Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/20—Direct sintering or melting
  • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/06—Metallic powder characterised by the shape of the particles
  • B22F1/065—Spherical particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/09—Mixtures of metallic powders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/14—Treatment of metallic powder
  • B22F1/142—Thermal or thermo-mechanical treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
  • B33Y40/20—Post-treatment, e.g. curing, coating or polishing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
  • B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y80/00—Products made by additive manufacturing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2301/00—Metallic composition of the powder or its coating
  • B22F2301/05—Light metals
  • B22F2301/052—Aluminium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2301/00—Metallic composition of the powder or its coating
  • B22F2301/10—Copper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2301/00—Metallic composition of the powder or its coating
  • B22F2301/15—Nickel or cobalt
  • B22F2301/155—Rare Earth - Co or -Ni intermetallic alloys
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2301/00—Metallic composition of the powder or its coating
  • B22F2301/20—Refractory metals
  • B22F2301/205—Titanium, zirconium or hafnium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2303/00—Functional details of metal or compound in the powder or product
  • B22F2303/20—Coating by means of particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2304/00—Physical aspects of the powder
  • B22F2304/10—Micron size particles, i.e. above 1 micrometer up to 500 micrometer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• the technical field of the invention is a process for manufacturing an aluminum alloy part, using an additive manufacturing technique.
• 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.
• 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.
• 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.
• selective laser sintering techniques selective laser sintering, SLS or direct metal laser sintering, DMLS
• SLM selective laser melting
• EBM electron beam melting
• LMD deposition by laser fusion
• 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.
• 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.
• 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 TM developed by NanoAl 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.
• 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:
• 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 ⁇ m 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
• 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%;
• Ni, Mn, Cr and / or Cu 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;
• Hf 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;
• 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 ...
• M digital model
• 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 ⁇ m 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
• - 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%;
• Ni, Mn, Cr and / or Cu 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: 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 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;
• 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.
• 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.
• 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.
• 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.
• 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.
• 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%;
• - 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%;
• Si optionally Si, according to a mass fraction less than or equal to 1.00%, preferably less than or equal to 0.50%;
• 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.
• the composition of the mischmetal is generally about 45 to 50% cerium, 25% lanthanum, 15 to 20% neodymium and 5% praseodymium.
• 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%.
• the addition of Fe and / or Si is avoided.
• 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.
• 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.
• AITiC or AITÎB2 for example in the form AT5B or AT3B
• 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.
• 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%;
• - 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%;
• Ni, Mn, Cr and / or Cu 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;
• Hf 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;
• 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.
• 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.
• 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;
• - 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%;
• Ni, Mn, Cr and / or Cu 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: 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 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 or equal to 700 ppm according to a second variant;
• 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.
• 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.
• 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.
• 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.
• 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).
• the method can use a laser, and optionally several lasers.
• 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
• CIC - hot isostatic compression
• 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.
• 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.
• Hot isostatic compression can in this case advantageously replace dissolution.
• 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.
• 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.
• 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.
• assembly method it is possible to achieve a mechanical deformation of the part, for example after additive manufacturing and / or before the heat treatment.
• 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 ⁇ m 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%;
• - 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%;
• Ni, Mn, Cr and / or Cu 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;
• Hf 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;
• 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;
• - 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 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%;
• Ni, Mn, Cr and / or Cu 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: 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 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;
• 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.
• 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:
• - 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%;
• - 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%;
• Si optionally Si, according to a mass fraction less than or equal to 1.00%, preferably less than or equal to 0.50%;
• 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.
• AITiC or AITÎB2 for example in the form AT5B or AT3B
• 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%.
• the addition of Fe and / or Si is avoided.
• 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.
• Figure 1 is a diagram illustrating an additive manufacturing process of SLM type, or EBM.
• 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.
• Figure 3 is a test specimen geometry used to perform tensile testing, as used in the examples.
• FIG. 1 generally describes an embodiment, in which the additive manufacturing method according to the invention is implemented.
• 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 .
• 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 ⁇ m.
• SLM selective laser melting
• EBM electron beam melting
• 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.
• 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.
• the powder is projected and melted simultaneously by a generally laser beam. This process is known as laser melting deposition.
• DED direct energy deposition
• DMD direct metal deposition
• DLD Direct Laser Deposition
• laser deposition technology Laser Deposition Technology, LDT
• laser metal deposition Laser Metal Deposition
• laser clean shape engineering Laser Engineering Net Shaping, LENS
• laser plating technology Laser Cladding Technology, LCT
• LFMT laser freeform manufacturing technology
• 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.
• 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.
• 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.
• 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.
• 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 sphericity of a powder can for example be determined using a morphogranulometer
• 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);
• satellites 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.
• infusible, insoluble particles for example oxides or particles of titanium diboride T1B2 or particles of titanium carbide TiC
• powder and / or when mixing the primary powders 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.
• 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.
• 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:
• SLS Selective Laser Sintering
• Direct metal laser sintering Direct Metal Laser Sintering or DMLS
• SHS Selective Heat Sintering
• SLM Selective Laser Melting
• DLD direct laser deposition
• LDT Laser deposition technology
• LCT Laser Cladding Technology
• LFMT Laser Freeform Manufacturing Technology
• CSC Cold Spray Consolidation
• 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 ⁇ m to 100 ⁇ m, the D10 was about 35 ⁇ m, the D50 about 48 ⁇ m, and the D90 about 67 ⁇ m. [Table 1]
• 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.
• the main laser parameters used were: laser power of 370 W; 1400 mm / s scanning speed; 0.11 mm vector deviation; 60 ⁇ m 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.
• 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.
• 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.
• 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.
• 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
• 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.
• the main laser parameters used were: laser power of 370 W; 1400 mm / s scanning speed; 0.11 mm vector deviation; 60 ⁇ m layer thickness.
• Two build plate temperatures were tested: 100 ° C and 200 ° C.
• 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.
• 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. .
• 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.
• 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.
• 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 ⁇ m 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.
• 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 ⁇ m ⁇ 500 ⁇ m with a step of 0.5 ⁇ m.
• a total surface fraction of fine grains each having a surface area less than 2.16 ⁇ m 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 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 ⁇ m, preferably less than 300 ⁇ m, more preferably less than 200 ⁇ m, even more preferably less than 150 ⁇ m.
• the columnar grains generally have a width of less than 150 ⁇ m, preferably less than 100 ⁇ m, preferably less than 50 ⁇ m, more preferably less than 30 ⁇ m, even more preferably less than 20 ⁇ m.
• 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 ⁇ m 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”.
• 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.
• the Mg content is preferably less than 2%, preferably less than 1%, and more preferably less than 0.05%.

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