Manufacturing process of an aluminum alloy part

Abstract

Method for manufacturing a part (20) comprising a formation of successive metal layers (201…20n), superimposed on each other, each layer being formed by the deposition of a filler metal (15, 25), 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, 25) is an aluminum alloy comprising the following alloying elements (% by weight): - at least one alloying element chosen from: Zr, Hf, and Er, according to a mass fraction greater than or equal to 0.30 each and in total; - at least one alloying element chosen from: Cr, V, Ti and Mn, according to a mass fraction greater than 0.50% each and in total; - optionally Co, La, Ce, mischmetal, W, Ta, Mo, Nb, Fe, Ni, Cu, Ag, Si, Sc, Mg, Zn, Li, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In, Sn and impurities; remains aluminum. Figure 1 FIGURES

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, using 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 designated by the English acronyms LPBF, meaning "Laser Powder Bed Fusion" or "EBM", meaning "Electron Beam Melting".

[0005] 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.

[0006] 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.

[0007] For aluminum alloys, the maximum electrical or thermal conductivity is generally obtained for pure aluminum. However, pure aluminum suffers from poor mechanical properties, which limits its scope of use. To improve the mechanical strength of pure aluminum, it is possible to increase its content of additional elements. Conversely, to improve the electrical conductivity of an aluminum alloy, it is possible to limit the content of additional elements other than aluminum. Thus, the variation in the total content of additional elements impacts in an antinomic manner the conductivity and the mechanical strength of an aluminum alloy. Also, it is difficult to design aluminum alloys having both sufficient thermal conductivity in the as-manufactured state and sufficient mechanical strength after heat treatment.

[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, in particular LPBF, these compositions make it possible to obtain both very good processability of the parts in the LPBF process, and excellent mechanical performance of the parts in service. The good processability of the parts in the LPBF process is obtained by combining, in the as-manufactured state, a sufficiently low level of hardness (for example, Knoop hardness HK0.05 in the as-manufactured state less than 120) and a sufficiently high thermal or electrical conductivity (for example, electrical conductivity in the as-manufactured state greater than 8 MS / m).This combination of hardness and conductivity makes it possible to limit the level of residual stresses in the parts in the as-manufactured state, which significantly limits the risk of cracking, delamination or distortion, thus significantly improving the processability of parts in the LPBF process. The excellent mechanical performance of parts in service is obtained by maximizing the hardness of the parts after post-manufacturing heat treatment (for example, Knoop hardness HK0.05 greater than 114).

[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 (DUGs) 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 for example LPBF. It therefore appears advantageous that the developed solution has less than 97% aluminum, i.e. more than 3% of addition elements in total.

[0010] According to another 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, 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 subject of the invention is a method for 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 method 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, and Er, according to a mass fraction greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferentially from 0.40 to 2.00%, more preferentially from 0.40 to 1.80%, even more preferentially from 0.50 to 1.60%, even more preferentially from 0.60 to 1.50%, even more preferentially from 0.70 to 1.40%, even more preferentially from 0.80 to 1.30% each and in total; - at least one alloying element chosen from: Cr, V, Ti and Mn, in a fraction greater than 0.50%, preferably more than 0.50 to 6.00%, preferably 1.00 to 6.00%, more preferably 1.00 to 5.00%, even more preferably 1.00 to 4.00%, even more preferably 1.00 to 3.00%, each and in total; - optionally at least one alloying element chosen from: Co, La, Ce, mi-schmetal, W, Ta, Mo and Nb, according to a mass fraction of at least 0.10%, preferably at least 0.25%, more preferably at least 0.50% each and in total; and according to a mass fraction of less than 5.00%, preferably less than 4.00%, preferably less than 3.00% each; and according to a mass fraction of less than 7.00%, preferably less than 6.00%, preferably less than 5.00%, preferably less than 4.00% in total; - optionally Fe, according to a mass fraction of 0.10 to 3.00%, preferably 0.15 to 3.00%, preferentially 0.20 to 2.50%, more preferentially 0.30 to 2.50%, even more preferentially 0.50 to 2.50%, even more preferentially initially from 0.75 to 2.25%; - optionally Ni, according to a mass fraction of less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.10 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.00%, preferably 0.10 to 0.70% each and in total; - optionally Si, in a mass fraction of less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; in one embodiment, the Si content is less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Sc, according to a mass fraction of less than 0.80%, preferably less than 0.70%, preferably less than 0.60%, preferably less than 0.50%, preferably less than 0.40%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Mg, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally Zn, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally Li, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally at least one element chosen from: 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 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30%, more preferably less than or equal to 0.10%, even more preferably less than or equal to 700 ppm 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 or second 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 consists of an aluminum alloy, comprising the following alloying elements (% by weight): - at least one alloying element chosen from: Zr, Hf, and Er, according to a mass fraction greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferentially from 0.40 to 2.00%, more preferentially from 0.40 to 1.80%, even more preferentially from 0.50 to 1.60%, even more preferentially from 0.60 to 1.50%, even more preferentially from 0.70 to 1.40%, even more preferentially from 0.80 to 1.30% each and in total; - at least one alloying element chosen from: Cr, V, Ti and Mn, in a fraction greater than 0.50%, preferably more than 0.50 to 6.00%, preferably 1.00 to 6.00%, more preferably 1.00 to 5.00%, even more preferably 1.00 to 4.00%, even more preferably 1.00 to 3.00%, each and in total; - optionally at least one alloying element chosen from: Co, La, Ce, mi-schmetal, W, Ta, Mo and Nb, according to a mass fraction of at least 0.10%, preferably at least 0.25%, more preferably at least 0.50% each and in total; and according to a mass fraction of less than 5.00%, preferably less than 4.00%, preferably less than 3.00% each; and according to a mass fraction of less than 7.00%, preferably less than 6.00%, preferably less than 5.00%, preferably less than 4.00% in total; - optionally Fe, according to a mass fraction of 0.10 to 3.00%, preferably 0.15 to 3.00%, preferentially 0.20 to 2.50%, more preferentially 0.30 to 2.50%, even more preferentially 0.50 to 2.50%, even more preferentially 0.75 to 2.25%; - optionally Ni, according to a mass fraction of less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.10 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.00%, preferably 0.10 to 0.70% each and in total; - optionally Si, in a mass fraction of less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; in one embodiment, the Si content is less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Sc, according to a mass fraction of less than 0.80%, preferably less than 0.70%, preferably less than 0.60%, preferably less than 0.50%, preferably less than 0.40%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Mg, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally Zn, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally Li, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally at least one element chosen from: 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 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30%, more preferably less than or equal to 0.10%, even more preferably less than or equal to 700 ppm 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: EBM (electron beam melting), cold spraying (CSC or CS), laser fusion deposition (LMD), friction additive manufacturing (AFS, or AFSD, or FSAM, or FS), plasma spark sintering (FAST) or rotary friction welding (IRFW), preferably cold spraying (CSC).

[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.l] [Fig.l] is a diagram illustrating an LPBF type additive manufacturing process.

[0022] [Fig.2] [Fig.2] is a diagram illustrating an additive manufacturing process of the type WAAM.

[0023] [Fig.3] [Fig.3] is a diagram of the wafer after laser reflow used according to the examples.

[0024] [Fig.4] [Fig.4] is a schematic of the Knoop hardness measurement test. PRESENTATION OF SPECIAL EMBODIMENTS

[0025] In the description, unless otherwise indicated: - the designation of aluminum alloys is in accordance with the nomenclature of The Aluminum Association; - the contents of chemical elements 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%.

[0026] By impurities we mean chemical elements present in the alloy unintentionally.

[0027] [Fig.l] shows schematically the operation of an additive manufacturing process of the selective laser melting type (Laser Powder Bed Fusion or LPBF). 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 melting 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 may 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.

[0028] 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 the manufacture of the part 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.

[0029] For aluminum alloys, the support 10 or platen can be heated to a preheating temperature T of up to 500°C. Machines currently available on the market generally offer heating of the platen up to 200°C. The heating temperature of the platen (= preheating temperature T) can be for example approximately 50°C, 100°C, 150°C, 200°C, 250°C, 300°C or 350°C or 400°C or 450°C or 500°C. Heating the platen generally makes it possible to reduce the humidity in the powder bed and also to reduce the 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 heating the plate 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, making it possible to carry out this preheating step, can be used within the framework of the present invention to heat and control the temperature, for example an infrared lamp. Thus, the method according to the present invention can be carried out at . a preheating temperature T of up to 500°C.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The implementation of such a process allows the manufacture of parts with a high yield, which can reach or even exceed 200 cmVh per laser.

[0034] 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.

[0035] 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.

[0036] The following elements can be used in the aluminum alloy. Zr, Hf and / or Er:

[0037] According to the present invention, at least one alloying element chosen from: Zr, Hf and Er is present in the aluminum alloy in a mass fraction greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferentially from 0.40 to 2.00%, more preferentially from 0.40 to 1.80%, even more preferentially from 0.50 to 1.60%, even more preferentially from 0.60 to 1.50%, even more preferentially from 0.70 to 1.40%, even more preferentially from 0.80 to 1.30% each and in total. Preferably, the mass fraction of at least one alloying element chosen from: Zr, Hf and Er is greater than or equal to 0.30%, or 0.35%, or 0.40%, or 0.45%, or 0.50%, or 0.55%, or 0.60%, or 0.65%, or 0.70% each and in total.Preferably, the mass fraction of at least one alloying element chosen from: Zr, Hf and Er is less than or equal to 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% each and in total.

[0038] These elements have a high solubility in the raw state of manufacture. Their addition can thus significantly lower the conductivity in the raw state. However, the addition of a post-manufacturing 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 Er). The formation of these dispersoids during the heat treatment can simultaneously increase the hardness and the electrical conductivity compared to the raw state.

[0039] These elements can also make it possible to control the granular structure during laser melting by promoting the appearance of equiaxed grains.

[0040] Furthermore, the presence of at least one alloying element chosen from: Zr, Hf and Er in the alloy can confer good processability of 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 cracking, and low porosity. Cr, V, Ti and / or Mn:

[0041] According to the present invention, at least one alloying element chosen from: Cr, V, Ti and Mn is present in the aluminum alloy in a mass fraction greater than 0.50%, preferably more than 0.50 to 6.00%, preferably 1.00 to 6.00%, more preferably 1.00 to 5.00%, even more preferably 1.00 to 4.00%, even more preferably 1.00 to 3.00%, each and in total. Preferably, the mass fraction of at least one alloying element chosen from: Cr, V, Ti and Mn is greater than 0.50%, or greater than or equal to 0.60%, or 0.70%, or 0.80%, or 0.90%, or 1.00% each and in total. Preferably, the mass fraction of at least one alloying element chosen from: Cr, V, Ti and Mn is less than or equal to 6.00%, or 5.50%, or 5.00%, or 4.50%, or 4.00%, or 3.50%, or 3.00% each and in total.

[0042] These elements 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. But these elements have a high solubility in aluminum and have a negative impact on the conductivity. The addition of these elements is of interest for alloys targeting certain applications which do not require particular performances in terms of electrical or thermal conductivity but which require high mechanical strength, such as structural parts, hydraulic blocks, etc. Co, La, Ce, mischmetal, W, Ta, Mo and / or Nb:

[0043] According to the present invention, at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and / or Nb may be present in the aluminum alloy in a mass fraction of at least 0.10%, preferably at least 0.25%, more preferably at least 0.50% each and in total; and in a mass fraction of less than 5.00%, preferably less than 4.00%, preferably less than 3.00% each; and in a mass fraction of less than 7.00%, preferably less than 6.00%, preferably less than 5.00%, preferably less than 4.00% in total. Preferably, the mass fraction of at least one alloying element selected from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb is greater than or equal to 0.10%, or 0.15%, or 0.20%, or 0.25%, or 0.30%, or 0.35%, or 0.40%, or 0.45%, or 0.50% each and in total. Preferably, the mass fraction of at least one alloying element selected from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb is less than 5.00%, or 4.50%, or 4.00%, or 3.50%, or 3.00% each.Preferably, the mass fraction of at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb is less than 7.00%, or 6.50%, or 6.00%, or 5.50%, or 5.00%, or 4.50%, or 4.00% in total.

[0044] These elements 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. These elements have low solubility in aluminum. The addition of these elements can harden the alloy without having a significant negative impact on the conductivity.

[0045] Preferably, the aluminum alloy comprises at least one alloying element chosen from Co, La, Ce, mischmetal, W, Ta, Mo and Nb. Fe:

[0046] According to the present invention, the element Fe may be present in the aluminum alloy in a mass fraction of 0.10 to 3.00%, preferably 0.15 to 3.00%, preferentially 0.20 to 3.00%, more preferentially 0.20 to 2.50%, even more preferentially 0.30 to 2.50%, even more preferentially 0.50 to 2.50%, even more preferentially 0.75 to 2.25%. Preferably, the mass fraction of Fe is greater than or equal to 0.10%, or 0.15%, or 0.20%, or 0.25%, or 0.30%, or 0.35%, or 0.40%, or 0.45%, or 0.50%, or 0.55%, or 0.60%, or 0.65%, or 0.70%, or 0.75%. Preferably, the mass fraction of Fe 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 2.25%.

[0047] 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 can harden the alloy without having a significant negative impact on the conductivity.

[0048] Preferably, the aluminum alloy comprises Fe. Neither:

[0049] According to the present invention, the element Ni may be present in the aluminum alloy in a mass fraction of less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%.

[0050] 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 can harden the alloy without having a significant impact on the conductivity. Cu and / or Ag:

[0051] According to the present invention, the elements Cu and / or Ag may be present in the aluminum alloy in a mass fraction of 0.10 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.00%, preferably 0.10 to 0.70% each and in total.

[0052] 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. If:

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

[0054] 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. Sc:

[0055] According to the present invention, the element Sc may be present in the aluminum alloy in a mass fraction of less than 0.80%, preferably less than 0.70%, preferably less than 0.60%, preferably less than 0.50%, preferably less than 0.40%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%.

[0056] This element can exhibit the same technical effects as the elements Zr, Hf and Er. On the other hand, according to a variant of the present invention, the inventors have found that a good compromise between the mechanical properties and the conductivity can also be obtained, preferably after heat treatment, by at least partially replacing the group of elements Co, La, Ce, mischmetal, W, Ta, Mo and / or Nb by Sc, according to the mass fractions as described above. Mg, Zn and / or Li:

[0057] According to the present invention, the elements Mg, Zn and / or Li may be present in the aluminum alloy in a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05% each.

[0058] These elements can 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 therefore preferably to be avoided.

[0059] Nd, Y. Tm. Lu. Yb. Sr, Ba. Sb, Bi. Ca, PB In and / or Sn:

[0060] According to the present invention, at least one element chosen from: 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 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30%, more preferably less than or equal to 0.10%, even more preferably less than or equal to 700 ppm 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.

[0061] These elements can make it possible to increase the mechanical resistance 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. However, the excessive addition of these elements can degrade the conductivity of the alloy; for this reason, according to one embodiment, their addition is preferably according to a mass fraction of less than 700 ppm each.

[0062] It should be noted that, preferably, the alloys according to the present invention are not AA6xxx type alloys, due to the absence of simultaneous addition of Si and Mg in quantities greater than 0.2%.

[0063] 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.

[0064] According to a first variant, in order to favor the mechanical properties, the post-manufacturing heat treatment can be performed: - 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.

[0065] 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.

[0066] 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.

[0067] 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 below 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.

[0068] 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 above 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.

[0069] Multi-level treatments with a number of levels greater than 3 can also be considered.

[0070] 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.

[0071] 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 to post-manufacturing heat treatment. Thus, preferably, the process does not include solution treatment steps followed by quenching.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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 manufacturing, within the aforementioned value ranges, allows the production of parts with good resistance to thermal cracking.

[0076] 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 pressing. In this case, hot isostatic pressing can advantageously replace solution treatment.

[0077] 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.

[0078] Preferably, the method according to the present invention is such that the part 20 has: - In the as-manufactured state, an electrical conductivity greater than 8 MS / m; and - In the as-manufactured state, a Knoop hardness HK0.05 less than 140, preferably less than 130, preferably less than 120; and - After a 4-hour post-treatment at 400°C, a Knoop HK0.05 hardness greater than 114.

[0079] According to one embodiment, the method according to the present invention further optionally comprises 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.

[0080] Optionally, it is possible to carry out mechanical deformation of the part, for example after additive manufacturing and / or before heat treatment.

[0081] Although described in connection with an additive manufacturing method of the LPBF type, the method can be applied to other additive manufacturing methods of the WAAM (Wire plus Arc Additive Manufacturing) type, 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 12, 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 plane. XY, according to a pattern defined by the digital model M.

[0082] 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.

[0083] Other methods are also conceivable, for example, and in a non-limiting manner: - selective laser sintering (SLS); - direct metal laser sintering (Direct Metal Laser Sintering or DMLS); - selective heat sintering (SHS); - electron beam melting (EBM); - laser melting deposition; - direct deposit by energy input (Direct Energy Deposition or DED); - direct metal deposition (Direct Metal Deposition or DMD); - direct laser deposition (Direct Laser Deposition or DLD); - Laser Deposition Technology; - laser net shaping engineering; - laser cladding technology; - Laser Freeform Manufacturing Technology (LFMT); - laser fusion deposition (Laser Metal Deposition or LMD); - cold spray (Cold Spray Consolidation or CSC); - additive manufacturing by friction (AFS or AFSD, or FSAM, or FS); - spark plasma sintering or flash sintering (Field Assisted Sintering Technology, FAST or spark plasma sintering); or - Inertia Rotary Friction Welding (IRFW).

[0084] 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 hardening annealing (post-heat treatment).

[0085] The solutions according to the present invention are particularly suitable for applications in the electrical, electronic and heat exchanger fields.

[0086] 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

[0087] The tested alloys were cast into a copper mold using a machine Induthem VC 650V to obtain ingots 130 mm high, 95 mm wide and 5 mm thick.

[0088] The alloys as described in Table 1 below were tested by a rapid prototyping method. Samples were machined for surface scanning with a laser, in the form of wafers with dimensions 60 x 22 x 3 mm, from the ingots obtained above. The wafers were placed in an LPBF machine and surface scans were carried out with a laser following the same scanning strategy and process conditions representative of those used for the LPBF process. It was indeed found that it was possible in this way to evaluate the suitability of the alloys for the LPBF process and in particular, the sensitivity to hot cracking, the hardness in the raw state and after heat treatment, the electrical conductivity in the raw state and after heat treatment.

[0089] Under the laser beam, the metal melts in a bath approximately 500 pm thick. After the laser has passed through, the metal cools rapidly as in the LPBF process. After laser scanning, a thin surface layer approximately 500 pm thick was melted and then solidified. The properties of the metal in this layer are close to the properties of the metal at the core of a part manufactured by LPBF, because the scanning parameters were judiciously chosen. The laser scanning of the surface of the different samples was carried out using a FormUP® 350 selective laser powder bed fusion (LPBF) machine from AddUp. The laser source had a power of 400 W, the vector spacing was 60 pm, the scanning speed was 500 mm / s and the beam diameter was 65 pm.

[0090] On each wafer, two rectangular surfaces of 5 mm x 35 mm each were remelted for hardness measurements and one rectangular surface of 15 mm x 18 mm was remelted for electrical conductivity measurement.

[0091] [Fig. 3] shows an example of a wafer after laser remelting. Reference 1 corresponds to the two rectangular surfaces remelted and used for hardness measurement, reference 2 corresponds to the rectangular surface remelted and used for electrical conductivity measurement and reference 3 corresponds to the non-remelted surface of the initial wafer.

[0092] Following each test, a heat post-treatment was applied to certain samples. The heat treatment was of the annealing type, at a temperature of 400°C, for 1 hour, or 4 hours, or 7 hours. Knoop hardness measurement

[0093] Hardness is an important property for alloys. Indeed, if the hardness in the remelted layer by scanning the surface with a laser is high, a part made with the same alloy will have a high elastic limit.

[0094] To evaluate the hardness of the remelted layer, the plates obtained above were cut in the plane perpendicular to the direction of the laser passes and were then polished. After polishing, hardness measurements were carried out in the remelted layer. The hardness measurement was carried out with a Struers Durascan model device. The 50 g Knoop hardness method with the long diagonal of the indentation placed parallel to the plane of the remelted layer was chosen to keep sufficient distance between the indentation and the edge of the sample. 30 indentations were positioned at the mid-thickness of the remelted layer. [Fig.4] shows an example of the hardness measurement. Reference 4 corresponds to the remelted layer, reference 5 corresponds to a Knoop hardness indentation and reference 6 corresponds to the non-remelted area.

[0095] The hardness was measured according to the Knoop scale with a load of 50 g after laser treatment (in the raw state) and after an additional heat treatment at 400°C for variable durations, allowing in particular to evaluate the suitability of the alloy for hardening during a heat treatment and the effect of a possible CIC treatment on the mechanical properties and the electrical conductivity. Electrical conductivity measurement

[0096] The 15 mm x 18 mm rectangular remelted surface of each wafer was subjected to electrical conductivity measurements, based on the fact that electrical conductivity evolves in a similar way to thermal conductivity. A linear dependence relationship between thermal conductivity and electrical conductivity, according to the Wiedemann Franz law, was validated in the Hatch publication "Aluminium properties and physical metallurgy" ASM Metals Park, OH, 1988. Electrical conductivity measurements were made at the center of the remelted surface in the plane of the large face of the wafers (plane parallel to the direction of the laser passes). Conductivity measurements were made in the as-cast state (without post-manufacturing heat treatment) and after heat treatment at 400°C for varying durations of 1 hour, 4 hours or 7 hours. An average of 5 different measurements was made for each condition.

[0097] The conductivity measurements were carried out at a temperature of approximately 20°C using a Foerster Sigmatest 2.069 measuring device at a frequency of 960 kHz. The choice of this frequency makes it possible to restrict the measurement depth of the electrical conductivity to the level of the remelted area of the wafer.

[0098] The composition of the aluminum alloys tested is presented in Table 1 below, in mass percentages.

[0099] A reference alloy was used: composition No. 1, which contains aluminum, as well as the following alloying elements: Fe (1.00%) and Zr (1.20%). Composition No. Type Fe Zr Mischmeta 1 Cr Ti Mn V 1 Reference 1.00 1.20 2 Invention 1.00 1.20 2.50 2.00 3 Invention 1.00 1.20 2.50 3.00 4 Invention 2.00 1.20 2.50 3.00 5 Invention 2.00 1.20 2.50 1.00 6 Invention 1.00 1.20 1.00 7 Invention 2.00 1.20 2.00 8 Invention 1.00 1.20 2.50 1.00 9 Invention 1.00 1.20 2.50 2.00 10 Invention 2.00 1.20 2.00 11 Invention 1.00 1.20 2.50 2.00 12 Invention 1.00 1.20 1.00

[0101] Table 2 below shows the Knoop hardness (HK0.05) and electrical conductivity values measured for each alloy, after laser remelting, in the raw state (0 hours of heat treatment). Composition No. Heat treatment at 400°C Knoop hardness (HK0.05) Electrical conductivity (MS / m) 1 Oh 65.36 19.41 2 Oh 94.98 10.98 3 Oh 98.43 11.01 4 Oh 118.94 9.82 5 Oh 90.07 15.30 6 Oh 77.18 12.71 7 Oh 103.47 12.04 8 Oh 79.76 11.22 9 Oh 97.80 8.47 10 Oh 95.29 8.45 11 Oh 94.20 15.42 12 Oh 70.36 11.59

[0103] Table 3 below shows the Knoop hardness (HK0.05) and electrical conductivity values measured for each alloy, after laser remelting, and after annealing at 400°C, carried out after laser remelting, for 1 hour. Composition No. Heat treatment at 400°C Knoop hardness (HK0.05) Electrical conductivity (MS / m) 1 Ih 100.70 25.35 2 Ih 124.94 12.94 3 Ih 128.60 12.67 4 Ih 146.38 11.79 5 Ih 102.78 18.37 6 Ih 104.56 16.19 7 Ih 107.04 14.68 8 Ih 121.21 14.40 9 Ih 128.88 11.56 10 Ih 122.38 12.74 11 Ih 118.18 18.63 12 Ih 106.39 13.23

[0105] Table 4 below shows the Knoop hardness (HK0.05) and electrical conductivity values measured for each alloy, after laser remelting, and after annealing at 400°C, carried out after laser remelting, for 4 hours. Composition No. Heat treatment at 400°C Knoop hardness (HK0.05) Electrical conductivity in (MS / m) 1 4h 113.32 28.64 2 4h 134.79 14.23 3 4h 136.06 13.42 4 4h 149.69 13.01 5 4h 120.26 21.02 6 4h 114.72 17.52 7 4h 121.84 16.31 8 4h 125.53 17.26 9 4h 134.13 14.64 10 4h 128.21 17.18 11 4h 128.12 21.57 12 4h 119.13 14.21

[0107] Table 5 below shows the Knoop hardness (HK0.05) and electrical conductivity values measured for each alloy, after laser remelting, and after annealing at 400°C, carried out after laser remelting, for 7 hours. Composition No. Heat treatment at 400°C Knoop hardness (HK0.05) Electrical conductivity in (MS / m) 1 7h 107.19 29.04 2 7h 134.03 14.46 3 7h 136.31 12.95 4 7h 148.59 12.34 5 7h 119.59 21.29 6 7h 108.82 18.71 7 7h 112.39 17.06 8 7h 121.47 18.50 9 7h 129.38 16.14 10 7h 119.50 18.96 11 7h 125.63 21.05 12 7h 116.71 15.61

[0109] The results in Tables 2, 3, 4 and 5 show that, for all the solutions tested, the conductivity and hardness values were lowest in the raw state. The additional heat treatment carried out at 400°C, made it possible to increase both the electrical conductivity and the Knoop hardness (HK0.05) compared to the raw state.

[0110] For all the solutions tested, the maximum conductivity was obtained after 7 hours at 400°C.

[0111] For all the solutions tested, the maximum hardness was obtained after treatment at 400°C between 1 hour and 7 hours. The time allowing the hardness to be maximized seemed to be between 0.5 hours and 10 hours for all the solutions tested.

[0112] An increase in the duration of the heat treatment at 400°C for durations greater than 10 hours would allow the thermal conductivity to be increased further but would lower the hardness.

[0113] The choice of final heat treatment can thus be chosen according to the intended application.

[0114] For alloys containing Sc, a heat treatment temperature of 300 to 400°C for a duration of 0.5 hours to 10 hours could be optimal to maximize hardness. For example, a temperature of 325°C and a duration of 4 hours.

[0115] Reference alloy No. 1 allowed to obtain the highest electrical conductivity for all the conditions tested: in the raw state (without post-manufacturing heat treatment) and after a heat treatment at 400°C for variable durations of 1 hour, 4 hours or 7 hours. The best Knoop hardness (HK0.05) / electrical conductivity (MS / m) compromise for this alloy was obtained for a post-manufacturing heat treatment of 4 hours at 400°C with respective values of 113.32 HK0.05 for hardness and 28.64 MS / m for conductivity. This alloy offers an excellent candidate for applications requiring high thermal or electrical conductivity such as heat exchangers, heat sinks, electronic boxes, RF antennas, etc.However, the maximum hardness offered by this alloy (113.32 HK0.05) remains insufficient for certain applications which do not require particular performance in terms of electrical conductivity, but which require high mechanical resistance, such as structural parts, hydraulic blocks, etc.

[0116] Tables 4 and 5 show that all the alloys of the invention make it possible to offer, after heat treatment, a Knoop hardness (HK0.05) greater than that of reference alloy No. 1 with a maximum hardness of 149.69 HK0.05 obtained for alloy No. 4 after a post-manufacturing heat treatment of 4 hours at 400°C.

[0117] All of the alloys of the invention can make it possible to obtain both very good processability of the parts in the LPBF process and excellent mechanical performance of the parts in service. The good processability of the parts in the LPBF process can be obtained by combining, in the as-manufactured state, a sufficiently low level of hardness (Knoop hardness HK0.05 in the as-manufactured state less than 120) and a sufficiently high thermal or electrical conductivity (electrical conductivity in the as-manufactured state greater than 8 MS / m). This combination of hardness and conductivity can make it possible to limit the level of residual stresses of the parts in the as-manufactured state, which can significantly limit the risk of cracking, delamination or distortion, thus significantly improving the processability of the parts in the LPBF process.Excellent mechanical performance of parts in service can be achieved by maximizing the hardness of the parts after post-manufacturing heat treatment (Knoop hardness HK0.05 greater than 114 for example after 4 hours of heat treatment at 400°C).

[0118] Table 1 shows that, unlike reference alloy No. 1, all of the alloys of the invention had a total content of addition elements greater than 3%.

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, 25), 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, 25) is an aluminum alloy comprising the following alloying elements (% by weight): - at least one alloying element chosen from: Zr, Hf, and Er, according to a mass fraction greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferentially from 0.40 to 2.00%, more preferentially from 0.40 to 1.80%, even more preferentially from 0.50 to 1.60%, even more preferentially from 0.60 to 1.50%, even more preferentially from 0.70 to 1.40%, even more preferentially from 0.80 to 1.30% each and in total; - at least one alloying element chosen from Cr, V, Ti and Mn, according to a mass fraction greater than 0.50%, preferably more than 0.50 to 6.00%, preferentially from 1.00 to 6.00%, more preferentially from 1.00 to 5.00%, even more preferentially from 1.00 to 4.00%, even more preferentially from 1.00 to 3.00%, each for V, Ti and Mn and in total for Cr, V, Ti and Mn; and according to a mass fraction of more than 0.50 to 3.00%, preferentially from 1.00 to 3.00% for Cr; - Fe, according to a mass fraction of 0.10 to 2.50%, preferably 0.15 to 2.50%, preferentially 0.20 to 2.50%, more preferentially 0.30 to 2.50%, even more preferentially 0.50 to 2.50%, even more preferentially 0.75 to 2.25%; - optionally at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, according to a mass fraction of at least 0.10%, preferably at least 0.25%, more preferably at least 0.50% each and in total; and according to a mass fraction of less than 5.00%, preferably less than 4.00%, preferably less than 3.00% each; and according to a mass fraction of less than 7.00%, preferably less than 6.00%, preferably less than 5.00%, preferably less than 4.00% in total; - optionally Ni, according to a mass fraction of less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.10 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.00%, preferably 0.10 to 0.70% each and in total; - optionally If, according to a mass fraction less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Sc, according to a mass fraction of less than 0.80%, preferably less than 0.70%, preferably less than 0.60%, preferably less than 0.50%, preferably less than 0.40%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Mg, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferably less than 0.50%, more preferably less than 0.30%, even more preferably less than 0.10%, even more preferably less than 0.05%; - optionally Zn, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally Li, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally at least one element chosen from: 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 1.00%, preferably less than or equal to 0.50%, preferably less than or equal to 0.30%, more preferably less than or equal to 0.10%, even more preferably less than or equal to 700 ppm 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%; remains aluminum.

2. Method according to claim 1, characterized in that the aluminum alloy comprises at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb.

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

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: - In the as-manufactured state, an electrical conductivity greater than 8 MS / m; and - In the as-manufactured state, a Knoop hardness HK0.05 less than 140, preferably less than 130, preferably less than 120; and - After a post-treatment of 4 hours at 400°C, a Knoop hardness HK0.05 greater than 114.

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 (25), the exposure of which to a heat source (22) 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 in an additive manufacturing process, characterized in that it consists of an aluminum alloy, comprising the following alloying elements (% by weight): - at least one alloying element chosen from: Zr, Hf, and Er, according to a mass fraction greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferentially from 0.40 to 2.00%, more preferentially from 0.40 to 1.80%, even more preferentially from 0.50 to 1.60%, even more preferentially from 0.60 to 1.50%, even more preferentially from 0.70 to 1.40%, even more preferentially from 0.80 to 1.30% each and in total; - at least one alloying element chosen from Cr, V, Ti and Mn, according to a mass fraction greater than 0.50%, preferably more than 0.50 to 6.00%, preferentially from 1.00 to 6.00%, more preferentially from 1.00 to 5.00%, even more preferentially from 1.00 to 4.00%, even more preferentially from 1.00 to 3.00%, each for V, Ti and Mn and in total for Cr, V, Ti and Mn; and according to a mass fraction of more than 0.50 to 3.00%, preferentially from 1.00 to 3.00% for Cr; - Fe, according to a mass fraction of 0.10 to 2.50%, preferably 0.15 to 2.50%, preferentially 0.20 to 2.50%, more preferentially 0.30 to 2.50%, even more preferentially 0.50 to 2.50%, even more preferentially 0.75 to 2.25%; - optionally at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, according to a mass fraction of at least 0.10%, preferably at least 0.25%, more preferably at least 0.50% each and in total; and according to a mass fraction of less than 5.00%, preferably less than 4.00%, preferably less than 3.00% each; and according to a mass fraction of less than 7.00%, preferably less than 6.00%, preferably less than 5.00%, preferably less than 4.00% in total; - optionally Ni, according to a mass fraction of less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally at least one alloying element chosen from: Cu and Ag, according to a mass fraction of 0.10 to 3.00%, preferably 0.10 to 2.00%, preferably 0.10 to 1.60%, preferably 0.10 to 1.00%, preferably 0.10 to 0.70% each and in total; - optionally If, according to a mass fraction less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Sc, according to a mass fraction of less than 0.80%, preferably less than 0.70%, preferably less than 0.60%, preferably less than 0.50%, preferably less than 0.40%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally Mg, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally Zn, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally Li, according to a mass fraction of less than 2.00%, preferably less than 1.00%, preferentially less than 0.50%, more preferentially less than 0.30%, even more preferentially less than 0.10%, even more preferentially less than 0.05%; - optionally at least one element chosen from: 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 1.00%, preferably less than or equal to 0.50%, preferentially less than or equal to 0.30%, more preferentially less than or equal to 0.10%, even more preferentially less than or equal to 700 ppm 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.

13. Use of a powder according to claim 12, in a manufacturing process chosen from: EBM (electron beam melting), cold spraying (CSC or CS), laser fusion deposition (LMD), friction additive manufacturing (AFS or AFSD, or FSAM, or FS), plasma spark sintering (FAST) or rotary friction welding (IRFW), preferably cold spray (CSP).

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