EP4149702A2

EP4149702A2 - Method for producing an aluminium alloy part

Info

Publication number: EP4149702A2
Application number: EP21731239.6A
Authority: EP
Inventors: Bechir CHEHAB; Ravi Shahani
Original assignee: C Tec Constellium Technology Center SAS
Current assignee: C Tec Constellium Technology Center SAS
Priority date: 2020-05-13
Filing date: 2021-05-10
Publication date: 2023-03-22
Also published as: CA3171031A1; FR3110095A1; DE21731239T1; US20230191489A1; JP2023525784A; WO2021156583A2; CN115551659A; WO2021156583A3; KR20230010034A; FR3110095B1

Abstract

The invention relates to a method for producing a part, comprising the production of successive solid metallic layers (20₁…20_n), each layer being produced by depositing a metal (25) called filler metal, and said method being characterized in that the part has a specific grain structure. The invention also relates to a part obtained by means of this method and an alternative method. The alloy used in the additive manufacturing method of the invention makes it possible to obtain parts with exceptional properties.

Description

DESCRIPTION

Title: Manufacturing process of an aluminum alloy part TECHNICAL FIELD

The technical field of the invention is a process for manufacturing an aluminum alloy part, using an additive manufacturing technique.

PRIOR ART

Since the 1980s, additive manufacturing techniques have developed. They consist in shaping a part by adding material, which is the opposite of machining techniques, which aim to remove material. Once confined to prototyping, additive manufacturing is now operational to manufacture industrial products in series, including metal parts.

The term "additive manufacturing" is defined, according to the French standard XP E67-001, as a "set of processes making it possible to manufacture, layer by layer, by adding material, a physical object from a digital object". ASTM F2792 (January 2012) also defines additive manufacturing. Different modalities of additive manufacturing are also defined and described in standard ISO / ASTM 17296-1. The use of additive manufacturing to produce an aluminum part, with low porosity, has been described in document WO2015 / 006447. The application of successive layers is generally carried out by application of a so-called filler material, then melting or sintering of the filler material using an energy source of the laser beam or electron beam type, plasma torch or electric arc. Whatever additive manufacturing method is applied, the thickness of each added layer is of the order of a few tens or hundreds of microns. One means of additive manufacturing is the melting or sintering of a filler material in the form of a powder. It can be fusion or sintering by an energy beam.

In particular, selective laser sintering techniques (selective laser sintering, SLS or direct metal laser sintering, DMLS) are known, in which a layer of metal or metal alloy powder is applied to the part to be manufactured and is selectively sintered according to the digital model with thermal energy from a laser beam. Another type of metal forming process involves selective laser melting (SLM) or electron beam melting (EBM), in which thermal energy supplied by 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. Also known is deposition by laser fusion (laser melting deposition, LMD) in which the powder is projected and melted by a laser beam simultaneously.

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

There is a growing demand for high strength, high temperature usable aluminum alloys for the SLM application. 4xxx alloys (mainly AllOSiMg, AI7SiMg and AI12SÎ) 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.

The 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 linked to its high scandium content (~ 0.7% Sc) and to the need for a specific atomization process. This solution also suffers from poor mechanical properties at high temperature, for example at temperatures above 150 ° C.

The Addalloy ™ developed by NanoAl (W0201800935A1) is an Al Mg Zr alloy. This alloy suffers from limited mechanical properties at high temperature.

Alloy 8009 (Al Fe V Si), developed by Honeywell (US201313801662) offers good mechanical properties in the as-manufactured state both at room temperature and at high temperature up to 350 ° C. Alloy 8009 however suffers from processability problems (risk of cracking), probably linked to its high hardness in the as-manufactured state. Some studies have been carried out on the impact of the temperature of the build plate on the susceptibility to cracking. Mention may in particular be made of US20190039183, which recommends a temperature of 350 to 500 ° C. for certain aluminum alloys of the 2xxx, 5xxx, 6xxx or 7xxx type. We can also cite the publication entitled "Investigation on reducing distortion by preheating during manufacture of aluminum components using selective laser melting" (Buchbinder et al., Journal of Laser Applications, 26, 2014), which recommends a temperature of 150 to 250 ° C for aluminum alloys of the AISilOMg type. The mechanical properties of aluminum parts obtained by additive manufacturing depend on the alloy forming the filler metal, and more precisely on its composition, on the parameters of the additive manufacturing process as well as on the heat treatments applied. The inventors have determined certain characteristics which, used in an additive manufacturing process, make 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 in terms of elastic limit at 200 ° C. and of susceptibility to cracking during the SLM process.

DISCLOSURE OF THE INVENTION

The inventors have discovered that better control of the granular structure by a judicious choice of the composition and of the process parameters, and in particular a control of the manufacturing temperature (for example of the manufacturing plate), can make it possible to:

- eliminate the problems of sensitivity to cracking;

- maintain a good hardening capacity (difference in mechanical strength at room temperature between the as-manufactured state and the state after heat treatment at approximately 400 ° C.); and

- offer good mechanical performance at ambient temperature and at high temperature. A first object of the invention is a method of manufacturing a part comprising a formation of successive solid metal layers, superimposed on each other, each layer describing a pattern defined from a digital model, each layer being formed by the deposition of a metal, called filler metal, the filler metal being subjected to an energy input so as to melt and to form, by solidifying, said layer, in which the filler metal takes the form of a powder, exposure to an energy beam of which results in melting followed by solidification so as to form a solid layer, the process being characterized in that the part is manufactured at a temperature of 25 to 150 ° C; the method also being characterized in that the part has a grain structure such that the surface fraction of the equiaxed grains each having a surface area of less than 2.16 μm ² is less than 44%, preferably less than 40%, preferably less at 36%; and a grain structure such that the surface fraction of columnar grains is greater than or equal to 22%, preferably greater than or equal to 25%, preferably greater than or equal to 30%; the method also being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements: - Zr, according to a mass fraction greater than or equal to 0.30%, preferably 0.30-2.50%, preferably 0.40-2.00%, more preferably 0.40-1.80%, even more preferentially 0.50-1.60%, even more preferentially 0.60-1.50%, even more preferentially 0.70-1.40%, even more preferentially 0.80-1.20% in total; -

Sc, according to a mass fraction of less than 0.30%, preferably less than 0.20%, preferably less than 0.10%, more preferably less than 0.05%;

- 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%;

- 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 at least one element chosen from: Ni, Mn, Cr and / or Cu, according to a mass fraction of 0.50 to 7.00%, preferably from 1.00 to 6.00% each; preferably, according to a mass fraction of less than 25.00%, preferably less than 20.00%, more preferably less than 15.00% in total;

- optionally at least one element chosen from: Hf, Ti, Er, W, Nb, Ta, Y, Yb, Nd, Ce, Co, Mo, Lu, Tm, V and / or mischmetal, according to a lower mass fraction or equal to 5.00%, preferably less than or equal to 3% each, and less than or equal to 15.00%, preferably less than or equal to 12%, more preferably less than or equal to 5% in total;

- optionally at least one element chosen from: Si, La, Sr, Ba, Sb, Bi, Ca, P, B, In and / or Sn, according to a mass fraction less than or equal to 1.00%, preferably less than or equal to 0.5%, preferably less than or equal to 0.3%, more 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 2.00%, of preferably less than or equal to 1% in total;

- optionally Fe, according to a mass fraction of 0.50 to 7.00%, preferably from 1.00 to 6.00% according to a first variant, or according to a mass fraction less than or equal to 1.00%, preferably less than or equal to 0.5%, preferably less than or equal to 0.3%, more preferably less than or equal to 0.1%, even more preferably less than or equal to 700 ppm according to a second variant;

- optionally at least one element chosen from: Ag according to a mass fraction of 0.06 to 1.00% and / or Li according to a mass fraction of 0.06 to 1.00%;

- optionally impurities according to a mass fraction of less than 0.05% each (i.e. 500 ppm) and less than 0.15% in total;

- the rest being aluminum.

It is known to those skilled in the art that other elements have effects equivalent to those of Zr. Mention may in particular be made of Ti, V, Sc, Hf, Er, Tm, Yb or Lu. Thus, according to a variant of the first subject of the present invention, Zr could be partially replaced by at least one element chosen from: Ti, V , Sc, Hf, Er, Tm, Yb and Lu, preferably up to 90% of the mass fraction of Zr.

A second object of the invention is thus a method of manufacturing a part comprising a formation of successive solid metal layers (20i ... 20 _n ), 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), called the filler metal, the filler metal being subjected to an energy input so as to melt and form , on solidifying, said layer, in which the filler metal takes the form of a powder (25), the exposure of which to an energy beam (32) results in a melting followed by a solidification so as to form a solid layer (20i ... 20 _n ), the method being characterized in that the part is manufactured at a temperature of 25 to 150 ° C; the method also being characterized in that the part has a grain structure such that the surface fraction of the equiaxed grains each having a surface area of less than 2.16 μm ² is less than 44%, preferably less than 40%, preferably less than 36%; and a grain structure such that the surface fraction of columnar grains is greater than or equal to 22%, preferably greater than or equal to 25%, preferably greater than or equal to 30%; the method also being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements: - Zr and at least one element chosen from: Ti, V, Sc, Hf, Er, Tm, Yb and Lu, in a mass fraction greater than or equal to 0.30%, preferably 0.30-2.5%, preferably 0.40-2.5%, more preferably 0.40-1, 80%, even more preferentially 0.50-1.60%, even more preferentially 0.60-1.50%, even more preferentially 0.70-1.40%, even more preferentially 0.80-1.20% in total, knowing that Zr represents from 10 to less than 100% of the ranges of percentages given above;

- 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%; - 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 at least one element chosen from: W, Nb, Ta, Y, Nd, Ce, Co, Mo and / or mischmetal, according to a mass fraction less than or equal to 5.00%, preferably less than or equal to 3 % each, and less than or equal to 15.00%, preferably less than or equal to 12%, more preferably less than or equal to 5% in total;

- optionally impurities in a mass fraction of less than 0.05% each (ie 500 ppm) and less than 0.15% in total;

- the rest being aluminum.

Preferably, the alloy according to the present invention, in particular according to the first and second subjects of the invention, comprises a mass fraction of at least 80%, more preferably of at least 85% of aluminum.

The fusion of the powder can be partial or total. Preferably, 50 to 100% of the exposed powder melts, more preferably 80 to 100%.

Each layer can in particular describe a pattern defined from a digital model. Without being bound by theory, the alloys according to the invention appear to be particularly advantageous for presenting a good compromise between sensitivity to cracking and mechanical strength, in particular in cold traction and at high temperature, for example at 200 ° C.

As demonstrated in the examples below, the grain structure as well as the temperature at which the part is manufactured seem to be major influencing factors on the susceptibility to cracking of the aluminum alloy.

Preferably, in particular according to the first and second objects of the invention, the part is manufactured at a temperature of 50 to 130 ° C, more preferably from 50 to 110 ° C, even more preferably from 80 to 110 ° C, even more preferably from 80 to 105 ° C.

Preferably, in particular according to the first and second objects of the invention, the aluminum alloy comprises:

- Zr, according to a mass fraction of 0.50 to 3.00%, preferably from 0.50 to 2.50%, preferably from 0.60 to 1.40%, more preferably from 0.70 to 1.30 %, even more preferably from 0.80 to 1.20%, even more preferably from 0.85 to 1.15%; even more preferably from 0.90 to 1.10%;

- Mn, according to a mass fraction of 1.00 to 7.00%, preferably from 1.00 to 6.00%, preferably from 2.00 to 5.00%; more preferably from 3.00 to 5.00%, even more preferably from 3.50 to 4.50%;

- Ni, according to a mass fraction of 1.00 to 6.00%, preferably from 1.00 to 5.00%, preferably from 2.00 to 4.00%, more preferably from 2.50 to 3.50 %;

- Optionally Fe, 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%; and preferably greater than or equal to 0.05, preferably greater than or equal to 0.10%;

- optionally Si, according to a mass fraction less than or equal to 1.00%, preferably less than or equal to 0.50%;

- optionally Cu, according to a mass fraction of 1.00 to 5.00%, preferably from 1.00 to 3.00%, preferably from 1.50 to 2.50%.

The elements Hf, Ti, Er, W, Nb, Ta, Y, Yb, Nd, Ce, Co, Mo, Lu, Tm, V and / or mischmetal can lead to the formation of dispersoids or fine intermetallic phases allowing '' increase the hardness of the material obtained. In a manner known to those skilled in the art, the composition of the mischmetal is generally about 45 to 50% cerium, 25% lanthanum, 15 to 20% neodymium and 5% praseodymium. According to one embodiment, the addition of La, Bi, Mg, Er, Yb, Y, Sc and / or Zn is avoided, the preferred mass fraction of each of these elements then being less than 0.05%, and of preferably less than 0.01%.

According to another embodiment, the addition of Fe and / or Si is avoided. However, it is known to those skilled in the art that these two elements are generally present in common aluminum alloys at contents such as defined above. The contents as described above can therefore also correspond to the contents of impurities for Fe and Si.

The elements Ag and Li can act on the resistance of the material by hardening precipitation or by their effect on the properties of the solid solution.

Optionally, in particular according to the first and the second objects of the invention, the alloy can also comprise at least one element for refining the grains, for example AITiC or AITÎB2 (for example in the form AT5B or AT3B), in a smaller quantity or equal to 50 kg / tonne, preferably less than or equal to 20 kg / tonne, even more preferably 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.

A third object of the invention is an alternative process which also makes it possible to solve the problem of sensitivity to cracking while maintaining good mechanical performance in cold and hot traction, for example at 200 ° C., without requiring a test. dissolving / quenching. It is a method of manufacturing a part comprising the formation of successive solid metal layers (20i ... 20 _n ), 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), called the filler metal, the filler metal being subjected to a supply of energy so as to melt and to constitute, by being solidifying, said layer, in which the filler metal takes the form of a powder (25), exposure of which to an energy beam (32) results in melting followed by solidification so as to form a solid layer (20i ... 20 _n ), the method being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements:

- Zr, according to a mass fraction greater than or equal to 0.30%, preferably 0.30-2.50%, preferably 0.40-2.00%, more preferably 0.40-1.80%, even more preferentially 0.50-1.60%, even more preferentially 0.60-1.50%, even more preferentially 0.70-1.40%, even more preferentially 0.80-1.20%;

- Sc, according to a mass fraction of less than 0.30%, preferably less than 0.20%, preferably less than 0.10%, more preferably less than 0.05%;

- the remainder being aluminum; the method also being characterized in that the part is manufactured at a temperature of more than 250 to less than 350 ° C, preferably 280 to 330 ° C. As said previously, it is known to those skilled in the art that other elements have effects equivalent to those of Zr. Mention may in particular be made of Ti, V, Sc, Hf, Er, Tm, Yb or Lu. Thus, according to a variant of the third subject of the present invention, the Zr could be partially replaced by at least one element chosen from: Ti, V , Sc, Hf, Er, T m, Yb and Lu, preferably up to 90% of the mass fraction of Zr.

A fourth object of the invention is thus a method of manufacturing a part comprising a formation of successive solid metal layers (20i ... 20 _n ), 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), called the filler metal, the filler metal being subjected to an energy input so as to melt and form , on solidifying, said layer, in which the filler metal takes the form of a powder (25), the exposure of which to an energy beam (32) results in a melting followed by a solidification so as to form a solid layer (20i ... 20 _n ), the method being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements:

Zr and at least one element chosen from: Ti, V, Sc, Hf, Er, Tm, Yb and Lu, according to a mass fraction greater than or equal to 0.30%, preferably 0.30-2.50%, preferably 0.40-2.00%, more preferably 0.40-1.80%, even more preferably 0.50-1.60%, even more preferably 0.60-1.50%, even more preferably 0.70 -1.40%, even more preferably 0.80-1.20% in total, knowing that Zr represents from 10 to less than 100% of the ranges of percentages given above;

- optionally at least one element chosen from: W, Nb, Ta, Y, Nd, Ce, Co, Mo and / or mischmetal, according to a mass fraction less than or equal to 5.00%, preferably less or equal to 3% each, and less than or equal to 15.00%, preferably less than or equal to 12%, more preferably less than or equal to 5% in total;

- Optionally Fe, according to a mass fraction of 0.50 to 7.00%, preferably from 1.00 to 6.00% according to a first variant; or according to a mass fraction less than or equal to 1.00%, preferably less than or equal to 0.5%, preferably less than or equal to 0.3%, more preferably less than or equal to 0.1%, even more preferably less or equal to 700 ppm according to a second variant;

- the remainder being aluminum; the method also being characterized in that the part is manufactured at a temperature of more than 250 to less than 350 ° C, preferably 280 to 330 ° C.

According to the present invention, the part is manufactured either at a temperature of 25 to 150 ° C, preferably from 50 to 130 ° C, more preferably from 50 to 110 ° C, even more preferably from 80 to 110 ° C, even more preferably from 80 to 105 ° C, or at a temperature of more than 250 to less than 350 ° C, preferably 280 to 330 ° C. These two optimized temperature selections are described in more detail in the examples below. There are several ways to heat the manufacturing enclosure of a part (and therefore the powder bed) in additive manufacturing. One can cite for example the use of a heating construction plate, or then heating by a laser, by induction, by heating lamps or by heating resistors which can be placed below and / or inside build plate, and / or around the powder bed.

According to one embodiment, the method can be a construction method with a high deposition rate. The deposition rate may for example be greater than 4 mm ³ / s, preferably greater than 6 mm ³ / s, more preferably greater than 7 mm ³ / s. The deposit rate is calculated as the product of the scanning speed (in mm / s), the vector deviation (in mm) and the layer thickness (in mm).

According to one embodiment, the method can use a laser, and optionally several lasers.

According to one embodiment, the method may comprise, following the formation of the layers:

a heat treatment typically at a temperature of at least 100 ° C and at most 500 ° C, preferably from 300 to 450 ° C; and or

- hot isostatic compression (CIC).

The heat treatment can in particular allow a stress relieving of the residual stresses and / or an additional precipitation of hardening phases.

The CIC treatment can in particular make it possible to improve the elongation properties and the fatigue properties. Hot isostatic pressing can be performed before, after or instead of heat treatment.

Advantageously, the hot isostatic compression is carried out at a temperature of 250 ° C to 550 ° C and preferably of 300 ° C to 450 ° C, at a pressure of 500 to 3000 bars and for a period of 0.5 to 10 time.

According to another embodiment, suitable for age-hardening alloys, it is possible to carry out a solution followed by quenching and tempering of the part formed and / or hot isostatic compression. Hot isostatic compression can in this case advantageously replace dissolution. However, the process according to the invention is advantageous because it preferably does not require a solution treatment followed by quenching. Dissolution can have a detrimental effect on the mechanical strength in certain cases by participating in an enlargement of the dispersoids or of the fine intermetallic phases. Moreover, on parts of complex shape, the quenching operation could lead to distortion of the parts, which would limit the primary advantage of using additive manufacturing, which is obtaining parts directly in their shape. final or near-final.

According to one embodiment, the method according to the present invention also 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.

Optionally, it is possible to achieve a mechanical deformation of the part, for example after additive manufacturing and / or before the heat treatment. Optionally, it is possible to carry out an assembly operation with one or more other parts, by known assembly methods. One can cite for example as assembly method:

- bolting, riveting or other methods of mechanical assembly;

- fusion welding;

- friction welding;

- brazing.

A fifth object of the invention is a metal part, obtained by a process according to the first or the second object of the invention, characterized in that it has a grain structure such that the surface fraction of the equiaxed grains each having a area less than 2.16 μm ² is less than 44%, preferably less than 40%, preferably less than 36%; and such that the surface fraction of columnar grains is greater than or equal to 22%, preferably greater than or equal to 25%, more preferably greater than or equal to 30%.

A sixth object of the invention is a powder comprising, preferably consisting of, an aluminum alloy comprising at least the following alloying elements:

- Zr, according to a mass fraction of 0.30-1.40%, preferably 0.40-1.40%, more preferably 0.50-1.40%, even more preferably 0.60-1, 40%, even more preferably 0.70-1.40%, even more preferably 0.80-1.20%;

- the rest being aluminum.

As said previously, it is known to those skilled in the art that other elements have effects equivalent to those of Zr. Mention may in particular be made of Ti, V, Sc, Hf, Er, Tm, Yb or Lu. Thus, according to a variant of the aluminum alloy of the powder according to the present invention, the Zr could be partially replaced by at least one. element chosen from: Ti, V, Sc, Hf, Er, Tm, Yb and Lu, preferably up to 90% of the mass fraction of Zr.

A seventh object of the invention is thus a powder comprising, preferably consisting of, an aluminum alloy which comprises at least the following alloy elements:

- Zr and at least one element chosen from: Ti, V, Sc, Hf, Er, Tm, Yb and Lu, according to a mass fraction of 0.30-1.40%, preferably 0.40-1.40% , more preferably 0.50-1.40%, even more preferably 0.60-1.40%, even more preferably 0.70-1.40%, even more preferably 0.80-1.20 % in total, knowing that Zr represents from 10 to less than 100% of the ranges of percentages given above;

- Zn, in 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%;

- the rest being aluminum.

Preferably, the alloy of the powder and of the alternative process according to the present invention comprises a mass fraction of at least 80%, more preferably of at least 85% of aluminum.

Preferably, the aluminum alloy of the powder (sixth and seventh objects of the invention) and of the alternative process (third and fourth objects of the invention) according to the present invention comprises:

The aluminum alloy of the powder and of the alternative process according to the present invention can also optionally comprise at least one element chosen to refine the grains, for example AITiC or AITÎB2 (for example in the form AT5B or AT3B), in a lower quantity. or equal to 50 kg / tonne, preferably less than or equal to 20 kg / tonne, even more preferably 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.

Preferably, the addition of La, Bi, Mg, Er, Yb, Y, Sc and / or Zn is avoided, the preferred mass fraction of each of these elements then being less than 0.05%, and preferably less than 0.01%. According to another embodiment, the addition of Fe and / or Si is avoided. However, it is known to those skilled in the art that these two elements are generally present in common aluminum alloys at contents such as defined above. The contents as described above can therefore also correspond to the contents of impurities for Fe and Si.

Other advantages and characteristics will emerge more clearly from the description which follows and from the nonlimiting examples, and shown in the figures listed below.

FIGURES

[Fig. 1] Figure 1 is a diagram illustrating an additive manufacturing process of SLM type, or EBM. [Fig. 2] Figure 2 shows a cracking specimen as used in the examples. Reference 1 corresponds to the face used for metallographic observations, reference 2 to the critical crack measurement zone, reference 3 to the manufacturing direction.

[Fig. 3] Figure 3 is a test specimen geometry used to perform tensile testing, as used in the examples.

DETAILED DESCRIPTION OF THE INVENTION In the description, unless otherwise indicated:

- the designation of aluminum alloys conforms to the nomenclature established by The Aluminum Association;

- the contents of chemical elements are designated in% and represent mass fractions.

FIG. 1 generally describes an embodiment, in which the additive manufacturing method according to the invention is implemented. According to this process, 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 system or electromagnetic lenses 33, the movement of the beam can thus be determined as a function of a digital model M. The energy beam 32 follows a movement along the longitudinal plane XY, describing a pattern depending on the digital model M The powder 25 is deposited on a building plate 10. The interaction of the energy beam 32 with the powder 25 generates 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 of the filler metal and another layer is formed, superimposed on the layer previously produced. The thickness of the powder forming a layer may for example be 10 to 200 µm. This mode of additive manufacturing is typically known under the name of selective laser melting (SLM) when the energy beam is a laser beam, the process being in this case advantageously carried out at atmospheric pressure, and under the name electron beam melting EBM when the energy beam is an electron beam, the process being in this case advantageously carried out at reduced pressure, typically less than 0.01 bar and preferably less than 0.1 mbar.

In another embodiment, the layer is obtained by selective laser sintering (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 digital model chosen with thermal energy supplied by a laser beam.

In yet another embodiment not described by FIG. 1, the powder is projected and melted simultaneously by a generally laser beam. This process is known as laser melting deposition.

Other processes can be used, in particular those known under the names of direct energy deposition (DED), direct metal deposition (Direct Metal Deposition, DMD), direct laser deposition (Direct Laser Deposition, DLD). ), laser deposition technology (Laser Deposition Technology, LDT), laser metal deposition (Laser Metal Deposition, LMD), laser clean shape engineering (Laser Engineering Net Shaping, LENS), laser plating technology (Laser Cladding Technology, LCT), or laser freeform manufacturing technology (LFMT).

In one embodiment, the method according to the invention is used for producing a hybrid part comprising a part obtained by conventional rolling and / or extrusion and / or molding and / or forging methods, optionally followed by machining and an integral part obtained by additive manufacturing. This embodiment may also be suitable for repairing parts obtained by conventional methods.

It is also possible, in one embodiment of the invention, to use the method according to the invention for the repair of parts obtained by additive manufacturing.

At the end of the formation of the successive layers, a blank part or part in the as-manufactured state is obtained.

According to one embodiment, the elastic limit measured at ambient temperature of the part in the as-manufactured state obtained according to the present invention is less than 450 MPa, preferably less than 400 MPa, more preferably 200 to 400 MPa, and again more preferably from 200 to 350 MPa.

According to one embodiment, the elastic limit measured at ambient temperature of a part according to the present invention after a heat treatment not comprising any dissolving or quenching operation is greater than the elastic limit of this same part at l. raw state of manufacture. Preferably, the elastic limit measured at ambient temperature of a part according to the present invention after a heat treatment such as that mentioned above is greater than 350 MPa, preferably greater than 400 MPa.

According to one embodiment, the elastic limit of the part measured at high temperature remains high. Indeed, the elastic limit measured at 200 ° C, for a part in the as-manufactured state or after a stress relieving treatment at less than 350 ° C., remains greater than 50%, preferably greater than 60%, of the elastic limit measured at ambient temperature.

The powder used according to the present invention can exhibit at least one of the following characteristics:

- average particle size from 3 to 100 μm, preferably from 5 to 25 μm, or from 20 to 60 μm. The values given mean that at least 80% of the particles have an average size within the specified range;

- spherical shape. The sphericity of a powder can for example be determined using a morphogranulometer;

- good flowability. The flowability of a powder can for example be determined according to standard ASTM B213 or standard ISO 4490: 2018. According to ISO 4490: 2018, the flow time is preferably less than 50 s;

- low porosity, preferably from 0 to 5%, more preferably from 0 to 2%, even more preferably from 0 to 1% by volume. The porosity can in particular be determined by scanning electron microscopy or by helium pycnometry (see standard ASTM B923);

- absence or small 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.

The powder used according to the present invention can be obtained by conventional atomization processes 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.

It is also possible to add infusible, insoluble particles, for example oxides or particles of titanium diboride T1B2 or particles of titanium carbide TiC, in the bath before the atomization of the powder and / or during the deposition of the powder. powder and / or when mixing the primary powders. These particles can be used to refine the microstructure. They can also be used to harden the alloy if they are nanometric in size. These particles can be present in a volume fraction of less than 30%, preferably less than 20%, more preferably less than 10%.

The powder used according to the present invention can be obtained, for example, by gas jet atomization, plasma atomization, water jet atomization, ultrasonic atomization, atomization by centrifugation, electrolysis and spheroidization, or grinding and spheroidization. Preferably, the powder according to the present invention is obtained by gas jet atomization. The gas jet atomization process begins with the pouring of molten metal through a nozzle. The molten metal is then reached by jets of neutral gases, such as nitrogen or argon, possibly accompanied by other gases, and atomized into very small droplets which cool and solidify as they fall inside. of an atomization tower. The powders are then collected in a can. The gas jet atomization process has the advantage of producing a powder having a spherical shape, unlike the water jet atomization which produces a powder having an irregular shape. Another advantage of gas jet atomization is a good powder density, in particular thanks to the spherical shape and the particle size distribution. Yet another advantage of this method is good reproducibility of the particle size distribution.

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.

The powder according to the present invention can in particular be used in the following applications:

- selective laser sintering (Selective Laser Sintering or SLS);

- Direct metal laser sintering (Direct Metal Laser Sintering or DMLS);

- selective sintering by heating (Selective Heat Sintering or SHS);

- selective laser melting (Selective Laser Melting or SLM);

- electron beam melting (Electron Beam Melting or EBM in English);

- Laser Melting Deposition;

- direct deposit by energy contribution (Direct Energy Deposition or DED in English);

- direct metal deposition (Direct Metal Deposition or DMD in English);

- direct laser deposition (DLD);

- Laser deposition technology (LDT);

- engineering of clear shapes by laser (Laser Engineering Net Shaping or LENS in English);

- laser cladding technology (Laser Cladding Technology or LCT);

- laser freeform manufacturing technology (Laser Freeform Manufacturing Technology or LFMT);

- laser fusion deposition (Laser Metal Deposition or LMD in English);

- cold spraying (Cold Spray Consolidation or CSC);

- additive friction manufacturing (Additive Friction Stir or AFS); - Plasma spark sintering or flash sintering (Field Assisted Sintering Technology, FAST or spark plasma sintering in English); Where

- rotary friction welding (Inertia Rotary Friction Welding or IRFW.

The invention will be described in more detail in the example below. The invention is not limited to the embodiments described in the description above or in the examples below, and may vary widely within the scope of the invention as defined by the claims appended to the present description.

EXAMPLES Example 1: A first study was carried out on an alloy A having the composition indicated in Table 1 below, determined by ICP (Inductively Coupled Plasma) in% by mass. This alloy was obtained in the form of a powder for the SLM process using gas jet atomization (Ar). The particle size was essentially 3 µm to 100 µm, the D10 was about 35 µm, the D50 about 48 µm, and the D90 about 67 µm. [Table 1]

Using an EOS290 type SLM machine (EOS supplier), cracking specimens were produced in order to study the sensitivity of this alloy to cracking.

These specimens, which are represented in FIG. 2, have a particular geometry having a critical site favorable to the initiation of cracks. This critical site has a radius of curvature R. When printing these specimens, the main laser parameters used were: laser power of 370 W; 1400 mm / s scanning speed; 0.11 mm vector deviation; 60 µm layer thickness. The EOSM290 machine used allows the build plate to be heated by heating elements up to a temperature of 200 ° C. Crack specimens were printed using this machine with a plateau temperature of 50 ° C, 80 ° C, 100 ° C then 200 ° C. In all cases, the test pieces underwent a stress relief treatment after manufacture for 4 hours at 300 ° C.

After fabrication, the specimens were mechanically polished to 1 µm on the face shown in Figure 2 (Reference 1). The total length of the crack present at the critical initiation site of the specimens was measured using an optical microscope with a magnification of X50. The results are summarized in Table 2 below. [Table 2]

The results of this first study show that a reduction in the temperature of the plate between 200 ° C and 50 ° C is advantageous for reducing the sensitivity to cracking of alloy A. This result goes against several studies of the literature (see the prior art part above in the present description) which demonstrate a beneficial effect of preheating the construction plate above 150 ° C, or even above 350 ° C on cracking during the SLM process .

It should be noted that, in this example, the inventors deliberately placed themselves in conditions conducive to promoting cracking, in order to be able to effectively compare the impact of the temperature of the construction plate on the sensitivity to cracking. The use of test pieces with less complex shapes would not have made it possible to be sufficiently discriminating. The present example therefore serves only to show the impact of the build plate temperature on the susceptibility to cracking.

In the context of additional tests, not shown here, with compositions according to the present invention on another SLM machine which has a heating plate up to a temperature of 500 ° C, the inventors have demonstrated that a temperature of plateau from 250 to 350 ° C, and preferably from 280 to 330 ° C, also made it possible to avoid cracking on the cracking specimens, without degrading the mechanical performance at ambient temperature and at 200 ° C. Surprisingly, despite the increase in the temperature of the plate, there was no decrease in the mechanical properties in the raw state or after heat treatment. Without being bound by theory, it seems that, under these conditions, the alloys according to the present invention make it possible to maintain good aptitude for trapping addition elements in solid solution, and in particular Zr. An additional increase in the temperature of the plate, for example to 400 ° C or 500 ° C, seems to make it possible to reduce the rate of solidification during the SLM process and thus to limit the trapping of Zr in solid solution, which seems to lower the rates of solidification. mechanical properties in the raw state, as well as the suitability of the alloys for further hardening during post-manufacturing heat treatments, for example at 400 ° C. In conclusion, the temperature range of the plate which appears to maximize the susceptibility to cracking is between 150 ° C and 250 ° C.

Thus, the temperature ranges of the building plate recommended according to the present invention are either from 25 to 150 ° C, preferably from 50 to 130 ° C, more preferably from 80 to 110 ° C, even more preferably from 80 to 105 ° C. , or at a temperature of more than

250 to less than 350 ° C, preferably from 280 to 330 ° C.

Example 2:

A study was carried out with the aim of determining the influence of the temperature of the construction plate on the mechanical characteristics in traction at room temperature and at 200 ° C of parts obtained by additive manufacturing. For this, alloy A of Example 1 was used.

Using an EOSM290 type SLM machine (EOS supplier), cylindrical samples vertical with respect to the construction direction (Z direction) were produced in order to determine the mechanical characteristics of the alloy. These samples have a diameter of 11 mm and a height of 46 mm. When printing these samples, the main laser parameters used were: laser power of 370 W; 1400 mm / s scanning speed; 0.11 mm vector deviation; 60 µm layer thickness. Two build plate temperatures were tested: 100 ° C and 200 ° C.

In all cases, the samples underwent a stress relief treatment after manufacture for 4 hours at 300 ° C. The cylindrical samples were machined to obtain tensile specimens with the following characteristics, as described in Table 3 below and Figure 3:

[Table 3]

In Table 3 above and Figure 3, 0 represents the diameter of the central part of the test piece; M the width of the two ends of the test piece; LT the total length of the test piece; R the radius of curvature between the central part and the ends of the specimen; Le the length of the central part of the test piece and F the length of the two ends of the test piece.

After machining, some specimens underwent a heat treatment for 1 hour at 400 ° C. The heat treatment of 1 hour at 400 ° C makes it possible to simulate a post-manufacturing operation of hot isostatic compression or long-term aging at an operating temperature between 100 ° C and 300 ° C of the final part. The specimens were then tested in traction at ambient temperature (25 ° C) according to standard NF EN ISO 6892-1 (2009-10) and hot (200 ° C) according to standard NF EN ISO 6892-2 (2018). . The main results are summarized in Table 4 below.

[Table 4]

Of the two build plate temperatures tested (100 ° C and 200 ° C), the temperature of 100 ° C seems advantageous. Indeed, a construction plate temperature of 100 ° C made it possible to obtain better mechanical properties for all the conditions tested except for the tensile test carried out at 25 ° C on a raw state of expansion (without treatment. thermal post fabrication at 400 ° C).

The softer stress relief raw state at 25 ° C is however also advantageous because it implies lower levels of residual stresses when fabricating the part in SLM, and less distortion problems of the final part. .

For the two temperatures of the construction plate tested, the post-fabrication treatment of 1 h at 400 ° C allowed a significant increase in the elastic limit at 25 ° C compared to the raw expansion state (without post-fabrication heat treatment at 400 ° C). This type of post-manufacturing treatment is advantageous for maximizing the elastic limit for parts applications working at room temperature or at a temperature below 150 ° C. In contrast, for the two temperatures of the build plate tested, the post fabrication treatment of 1 h at 400 ° C caused a drop in the elastic limit at 200 ° C of about 26 MPa compared to the raw state. expansion (without post-manufacturing heat treatment at 400 ° C). A rough state of expansion seems advantageous for so-called “high temperature” applications, that is to say for parts working at around 200 ° C, or more generally at temperatures above 150 ° C.

Example 3:

Crack test specimens, identical to those of Example 1, were produced from alloy A described in Example 1 and from alloys F and H described in Table 5 below. Alloys F and H were also obtained in powder form for the SLM process using gas jet atomization (Argon). The particle size was essentially 3 µm to 100 µm, the D10 was 9 to 30 µm, the D50 from 25 to 44 µm, and the D90 from 51 to 64 µm.

[Table 5]

The laser parameters used were the same as those of Example 1: laser power of 370 W; 1400 mm / s scanning speed; 0.11 mm vector deviation; 60 µm layer thickness). The build plate was heated to 200 ° C for alloy A and to 100 ° C for alloys F and H. The test pieces underwent a stress relief treatment after fabrication for 4 hours at 300 ° C.

As in Example 1, the total crack length present at the critical crack initiation site was determined for each alloy.

Characterizations of the granular structure were also carried out on all the samples in EBSD (“Electron Back Scattered Diffraction”) using an EDAX camera and the OIM (“Orientation Imaging Microscopy”) software. . These characterizations were carried out using a ZEISS Ultra 55 type SEM-FEG with an energy of 15 keV on a field of 500 μm × 500 μm with a step of 0.5 μm.

Before characterization in EBSD, all samples were subjected to conventional mechanical polishing (sandpaper with water lubrication then polishing cloths with diamond suspension) down to 1 µm, followed by vibration polishing with an amplitude of 30% for 6 h, using a 50% dilution of SPM (colloidal silica gel) in water as a lubricant.

The total surface fraction of grains which each have an area greater than a given threshold value was calculated for all the samples. Several threshold values were used: 2.16 pm ² , 3.24 pm ² , 6.48 pm ² , 8.64 pm ² and 10.8 pm ² . The results are presented in Table 6 below. [Table 6]

The results of Table 6 above show that a total surface fraction of grains, each having a surface area greater than 2.16 μm ² , greater than 56%, preferably greater than 60%, and even more preferably greater than 64% is advantageous for completely suppressing cracking during the SLM process.

In other words, a total surface fraction of fine grains, each having a surface area less than 2.16 μm ² , less than 44%, preferably less than 40%, and even more preferably less than 36% is advantageous in order to avoid cracking during cracking. SLM process. These fine grains exhibited an equiaxial structure.

The results of Table 6 above show that a total surface fraction of grains, each having a surface area greater than 3.24 μm ² , greater than 48%, preferably greater than 52%, and even more preferably greater than 57% is advantageous for completely suppressing cracking during the SLM process.

The results of Table 6 above show that a total surface fraction of grains, each having a surface area greater than 6.48 μm ² , greater than 27%, preferably greater than 35%, and even more preferably greater than 40% is advantageous. to completely suppress cracking during the SLM process.

The results of Table 6 above show that a total surface fraction of grains, each having a surface area greater than 8.64 μm ² , greater than 22%, preferably greater than 27%, and even more preferably greater than 33%, is advantageous for completely suppressing cracking during the SLM process.

The results of Table 6 above show that a total surface fraction of grains, each having a surface area greater than 10.8 μm ² , greater than 19%, preferably greater than 25%, and even more preferably greater than 30% is advantageous for completely suppressing cracking during the SLM process.

The surface fraction of columnar grains measured is 22% for alloy A, 39% for alloy F and 60% for alloy H. This measurement was carried out with the OIM software in considering grains having a slenderness factor (ratio between length and width) greater than or equal to 3. This result has shown that a granular structure with a fraction of columnar grains greater than or equal to 22%, preferably greater than or equal to 25%, and even more preferably greater than or equal to 30%, is advantageous for the suppression of cracking during the SLM process.

The columnar grains in the absence of cracks generally have a length less than 500 μm, preferably less than 300 μm, more preferably less than 200 μm, even more preferably less than 150 μm. The columnar grains generally have a width of less than 150 μm, preferably less than 100 μm, preferably less than 50 μm, more preferably less than 30 μm, even more preferably less than 20 μm.

The granular structure to be sought in order to limit cracking therefore appears to be a structure with a surface fraction of columnar grains greater than 22% and a surface fraction of fine equiaxed grains each with a surface area <2.16 μm ² less than 44%.

This result goes against the current state of knowledge on the development of aluminum alloys for the SLM application, which strongly encourages the search for a fine and completely equiaxed structure for the removal of solidification cracks in aluminum alloys during SLM manufacturing. This equiaxial structure can in particular be obtained by the introduction of different types of seeds or nucleating agents, as illustrated for example in the following patent applications and publication: US2020024700A1; US2018161874A1; Martin et al: September 2017 vol 549 NATURE 365 “3D printing of high-strength aluminum alloys”.

In additional tests, the inventors have shown that the presence of Mg can induce micro-cracking on samples with a predominantly columnar structure. Micro-cracks propagate at grain boundaries parallel to columnar grains. The presence of Mg can also lead to the generation of smoke during the SLM process, with a risk of instability of the Laser process. Thus, in a variant of the present invention, the Mg content is preferably less than 2%, preferably less than 1%, and more preferably less than 0.05%.

Claims

1. Method of manufacturing a part comprising the formation of successive solid metal layers (20i ... 20 _n ), 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), said filler metal, the filler metal being subjected to an energy input so as to melt and to form, by solidifying, said layer, wherein the filler metal takes the form of a powder (25), exposure of which to an energetic beam (32) results in melting followed by solidification to form a solid layer (20i ... _N ), the method being characterized in that the part is manufactured at a temperature of 25 to 150 ° C; the method also being characterized in that the part has a grain structure such that the surface fraction of the equiaxed grains each having a surface area of less than 2.16 μm ² is less than 44%, preferably less than 40%, preferably less than 36%; and a grain structure such that the surface fraction of columnar grains is greater than or equal to 22%, preferably greater than or equal to 25%, preferably greater than or equal to 30%; the method also being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements:

- Sc, according to a mass fraction of less than 0.30%, preferably less than 0.20%, preferably less than 0.10%, more preferably less than 0.05%; - 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%;

- the rest being aluminum.

2. A method of manufacturing a part comprising the formation of successive solid metal layers (20i ... 20 _n ), 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), said filler metal, the filler metal being subjected to an energy input so as to melt and to form, by solidifying, said layer, wherein the filler metal takes the form of a powder (25), exposure of which to an energetic beam (32) results in melting followed by solidification to form a solid layer (20i ... _N ), the method being characterized in that the part is manufactured at a temperature of 25 to 150 ° C; the method also being characterized in that the part has a grain structure such that the surface fraction of the equiaxed grains each having a surface area of less than 2.16 μm ² is less than 44%, preferably less than 40%, preferably less than 36%; and a grain structure such that the area fraction of columnar grains is greater or equal to 22%, preferably greater than or equal to 25%, preferably greater than or equal to 30%; the method also being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements:

- Optionally Fe, according to a mass fraction of 0.50 to 7.00%, preferably from 1.00 to 6.00% according to a first variant; or according to a mass fraction less than or equal to 1.00%, preferably less than or equal to 0.5%, preferably less than or equal to 0.3%, more preferably less than or equal to 0.1%, even more preferably less Where equal to 700 ppm according to a second variant;

- the rest being aluminum.

3. Method according to any one of the preceding claims, in which the part is manufactured at a temperature preferably from 50 to 130 ° C, more preferably from 50 to 110 ° C, even more preferably from 80 to 110 ° C, even more. preferably from 80 to

105 ° C.

4. A method of manufacturing a part comprising the formation of successive solid metal layers (20i ... 20 _n ), 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), said filler metal, the filler metal being subjected to an energy input so as to melt and to form, by solidifying, said layer, wherein the filler metal takes the form of a powder (25), exposure of which to an energetic beam (32) results in melting followed by solidification to form a solid layer (20i ... 20 _n ), the method being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements:

- 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 at least one element chosen from: Ni, Mn, Cr and / or Cu, according to a mass fraction of 0.50 to 7.00%, preferably from 1.00 to 6.00% each; preferably, according to a mass fraction of less than 25.00%, preferably less than 20.00%, more preferably less than 15.00% in total;

5. Method of manufacturing a part comprising a formation of successive solid metal layers (20i ... 20 _n ), 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), said filler metal, the filler metal being subjected to an energy input so as to melt and to form, by solidifying, said layer, wherein the filler metal takes the form of a powder (25), exposure of which to an energetic beam (32) results in melting followed by solidification to form a solid layer (20i ... 20 _n ), the method being characterized in that the filler metal (25) is an aluminum alloy comprising at least the following alloying elements:

- optionally at least one element chosen from: Ag according to a mass fraction of 0.06 at 1.00% and / or Li in a mass fraction of 0.06 to 1.00%;

6. A method according to any preceding claim, wherein the aluminum alloy comprises:

7. Method according to any one of the preceding claims, comprising, following the formation of the layers (20i ... 20 _n ),

- hot isostatic compression.

8. Method according to any one of the preceding claims, in which the addition of La, Bi, Mg, Er, Yb, Y, Sc and / or Zn is avoided, the preferred mass fraction of each of these elements then being lower. at 0.05%, and preferably less than 0.01%.

9. Method according to any one of the preceding claims, in which the aluminum alloy also comprises at least one element for refining the grains, for example AITiC or AITÎB2, in an amount less than or equal to 50 kg / ton, of preferably less than or equal to 20 kg / tonne, even more preferably 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.

10. Metal part obtained by a method according to any one of claims 1 to 3 and 6 to 9, characterized in that it has a grain structure such that the surface fraction of equiaxed grains each having a surface area of less than 2, 16 µm ² is less than 44%, preferably less than 40%, preferably less than 36%; and such that the surface fraction of columnar grains is greater than or equal to 22%, preferably greater than or equal to 25%, more preferably greater than or equal to 30%.

11. Powder comprising an aluminum alloy which comprises at least the following alloying elements:

- Zr, according to a mass fraction of 0.30-1.40%, preferably 0.40-1.40%, more preferably 0.50-1.40%, even more preferably 0.60-1.40%, even more preferably 0.70-1.40%, even more preferably 0.80-1.20%;

- Zn, in 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 0.1%, even more preferably less than 0.05%;

- optionally at least one element chosen from: Ni, Mn, Cr and / or Cu, according to a mass fraction of 0.50 to 7.00%, preferably from 1.00 to 6.00% each; preferably, according to a mass fraction less than 25.00%, preferably less than 20.00%, more preferably less than 15.00% in total; optionally at least one element chosen from: Hf, Ti, Er, W, Nb, Ta, Y, Yb, Nd, Ce, Co, Mo, Lu, Tm, V and / or mischmetal, according to a mass fraction less than or equal at 5.00%, preferably less than or equal to 3% each, and less than or equal to 15.00%, preferably less than or equal to 12%, more preferably less than or equal to 5% in total;

- the rest being aluminum.

12. Powder comprising an aluminum alloy which comprises at least the following alloying elements:

Zr and at least one element chosen from: Ti, V, Sc, Hf, Er, Tm, Yb and Lu, in a mass fraction of 0.30-1.40%, preferably 0.40-1.40%, more preferably 0.50-1.40%, even more preferably 0.600-1.4%, even more preferably 0.70-1.40%, even more preferably 0.80-1.20% in total , knowing that Zr represents from 10 to less than 100% of the ranges of percentages given above;

- the rest being aluminum.