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EP-4735194-A1 - METAL-COATED ALUMINIUM ALLOY PARTICLES, PROCESS FOR PRODUCING SAME, AND ADDITIVE PROCESS USING THE COATED, ALUMINIUM ALLOY-PARTICLES

EP4735194A1EP 4735194 A1EP4735194 A1EP 4735194A1EP-4735194-A1

Abstract

The present invention concerns a metal-coated aluminium alloy particles (1) (= Me-coated Al-alloy particles), comprising, • individual particles (= Al-particles) of the aluminium alloy (= Al-alloy) in the form of powder (2p) or of a wire (2w), with • a continuous coating (3c) of a metal composition (3) (= Me-coating) applied over substantially a whole area of the Al-particles, wherein the metal composition comprises a metal mixture (Me + MeOx) of a metal (Me) selected from titanium or zirconium (i.e., Me = Ti or Zr) and of an oxide of formula, MeOx, of the same metal (i.e., Me + MeOx = Ti + TiOx or Zr + ZrOx), wherein x = 0.01 to 0.5, and oxygen atoms are present in the metal mixture between 0.1 and 50 atom%, preferably between 1 and 33 atom% on an atomic base (= atom.%) of the metal mixture, preferably between 10 and 20 atom.%.

Inventors

  • KAIRET, THOMAS
  • RIGO, OLIVIER
  • HEMBERG, Axel
  • GODFROID, Thomas

Assignees

  • Sirris
  • Materia Nova

Dates

Publication Date
20260506
Application Date
20240516

Claims (15)

  1. 1 . Metal-coated aluminium alloy particles (1) (= Me-coated Al-alloy particles), comprising, • individual particles (= Al-particles) of the aluminium alloy (= Al-alloy) in the form of powder (2p) or of a wire (2w), with • a continuous coating (3c) of a metal composition (3) (= Me-coating) applied over substantially a whole area of the Al-particles, wherein the metal composition comprises a metal mixture (Me + MeOx) of a metal (Me) selected from titanium or zirconium (i.e., Me = Ti or Zr) and of an oxide of formula, MeOx, of the same metal (i.e., Me + MeOx = Ti + TiOx or Zr + ZrOx), wherein x = 0.01 to 0.5, and oxygen atoms are present in the metal mixture between 0.1 and 50 atom%, preferably between 1 and 33 atom% on an atomic base (= atom.%) of the metal mixture, preferably between 10 and 20 atom.% wherein the Me-coating (3c) is present in the Al-alloy powder in an amount comprised between 0.5 and 6 wt.% of the total weight of the Me-coated Al-alloy particles (1).
  2. 2. Me-coated Al-alloy particles according to claim 1 , wherein the Me-coating (3c) is present in the Al-alloy powder in an amount comprised between 0.8 and 4 wt.%, preferably between 1 and 3 wt.% of the total weight of the Me-coated Al-alloy particles (1), and is preferably applied by physical vapour deposition (PVD), preferably by magnetron sputtering.
  3. 3. Me-coated Al-alloy particles according to claim 2, wherein the individual particles (2p) are in the form of a powder formed of substantially spherical individual particles having a mean diameter (Dp) comprised between 20 and 200 pm, preferably between 30 and 120 pm, measured according to ISO13320:2020.
  4. 4. Me-coated Al-alloy particles according to claim 3, wherein the Me-coating (3c) has an average thickness (tp) comprised between 50 and 300 nm, preferably between 100 and 200 nm.
  5. 5. Me-coated Al-alloy particles according to claim 2, wherein the individual particles (2w) are in the form of a wire having a mean diameter (Dw) comprised between 500 pm and 10 mm, preferably between 1 and 5 mm.
  6. 6. Me-coated Al-alloy particles according to claim 5, wherein the Me-coating (3c) has an average thickness (tw) comprised between 12 and 18 pm, preferably between 13 and 15 pm.
  7. 7. Me-coated Al-alloy particles according to any one of the preceding claims, wherein the aluminium alloy is an aluminium alloy of the series 2000, 6000 or 7000, preferably an aluminium alloy of the type 7075, 2024, or 6061 .
  8. 8. Me-coated Al-alloy particles according to any one of the preceding claims, wherein the metal (Me) of the metal composition (3) has at least 2N (= 99%) purity, preferably at least 3N (= 99.9%) purity.
  9. 9. Process for producing Me-coated alloy particles (1) according to any one of the preceding claims, comprising the following steps, • providing the Al-particles (2p, 2w) formed of individual particles having an outer area, • depositing the metal composition (3) comprising the metal mixture (= Me + MeOx) onto the individual particles (2p, 2w) until forming the continuous coating (3c) over substantially the entire outer area of the individual particles, to form the Me-coated Al-particles (1), • storing the Me-coated Al- particles ready for use.
  10. 10. Process according to claim 9, wherein deposition of the metal composition is carried out by a dry deposition method, preferably by physical vacuum deposition (PVD), more preferably by magnetron sputtering or, alternatively, or by chemical vapour deposition (CVD), preferably by plasma enhanced chemical vapour deposition (PECVD).
  11. 11. Process according to claim 10, wherein a gas composition (5g) for forming a plasma (5p) for the dry deposition of the metal composition (3) is controlled such as to ensure that an amount of oxygen atoms present in the metal mixture is comprised between 0.1 and 50 atom%, preferably between 1 and 33 atom.% on an atomic base (= atom.%) of the metal mixture, preferably between 10 and 20 atom.%.
  12. 12. Process for producing a solid part (11s) made of Al-alloy by additive manufacturing comprising the following steps, • providing a Me-coated Al-alloy particles (1) according to any one of claims 1 to 8, • feeding the Me-coated Al-alloy particles, • locally melting the Me-coated Al-alloy particles (1) with an energy source according to a predefined geometry to form a melted pool (1 m) which forms a solid part layer (11sL) upon cooling, wherein the energy source is selected among a laser (13L) and an electric arc (13a), • repeating a number of times the former two operations on top of the solid part layer (11sL) thus formed to form successive solid part layers (11sL) of desired geometries , until forming the solid part (1 1s).
  13. 13. Process according to the preceding claim, wherein the additive manufacturing is selected among the group of laser powder bed fusion (L-PBF), arc additive manufacturing (WAAM), or direct energy deposition (DED).
  14. 14. Process according to claim 12 or 13, wherein the solid part (11s) is exposed to a heat treatment, for increasing mechanical properties of the solid part.
  15. 15. Process according to anyone of claims 12 to 14, either, • for the production of an Al-alloy part, or • for repairing an existing damaged part.

Description

METAL-COATED ALUMINIUM ALLOY PARTICLES, PROCESS FOR PRODUCING SAME, AND ADDITIVE PROCESS USING THE COATED, ALUMINIUM ALLOY-PARTICLES FIELD OF THE INVENTION [0001] The invention relates to aluminium alloy particles suitable for additive processing with substantially reduced hot cracking. In particular, it concerns aluminium particles in the form of powder or wire coated with a continuous coating of a metal composition comprising a metal mixture (Me + MeOx) of a metal (Me) selected from titanium or zirconium (i.e., Me = Ti or Zr) and of an oxide of formula, MeOx, of the same metal (i.e., Me + MeOx = Ti + TiOx or Zr + ZrOx), [0002] The use of the metal coated particles of the present invention in additive manufacturing of parts substantially reduces the occurrence of hot cracking and reduces formation of pores caused by solid state trapping of hydrogen. BACKGROUND OF THE INVENTION [0003] A wide variety of aluminium allpys (= Al-alloy) are available showing a range of different mechanical properties. As shown in Figure 1 , Al-alloys parts are traditionally produced either by casting methods, or by machining wrought Al-alloys. Specific Al-alloy grades are more suitable for casting methods, such as the series Nxx.x, with N = 1 to 5 or 7, and other are more suitable wrought Al-alloys, such as the series Nxxx each x independently varying from 0 to 9. High performance Al-alloy parts are generally produced with wrought Al-alloys. [0004] Additive manufacturing or additive processing is yet an alternative and attractive production technique illustrated in Figures 5(a)&5(b), 6(a)&6(b), and 7 (discussed in more details in continuation), allowing complex geometry 3D-parts to be produced by feeding and laying Al-alloy particles onto a support to form a layer and continuously locally melting and then allowing to solidify the Al-alloy according to a predefined geometry as it is being laid. The operation is repeated on top of a thus formed solidified Al-alloy layer until forming the 3D-part. The processing conditions in additive manufacturing are close to autogenous welding which, as well known by the skilled person, can be problematic and even impossible for some Al-alloy grades. Additive processing can also be used for repairing a damaged part made of an Al-alloy. Since the Al-alloy particles must be melted, it is clear that only weldable Al-alloy grades are suitable for additive processing. As indicated in Figure 1 , heat treatable alloys are more often used for high strength applications than non-heat treatable alloys, because the heat treatment causes precipitation hardening of the alloy. Casting Al-alloys generally have lower mechanical properties than wrought Al-alloys, the latter heat treatable alloys are preferred for producing advanced engineering parts suitable for aerospace applications and the like. Wrought Al-alloys can also increase their mechanical properties by strain hardening processes, every time such wrought Al-alloys is laminated, forged or otherwise strained during the manufacturing of a part. [0005] As in welding applications, the biggest challenge with additive processing is hot cracking. Hot cracking happens after the melted Al-alloys is cooled. Depending on the composition and associated phase diagram of the components forming the Al-alloy, upon colling, some alloying components of the Al-alloy migrate into the liquid phase remaining between the growing dendrites and are eventually concentrated at the grain boundaries. The stress of solidification may cause cracking at the grain boundaries. Because this problem has not been satisfactorily solved to date, additive processing with heat treatable wrought Al-alloys is still incipient. Cracking sensitivity curves are available for each possible element added to aluminium. Figure 2 shows examples of such cracking sensitivity curves for Si (e.g., 4xxx grades), Cu (e.g., 2xxx grades), Mg (e.g., 5 xxx grades), and Mg-SI (e.g., 6xxx grades). These curves show the probability of cracking as a function of the amount of the added element. The higher the curve, the higher the probability of having hot cracking. For example, the peaks of the curves for silicon, magnesium, and magnesium silicide cracking curves are at around 1 %, whilst the peak for Cu is at about 3%. [0006] EP3351322 proposes an additive process of Al-alloys avoiding another problem associated with Al-alloys processed with an additive technique, namely oxidation of the aluminium during melting. The problem is solved by coating the Al-alloy powder with a metallic material, which causes an exothermic reaction with aluminium when melted together. This causes turbulences which prevent the formation of an oxide layer and disperse instead the aluminium oxides thus formed within the bulk of the solidified part. This document does not address the problem of hot cracking. [0007] WO2020212312 describes a method for functionalizing Al-alloy powder particles with nanoparticles of a second material selected