the alloy increases, potentially making the production of the adducted product difficult, and the ductility of the adducted product decreases significantly. If the content is lower than the above range, the room-temperature strength of the adducted product does not improve sufficiently.

[0042] Furthermore, the nickel content relative to the total amount of alloying elements other than aluminum should preferably be 10% by weight or more, more preferably 12% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more. Also, 50% by weight or less is preferable, and 45% by weight or less is preferable. When the nickel content is within these ranges, the added product can exhibit excellent mechanical properties such as high relative density, sufficient ductility, and sufficiently improved room temperature strength. If the nickel content is higher than the above range, the ductility of the added product may decrease significantly. If the nickel content is lower than the above range, the room temperature strength of the added product may not improve sufficiently.

[0043] The total content of scandium and zirconium is preferably 0.2% by mass or more, more preferably 0.25% by mass or more. It is also preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1.5% by mass or less. When the total content is within these ranges, the adducted product exhibits excellent mechanical properties, such as high relative density, sufficient ductility, and significantly improved room-temperature strength. If the content is higher than the above range, the melting point of the alloy increases, making the production of the adducted product difficult, and the ductility of the adducted product decreases significantly. If the content is lower than the above range, the room-temperature strength of the adducted product does not improve sufficiently.

[0044] The iron content of the aforementioned adduct is preferably less than 4.5% by mass, more preferably 3% by mass or less, and even more preferably 2% by mass or less. If the iron content is 4.5% by mass or more, the adduct consisting of that composition will become significantly brittle, and there is a risk of cracking such as interlaminar cracking. Furthermore, the adduct may also contain silicon. The silicon content is preferably less than 1% by mass, and less than 0.5% by mass. If the content is 1% by mass or more, the ductility of the adduct made from that composition may decrease, and furthermore, cracks such as solidification cracks may occur.

[0045] The aforementioned additive product may contain small amounts of impurity elements. These impurity elements may be elements that are inevitably mixed in during the production of the aluminum alloy powder (unavoidable impurities), or they may be modifying elements that are intentionally added. The content of impurity elements is not limited, but is preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.2% by mass or less. Specific examples of the aforementioned impurity elements include magnesium (Mg), copper (Cu), zinc (Zn), lithium (Li), silicon (Si), iron (Fe), manganese (Mn), chromium (Cr), nickel (Ni), titanium (Ti), calcium (Ca), sodium (Na), strontium (Sr), yttrium (Y), niobium (Nb), molybdenum (Mo), tungsten (W), antimony (Sb), beryllium (Be), phosphorus (P), vanadium (V), tin (Sn), lead (Pb), bismuth (Bi), cobalt (Co), silver (Ag), gallium (Ga), scandium (Sc), cerium (Ce), boron (B), carbon (C), nitrogen (N), oxygen (O), and the like. The content of each element in the additive product can be measured using ICP emission spectroscopy and inert gas fusion-infrared absorption spectroscopy, etc., in the same manner as the method for measuring the content of each element in the metal powder used for additive manufacturing.

[0046] The adduct according to the present invention has a relative density of 95% or more and 100% or less. The relative density of the adduct is preferably 98% or more, more preferably 99% or more, and even more preferably 99.5% or more. If the relative density does not meet this range, the mechanical properties of the adduct will deteriorate significantly. This relative density is calculated by binarizing an optical microscope image (100x magnification) of an arbitrary vertical (parallel to the lamination direction) cross-section near the center of the additive, and taking the area ratio of the metal portion excluding the voids. A higher relative density is desirable for improving the mechanical strength, ductility, and thermal and electrical conductivity of the additive.

[0047] <Physical properties of additive products> The aforementioned additive has a room-temperature tensile strength of 400 MPa or more. Furthermore, the additive has a room-temperature 0.2% yield strength of 250 MPa or more. Due to these room-temperature tensile strengths and 0.2% yield strengths, the additive exhibits superior room-temperature strength compared to conventional technologies, making it applicable to a wide range of structural members. Furthermore, the added product has a room-temperature elongation at break of 1.5% or more. This room-temperature elongation allows the added product to exhibit superior ductility at room temperature compared to conventional technologies, making it applicable to a wide range of structural members. The room-temperature tensile strength, room-temperature 0.2% proof stress, and room-temperature elongation at fracture of the additive-type product are measured by a room-temperature tensile test. The tensile test specimen used in the tensile test has the shape shown in Figure 4. The strain rate in the tensile test is 0.3% / min up to the 0.2% proof stress, and 7.5% / min from the 0.2% proof stress until fracture.

[0048] The aforementioned additive has a room-temperature tensile strength of 400 MPa or higher, and more preferably 500 MPa or higher. By setting the strength to 400 MPa or higher, it is possible to prevent the additive from breaking when a load is applied and to exhibit good impact energy absorption characteristics. Furthermore, regarding the strength of the additive, the 0.2% yield strength at room temperature is preferably 250 MPa or higher in the as-formed state, more preferably 300 MPa or higher, and even more preferably 340 MPa or higher. After heat treatment, it is preferably 250 MPa or higher, more preferably 300 MPa or higher, even more preferably 340 MPa or higher, and particularly preferably 400 MPa or higher. By setting it to 250 MPa or higher, damage to the additive can be prevented when a load is applied.

[0049] Furthermore, the adductor should preferably have a room-temperature elongation of 1.5% or more, more preferably 3% or more, and even more preferably 5% or more. By setting it to 1.5% or more, sudden breakage of the adductor can be prevented when a load is applied, and good toughness and impact energy absorption characteristics can be achieved. The room-temperature elongation at break of the additive product is measured by a tensile test at room temperature. The tensile test specimen used in the tensile test has the shape shown in Figure 4. The strain rate in the tensile test is 0.3% / min up to the 0.2% proof stress, and 7.5% / min from the 0.2% proof stress until fracture.

[0050] Incidentally, when aluminum-transition metal alloys, such as the aforementioned additive manufacturing metal powder, are formed by conventional methods such as casting or powder metallurgy, the slow cooling rate results in the formation of coarse plate-like / needle-like compounds, and the mechanical properties of the material deteriorate significantly. In contrast, when additive manufacturing methods such as laser additive manufacturing, which involve irradiation with lasers or electron beams, are used, the rapid cooling and solidification caused by irradiation with lasers or electron beams results in an extremely fast cooling rate (10 3 ~10 6Non-patent document 1, etc., discloses that fabrication can be performed at K / s. Therefore, when such an additive manufacturing method and rapid solidification process are applied to aluminum-transition metal alloy powder, supersaturated solid solutions and non-equilibrium phases are generated by forced solid solution of transition metal elements, and heat treatment after fabrication makes it possible to form a structure in which high-temperature stable transition metal compounds are finely dispersed. Furthermore, some transition metal elements can be stably dissolved in aluminum up to high temperatures. As a result, the additively manufactured products of the present invention can exhibit excellent mechanical properties at room temperature due to dispersion and precipitation strengthening by transition metal compounds, structural composite strengthening and grain boundary strengthening, and solid solution strengthening of transition metal elements. [Examples]

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. First, the measurement method will be described.

[0052] (Measurement method) [Content of each element in metal powder for additive manufacturing] Measured by ICP emission spectroscopy.

[0053] [Volume energy density (E) under laser irradiation conditions] d )] Volume energy density of laser light in additive manufacturing (E d (J / mm 3 )) was calculated using the following formula. E d =P / (V·s·t) The laser output power P (W), scanning speed V (mm / s), scanning interval s (mm), and layer thickness t (mm) are as follows. Incidentally, for each metal powder used in additive manufacturing, the laser output P (W), scanning speed V (mm / s), and scanning interval s (mm) were varied to produce additive products, and the density of the produced additive products was measured using the Archimedes method. The density obtained by the Archimedes method can be measured in accordance with "JIS Z 2501: Sintered metal materials - Test methods for density, oil content and open porosity". Based on these results, the optimal laser irradiation conditions for each metal powder used in additive manufacturing were determined to obtain the highest density additive product. Furthermore, the E under the optimal conditions was determined. d The value was calculated using the above formula.

[0054] [Formability (presence or absence of cracks)] Optical microscope images (magnification 100x) of the vertical cross-section of the cylindrical (8 mm diameter, 15 mm height) additive products shown in Figure 5(a) obtained in each example and comparative example were taken. The laser irradiation conditions during the fabrication of the additive products were the optimal conditions determined for each metal powder used for additive manufacturing. Based on these images, the presence or absence of cracks in the additive products was determined.

[0055] [Relative density] The relative density of the adduct was calculated by binarizing an optical microscope image (magnification 100x) of an arbitrary vertical cross-section near the center of the cylindrical adduct shown in Figure 5(a) (diameter 8 mm, height 15 mm), and then determining the area ratio of the metal portion excluding the void.

[0056] [Tensile strength, 0.2% yield strength, elongation at break] Tensile strength, 0.2% proof stress, and elongation at break were all measured using a tensile testing apparatus of Grade 1 or higher, based on "JIS B 7721: Tensile testing machines and compression testing machines - Calibration and verification methods for force measuring systems". Tensile tests at room temperature were performed in accordance with "JIS Z 2241:2011: Tensile testing methods for metallic materials". The tensile test specimen used was prepared by turning the cylindrical appendix (12 mm in diameter, 80 mm in length), which was fabricated perpendicular to the lamination direction shown in Figure 5(b), into the shape shown in Figure 4. The dimensions of each part of the test specimen were as follows: total length L of the test specimen was 80 mm, length L1 of the main body was 30 mm ± 0.1 mm, diameter D1 of the main body was 6 mm ± 0.05 mm, radius of curvature R of the shoulder was 4.5 mm, length L2 of the gripping part was 15 mm, and diameter D of the gripping part 21 was 10 mm.

[0057] (1) Tensile strength The room-temperature tensile strength was measured using the following method after additive manufacturing, before heat treatment (as-formed) or after heat treatment and cooling to room temperature. The aforementioned tensile test specimen was pulled using a tensile testing device until it fractured, and the tensile load was measured at various points during the test. The strain rate in the tensile test was set to 0.3% / min up to the 0.2% yield strength, and then to 7.5% / min from the 0.2% yield strength until fracture. At this time, the jig of the tensile testing device was adjusted to grip the gripping part 21 of the test specimen and apply force in the axial direction of the test specimen 20. The tensile strength was then calculated by dividing the maximum tensile load by the cross-sectional area of ​​the main body 22 before the test (=π×D1×D1÷4).

[0058] (2)0.2% yield strength After additive manufacturing, before or after heat treatment, the 0.2% yield strength at room temperature was measured by the following method after cooling to room temperature. The aforementioned test specimen was pulled using a tensile testing apparatus until it fractured, and the tensile load was measured at any time during the test. Simultaneously, the displacement of the gauge length between the test points of the test specimen was measured at any time using an extensometer. In this case, the flange portion 24 of the main body of the test specimen for tensile testing was used as the gauge point, and the length L1 of the main body was used as the gauge length between the gauge points. The strain rate in the tensile test was set to 0.3% / min up to the 0.2% proof stress, and 7.5% / min from the 0.2% proof stress until fracture. The jig of the tensile testing apparatus was adjusted to grip the gripping portion of the test specimen and to apply force in the axial direction of the test specimen. Based on the above data of tensile load and gauge length displacement, a nominal stress-nominal strain curve was obtained. The nominal stress was calculated by dividing the tensile load by the cross-sectional area of ​​the main body before the test (=π×D1×D1÷4). The nominal strain was calculated as a percentage obtained by dividing the measured value of the gauge length displacement by the initial gauge length measured before the test. The 0.2% yield strength was calculated using the offset method described in "JIS Z 2241:2011:Tensile Test Methods for Metallic Materials".

[0059] (3) Elongation at break After additive manufacturing, before or after heat treatment, the room-temperature elongation at break was measured by the following method after cooling to room temperature. First, the flange portion of the main body of the tensile test specimen was used as the gauge point, and the length L1 of the main body was defined as the gauge point distance. The gauge point distance before the test was measured and defined as the initial gauge point distance. After performing the tensile test on the specimen, the fracture surfaces were butted together, taking care to ensure that the centerlines of both fractured fragments were aligned, and the gauge point distance after fracture was measured. The elongation at fracture was calculated as a percentage obtained by dividing the difference between this post-fracture gauge point distance and the initial gauge point distance by the initial gauge point distance. The strain rate in the tensile test was set to 0.3% / min up to the 0.2% proof stress, and to 7.5% / min from the 0.2% proof stress until fracture.

[0060] [Heat treatment conditions and Vickers hardness] The adducts produced in each example were heated in an atmospheric furnace to temperatures of 180°C to 400°C for 1 to 30 hours. No solution treatment was performed prior to the above heat treatment. After 1, 3, 5, 7, 10, 20, and 30 hours at each temperature, the samples were removed from the furnace and cooled to room temperature. The Vickers hardness (Hv0.2) was then measured using the following method with a load of 0.2 kgf. The Vickers hardness (Hv0.2) was measured according to "JIS Z 2244:2009: Vickers hardness test - Test method".

[0061] (Examples 1-5, Comparative Examples 1-5) Additive-formed products were fabricated using a laser-based powder bed fusion additive manufacturing method (laser additive manufacturing) with a laser as the heat source, using various additive-formed metal powders shown in Table 1. Each additive-formed metal powder was prepared by nitrogen gas atomization. The laser additive manufacturing system used was the EOSINT M280 manufactured by EOS GmbH in Germany, equipped with a ytterbium (Yb) fiber laser (laser wavelength: approximately 1070 nm) with a spot diameter of approximately 0.1 mm and an output of 400 W as the heat source. For each powder, the laser irradiation conditions during additive manufacturing were selected to obtain the conditions that yielded the highest density additive product (optimal conditions). For the optimal conditions for each powder, the volume energy density (E dThe following was calculated: In addition, the metal layer, powder layer, and additive products were preheated to 200°C before printing using an electric heater attached to the bottom of the printing stage of the laser additive manufacturing apparatus, and the temperature was controlled to maintain the same temperature while monitoring the temperature of a thermocouple attached inside the printing stage during printing. The properties of the manufactured adducts were measured using the method described above. The results are shown in Table 2.

[0062] Examples of the shapes of the manufactured add-ons are shown in Figures 5(a) and (b). Furthermore, optical microscope images of the vertical cross-section of the additive product with the shape shown in Figure 5(a) are shown in Figures 6(a)-(d) (Examples 1-4), Figures 7(a)-(d) (Example 5, Comparative Examples 1-3), and Figures 8(a) and (b) (Comparative Examples 4 and 5). Furthermore, the change in Vickers hardness of the added product due to heat treatment is shown in Figures 9(a)-(c) (Examples 1-3) and 10(a)-(b) (Examples 4 and 5). Note that the plot at the leftmost position (0 hours) in Figures 9 and 10 (white circle and "As-built") shows the hardness value of the added product in the as-built state (without heat treatment). Furthermore, scanning electron microscope (SEM) backscattered electron images of the horizontal cross-sections of the manufactured adducts (Examples 1-5) are shown in Figures 11(a)-(c) and 12(a)-(b).

[0063] [Table 1]

[0064] [Table 2]

[0065] (result) Figures 6-8 show optical microscope images of the vertical cross-sections of the manufactured additive products. In Examples 1-5 and Comparative Examples 1-3, no internal cracks were observed, indicating that dense molded bodies were obtained. On the other hand, in Comparative Examples 4 and 5, the high iron content led to material embrittlement, resulting in clear cracks perpendicular to the lamination direction. Figures 9-10 show the change in Vickers hardness of the additive products before and after heat treatment. In Examples 1, 2, 4, and 5, the hardness increased with heat treatment within a specific temperature range. In Example 3, the hardness was maintained despite heat treatment within a specific temperature range.

[0066] Table 2 shows the properties of the adducts before and after heat treatment. The adducts in each example are all high-density materials with a relative density of 99.5% or higher, exhibiting excellent room-temperature tensile strength, room-temperature 0.2% yield strength, and room-temperature elongation at break. On the other hand, Comparative Example 1 is a high-density material with a relative density of 99.5% or higher, but its room-temperature tensile strength and room-temperature 0.2% yield strength before and after heat treatment are low, which is undesirable. Comparative Examples 2 and 3 are also high-density materials with a relative density of 99.5% or higher, exhibiting excellent room-temperature tensile strength and room-temperature 0.2% yield strength, but their room-temperature elongation at break is low, which is undesirable. Furthermore, Comparative Examples 4 and 5 exhibit cracks, clearly indicating insufficient strength. As described above, the metal powder of the present invention has a relative density of 99.5% or more and has been shown to be an additive manufacturing metal powder capable of producing additive products having a tensile strength of 400 MPa or more, a 0.2% yield strength of 250 MPa or more, and an elongation at break of 1.5% or more at room temperature.

[0067] Figures 11-12 show scanning electron microscope (SEM) backscattered electron images of vertical cross-sections of the additive products for each example. In Example 1, a cellular dendritic structure is observed, with nickel and manganese concentrated at the cell boundaries. In Example 2, a cellular dendritic structure is observed similarly to Example 1, with nickel mainly concentrated at the cell boundaries. On the other hand, chromium is presumed to be supersaturated and dissolved in the matrix. In Example 3, a cellular dendritic structure is observed similarly to Examples 1 and 2, with nickel and copper mainly concentrated at the cell boundaries. In Example 4, a cellular dendritic structure is observed in the matrix, with granular phase crystallized / precipitation around the meltpool boundary. The granular phase is mainly concentrated with chromium and nickel. In Example 5, a cellular dendritic structure is observed in the matrix, and a granular phase is observed around the meltpool boundary, with chromium, nickel, and manganese mainly concentrated in the granular phase. Based on the above microstructural observations, it is presumed that the additive products prepared using the metal powder for additive manufacturing of the present invention exhibited excellent mechanical properties due to dispersion / precipitation strengthening by manganese, copper, scandium, zirconium-based compounds, solid solution strengthening mainly by chromium, and structural composite strengthening by a cellular dendrite structure mainly enriched with nickel. [Explanation of Symbols]

[0068] 10 Chambers 11 Base material 12 squeegee 13. Laser scanning device 14 stages 20 test specimens 21 Gripping part 22 Main body 23 Shoulder 24 Brim a. Metal powder for additive manufacturing t thickness M Metal layer M1 Additive Products P powder layer L Total length of the test specimen L1 Length of the main body (distance between gauge points) L2 Length of the gripping part D. Diameter of the gripping part D1 Diameter of the main body R: Radius of curvature of the shoulder

Claims

1. Aluminum contains nickel as an alloying element, with an amount of 0.20% to 6% by mass. It contains at least one element selected from the group consisting of manganese, chromium, copper, scandium, and zirconium in an amount of 0.20% by mass or more and 10% by mass or less, The total content of the aforementioned nickel, manganese, chromium, and copper is 5% by mass or more and 12% by mass or less. A metal powder for additive manufacturing, wherein the nickel content relative to the total amount of alloying elements other than aluminum is 10% by weight or more and 50% by weight or less.

2. The additive metal powder according to claim 1, wherein the total content of scandium and zirconium is 0.2% by mass or more and 3% by mass or less.

3. The additive metal powder according to claim 1, further containing iron, wherein the iron content is less than 4.5% by mass.

4. The additive metal powder according to claim 1, further containing silicon, wherein the silicon content is less than 1% by mass.

5. The first step is to form a powder layer containing the additive manufacturing metal powder described in any one of claims 1 to 4, and the second step is to form a metal layer by solidifying the metal powder at predetermined positions in the powder layer, A method for manufacturing an additive product, wherein the first and second steps are repeated sequentially, and multiple metal layers are stacked and joined together to produce the additive product.

6. A method for producing an additive product according to claim 5, comprising the step of preheating the metal layer and the powder layer at a temperature of 50°C or more and 500°C or less in the first and second steps.

7. A method for producing an additive product according to claim 5, further comprising a third step of heat-treating the additive product after the second step.

8. The method for manufacturing an additive according to claim 7, wherein in the third step, the additive is heat-treated at a temperature of 100°C to 650°C.

9. A method for producing an additive product according to claim 6, further comprising a third step of heat-treating the additive product after the second step.

10. The method for manufacturing an additive according to claim 9, wherein in the third step, the additive is heat-treated at a temperature of 100°C to 650°C.

11. Aluminum contains nickel as an alloying element, with an amount of 0.20% to 6% by mass. It contains at least one element selected from the group consisting of manganese, chromium, copper, scandium, and zirconium in an amount of 0.20% by mass or more and 10% by mass or less, The total content of the aforementioned nickel, manganese, chromium, and copper is 5% by mass or more and 12% by mass or less. The nickel content relative to the total amount of alloying elements other than aluminum is 10% by weight or more and 50% by weight or less. Additives having a relative density of 95% or more and 100% or less.

12. The additive product according to claim 11, wherein the total content of scandium and zirconium is 0.2% by mass or more and 3% by mass or less.

13. The additive product according to claim 11 or 12, further containing iron, wherein the iron content is less than 4.5% by mass.

14. The additive product according to claim 11 or 12, further containing silicon, wherein the silicon content is less than 1% by mass.

Images