Process for manufacturing an aluminium alloy part

Abstract

The invention relates to a process for manufacturing a part (20) comprising a formation of successive metal layers (201 ... 20n) that are stacked on one another, each layer being formed by depositing a filler metal (15, 25), energy being supplied to the filler metal in such a way that the filler metal melts and, upon solidification, constitutes said layer, the process being characterised in that the filler metal (15, 25) is an aluminum alloy comprising the following alloying elements (in wt.%): - at least one alloying element chosen from among: Zr, Hf and Er, in a weight fraction of greater than or equal to 0.30 each and in total; - at least one alloying element chosen from among: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, in a weight fraction of at least 0.10 each and in total; and in a weight fraction of less than 5.00% each; and in a weight fraction of less than 7.00% in total; - optionally Fe, Ni, Si, Cu, Ag, Sc, Cr, V, Ti, Mn, Mg, Zn, Li, Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In, Sn and impurities; the remainder being aluminium.

Description

[0001] DESCRIPTION

[0002] Title: Manufacturing process of an aluminum alloy part

[0003] The technical field of the invention is a method of manufacturing an aluminum alloy part, using an additive manufacturing technique.

[0004] PREVIOUS ART

[0005] Since the 1980s, additive manufacturing techniques have been developing. They involve shaping a part by adding material, which is the opposite of machining techniques, which aim to remove material. Once limited to prototyping, additive manufacturing is now operational for mass-producing industrial products, including metal parts.

[0006] 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 was described in document W02015006447. 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. Regardless of the additive manufacturing method applied, the thickness of each added layer is of the order of a few tens or hundreds of microns.

[0007] Other additive manufacturing methods can be used. For example, but not limited to, 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 such as an electron beam or laser beam, the method also being designated by the English acronyms LPBF, meaning "Laser Powder Bed Fusion" or "EBM", meaning "Electron Beam Melting".

[0008] 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. 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. In addition, the parts used have interesting thermal conductivity or electrical conductivity properties. This good compromise between mechanical performance and thermal conductivity makes it possible to diversify the application possibilities of these parts.

[0009] For aluminum alloys, 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 the conductivity and mechanical strength of an aluminum alloy in an antinomic way. Therefore, it is difficult to design aluminum alloys with a good compromise between mechanical strength and electrical conductivity.

[0010] 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 containing more than 97% aluminum intended for the additive manufacturing process, such as LPBF. It therefore appears advantageous for the developed solution to have less than 97% aluminum, i.e., more than 3% of additive elements in total. This condition makes the alloy design exercise even more difficult, especially if the aim is to maintain a minimum acceptable electrical conductivity of around 25 MS / m (which corresponds to the reference conductivity value of alloy 6061 in the T6 metallurgical state).

[0011] 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 comprising more than 3% of addition elements in total and having an electrical conductivity after post-manufacturing heat treatment greater than 25 MS / m. 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 making it possible, after post-manufacturing heat treatment, to maximize the hardness (Knoop hardness HK0.05 greater than 105) while retaining an electrical conductivity greater than 25 MS / m.

[0012] STATEMENT OF THE INVENTION

[0013] A first subject 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 method being characterized in that the filler metal is an aluminum alloy comprising the following alloying elements in mass percentages:

[0014] - 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;

[0015] - 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;

[0016] - optionally Fe, 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%;

[0017] - 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%;

[0018] - 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;

[0019] - 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%;

[0020] - 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%;

[0021] - optionally at least one alloying element chosen from Cr, V, Ti and Mn, in a fraction of less than 0.50%, preferably less than 0.30%, preferentially less than 0.20%, preferentially less than 0.10%, more preferentially less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferentially less than 0.50%, more preferentially less than 0.10%, even more preferentially less than 0.05% in total;

[0022] - 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%;

[0023] - 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%;

[0024] - 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%;

[0025] - 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;

[0026] - impurities: < 0.05% individually, and preferably < 0.15% in total; remainder aluminum.

[0027] A second subject 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 method being characterized in that the filler metal is an aluminum alloy comprising the following alloying elements in mass percentages:

[0028] - 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;

[0029] - 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%;

[0030] - 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;

[0031] - optionally Fe, 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%;

[0032] - 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%;

[0033] - 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;

[0034] - 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%;

[0035] - optionally at least one alloying element chosen from Cr, V, Ti and Mn, in a fraction of less than 0.50%, preferably less than 0.30%, preferentially less than 0.20%, preferentially less than 0.10%, more preferentially less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferentially less than 0.50%, more preferentially less than 0.10%, even more preferentially less than 0.05% in total;

[0036] - 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%;

[0037] - 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%;

[0038] - 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%;

[0039] - 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;

[0040] - impurities: < 0.05% individually, and preferably < 0.15% in total; remainder aluminum.

[0041] Each layer can describe a pattern defined from a digital model. The pattern of each layer is a two-dimensional shape, which corresponds to a cross-section of the final object to be obtained in three dimensions.

[0042] 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 is derived 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.

[0043] A third subject of the invention is a metal part, obtained by a method according to the first or second subject of the invention. A fourth 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):

[0044] - 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;

[0045] - 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;

[0046] - optionally Fe, 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%;

[0047] - 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%;

[0048] - 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;

[0049] - 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%;

[0050] - 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%;

[0051] - optionally at least one alloying element chosen from Cr, V, Ti and Mn, according to a mass fraction of less than 0.50%, preferably less than 0.30%, preferentially less than 0.20%, preferentially less than 0.10%, more preferentially less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferentially less than 0.50%, more preferentially less than 0.10%, even more preferentially less than 0.05% in total;

[0052] - 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%;

[0053] - 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%;

[0054] - 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%;

[0055] - 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;

[0056] - impurities: < 0.05% individually, and in total < 0.15%; remainder aluminum.

[0057] A fifth 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):

[0058] - 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;

[0059] - 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%;

[0060] - 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;

[0061] - optionally Fe, 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%;

[0062] - 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%;

[0063] - 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;

[0064] - 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%;

[0065] - optionally at least one alloying element chosen from Cr, V, Ti and Mn, according to a mass fraction of less than 0.50%, preferably less than 0.30%, preferentially less than 0.20%, preferentially less than 0.10%, more preferentially less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferentially less than 0.50%, more preferentially less than 0.10%, even more preferentially less than 0.05% in total;

[0066] - 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%;

[0067] - 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%;

[0068] - 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;

[0069] - impurities: < 0.05% individually, and in total < 0.15%; remainder aluminum.

[0070] The aluminum alloy forming the filler material may have the characteristics described in connection with the first subject of the invention.

[0071] 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.

[0072] 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.

[0073] A sixth 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).

[0074] 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

[0075] [Fig. 1] Figure 1 is a schematic diagram illustrating an LPBF additive manufacturing process. [Fig. 2] Figure 2 is a schematic diagram illustrating a WAAM additive manufacturing process. [Fig. 3] Figure 3 is a schematic diagram of the wafer after laser reflow used according to the examples. [Fig. 4] Figure 4 is a schematic diagram of the Knoop hardness measurement test.

[0076] PRESENTATION OF SPECIAL EMBODIMENTS

[0077] In the description, unless otherwise indicated:

[0078] - the designation of aluminum alloys is in accordance with the nomenclature of The Aluminum Association;

[0079] - 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%.

[0080] Impurity means chemical elements present in the alloy unintentionally.

[0081] Figure 1 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 numerical 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 numerical model. 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...20 n. 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 fused and solidified 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.

[0082] An increase in layer thickness can be beneficial to increase productivity during printing and to limit sensitivity to thermal cracking related to residual stresses during part manufacturing and / or during post-manufacturing heat treatment. An increase in layer thickness can 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 can be for example from 60 to 250 pm, preferably from 80 to 200 pm, preferably from 90 to 180 pm, preferably from 100 to 180 pm, preferably from 110 to 170 pm, preferably from 120 to 160 pm.

[0083] 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 platen heating up to 200°C. The platen heating temperature (= 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 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 would seem 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 scope 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.

[0084] 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.

[0085] Alternatively, the preheating temperature T corresponds to the conditions under which effective stress relief can be achieved. The preheating temperature range T may 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 stress relief heat treatment, as described below in this description, is also relevant.

[0086] The powder may have at least one of the following characteristics:

[0087] - 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.

[0088] - Spherical shape. The sphericity of a powder can, for example, be determined using a morphogranulometer.

[0089] - 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 seconds.

[0090] - Low porosity, preferably 0 to 5%, more preferably 0 to 2%, even more preferably 0 to 1%, more preferably 0 to 0.5% by volume. Porosity can be determined, in particular, by image analysis from optical micrographs or by helium pycnometry (see ASTM B923).

[0091] - 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.

[0092] The implementation of such a process allows the production of parts with a high yield, which can reach or even exceed 200 cm 3 / h per laser.

[0093] Furthermore, the applicant observed that the application of post-manufacturing heat treatments such as quenching could cause distortion of the part, due to the sudden temperature variation. 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 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.

[0094] Having noted the above, the applicant sought an alloy composition, forming the filler material, making it possible to obtain acceptable mechanical and conductivity properties, without requiring the application of heat treatments, subsequent to the formation of the layers, i.e. 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 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.

[0095] The following elements can be used in aluminum alloy.

[0096] Zr, Hf and / or Er:

[0097] According to the present invention, the elements Zr, Hf and / or Er are 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. According to a variant, the mass fraction of the elements Zr, Hf and / or Er may be greater than or equal to 0.30%, or 0.40%, or 0.50%, or 0.60%, or 0.70%, or 0.80%. According to a variant, the mass fraction of the elements Zr, Hf and / or Er may be 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%.

[0098] 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-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 the AI3X type (X = Zr or Hf or Er). The formation of these dispersoids during the heat treatment can simultaneously increase the hardness and electrical conductivity compared to the as-manufactured state.

[0099] These elements can also help control the granular structure during laser fusion by promoting the appearance of equiaxed grains.

[0100] Furthermore, the presence of Zr, Hf and / or 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 quasi-absence of defects, such as cracking, and low porosity. Co, La, Ce, mischmetal, W, Ta, Mo and / or Nb:

[0101] According to the present invention, the elements 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.

[0102] These elements can increase the mechanical strength of the alloy through solid solution and / or dispersoids that may form during part manufacturing or post-manufacturing heat treatments. These elements have low solubility in aluminum. Adding these elements can harden the alloy without significantly negatively impacting conductivity.

[0103] Fe:

[0104] According to the present invention, the element Fe 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%. Alternatively, the element Fe may be present in the aluminum alloy in a mass fraction of greater than 500 ppm, or greater than 0.10%, or greater than 0.15%, or greater than 0.20%, or greater than 0.30%, or greater than 0.40%.

[0105] This element can be used to increase the mechanical strength of the alloy by solid solution and / or by dispersoids that can form during the manufacturing of the part or during post-manufacturing heat treatments. This element has low solubility in aluminum. The addition of this element can help harden the alloy without having a significant negative impact on conductivity.

[0106] Neither :

[0107] 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%. According to a variant, the element Ni may be present in the aluminum alloy in a mass fraction greater than 500 ppm, or greater than 0.10%, or greater than 0.15%, or greater than 0.20%, or greater than 0.30%, or greater than 0.40%. This element may make it possible to increase the mechanical strength of the alloy by solid solution and / or by dispersoids which may 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 may make it possible to harden the alloy without having a significant impact on the conductivity.

[0108] Cu and / or Ag:

[0109] 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.

[0110] These elements can 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.

[0111] SH

[0112] 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%. Alternatively, the element Si may be present in the aluminum alloy in a mass fraction of greater than 500 ppm, or greater than 0.10%, or greater than 0.15%.

[0113] 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.

[0114] Sc:

[0115] 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%; and preferably in a mass fraction of greater than 500 ppm, preferably greater than 0.10%, preferably greater than 0.15%, preferably greater than 0.20%.

[0116] 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.

[0117] Cr, V, Ti and / or Mn:

[0118] According to the present invention, the elements Cr, V, Ti and / or Mn may be present in the aluminum alloy in a mass fraction of less than 0.50%, preferably less than 0.30%, preferentially less than 0.20% each, and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferentially less than 0.50% in total. According to a variant, the elements Cr, V, Ti and / or Mn may be present in the aluminum alloy in a mass fraction of greater than 300 ppm, or greater than 500 ppm, or greater than 0.10% each and in total.

[0119] 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. However, these elements have a high solubility in aluminum and they can have a negative impact on the conductivity. Thus, according to one embodiment, the addition of these elements is therefore preferably to be avoided.

[0120] Mg, Zn and / or Li:

[0121] 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% each and in total. According to a variant, the elements Cr, V, Ti and / or Mn may be present in the aluminum alloy in a mass fraction of greater than 500 ppm, or greater than 0.10%, or greater than 0.20% each and in total.

[0122] 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. Excessive addition of these elements can significantly lower the electrical conductivity. Thus, according to one embodiment, the addition of these elements is therefore preferably avoided.

[0123] Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and / or Sn:

[0124] According to the present invention, the elements Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and / or Sn may be present in the aluminum alloy in a mass fraction of 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. Alternatively, the elements Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and / or 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 in total.

[0125] 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. 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.

[0126] Preferably, the various optional elements may be present in the aluminum alloy in a mass fraction of less than 15.00%, or less than 13.00%, or less than 11.00%, or less than 10.00%, or less than 9.00%, or less than 8.00%, or less than 7.00%, or less than 6.00%, or less than 5.50%.

[0127] 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 amounts greater than 0.2%.

[0128] The process may include, following the formation of the layers, i.e. following the formation of the final part, the 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.

[0129] According to a first variant, in order to favor the mechanical properties, the post-manufacturing heat treatment can be carried out:

[0130] - 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;

[0131] - 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.

[0132] 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.

[0133] According to another variant, two-stage post-manufacturing heat treatments can maximize electrical conductivity. These treatments consist of first performing a first stage at a temperature T'1 above 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.

[0134] According to another variant, two-stage post-manufacturing heat treatments can maximize electrical conductivity and / or hardness. These treatments consist of first performing 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.

[0135] According to another variant, three-stage post-manufacturing heat treatments can maximize electrical conductivity and / or hardness. These treatments consist of first performing a first stage at a temperature T'1 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 between 250°C and 450°C for a duration of 0.1 h to 200 h.

[0136] Multi-level treatments with a number of levels greater than 3 can also be considered.

[0137] According to one embodiment, the method may comprise hot isostatic pressing (HIP). The HIP treatment may in particular 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 300°C to 450°C, at a pressure of 500 to 3000 bars and for a duration of 0.5 to 100 hours.

[0138] 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 heat treatment. Thus, preferably, the method does not include solution treatment steps followed by quenching.

[0139] The use of post-manufacturing heat treatment, with manufacturing carried out using an additive manufacturing process, can create stress-relieving conditions that eliminate residual stresses and precipitate hardening phases. This is also referred to as thermal stress relief. 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.

[0140] The possible heat treatment and / or hot isostatic pressing makes it possible in particular to increase the hardness or elastic limit and the electrical conductivity of the product obtained. It should be noted, however, that, generally, the higher the temperature, the more conductivity (electrical or thermal) is favored to the detriment of mechanical resistance.

[0141] 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.

[0142] 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 the shape of the part. In particular, the temperature in the thickness or at the surface of the part can 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 post-manufacturing heat treatment temperature rise, in the aforementioned value ranges, makes it possible to obtain parts with good resistance to thermal cracking.

[0143] 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.

[0144] 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 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.

[0145] 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.

[0146] Optionally, it is possible to carry out mechanical deformation of the part, for example after additive manufacturing and / or before heat treatment.

[0147] 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. Figure 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...20 n, stacked on top of each other, forming the wall 20, each layer corresponding to a weld bead. Each layer 20i...20 n extends in the XY plane, according to a pattern defined by the digital model M.

[0148] The diameter of the filler wire is preferably less than 3 mm. It can be between 0.5 mm and 3 mm and is preferably between 0.5 mm and 2 mm, or even between 1 mm and 2 mm. For example, it is 1.2 mm.

[0149] Other methods are also possible, for example, and in a non-limiting manner:

[0150] - selective laser sintering (SLS);

[0151] - direct metal laser sintering (DMLS); - selective heat sintering (SHS);

[0152] - electron beam melting (EBM);

[0153] - laser melting deposition;

[0154] - direct energy deposition (DED);

[0155] - direct metal deposition (DMD);

[0156] - direct laser deposition (DLD);

[0157] - Laser Deposition Technology;

[0158] - laser net shaping engineering;

[0159] - laser cladding technology;

[0160] - Laser Freeform Manufacturing Technology (LFMT);

[0161] - laser fusion deposition (Laser Metal Deposition or LMD);

[0162] - cold spray (Cold Spray Consolidation or CSC);

[0163] - additive manufacturing by friction (AFS or AFSD, or FSAM, or FS);

[0164] - spark plasma sintering or flash sintering (Field Assisted Sintering Technology, FAST or spark plasma sintering); or

[0165] - Inertia Rotary Friction Welding (IRFW).

[0166] 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).

[0167] The solutions according to the present invention are particularly suitable for applications in the electrical, electronic and heat exchanger fields.

[0168] EXPERIMENTAL EXAMPLES

[0169] Example 1

[0170] The tested alloys were cast in a copper mold using an Induthem VC 650V machine to obtain ingots 130 mm high, 95 mm wide and 5 mm thick.

[0171] 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 of 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.

[0172] Under the laser beam, the metal melts in a pool approximately 500 μm thick. After the laser beam, the metal cools rapidly as in the LPBF process. After laser scanning, a thin surface layer approximately 500 μm 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 are judiciously chosen. Laser scanning of the surface of the different samples was carried out using an AddUp FormUP® 350 selective laser powder bed melting (LPBF) machine. The laser source had a power of 400 W, the vector spacing was 60 μm, the scanning speed was 500 mm / s and the beam diameter was 65 μm.

[0173] 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.

[0174] Figure 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.

[0175] Following each test, a post-heat treatment was applied to some samples. The heat treatment was of the annealing type, at a temperature of 400°C, for 1 hour, or 4 hours, or 7 hours.

[0176] Knoop hardness measurement

[0177] 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 from the same alloy will have a high elastic limit.

[0178] To evaluate the hardness of the remelted layer, the wafers obtained above were cut in the plane perpendicular to the direction of the laser passes and then polished. After polishing, hardness measurements were performed 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. Figure 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.

[0179] Hardness was measured according to the Knoop scale with a 50 g load after laser treatment (in the raw state) and after an additional heat treatment at 400°C for varying durations, allowing in particular to evaluate the alloy's ability to harden during heat treatment and the effect of a possible CIC treatment on the mechanical properties and electrical conductivity.

[0180] Electrical conductivity measurement

[0181] 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 long 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.

[0182] 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 electrical conductivity to the remelted area of ​​the wafer.

[0183] The composition of the tested aluminum alloys is presented in Table 1 below, in mass percentages.

[0184] Two reference alloys were used: composition No. 14, which contains aluminum and the following alloying elements: Fe (0.5%) and Zr (1.2%); composition No. 22, which contains aluminum and the following alloying elements: Fe (1%) and Zr (1.2%). [Table 1]

[0185] Table 2 below shows the Knoop hardness (HK 0.05) and electrical conductivity values ​​measured for each alloy, after laser remelting, in the raw state (0 hours of heat treatment).

[0186] [Table 2]

[0187] Table 3 below shows the Knoop hardness (HK 0.05) 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. [Table 3]

[0188] Table 4 below shows the Knoop hardness (HK 0.05) 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. [Table 4]

[0189] Table 5 below shows the Knoop hardness (HK 0.05) 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.

[0190] [Table 5]

[0191] 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, increased both the electrical conductivity and the Knoop hardness (HK0.05) compared to the raw state.

[0192] For all tested solutions, maximum conductivity was obtained after 7 hours at 400°C.

[0193] For all tested solutions, maximum hardness was obtained after treatment at 400°C for between 1 hour and 7 hours. The time required to maximize hardness appeared to be between 0.5 hours and 10 hours for all tested solutions.

[0194] Increasing the heat treatment time to 400°C for periods greater than 10 hours would further increase thermal conductivity but would lower hardness.

[0195] The choice of final heat treatment can thus be chosen according to the intended application.

[0196] For alloys containing Sc, such as alloy No. 23, a heat treatment temperature of 300 to 400°C for a duration of 0.5 to 10 hours may be optimal to maximize hardness. For example, a temperature of 325°C and a duration of 4 hours.

[0197] Tables 4 and 5 show that several solutions of the invention make it possible to offer a Knoop hardness (HK0.05) higher than that of alloy No. 23 while maintaining an electrical conductivity value higher than 25 MS / m.

[0198] Tables 4 and 5 show that several solutions of the invention make it possible to offer a Knoop hardness (HK0.05) higher than that of alloy No. 23 while maintaining an electrical conductivity value higher than 25 MS / m and a total content of addition elements higher than 3%. The experimental values ​​obtained in the examples above made it possible to determine the following formulas.

[0199] Preferably, according to a first variant of the process according to the present invention, after a post-treatment of 4 hours at 400°C:

[0200] - The conductivity in MS / m is greater than 20, preferably greater than 22, preferably greater than 23, preferably greater than 24, preferably greater than 25; and

[0201] - The conductivity in MS / m and the hardness HK0.05 respect the following relationship:

[0202] 38 < [conductivity + (0.137 x hardness)] < 47; and preferably

[0203] 39 < [conductivity + (0.137 x hardness)] < 46; and more preferably

[0204] 40 < [conductivity + (0.137 x hardness)] < 45.

[0205] Preferably, according to a second variant of the process according to the present invention, after a post-treatment of 7 hours at 400°C:

[0206] - The conductivity in MS / m is greater than 20, preferably greater than 22, preferably greater than 23, preferably greater than 24, preferably greater than 25; and

[0207] - The conductivity in MS / m and the hardness HK0.05 respect the following relationship:

[0208] 39 < [conductivity + (0.137 x hardness)] < 47; and preferably

[0209] 40 < [conductivity + (0.137 x hardness)] < 46; and more preferably

[0210] 41 < [conductivity + (0.137 x hardness)] < 45.

[0211] Example 2: Counterexamples

[0212] Additional tests were carried out under the same conditions as Example 1 above. The alloys in Table 6 were tested (casting then rapid prototyping), and then subjected to Knoop hardness measurements with a 50 g load, in the raw state and after an additional heat treatment at 400°C for varying durations, and electrical conductivity measurements (see Table 7).

[0213] [Table 6] [Table 7]

[0214] The results of the above tests show that the selection of the mandatory elements of the present invention is not random and is justified by a technical effect, which makes it possible to resolve the problem of compromise between hardness and conductivity.

[0215] Example 1 demonstrates that the mandatory elements according to the present invention make it possible to solve this technical problem of a good compromise between hardness and electrical conductivity.

[0216] The additional tests of Example 2 make it possible to demonstrate that if a mandatory element is removed and replaced by another element, for example Ti, Mn or V, then such a good compromise cannot be obtained. Indeed, the compromise obtained by the composition according to the present invention (No. 6 and Tables 2 to 5 above) is better than that obtained by the comparison compositions (No. 24 to 27) for which the electrical conductivity is always lower than that of the composition according to the present invention, and the hardness is often less good after heat treatment.

Claims

CLAIMS Method for manufacturing a part (20) comprising the formation of successive metallic layers (20i...20 n ), superimposed one on the other, each layer being formed by the deposition of a filler metal (15, 25), the filler metal being subjected to an input of energy so as to melt and, upon solidification, to constitute said layer, the process 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, in mass fractions greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferably from 0.40 to 2.00%, more preferably from 0.40 to 1.80%, even more preferably from 0.50 to 1.60%, even more preferably from 0.60 to 1.50%, even more preferably from 0.70 to 1.40%, even more preferably from 0.80 to 1.30% each and in total; - at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, 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; - optionally Fe, according to a mass fraction less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally Ni, according to a mass fraction 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, 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; - optionally Si, 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%; 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 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 at least one alloying element chosen from Cr, V, Ti and Mn, in a mass fraction of less than 0.50%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%, more preferably less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than 0.50%, more preferably less than 0.10%, and even more preferably less than 0.05% in total; - 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%, 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 Li, according to a mass fraction 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 at least one element chosen from: Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, in mass fractions 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. A manufacturing process for a part comprising the formation of successive metallic layers, superimposed one on the other, each layer being formed by the deposition of a filler metal, the filler metal being subjected to an input of energy so as to melt and, upon solidification, constitute 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, and Er, in mass fractions greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferably from 0.40 to 2.00%, more preferably from 0.40 to 1.80%, even more preferably from 0.50 to 1.60%, even more preferably from 0.60 to 1.50%, even more preferably from 0.70 to 1.40%, even more preferably from 0.80 to 1.30% each and in total; - Sc, according to a mass fraction 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%; and according to a mass fraction greater than 500 ppm, preferably greater than 0.10%, preferably greater than 0.15%, preferably greater than 0.20%; - optionally at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, 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; - optionally Fe, according to a mass fraction less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally Ni, according to a mass fraction 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, 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; - optionally Si, 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%; in one embodiment, the Si content is less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally at least one alloying element chosen from Cr, V, Ti and Mn, in a fraction less than 0.50%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%, more preferably less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than 0.50%, more preferably less than 0.10%, even more preferably less than 0.05% in total; - 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%, 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 Li, according to a mass fraction 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 at least one element chosen from: Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, 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; - impurities: < 0.05% individually, and preferably < 0.15% in total; remainder aluminum. Process according to any one of the preceding claims, comprising, following the formation of the layers (20i...20 n ), that is to say, following the formation of the final piece, a application of a post-manufacturing heat treatment, preferably tempering or annealing.

4. A process according to any one of the preceding claims, not comprising solution treatment and / or quenching following layer formation, i.e. following the formation of the final part, or following post-fabrication heat treatment.

5. A 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.

6. A method according to any one of the preceding claims, wherein the filler metal is in 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...20 n ).

7. A method according to any one of claims 1 to 5, wherein the filler metal is obtained 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...20 n ).

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

9. Metal part according to claim 8, characterized in that, after a post-treatment of 4 hours at 400°C: - The conductivity in MS / m is greater than 20, preferably greater than 22, preferably greater than 23, preferably greater than 24, preferably greater than 25; and - The conductivity in MS / m and the hardness HK0.05 follow the following relationship: 38 < [conductivity + (0.137 x hardness)] < 47; and preferably 39 < [conductivity + (0.137 x hardness)] < 46; and more preferentially 40 < [conductivity + (0.137 x hardness) ] < 45.

10. Metal part according to claim 8, characterized in that, after a post-treatment of 7 hours at 400°C: - The conductivity in MS / m is greater than 20, preferably greater than 22, preferably greater than 23, preferably greater than 24, preferably greater than - The conductivity in MS / m and the hardness HK0.05 follow the following relationship: 39 < [conductivity + (0.137 x hardness)] < 47; and preferably 40 < [conductivity + (0.137 x hardness)] < 46; and more preferably 41 < [conductivity + (0.137 x hardness) ] < 45. Powder, intended for use as a filler material in 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, and Er, in mass fractions greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferably from 0.40 to 2.00%, more preferably from 0.40 to 1.80%, even more preferably from 0.50 to 1.60%, even more preferably from 0.60 to 1.50%, even more preferably from 0.70 to 1.40%, even more preferably from 0.80 to 1.30% each and in total; - at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, 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; - optionally Fe, according to a mass fraction less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally Ni, according to a mass fraction 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, 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; - optionally Si, 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%; 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 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 at least one alloying element chosen from Cr, V, Ti and Mn, in a fraction less than 0.50%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%, more preferably less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than 0.50%, more preferably less than 0.1%, even more preferably less than 0.05% in total; - 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%, 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 Li, according to a mass fraction 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 at least one element chosen from: Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, 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; - impurities: < 0.05% individually, and in total < 0.15%; remainder aluminum. Powder, intended for use as a filler material in 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, and Er, in mass fractions greater than or equal to 0.30%, preferably from 0.30 to 2.50%, preferably from 0.40 to 2.00%, more preferably from 0.40 to 1.80%, even more preferably from 0.50 to 1.60%, even more preferably from 0.60 to 1.50%, even more preferably from 0.70 to 1.40%, even more preferably from 0.80 to 1.30% each and in total; - Sc, according to a mass fraction 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%; and according to a mass fraction greater than 500 ppm, preferably greater than 0.10%, preferably greater than 0.15%, preferably greater than 0.20%; - optionally at least one alloying element chosen from: Co, La, Ce, mischmetal, W, Ta, Mo and Nb, 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; - optionally Fe, according to a mass fraction less than 3.00%, preferably less than 2.00%, preferably less than 1.00%, preferably less than 0.50%; - optionally Ni, according to a mass fraction 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, 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; - optionally Si, 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%; in one embodiment, the Si content is less than 0.30%, preferably less than 0.20%, preferably less than 0.10%; - optionally at least one alloying element chosen from Cr, V, Ti and Mn, in a fraction less than 0.50%, preferably less than 0.30%, preferably less than 0.20%, preferably less than 0.10%, more preferably less than 0.05% each and less than or equal to 2.00%, preferably less than or equal to 1.00%, preferably less than 0.50%, more preferably less than 0.1%, even more preferably less than 0.05% in total; - 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%, 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 Li, according to a mass fraction 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 at least one element chosen from: Nd, Y, Tm, Lu, Yb, Sr, Ba, Sb, Bi, Ca, P, B, In and Sn, 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; - impurities: < 0.05% individually, and in total < 0.15%; remainder aluminum. Use of a powder according to claim 11 or 12, in a manufacturing process selected from: EBM (electron beam melting), cold spraying (CSC or CS), laser melting deposition (LMD), friction additive manufacturing (AFS or AFSD, or FSAM, or FS), spark plasma sintering (FAST) or rotary friction welding (IRFW), preferably cold spraying (CSC).

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