METHOD FOR MANUFACTURING AN ALUMINUM ALLOY PART

Description

TECHNICAL FIELD

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

[0002] 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.

[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 was described in document WO2015 / 006447. 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.

[0004] One method of additive manufacturing is the melting or sintering of a powdered filler material. This can be done by melting or sintering using an energy beam.

[0005] Examples include selective laser sintering (SLS) or direct metal laser sintering (DMLS), in which a layer of metal or metal alloy powder is applied to the workpiece and is selectively sintered according to the digital model with thermal energy from a laser beam. Another type of metal forming process includes selective laser melting (SLM) or electron beam melting (EBM), in which thermal energy from a laser or directed electron beam is used to selectively melt (instead of sinter) the metal powder so that it fuses as it cools and solidifies.

[0006] We also know laser melting deposition (LMD) in which the powder is projected and melted by a laser beam simultaneously.

[0007] Patent application WO2016 / 209652 describes a method for manufacturing high strength aluminum comprising: preparing an atomized aluminum powder having one or more desired approximate powder sizes and an approximate morphology; sintering the powder to form a product by additive manufacturing; solution processing; quenching; and tempering the additively manufactured aluminum.

[0008] Patent application US2017 / 0016096 describes a method for manufacturing a part by localized fusion, in particular obtained by exposing a powder to an energy beam of the electron beam or laser beam type, the powder being made of an aluminum alloy whose copper content is between 5% and 6% by mass, the magnesium content being between 2.5% and 3.5% by mass.

[0009] Patent application EP2796229 discloses a method for forming a dispersion-strengthened aluminum metal alloy comprising the steps of: obtaining, in powder form, an aluminum alloy composition that is capable of acquiring a dispersion-strengthened microstructure; directing a low-energy density laser beam onto a portion of the powder having the alloy composition; removing the laser beam from the portion of the powdered alloy composition; and cooling the portion of the powdered alloy composition at a rate greater than or equal to about 10 6< °C per second, thereby forming the dispersion-strengthened aluminum metal alloy.The method is particularly suitable for an alloy having a composition according to the following formula: Al comp Fe a Si b X c , wherein X represents at least one element selected from the group consisting of Mn, V, Cr, Mo, W, Nb and Ta; "a" ranges from 2.0 to 7.5 atomic %; "b" ranges from 0.5 to 3.0 atomic %; "c" ranges from 0.05 to 3.5 atomic %; and the balance is aluminum and incidental impurities, provided that the ratio [Fe+Si] / Si is in the range of about 2.0:1 to 5.0:1.

[0010] Patent application US2017 / 0211168 discloses a method for manufacturing a lightweight, high-temperature, high-strength alloy comprising aluminum, silicon, and iron and / or nickel.

[0011] Patent application EP3026135 describes a casting alloy comprising 87 to 99 parts by weight of aluminum and silicon, 0.25 to 0.4 parts by weight of copper and 0.15 to 0.35 parts by weight of a combination of at least two elements from among Mg, Ni and Ti. This casting alloy is adapted to be sprayed by an inert gas to form a powder, the powder being used to form an object by laser additive manufacturing, the object then undergoing a tempering treatment.

[0012] Patent application US2016 / 0138400 describes alloys comprising 3 to 12% by weight of iron, 0.1 to 3% by weight of vanadium, 0.1 to 3% by weight of silicon and 1 to 6% by weight of copper, remaining aluminum and impurities, suitable for additive manufacturing techniques.

[0013] Patent application JPH08143999 discloses an alloy powder comprising 3-7% Fe, 3-12% Ni, 1-7% Si, 0.5-3% Cr, with the remainder Al and impurities.

[0014] The publication "Characterization of Al-Fe-V-Si heat-resistant aluminum alloy components fabricated by selective laser melting", Journal of Material Research, Vol. 30, No. 10, May 28, 2015, describes the SLM fabrication of heat-resistant components of composition, in wt%, Al-8.5Fe-1.3V-1.7Si.

[0015] The publication "Microstructure and mechanical properties of Al-Fe-V-Si aluminum alloy produced by electron beam melting", Materials Science & Engineering A659(2016)207-214, describes parts of the same alloy as in the previous article obtained by EBM.

[0016] There is a growing demand for high-strength aluminum alloys for SLM application. 4xxx alloys (mainly Al10SiMg, Al7SiMg and Al12Si) are the most mature aluminum alloys for SLM application. These alloys offer very good suitability for the SLM process but suffer from limited mechanical properties.

[0017] Scalmalloy ®< (DE102007018123A1) developed by APWorks offers (with a post-manufacturing heat treatment of 4 hours at 325°C) good mechanical properties at room temperature. However, this solution suffers from a high cost in powder form due to its high scandium content (~ 0.7% Sc) and the need for a specific atomization process. This solution also suffers from poor mechanical properties at high temperatures, for example above 150°C.

[0018] The mechanical properties of aluminum parts obtained by additive manufacturing depend on the alloy forming the filler metal, and more precisely on its composition, the parameters of the additive manufacturing process as well as the heat treatments applied. The inventors have determined an alloy composition which, used in an additive manufacturing process, makes it possible to obtain parts having remarkable characteristics. In particular, the parts obtained according to the present invention have improved characteristics compared to the prior art (in particular an 8009 alloy), in particular in terms of surface quality, resistance to hot cracking, or even hot hardness (for example after 4 hours at 400°C). STATEMENT OF THE INVENTION

[0019] A first object of the invention is a method of manufacturing a part according to claim 1.

[0020] Optionally, the alloy may also comprise at least one element chosen from: Mn, Ti, W, Nb, Ta, Y, Yb, Nd, Er, Cr, Zr, Hf, Sc, Ce and / or mischmetal, according to a mass fraction less than or equal to 5%, preferably less than or equal to 3% each, and less than or equal to 15%, preferably less than or equal to 12%, even more preferably less than or equal to 5% in total. However, in one embodiment, the addition of Sc is avoided, the preferred mass fraction of Sc then being less than 0.05%, and preferably less than 0.01%. These elements may lead to the formation of dispersoids or fine intermetallic phases making it possible to increase the hardness of the material obtained.

[0021] Optionally, the alloy may also comprise at least one element chosen from: Sr, Ba, Sb, Bi, Ca, P, B, In and / or Sn, according to a mass fraction less than or equal to 1%, preferably less than or equal to 0.1%, even more preferably less than or equal to 700 ppm each, and less than or equal to 2%, preferably less than or equal to 1% in total. However, in one embodiment, the addition of Bi is avoided, the preferred mass fraction of Bi then being less than 0.05%, and preferably less than 0.01%.

[0022] Optionally, the alloy may also comprise at least one element chosen from: Ag in a mass fraction of 0.06 to 1%, Li in a mass fraction of 0.06 to 1%, Cu in a mass fraction of 0.06 to 5%, preferably 0.1 to 2%, Zn in a mass fraction of 0.06 to 1% and / or Mg in a mass fraction of 0.06 to 1%. These elements may act on the strength of the material by hardening precipitation or by their effect on the properties of the solid solution.

[0023] However, the addition of Mg is not recommended and the Mg content is preferably kept below an impurity value of 0.05% by mass.

[0024] Optionally, the alloy may also comprise at least one compound for refining the grains and avoiding a coarse columnar microstructure, for example AlTiC or AlTiB2 (for example in AT5B or AT3B form), in an amount less than or equal to 50 kg / ton, preferably less than or equal to 20 kg / ton, even more preferably less than or equal to 12 kg / ton each, and less than or equal to 50 kg / ton, preferably less than or equal to 20 kg / ton in total.

[0025] According to one embodiment, the method may comprise, following the formation of the layers: solution treatment followed by quenching and tempering, or heat treatment typically at a temperature of at least 100°C and at most 400°C, and / or hot isostatic pressing (HIP).

[0026] Heat treatment can in particular allow for the sizing of residual stresses and / or additional precipitation of hardening phases.

[0027] CIC treatment can notably improve elongation and fatigue properties. Hot isostatic pressing can be performed before, after or instead of heat treatment.

[0028] Advantageously, hot isostatic pressing is carried out at a temperature of 250°C to 550°C and preferably 300°C to 450°C, at a pressure of 500 to 3000 bars and for a duration of 0.5 to 10 hours.

[0029] Heat treatment and / or hot isostatic pressing in particular makes it possible to increase the hardness of the product obtained.

[0030] According to another embodiment, suitable for structurally hardened alloys, solution treatment followed by quenching and tempering of the formed part and / or hot isostatic pressing can be carried out. Hot isostatic pressing can in this case advantageously replace solution treatment. 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.

[0031] 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.

[0032] Optionally, it is possible to carry out mechanical deformation of the part, for example after additive manufacturing and / or before heat treatment.

[0033] Other advantages and characteristics will emerge more clearly from the description which follows and from the non-limiting examples, and represented in the figures listed below. FIGURES

[0034] [ Fig. 1 ] There Figure 1 is a diagram illustrating an additive manufacturing process of the SLM, or EBM, type. [ Fig. 2 ] There Figure 2 shows a micrograph of a cross-section of an Al10Si0.3Mg sample after surface scanning with a laser, cut and polished with two Knoop indentations in the recast layer. DETAILED DESCRIPTION OF THE INVENTION

[0035] In the description, unless otherwise indicated: The designation of aluminum alloys is in accordance with the nomenclature established by The Aluminum Association; the chemical element contents are designated in % and represent mass fractions.

[0036] There Figure 1generally describes an embodiment, in which the additive manufacturing method according to the invention is implemented. According to this method, the filler material 25 is in the form of an alloy powder according to the invention. An energy source, for example a laser source or an electron source 31, emits an energy beam, for example a laser beam or an electron beam 32. The energy source is coupled to the filler material by an optical or electromagnetic lens system 33, the movement of the beam can thus be determined according to a digital model M. The energy beam 32 follows a movement along the longitudinal plane XY, describing a pattern dependent on the digital model M. The powder 25 is deposited on a support 10. The interaction of the energy beam 32 with the powder 25 causes a selective melting of the latter, followed by solidification, resulting in the formation of a layer 20 1 ...20 n .When a layer has been formed, it is covered with powder 25 of the filler metal and another layer is formed, superimposed on the previously produced layer. The thickness of the powder forming a layer can for example be 10 to 100 µm. This additive manufacturing method is typically known as selective laser melting (SLM) when the energy beam is a laser beam, the process in this case being advantageously carried out at atmospheric pressure, and as electron beam melting (EBM) when the energy beam is an electron beam, the process in this case being advantageously carried out at reduced pressure, typically less than 0.01 bar and preferably less than 0.1 mbar.

[0037] In another embodiment, the layer is obtained by selective laser sintering (SLS or direct metal laser sintering, DMLS), the layer of alloy powder according to the invention being selectively sintered according to the chosen digital model with thermal energy supplied by a laser beam.

[0038] In yet another embodiment not described by the figure 1 , the powder is projected and melted simultaneously by a beam, usually a laser. This process is known as laser melting deposition.

[0039] Other processes that may be used include those known as Direct Energy Deposition (DED), Direct Metal Deposition (DMD), Direct Laser Deposition (DLD), Laser Deposition Technology (LDT), Laser Metal Deposition (LMD), Laser Engineering Net Shaping (LENS), Laser Cladding Technology (LCT), or Laser Freeform Manufacturing Technology (LFMT).

[0040] In one embodiment, the method according to the invention is used for the production of a hybrid part comprising a part 10 obtained by conventional rolling and / or extrusion and / or molding and / or forging processes optionally followed by machining and an integral part 20 obtained by additive manufacturing. This embodiment may also be suitable for the repair of parts obtained by conventional processes.

[0041] In one embodiment of the invention, it is also possible to use the method according to the invention for the repair of parts obtained by additive manufacturing.

[0042] After forming the successive layers, we obtain a raw part or part in its raw manufacturing state.

[0043] The metal parts obtained by the method according to the invention are particularly advantageous because they have smooth surfaces and do not exhibit hot cracking. On the other hand, they have a hardness in the as-manufactured state lower than that of an 8009 reference, and at the same time a hardness after heat treatment higher than that of an 8009 reference. Thus, unlike alloys according to the prior art such as alloy 8009, the hardness of the alloys according to the present invention decreases less between the as-manufactured state and the state after heat treatment. The lower hardness in the as-manufactured state of the alloys according to the present invention compared to an 8009 alloy is considered advantageous for the suitability for the SLM process, by inducing a lower level of stresses during SLM manufacturing and thus a lower sensitivity to hot cracking.The higher hardness after heat treatment (e.g. 1h at 400°C) of the alloys according to the present invention compared to an 8009 alloy provides better thermal stability. The heat treatment could be a post-SLM hot isostatic pressing (HIP) step. Thus, the alloys according to the present invention are softer in the as-manufactured state but have better hardness after heat treatment, resulting in better mechanical properties for the parts in service.

[0044] The Knoop 10g hardness in the as-manufactured state of the metal parts obtained according to the present invention is preferably 150 to 350 HK, more preferably 200 to 340 HK. Preferably, the Knoop 10g hardness of the metal parts obtained according to the present invention, after a heat treatment of at least 100°C and at most 550°C and / or hot isostatic pressing, is 150 to 300 HK, more preferably 160 to 250 HK. The method for measuring the Knoop hardness is described in the examples below.

[0045] The powder according to the present invention may have at least one of the following characteristics: average particle size of 10 to 100 µm, preferably 20 to 60 µm; 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; low porosity, preferably 0 to 5%, more preferably 0 to 2%, even more preferably 0 to 1% by volume. Porosity can, in particular, be determined by scanning electron microscopy or 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 powder size), so-called satellites, which stick to the larger particles.

[0046] The powder according to the present invention can be obtained by conventional atomization methods from an alloy according to the invention in liquid or solid form or, alternatively, the powder can be obtained by mixing primary powders before exposure to the energy beam, the different compositions of the primary powders having an average composition corresponding to the composition of the alloy according to the invention.

[0047] Infusible, non-soluble particles, for example oxides or TiB 2 particles or carbon particles, may also be added to the bath before atomizing the powder and / or during powder deposition and / or during mixing of the primary powders. These particles may be used to refine the microstructure. They may also be used to harden the alloy if they are of nanometric size. These particles may be present in a volume fraction of less than 30%, preferably less than 20%, more preferably less than 10%.

[0048] The powder according to the present invention can be obtained for example by gas jet atomization, plasma atomization, water jet atomization, ultrasonic atomization, centrifugal atomization, electrolysis and spheroidization, or grinding and spheroidization.

[0049] Preferably, the powder according to the present invention is obtained by gas jet atomization. The gas jet atomization process begins with the pouring of a molten metal through a nozzle. The molten metal is then hit by jets of neutral gases, such as nitrogen or argon, and atomized into very small droplets which cool and solidify as they fall inside an atomization tower. The powders are then collected in a can. The gas jet atomization process has the advantage of producing a powder with a spherical shape, unlike water jet atomization which produces a powder with an irregular shape. Another advantage of gas jet atomization is good powder density, particularly due to the spherical shape and particle size distribution. Yet another advantage of this process is good reproducibility of the particle size distribution.

[0050] After its manufacture, the powder according to the present invention can be steamed, in particular in order to reduce its humidity. The powder can also be packaged and stored between its manufacture and its use.

[0051] The powder according to the present invention can in particular be used in the following applications: Selective Laser Sintering (SLS); Direct Metal Laser Sintering (DMLS); Selective Heat Sintering (SHS); Selective Laser Melting (SLM); Electron Beam Melting (EBM); Laser Melting Deposition (LDM); Direct Energy Deposition (DED); Direct Metal Deposition (DMD); Direct Laser Deposition (DLD); Laser Deposition Technology (LDT); Laser Engineering Net Shaping (LENS); Laser Cladding Technology (LCT);Laser Freeform Manufacturing Technology (LFMT); Laser Metal Deposition (LMD); Cold Spray Consolidation (CSC); Additive Friction Stir (AFS); Field Assisted Sintering Technology (FAST); or Inertia Rotary Friction Welding (IRFW).

[0052] The invention will be described in more detail in the following example.

[0053] The invention is not limited to the embodiments described in the above description or in the examples below, and may vary widely within the scope of the invention as defined by the claims appended to this description. EXAMPLES

[0054] Different alloys according to the present invention, called Innov1, Innov2 and Innov3, and a prior art 8009 alloy were cast in a copper mold using an Induthem VC 650V machine to obtain ingots of 130 mm height, 95 mm width and 5 mm thickness. The composition of the alloys, obtained by ICP, is given in percentage of mass fraction in the following Table 1. [Table 1] Alloys If Fe V Neither Co There Ba Sb Sn Reference (8009) 1,8 8,65 1,3 - - - - - - Innov1 1,95 3,92 1,22 5,16 - - - - - Innov2 1,91 3,88 1,14 - 4,83 - - - - Innov3 1,82 6,45 1,1 - - 4,78 0,025 0,054 0,050

[0055] The refining compound AT5B was added to the Innov1 and Innov2 alloys, in a quantity of 10 kg / tonne. Example 1: SLM on disks

[0056] The alloys as described in Table 1 above were tested by a rapid prototyping method. Samples were machined for surface scanning with a laser, in the form of discs of thickness 5 mm and diameter 27 mm, from the ingots obtained above. The discs were placed in an SLM machine and surface scans were carried out with a laser following the same scanning strategy and process conditions representative of those used for the SLM process. It was indeed found that it was possible in this way to evaluate the suitability of the alloys for the SLM process and in particular the surface quality, sensitivity to hot cracking, hardness in the raw state and hardness after heat treatment.

[0057] Under the laser beam, the metal melts in a 10 to 350 µm thick bath. After the laser beam, the metal cools rapidly as in the SLM process. After laser scanning, a thin 10 to 350 µm thick surface layer was melted and then solidified. The properties of the metal in this layer are close to the properties of the metal at the heart of a part manufactured by SLM, because the scanning parameters are judiciously chosen. The laser scanning of the surface of the different samples was carried out using a PM100 selective laser melting machine from Phénix systems. The laser source had a power of 200 W, the manufacturing temperature was 200°C, the vector deviation was 50 µm and the beam diameter was 60 to 80 µm. Two different scanning speeds were tested for each sample: 600 mm / s and 900 mm / s. 1) Sensitivity to hot cracking

[0058] It is known that some alloys cannot be used in SLM because the samples crack during SLM construction. It has been shown that this cracking can also be achieved by scanning the surface with a laser. Thus, this method (scanning the surface with a laser) makes it possible to simulate an SLM process and eliminate alloys that would crack during the SLM process.

[0059] The discs obtained above were cut in the plane perpendicular to the direction of the laser passes and then polished. The sensitivity to hot cracks (during surface scanning with the laser) was evaluated by metallographic observations (x200) on cross-sections of the treated areas. The results are summarized in Table 2 below. Rating 1 corresponds to the absence of microcracks, rating 2 to the presence of microcracks of less than 50 µm, and rating 3 to the presence of microcracks of more than 50 µm. [Table 2] Alloy Quoting Reference (8009) 3 Innov1 1 Innov2 2 Innov3 1

[0060] Thus, according to Table 2 above, only the alloys according to the present invention make it possible to obtain good resistance to hot cracking. On the other hand, a smooth surface with few or no defects was observed. 2) Knoop hardness measurement

[0061] 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 potentially have a high fracture limit.

[0062] To evaluate the hardness of the recast layer, the discs 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 recast layer. The hardness measurement was carried out with a Struers Durascan model device. The Knoop 10 g hardness method with the long diagonal of the indentation placed parallel to the plane of the recast layer was chosen to keep sufficient distance between the indentation and the edge of the sample. 15 indentations were positioned at the mid-thickness of the recast layer. Figure 2 shows an example of the hardness measurement. Reference 1 corresponds to the recast layer and reference 2 corresponds to a Knoop hardness imprint.

[0063] The hardness was measured according to the Knoop scale with a load of 10 g after laser treatment (in the raw state) and after an additional heat treatment at 400°C for 4 h, 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.

[0064] The Knoop 10g hardness values in the raw state and after 4 hours at 400°C are given in Table 3 below (HK). [Table 3] Alloy Knoop hardness 10g in raw state Knoop hardness 10g after 4 hours at 400°C Reference (8009) 359 155 Innov1 261 179 Innov2 272 193 Innov3 331 188

[0065] The alloys according to the present invention (Innov1, Innov2 and Innov3) showed a Knoop 10g hardness in the raw state lower than that of the 8009 alloy, but, after 4h at 400°C, higher than that of the reference 8009 alloy. Without being bound by theory, it is assumed that the higher hardness after 4h at 400°C is most likely associated with slower coagulation kinetics of the dispersoids (better thermal stability). Example 2: SLM on powder

[0066] Ingots cast from the compositions described in Table 1 above were atomized by UTBM (University of Technology of Belfort Montbéliard) to obtain a powder by gas jet atomization (method described above). The particle size analysis of the powders obtained was carried out by laser diffraction using a Malvern Mastersizer 2000 particle size analyzer according to ISO 13320. The curve describing the evolution of the volume fraction as a function of the diameter of the particles forming the powder generally describes a distribution similar to a Gaussian distribution. D 10 , D 50 and D 90 are generally called the 10%, 50% (median) and 90% fractiles of the distribution obtained, respectively.

[0067] The characteristics D 10 , D 50 and D 90 of the powders obtained are given in table 4 below. [Table 4] Alloy D 10 (µm) D 50 (µm) D 90 (µm) Reference (8009) 33,5 52,3 81,2 Innov1 42,3 58,1 81,2 Innov2 39,5 60,7 93,6 Innov3 58,6 88,3 132

[0068] Thus, it is possible to manufacture powders from the alloys according to the invention.

[0069] In this example, parts were produced using the SLM process described above. The tests were carried out on a 400W Renishaw AM 400 machine by UTBM. For each of the Innov1, Innov2 and Innov3 alloys, several 7 mm cubes were produced by varying the process parameters (see Table 5 below). The porosity of the resulting cubes was determined (by polishing and then image analysis) and is given in Table 5 below. [Table 5] Alloy Energy (J / mm 3< ) Speed (mm / s) Volumetric velocity (mm 3 < / s) Porosity 96 891 3,2 2,3 127 714 2,4 0,2 102 833 2,8 0,2 97 776 2,6 0,9 129 776 2,6 0,1 114 825 2,5 0,7 Innov1 95 825 3,0 1,4 118 825 2,7 0,6 95 952 3,1 0,8 124 776 2,3 0,1 104 776 2,8 0,2 92 891 2,9 1,8 116 891 2,23 3,0 96 891 2,67 3,2 127 714 1,96 0,8 102 833 2,29 1,2 129 776 2,13 2,0 Innov2 114 825 2,06 3,2 95 825 2,47 3,3 89 825 2,27 3,2 118 825 2,27 1,1 124 776 1,94 0,8 104 776 2,33 0,9 92 891 2,45 1,8 87 891 2,23 2,7 116 891 2,23 3,0 127 714 1,96 1,0 102 833 2,29 1,2 Innov3 129 776 2,13 0,7 95 825 2,47 3,5 118 825 2,27 0,8 124 776 1,94 1,2 104 776 2,33 2,5

[0070] Thus, it is possible to obtain parts having acceptable porosities with the process according to the present invention. The porosity could be improved by optimizing the process, or even with a post-manufacturing treatment of the CIC (hot isostatic compression) type.

[0071] Furthermore, none of the tested samples exhibited cracking during SLM fabrication.

Claims

1. Method for manufacturing a part including a formation of successive solid metal layers (201...20n), superimposed on each other, each layer describing a pattern defined from a digital model (M), each layer being formed by the deposition of a metal (25), referred to as solder, the solder being subjected to an input of energy so as to start to melt and to constitute, by solidifying, said layer, wherein the solder is in the form of a powder (25), the exposure of which to an energy beam (32) results in melting followed by solidification so as to form a solid layer (201...20n), the method being characterised in that the solder (25) is an aluminium alloy comprising at least the following alloy elements: - Si, in a fraction by weight of 0 to 4%, preferably 0.5 to 4%, more preferentially 1 to 4%, and even more preferentially 1 to 3%; - Fe, in a fraction by weight of 1% to 15%, preferably 2 to 10%; - V, in a fraction by weight of 0 to 5%, preferably 0.5 to 5%, more preferentially 1 to 5%, and even more preferentially 1 to 3%; - at least one element chosen from: Ni, La and / or Co, in a fraction by weight of 3 to 8% each and in a fraction by weight of less than or equal to 15%, preferably less than or equal to 12% in total; - optionally at least one element chosen from Mn, Ti, W, Nb, Ta, Y, Yb, Nd, Er, Cr, Zr, Hf, Sc, Ce and / or mischmetal, in a fraction by weight of less than or equal to 5% each, and less than or equal to 15% in total; - optionally at least one element chosen from: Sr, Ba, Sb, Bi, Ca, P, B, In, and / or Sn, in a fraction by weight of less than or equal to 1% each, and less than or equal to 2% in total; - optionally, at least one element chosen from: Ag in a fraction by weight of 0.06 to 1%, Li in a fraction by weight of 0.06 to 1%, Cu in a fraction by weight of 0.06 to 5%, Zn in a fraction by weight of 0.06 to 1% and / or Mg in a fraction by weight of 0.06 to 1%; - impurities in a fraction by weight of less than 500 ppm each and less than 0.15% in total; - the remainder being aluminium.

2. Method according to claim 1, wherein the fraction by weight of at least one element chosen from: Mn, Ti, W, Nb, Ta, Y, Yb, Nd, Er, Cr, Zr, Hf, Ce, Sc and / or mischmetal, is less than or equal to 3% each, preferably less than or equal to 12%, even more preferentially less than or equal to 5% in total.

3. Method according to any one of the preceding claims, wherein the fraction by weight of at least one element chosen from: Sr, Ba, Sb, Bi, Ca, P, B, In and / or Sn, is less than or equal to 0.1%, preferentially less than or equal to 700 ppm each, and preferably less than or equal to 1% in total.

4. Method according to any one of the preceding claims, wherein the fraction by weight of Cu is 0.1 to 2%.

5. Method according to any one of the preceding claims, wherein the aluminium alloy also comprises at least one compound for refining the grains, for example AlTiC or AlTiB2, in a quantity of less than or equal to 50 kg / tonne, preferably less than or equal to 20 kg / tonne, even more preferentially less than or equal to 12 kg / tonne each, and less than or equal to 50 kg / tonne, preferably less than or equal to 20 kg / tonne in total.

6. Method according to any one of the preceding claims, including, following the formation of the layers (201...20n): - solution heat treatment followed by quenching and aging, or - heat treatment typically at a temperature of at least 100°C and no more than 400°C, - and / or hot isostatic compression.