EP4126422A1

EP4126422A1 - High-strength aluminum alloys for structural applications, which are processable by additive manufacturing

Info

Publication number: EP4126422A1
Application number: EP21716322.9A
Authority: EP
Inventors: Michael HÄRTEL
Original assignee: Am Metals GmbH
Current assignee: Am Metals GmbH
Priority date: 2020-03-30
Filing date: 2021-03-30
Publication date: 2023-02-08
Also published as: US20230135943A1; DE102020108781A1; JP2023525209A; WO2021198231A1; CN115427173A

Abstract

The present invention relates to pulverulent aluminum alloys having Cu, Zn or Si/Mg as most relevant alloy elements, the alloy further having a content of 1 to 15 wt.% of metals selected from the group M1 comprising Mo, Nb, Zr, Fe, Ti, Ta, V, and lanthanoids. Such aluminum alloys can be used in additive manufacturing methods, such as selective laser melting for producing high-strength three-dimensional objects which are free from hot cracks. The present invention further relates to methods and devices for producing three-dimensional objects from such aluminum alloys, to methods for producing such pulverulent aluminum alloys, to three-dimensional objects which are also produced by such pulverulent aluminum alloys, and to specific aluminum alloys.

Description

High-strength aluminum alloys that can be processed using additive manufacturing for

Structural applications

description

The invention relates to special powdery aluminum alloys with Cu, Zn or Si / Mg as the most relevant alloy element, which have a content of 1 to 15% by weight of metals selected from the group Ml comprising Mo, Nb, Zr, Fe,

Ti, Ta, V, and lanthanoids. The invention also relates to methods for making such aluminum alloys, methods and devices for the additive manufacturing of three-dimensional objects, as well as three-dimensional objects and special aluminum alloys produced according to this method.

State of the art

Light metal components are the subject of intensive research in the production of vehicles, in particular automobiles, aimed at continuously improving the performance and fuel efficiency of vehicles. Many light metal components for automotive applications today are made of aluminum and / or magnesium alloys. Such light metals can form load-bearing components that must be strong and stiff and have good strength and ductility (e.g. elongation). Flea firming Speed and elasticity are particularly important for safety requirements and robustness in vehicles, such as motor vehicles. While conventional steel and titanium alloys provide high temperature resistance, these alloys are each either heavy or comparatively expensive.

A cost-effective alternative to light metal alloys for forming structural components in vehicles are alloys based on aluminum.

Such alloys can conventionally be processed into the desired components by bulk formation processes such as extrusion, rolling, forging, stamping, or casting techniques such as die casting, sand casting, investment casting (investment casting), chill casting and the like.

From the prior art, high-strength aluminum alloys with sufficient plastic expansion to absorb energy are known, mainly from the field of wrought alloys. Materials from the aluminum 2000, 6000 and 7000 series are particularly suitable. These materials are characterized by their comparatively soft, ductile aggregate state, which enables them to be shaped. With the help of the energy introduced by massive forging and subsequent heat treatment, the alloys are converted into the high-strength and fully hardened state.

In recent years "rapid prototyping" or "rapid tooling" has also gained in importance in metal processing. These processes are also known as selective laser sintering and selective laser melting. A thin layer of a material in powder form is applied repeatedly and the material is selectively solidified in each layer in the areas in which the later product is located by exposure to a laser beam by first melting the material at predetermined positions and then solidifying it . In this way, a complete three-dimensional body can be built up successively.

A method for producing three-dimensional objects by selective laser sintering or selective laser melting and a device for implementing this method is disclosed in EP 1 762 122 A1, for example.

For processing by means of selective laser sintering or laser melting, an alloy is required whose precipitation mechanism works without prior cold forming. Corresponding alloys are made in particular known in the area of the 2000 alloys (ie aluminum-copper alloys). With these, however, the relatively large melting interval poses a problem, since hot cracks can occur in the structures as a result of the rapid solidification by low-melting eutectics, which do not withstand the shrinkage stresses unaffected when the structures solidify. When processing by means of selective laser sintering, only micro-cracked structures are generally obtained, so that conventional, high-strength wrought aluminum alloys have not yet been processable by means of additive manufacturing.

Other available aluminum alloys that are already established for processing using additive manufacturing techniques (such as those from the AlSi alloy family) do not have the desirable combination of properties of high yield strength and elongation at break, or are disadvantageous due to the very cost-intensive and rare alloying elements.

An example of an aluminum alloy with rare alloying elements is described in e.g. EP 3 181 711 A1, in which the aluminum is alloyed with relatively large amounts of Sc (0.6 to 3% by weight). In the alloys produced in this way, intermetallic Al-Sc phases have a strong increase in strength, so that yield strengths of> 400 MPa are achieved. In addition to the relatively cost-intensive metal Sc, which is required for the alloy, it is, however, disadvantageous that the alloys described in EP 3 181 711 Al are not suitable for operating temperatures of> 180 ° C., since the AlMg matrix is used for degreasing and creeping tends.

Another approach for alloys for use in additive manufacturing are AI-MMC (MMC = Matrix Metal Composite) concepts, which have mechanical properties comparable to AlMgSc alloys at room temperature. The problem with these materials, however, is that they show a significant drop in strength at temperatures above 200 ° C. Another problem with the AI-MMC concepts is that the material consists of a powder mixture of three components, which makes it difficult to transport, store and reuse, as a change in the mixing ratio due to physical processes cannot be ruled out. Another disadvantage is the negative recycling behavior of the MMC metal-ceramic composite materials and the fact that the mechanical reworking of AI-MMC is more difficult and associated with higher costs. Based on the prior art described above, there is a need for an aluminum alloy that is as inexpensive as possible, which is thermally stable and has high-strength properties, and which melts into three-dimensional objects with high strength and strength with the help of additive manufacturing techniques such as selective laser sintering and selective laser Rigidity th and favorable corrosion properties can be processed. Rare earth metals such as scandium, which are scarce on the market, should be avoided as far as possible in order to guarantee a high level of delivery security. There is still a need for an additive processing method for producing three-dimensional objects and for high-strength three-dimensional objects produced by these methods.

Description of the invention

This object is achieved by a powdery aluminum alloy as specified by claim 1, by a method for producing a three-dimensional object according to claim 9, by a method for producing the powdery aluminum alloy according to claim 8, by a three-dimensional object that is below Use of a powdery aluminum alloy as specified in claim 1, according to claim 11, by an apparatus for performing a method for manufacturing a three-dimensional object according to claim 14, and by an aluminum alloy as specified in claim 15. Preferred embodiments of the invention are given in the dependent claims.

The powdery aluminum alloy according to the invention is a powder for use in the manufacture of three-dimensional objects by means of additive manufacturing techniques. The powdery aluminum alloy according to the invention contains Cu, Zn or Si / Mg as the most relevant alloy element and also has a content of 1 to 15% by weight of metals selected from the group Ml comprising Mo, Nb, Zr, Fe, Ti, Ta, V , and lanthanides on. This aluminum alloy expediently contains no relevant proportions of Cr or Li (ie in particular less than 0.3% by weight, preferably less than 0.15% by weight and even more preferably less than 0.1% by weight total proportion of Cr and / or Li, and mostly preferably no proportions exceeding unavoidable impurities and Cr and / or Li). If the aluminum alloy contains Cr and / or Li, it must be ensured that the total proportion of metals in group Ml is added. Borrowed Cr and Li in the specified range of 1 to 15 wt.%, or in corresponding more preferred ranges, should be.

The term "aluminum alloy" is to be understood in the context of this description in such a way that the alloy contains aluminum as the most important metal element and its proportion in the aluminum alloy is more than 60% by weight, preferably more than 70% by weight and even more preferably more than 80% by weight. The statement "Cu, Zn or Si / Mg as the most relevant alloying element" should be interpreted in such a way that the proportion of Cu, Zn or Si / Mg is greater than the respective proportion of all other elements (with the exception of of aluminum) in the alloy, where Si / Mg denotes the total content of Si and Mg in the alloy (in this case the sum of the proportions of Si and Mg is greater than the respective proportion of all other elements (with the exception of aluminum) in the alloy). The “most relevant alloy element” relates to the aluminum alloy as such, ie without taking into account the additional metals from group Ml contained in the composition according to the invention, but it is preferred if the proportion of Cu or Zn is greater than the respective proportion of all other elements (with the exception of aluminum) in the alloy including the metals of group Ml.

The person skilled in the art is aware in this context that AICu alloys (ie alloys in which Cu is contained as the most relevant alloying element) also as aluminum alloys of the 2000 group, AIZn alloys (ie alloys in which Zn is contained as the most relevant alloying element) as well as aluminum alloys of the 7000 group and AISi / Mg alloys (ie alloys in which "Si / Mg" is contained as the most relevant alloy element) are also referred to as aluminum alloys of the 6000 group (in each case according to the International Alloy Designation System). For an overview For aluminum alloys falling under this category, reference can be made, for example, to https://en.wikipedia.org/wiki/Aluminium alloy # Allov designations.

The addition of metals from group Ml enables the production of essentially or even completely crack-free three-dimensional bodies by means of additive manufacturing techniques such as selective laser sintering or selective laser melting, although relatively large amounts of transition metals are added. This is surprising because with conventional aluminum Processing technologies is usually not possible to increase the alloy content of these transition metals over a defined limit (for example in the range from 0.1 to 0.3 wt .-%), since such an increase leads to a strongly decreasing ductility and thus not to a more given processability leads, which only allows the production of very coarse structural components. In the production of three-dimensional bodies and objects using additive manufacturing techniques described here, this problem is circumvented because the shaping does not require above-average ductility of the material, so that very fine and nano-scale structures can also be produced due to the process.

A preferred proportion for metals from group Ml can be a proportion of at least 1.3% by weight, preferably 2.0% by weight up to 8.0% by weight, and more preferably 2.5% by weight. -% up to 5.0% by weight can be specified. As an alternative or in addition to this, the metal or metals selected from group Ml does not consist in substantial proportions of lanthanides, the procurement of which can be costly, the proportion of lanthanides, based on the total amount of metals from group Ml, preferably being less than 10 wt .-%, more preferably less than 5% by weight, and even more preferably less than 1% by weight. Preferred metals from group Ml are easily obtainable and inexpensive metals such as Zr, Fe, and Ti, where Zr and / or Ti can be specified as particularly suitable. For Zr, a proportion of 0.25 to 2% by weight and in particular 0.5 to 1.9% by weight can be specified as being particularly suitable. Analogously, a proportion of 0.25 to 2% by weight and in particular 0.5 to 1.9% by weight can be specified as particularly suitable for Ti. It is particularly preferred if the aluminum alloy contains Zr and Ti as metals of group Ml and contains these in a proportion of 0.25 to 2% by weight and in particular 0.5 to 1.9% by weight in the aluminum alloy are.

The aluminum alloy according to the invention preferably does not contain any relevant proportions of Sc or Y, since these metals are associated with severe cost disadvantages. Preferred aluminum alloys according to the invention therefore contain a maximum of up to 1.5% by weight of Sc and / or Y, preferably a maximum of up to 1% by weight, even more preferably a maximum of 0.5% by weight and even more preferably none Amounts of Sc and Y in excess of the usual impurities. A powdery aluminum alloy particularly suitable in the context of this description is an aluminum alloy with a content of 4 to 6% by weight Cu, 0.1 to 1.5% by weight Mg and 0.1 to 1% by weight Ag. For this alloy, it is also preferred if, taking these elements and the elements from group Ml into account, the 98% by weight missing portion of the alloy, preferably the 99% by weight missing portion of the alloy on aluminum, falls away. In this case, the 100% by weight missing portion of the alloy is usually provided by other metals and / or non-metals such as oxygen, which however no longer have any significant influence on the mechanical properties of the alloy.

In a particularly preferred embodiment, the above-described aluminum alloy according to the invention has a content of at least 4.5% by weight and / or at most 5.8% by weight, preferably at least 4.8% by weight and / or at most 5.5% by weight % Cu, at least 0.2% by weight and / or at most 1.5% by weight, preferably at least 0.3% by weight and / or at most 1.2% by weight Mg, and at least 0 .05% by weight and / or at most 0.6% by weight, preferably at least 0.2% by weight and / or at most 0.4% by weight of Ag. As an alternative or in addition to this, the above-described aluminum alloy according to the invention preferably contains up to 0.2% by weight, in particular 0.05 to 0.15% by weight, of oxygen, up to 0.6% by weight, and in particular 0.2 up to 0.55% by weight of manganese and up to 0.3% by weight, preferably 0.05 to 0.15% by weight, silicon.

In a further particularly preferred embodiment, the above-described aluminum alloy according to the invention has a content of at least 0.2% by weight and / or at most 1.3% by weight, preferably at least 0.3% by weight and / or at most 1, 0% by weight Si, at least 0.4% by weight and / or at most 2.2% by weight, preferably at least 0.6% by weight and / or at most 1.8% by weight Mg, and at least 0.3% by weight and / or at most 1.3% by weight, preferably at least 0.4% by weight and / or at most 1.0% by weight of Mn. It is preferred for this aluminum alloy if it has a total content of Si and Mg in the range from 0.9 to 2.8% by weight and in particular in the range from 1.2 to 2.5% by weight.

For the aluminum alloys described above, it has been found that in products manufactured therefrom by additive manufacturing, desired mechanical parameters can be set by heat treatment. Due to the If the alloying elements are selected, the electrochemical rest potential of the matrix can also be shifted in the direction of more noble values compared to the precipitates, in order to achieve higher corrosion resistance and a significantly reduced susceptibility of the alloys to stress cracks.

With regard to the particle size, the powdery aluminum alloys according to the invention are not subject to any significant restrictions, the particle size should be in an order of magnitude that is suitable for an additive method for producing three-dimensional objects. A mean particle size d50 in the range from 0.1 to 500 μm, preferably at least 1 and / or at most 200 μm, and particularly preferably at least 10 and / or at most 80 μm, can be specified as a suitable particle size. A mean particle size d50 in the range from 10 to 80 μm is very particularly preferred.

As indicated further below, the powdery aluminum alloy according to the invention can also be present as a wire, e.g. for certain processing operations, so that a corresponding wire-like aluminum alloy is also the subject matter of the invention. d50 denotes the size at which the amount of particles by weight that have a diameter smaller than the specified size is 50% of the mass of a sample. Conventionally, as well as in the context of the invention described here, the particle size distribution is determined by laser scattering or laser diffraction, e.g. in accordance with ISO 13320: 2009 two points of the particle) or a sieve diameter or a volume-related equivalent spherical diameter.

As mentioned above, by including elements from group Ml, the tendency of the material to form stress cracks can be considerably reduced; in the ideal case, stress cracks are completely avoided. For this purpose, it is not necessary to include ceramic materials that have been described for similar purposes. Accordingly, the pulverulent aluminum alloy according to the invention contains as little as possible any added ceramic compounds, such as metal borides, nitrides and carbides in particular. Of the The proportion of such materials in the aluminum alloy is appropriately limited to less than 0.2% by weight, in particular less than 0.1% by weight and more preferably less than 0.05% by weight. Even nanoparticulate metals or metal hydrides (e.g. Zr, Hf or ZrH2, with particle sizes up to 5 μm), which have been described elsewhere in the prior art to avoid stress cracks, are not required for this purpose in the pulverulent aluminum alloys according to the invention, so that their proportion should be within the limits specified for metal borides, nitrides and carbides or ceramic additives. It is particularly advantageous if no corresponding materials are added to the pulverulent aluminum alloy according to the invention for or during its processing.

The powdery aluminum alloys according to the invention can be produced by any method that is known to the person skilled in the art for producing powdery alloys. A particularly useful method includes, for example, atomization of the liquid aluminum alloy or mechanical alloying. Accordingly, in a further aspect, the present invention relates to a method for producing a powdery aluminum alloy, which includes a step of atomizing the liquid alloy at a temperature of> 850 ° C, preferably> 950 ° C and more preferably> 1050 ° C. Temperatures of more than 1200 ° C are not required for the atomization and are less expedient due to the higher energy requirements. A range from> 850 to 1200 ° C. and preferably> 950 to 1150 ° C. can therefore be specified as a particularly favorable temperature range for the atomization. Sufficient overheating of the melt or process management must ensure that the above-mentioned temperatures are also constant at the nozzle in order to prevent undesired primary precipitations. A production of the pulverulent aluminum alloys by means of atomization has the advantage that the additive metals of group Ml are dissolved in the aluminum alloy or are present as metastable phases. During subsequent processing by means of laser sintering or laser melting, these phases are dissolved so that the metals can have a grain-refining effect.

Alternatively, the powdery aluminum alloy according to the invention can also be produced by mechanical alloying. Metal powders of the individual components of the later alloy (or premixes thereof) are mechanically treated intensively and homogenized down to the atomic level. For one Modification of the particles, following mechanical alloying, it is possible, please include to rework the particles obtained in order, for example, to change the morphology, particle size or particle size distribution or to carry out a surface treatment. The post-processing can include one or more steps selected from chemical modification of the particles and / or the particle surface, sieving, breaking, round grinding, plasma spherodizing (ie processing into round particles) and additives. In particular, modifications of the particle morphology or grain size distribution are expedient, since small plates or flakes are usually obtained in mechanical alloying. This form is generally problematic in a later additive processing method.

The present invention also relates to a powdery aluminum alloy which, according to the method described, is produced by atomizing the liquid alloy at a temperature of preferably> 850.degree. C. and more preferably>

1050 ° C, or by mechanical alloying with optional post-processing, reference is also made to the above explanations for preferred embodiments of atomization, mechanical alloying and optional post-processing.

Furthermore, a powdery aluminum alloy for use in the production of three-dimensional objects with the aid of additive manufacturing techniques is disclosed which, in addition to aluminum, contains Cu, Zn or Si / Mg as the most relevant alloy element and also a content of 1 to 15% by weight Metals selected from the group Ml comprising Mo, Nb, Cr, Zr,

Fe, Ti, Ta, V, lanthanoids and Li. The preferred embodiments disclosed above for the aluminum alloy according to the invention apply analogously as preferred for this pulverulent aluminum alloy.

Another aspect of the present invention relates to a method for manufacturing a three-dimensional object by means of an additive manufacturing method (ie a method in which an object is built up layer by layer). The object is preferably produced by applying a build-up material as a layer on top of a layer and selectively solidifying the build-up material, in particular by supplying radiant energy, at locations in each layer that are assigned to the cross-section of the object in this layer, preferably by having the locations with at least one Effective area, in particular a radiation exposure effective area of an energy beam, can be scanned, or in that the building material is introduced into the radiation effective area and melted and applied to a substrate. In the context of the invention described here, the construction material comprises a powdered aluminum alloy as indicated above, but can alternatively also comprise a corresponding wire-shaped aluminum alloy. The construction material preferably consists of this powdery or wire-like aluminum alloy.

The three-dimensional object can be an object made of one material (i.e. the aluminum alloy) or an object made of different materials. If the three-dimensional object is an object made of different materials, this object can be produced, for example, by applying the aluminum alloy according to the invention, for example, to a base body of the other material.

In the context of this process, it can be useful if the powdery aluminum alloy is preheated before the selective solidification, with preheating to a temperature of at least 110 ° C being preferred and preheating to a temperature of at least 120 ° C being more preferred Preheating to a temperature of at least 130 ° C as even more preferred, preheating to a temperature of at least 150 ° C as even more preferred, preheating to a temperature of at least 165 ° C as even more preferred and preheating to a Temperature of at least 190 ° C can be specified as even more preferred. On the other hand, preheating to very high temperatures places considerable demands on the device for producing the three-dimensional objects, i.e. at least on the container in which the three-dimensional object is formed, so that a maximum temperature of 400 ° C at most is a reasonable maximum temperature for preheating can be specified. The maximum temperature for preheating is preferably at most 350.degree. C. and more preferably at most 300.degree. The temperatures specified for preheating each designate the temperature to which the building platform form, to which the powdery aluminum alloy is applied, and the powder bed formed by the powdery aluminum alloy is heated.

The application or application layer on layer is expediently carried out in a layer thickness suitable for processing by means of additive manufacturing, for example with a layer thickness in the range from 20 to 60 μm, preferably with a thickness of at least 25 and / or at most 50 μm and more preferably with a thickness of at least 30 and / or at most 40 μm.

As indicated above, the method according to the invention can also be designed in such a way that the building material is introduced into the radiation exposure area of an energy source, for example a laser, and melted and applied to a substrate. In such a method, which is also referred to as a laser coating method (laser cladding) in the mode of powder deposition welding, a powder is sprayed punctiformly onto a substrate via one or more nozzles, and at the same time a laser is aligned with the application point of the laser. The substrate is melted by the radiation energy and the alloy powder applied is melted so that the alloy applied can bond with the melted substrate. In this way, a layer of the particulate material is applied to the workpiece and bonded to a surface layer of the workpiece. A larger workpiece can be produced by sequential “jetting” of melt layers made of particulate material.

Alternatively, a laser coating process can also be carried out in the mode of wire application welding, a wire being used instead of a powder. Correspondingly, the method according to the invention also comprises an embodiment in which a wire made of an aluminum alloy, as indicated above, is used.

For the method according to the invention, it was also found that heat treatment of the three-dimensional object produced can considerably improve its physical properties, for example in particular the tensile strength and / or the yield point. This effect may be due to rearrangements in the microstructure in the alloy of the initially formed three-dimensional object. For this purpose, the method according to the invention therefore preferably further comprises a step in which the initially produced three-dimensional object is subjected to a heat treatment, preferably at a temperature of 400 ° C. to 500 ° C. and / or for a time of 20 to 200 min. A range from 420 ° C. to 470 ° C. and in particular at least 430 ° C. and / or 450 ° C. or less can be mentioned as a particularly preferred temperature range. Particularly preferred time frames for the heat treatment are 30 minutes to 120 minutes and in particular at least 40 minutes and / or 80 minutes Or less. In addition, it has been found that such a heat treatment gives particularly advantageous results if, after such a heat treatment at a comparatively high temperature, the three-dimensional object is rapidly cooled to around ambient temperature (ie in 10 min or less and preferably 5 min or less, e.g. by quenching with What ser) and then aged at a temperature of 90 ° C to 150 ° C, in particular at least 110 ° C and / or at 140 ° C or less, for at least 12 hours and preferably at least 18 hours.

Another aspect of the present invention relates to a three-dimensional object which is produced using a powdered aluminum alloy, in particular produced according to the method described above, the powdered aluminum alloy being an aluminum alloy, as described above, and the three-dimensional object being such Comprises or consists of aluminum alloy. By using the alloys specified above for the production of such objects, very good "as built" surfaces can be obtained, so that subsequent post-treatment of the surface (e.g. smoothing) can be minimized.

The three-dimensional object according to the invention has expediently advantageously adapted mechanical properties, such as in particular a yield point of at least 400 MPa and / or at most 550 MPa, preferably at least 440 MPa to 550 MPa and particularly preferably in the range from 460 to 480 MPa and / or a tensile strength of 450 MPa and / or at most 550 MPa, preferably at least 470 MPa and particularly preferably in the range from 500 to 550 MPa. These respective yield strengths and strengths are to be determined within the scope of the invention described here in accordance with EN ISO 6892.1 (2011). Alternatively or additionally, a three-dimensional object according to the invention preferably has a yield point at 200 ° C. of preferably at least 330 MPa, more preferably at least 350 MPa and even more preferably in the range from 360 MPa to 420 MPa.

Another aspect of the present invention relates to a manufacturing device for performing a method for manufacturing a three-dimensional object, as stated above, the device being a laser sintering or laser melting device, a process chamber designed as an open container with a container wall, and one located in the process chamber Carrier, wherein the process chamber and carrier are movable relative to each other in the vertical direction, having a storage container and a layer movable in the horizontal direction, and wherein the storage container is at least partially filled with a powdered aluminum alloy, as stated above.

Analogously, the present invention relates to a manufacturing device for the implementation of a method for manufacturing a three-dimensional object, which has a device for laser coating and a process chamber, a feed device for feeding particulate material or wire into the area of action of the laser beam, and a storage container that contains at least is partially filled with a powdery aluminum alloy, as indicated above, or with wire of such an aluminum alloy.

Additive manufacturing devices for manufacturing three-dimensional objects and associated processes are generally characterized in that objects are manufactured in them layer by layer by solidifying a shapeless (or wire-shaped) building material. Solidification can be brought about, for example, by supplying thermal energy to the building material by irradiating it with electromagnetic radiation or particle radiation, for example during laser sintering ("SLS" or "DMLS") or laser melting or electron beam melting.

For example, with laser sintering or laser melting, the area of action of a laser beam ("laser spot") on a layer of the building material is moved over those points of the layer that correspond to the object cross-section of the object to be produced in this layer Building material can also be made by 3D printing, for example by applying an adhesive or binding agent.

Other features and embodiments of the invention can be found in the description of an exemplary embodiment with the aid of the accompanying drawings. FIG. 1 shows a schematic illustration, partially reproduced as a cross section, of a device for building up a three-dimensional object in layers according to an embodiment of the present invention.

The device shown in Figure 1 is a known laser sintering or laser melting device al. To build up an object a2, it contains a process chamber a3 with a chamber wall a4. In the process chamber a3, a construction container a5, which is open at the top and has a wall a6, is arranged. A working plane a7 is defined through the upper opening of the building container a5, the area of the working plane a7 lying within the opening, which can be used to build up the object a2, is referred to as building field a8. In the container a5 is a movable in a vertical direction V carrier aO is arranged, on which a base plate is all attached, which closes the building container a5 at the bottom and thus forms its bottom. The base plate a1 can be a plate formed separately from the carrier a10, which is fastened to the carrier a10, or it can be formed integrally with the carrier a10. Depending on the powder and process used, a construction platform a2 can also be attached to the base plate, on which the object a2 is built. The object a2 can also be built on the base plate itself, which then serves as a construction platform. In FIG. 1, the object a2 to be formed in the building container a5 on the building platform al2 is shown below the working plane a7 in an intermediate state with several solidified layers, surrounded by building material al3 that has remained unsolidified. The laser sintering device al further contains a storage container al4 for a powdery building material al5 which can be solidified by electromagnetic radiation and a coater al6 movable in a horizontal direction H for applying the building material al5 to the building field a8. The laser sintering device a1 also contains an exposure device a20 with a laser a21, which generates a laser beam a22 as an energy beam, which is deflected via a deflection device a23 and through a focusing device a24 via a coupling window a25 which is attached to the top of the process chamber a3 in its wall a4 , is focused on the working plane a7.

Furthermore, the laser sintering device a1 contains a control unit a29, via which the individual components of the device a1 are controlled in a coordinated manner in order to carry out the construction process. The control unit a29 may contain a CPU, the operation of which is controlled by a computer program (software). The computer program can be stored separately from the device on a storage medium from which it can be loaded into the device, in particular into the control unit. In operation, to apply a powder layer, the carrier a10 is first lowered by a height that corresponds to the desired layer thickness. By moving the coater al6 over the working plane a7, a layer of the powdery build-up material al5 is then applied. To be on the safe side, the coater al6 pushes a somewhat larger amount of build-up material a5 in front of him than is necessary for building up the layer. The coater al6 pushes the planned surplus of construction material al5 into an overflow container al8. An overflow container al8 is arranged on both sides of the building container a5. The application of the powdery building material al5 takes place at least over the entire cross section of the object a2 to be produced, preferably over the entire construction field a8, that is the area of the working plane a7, which can be lowered by a vertical movement of the carrier alO. The cross-section of the object a2 to be produced is then scanned by the laser beam a22 with a radiation area (not shown) which schematically represents an intersection of the energy beam with the working plane a7. As a result, the powdery building material al5 is solidified at points which correspond to the cross section of the object a2 to be produced. These steps are repeated until the object a2 is completed and the building container a5 can be removed. To generate a preferably laminar process gas flow a34 in the process chamber a3, the laser sintering device a1 further contains a gas supply channel a32, a gas inlet nozzle a30, a gas outlet opening a31 and a gas discharge channel a33. The process gas flow a34 moves horizontally over the construction field a8. The gas supply and discharge can also be controlled by the control unit a29 (not shown). The gas extracted from the process chamber a3 can be fed to a filter device (not shown), and the filtered gas can be fed back to the process chamber a3 via the gas feed channel a32, thereby forming a circulating air system with a closed gas circuit. Instead of just one gas inlet nozzle a30 and one gas outlet opening a31, several nozzles or openings can also be provided.

In the device according to the invention, the storage container al4 is at least partially filled with a powdery aluminum alloy al5, as indicated above. A further aspect of the present invention finally relates to an aluminum alloy with a content of 4 to 6% by weight Cu, 0.1 to 1.5% by weight Mg and 0.1 to 1% by weight Ag, and 1 , 3 to 15% by weight of metals selected from the group Ml comprising Mo, Nb, Zr, Fe, Ti, Ta, V, and lanthanoids, with the proportion of the alloy on aluminum, which is missing to 99% by weight, being preferred is omitted and, more preferably, the proportion of the alloy, which is missing by 100% by weight, is made up of aluminum, manganese, silicon and oxygen.

The present invention is further illustrated by a few examples, which, however, should not be interpreted as being in any way relevant to the scope of protection of this application.

Example 1:

Various aluminum alloys with the compositions given in Table 1 were processed into test specimens by means of direct metal laser sintering (DMLS). The test specimens produced in this way were tested for their hardness,

Yield strength at 23 ° C and tensile strength investigated. The results of these investigations are also given in Table 1.

¹ = as manufactured; ² = after heat treatment.

To determine the hardness, the test specimen produced was subjected to the Brinell method in accordance with the standard DIN EN ISO 6506-1: 2015 "Metallic materials - Brinell hardness test - Part 1: Test method". Density cube samples were used for the determination. The tests are done three times for each sample and the measured values are reported with an accuracy of 1 HBW.

The test body produced in comparative sample 1 exhibited massive hot cracks. In comparative sample 2, the hot cracks were considerably reduced compared to comparative sample 1, but were still recognizable; a heat treatment of the test body did not lead to an improvement in the hardness of the material. The material according to the invention showed no hot cracks and, compared with the comparison samples, mechanical properties were considerably improved even immediately after production. By heat treatment (485 ° C / 40 min and subsequent quenching with water and aging at 25 ° C) these properties could be improved considerably.

Example 2:

A test body produced from the aluminum alloy according to Example 1 (- · -) was compared with respect to its yield strength properties with corresponding test bodies made of other materials. As comparison materials, test bodies made of Scalmalloy (DMLS processed, -o-), the aluminum alloy AW2618 (forged, T6, - _□ -), the aluminum alloy 7075 (T6, -A-), the aluminum alloy 2024 (T6, -x-) and Addmalloy (DMLS processed, -o-) used. The data of the comparative materials are taken from the literature or the corresponding data sheets. The yield strengths of test specimens made from these materials are shown in FIG.

From FIG. 2 it can be seen that the aluminum alloy according to the invention already had the highest yield point of all tested materials at 23 ° C., only Scalmalloy and the aluminum alloy 7075 exhibiting a yield point in a similarly high range. Compared to the high-temperature-resistant kneading alloy AW-2618A, the difference was about 27%. From a temperature of around 100 to 120 ° C, the yield strength of the 7075 aluminum alloy drops sharply, while that of Scalmalloy is even significantly lower at these temperatures. In contrast, the yield strength of the aluminum alloy according to the invention only decreases slightly at these temperatures. At around 200 ° C., the aluminum alloy according to the invention has a yield point that is around 42% better than the second best alloy AW 2618A.

Claims

Expectations

1. Powdery aluminum alloy with Cu, Zn or Si / Mg as the most relevant alloy element, characterized in that the alloy furthermore has a content of 1 to 15% by weight of metals selected from the group Ml comprising Mo, Nb, Zr, Fe, Ti , Ta, V, and lanthanoids.

2. Powdered aluminum alloy according to claim 1, characterized in that it has a content of at least 1.3% by weight, preferably 2.0% by weight up to 8.0% by weight, and more preferably 2.5 % By weight up to 5.0% by weight of metals of group Ml, preferably of Zr and / or Ti.

3. Powdery aluminum alloy according to claim 1 or 2, wherein the aluminum alloy has a content of 4 to 6 wt .-% Cu, 0.1 to 1.5 wt .-% Mg and 0.1 to 1 wt .-% Ag , and where the portion of the alloy, which is 99% by weight, is preferably aluminum.

4. Powdered aluminum alloy according to claim 3 with a content of at least 4.5% by weight and / or at most 5.8% by weight, preferably at least 4.8% by weight and / or at most 5.5% by weight. -% Cu, at least 0.2% by weight and / or at most 1.5% by weight, preferably at least 0.3% by weight and / or at most 1.2% by weight Mg, and at least 0, 05% by weight and / or at most 0.6% by weight, preferably at least 0.2% by weight and / or at most 0.4% by weight Ag.

5. Powdery aluminum alloy according to claim 3, further comprising up to 0.2 wt .-%, preferably 0.05 to 0.15 wt .-% oxygen, up to 0.6 wt .-%, preferably 0.2 to 0 , 55 wt .-% manganese and up to 0.3 wt .-%, preferably 0.05 to 0.15 wt .-% silicon.

6. Powdered aluminum alloy according to one of claims 1 to 5, characterized in that it has an average particle size d50 in the range from 0.1 to 500 pm, preferably of at least 1 and / or at most 200 pm, particularly preferably at least 10 and / or at most 80 pm.

7. Powdered aluminum alloy according to one of claims 1 to 5, characterized in that it has a content of metal borides, nitrides and carbides of less than 0.2% by weight, preferably less than 0.1% by weight and more preferably less than 0.05 wt%.

8. The method for producing a powdery aluminum alloy according to any one of the preceding claims, characterized in that the method includes a step of atomizing the liquid alloy at a temperature of> 850 ° C and preferably> 1050 ° C, or a step of mechanical alloying, and possibly includes post-processing.

9. A method for producing a three-dimensional object, the object being produced by applying a building material layer on layer and selectively solidifying the building material, in particular by means of supplying radiant energy, at points in each layer that are assigned to the cross-section of the object in this layer are, preferably in that the points are scanned with at least one area of action, in particular a radiation area of action of an energy beam, or by bringing the construction material into the radiation exposure area and melting it and applying it to a substrate, the construction material being a powdery aluminum alloy according to one of claims 1 to 7 or a corresponding wire-shaped aluminum alloy and preferably consists of this.

10. The method according to claim 9, wherein the powdered aluminum alloy is preheated, preferably to a temperature of at least 100 ° C, particularly preferably at most 400 ° C.

11. The method according to claim 9 or 10, wherein the manufactured three-dimensional object is subjected to a heat treatment, preferably at a temperature of 400 ° C to 500 ° C, and / or for a period of 20 to 200 minutes.

12. Three-dimensional object produced using a pulverförmi gene aluminum alloy, in particular produced by a method according to claim 8, wherein the powdered aluminum alloy is an aluminum alloy as specified in one of claims 1 to 7 and where in the three-dimensional object comprises such an aluminum alloy or from this exists.

13. Three-dimensional object according to claim 12, characterized in that it has a yield strength of at least 400 MPa and / or at most 550 MPa, preferably at least 440 MPa and particularly preferably in the range of 460 to 500 MPa and / or a tensile strength of 450 MPa, preferably at least 470 MPa and / or at most 550 MPa and particularly preferably in the range from 500 to 550 MPa.

14. Manufacturing device for performing a method according to claim 9, wherein the device is a laser sintering or laser melting device, a process chamber which is an open container with a container wall, a carrier located in the process chamber, the process chamber and carrier against each other in the vertical direction are movable, comprises a storage container and a horizontally movable loading layer, and wherein the storage container is at least partially filled with a powdery aluminum alloy according to one of claims 1 to 7.

15. Aluminum alloy with a content of 4 to 6% by weight Cu, 0.1 to 1.5% by weight Mg and 0.1 to 1% by weight Ag, and 1.3 to 15% by weight of metals selected from the group Ml comprising Mo, Nb, Zr, Fe, Ti, Ta, V, and lanthanides, where the 99% by weight missing portion of the alloy is preferably aluminum and more preferably the 100% by weight missing portion of the alloy is aluminum, manganese, silicon and oxygen.