METHOD FOR MANUFACTURING AN ALUMINUM ALLOY PART

Abstract

Additive manufacturing process, applied to the following aluminium alloy composition, in mass percentages: - at least one alloying element chosen from: Zr, Hf, Sc and Er, according to a mass fraction of 0.40 to 1.60% each and / or in total; - Fe, according to a mass fraction of 0.50 to 3.00%; - Cr, according to a mass fraction of 1.00 to 4.00%. Figure 1

Description

Title of the invention: METHOD FOR MANUFACTURING AN ALUMINUM ALLOY PART Technical field

[0001] The technical field of the invention is a method for manufacturing an aluminum alloy part, implementing an additive manufacturing technique. Prior art

[0002] Since the 1980s, additive manufacturing techniques have been developed. They consist of shaping a part by adding material, which is the opposite of machining techniques, which aim to remove material. Once confined to prototyping, additive manufacturing is now operational for mass-producing industrial products, including metal parts.

[0003] The term "additive manufacturing" is defined according to the French standard XP E67-001 as a "set of processes for manufacturing, layer by layer, by adding material, a physical object from a digital object". The ASTM F2792 standard (January 2012) also defines additive manufacturing. Different additive manufacturing methods are also defined and described in the ISO / ASTM 17296-1 standard. The use of additive manufacturing to produce an aluminum part, with low porosity, has been described in document WO2015006447. The application of successive layers is generally carried out by applying a so-called filler material, then melting or sintering the filler material using an energy source such as a laser beam, electron beam, plasma torch or electric arc. Whatever the additive manufacturing method applied, the thickness of each added layer is of the order of a few tens or hundreds of microns.

[0004] Other additive manufacturing methods can be used. For example, and without limitation, the melting or sintering of a filler material in the form of a powder. This may involve laser melting or sintering. Patent application US20170016096 describes a method for manufacturing a part by localized melting obtained by exposing a powder to an energy beam of the electron beam or laser beam type, the method also being called laser powder bed fusion or electron beam melting.

[0005] Those skilled in the art know solutions which allow thermal stability of the mechanical properties, but which are not necessarily suitable for high temperatures (see for example patent application WO202 / 070451, which discloses an alloy comprising from 1 to 10% of Fe, from 1 to 10% of Cr and optionally up to 4 % of Zr, Hf, Er, Sc and / or Ti).

[0006] The mechanical properties of aluminum parts obtained by additive manufacturing depend on the alloy forming the filler metal, and more precisely on its composition as well as the heat treatments applied following the implementation of additive manufacturing.

[0007] The applicant has determined an alloy composition which, when used in an additive manufacturing process, makes it possible to obtain parts with remarkable mechanical performance, without it being necessary to implement heat treatments such as solution treatment and quenching.

[0008] According to a variant of the present invention, with a judicious choice of the addition elements, the applicant has identified aluminum alloy compositions intended for additive manufacturing processes making it possible to obtain both very good processability of the parts, in particular in processes of the powder bed laser fusion type, and excellent mechanical performance of the parts in service, whether at room temperature or at high temperature, i.e. for temperatures greater than or equal to 200°C. The excellent mechanical performance of the parts in service can be obtained by maximizing the elastic limit of the parts at room temperature and at 200°C, after a post-manufacturing heat treatment, for example from 1 h to 400°C. By way of illustration, the elastic limit Rp0.2 obtained can be greater than or equal to 350 MPa at 25°C and greater than or equal to 200 MPa at 200°C.

[0009] Pure aluminum powders can be used as a reducing agent in the solid propellant of aerospace thrusters. Therefore, aluminum powders with more than 97% aluminum are generally considered in some countries as dual-use goods (DUG) requiring export licenses. This classification represents a constraint that can hinder the commercialization of certain aluminum powders comprising more than 97% aluminum intended for the additive manufacturing process, such as LPBF. It thus appears advantageous that the developed solution has less than 97% aluminum, i.e. more than 3% of additive elements in total.

[0010] According to another variant of the present invention, with a judicious choice of the addition elements, the applicant has identified compositions of aluminum alloys intended for additive manufacturing processes, in particular LPBF, these compositions comprising more than 3% of addition elements in total and allowing good processability of the parts in the LPBF process, while maximizing the mechanical performance of the parts in service. Statement of the invention

[0011] A first object of the invention is a method of manufacturing a part comprising a formation of successive metallic layers, superimposed on each other, each layer being formed by the deposition of a filler metal, the filler metal being subjected to an energy input so as to melt and to constitute, by solidifying, said layer, the process being characterized in that the filler metal is an aluminum alloy comprising the following alloying elements in mass percentages: - at least one alloying element chosen from: Zr, Hf, Sc and Er, according to a mass fraction of 0.40% to 1.60%, preferably 0.50 to 1.50%, preferably 0.55 to 1.40%, preferably 0.60 to 1.30%, preferably 0.60 to 1.25%, preferably 0.60 to 1.20%, preferably 0.60 to 1.00%, preferably 0.60 to 0.95%, preferably 0.65 to 0.90% each and / or in total; - Fe, in a mass fraction of 0.50 to 3.00%, preferably 0.60 to 2.80%, preferably 0.70 to 2.70%, preferably 0.80 to 2.70%, preferably 0.90 to 2.60%, preferably 0.90 to 2.50%, preferably 0.90 to 2.40%, preferably 0.90 to 2.30%, preferably 0.90 to 2.20%; - Cr, according to a mass fraction of 1.00 to 4.00%, preferably 1.50 to 3.80%, preferably 1.60 to 3.70%, preferably 1.70 to 3.60%, preferably 1.75 to 3.50%, preferably 1.75 to 3.40%, preferably 1.75 to 3.30%, preferably 1.75 to 3.20%, preferably 1.80 to 3.20%, preferably 1.90 to 3.20%; - optionally at least one alloying element chosen from: Mn, V and Ti according to a mass fraction greater than or equal to 0.03%, preferably greater than or equal to 0.05%, preferably from 0.10 to 3.00%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.40%, preferably from 0.40 to 2.30%, preferably from 0.40 to 2.20%, preferably from 0.40 to 2.10%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.90%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.70%, preferably from 0.40 to 1.60% each and / or in total; - optionally Mg, according to a mass fraction greater than or equal to 0.03%, preferably from 0.05 to 3.50%, preferably from 0.10 to 3.40%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.30%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.60%; - optionally If, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally Ni, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.05 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.50%, preferably 0.10 to 1.40%, preferably 0.10 to 1.30%, preferably 0.10 to 1.20%, preferably 0.10 to 1.10%, preferably 0.10 to 1.00%, preferably 0.10 to 0.90%, preferably 0.10 to 0.80%, preferably 0.10 to 0.70% each and / or in total; - optionally at least one alloying element chosen from: Zn and Li, according to a mass fraction of less than 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30% each and / or in total; - optionally at least one alloying element chosen from: Co, La, Ce, mi-schmetal, W, Ta, Mo, Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, according to a mass fraction less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30%, even more preferably less than or equal to 0.10% each, and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30% in total; - impurities: < 0.05% individually, and preferably < 0.15% in total; remainder aluminum.

[0012] Each layer can in particular describe a pattern defined from a digital model.

[0013] According to one embodiment, the filler metal takes the form of a powder, the exposure of which to a beam of light or charged particles results in localized melting followed by solidification, so as to form a solid layer. According to another embodiment, the filler metal comes from a filler wire, the exposure of which to a heat source, for example an electric arc, results in localized melting followed by solidification, so as to form a solid layer.

[0014] A second object of the invention is a metal part, obtained by a method according to the first object of the invention.

[0015] A third subject of the invention is a filler material, in particular a filler wire or a powder, intended to be used as a filler material in an additive manufacturing process, characterized in that it is made of an aluminum alloy, comprising the following alloying elements (% by weight): - at least one alloying element chosen from: Zr, Hf, Sc and Er, according to a mass fraction of 0.40% to 1.60%, preferably 0.50 to 1.50%, preferably 0.55 to 1.40%, preferably 0.60 to 1.30%, preferably 0.60 to 1.25%, preferably 0.60 to 1.20%, preferably 0.60 to 1.00%, preferably 0.60 to 0.95%, preference of 0.65 to 0.90% each and / or in total; - Fe, in a mass fraction of 0.50 to 3.00%, preferably 0.60 to 2.80%, preferably 0.70 to 2.70%, preferably 0.80 to 2.70%, preferably 0.90 to 2.60%, preferably 0.90 to 2.50%, preferably 0.90 to 2.40%, preferably 0.90 to 2.30%, preferably 0.90 to 2.20%; - Cr, according to a mass fraction of 1.00 to 4.00%, preferably 1.50 to 3.80%, preferably 1.60 to 3.70%, preferably 1.70 to 3.60%, preferably 1.75 to 3.50%, preferably 1.75 to 3.40%, preferably 1.75 to 3.30%, preferably 1.75 to 3.20%, preferably 1.80 to 3.20%, preferably 1.90 to 3.20%; - optionally at least one alloying element chosen from: Mn, V and Ti according to a mass fraction greater than or equal to 0.03%, preferably greater than or equal to 0.05%, preferably from 0.10 to 3.00%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.40%, preferably from 0.40 to 2.30%, preferably from 0.40 to 2.20%, preferably from 0.40 to 2.10%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.90%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.70%, preferably from 0.40 to 1.60% each and / or in total; - optionally Mg, according to a mass fraction greater than or equal to 0.03%, preferably from 0.05 to 3.50%, preferably from 0.10 to 3.40%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.30%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.60%; - optionally If, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally Ni, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.05 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.50%, preferably 0.10 to 1.40%, preferably 0.10 to 1.30%, preferably 0.10 to 1.20%, preferably 0.10 to 1.10%, preferably 0.10 to 1.00%, preferably 0.10 to 0.90%, preferably 0.10 to 0.80%, preferably 0.10 to 0.70% each and / or in total; - optionally at least one alloying element chosen from: Zn and Li, according to a mass fraction of less than 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30% each and / or in total; - optionally at least one alloying element chosen from: Co, La, Ce, mi-schmetal, W, Ta, Mo, Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, according to a mass fraction less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30%, even more preferably less than or equal to 0.10% each, and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30% in total; - impurities: <0.05% individually, and in total <0.15%; remainder aluminum.

[0016] The aluminum alloy forming the filler material may have the characteristics described in connection with the first subject of the invention.

[0017] The filler material may be in the form of a powder. The powder may be such that at least 80% of the particles comprising the powder have an average size in the following range: 5 pm to 200 pm, preferably 5 to 150 pm, preferably 5 to 25 pm, or 20 to 60 pm or 20 to 80 pm or 20 to 90 pm or 20 to 100 pm or 20 to 110 pm or 20 to 120 pm.

[0018] When the filler material is in the form of a wire, the diameter of the wire may in particular be from 0.5 mm to 3 mm, and preferably from 0.5 mm to 2 mm, and more preferably from 1 mm to 2 mm.

[0019] A fourth object of the invention is the use of a powder or a filler wire as described above and in the rest of the description in a manufacturing process chosen from: electron beam melting, cold spraying, laser fusion deposition, additive manufacturing by friction, plasma spark sintering or rotary friction welding, preferably cold spraying.

[0020] Other advantages and characteristics will emerge more clearly from the following description of particular embodiments of the invention, given as non-limiting examples, and represented in the figures listed below. Figures

[0021] [Fig-1] [Fig.l] is a diagram illustrating an additive manufacturing process of the type laser powder bed fusion. [Fig.2] [Fig.2] is a diagram illustrating an additive manufacturing process of the arc wire additive manufacturing type. [Fig.3] [Fig.3] is a diagram of the test piece used according to the examples. [Fig.4] [Fig.4] shows a cracking specimen as used in the examples. Reference 1 corresponds to the face used for metallo- graphics, reference 2 to the manufacturing direction. Presentation of specific embodiments

[0022] In the description, unless otherwise indicated: - the designation of aluminum alloys is in accordance with the nomenclature of The Aluminum Association; - the chemical element contents are designated in % and represent mass fractions. The notation x% - y% means greater than or equal to x% and less than or equal to y%.

[0023] By impurities we mean chemical elements present in the alloy unintentionally.

[0024] [Fig.l] shows schematically the operation of an additive manufacturing process of the selective fusion type by laser on a powder bed (or Laser Powder Bed Fusion). The filler metal 15 is in the form of a powder arranged on a support 10. An energy source, in this case a laser source 11, emits a laser beam 12. The laser source is coupled to the filler material by an optical system 13, the movement of which is determined according to a digital model M. The laser beam 12 propagates along a propagation axis Z, and follows a movement along an XY plane, describing a pattern dependent on the digital model M. The plane is for example perpendicular to the propagation axis Z. The interaction of the laser beam 12 with the powder 15 causes a selective fusion of the latter, followed by solidification, resulting in the formation of a layer 20i.. .20n.When a layer has been formed, it is covered with powder 15 of the filler metal and another layer is formed, superimposed on the layer previously produced. The thickness of a layer can for example be from 10 to 250 pm, for example 30 pm, or 60 pm, or 80 pm, or 90 pm, or 100 pm, or 110 pm, or 120 pm, or 130 pm, or 140 pm, or 150 pm, or 160 pm, or 170 pm, or 180 pm, or 190 pm, or 200 pm.

[0025] An increase in layer thickness may be beneficial for increasing productivity during printing and for limiting sensitivity to thermal cracking related to residual stresses during part manufacturing and / or during post-manufacturing heat treatment. An increase in layer thickness may be accompanied by an adaptation of the laser power and the vector gap (distance between two successive laser passes) and the laser scanning speed in order to ensure complete melting of each powder layer under optimal conditions. The layer thickness may be, for example, from 60 to 250 μm, preferably from 80 to 200 μm, preferably from 90 to 180 μm, preferably from 100 to 180 μm, preferably from 110 to 170 μm, preferably from 120 to 160 μm.

[0026] For aluminum alloys, the support 10 or plate can be heated to a preheating temperature T of up to 500°C. The machines available ac Currently on the market generally offer plate heating up to 200°C. The plate heating temperature (= preheating temperature T) can be, for example, around 50°C, 100°C, 150°C, 200°C, 250°C, 300°C or 350°C or 400°C or 450°C or 500°C. Plate heating generally reduces the humidity in the powder bed and also reduces residual stresses on the parts being manufactured. The humidity level in the powder bed seems to have a direct effect on the porosity of the final part. Indeed, it seems that the higher the humidity of the powder, the higher the porosity of the final part. It should be noted that plate heating is one of the existing possibilities for carrying out hot additive manufacturing. However, the present invention cannot be limited to the use of this heating means alone.Any other heating means, allowing this preheating step to be carried out, may be used within the scope of the present invention for heating and controlling the temperature, for example an infrared lamp. Thus, the method according to the present invention may be carried out at a preheating temperature T of up to 500°C.

[0027] For certain compositions, the inventors have found that when the preheating temperature T of the powder bed is less than or equal to 160°C and greater than or equal to 25°C, the parts have better resistance to thermal cracking linked to residual stresses. Preferably, the preheating of the powder bed can be carried out at a preheating temperature T less than or equal to 140°C, or, better, less than or equal to 130°C. The preheating temperature T is higher than ambient temperature. The preferred preheating temperature ranges T of the powder bed are: 25°C < T < 160°C, preferably 30°C < T < 150°C, preferably 50°C < T < 150°C, preferably 50°C < T < 140°C, preferably 60°C < T < 140°C, preferably 70°C < T < 135°C, preferably 80°C < T < 130°C.

[0028] According to an alternative, the preheating temperature T corresponds to the conditions under which effective relaxation can be obtained. The preheating temperature range T can then be from 300°C to 500°C, preferably from 300 to 400°C, preferably from 300 to 350°C. It is considered that at this preheating temperature range T, the manufacturing conditions of the part generate fewer residual stresses. According to this alternative, a post-manufacturing relaxation heat treatment, as described below in the present description, is also relevant.

[0029] The powder according to the present invention may have at least one of the following characteristics: - Average particle size from 5 pm to 200 pm, preferably from 5 to 150 pm, preferably from 5 to 25 pm, or from 20 to 60 pm, or from 20 to 80 pm, or from 20 to 90 pm, or from 20 to 100 pm, or from 20 to 110 pm, or from 20 to 120 pm. The given values ​​mean that at least 80% of the particles have an average size in the specified range. - Spherical shape. The sphericity of a powder can, for example, be determined using a morphogranulometer. - Good flowability. The flowability of a powder can, for example, be determined according to ASTM B213 or ISO 4490:2018. According to ISO 4490:2018, the flow time is preferably less than 50. - Low porosity, preferably 0 to 5%, more preferably 0 to 2%, even more preferably 0 to 1% by volume. Porosity can be determined, in particular, by image analysis from optical micrographs or by helium pycnometry (see ASTM B923). - Absence or low quantity (less than 10%, preferably less than 5% by volume) of small particles (1 to 20% of the average size of the powder), called satellites, which stick to the larger particles.

[0030] The implementation of such a method allows the manufacturing of parts with a high yield, which can reach or even exceed 200 cmVh per laser.

[0031] Furthermore, the applicant observed that the application of post-manufacturing heat treatments of the quenching type could induce distortion of the part, due to the sudden variation in temperature. The distortion of the part is generally all the more significant as its dimensions are large. However, the advantage of an additive manufacturing process is precisely to obtain a part whose shape, after manufacturing, is definitive or quasi-definitive. The occurrence of significant deformation resulting from a post-manufacturing heat treatment is therefore to be avoided. By quasi-definitive, it is understood that finishing machining can be carried out on the part after its manufacturing: the part manufactured by additive manufacturing extends according to its definitive shape, apart from the finishing machining.

[0032] Having noted the above, the applicant sought an alloy composition, forming the filler material, making it possible to obtain acceptable mechanical properties and electrical or thermal conductivity, without requiring the application of heat treatments, subsequent to the formation of the layers, that is to say following the formation of the final part, which risk inducing distortion. This involves in particular avoiding heat treatments involving a sudden variation in temperature. Thus, the invention makes it possible to obtain, by additive manufacturing, a part whose mechanical properties, in particular in terms of elastic limit, and electrical or thermal conductivity, are satisfactory. Depending on the type of additive manufacturing process chosen, the filler material may be in the form of a wire or a powder.

[0033] The following elements can be used in the aluminum alloy. Zr, Hf, Sc and / or Er:

[0034] According to the present invention, at least one alloying element chosen from: Zr, Hf, Sc and Er is present in the aluminum alloy in a mass fraction of 0.40% to 1.60%, preferably 0.50 to 1.50%, preferably 0.55 to 1.40%, preferably 0.60 to 1.30%, preferably 0.60 to 1.25%, preferably 0.60 to 1.20%, preferably 0.60 to 1.00%, preferably 0.60 to 0.95%, preferably 0.65 to 0.90% each and / or in total. Preferably, the mass fraction of at least one alloying element selected from: Zr, Hf, Sc and Er is greater than or equal to 0.40%, or 0.45%, or 0.50%, or 0.55%, or 0.60%, or 0.65% each and / or in total. Preferably, the mass fraction of at least one alloying element chosen from: Zr, Hf, Sc and Er is less than or equal to 1.60%, or 1.55%, or 1.50%, or 1.45%, or 1.40%, or 1.35%, or 1.30%, or 1.25%, or 1.20%, or 1.15%, or 1.10%, or 1.05%, or 1.00%, or 0.95%, or 0.90% each and / or in total.

[0035] These elements have a high solubility in the as-manufactured state. Their addition can thus significantly lower the conductivity in the as-manufactured state. However, the addition of a post-manufactured heat treatment, for example at a temperature of 300 to 450°C, for durations of 0.5 to 10 hours, can significantly lower their solid solution contents by the formation of hardening dispersoids of type A13X (X= Zr or Hf or Sc or Er). The formation of these dispersoids during the heat treatment can simultaneously increase the hardness and the electrical conductivity compared to the as-manufactured state.

[0036] These elements can also make it possible to control the granular structure during laser melting by promoting the appearance of equiaxed grains.

[0037] Furthermore, the presence of at least one alloying element chosen from: Zr, Hf, Sc and Er in the alloy can confer good processability to the alloy, the term processability corresponding to the Anglo-Saxon designation "processability", qualifying the ability of an alloy to be shaped by an additive manufacturing process. This can result, at the level of a part manufactured by additive manufacturing, in a virtual absence of defects, such as solidification cracking, and low porosity. Fe:

[0038] According to the present invention, the element Fe is present in the aluminum alloy in a mass fraction of 0.50 to 3.00%, preferably 0.60 to 2.80%, preferably 0.70 to 2.70%, preferably 0.80 to 2.70%, preferably 0.90 to 2.60%, preferably 0.90 to 2.50%, preferably 0.90 to 2.40%, preferably 0.90 to 2.30%, preferably 0.90 to 2.20%. Preferably, the mass fraction of Fe is greater than or equal to 0.50%, or 0.55%, or 0.60%, or 0.65%, or 0.70%, or 0.75%, or 0.80%, or 0.85%, or 0.90%. Preferably, the mass fraction of Fe is less than or equal to 3.00%, or 2.95%, or 2.90%, or 2.85%, or 2.80%, or 2.75%, or 2.70%, or 2.65%, or 2.60%, or 2.55%, or 2.50%, or 2.45%, or 2.40%, or 2.35%, or 2.30%, or 2.25%, or 2.20%.

[0039] This element can increase the mechanical strength of the alloy by solid solution and / or by dispersoids which can form during the manufacture of the part or during post-manufacturing heat treatments. This element has low solubility in aluminum. The addition of this element makes it possible to increase the elastic limit, but an excessive addition of Fe, i.e. at contents greater than or equal to 3.00%, can lead to an increase in sensitivity to cracking and lower the elongation at break. Cr:

[0040] According to the present invention, the element Cr is present in the aluminum alloy in a mass fraction of 1.00 to 4.00%, preferably 1.50 to 3.80%, preferably 1.60 to 3.70%, preferably 1.70 to 3.60%, preferably 1.75 to 3.50%, preferably 1.75 to 3.40%, preferably 1.75 to 3.30%, preferably 1.75 to 3.20%, preferably 1.80 to 3.20%, preferably 1.90 to 3.20%. Preferably, the mass fraction of Cr is greater than or equal to 1.00%, or 1.05%, or 1.10%, or 1.15%, or 1.20%, or 1.25%, or 1.30%, or 1.35%, or 1.40%, or 1.45%, or 1.50 %, or 1.55%, or 1.60%, or 1.65%, or 1.70%, or 1.75%, or 1.80%, or 1.85%, or 1.90%. Preferably, the mass fraction of Cr is less than or equal to 4.00%, or 3.95%, or 3.90%, or 3.85%, or 3.80%, or 3.75%, or 3.70%, or 3.65%, or 3.60 %, or 3.55%, or 3.50%, or 3.45%, or 3.40%, or 3.35%, or 3.30%, or 3.25%, or 3.20%.

[0041] This element can make it possible to increase the mechanical strength of the alloy by solid solution and / or by dispersoids which can form during the manufacture of the part or during post-manufacturing heat treatments. The addition of this element can make it possible to increase the elastic limit at room temperature and at high temperature, this effect being accentuated by the presence of Fe in the alloy. Thus a simultaneous addition of Cr and Fe can be advantageous for increasing the mechanical strength at room temperature and at high temperature (temperature greater than or equal to 200°C).

[0042] Excessive addition of Cr, i.e. at mass fractions greater than or equal to 4.00%, can lead to an increase in sensitivity to cracking and lower the elongation at break.

[0043] Cr has a low diffusion coefficient in aluminum which can provide high thermal stability to the alloy.

[0044] Cr has a high solubility in aluminum and has a negative impact on conductivity. The use of this element is of interest for alloys targeting certain applications that do not require particular performance in terms of electrical or thermal conductivity but which require high mechanical strength, such as structural parts, hydraulic blocks, etc. Mn, V and / or Ti:

[0045] According to the present invention, at least one alloying element chosen from: Mn, V and Ti may be present in the aluminum alloy in a mass fraction greater than or equal to 0.03%, preferably greater than or equal to 0.05%, preferably from 0.10 to 3.00%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.40%, preferably from 0.40 to 2.30%, preferably from 0.40 to 2.20%, preferably from 0.40 to 2.10%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.90%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.70%, preferably from 0.40 to 1.60% each and / or in total. Preferably, the mass fraction of at least one alloying element selected from Mn, V and Ti is greater than or equal to 0.03%, or 0.05%, or 0.10%, or 0.15%, or 0.20%, or 0.25%, or 0.30%, or 0.35%, or 0.40%, each and / or in total.Preferably, the mass fraction of at least one alloying element chosen from: Mn, V and Ti is less than or equal to 3.00%, or 2.90%, or 2.80%, or 2.70%, or 2.60%, or 2.50%, or 2.40%, or 2.30%, or 2.20%, or 2.10%, or 2.00%, or 1.90%, or 1.80%, or 1.70%, or 1.60% each and / or in total.

[0046] These elements can make it possible to increase the mechanical resistance of the alloy at room temperature and at high temperature by solid solution and / or by dis-persoids which can form during the manufacture of the part or during post-manufacturing heat treatments. These elements have a low diffusion coefficient in the aluminum which makes it possible to offer high thermal stability to the alloy.

[0047] These elements have a high solubility in aluminum and have a negative impact on conductivity. The addition of these elements is of interest for alloys targeting certain applications that do not require particular performance in terms of electrical or thermal conductivity but which require high mechanical strength, such as structural parts, hydraulic blocks, etc.

[0048] Excessive addition of these elements can increase the sensitivity to cracking of the alloy, thus according to one variant the content of these elements is kept below 3.00% each and / or in total. Mg:

[0049] According to the present invention, the element Mg may be present in the aluminum alloy in a mass fraction greater than or equal to 0.03%, preferably from 0.05 to 3.50%, preferably from 0.10 to 3.40%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.30%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.60%.

[0050] Preferably, the mass fraction of Mg is greater than or equal to 0.03%, or 0.05%, or 0.10%, or 0.15%, or 0.20%, or 0.25%, or 0.30%, or 0.35%, or 0.40%. Preferably, the mass fraction of Mg is less than or equal to 3.50%, or 3.40%, or 3.30%, or 3.20%, or 3.10%, or 3.00%, or 2.90%, or 2.80%, or 2.70%, or 2.60%, or 2.50%, or 2.40%, or 2.30%, or 2.20%, or 2.10%, or 2.00%, or 1.90%, or 1.80%, or 1.70, or 1.60%.

[0051] This element can increase the mechanical strength of the alloy by solid solution. It can also, counter-intuitively, improve crack resistance. Excessive addition of this element, for example at contents greater than or equal to 3.5%, can degrade intergranular corrosion resistance, by the formation of the anodic phase [3 (Mg5Al8) at the grain boundaries. The formation of this phase can occur at room temperature and its formation can be accelerated for temperatures greater than or equal to 60°C.

[0052] This element is sensitive to evaporation during laser melting, which can lead to the formation of fumes and instabilities of the melt pools. This evaporation must be taken into account to adjust the Mg content in the powder according to the Mg content targeted on the part. If:

[0053] According to the present invention, the element Si may be present in the aluminum alloy in a mass fraction of less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; in one embodiment, the Si content is less than or equal to 0.30%, preferably less than or equal to 0.20%. According to a variant, the element Si may be present in the aluminum alloy in a mass fraction of greater than or equal to 500 ppm, or greater than or equal to 0.10%, or greater than or equal to 0.15%.

[0054] Preferably, the mass fraction of Si is less than or equal to 3.00%, or 2.90%, or 2.80%, or 2.70%, or 2.60%, or 2.50%, or 2.40%, or 2.30%, or 2.20%, or 2.10%, or 2.00%, or 1.90%, or 1.80%, or 1.70%, or 1.60%, or 1.50%, or 1.40%, or 1.30%, or 1.20%, or 1.10%, or 1.00%, or 0.90%, or 0.80%, or 0.70%, or 0.60, or 0.50%.

[0055] This element can make it possible to increase the mechanical resistance of the alloy by solid solution and / or by precipitates or dispersoids which can form during the manufacture of the part or during post-manufacturing heat treatments. This element can have a beneficial effect by lowering the sensitivity to cracking.

[0056] The addition of Si in the presence of Zr can lead to the formation of coarse AlZrSi phases which would limit the hardening power of Zr after heat treatment. Neither:

[0057] According to the present invention, the element Ni may be present in the aluminum alloy in a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%. According to a variant, the element Ni may be present in the aluminum alloy in a mass fraction greater than or equal to 500 ppm, or greater than or equal to 0.10%, or greater than or equal to 0.15%, or greater than or equal to 0.20%, or greater than or equal to 0.30%, or greater than or equal to 0.40%.

[0058] Preferably, the mass fraction of Ni is less than or equal to 3.00%, or 2.90%, or 2.80%, or 2.70%, or 2.60%, or 2.50%, or 2.40%, or 2.30%, or 2.20%, or 2.10%, or 2.00%, or 1.90%, or 1.80%, or 1.70%, or 1.60%, or 1.50%, or 1.40%, or 1.30%, or 1.20%, or 1.10%, or 1.00%, or 0.90%, or 0.80%, or 0.70%, or 0.60, or 0.50%.

[0059] This element can make it possible to increase the mechanical strength of the alloy by solid solution and / or by dispersoids which can form during the manufacture of the part or during post-manufacturing heat treatments. This element has low solubility in aluminum. The addition of this element can make it possible to harden the alloy without having a significant impact on the conductivity. Cu and / or Ag:

[0060] According to the present invention, at least one alloying element selected from: Cu and Ag may be present in the aluminum alloy in a mass fraction of 0.05 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.50%, preferably 0.10 to 1.40%, preferably 0.10 to 1.30%, preferably 0.10 to 1.20%, preferably 0.10 to 1.10%, preferably 0.10 to 1.00%, preferably 0.10 to 0.90%, preferably 0.10 to 0.80%, preferably 0.10 to 0.70% each and / or in total.

[0061] Preferably, the mass fraction of at least one alloying element chosen from: Cu and Ag is greater than or equal to 0.05%, or 0.06%, or 0.07%, or 0.08%, or 0.09%, or 0.10% each and / or in total. Preferably, the mass fraction of at least one alloying element chosen from: Cu and Ag is less than or equal to 3.00%, or 2.90%, or 2.80%, or 2.70%, or 2.60%, or 2.50%, or 2.40%, or 2.30%, or 2.20%, or 2.10%, or 2.00%, or 1.90%, or 1.80%, or 1.70%, or 1.60%, or 1.50%, or 1.40%, or 1.30%, or 1.20%, or 1.10%, or 1.00%, or 0.90%, or 0.80%, or 0.70% each and / or in total.

[0062] These elements can make it possible to increase the mechanical resistance of the alloy by solid solution and / or by hardening precipitates which can form during the manufacture of the part or during post-manufacturing heat treatments. Zn and / or Li:

[0063] According to the present invention, at least one alloying element chosen from: Zn and Li may be present in the aluminum alloy in a mass fraction less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferentially less than or equal to 0.50%, more preferentially less than or equal to 0.30% each and / or in total. According to a variant, at least one alloying element chosen from: Zn and Li may be present in the aluminum alloy in a mass fraction greater than or equal to 500 ppm, or greater than or equal to 0.10%, or greater than or equal to 0.20% each and / or in total.

[0064] Preferably, the mass fraction of at least one alloying element chosen from: Zn and Li is less than 2.00%, or less than or equal to 1.90%, or 1.80%, or 1.70%, or 1.60%, or 1.50%, or 1.40%, or 1.30%, or 1.20%, or 1.10%, or 1.00%, or 0.90%, or 0.80%, or 0.70%, or 0.60%, or 0.50%, or 0.40%, or 0.30% each and / or in total. Preferably, the mass fraction of at least one alloying element chosen from: Zn and Li is greater than or equal to 500 ppm, or 0.06%, or 0.07%, or 0.08%, or 0.09%, or 0.10%, or 0.11%, or 0.12%, or 0.13%, or 0.14%, or 0.15%, or 0.16%, or 0.17%, or 0.18%, or 0.19%, or 0.20% each and / or in total.

[0065] These elements can make it possible to increase the mechanical strength of the alloy by solid solution. However, these elements are sensitive to evaporation during laser melting, which can lead to the formation of fumes and instabilities of the melt pools. The excessive addition of these elements can significantly lower the electrical conductivity. Thus, according to one embodiment, the addition of these elements is preferably to be avoided.

[0066] Co, La, Ce, mischmetal, W, Ta, Mo, Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and / or Sn:

[0067] According to the present invention at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo, Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, may be present in the aluminum alloy in a mass fraction less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferentially less than or equal to 0.50%, more preferentially less than or equal to 0.30%, even more preferentially less than or equal to 0.10% each, and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30% in total.According to a variant, at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn may be present in the aluminum alloy in a mass fraction greater than 100 ppm, or greater than 300 ppm, or greater than 500 ppm each and / or in total.

[0068] Preferably, the mass fraction of at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn is less than or equal to 2.00%, or 1.90%, or 1.80%, or 1.70%, or 1.60 %, or 1.50%, or 1.40%, or 1.30%, or 1.20%, or 1.10%, or 1.00%, or 0.90%, or 0.80%, or 0.70%, or 0.60, or 0.50%, or 0.40%, or 0.30% each and / or in total, or less than or equal to 0.20% or 0.10% each. Preferably, the mass fraction of at least one alloying element selected from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn is greater than or equal to 100 ppm, or 200 ppm or 300 ppm or 400 ppm or 500 ppm each and / or in total.

[0069] These elements can make it possible to increase the mechanical resistance of the alloy by solid solution and / or by dispersoids or precipitates which can form during the manufacture of the part or during post-manufacturing heat treatments.

[0070] The addition of Ca may be of interest, particularly to limit the evaporation of Mg and to limit its oxidation on the surface of the liquid bath during the atomization step and during the laser fusion step on the powder bed.

[0071] The method may include, following the formation of the layers, i.e. following the formation of the final part, an application of at least one heat treatment. This treatment is also called post-manufacturing heat treatment or post-treatment. The post-manufacturing heat treatment may be or include tempering or annealing. It may also include solution treatment and quenching, although these are preferred. It may also include hot isostatic pressing.

[0072] According to a first variant, in order to favor the mechanical properties, the post-manufacturing heat treatment can be carried out: - at a temperature T' above 400°C, in which case the duration of the post-manufacturing heat treatment is from 0.1 h to 50 h, preferably from 0.1 h to 10 h; - or at a temperature T' between 300°C and 400°C, in which case the duration of the post-manufacturing heat treatment is between 0.1 h and 200 h.

[0073] According to a second variant, in order to favor the thermal or electrical conduction properties, the post-manufacturing heat treatment can be carried out at a temperature T' greater than or equal to 350°C or 400°C for a duration of 0.1 h to 200 h, so as to obtain optimal thermal or electrical conductivity.

[0074] According to another variant, two-stage post-manufacturing heat treatments can make it possible to maximize the electrical conductivity. These treatments consist of first carrying out a first stage at a temperature T' 1 greater than 450°C for a duration of 0.1 h to 100 h, followed by a second stage at a temperature T'2 between 300°C and 450°C for a duration of 0.1 h to 200 h.

[0075] According to another variant, two-stage post-manufacturing heat treatments can make it possible to maximize the electrical conductivity and / or the hardness. These treatments consist of first carrying out a first stage at a temperature T' 1 lower than 380°C for a duration of 0.1 h to 200 h, followed by a second stage at a temperature T'2 between 380°C and 450°C for a duration of 0.1 h to 200 h.

[0076] According to another variant, three-stage post-manufacturing heat treatments can make it possible to maximize the electrical conductivity and / or the hardness. These treatments consist of first carrying out a first stage at a temperature T' 1 of between 250°C and 450°C for a duration of 0.1 h to 200 h, followed by a second stage at a temperature T'2 greater than 450°C for a duration of 0.1 h to 100 h, followed by a third stage at a temperature T'3 of between 250°C and 450°C for a duration of 0.1 h to 200 h.

[0077] Multi-level treatments with a number of levels greater than 3 can also be considered.

[0078] According to one embodiment, the method may comprise hot isostatic pressing (HIP). The HIP treatment may in particular make it possible to improve the elongation properties and the fatigue properties. The hot isostatic pressing may be carried out before, after or instead of the post-manufacturing heat treatment. Advantageously, the hot isostatic pressing is carried out at a temperature of 250°C to 500°C and preferably of 300°C to 450°C, at a pressure of 500 to 3000 bars and for a duration of 0.5 to 100 hours.

[0079] According to an advantageous embodiment, the method does not include quenching following the formation of the layers, i.e. following the formation of the final part, or following the post-manufacturing heat treatment. Thus, preferably, the method does not include solution treatment steps followed by quenching.

[0080] The use of post-manufacturing heat treatment, the manufacturing being carried out by an additive manufacturing process, can make it possible to create relaxation conditions allowing the elimination of residual stresses as well as precipitation of hardening phases. This is also referred to as thermal relaxation. The inventors observed that it was preferable for the set temperature T' of the post-manufacturing heat treatment to be between 300°C and 500°C.

[0081] The possible heat treatment and / or hot isostatic compression makes it possible in particular to increase the hardness or the elastic limit and the electrical conductivity of the product obtained. It should however be noted that, generally, the higher the temperature, the more the conductivity (electrical or thermal) is favored to the detriment of mechanical resistance.

[0082] According to one embodiment, in addition to the temperature T' of the post-manufacturing heat treatment, the temperature rise, initiating the post-manufacturing heat treatment, is preferably as rapid as possible. For example, during the temperature rise, the temperature rise rate AT' (usually designated by those skilled in the art as "heating rate" in °C per minute or in °C per second) is preferably greater than 5°C per minute or greater than 10°C per minute, or even preferably greater than 20°C per minute and more advantageously greater than 40°C per minute, and more advantageously greater than 100°C per minute. By temperature rise, we mean the temperature rise to which the part is subjected during the post-manufacturing heat treatment. It seems optimal that the temperature rise is instantaneous, that is to say that the manufactured part is subjected, from the start of the post-manufacturing heat treatment, to the set temperature T' of the post-manufacturing heat treatment. An instantaneous temperature rise can be obtained by placing the manufactured part in a hot furnace, already brought to the set temperature T', or by a rapid heating means such as a fluidized bed or molten salt bath. The temperature rise can also be ensured by induction heating.

[0083] For the same temperature rise outside the part, the temperature variation inside the part depends in particular on the heating medium (liquid or air or inert gas) as well as on the shape of the part. In particular, the temperature in the thickness or at the surface of the part may be different. This is the reason why the temperature rise mentioned above corresponds to the temperature outside the part. The combination of a preheating temperature T, a post-manufacturing heat treatment temperature T' and a temperature rise rate AT', during the temperature rise of the post-manufacturing heat treatment, in the aforementioned ranges of values, makes it possible to obtain parts having good resistance to thermal cracking.

[0084] According to another embodiment, suitable for structurally hardened alloys, solution treatment can be carried out followed by quenching and tempering of the formed part and / or hot isostatic compression. In this case, hot isostatic compression can advantageously replace solution treatment.

[0085] However, the method according to the invention is advantageous, because it preferably does not require solution treatment followed by quenching. Solution treatment can have a detrimental effect on the mechanical strength in certain cases by contributing to a coarsening of the dispersoids or fine intermetallic phases. Preferably, the method according to the present invention does not involve solution treatment and / or quenching following the formation of the layers, i.e. following the formation of the final part, or following the post-manufacturing heat treatment.

[0086] The inventors have introduced a cracking index (FI) defined as the product between the mass fraction of Zr of the alloy in % and the elastic limit at 25°C of the alloy in the as-manufactured state in MPa. Preferably, the method according to the present invention is such that the part 20 has a cracking index less than or equal to 250, preferably less than or equal to 240, preferably less than or equal to 230, preferably less than or equal to 220, preferably less than or equal to 210.

[0087] According to one embodiment, the method according to the present invention comprises in in addition to optionally a machining treatment, and / or a chemical, electrochemical or mechanical surface treatment, and / or a tribofinishing. These treatments can be carried out in particular to reduce roughness and / or improve corrosion resistance and / or improve resistance to the initiation of fatigue cracks.

[0088] Optionally, it is possible to carry out mechanical deformation of the part, for example after additive manufacturing and / or before heat treatment.

[0089] Although described in connection with a powder bed laser fusion type additive manufacturing method, the method can be applied to other additive manufacturing methods of the wire-arc additive manufacturing type (Wire plus Arc Additive Manufacturing), mentioned in connection with the prior art. [Fig. 2] represents such an alternative. An energy source 31, in this case a torch, forms an electric arc 32. In this device, the torch 31 is held by a welding robot 33. The part 20 to be manufactured is arranged on a support 10. In this example, the manufactured part is a wall extending along a transverse axis Z perpendicular to an XY plane defined by the support 10. Under the effect of the electric arc 32, a filler wire 35 melts to form a weld bead. The welding robot is controlled by a digital model M. It is moved so as to form different layers 20i.. .20n, stacked on top of each other, forming the wall 20, each layer corresponding to a weld bead. Each layer 20i.. .20n extends in the XY plane, according to a pattern defined by the digital model M. .

[0090] The diameter of the filler wire is preferably less than 3 mm. It may be from 0.5 mm to 3 mm and is preferably from 0.5 mm to 2 mm, or even from 1 mm to 2 mm. It is for example 1.2 mm.

[0091] Other methods are also conceivable, for example, and in a non-limiting manner: - selective laser sintering; - direct metal laser sintering (Direct Metal Laser Sintering); - selective heat sintering; - electron beam melting; - laser melting deposition; - direct energy deposition; - direct metal deposit (Direct Metal Deposition); - direct laser deposition; - Laser Deposition Technology; - laser net shaping engineering; - laser cladding technology; - Laser Freeform Manufacturing Technology; - laser fusion deposition (Laser Metal Deposition); - cold spray (Cold Spray Consolidation); - additive manufacturing by friction (Additive Friction Stir); - spark plasma sintering or flash sintering (Field Assisted Sintering Technology or spark plasma sintering); or - Inertia Rotary Friction Welding.

[0092] The solutions according to the present invention are particularly suitable for the cold spray process, in particular because of the low hardness of the powder, which facilitates deposition. The part can then be hardened by a hardening anneal (post-heat treatment).

[0093] The solutions according to the present invention are particularly suitable for applications in the electrical, electronic and heat exchanger fields.

[0094] The invention will be explained in more detail in the examples below, which are given for illustrative and non-limiting purposes. Experimental examples Example 1

[0095] A study was conducted on four alloys (A, B, C and D). The compositions, determined by ICP (Inductively Coupled Plasma) in mass %, are shown in Table 1 below. These four alloys were obtained in powder form using gas jet atomization (N2). The particle size was essentially 3 pm to 120 pm, D10 was 23 to 34 pm, D50 was 46 to 62 pm and D90 was 82 to 99 pm.

[0096] [Tables 1] Alloy %Fe %Cr %Zr A 1.10 3.10 1.15 B 2.00 2.00 1.12 C 2.10 3.00 1.15 D 2.10 3.10 0.97

[0097] Using a laser powder bed fusion machine of the EOSM290 type (supplier EOS), cylindrical samples vertical to the construction direction (Z direction) were produced in order to determine the mechanical characteristics of the alloy. These samples had a diameter of 11 mm and a height of 46 mm. When printing these samples, the main laser parameters used were as follows: laser power of 370 W; scanning speed of 1300 mm / s; vector deviation of 0.14 mm; layer thickness of 60 μm. The heating temperature of the manufacturing plate was 100°C. A first part of the samples were kept in the as-manufactured state (without additional post-manufacturing heat treatment). A second part underwent a 1-hour post-manufacturing heat treatment at 400°C with direct firing at 400°C. And a third part underwent a 4-hour post-manufacturing heat treatment at 400°C with direct firing at 400°C.

[0098] The cylindrical samples were machined to obtain tensile specimens with the following characteristics, as described in Table 2 below and [Fig.3].

[0099] [Tables2] Test specimen type 0 (mm) M (mm) LT (mm) R (mm) Le (mm) F (mm) TOR4 4 8 45 3 22 8.7

[0100] In Table 2 above and [Fig.4], 0 represents the diameter of the central part of the test piece; M the width of the two ends of the test piece; LT the total length of the test piece; R the radius of curvature between the central part and the ends of the test piece; Le the length of the central part of the test piece and F the length of the two ends of the test piece.

[0101] A part of the test pieces was tested in tension at room temperature (25°C) according to the standard NF EN ISO 6892-1 (2009-10) and the other part was tested hot (200°C) according to the standard NF EN ISO 6892-2 (2018). The main results obtained are presented in Table 3 below.

[0102] [Tables3] Alloy Heat treatment time at 400°C (h) Tensile test temperature (°C) Rp0.2 (MPa) A 0 25 204 B 0 25 183 C 0 25 215 D 0 25 203 A 1 25 388 B 1 25 371 C 1 25 404 D 1 25 363 A 4 25 396 B 4 25 362 C 4 25 408 D 4 25 385 A 0 200 184 B 0 200 180 C 0 200 214 D 0 200 198 A 1 200 235 B 1 200 228 C 1 200 259 D 1 200 241 B 4 200 200 D 4 200 234

[0103] According to Table 3 above, in the raw state of manufacture (without post-manufacturing heat treatment), all of the alloys tested have an elastic limit at 25°C of less than 220 MPa, which is beneficial for the processability of the alloys by limiting the level of residual stresses during manufacture.

[0104] For the 4 alloys (A, B, C and D), the post-manufacturing heat treatment of 1 h to 400°C allowed a significant increase in Rp0.2 at room temperature compared to the as-manufactured state. This increase in Rp0.2 is 160 MPa for alloy D and it varies between 184 and 189 MPa for alloys A, B and C. This difference in hardening between alloy D and the other 3 alloys shows a positive effect of the Zr content of the alloy on the increase in Rp0.2 at room temperature after heat treatment. Compared to the 1h heat treatment at 400°C, the 4h heat treatment at 400°C shows a slight effect on alloys A, B and C with a difference between +8 and -11 MPa. The effect is more marked for alloy D which gains 22 MPa between the two heat treatments.

[0105] In the raw state of manufacture (without post-manufacturing heat treatment), all of the alloys tested have an elastic limit at 200°C between 180 and 214 MPa.

[0106] For the 4 alloys (A, B, C and D), the post-manufacturing heat treatment of 1 h at 400°C allowed an increase in Rp0.2 at 200°C compared to the as-manufactured state. This increase in Rp0.2 at 200°C varies between 43 and 51 MPa for the 4 alloys A, B and C and D.

[0107] The heat treatment of Ih at 400°C thus seems to have a beneficial effect on the Rp0.2 at 200°C compared to the as-manufactured state. This surprising behavior is different from what has been observed previously on aluminum alloys developed for the laser powder bed fusion process (see for example “Figure 8” of the article S. Griffiths, JR Croteau, MD Rossell, R. Erni, A. De Luca, NQ Vo, DC Dunand, C. Leinenbach, Coarsening- and Creep Resistance of Precipitation-Strengthened Al-Mg-Zr Alloys Processed by Selective Laser Melting, Acta Materialia (2020), doi:https: / / doi.org / 10.1016 / j.actamat.2020.02.008).

[0108] Compared to the 1h heat treatment at 400°C, the 4h heat treatment at 400°C led to a decrease in Rp0.2 at 200°C of 28 MPa for alloy B and only 7 MPa for alloy D.

[0109] The 4-hour treatment at 400°C makes it possible to simulate the effect of very long-term aging for parts in service at 200°C or 250°C, for example. The low drop in Rp0.2 of alloy D is synonymous with excellent thermal stability for this alloy. Example 2

[0110] Using an EOSM290 type laser powder bed fusion machine (EOS supplier), cracking specimens were produced from the 4 alloys (A, B, C and D) in order to study their sensitivity to cracking.

[0111] These specimens, which are shown in [Fig.4], have a particular geometry with two critical sites conducive to crack initiation. When printing these specimens, the main laser parameters used were: laser power of 370 W; scanning speed of 1300 mm / s; vector deviation of 0.14 mm; layer thickness of 60 μm. The EOSM290 machine used allows heating the build plate by heating elements up to a temperature of 200°C. Cracking specimens were printed using this machine with a plate temperature of 100°C. In all cases, the specimens underwent a 2-hour post-manufacturing stress relief treatment at 300°C with a furnace at 25°C and a heating rate of 5°C / min.

[0112] After manufacturing, the test pieces were mechanically polished to 1 pm at the face indicated in [Fig.3] (reference 1). The presence or absence of cracks was checked using an optical microscope with a magnification of X100. The results are summarized in Table 4 below.

[0113] In Table 4, we have also calculated for each alloy a cracking index (FI) defined as the product between the mass fraction of Zr in the alloy in % and the elastic limit at 25°C of the alloy in the as-manufactured state in MPa.

[0114] [T ables 4] Alloy Presence or absence of cracking Cracking index IF A yes 234.6 B no 204.9 C yes 247.2 D no 196.9

[0115] The results in Table 4 show that for the geometry of the cracking parts tested, alloys B and D did not exhibit any cracking. In contrast, alloys A and C exhibited cracks. The proposed cracking index makes it possible to take into account, in the as-manufactured state, the granular structure of the printed part (fraction of fine equiaxed zone) as well as its level of residual stresses. These two parameters (granular structure and level of residual stresses in the as-manufactured state) are considered to be the most impactful on the sensitivity to cracking of the alloys. When the cracking index is greater than or equal to 230, preferably greater than or equal to 240, preferably greater than or equal to 250, even more preferably greater than or equal to 260, the alloy exhibits a high sensitivity to cracking.

[0116] Conversely, when the cracking index is less than or equal to 250, preferably less than or equal to 240, preferably less than or equal to 230, preferably less than or equal to 220, even more preferably less than or equal to 210, the alloy has a low sensitivity to cracking.

Claims

Claims

1. Method for manufacturing a part (20) comprising a formation of successive metal layers (20i...20n), superimposed on each other, each layer being formed by the deposition of a filler metal (15, 35), the filler metal being subjected to an energy input so as to melt and to constitute, by solidifying, said layer, the method being characterized in that the filler metal (15, 35) is an aluminum alloy comprising the following alloying elements (% by weight): - at least one alloying element chosen from: Zr, Hf, Sc and Er, according to a mass fraction of 0.40 to 1.60%, preferably of 0.50 to 1.50%, of preferably from 0.55 to 1.40%, preferably from 0.60 to 1.30%, preferably from 0.60 to 1.25%, preferably from 0.60 to 1.20%, preferably from 0.60 to 1.00%, preferably from 0.60 to 0.95%, preference of 0.65 to 0.90% each and / or in total; - Fe, in a mass fraction of 0.50 to 3.00%, preferably 0.60 to 2.80%, preferably 0.70 to 2.70%, preferably 0.80 to 2.70%, preferably 0.90 to 2.60%, preferably 0.90 to 2.50%, preferably 0.90 to 2.40%, preferably 0.90 to 2.30%, preferably 0.90 to 2.20%; - Cr, according to a mass fraction of 1.00 to 4.00%, preferably 1.50 to 3.80%, preferably 1.60 to 3.70%, preferably 1.70 to 3.60%, preferably 1.75 to 3.50%, preferably 1.75 to 3.40%, preferably 1.75 to 3.30%, preferably 1.75 to 3.20%, preferably 1.80 to 3.20%, preferably 1.90 to 3.20%; - optionally at least one alloying element chosen from: Mn, V and Ti according to a mass fraction greater than or equal to 0.03%, preferably greater than or equal to 0.05%, preferably from 0.10 to 3.00%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.40%, preferably from 0.40 to 2.30%, preferably from 0.40 to 2.20%, preferably from 0.40 to 2.10%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.90%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.70%, preferably from 0.40 to 1.60% each and / or in total; - optionally Mg, according to a mass fraction greater than or equal to 0.03%, preferably from 0.05 to 3.50%, preferably from 0.10 to 3.40%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.30%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.60%; - optionally If, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally Ni, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.05 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.50%, preferably 0.10 to 1.40%, preferably 0.10 to 1.30%, preferably 0.10 to 1.20%, preferably 0.10 to 1.10%, preferably 0.10 to 1.00%, preferably 0.10 to 0.90%, preferably 0.10 to 0.80%, preferably 0.10 to 0.70% each and / or in total; - optionally at least one alloying element chosen from: Zn and Li, according to a mass fraction of less than 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30% each and / or in total; - optionally at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo, Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, according to a mass fraction less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30%, even more preferably less than or equal to 0.10% each, and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30% in total; - impurities: < 0.05% individually, and preferably < 0.15% in total; aluminum remains.

2. Method according to claim 1, characterized in that the aluminum alloy necessarily comprises at least one alloying element chosen from: Mn, V and Ti.

3. A method according to claim 1 or 2, characterized in that the aluminum alloy comprises Mg.

4. A method according to any preceding claim, wherein the mass fraction of aluminum is less than 97%.

5. Method according to any one of the preceding claims, in which the part (20) has a crack index less than or equal to 250, preferably less than or equal to 240, preferably less than or equal to 230, preferably less than or equal to 220, preferably less than or equal to 210, the crack index being defined as the product between the mass fraction of Zr of the alloy in % and the elastic limit at 25°C of the alloy in the as-manufactured state in MPa.

6. Method according to any one of the preceding claims, comprising, following the formation of the layers (20i...20n), i.e. following the formation of the final part, an application of a post-manufacturing heat treatment, preferably tempering or annealing.

7. Method according to any one of the preceding claims, not comprising solution treatment and / or quenching following the formation of the layers, i.e. following the formation of the final part, or following the post-manufacturing heat treatment.

8. Method according to any one of the preceding claims, characterized in that it is carried out at a preheating temperature T of up to 500°C.

9. A method according to any preceding claim, wherein the filler metal takes the form of a powder (15), the exposure of which to a beam of light (12) or charged particles results in localized melting followed by solidification, so as to form a solid layer (20i...20n).

10. A method according to any one of claims 1 to 8, wherein the filler metal is derived from a filler wire (35), the exposure of which to a heat source (32) results in localized melting followed by solidification, so as to form a solid layer (20i.. .20n).

11. Metal part obtained by a process which is the subject of any one of the preceding claims.

12. Powder, intended to be used as a filler material for an additive manufacturing process, characterized in that it is made up of an aluminum alloy, comprising the following alloying elements (% by weight): - at least one alloying element chosen from: Zr, Hf, Sc and Er, according to a mass fraction of 0.40% to 1.60%, preferably 0.50 to 1.50%, preferably 0.55 to 1.40%, preferably 0.60 to 1.30%, preferably 0.60 to 1.25%, preferably 0.60 to 1.20%, preferably 0.60 to 1.00%, preferably 0.60 to 0.95%, preferably 0.65 to 0.90% each and / or in total; - Fe, in a mass fraction of 0.50 to 3.00%, preferably 0.60 to 2.80%, preferably 0.70 to 2.70%, preferably 0.80 to 2.70%, preferably 0.90 to 2.60%, preferably 0.90 to 2.50%, preferably 0.90 to 2.40%, preferably 0.90 to 2.30%, preferably 0.90 to 2.20%; - Cr, according to a mass fraction of 1.00 to 4.00%, preferably 1.50 to 3.80%, preferably 1.60 to 3.70%, preferably 1.70 to 3.60%, preferably 1.75 to 3.50%, preferably 1.75 to 3.40%, preferably 1.75 to 3.30%, preferably 1.75 to 3.20%, preferably 1.80 to 3.20%, preferably 1.90 to 3.20%; - optionally Mg, according to a mass fraction greater than or equal to 0.03%, preferably from 0.05 to 3.50%, preferably from 0.10 to 3.40%, more preferably from 0.20 to 2.50%, even more preferably from 0.30 to 2.30%, even more preferably from 0.40 to 2.00%, even more preferably from 0.40 to 1.80%, even more preferably from 0.40 to 1.60%; - optionally at least one alloying element chosen from: Mn, V and Ti according to a mass fraction greater than or equal to 0.03%, preferably greater than or equal to 0.05%, preferably from 0.10 to 3.00%, preferably from 0.20 to 2.50%, preferably from 0.30 to 2.40%, preferably from 0.40 to 2.30%, preferably from 0.40 to 2.20%, preferably from 0.40 to 2.10%, preferably from 0.40 to 2.00%, preferably from 0.40 to 1.90%, preferably from 0.40 to 1.80%, preferably from 0.40 to 1.70%, preferably from 0.40 to 1.60% each and / or in total; - optionally If, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally Ni, according to a mass fraction less than or equal to 3.00%, preferably less than or equal to 2.50%, preferably less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.05 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.50%, preferably 0.10 to 1.40%, preferably 0.10 to 1.30%, preferably 0.10 to 1.20%, preferably 0.10 to 1.10%, preferably 0.10 to 1.00%, preferably 0.10 to 0.90%, preferably 0.10 to 0.80%, preferably 0.10 to 0.70% each and / or in total; - optionally at least one alloying element chosen from: Zn and Li, according to a mass fraction of less than 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30% each and / or in total; - optionally at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo, Nb, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, according to a mass fraction less than or equal to 2.00%, preferably less than or equal to 1.50%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, more preferably less than or equal to 0.30%, even more preferably less than or equal to 0.10% each, and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30% in total; - impurities: < 0.05% individually, and preferably < 0.15% in total; aluminum remains.

13. Use of a powder according to claim 12, in a manufacturing process chosen from: electron beam melting, cold spraying, laser fusion deposition, friction additive manufacturing, plasma spark sintering and rotary friction welding, preferably cold spraying.

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